This PDF file contains the front matter associated with SPIE Proceedings Volume 7986, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

A single device which can demodulate both DPSK and DQPSK formats by simply rotating a quarter-wave plate is proposed in this paper. Through introducing LC phase retarder and polarization-dependent phase compensation, fast tuning time of 50ms and low PDFS of less than 300MHz are successfully realized.

A modeling method for passive photonic components such as add-drop filters is presented, which allows for fast and accurate system-level ONoC simulation in an electrical EDA simulation environment. This method can be used for design verification of electronic / photonic heterogeneous system, and allows for considerable acceleration of the system simulation.

Chromatic dispersion (CD) and polarization-mode dispersion (PMD) monitoring methods based on radio-frequency (RF) spectrum analysis and optical filtering are demonstrated. By using a narrow band fiber Bragg grating (FBG) notch filter, which is centered at 10GHz away from carrier, 10GHz RF power can be used as a CD-insensitive PMD monitoring signal. By taking the 10GHz RF power ratio of non-filtered and filtered signal, PMD-insensitive CD monitoring can be achieved. If the FBG notch filter is placed at optical carrier, the RF clock power ratio between non-filtered and filtered signal is also a PMD-insensitive CD monitoring parameter, which has larger RF power dynamic range and better measurement resolution. Both simulation and experiment results show that the proposed methods are efficient on measuring CD and PMD values in 38-Gbit/s DQPSK and 57-Gbit/s D8PSK systems.

A PbSe quantum dots (QDs) fiber amplifier has been demonstrated. The PbSe QDs were synthesized via sol-gel self-assembly method. The size of PbSe QDs was controlled to 5.5 nm through control of the reaction time as well as the growth temperature. Transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy were used to characterize the PbSe QDs samples. The fiber amplifier was fabricated by coating the QDs onto a tapered optical fiber coupler. Through evanescent wave, the QDs were excited to realize optical amplification. A 1550 nm semiconductor light emitting diode (SLED) as the signal source and a 980 nm laser diode (LD) source as the pump were injected into the fiber coupler simultaneously.

In this paper, correlated photon pairs at 1.55μm are generated in a silicon wire waveguidewith a length of 1.6 mm. The ratio between coincidence count rate and accidental coincidence count rate under room temperature is 19, showing the property of low Raman noise and strong quantum correlation. Moreover, the experiment shows that photon pair generation isstrongly dependent on pump polarization direction. Using quantum perturbation theory, we analyze the contribution of scalar and vectorspontaneous four-wave mixing processes to the generated photon pairs. Due tohigh nonlinear coefficient and high coupling efficiency, the generation rate in quasi-TE mode is much larger than that in quasi-TM mode.The combination of calculated photon pair generation rates through scalar and vector spontaneous four-wave mixing processes agrees well with the experimental result.

We demonstrate the security improvement using ±π/2-phase-shifted SSFBG encoder in time-spreading OCDMA. Compared with conventional 0/π-phase-shifted SSFBG encoder, ±π/2-phase-shifted SSFBG encoder conceals code pattern well in the encoded waveform. We also theoretically analyze and experimentally investigate the influence of input pulse and the experimental measurement matches the calculated result very well.

We experimentally demonstrate silver nanowire based plasmonic devices at optical communication wavelength 1.55 μm. The plasmon propagation loss in a 300 nm diameter silver nanowire is measured to be 0.3 dB/μm. Two types of plasmonic functional devices based on the coupling between two silver nanowires, nano-couplers and nano-splitters, are realized.

The 2nd-order fractional Talbot effect is employed to multiply the 10-GHz optical pulse-train injection for 2nd-order ration-harmonic-mode-locking of a SOA fiber laser at 40-GHz. With improved modulation-depth by enlarging pulse-extinction-ratio from 0.55 to 2.3, the SOAFL generates 8 ps pulsewidth and 170 fs timing jitter when injectionpulse with 2-GHz peak-to-peak chirp.

