Novel Magnetic Photonic Crystal Structures for Magnetic Field Sensors and Visualizers

Optimized one-dimensional (1-D) magnetophotonic crystals greatly increase the sensitivity of magnetooptical sensors, which are widely used in magnetooptical imaging to observe the magnetic domain patterns in magnetic materials, to observe the vortex states in superconductors, to detect small bits in magnetooptical recording media, to visualize defects in ferromagnetic objects, and to measure the value and spatial distribution of stray magnetic fields. This paper examines the properties of such devices operating in the optimized reflection (doubled Faraday rotation) mode and discusses the use of 1-D magnetophotonic crystals as sensors.     

Optimization of fiber amplifier SCM lightwave video systems usingdirect and external modulation

An analysis of the design factors involved in optimizing laser transmitters for SCM video distribution networks is presented. This includes optimization of the erbium-doped amplifier, linearized external modulation, and laser overmodulation to increase the optical loss budget. A full nonlinear distortion spectral analysis is employed to determine the dependence of the optimum optical modulation index on the allowable postamplifier loss. A general optimization procedure has been developed for the fiber amplifier and modulator to maximize the postamplifier loss for a specified CNR objective. Results are presented showing a comparison between the distribution capacity of direct and externally modulated SCM-EDFA systems for VSB-AM and FM-SCM transmission systems     

Bimetallic non-alloyed NPs for improving the broadband optical absorption of thin amorphous silicon substrates

We propose the use of bimetallic non-alloyed nanoparticles (BNNPs) to improve the broadband optical absorption of thin amorphous silicon substrates. Isolated bimetallic NPs with uniform size distribution on glass and silicon are obtained by depositing a 10-nm Au film and annealing it at 600°C; this is followed by an 8-nm Ag film annealed at 400°C. We experimentally demonstrate that the deposition of gold (Au)-silver (Ag) bimetallic non-alloyed NPs (BNNPs) on a thin amorphous silicon (a-Si) film increases the film''s average absorption and forward scattering over a broad spectrum, thus significantly reducing its total reflection performance. Experimental results show that Au-Ag BNNPs fabricated on a glass substrate exhibit resonant peaks at 437 and 540 nm and a 14-fold increase in average forward scattering over the wavelength range of 300 to 1,100 nm in comparison with bare glass. When deposited on a 100-nm-thin a-Si film, Au-Ag BNNPs increase the average absorption and forward scattering by 19.6% and 95.9% compared to those values for Au NPs on thin a-Si and plain a-Si without MNPs, respectively, over the 300- to 1,100-nm range.     

Magneto-optical methods for analysis of nanothick magnetodielectric films

An original design of a compensation magnetic system is suggested and implemented: it enables one to measure the difference signal by placing in the measuring device a film on a paramagnetic device and the original paramagnetic substrate, thereby providing the full compensation of the paramagnetic substrate.     

Tuned optical receivers for microwave subcarrier multiplexedlightwave systems

An analysis of tuned optical-receiver noise performance for microwave subcarrier multiplexed lightwave systems is presented. The effect of correlation between the gate and the drain HEMT noise sources and the design of tuning networks to obtain partial noise cancellation were investigated. Anoptimization algorithm is used to determine the tuning elements values for minimizing noise of 16 dB for a 60-video-channel subcarrier multiplexing (SCM) system, and 12 dB for a 120-channel system, which allows a significant increase in passive optical network distribution capacity. Design results for tuned front-end receivers encompassing the effects of p-i-n, HEMT, and SCM band parameters are presented     

Demonstration of tunable optical notch filter using 1-D opto-VLSI processor

An opto-very-large-scale-integrated (opto-VLSI)-based tunable optical filter structure is demonstrated. Filter tunability is achieved by reconfiguring the holographic diffraction grating of an opto-VLSI processor, allowing virtually any type of filter response to be synthesized. A proof-of-concept tunable notch filter with wavelength span of 7 nm is experimentally verified.     

Chaining geographic information Web services

Client-coordinated, static, or mediated chaining of GIS Web services enables easier on-demand access to customized geographic information.     

Ultimate limits of subcarrier multiplexed lightwave transmission

An analysis of the fundamental limits in SCM lightwave transmission is presented. The system studied comprises an ideal overmodulated laser transmitter with nonsymmetrical threshold clipping and a shot-noise limited receiver. The power spectral density of the nonlinear distortion noise is evaluated and the optimum modulation index m/sub opt/ is determined. Results are given for the ultimate requirements for VSB-AM and FM SCM modulation formats.<>     

基于DMD滤波器的波长间隔可调谐的双波长单纵模光纤环形激光器

提出一种稳定的波长间隔可调谐的双波长单纵模环形光纤激光器。在复合环形谐振腔中,采用由数字微镜装置（DMD）滤波器和两个不同长度的次级环形谐振腔组成的多重滤波的方式来选择激光器的工作模式。其中,DMD滤波器可以从掺铒光纤的自发增益谱中任意选择两个波长并将它们耦合进光路中;次级环形谐振腔作为模式滤波器,可以保证激光器输出单纵模激射;利用非线性光子晶体光纤（HN-PCF）的四波混频（FWM）效应,使激光器输出均衡平稳的双波长激射。在室温条件下,不用移动实验装置中的任何器件,通过将位置不同的光栅映射在DMD滤波器上来实现双波长间隔可调谐,调谐范围为0.165nm到1.08nm,调谐步长为0.055nm。     

Magnetic photonic crystals: 1-D optimization and applications for the integrated optics devices

The optimization of multilayer one-dimensional (1-D) magnetophotonic crystals (MPCs) with multiple phase shifts, enabling their design to be tailored to practical photonics applications, is reported. The properties of sample optimized structures suitable for application in infrared intensity modulators are discussed. A novel scheme of high-resolution magnetic field sensing using MPCs is proposed. The effect of material absorption on spectral properties is shown.