Paul Davies, a highly respected theoretical physicist recently stated that "the essence of life is information." ¹ I will describe how the essence of information is plasticity, that information is encoded energy requiring what neurophysiologists call plasticity. Plasticity is the ability of neurons through their synapses to have memory, learn, adapt and evolve in response to their environment. I will show that Ovonic memories, both optical and electrical, have rich and deep new physics that make them cognitive devices and therefore open up a huge new field of chalcogenide-based intelligent computers, intelligence that works in a similar manner to the brain. We have shown that the plasticity necessary for an intelligent opto-electronic computer is a function of energy pulses, whether electrical or optical.

Philips Research has been working on improvements of optical disc storage technology for three decades. In this period, optical discs have become the technology of choice for storing and sharing of data on removable media. In 30 years we have made an improvement of about 2 orders of magnitude in both data rate and storage density. The new Blu-ray Disc (BD) optical storage system offers 25 GB on a single layer, with 36 Mbps base data rate. Philips has made an optical pick-up unit with a single lens and a single detector that can be used for BD as well as for DVD and CD. We doubled the BD-storage capacity and increased the data rate by another order of magnitude in our two-dimensional optical storage format TwoDOS. Furthermore, we are exploring near-field optical storage for capacities beyond Blu-ray Disc. By using a solid immersion lens in a conventional actuator, we have realized an experimental laboratory system with remarkable robustness. We have found that near-field optical storage may be used on discs that have a cover layer to protect the data from scratches.

Optical technique for data storage was driven from the challenges to achieve data storage performance required by the user. The first attempt to address the recording density improvement over HDD using magneto-optic technology started over thirty years ago. Subsequent efforts to develop 15", 12" and 5 and 1/4" WORM disc drives met with limited success. Advances in semiconductor lasers, lithography, and auto focusing and tracking techniques finally allow the development of the Compact Disc to answer the call for improvement in audio recording technology and data distribution in mid to late 1980. Recordable and erasable technology then followed with the introduction of CD-R, CD-RW and MO drives and media. By early 1990, advances in high density recording with the use of shorter wavelength lasers, larger n.a. lenses, improved lithographic and data compression techniques, allows the development of 4.7 GB DVD drives and discs to answer the challenge for recording 2-hour high quality movies on a CD size disc. Recordable and erasable DVD became available in 2000, and Dual Layer DVD was introduced last year . With the advent of HDTV and movie in recent years, Storage of 25 GB data in a DVD disc is needed. Blue-ray and HD-DVD are the leading technologies to answer this challenge. Looking to the future, optical storage areal density of one to two orders of magnitude improvement will be required to compete with HDD which is now reaching 133 Gb/in² . In addition, high data transfer rate of 1Gb/s, data security, copy protection, ease of use, cost and standards issues sums up the monumental challenges facing the optical recording industry in the years to come. Some of the leading technologies, such as multi-layer, new encoding schemes, volume recording, near-field optics, micro-optics, domain expansion, UV laser, holographic storage, could provide the answers. Meeting these challenges, optical storage could become the dominant recording technology to satisfy the data storage needs for the convergent world of consumer electronics, information, and communication.

To break through the diffraction limit by optical super-resolution thin films is very attractive for the applications in optical and photonic devices. Large optical nonlinearities, such as optic-thermal nonlinearity and the third order optical nonlinearity, of optical thin film materials are very critical to super resolution optical storage, imaging, lithography, and the enhancement of the throughput of the optical near-field nano-aperture. The super-resolution effect in optical thin films or film structures under laser irradiation is focused in this paper. And its applications, especially in super high density optical storage are analyzed and discussed.

There are two basic requirements in the field of optical storage data devices. The first is the demand for the improvement of memory capacity to manage the increased data capacity in personal and official purposes. The second is the demand for small sized optical storage devices for mobile multimedia digital electronics, including digital camera, PDA and mobile phones. To summarize, for the sake of mobile applications, it is necessary to develop optical data storage devices which have simultaneously a large capacity and a small size. Small form factor optical disk drive (SFF ODD) is expected to become a good match for mobile applications due its advantages over other devices in cost and removability. Nowadays, many companies and research institutes including universities cooperate together in the research on SFF ODD and other related optical storage devices. Due such active researches, it is expected that SFF ODD will be widely used in mobile applications in the very near future.

On the excess Sb effect for the dynamics of rapid crystallization in eutectic amorphous films, the crystallization is described by the propagation of crystalline region with high velocity in the interface separating the crystalline and amorphous phase for InSb and AgInSbTe materials. From this analysis, it is clear that the crystallization is grown up in the boundary of crystalline-amorphous region of eutectic materials, which is different from the pseudo-binary compound GeSbTe media. Similarly, the current-induced crystallization can be investigated by the electron- phonon interaction. If a certain fraction of the valence band electrons are excited into the conduction band, the reaction of TA phonon take the stability of the crystal.

Multi-wavelength and multi-level optical storage based on novel photochromic materials is a promising approach to increase recording density and transfer rates signicantly. In our research, three laser beams with dierent wavelength are simultaneously used to record information in one recording layer, which consists three kind of photochromic materials with spectrum sensitivity suitable for each used laser beam. On the other hand, the reectivity of photochromic materials varies nonlinearly with the exposure energy, which shows feasible for multilevel optical recording. The principle of the experimental system construction and a results are described in this paper. The proposed multi-wavelength and multi-level photochromic recording has the great potential to be applicable for future high density optical data storage.

We shall give an overview of the several off-line testing methods which are recently developed. The specifics some of the methods will be described in details. Relations between the tested parameters and manufacturing process will analysed. Several indications will be described for substrates optimization, evaluation of the dyes for recordable media, control and correction of the dye distribution on the blank substrates. Relation of the dye coating with the process conditions will be described. Important process steps and their evidence in the various tested parameters on the ready media will be analysed. Further consequences of the manufacturing technology onto the performance of the final media will be discussed.

Light rare earth-heavy rare earth-transition metal (LRE-HRE-TM) thin films are a kind of important recording media. A lot of researches have been carried out on the LRE-HRE-TM thin films to improve its properties for data storage application and fruitful results have been achieved. This report gives a glance on the evolution of the research on LRE-HRE-TM recording media. At the same time, combined with the hybrid recording technology, some experimental results obtained on LRE-HRE-TM recording media are discussed, which suggest the promising prospect of the LRE-HRE-TM media in hybrid recording application.

Before reaching the true heat assisted magnetic recording, which is in optical near-field case for high recording density, the component level researches are needed. This requires a platform to support these kinds of researches. In this talk, the platform structure is introduced and its functions of researching on media material and structures, interface, overcoat and lubricant are discussed. Finally, some experimental results are presented.

TbFeCo is an important MO media material and even a candidate for hybrid recording. Our experimental results show that two magnetic phases can co-exist in TbFeCo films with orthogonal easy axes, which are along the film plane or out-of-plane. Suggested by the hystersis curves measured by the extraordinary Hall effect (EHE) and vibrated sample magnetometer (VSM), there is a transition region between domains with different easy axes of magnetization. The exchange coupling in between acts as a biased field, which may migrate the magnetic switching field for each loop.

We present an analytic expression for the point-function demagnetization tensor of equilateral triangular prism recording media made by nanosphere lithography. This result can be used to calculate the demagnetization field in the prism and may improve the precision in finite element micromagnetic models, especially for complex boundary geometric shapes. The corresponding demagnetization factors are calculated through the expression. The distribution of the demagnetization field is discussed at various aspect ratios with magnetization perpendicular to the triangle plane. It is found that the demagnetization field is enhanced in the vicinity of the surfaces and strongly depends on the aspect ratio.