An optical S-R latch is demonstrated using two injection locked single-mode (SM) Fabry-Perot laser diode (FP-LD). The S-R latch is based on the bi-stability and injection-locking properties of FP-LD. The latch performs simultaneous inverted and non-inverted outputs in set and reset states. The proposed latch performs very well both in set and reset conditions. The switching times of the latch both for inverted and non-inverted outputs in set and reset conditions were measured by oscilloscope and recorded as about 90 ps. For the latching function, very low powers of set and reset signal were required. Power of set signal was -17 dBm and that of reset signal was -7 dBm.

Rare-earth doped fibers for high power fiber amplifiers normally have a small refractive index difference between the core and inner cladding, but have a larger core diameter than conventional telecom fibers. We take advantage of this feature as well as the difference between the optical and acoustic waveguides and proposed several fiber designs to mitigate Stimulated Brillouin Scattering (SBS) to produce higher output powers. The numerical modeling showed that an increase in SBS threshold by 3-5 dB can be achieved using Ge-codopant while maintaining diffraction limited beam quality. The study also highlights the need to take into account the effects of minor refractive index profile variation in evaluating SBS performance.

A special sampling structure based on the double exposure technology is proposed to achieve dual-wavelength lasing in the distributed feedback (DFB) fiber laser. This structure is composed of two grating pitches in one sampling period, which could be realized by changing the fiber's length in the fabrication. And through employing an equivalent phase shift, only a submicrometer-level precision is required for precise phase control. Then a stable dual-wavelength laser with the spacing of 400pm is obtained in the experiment successfully. The output power is 30.46uW and the SMSR is 46dB under a pumped power of 146mw.

Mode-locked lasers with a dispersive cavity whose wavelengths can be tuned by changing either cavity length or modulation frequency, are promising to generate single- or multi-wavelength and wavelength-tunable optical short pulses. The transient states of wavelength tuning in such lasers, which may introduce significant timing and amplitude jitters, is undesirable for applications that require fast wavelength switching or sweeping. In this paper, we numerically and experimentally study the transient states of wavelength tuning in dispersion-tuned mode-locked lasers. The restriction on the tuning step of cavity length or modulation frequency for wavelength tuning to achieve an acceptable pulse performance is obtained.

An improved simulation model of switchable dual-wavelength laser has been proposed, with which the different stabilization behaviors with dual-wavelength lasers based on inhomogeneous and homogeneous active media have been analyzed. The numerical results shows that only one wavelength lasing can be supported by selecting appropriate lasing parameters, which can well explain the switching behavior of dual-wavelength switchable lasers by controlling some lasing parameters such as the pump power into gain media or the lasing intensity and wavelength of injected signal channel.

An SU-8-based arrayed-waveguide gratings (AWG) device with multimode interference couplers (MMI) is designed and fabricated. The demonstrated MMI-AWG device has 4 channels and the channel spacing is 500GHz. The total insertion loss is about 22 dB, which mainly comes from the coupling loss (16dB) between the input/output waveguide and the fibers. The channel crosstalk between adjacent channels is about -12 dB which is close to the simulation result.

In this paper, we review advances and our works in all-solid photonic bandgap fiber gratings. Especially, we report the fabrication and characterizations of long period fiber gratings and fiber Bragg grating arrays realized by forming longitudinal periodic index modulation in an low-loss all-solid PBGFs with high-index Ge-doped rods surrounded by a low index Be-doped ring lattice in the cladding. High order resonances between fundamental core mode and cladding LP₀₁ supermodes are demonstrated and investigated in long period fiber gratings (LPFGs) inscribed in the all-solid photonic bandgap fiber. The fiber Bragg grating array has unusual transmission characteristics, such as large transmission bandwidth and different transmission spectra when launching light into different Ge-doped rods, which is very different from single fiber Bragg grating. These interesting spectral features are analyzed and interpreted.

