This PDF file contains the front matter associated with SPIE Proceedings Volume 10384, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Internet of Things (IoT) is a network of interrelated physical objects that can collect and exchange data with one another through embedded electronics, software, sensors, over the Internet. It extends Internet connectivity beyond traditional networking devices to a diverse range of physical devices and everyday things that utilize embedded technologies to communicate and interact with the external environment. The IoT brings automation and efficiency improvement to everyday life, business, and society. Therefore IoT applications and market are growing rapidly. Contrary to common belief that IoT is only related to wireless technology, optical technologies actually play important roles in the growth of IoT and contribute to its advancement. Firstly, fiber optics provides the backbone for transporting large amount of data generated by IoT network in the core , metro and access networks, and in building or in the physical object. Secondly, optical switching technologies, including all-optical switching and hybrid optical-electrical switching, enable fast and high bandwidth routing in IoT data processing center. Thirdly, optical sensing and imaging delivers comprehensive information of multiple physical phenomena through monitoring various optical properties such as intensity, phase, wavelength, frequency, polarization, and spectral distribution. In particular, fiber optic sensor has the advantages of high sensitivity, low latency, and long distributed sensing range. It is also immune to electromagnetic interference, and can be implemented in harsh environment. In this paper, the architecture of IoT is described, and the optical technologies and their applications in the IoT networks are discussed with practical examples.

Launched in November 2015 by the National Science Foundation, the four Regional Big Data Innovation Hubs (Northeast, Midwest, South, and West) build and strengthen public-private partnerships to address societal challenges. Focus areas include Smart Cities / Metro Data Science, Precision Medicine, Natural Resources and Hazards, and Education. By convening stakeholders from academia, industry, nonprofits, and government, the Big Data Innovation Hubs help the community to identify collaboration opportunities, share best practices, and advance the implementation of big data technologies. This talk will introduce the flagship initiatives of the West Big Data Innovation Hub, describing a series of projects and applications that could leverage next-generation optical data storage systems. Design issues including the integration of hardware, software, and human-computer interaction elements will be discussed, emphasizing practical testbeds and pilot projects that bridge sectors and spark community engagement.

The field, IoT and Big data, which is activated by the revolution of ICT, has caused rapid increase of distribution data of various business application. As a result, data with low access frequency has been rapidly increasing into a huge scale that human has never experienced before. This data with low access frequency is called “cold data”, and the storage for cold data is called “cold storage”. In this situation, the specifications of storage including access frequency, response speed and cost is determined by the application's request.

Previously, we proposed and experimentally demonstrated enhanced recording speeds by using a resonant optical cavity to semi-passively increase the reference beam power while recording image bearing holograms. In addition to enhancing the reference beam power the cavity supports the orthogonal reference beam families of its eigenmodes, which can be used as a degree of freedom to multiplex data pages and increase storage densities for volume Holographic Data Storage Systems (HDSS). While keeping the increased recording speed of a cavity enhanced reference arm, image bearing holograms are multiplexed by orthogonal phase code multiplexing via Hermite-Gaussian eigenmodes in a Fe:LiNbO3 medium with a 532 nm laser at two Bragg angles for expedited recording of four multiplexed holograms. We experimentally confirmed write rates are enhanced by an average factor of 1.1, and page crosstalk is about 2.5%. This hybrid multiplexing opens up a pathway to increase storage density while minimizing modifications to current angular multiplexing HDSS.

The cavity supports the orthogonal reference beam families as its eigenmodes while enhancing the reference beam power. Such orthogonal eigenmodes are used as additional degree of freedom to multiplex data pages, consequently increase storage densities for volume Holographic Data Storage Systems (HDSS) when the maximum number of multiplexed data page is limited by geometrical factor. Image bearing holograms are multiplexed by orthogonal phase code multiplexing via Hermite-Gaussian eigenmodes in a Fe:LiNbO3 medium with a 532 nm laser at multiple Bragg angles by using Liquid Crystal on Silicon (LCOS) spatial light modulators (SLMs) in reference arms. Total of nine holograms are recorded with three angular and three eigenmode.