The use of magnetic capping effect can enhance the head sensitivity of the heat assisted magnetic recording (HAMR). The principle of this effect was analyzed theoretically. The GdFeCo film was used as the capping layer and TbFeCo film was used as the recording layer. Through theoretical calculation we found that a large capping field in the same direction with the external field can be generated at the interface because of the exchange coupling effect, which had increased the effective strength of the external field. Thus, the head sensitivity was improved greatly and the data transfer rate could be faster. We expected that this idea can be used to help write the medium with much larger cocervity such as L1₀FePt.

The (Sm,Nd)(Tb,Dy)Co thin Film had been prepared with spf-430H r.f.-magnetron sputtering system. The effects of heavy rare earth Tb, Dy substituted by light rare earth Sm, Nd on the magnetic and magneto-optical properties have been investigated. With the increasing of light rare earth Sm, Nd composition, the saturation magnetization Ms, the reflectivity R and the Kerr rotation angle θ_k are increased, while the coercivity (Hc) is decreased distinctly. This can be explained with the ferri-magnetic structure of RE-TM alloy. Mr/Hc Ratio is increased with the increasing of Sm composition in SmTbCo and SmDyCo. The influence of composition and sputtering conditions on perpendicular anisotropy films are reported in detail.

CoPtCu nanocomposite films were prepared by magnetron sputtering. The dependences of texture and magnetic properties on film thickness, Cu atomic fraction and annealing conditions are investigated. After annealing at 640°C, (001) orientation was achieved in the Co₄₁Pt₄₉Cu₁₀ film, with a coercivity of 8.4 kOe and magnetization of 650 emu/cm³. A short-range domain structure is observed indicating weak inter-grains exchange coupling after annealing. The results suggest that this system might be applicable to ultra high-density perpendicular hybrid recording media.

The minimax optimization method is applied broadly to industrial design, agricultural test, automation, economy and so on. In the field of magnetic recording, we utilize it in determining optimal fabricating conditions of recording thin film media. In the procedure of thin film fabrication, the coercivity, the remenance- hickness product and the squareness ratio of magnetic thin film are considered as multiple-objective functions of these parameters: element composition, atmosphere pressure, substrate temperature, post-annealing temperature and thin film thickness. The optimal fabricating conditions and high performance of CoCrPt thin film are obtained using the minimax optimization based on a series of experiments and data. The coercivity of CoCrPt thin film is up to 3523Oe; the remenance-thickness product is up to 1.75 memu/cm²; and the squareness ratio is up to 0.83. The results show that the minimax optimization method can improve the fabricating conditions of recording thin film and is helpful for a short path of achieved high performance of CoCrPt thin film.

Hybrid recording is one of the most promising candidates to breaking down the technical barrels of the extremely high density recording. To acquire the goal, the recording grains must get much smaller than ever before, and at the same time, the track pitch must also decrease from ~200nm to ~70nm. Thus the design margin for the tracking servo shrinks dramatically. This paper tries to answer questions like these: is the existing scheme still work on the conditions of the hybrid recording? If not, what are the key elements of the novel one? How to design such a fine servo system? The main concern of designing a servo system is relevant to several key factors, such as recording density; mechanics; signal to noise ratio. Some parameters should be assumed. This paper anticipates the requirements of the hybrid recording, and some assumptions (including recording density, mechanical characteristics, SNR, etc) have been made. Then, the requirements that the servo system should be met can be calculated. Results show that a novel tracking servo system should be designed. Finally a novel servo scheme is presented.

FePt/C and FePt/Ag multilayer films have been prepared by pulsed filtered vacuum arc deposition system and subsequent rapid thermal annealing were performed on SiO₂/Si (001) substrates. A strong dependence of coercivity and ordering on C concentration was found in FePt/C films. FePt/C nanoparticles started ordering at 350°C, the longitudinal coercivity got to 8.1 kOe and the saturation magnetization got to 802 emu/cm³ by decreasing C concentration to 21% at 450°. But the coercitity didn't have the same tendency with Ag-doped FePt films. The films with Ag concentration of 22% started ordering at 400°C and the longitudinal coercivity got to 10.6 kOe and the saturation magnetization was 624 emu/cm³ at 500°C. The obtained results suggest that the films might be applicable to optical-magnetic hybrid recording media.

This paper suggests a mode of the heat transfer between hybrid recording medium and the sliding air film. According to the differential theory and the symmetrical theory, the energy of the laser heating can be removed in subsection; the laser power from waveguide in track can be looked as the power in a moment. So we can get the simulation results of the average temperature of the medium. Since hybrid recording head gap is less than 20nm, the temperature gradient field of air film can be simulated by boundary layers theory. This paper simulated air film temperature heated by the near field optical in hybrid recording. The results show that air film heating-up has influence on the slider bearing system, such as fly height and pose. The simulation of the slider fly height and pose illuminate that in the extreme the effect of heating-up of the air film on fly height and pose must be emphasized enough.

We designed and built up an apparatus for measuring the properties of magnetic coupling thin films and hybrid recording media. The temperature of the tested points of the thin film samples change as irradiated by focused laser beam through adjusting laser power. By calculation, we also simulated the distribution of temperature in TbFeCo magneto-optical films irradiated by laser, in order to get the relationship between the film coercive force and the irradiating laser power. Using this apparatus, we can determine the Curie temperature and compensation temperature of the films. The apparatus might present an effective approach for studying the variation of magneto-optical characteristics of films at different temperatures and the properties of magnetic coupling multilayer films, and it could be useful for studying hybrid recording.

In this paper, we propose a micro-actuator which can largely improve the capacity and performance of track servo of hybrid recording. The micro-actuator is not executed by normal piezoelectric materials but by rare earth giant magnetostrictive materials such as TbDyFe. Owing to the material's excellent performance, the micro-actuator can work under low voltage driving power conditions, which means that it can be dispense with high voltage driving power which the piezoelectric materials are indispensably, and can move the recording head with very high speed and accuracy. As a result, extremely high data-track density and fast access time can be achieved. The theoretically analysis and computation of the coupling magnetic field intensity of giant magnetostrictive material were carried out. The computation of micro-actuator indicates that there is 0.085μm deformation for a constant magnetic induction of 300mT, and the resulting deformation is a pure bending which corresponds to the real behavior of a thin film actuator.

Phenanthrenequinone-doped poly(methyl methacrylate) (PQ/PMMA) material is considered as one of the ideal optical memory polymer for its negligible volume shrinkage and optional shape. Samples were prepared by modifying the polymerization methods of PQ/PMMA materials in different temperatures and the diffraction efficiency of two-wave mixing was improved. During grating recording process, the maximal diffraction efficiency decreases with temperature increasing in the high-temperature-polymerized sample. For the low-temperature-polymerized sample, the maximal diffraction efficiency increases with temperature increasing at some ranges, and then decreases. Moreover, after the grating set-up, a thermal treatment process caused the diffraction efficiency of the low-temperature-polymerized sample to increase but to decrease for the high-temperature-polymerized sample. The diffusion equation was used to explain the interaction dynamics during the thermal treatment process.

High-density holographic recording parameters changing with the exposure wavelength of a wideband sensitive photopolymer are studied. The results show that the maximum diffraction efficiency, exposure sensitivity, maximum refraction index modulation, dynamic range and the exposure time constant are all incremental with the increase of the exposure wavelength. The analysis indicates that the scattering plays an important role in the phenomenon.