We propose a fiber-optic temperature sensing method based on a long period fiber grating induced by a heat-shrinkable tube and a metric screw. Our proposed technique employs the relationship between temperature and LPFG insertion loss, and we estimate the loss change using an OTDR.

In this work, we demonstrate three-dimensional (3D) simulations of a third order silicon-based grating with full-width-half- maximum (FWKM) reflection bandwidth of 4nm. This is more than 2 orders of magnitude improvement over a conventional side-walled grating structure. The relationship of grating performance over the infra-red wavelength range is also presented. In order to make this device active, we included an active element, to be inserted in the silicon layer by way of a pin layout. The device has a low power consumption of 114nW and its intrinsic device modulation speed is predicted to function at 40.5MHz.

Insertion loss caused by diffraction effects may yield low throughput in the Fabry-Perot tunable filter. A bidirectional beam propagation method (BPM) is introduced to describe the relationship between the related parameters such as length of air gap and mirror reflectivity and the insertion loss of fiber Fabry-Perot filter. The numerical simulation results indicate that the method can provide a simple and useful way for the device design.

We propose a new design of 25-GHz flat-top multichannel optical filter. The flat-top of optical filters can improve to 2.288x10^-11dB which is superior to that of 5 orders of previous study. The superior performance of dispersion and channel spacing isolation improve 73.5% and 94%, respectively, which compared with previous study.

The random offset of hole-position or random variation of hole-diameter always occur during the actual manufacture process of asymmetric structure photonic crystal fibers. Birefringence of asymmetric photonic crystal fibers with circular air holes and photonic crystal fibers with elliptical air holes are studied numerically based on the finite element method under the perturbation circumstance. The results indicate that when the intrinsic-birefringence of asymmetric photonic crystal fiber is smaller, the random offset of hole-position has larger influence than the variation of hole-diameter. Birefringence resulted from perturbation is less sensitive to asymmetric structures with large pitch or small air-hole. Moreover, the desired birefringence can be obtained by controlling the relative size of the two air holes or the ellipticity of the elliptical-hole.

Different optical access technologies are studied with respect to their power efficiency. Considered networks provide long-reach optical access. A network model that includes various network and energy related parameters has been developed. The influence of uplink capacity limitation and the amount of broadcast downstream traffic on power efficiency is evaluated within the developed network model. Long-reach passive optical networks provide the best power efficiency.

We investigate the polarization dependent characteristic of an acousto-optic filter in photonic crystal fiber and find polarization dependence is strong. By inserting the filter into a fiber loop mirror, the polarization dependence is eliminated effectively, and the polarization dependent loss is reduced from ~4.0 dB to <0.35 dB.

By using cascaded Wavelength Division Multiplexing and pumping in sectionalization method, ASE and feedback were greatly suppressed. At repetition rate of 50kHz and pulse duration of 20ns, gain of amplified signal was 17.1dB with a high signal to noise ratio of 25dB. The whole system is a good choice for a preamplifier of high-power pulse amplification.

Starting from the theory of one-dimensional photonic crystal, a flat-top polarization interleaver filter composed of cascaded thin-film glass cavities is proposed. A detailed design example with three cascaded thin-film glass cavities is given in the paper. The minimum transmissivity of P polarized light at passband is higher than 99.6% and the maximum transmissivity of S polarized light is about 0.1%. The center-frequencies of the transmissivity of P polarized light accord with the ITU standard. The proposed interleaver filter not only has the characteristics of very simple structure, easy to accomplish, but also has high transmittance for P polarized light and good cut-off characteristic for S polarized light. When rotating the cascaded thin-film glass cavities in the horizontal plane with small angle, the filter has the center-frequency tunability characteristic as well.

Based on digital signal processing theory, a novel method of designing optical notch filter is presented for Michelson interferometer with Gires-Tournois Etalon. The method is not only effective and simple, but also can be used to implement the designing of the optical notch filter which has arbitrary numbers of notch points in one free spectrum range. As a designing example, the optical notch filter with one notch point is given in the paper. The change of output intensity spectrum is also investigated for the reflection coefficient of the mirror and the distance between the mirrors deviating from the ideal value, finally the tuning characteristics of the notch filter is discussed.