Holographic data storage is a data storage with large data amount recorded by volume holography. Holography is well known as a method to record three-dimensional scenes. The principle is roughly established and major characteristics are well understood. In the case of three-dimensional scenes, some noises are acceptable because they are compensated by our brain. However, in the case of holographic data storage, the recording images are minute two-dimensional coded patterns so that the images are not robust for noises. Therefore, rigorous expressions of recording signal is required. In this study, the recording signal wave is expressed by Taylor expansion for small argument and asymptotic expansion for large argument. Then, the filling factor of pixels in a spatial light modulator (SLM), the size and the position shift of a rectangular aperture at a Fourier plane are considered. When the signal wave is ideally reconstructed, the signal wave at an image plane is captured by using an image sensor. Then, the signal wave is integrated by the area of pixels in the image sensor. In this study, the integral is analytically calculated whereas it is numerically calculated in general because the signal wave is expressed by analytic functions. Therefore, interpixel crosstalk is easily evaluated. In our previous study, high-density recording method of binary data pages is proposed by using four-step phase mask. The high-density recording characteristics are evaluated by analytic functions. When parameters such as the filling factor of pixels in a SLM and an image sensor and the size and the position shift of a rectangular aperture can be known, the analytic functions are obtained. Then, the analytic functions are expected for error corrections.

Publisher's Note: This conference presentation was withdrawn 15 January 2018 per author request.

In microholographic recording, temperature change causes the thickness and refractive index change of the recording medium, which lead to the decrease in the diffraction efficiency of a microhologram due to the Bragg mismatch. Therefore, the effect of the temperature change in the microholographic recording and its compensation method were investigated through a numerical simulation. The wavelength of the laser was 405 nm and the numerical aperture of the objective lenses was 0.85. The thickness change ratio and refractive index change of the recording medium due to the temperature change were 5.0 × 10^-4 / deg. and −3.0 × 10^-4 / deg., respectively. The diffraction efficiency of the microhologram was calculated using the coupled wave theory. The tolerance of the temperature change increased from ±1.8 deg. to ±12 deg. with the compensation by the wavelength change of the laser. However, the width of the readout signal after the compensation increased with the temperature change in both the in-plane and vertical directions. In the microholographic recording, the beam consists of multiple plane waves and the microhologram consists of multiple diffraction gratings. At the center of the beam, the corresponding wave vector of the plane wave and grating vector of the diffraction grating are perpendicular to the recording medium. On the other hand, at the periphery of the beam, they are slanted to the recording medium. Therefore, the Bragg matching conditions at the center and periphery of the beam are different from each other. The above results are attributed to this fact.

Polarization holography is the coherent interference of the beams that can have the different polarized states. The early-stage theory of polarization holography is based on Jones matrix, where the paraxial approximation is assumed, while the theory of polarization holography represented by dielectric tensor can describe the case with a large crossing angle. And it also depicts the relationship between diffraction light and interference light. During the research people find some extraordinary phenomenon, such as null reconstruction and inverse polarizing effect. But there is a disadvantage in this new polarization holography theory, where only under a peculiar circumstance can we get a faithful reconstruction. The circumstance can be expressed as “A+B=0”, where A and B refer to the coefficients for intensity and polarization holograms respectively. In this research, we calculate the formula of diffraction light’s polarization, and extract the A+B factor in it. Then we establish a series of equations which can let the diffraction light faithfully reconstruct, no matter what value of A plus B is. From the result, we can use an artificial reference beam which is corresponding to the signal beam to generate the hologram. Under this condition, the polarization of the diffraction light is similar to the signal. For simplification, we only discuss the signal wave with circular polarization and experimentally verify the result.

Near-field optical disk (NFOD) is a novel and demanded developments of optical storage technology. The nonlinear plasmonic coupling effect of the complete nano recording unit is important for increasing the near and far field optical readout contrast. Here, we present a simple plasmonic near-field coupling optical disk system. The near-field coupling effect between two nano-recording marks with various thickness of the dielectric spacer layer are investigated.