Volume holographic storage is currently the subject of widespread interest as a fast data readout, high-capacity digital data-storage technology. However, due to the effect of cross-talk noise, scattering noise, noise gratings formed during a multiple exposure schedule, it brings a lot of burst errors and random errors in the system. In general, row and column (RAC) array codes is based on single parity check codes, so it is weak to correct errors ability. In order to get the acceptable bit error rate (BER)(10^-12). This paper presents multiblock strategy to solve the application of involving an entire page of data which may be as large as 1Mbits and We design VLSI implementations of multiblock RAC array coding encoder and decoder architecture for volume holographic storage. We analyze performance about hardware requirements and time delays associated with the multiblock RAC array code.

Effects of dyes and initiators in the photopolymer on the holographic storage properties are studied. Diffraction efficiency of photopolymer with Erythrosin B (ErB) as dye is significantly larger than that the same photopolymer with Eosin Y (EY), Rose Bengal (RsB), Rodamine B (RoB) and Fluorescein (F) as dyes under the same conditions. The maximum absorption of ErB is closer to 514nm than the others, and the photobleaching rate constant of the initiating system is higher than the others. Compared with the holographic properties with triethanolamine(TEA) as initiator, diffraction efficiency of the photopolymer with N-phenylglycine(NPG) as initiator is lower, but the photopolymer shows higher stability.

The Volume Holographic Data Storage (VHDS) is an optical technology that allows one million bits of data to be written and read out in single flashes of light. To accommodate the characteristics of VHDS, this paper presents the following strategies in designing the file system based on VHDS: (1) Construct the virtual storage layer on the Holographic Storage media, which turns the storage-on-pages into the storage-on-blocks. (2) Use the two-layer structure of the directory table and the index node, and the data stored in the immediate area of the index node. This method can access the index node and the content (partial or all) of the file with an accessing operation. (3) Adopt the allocating method of the page priority in storing data--allocate the whole page to a file while the length of the file exceeds the page. In the meantime, a page is partitioned into many zones to enhance the storing utilities of VHDS. (4) To meet the three-dimension storage's need, the two-dimension Logical Block Address (LBA) is to be used, and makes the more continuity between data blocks--allocate the continuous data blocks in vertical and horizontal direction while storing data. The simulation test shows that the file system can be compatible with the existing file system, and has better stability.

This paper presents a novel storage architecture called Volume Holographic Universal Storage Cache (for short VHUSC) for the purpose of optimizing disk I/O performance. The main idea of VHUSC is to make use of the Volume Holographic Memory, referred to as VHUSC, as a new layer between main memory and disk. VHUSC can lower the disk access latency, provide much higher I/O bandwidth and throughput. An application independent model based on queuing theory is proposed for performance comparison between VHUSC and traditional disk. The results show performance improvements of up to one order of magnitude.

Zn:Fe:LiNbO₃ crystal has shorter response time and higher damage resistance ability than Fe:LiNbO₃ crystal because of the doping of Zn ions, and the diffraction efficiency in Zn:Fe:LiNbO₃ is comparable to that in Fe:LiNbO₃ crystal. Transmission holographic recording geometry has been taken for its larger attainable dynamic range and sensitivity than that of the 90-degree geometry. Although there is relatively strong fanning effect in transmission geometry, Zn ions in the co-doped Zn:Fe:LiNbO₃ crystal can restrain the fanning effect effectively. In our experiment, 60 holograms were angularly multiplexed and 72 spots were spatially multiplexed without hologram fixing technology, and the holograms can be stored more than ten days. A storage density of 4Gbits/cm³ has been obtained. The whole writing/reading process was accomplished automatically.

We have designed a compact holographic data storage (CHDS) system based on the principle of volume holographic storage and angular multiplexing, using a spherical wave as the reference beam. The CHDS system has large-capacity, high-speed and can retrieve data without changing it, which will provide a revolutionary memory technology. In the experiment, pages of information were recorded and retrieved with the same spherical reference beam. A new method of multiplexing, which is angular multiplexing, furthermore, was developed to maximize the storage capacity, data transfer rate, and minimize the system volume. The main difference between this new method and traditional ones is that we rotate the recording material instead of shifting it. A real experiment system was set up with a volume of 28×18×16cm³ in our laboratory.

Volume holographic digital data storage has many performance characteristics including large storage capacity and high transfer rate. But there are some problems in the commercial applications for holographic digital disc of volume holographic digital data storage. A single beam setup is introduced in this article for holographic digital disc. In this new system, the reference beam and the information beam are coaxially arranged to perform reading and writing. This new single beam setup can reduce the complexity, the demand for mechanical precision, the size and cost of the conventional holographic digital storage setup using dual beams. And it is also compatible with the conventional optical disk technologies.

To test the dynamic photorefractive grating during holographic recording, as usual, the signal wave is blocked from time to time and simultaneously the diffracted beam of the reference wave is tested. This kind of measurement destroys the continuity of the holographic recording and increases the random noise and results in bad repeatability and reliability. In this paper, the phase-conjugate technique is used to overcome the above drawbacks. The reference wave and the object wave are much stronger than the probe beam propagating along the counter-direction of the reference wave. Thus the real-time and non-destructive testing of the dynamic holograms can be obtained by measuring the phase-conjugate wave of the object wave.

Holographic data storage has many advantages, which makes it become one of the most hopeful next-generation data storage techniques. In the past, the struggles of holographic data storage have been frustrated for the absence of suitable system components and recording materials. Recently, the development of practical components for holographic systems, such as SLMs, CCDs and some newly recording materials, has rekindled interest in this technology. In this paper, we analyze the present situation of holographic data storage techniques and some latest improvements of key components and recording materials in relative companies or laboratories are summarized. At last, market outlook of holographic data storage products is discussed.

Multilevel recording has been demonstrated to significantly increase the linear densities achieved with standard methods of binary encoding in optical data storage systems. In this paper we introduce the theoretical concepts and practical coding aspects behind multilevel optical recording system. We show that there are three-stage coding flow and explain how to design and implement the encoder. As an example we give a 5th-power finite state transition diagram of q=8 RLL (2, 10) encoder and compute its adjacent matrix. Especially we discuss the implement method to quickly search decoding table of slider decoder by way of computing the least Hamming distance.

4-Level Run-Length Limited (4L-RLL) optical storage based on photo-chromic materials is firstly investigated in this paper to our knowledge. Unlike binary recording, information in Multi-Level Run-Length Limited (ML-RLL) modulation system is carried in both the amplitude and length of the marks. ML-RLL optical storage can increase the recording density and data transfer rate with no changes to the optical/mechanical unit. For photo-chromic materials, different levels of input laser power amplitude give rise to different reflection levels. Using optimal write strategies, a 4 level linear playback signal was obtained and the sigma-to-dynamic range (SDR) of the 4-level signal was calculated. The results show that the SDR is low enough to provide low bits error rate (BER).

An iterative method designed by angle multiplexing holographic storage is introduced to determine exposure schedule for multiplexing storage in Zn(2mol.%):Fe(0.03wt.%):LiNbO₃ crystal. In this experiment, 60 holograms were recorded in the same location of the crystal with 2mJ/cm² incident exposure energy per hologram (0.7s exposure time at 2.8mW/cm² total incident intensity). And the self-correlation peaks of holograms were collected by CCD. We found that the cumulative grating strength of correlation peak versus exposure energy could be fitted to be a sixth-order polynomial, and made use of an iterative expression to calculate the exposure schedule for 60 holograms. The correlation recognition of 99 pictures with 16 levels gray is completed and the accuracy is 100%, while an appropriate exposure schedule is used to store the two-dimensional holograms.

Multi-level optical storage is a promising approach to increase recording density and data transfer rate significantly without altering optical and mechanical parameters of current optical disc systems. Multi-level amplitude modulation and multi-level run-length limited modulation are two different important recording approaches. In this paper, we discuss and compare these two multi-level modulation principles and corresponding multi-level coding schemes. With advanced coding and signal detection, multi-level run-length limited modulation shows better performances in terms of higher recording density. We present a new 8-ary (1, 3) RLL code constructed by state splitting algorithm for photochromic storage channel. The proposed code has only two coding states and high coding density of 3.0 bits per minimum mark. The encoder/decoder is simple and easy for implementation, which can be applied in future high density multi-level optical storage systems.