A novel highly birefringent photonic crystal fiber (PCF) with hybrid cladding is proposed. In this hybrid structural PCF, some air holes of the cladding are selectively filled with high refractive index material. The increased birefringence mainly results from that the symmetry is destroyed further in the designed PCF. The birefringence is theoretically investigated with variant structural parameters and refractive index of the filled material. The plane wave expansion method (PWE) and full-vector finite-element method (FEM) are respectively employed to investigate the optical properties of the proposed PCF. The numerical results show that the designed PCF can provide high birefringence and be well tuned by the structural parameters and refractive index of the filled material. It can be used as all-fiber polarization controllers and highly sensitive sensors.

In present work the effect of two different source of silicon Tetraethylorthosilicate and Octamethylcyclotetrasiloxane on TiO₂-doped SiO₂ films have been studied. The study reveals that film properties depend on the precursors used for deposition. The deposited films are crystalline with broad peak between 2θ = 20° - 30° corresponding to SiO₂ and two strong peak appearing at 2θ = 38.3° and 2θ = 44.6° due to the (004) anatase phase and (210) rutile phase of TiO₂. It is also clear from the SEM study that the particle size of films deposited using TEOS are smaller than the one deposited by OMCTS.

A kind of polymer tube with (elliptical) ring structure is proposed for Terahertz (THz) guiding. The THz polymer tube has the low-loss property due to the fact that the central air core of the polymer tubes traps a large part of the mode power. Properties such as the effective index and the relative absorption loss of the THz polymer tube are investigated. The elliptical polymer tube with a cross-section of elliptical ring structure can be used as a highly birefringent low-loss THz waveguide with a high birefringence (up to the order of 0.01). The birefringence property of the elliptical polymer tubes with different parameters is also calculated and discussed.

The way to improve the reflectivity of chemical composition grating (CCG) sensors is studied. Experimental results show that improving the initial fiber Bragg grating (FBG) reflectivity strength and enhancing the hydrogen concentration in the initial FBG inscription help to increase the reflectivity of the CCG sensors at high temperatures.

An all-fiber ytterbium-doped laser based on nonlinear polarization rotation (NPR) without dispersion compensation and additional filter has been demonstrated. The formation of the dissipative soliton pulse is a self-consistent result of various effects in the laser cavity. Stable mode-locked pulses with pulse energy of 1.1 nJ have been achieved.

We propose and experimentally demonstrate a novel all-optical microwave filter with high quality factor (Q). It is based on a recirculating delay line (RDL) loop in which a semiconductor optical amplifier (SOA) is followed by a tunable narrow-band optical filter and a 1x2 10:90 optical coupler. Converted signal used as a negative tap is generated through wavelength conversion employing the cross-gain modulation (XGM) of the amplified spontaneous emission (ASE) spectrum of the SOA. The converted signal can circulate in the RDL loop so that the proposed filter realizes a high Q factor response after photo-detection. The 1x2 10:90 coupler is employed to extract 10% optical power from the loop as output. A frequency response with a high Q factor of 543, a rejection ratio of 40 dB is experimentally demonstrated.

A Long-Period Fiber Grating (LPFG) fabricated by CO₂ laser in a symmetrical two-hole single-mode fiber (STHSMF) for refraction index (RI) measurement is demonstrated. The solved sugar liquid of different concentration was filled into the holes by capillary force and its RI was experimentally measured. The results show that resonant peak shifts toward shorter wavelengths with its resonance peak intensity changes a little when the external refractive index increases. RI sensitivity of 141.67 nm/RIU have been achieved with R² of 0.975.The temperature sensitivity of the STHSMF is also investigated.