The growing amount of data generated every year creates an urgent need for improved methods and new storage media. Far-field super-resolution techniques have provided the foundation for nanoscale 3D optical data storage towards a petabyte-level capacity on DVD-sized discs. However, a suitable recording medium for high-density information storage over long-term periods and with low energy consumption is still lacking. Rare-earth doped nanocrystals, which feature ladder-like-arranged energy levels enabling emission from ultraviolet to near-infrared, have a fluorescence lifetime two to three orders of magnitude longer than that of other fluorophores and offer the potential for low-power super-resolution data reading. Moreover, the reduction of graphene oxide to reduced graphene oxide induces permanent changes in its chemical and optical properties which can be used for data recording. Here, we demonstrate the reduction of graphene oxide induced by rare-earth doped nanocrystals via FRET towards super-resolution optical data storage with ultra-high capacity, ultra-long lifetime and ultra-low energy consumption. Yb3+/Tm3+-doped core-shell nanoparticles were synthesized via co-precipitation method and their fluorescence spectrum was obtained using a home-built microscope. A solution of rare-earth doped nanocrystals and graphene oxide nanoflakes was spin-coated on coverslip glass and fluorescence lifetime measurements were conducted to confirm efficient FRET. The reduction of graphene oxide was attributed to the transfer of energy quanta from up-converting rare-earth doped nanocrystals under 980-nm laser excitation. High-contrast images of the data bits were generated by super-resolution optical microscopy based on rare-earth doped nanocrystals due to the different degree of fluorescence quenching between graphene oxide and reduced graphene oxide.

Even though optical storage has been well heralded as green techniques, the conventional optical memories have been constantly challenged as they reached theirs physical limits imposed by nonlinear effects. Recently, nanophotonics harnesses light’s interaction with materials at the nanoscale including the generation of nanoscale optical probes and the interaction with nanocomposite materials, offering bottom-up new approaches far superior to the conventional technology. In this regard, nanophotonics has emerged as a major propellant for the next generation of ultra-high capacity optical memories for big data. In this talk, we present the recent development of ultra-high capacity optical memories multiplexing information in the physical domain of the writing beams through tailoring the interaction between a tightly focused pulsed laser beam and plasmonic materials [1]. To circumvent the diffraction limit of light discovered by Ernst Abbe, tremendous research approaches have been developed including stimulated emission depletion (STED) microscopy [2]. Through coherently manipulating the distribution of excitons in the fluorophore molecules by a dual-beam approach, where one Gaussian shaped beam can pump the molecules into the excited state while the second doughnut shaped beam can inhibit the subsequent emission through stimulated emission processes, STED microscopy enables superresolved imaging as well as laser lithography [3, 4]. Based on this principle, superresolution optical memories enabled by the dual-beam approach has been demonstrated with an ultra-high equivalent capacity [5].

We have characterized a new type STED microscope which combines a high numerical aperture (NA) optical head with a solid immersion lens (SIL), and we call it as SIL-STED microscope. The advantage of a SIL-STED microscope is that its high NA of the SIL makes it superior to a general STED microscope in lateral resolution, thus overcoming the optical diffraction limit at the macromolecular level and enabling advanced super-resolution imaging of cell surface or cell membrane structure and function Do. This study presents the first implementation of higher NA illumination in a STED microscope limiting the fluorescence lateral resolution to about 40 nm. The refractive index of the SIL which is made of material KTaO₃ is about 2.23 and 2.20 at a wavelength of 633 nm and 780 nm which are used for excitation and depletion in STED imaging, respectively. Based on the vector diffraction theory, the electric field focused by the SILSTED microscope is numerically calculated so that the numerical results of the point dispersion function of the microscope and the expected resolution could be analyzed. For further investigation, fluorescence imaging of nano size fluorescent beads is fulfilled to show improved performance of the technique.