Using photochromic diarylethenes as recording media, we performed successfully three-wavelength photon-mode optical storage. Three laser beams of 532, 650 and 780 nm were used in recording and readout simultaneously, and signals with high S/N ratio and no crosstalk were obtained.

A potential application of the novel 4, 4'-bis(diphenylamino-trans-styryl)-biphenyl (BPSBP) for three-dimensional optical data storage by two-photon induced photobleaching was investigated. The fluorescence of BPSBP molecules under two-photon absorption excited by a focused femtosecond(fs) pulsed laser was quenched; therefore, bit data can be recorded by two-photon bleaching in a BPSBP doped Polymethylmethacrylate (PMMA) film and be read nondestructively as darker spots than the non bleaching area emitting fluorescence under low power fs pulsed laser illumination. This enables three-dimensional data recording and reading using a two-photon scanning fluorescence microscope. Experimental results of recording and reading in three layers of three-dimensional data bits with a transverse bit separation of 5μm and an axial layer separation of 8μm (0.5x10¹⁰bits/cm³) were presented, and 10⁷ readout cycles were achieved possibly.

About forty years ago, Ashkin found that the refractive index was changed when laser transmits some materials, then photorefractive (PR) phenomenon was found. During the past four decades, photorefractive nonlinear optics has received great attention due to its real-time operation, high sensitivity, and high holographic storage capacity. The interbeam angle between signal and reference beam usually is large than ten degrees when people storage information, so we can use fundamental photorefractive grating and avoid the influence of higher-order diffraction. However, higher- order diffraction can be used to realize image processing. It has not been well studied because higher-order diffraction images are usually blurry for crystal. With research expanding, photorefractive polymer materials are being paid much attention because of the properties of easy processing, fast response and material flexibility. In this paper, we firstly report some novel photorefractive higher-order diffraction phenomena of polymer material (PVK:5CB:C₆₀ )at small interbeam angle. The photorefractive composite consists of polymer poly[N-vinylcarbazole] (PVK)doped with 4,4, n pentylcyanobiphenyl (5CB) and C₆₀. The weight ratio is 55.45%:44.45%:0.10%(PVK:5CB:C₆₀). The higher-order diffraction images are clear. The experiments testify the feasibility of optical image processing. In two-wave coupling experiments, signal beam is interfered with a mutually coherent reference beam within composites. Results are given respectively when signal beam was focused behind the composites, in front of the composites, in the composites. Higher diffraction order images are amplificatory or inverse. A theory of higher diffraction order images properties in photorefractive liquid crystal polymer composites has been developed. The theory is in good agreement with experimental work.

A D-π-D type compound, 2,7-bis(4-methoxystyryl)-9,9-bis(2-ethylhexyl)-9H-fluorene (abbreviated as MO-Flu-MO), where electron-donor D is methoxy group andπis fluorene unit, has been synthesized. The molecular structures of the compound were characterized by elemental analyses, EI-MS and FT-IR spectra. UV-Vis spectra in the region 230--1000 nm and single-photon excited fluorescence in tetrahydrofuran (THF) of the compound were measured. It is found that the new compound exhibits strong two-photon excited fluorescence in the region 380--500 nm and moderate two-photon absorption (TPA) value in the femtoseconds regime (TPA cross-section as high as 55×10^-50 cm⁴ s photon^-1 with 13fs laser pulses). The results demonstrate that the compound is a promising candidate for two-photon three-dimensional (3D) optical data storage.

Smaller focal points are essential for the development of the next-generation optical disc. The size of focal point depends on the diffraction effect that is dependant on the numerical aperture of a lens and the wavelength of light. However, increase of the numerical aperture and decrease of the light wavelength will be ultimately limited due to the technical difficulty of fabricating a too-high NA lens and the too-short wavelength laser. In this paper, we report another approach of using the superresolution technology to compress the size of the so-called Airy spot for the next-generation optical disc, which is independent on the wavelength of laser. The superresolution phase plates are designed and fabricated with a microoptics technique. When such a phase plate is inserted into the optical system, the central spot at the focal plane of a lens is decreased to be 0.8 times of the Airy pattern, implying the possibility of reading higher storage density of optical discs. The most attractive feature is that the phase plate can be mass-produced at a very low cost, compared with the high cost of the high-numerical lens and/or the short wavelength laser. The disadvantages are that the inserted phase plate will induce the slight circular sidelobes around the central sport, so that it consumes a little more laser energy. The shortcoming could be overcome with suitable amendment. We have fabricated the phase plates with the surface-relief profile on a normal glass for phase modulation. Experimental results of superresolution effect with a low numerical aperture (NA=0.1) and a high-numerical lens (NA=0.8) are reported, which are in good agreement with the theoretical prediction. Superresolution technique should be highly interesting as a novel technique of the next-generation pickup head for reading the high storage of the optical discs.

Super-resolution read-only optical disks using different mask materials and stack structures were prepared by using rf sputtering method, and then dynamic readout properties were measured, our results show that by using Si as the mask material the signal-to-noise ratio can reach about 35dB, and the density can be increased both in the linear direction and in the track direction, while by using AgInSbTe as the mask material the optimum signal-to-noise ratio is about 40dB, which is very close to the practical application level.

We present a new kind of annular beam which consists of two bright rings with asymmetric intensity for increasing three-dimensional resolving capacity of imaging systems. It is shown that by changing the intensity ratio between the two bright rings the distribution of the spatial frequency of the light can be well adjusted and subsequently different superresolution performance including three- dimensional superresolution can be attained. Simulation results have exemplified that with appropriate asymmetric intensity ratio the transverse and axial superresolution can be achieved simultaneously. Moreover, the new annular beam can produce attractively higher Strehl ratio than the tunable leaky pupil under the same three- dimensional superresolution gain.

In this paper, theoretical work on the transmitted-aperture (TA) type super-RENS was introduced. Firstly, the forming of transmitted-aperture in the mask layer was studied based on laser-induced thermal model with Gauss assumption. A numerical simulation was carried out by FEMLAB. The simulation results showed that transmitted aperture would not be formed until the exposure power exceeded a threshold within a certain pulse time and vice versa. Secondly, a calculation model of electromagnetic field of TA type super-RENS disk was presented based on the three-dimensional finite-difference time-domain method (3D-FDTD) together with a vector method of Gaussian beam. Lorenz dispersive model was employed for mask layer and reflective layer. The distributions of electric field for TA type super-RENS were theoretically analyzed. Lastly, the static writing experiment for TA type Super-RENS was carried out with different power and pulse time, as well as for conventional CD-R/W. The experiment results well satisfied the simulation.

Static recording characteristics of super-resolution near-field structure with bismuth (Bi) mask layer and antimony (Sb) mask layer were investigated and compared. The experimental results show that Bi mask layer can also concentrate energy into the center of a laser beam at a low laser energy input similar to Sb, which may be because that Bi film exhibits giant nonlinearity at low laser intensity. The direct observation of laser-recording marks may help better understand the working mechanism of the super-RENS, super-resolution ablation, and other nonlinear switching phenomena.

According to the change of refractive index of Sb thin film with temperature and the radial distribution of temperature within the spot, we can consider the spot irradiated by a Gaussian beam as a phase-modulated screen. Based on Fresnel-kirchhoff diffraction theory, a Gaussian diffraction model which can compute the intensity from far field has been set up. Using this model we can study the nonlinear change of mask layer samples induced by different reasons. A numerical calculation of the transmittance through an Sb-type super-resolution near-field structure was carried out as an example. The Gaussian diffraction model, which is similar to the far field detection process in the optical disk system, is very useful for analyzing the photothermal-induced local structure change of thin films in phase-change and super-resolution optical disks.