We report the fabrication of extremely short linear-cavity distributed Bragg reflector fiber lasers (DBR-FLs). It has a total length of 7 mm, with the nominal cavity of only 0.4 mm. The FL has a linewidth and polarization beat frequency of 220 Hz and 18.9 MHz, respectively. The relaxation oscillation frequency and its relative peak are 120 kHz and -75dB/Hz, respectively. The FL exhibited low-noise characteristics, with an intensity noise of -107 dB/Hz at 1 MHz. We constructed a FL sensor array that has great potentials for large-scale, high sensitivity sensing applications.

Based on digital signal processing theory, a simple method of designing interleavers is proposed for MZI with fiber ring coupled structure. The results of different coupled structures, including no-ring, single ring coupled on one arm of MZI, single ring coupled on each arm of MZI, two rings coupled on one arm of MZI while one ring coupled on another arm and two rings coupled on the both arms of MZI structures are given and analyzed. The proposed method is not only simple but also effective. At last, take two vertically cascaded rings coupled on one arm and one ring coupled on another arm for instance, the change of spectral transmittance is investigated for each design parameters deviating from ideal value and the tuning characteristics are discussed as well.

An acrylic-based 1x2 Y-Branch POF coupler consists of input POF waveguide, a middle high index contrast waveguide taper and output POF waveguides has been developed. The optical device is based on a 1x2 Y-branch coupler design with a middle high index contrast waveguide taper. Device modeling has been performed using non-sequential ray tracing with an insertion loss of 4.68 dB and coupling ratio of 50:50. Low cost acrylic material has been used for the device substrate. This middle waveguide taper region is constructed on the acrylic block itself without using any additional optical waveguiding medium injected into the engraved taper region. Fabrication of the devices is done by producing the device structures on an acrylic block using high speed CNC machining tool. Input and output POF fibers are inserted in to this device structure in such a way that they are passively aligned to the middle waveguide taper structure. The measured insertion loss is 7.5 dB and with a splitting ratio of 50:50.

Stress-induced birefringence in silica-on-silicon waveguides is analyzed by the finite element method using the normalized plane strain model. The simulation results show that the thermal expansion coefficient of the upper-cladding is the most critical factor. A waveguide with zero birefringence is obtained and used to realize polarization independent AWGs.

We propose a novel mechanical splicer that employs stripping-free fiber connection, which achieves a low connection loss and a short assembly time. We also demonstrate single mode fiber connection with an average loss of 0.2 dB.

Polarization mode dispersion (PMD) is one of the major obstacles in high-speed (above 100 Gbits rate) and long-haul optical communication system. In order to meet the requirements of high-sped optical communication quality, some PMD compensation and mitigation schemes had been developed. Forward error correction (FEC) is useful to increasing the system margin. The combination of distributed fast polarization scrambler (D-FPS) and FEC is an effective method to improving the optical system's PMD tolerance. The fundamental reason is that D-FPS can accelerate the redistribution of the link PMD to enable FEC to be more effective during the periods that would otherwise have PMD outages. Another advantage of this scheme is that it can mitigate the influence of PMD in multichannel system without feedback control and compensation based on each channel. The principle and performance of scrambling is introduced in this paper and the fundamental idea of improving PMD mitigation by using D-FPS combined with FEC is proposed. Some key factors such as scrambling speed and the number of scrambler which affecting the performance of this scheme are also introduced. Finally, proposing an assumption that the impact for system performance caused by the style of FPSs is distributed along the fiber link, and the mathematical estimation model is established. The combination of D-FPS and FEC would be a promising approach for performance improvement in ultra-high-speed optical communication system.