Metasurfaces, the two-dimensional (2D) sub-wavelength artificial structures, where light is not required to have a deep penetration, have shown the ability to tailor the amplitude, phase and polarization of light. The functionalities of various optical components can be realized by metasurface-based design, such as beam splitters, filters, waveplates, deflector, lens and holograms. Here, we propose a new type of metasurface based on the concept of ultra-thin film interference and experimentally demonstrate its feasibilities in beam deflector, light focusing and broadband meta-hologram in visible spectrum. Considering an ultra-thin thin film interference system, a sandwich structure, composed of air, a lossy material layer and a metallic mirror, the reflection of this system can be regarded as the linear superposition of the partial reflections from first interface and from the cavity after several roundtrips. First, we calculate the phases and reflections of various thicknesses of amorphous silicon (a-Si) on top of aluminum layer under normal illumination of an unpolarized light in the wavelength region from 400 to 850nm. 2 π phase coverage can be achieved by changing the film thickness of a-Si within 50 nanometers. We select two thicknesses (2-level phase modulation) for the demonstration of meta-devices. The ultra-flat grating metasurface for beam steering are designed. The reflection angles of grating metasurface can be modulated by changing its period, while the specular reflection is inhibited. We further demonstrate computer-generated holograms (CGH) based on ultra-thin interference metasurface. The holographic images are reconstructed by the combinations of phase- and amplitude- modulation. These devices show the great potential and CMOS-compatibility in the application of optics, display, security printing, and metasurface-based optical storage system.

Bio chip and bio disc are rapidly growing technologies used in medical, health and other industries. While there are numerous unique designs and features, these products all rely on precise three-dimensional micro-fluidic channels or arrays to move, separate and combine samples under test. These bio chip and bio disc consumables are typically manufactured by molding these parts to a precise three-dimensional pattern on a negative metal stamper, or they can be made in smaller quantities using an appropriate curable resin and a negative mold/stamper. Stampers required for bio chips have been traditionally made using either micro machining or XY stepping lithography. Both of these technologies have their advantages as well as limitations when it comes to creating micro-fluidic patterns. Significant breakthroughs in continuous maskless lithography have enabled accurate and efficient manufacturing of micro-fluidic masters using LBRs (Laser Beam Recorders) and DRIE (Deep Reactive Ion Etching). The important advantages of LBR continuous lithography vs. XY stepping lithography and micro machining are speed and cost. LBR based continuous lithography is >100x faster than XY stepping lithography and more accurate than micro machining. Several innovations were required in order to create multi-depth patterns with sub micron accuracy. By combining proven industrial LBRs with DCA’s G3-VIA pattern generator and DRIE, three-dimensional bio chip masters and stampers are being manufactured efficiently and accurately.

An application of Orthogonal Frequency Division Multiplexing (OFDM) method to optical disc recording/readout is presented. OFDM has been widely used in the field of telecommunication owing to its highly efficient frequency usage. However OFDM has not been applied to optical disc recording because it is a multiple data transfer method and needs to record analog signals. Partial Response Maximum Likelihood (PRML) used in the current optical disc systems requires a certain kind of analog recording. Although optical recording usually creates binary marks, it is possible to obtain arbitrary analog readout signals by using PWM method. Another technique to generate analog signals using the oversampled binary recording is described and applied to multiple level recording. In addition, it is found that the level adjustment of multiple carriers for OFDM leads to the advantage when it is applied to the optical disc system. Using the simple transfer function model of the optical disc system, two types of readout signals using PRML and OFDM are calculated and then their qualities are compared. Since Quadrature Amplitude Modulation (QAM) method can be combined with OFDM, it is possible to increase the recoding density of optical disc systems. A method employing OFDM with 64-QAM and the pre-enhance method to the high frequency carrier shows an ability of 1.5 times recording density of the conventional Bru-ray Disc (BD).

An adaptive optics system is designed and constructed to recover information from damaged optical media. The system is based on an Olympus IX70 microscope with custom illumination and detection. A scanning 408nm laser beam provides both the reference beam for the adaptive optics system and the data beam for imaging of data marks. A two-dimensional galvanometer system is used to scan the focused laser over the sample, and a precision z stage is used to change focus planes. The adaptive optics system is based on a Thorlabs AO kit with a Shack-Hartman wavefront sensor and a deformable mirror. A custom objective lens using a solid immersion lens is implemented that provides NA up to 1.5. Several types of data storage substrates are examined, including partial DVD and BD substrates, small 2cm-square pieces of DVD and BD substrates, and dust fragments on the order of 2mm in size. In order to view the dust fragments, they are collected on a microscope slide and melted to reflow the plastic and reveal data-containing flakes.