A novel metallized azo dye has been synthesized and its thin film on K9 glass has been prepared. The absorption spectra, thermal character and static optical recording properties with Bi mask layer super-resolution near-field structure (Super-RENS) of the dye were investigated. The results show that the dye film has a broad absorbance band in the region of 450-650nm and the maximum absorbance wavelength is located at 603nm, which is red shifted 17nm comparing with that of its chloroform solution, a steep absorbance falling edge in 603-650 is observed. It is found that the new metallized azo dye occupies excellent thermal stability, initiatory decomposition temperature is at 270°C and the mass loss is about 48% in a narrow temperature region (15°C). Static optical recording tests with and without Super-RENS were carried out using a 650nm semiconductor diode laser with recording power of 7mW and laser pulse duration of 200ns. The AFM images show that the diameter of recording mark on the dye film with Bi mask layer is reduced about 42% comparing with that of recording mark on the dye film without super-resolution near-field structure. It is indicate that Bi can well performed as a mask layer of dye recording layer and the metallized azo dye can be a promising candidate for recording medium with super-resolution near-field structure.

Kinetic properties of non-equilibrium phase transition of solid state system have been simulated using the spreadsheet program. The amorphous phase translates explosively into the crystalline phase when the excited cell is surrounded by more than the critical number in crystalline cells. Some parameters such as critical number and energy have been revealed to control the transition rate, transition region and phase distribution. The cellular automata, in this way, give many aspects to the characteristics of the explosive crystalline phase transition and the spreadsheet provides us powerful and simple circumstances to these kinds of simulations.

Crystallization was induced in amorphous Ge₂Sb₂Te₅ and AgInSbTe films by femtosecond laser with an average power of 20mW at a frequency of 1 kHz and a pulsed width of 120 fs. Transmission electron microscopy observes the morphology of Ge₂Sb₂Te₅ and AgInSbTe films before and after irradiation of femtosecond laser pulses and confirms the existence of crystalline state.

High-density Optical storage technology which uses a 405 nm laser and an objective lens of high numerical aperture (NA)of 0.85 is developing rapidly due to its high capacity over 23 GB on a single layer of a 120mm-diameter optical disc and great commercial demands. New storage media have been the bottleneck in high density optical storage. Organic material can be an attractive optical storage medium with various advantages, such as good sensitivity, easy fabrication, reasonable cost and structural flexibility, etc, compared with inorganic storage material. Efforts have been made to seek for new organic storage materials with high performance matching the 405 nm short wavelength laser. In this paper, recent progresses in developing organic materials as recording media for high density blue laser optical storage are presented. The recording mechanism of recordable dye layer and basic requirements for the dye materials are analyzed and discussed.

A novel naphthalimide dimer tethered by photochtomic bisthienylethene-bridge was syhthesized by Suzuki coupling method as potentially all photo-mode memory media and fluorescent molecular switch. Bisthienylethene-bridged naphthalimide (BTE-NP) dimer reversibly changed the fluorescence intensity by alterative irradiation with ultraviolet and green visible light probably due to the fluorescence resonance energy transfer (FRET) from naphthalimides to the closed form of bisthienylethene moiety. All compounds were characterized by ¹H NMR spectra and mass spectra etc. The spectroscopic properties including the fluorescence lifetime and photochromic quantum yields of BTE-NP were also measured.

Thin film of a novel charge-transfer complex CuTCNQ derivative was prepared by spin-coating. Experimental results of this film for red-light rewritable optical storage are as follows: writing power13mW, writing pulse duration 200ns; erasing power 3mW, erasing pulse duration1000ns; reflectivity contrast C is greater than or equal to 27%; numbers of write-erase cycle N is greater than or equal to 1000.

The photochromic diarylethene, 1,2-bis(2-methyl-5-methylene-n-butylamido-thien-3-yl)perfluorocyclopentene (BMMBTP), was synthesized and its photochromic and fluorescence properties was investigated. This compound underwent a photochromic reaction both in solution and in PMMA amorphous film. Using diarylethene-PMMA amorphous film as memory medium, we firstly performed successfully two-photon 3D optical storage.

A novel asymmetric photochromic compound [1-(2-methyl-5-formyl-3-thienyl)-2-(2-methyl-5-phenyl-3-thienyl)] perfluorocyclopentene (1a) was synthesized and its photochromic and electrochemical properties were investigated. Dithienylethene 1a changed the color from colorless to blue upon irradiation with 254 nm UV light in hexane solution and in PMMA, in which absorption maxima were observed at 590 nm and 604 nm, respectively. Electrochemical reduction of 1a results in the blue ring-closed (1b) by cyclic voltammetry test.

A novel photochromic dithienylethene, [1-(2-methyl-5-formyl-3-thienyl)-2-(2-methyl-5-naphthyl-3-thienyl)]perfluoro- cyclopentene (1a), was synthesized and its photochemical properties, such as photochromism in solution as well as in poly-methylmethacrylate (PMMA) amorphous film, fluorescence were investigated in detail. Dithienylethene 1a has shown good photochromic behavior both in solution and in PMMA film. Upon irradiation with 254 nm UV light, its color changed from colorless to blue, in which absorption maxima were observed at 584 nm in hexane and 596 nm in PMMA film. 1a also showed relatively strong fluorescence in different solvents when excited at 292 nm. In addition, photon-mode holographic optical storage using dithienylethene 1b as recording medium was performed successfully.

A fluorene derivative having two diarylethene units at the 9,9'-positions was synthesized, and the photochromic behavior was examined in solution. Upon irradiation with UV (240nm), the solution of the diarylethene dimer turned yellow. It can returned to ring-open form upon irradiation with visible light (405nm). Two diarylethene chromophores are connected to the fluorene without π-conjugation between them in the dimer. Its synthesis can be performed on a large scale from cheap commercial products and no expensive drugs were concerned in the synthetic route.

Two novel photochromic diarylethenes, 1,2-bis-[2-methyl-5-(4-formylphenyl)-3-thienyl]perfluorocyclopentene (1a) and 1,2-bis[2-methyl-5-(p-fluorophenyl)-3-thienyl]perfluorocyclopentene (2a), were synthesized and their photochromism and dynamics of the ring opening and closure reaction both in solution and in PMMA film were investigated. The results showed that 1a and 2a changed the color from colorless to blue upon irradiation with 313 nm UV light, in which absorption maxima were observed at 600 and 572 nm in hexane and at 612 and 588 nm in PMMA film, respectively. Their cyclization/cycloreversion processes were zeroth and first order reaction both in solution and in PMMA film, respectively.

Five diarylethenes which have similar absorption spectra were chosen as recording media and their writing/readout characteristics were investigated in photon-mode optical storage. Writing power and the recording laser wavelength were the main factors influencing writing time. The experimental results showed that the writing time decreased rapidly with the increases of writing power (P), and the destruction of the readout had a remarkable difference when recording on the left side of the their maxima absorption with a 532 nm laser and recording on the right side with a 650 nm laser. The readout destruction of recording at the left side was much smaller than that of recording at the right side.