We have demonstrated experimentally simultaneous generation of wavelength-switchable picosecond laser pulses by using a self-seeding configuration that consists of a gain-switched Fabry-Perot laser diode (FP-LD) with an external cavity formed by a tilted multimode fiber Bragg grating (MMFBG). Wavelength-switchable picosecond pulses are obtained and can be switched in a flexible manner by changing the temperature of FP-LD and the modal distribution in the grating. The generation and wavelength switching of short pulses are demonstrated experimentally at 9 discrete wavelengths. The laser pulses have a side mode suppression ratio better than 25dB and a pulsewidth of ~42ps. In particular, we could also obtain dual- and triple-wavelength laser pulses by adjusting the polarization controller carefully in the experiment. This simple laser offers considerable flexibility for various applications such as fiber laser sensors.

We propose a fiber-Bragg-grating Fabry-Perot (FBG-FP) cavity sensor interrogated by a pulsed laser. The FBG-FP cavity is directly written into the same photosensitive fiber, which consists of a pair of FBGs with identical center wavelength. The modulated laser pulses are launched into the FBG-FP cavity. Each pulse produces a group of reflection and transmission pulses. The cavity loss in the FBG-FP cavity is determined from the power ratio of the first two pulses reflected from the cavity, which could be detected for the sensor measurement. This technique has the advantages that it does not require high reflectivity FBG and is immune to the power fluctuation of the light source.

We studied experimentally the bending sensitivity of long-period fiber gratings (LPFGs) written in the single-mode fiber under external tension by CO₂ laser. It is found that the LPFG was not only more sensitive to the fiber bending, but also sensitive to the bending direction, which can be attributed to the asymmetric index modification induced across the fiber section by the CO₂ laser. Thanks to their unique bending characteristics, this kind of LPFGs could find applications in directional fiber bending sensors.

We present two configurations of novel dual coupled microring resonators with different coupling points between dual coupled microring resonators. Analytical expressions of transmission spectra and delays of the two configurations of dual microring resonators are developed using the transfer matrix method. Then the effects of loss and different coupling points on transmission spectra and normalized delays of novel dual coupled microring resonators are investigated. Under the case of considering loss effects, different transmission spectra and delays are found out for the two configurations. Both the transmission spectra and delays of the two configurations have different characteristics as the loss changes. As the loss increases, amplitude of the transmission spectra decreases at different rates. Multiple transmission spectra peaks and delay peaks exist, which can degenerate into a single peak under certain loss condition. Besides, the resonance frequencies of transmission spectra and delays are analyzed as the loss changes. As the loss changes, corresponding resonance frequencies of transmission spectra peaks are partially coincident with the resonance frequencies of delay peaks on both sides of the center frequency, while the delay at the center frequency has significant changes.

We discussed how to design the typical trip-clad high-order mode fiber (HOMF) profiles to achieve the required dispersion properties based on LP₀₂ mode, to compensate all modern transmission fibers, without sacrificing other important properties, such as effective area. Finally, HOMF compensating 100km eLEAF fiber has been designed. Its dispersion at 1550nm is -1217ps/nm/km, and the relative dispersion slope (RDS) is 0.02nm^-1. Only ~345m of HOMF is needed to achieve full dispersion and dispersion slope compensation of the span, while maintaining effective area above 52μm² over the entire C-band.

Influence of splicing the highly birefringent photonic crystal fiber (HB-PCF) with single mode fiber (SMF) under two different experimental conditions is studied in details. The result shows the birefringence of the HB-PCF can be either increased or decreased significantly, depending on the connection conditions of the HB-PCF end, which are classified as case I (the end is closely butted by another fiber) and case II (the end is in open air). From the experiment and theoretical analysis, it has shown that in case I the retardation change of the spliced section of HB-PCF with 0.2mm in length can be 3.2 times larger than the original value. However, in case II the retardation may be reduced to 72.12% of the original one. The obtained result is important for the design and fabrication of optical fiber devices and sensors based on HB-PCFs.

In this paper, we investigate propagation of squeezed light in array of coupled waveguides which has tremendous potential for applications in engineering. We take a look at the possibility of Talbot effect with squeezed states of light. We also demonstrate how Hong-Ou-Mandel effect may be engineered to be relatively immune to fabrication imperfections.