Metal-azo complex is a new class of optical strorage medium and nonlinear optical material. The complex refractive indices N(N=n-ik), dielectric constants ε(ε=ε₁-iε₂), and absorption coefficients α of four kinds of novel azo dyes based on 4-methylthiazole, 5-methyl-3-isoxazole spin-coated thin films are determined from an scanning ellipsometer in the wavelength 400-700nm region. The molecular structural relationships on optical constants of metallized azo dyes were investigated. Metal chelation strongly (about one times) enhances the optical constants at the peaks and results in large bathochromic shift (ca.60-70nm) of absorption band. Bathochromic shift of Ni-azo complex is about 10nm larger than that of Zn-azo complex due to different spatial configurations formed in the metal-azo complexes. Meanwhile, the diazonium components of azo dye also affect the optical constants and maximum absorption.

Three kinds of novel metallized azo dyes based on 4-methylthiazole, 5-methyl-3-isoxazole and 5-methyl-1,3,4-thiadiazole were synthesized in order to obtain a suitable optical recording medium for digital versatile disc-recordable(DVD-R). The absorption spectra, optical constants and thermal decomposition as well as red-light (650nm) static recording properties of three nickel-azo dye films were investigated. Particularly, the nickel-azo dye film based on 5-methyl-1,3,4-thiadiazole, peaking at 554nm and 602nm, with higher refractive index (n=2.41) and lower extinction coefficient (k=0.042) at the wavelength 650nm and a sharp threshold of thermal decomposition at 335°C was obtained. The results of the red-light(650nm) static optical recording test of this dye film indicated that higher reflectivity contrast of 35% can be obtained at a laser writing power of 7.5mW and pulse width of 200ns. These results imply the nickel-azo dye based on 5-methyl-1,3,4-thiadiazole is a promising candidate as a recording medium of DVD-R.

Three kinds of novel rare earth metal β-diketone bipy complexes have been synthesized. Smooth films of the complexes on K9 glass substrates and single-crystal silicon substrates were prepared by spin-coating method. The absorption spectra of these new materials were measured in solution and in film. The optical constants (complex refractive index N=n+ik ) of the films on single-crystal silicon substrates at 405nm were determined with scanning ellipsometer. The thermo-gravimetric analysis (TGA) of the materials was also carried out. It is found that the absorption spectra of these films have comparatively broad band in the wavelength region 300-400nm, the peek is at ~345nm and the absorption edge is steep in the wavelength region 350-400nm, which indicates that the absorption of the films is well matched with the wavelength of GaN semiconductor laser diode (405nm). The refractive index (n) of the films is above 1.9 and the extinction coefficient (k) of is 0.1-0.3 at 405nm. The reflection peeks are located near 405nm. And also the new materials possess excellent thermal stability (their decomposition temperatures are higher than 300°C). The results imply that these novel materials are promising candidates for the recording media of blue discs.

As the digital TV(DTV) technologies are developing rapidly on its standard system, hardware desktop, software model, and interfaces between DTV and the home net, High Definition TV (HDTV) program worldwide broadcasting is scheduled. Enjoying high quality TV program at home is not a far-off dream for people. As for the main recording media, what would the main stream be for the optical storage technology to meet the HDTV requirements is becoming a great concern. At present, there are a few kinds of Post-DVD formats which are competing on technology, standard and market. Here we give a review on the co-existing Post-DVD formats in the world. We will discuss on the basic parameters for optical disk, video /audio coding strategy and system performance for HDTV program.

Blu-ray Disc format is required by the forthcoming of High Definition TV era which calls for a brand new generation of optical storage after DVD. It is such a technology with wavelength short as 405nm and numerical aperture high as 0.85. The format is designed to have an even wider disc tolerances than those of DVD. Thanks for those more innovative concepts Blu-ray Disc is the most economical storage solution in terms of cost per giga byte. And it is expected to be a long-term optical storage standard rather than an interim solution.

Blu-ray Disc (BD) is the next generation optical disc format, currently being standardized by a large consortium of leading CE, PC, authoring companies and major movie studios. BD offers more than five times the capacity of DVD at 25 GB and 50 GB (dual layer). The BD application format addresses the limitations of DVD-Video by providing a complete user experience. The high storage capacity guarantees the best quality HD video available to the consumer. BD standardizes how content publishers can include executable applications on the disc to realize fully enhanced interactivity. By using a programming platform like Java, the standard need not define the allowable set of features, instead it defines the playback platform and disc publishers are free to implement any features they desire. Furthermore, BD supports seamless integration of Internet content with disc content, allowing synchronized presentation of updated content from the Internet with disc content. With this combination of features, highest quality HD video, enhanced interactivity and Internet connectivity, BD offers consumers a compelling experience. This paper will present an overview of the features that will be supported by the BD application format and the technical solutions used to realize these features.

There are many proposals and studies for the high density optical data storages with a data capacity over 150GB. Multi-layer recording is consider as one of the best candidates for the next generation optical data storage since it can be realized with an addition of a few optical components in the current Blu-ray (BD) optical pickup. Of course, it is required to compensate the spherical aberration between the recording layers in the multi-layer disk. A novel liquid crystal (LC) lens is proposed and designed to compensate the spherical aberration occurred by the difference of substrate thickness. New structure of liquid crystal (LC) lens includes both concave and convex surfaces which can compensate the spherical aberration with a relatively long range. Since previously developed LC panel showed very low tolerance to the shift of objective lens, new design was proposed with a special LC lens structure to improve both characteristics of the shift tolerance and compensation range. The refractive index of LC lens is changed by applying a voltage on the ITO electrodes prepared with a curvature surface. Therefore, a focal point of the transmitted light can be changed with a careful control of applied voltage, resulting in a compensation of the spherical aberration. Several types of LC lens, including spherical and aspherical surfaces, were designed and their performance was simulated theoretically. With an optimized curvature control with the spherical LC lens, the aberration of BD optical pickup can be kept under 0.018λRMS even for the thickness variation of ±25μm.

Measurement technology plays an important role in the research of optical storage. Aiming at constructing research platform for blue-ray optical data storage, we designed and built a modularized static testing system, in which laser wavelength is 406.7nm. Modulation/demodulation technique is employed to weaken the test noise. The focus move mode decreases the requirement in size of samples. And Piezoeletronic nano-positioner is used to facilitate the relocation of recording marks and improve test repeatability. Experimental results are also given to verify the performance of the static testing system.

In this paper we describe the liquid immersion mastering technique and its application to the mastering of ROM discs for the Blu-ray Disc system and for ROM discs with considerably higher data densities. Replicated 25GB BD-ROM discs were evaluated using a standard blue test player (λ=405nm, NA=0.85). A bottom jitter value with limit equalizer of less than 5% was measured. Also the values of asymmetry, normalized push pull and symbol error rate were well within the Blu-ray Disc format specification, offering a large process window. Full-format BD-ROM test discs with high definition video content were mastered and their successful read-back was demonstrated. In addition we show that liquid immersion mastering can successfully be applied for mastering of considerably higher densities. Measurements on replicated discs up to data densities above 40GB per layer are discussed. The present results demonstrate that liquid immersion mastering is a proven technology for the mass-production of high data capacity ROM discs.

It is well known that the optical pick-up (OPU) plays a very important role in optical storage system. And the quality of OPU can be measured by the characteristics of OPU read-out spot for high density optical storage. Therefore this paper mainly designs an OPU model for high density optical storage to study the characteristics of OPU read-out spot. Firstly it analyses the optical read-out principle in OPU and contrives an optical read-out system based on the hereinbefore theory. In this step it chiefly designs the grating, splitter, collimator lens and objective lens. Secondly based on the aberrations analysis and theory involved by the splitter, the collimator lens and the optical lens, the paper uses the software CODE V to calculate the aberrations and to optimize the optical read-out system. Then the author can receive an ideal OPU read-out spot for high density optical storage and obtain the characteristics of the ideal OPU read-out spot. At the same time this paper analyses some influence factors which can directly affect the characteristics of the OPU read-out spot. Thirdly according to the up data the author practically manufactures a real optical pick-up to validate the hereinbefore designed optical read-out system. And it uses the Optical Spot Analyzer to get the image of the read-out spot. Comparing the ideal image to the actual image of the designed optical read-out system, the author finds out that the upwards analyses and design is suitable for high density storage and can be used in the actual production. And the author also receives the conclusion that the mostly influences on characteristics of OPU read-out spot for high density optical storage factors is not only the process of designing the grating, splitter, collimator lens and objective lens, but also the assembling work precision

The key to control the disc quality is to find the relationship between process parameters and the disc electrical capabilities. This is done in two steps: first step is from process parameters to physical parameters, second step is from physical parameters to electrical parameters. While the first step is based upon test experiments and process analysis, the second step is based upon simulation. In this paper, we apply a simulation model to determine electrical parameters from measured physical parameters of a recordable disc before recording and after recording. Further, we extend the model on dual-layer DVD-R disc.

Our investigation covers the BD ROM as well as BD RE (re-writable) substrates moulding process. We performed series of experiments investigating and optimising the moulding process for BD substrates. The relations between the mould temperature, cycle time, moulding process, cooling pulses and the physical properties of the substrates itself were investigated. Several relations are presented for dependence of the substrates physical parameters like birefringence, tangential and radial deviation, diffraction efficiency, AFM measured groove/pit geometry. It was shown that comparing to the stationary type of cooling, the Pulsed Cooling method of moulding the BD discs manufactures substrates with lower birefringence, tilt, dishing, very good groove/pit replication quality with shorter cycle time and using the lower mould temperature. Optimized moulding process conditions are indicated.

We examine a lifetime estimation method for high-density recordable optical disks. It is based on the Eyring acceleration model and statistical analysis. The statistical distribution of life data for the optical disk assumed a lognormal distribution. The standardized life expectancy of an optical disk is defined as the minimum lifetime of 95% survival probability at 25°C / 50%RH with a 95% confidence level. An acceleration test was conducted under stress conditions of temperature and relative humidity. Results have demonstrated that the statistical distribution of lifetime data using the digital error criterion item can be applied to a lognormal distribution. Thereby, we can estimate a standard life expectancy of high-density recordable optical disks as the minimum lifetime of 95% survival probability at a 95% confidence level.

The optical systems using the probe and solid immersion lens (SIL) have been researched as the technology to embody the near field recording (NFR) system. In NFR system, it is very important for the clearance between slider and disk surface to remain under 100nm in order to use effect on evanescent wave. The OFH should also have a small pitch to control the contamination effect. Because the larger the gap between leading edge of slider and disk is, the more particles come into SlL. As a result, they have a lot of bad influence on SIL. However, the flying stability turns bad as the pitch angle becomes small. Accordingly, it is necessary to consider dynamic characteristics in OFH ABS design. This research made two approximation models through the regression analysis and neural network, which are the parameter analysis based on optimization techniques. This study also used micro-genetic algorithm (GA) and design optimization tool (DOT). ABS shape of flying head was optimized with the object of remaining FH of several ten nano meter in static state. And the dynamic optimization was carried out toward decreasing FH modulation. As a result of static optimization, the flatness of flying height was restricted within 1% in inner diameter (ID) and outer diameter (OD). Besides, the flying height was remained about 50nm. In the dynamic optimization, the vertical sensitivity of dynamic optimal model was bigger than that of original model and the pitch sensitivities was also improved a bit.

The Blu-ray Disc (BD), which achieves approximately five times the recording density as that of a DVD, employs 1-7PP encoding, a more efficient encoding method than EFM+ modulation (8-16) of DVD. The shortest mark length recorded by this method is 2T (approximately one-third of the length) as compared to 3T of a DVD (where T is the channel clock period). Because it is difficult to reproduce such high-density signal using binarized decoding, Partial Response Maximum Likelihood (PRML) is often used in its place. Jitter, which has been used as a reference in the evaluation of the reproducing signal of DVDs, does not necessarily match the bit error that results from PRML decoding. Consequently, BD which heavily uses PRML decoding requires a new evaluation method that replaces the conventional method using jitter evaluation. Because the correlation between the jitter and bit error is worse when the jitter of the 2T mark is predominant among all mark jitters, we focused our attention to jitters that exclude the jitter of the 2T mark as a reference for evaluating the S/N ratio of the system directly through the use of the inter-symbol interference analysis function of the time interval analyzer. This paper describes the analysis of the correlation between jitters that exclude the jitter of the 2T mark and the bit error rate.

As a popularity of a portable digital device such as a cellular phone, a digital camera and a MP3 player is spreading, the demand of the mobile storage device increases rapidly. A Blu-ray technology using 406nm laser diode and 0.85 NA(Numerical Aperture) satisfies a miniaturization and a high capacity which are the requirements of the portable device. Because a Blu-ray optical storage device can store 1.5Gbyte on a 3cm disk, it is possible to distribute the media in great quantities and with cheaper price. In this paper, we analyze the optical performance of the hybrid micro lens which is manufactured using a micro fabrication technology. The measurements of the optical power, the spot size and the wavefront error are performed to evaluate the hybrid micro lens with 0.85 NA and the designed wavelength of 406nm. Using the measured data, we estimate if the performance of hybrid micro lens corresponds to the designed performance. Also, the processes of measuring an optical performance of hybrid micro lens, which is composed of the refractive lens and the diffractive lens, are proposed using laser diode of 406nm and finite optics.

Digital TV is now being enhanced with interactivity based on such standards as Multimedia Home Platform (MHP) and Digital TV Application Software Environment (DASE). However, recording interactive DTV programme is not that straightforward as it seems. The user will expect the interactivity to still be accessible when a recorded programme is played back from storage. Due to the complexity of the iTV broadcasting, there are many problems for recording interactive TV programme. In this paper we analyze the MHP transport stream structure, describe the recording solution and storage format. Implementation system examples both for recording and playing back are depicted as well.

The optical disk drive with more robustness against shock has been rarely studied. This research shows the shock response analysis of conventional optical disk drive. Main base of the optical disk drive is described with the motion of bouncing, pitching, and rolling. The entire model includes pick-up actuator. Finite element model of the entire system is made by ANSYS. And the lumped parameter model is made, which will replace the finite element model. Shock response of finite element model is compared with that of the lumped parameter model. Their shapes and magnitudes are the same. Therefore, the lumped parameter model can replace the finite element model. The lumped parameter model has advantages of cost and time over the finite element model. Linear drop test and tilt drop test are made in order to verify our shock model. Accelerometer is used for detecting input acceleration. Laser Doppler vibrometer is used for measuring the motion of the main base and pick-up actuator. Then experimental result is compared with the shock response of lumped parameter model. Their shapes are much the same. Therefore, the lumped parameter model of the optical disk drives can represent the real system.

Based on the focus pre-search a method is presented to measure the characters of the traverse focus error detection system. In the pre-search of traverse focus servo system, the traverse focus offset is measured by the focus error occurring time, and the traverse focus error sensitivity and linear range are measured by the focus error slope and peak-to-peak value. A traverse focus error detection system is measured. The results show that the traverse focus offset is too high to stable the focus servo.

Phase locked loop (PLL) is a closed loop automatic control system, which can track the phase of input signal. It widely applies in each area of electronic technology. This paper research the phase locked loop in optical memory servo area. This paper introduces the configuration of digital phase locked loop (PLL) and phase locked servo system, the control theory, and analyses system's stability. It constructs the phase locked loop experiment system of optical disk spindle servo, which based on special chip. DC motor is main object, this system adopted phase locked servo technique and digital signal processor (DSP) to achieve constant linear velocity (CLV) in controlling optical spindle motor. This paper analyses the factors that affect the stability of phase locked loop in spindle servo system, and discusses the affection to the optical disk readout signal and jitter due to the stability of phase locked loop.

As the executive part, the actuator of optical pick-up (OPU) accomplishes the servo action actually. The dynamic characteristics of the OPU actuator determine the precision of focusing and tracking servo system, so it will influence the reading performance of optical pick-up. As the density of optical storage increases, the OPU actuator has a high servo bandwidth for its focusing and tracking control to follow dynamic disturbances by high density and high rotational speed of disk. The dynamic response curve should be as smooth as possible in its linear area. In this paper, the influence of the rolling of moving part on the actuator's dynamic characteristics is studied. Because of some design reasons, the moving part of the actuator may roll in three dimensions during the working status. It's one of the most important factors to influence the dynamic characteristics of actuator. Firstly, the reason of rolling and the influence on dynamic characteristics are studied. In the design of actuator we should pay attention to three important points, which are the gravitational point, the equivalent driving force point and the equivalent sustained point. When the three points are not accordant during the moving action, the rolling occurs. The dynamic response curve will have some unexpected resonances at certain frequency area. This phenomenon is analyzed by kinetic method. Secondly, a model of the actuator is founded referring to an actual type of actuator. By finite element analysis software (ANSYS), the mechanical and magnetic simulation is performed. The special distributing of electromagnetic field is described and the driving force is analyzed. Thirdly, the dynamic characteristics of some actuators with rolling are tested. The experimental result is consistent with the simulation result. So the validity of this study is verified. At last, the possible methods to avoid rolling of moving part are introduced.

We report a method for testing small light spot produced by an optical system with high numerical-aperture (NA). A high NA objective was used to converge the incident linear polarized light, and a tapered optical fiber probe with an opening of 50-80 nm mounted in the near-field optical microscopy (SNOM) apparatus was used to measure light intensity. The small light spot can be measured with high spatial resolution. The results show that a resolution of 50~100 nm can be obtained.

The paper describes a kind of fibre channel RAID that support multiple protocol disk interfaces. It can manage many kinds of disk storage devices with different physical interfaces in the same time, and it can bind different kinds of disks in one logical RAID group. The interfaces can be parallel SCSI, SATA, FC, SAS, iSCSI and etc. So it can help to consolidate enterprise storage, and reduce storage management cost. The fibre channel RAID comprises of SCSI target, SCSI initiator, RAID kernel and management modules. It implements target-mode fibre channel protocol that decides the host interface type of RAID in SCSI target module. The SCSI initiator module includes SCSI initiator mid-layer(SIML), SCSI front-end initiator drivers(FEIDs). There are many kinds of disk interfaces, but the disk devices using different protocol can understand the same block level access protocol such as the traditional parallel SCSI. So we encapsulate all the common processing operations of SCSI commands and responses in one SIML. And we implement specific SCSI transport protocol in one FEID, which supports a specified kind of disk interface. In the SCSI initiator module, there can be more than one FEID. It can bring SATA, parallel SCSI, fibre channel and other kind of disks into SAN environment in the same time. It can accelerate storage consolidation, and reduce storage management cost.

CD mirror system can separate the reading from storing of CD information, enabling user to share CD resource with higher speed. Existing remote CD mirror system is generally based on NAS mode. NAS-based device accesses the data at file level and the data must pass through the file system layer, increasing the system burden; iSCSI system encapsulates SCSI commands over IP, which just corresponds with the transport mechanism of remote CD mirror system. Therefore, in this paper we have implemented a new remote CD mirror system by introducing iSCSI protocol and third-party transferring mode. With third-party transferring mode data information and control information are transferred independently, the data information is transferred by iSCSI protocol, and control information is transferred by TCP/IP protocol, so as to increase the network transfer rate. The result of experiment has showed that the CD mirror system can achieve higher data transfer rate and support more concurrent sessions relative to existing systems, and have better scalability using third-party transferring mode.

Storage demands are growing rapidly with the increasing usages of multimedia, stream casting, and large scale database. High-performance RAID storage is a critical component for many large-scale data-intensive applica¬tions. The goal of our project is to implement high performance external RAID controller based on Intel IOP321. The software design of the RAID controller is introduced, which consists of six functional modules: SCSI Target, Cache Management, RAID Kernel, I/O Schedule, SCSI Initiator and Global Configuration. A PC architecture RAID controller with Fibre Channel interface to host has been implemented to test algorithms and evaluate performances. We also present hardware scheme of the controller based on Intel IOP321 processor.

With the increasing of CD data in internet, CD mirror server has become the new technology. Considering the performance requirement of the traditional CD mirror server, we present a novel high performance VCL (Virtual CD Library) server. What makes VCL server superior is the two patented technologies: a new caching architecture and an efficient network protocol specifically tailored to VCL applications. VCL server is built based on an innovative caching technology. It employs a two-level cache structure on both a client side and the server side. Instead of using existing network and file protocols such as SMB/CIFS etc that are generally used by existing CD server, we have developed a set of new protocols specifically suitable to VCL environment. The new protocol is a native VCL protocol built directly on TCP/IP protocol. VCL protocol optimizes data transfer performance for block level data as opposed to file system level data. The advantage of using block level native protocol is reduced network-bandwidth requirement to transfer same amount of data as compared to file system level protocol. Our experiment and independent testing have shown that VCL servers allow much more number of concurrent users than existing products. For very high resolution DVD videos, VCL with 100Mbps NIC supports over 10 concurrent users viewing the same or different videos simultaneously. For VCD videos, the same VCL can support over 65 concurrent users viewing videos simultaneously. For data CDs, the VCL can support over 500 concurrent data stream users.

The network-attached optical disk storage system has the advantages of the network-attached storage system and the optical storage device. Due to the data reliability and the removability of the storage medium, this optical storage system is very effective on massive data providing and backup. Recently, achievements have been made in security models and policies in a distributed network system environment and the network-attached storage system environment. However, the relevant research is not enough in the network-attached optical disk storage system, especially in a network-attached optical disc device. So it is significant to analyze the security policy and setup a good security model for the network-attached optical disk storage system. This paper makes a theoretical analysis on the security policy in the network-attached optical disk storage system. Firstly, the difference of the network-attached optical disk storage system and the distributed network system environment is presented. The network-attached optical disk storage system is a special distributed network system, and to meet the requirements of the system security, we use the authentication and key exchange protocol method to decide who is authorized to have what access rights on which objects with respect to some security models and policies in compute system. Secondly, we compare the effect of several types of authentication and key distribution protocols in a distributed network system environment. Then we port these authentication and key exchange protocols on the network-attached optical disk storage system environment. Based on these analyses, this paper proposes a secure key management scheme for security services in the network-attached optical disk storage system over open networks. This scheme focuses on the framework for authentication and the centralized key management, and future work will focus on dynamic membership management.

Diarylethene is one of photochromic material with many advantages and one of the most promising recording materials for huge optical data storage. Diarylethene has two forms, which can be converted to each other by laser beams of different wavelength. The material has been researched for rewritable optical disks. Volatile data storage is one of its properties, which was always considered as an obstacle to utility. Many researches have been done for combating the obstacle for a long time. In fact, volatile data storage is very useful for anti-piracy optical data storage. Piracy is a social and economical problem. One technology of anti-piracy optical data storage is to limit readout of the data recorded in the material by encryption software. By the development of computer technologies, this kind of software is more and more easily cracked. Using photochromic diarylethene as the optical recording material, the signals of the data recorded in the material are degraded when it is read, and readout of the data is limited. Because the method uses hardware to realize anti-piracy, it is impossible cracked. In this paper, we will introduce this usage of the material. Some experiments are presented for proving its feasibility.