标量衍射理论模拟蚀刻衍射光栅

讨论用于光通信的集成波分复用/解复用器件蚀刻衍射光栅（EDG）,它是波分复用光通信的核心器件的一种。EDG基于平面波导的Rowland圆结构,光栅面是平面。光栅的每一个齿面都垂直于齿面中心和输入波导端点的连线。基于标量散射场满足的Hemholtz方程,推导出Rowland圆上场分布的精确表达式。利用这个模型对设计好的器件参数进行了模块形状、谱响应、色散等复用性能的模拟,并对插入损耗和串扰进行了简要分析。     

基于分束器与双向型的光分插复用器分析研究

在分析了光纤光栅光分插复用器结构的基础上,设计了双向型和基于分束器与双向型2种新型的四波长光分插复用器结构。双向型光分插复用器结构与传统的光分插复用器相比可以处理双向网络信号,其特点是系统中相对较少地使用环形器,减少了系统损耗,输出光谱与原光谱更接近;基于分束器与双向型的光分插复用器与双向型相比增加了传输的路数。采用OptiSystem软件对两种结构进行仿真,仿真实验结果显示,双向型和基于分束器与双向型光分插复用器能很好地完成四波长同时上下载任务。     

聚合物光波导端面磁流变抛光工艺(英文)

光波导端面的表面质量会严重影响光波导器件的光耦合封装性能,耦合封装前必须对波导器件端面进行抛光处理.目前聚合物光波导端面主要依靠传统研磨盘进行抛光处理,该工艺工序复杂、抛光效率低已成为制约聚合物波导器件应用的瓶颈.基于聚合物光波导材料优良的加工特性,通过对比实验提出了聚合物光波导的磁流变端面抛光工艺.采用5μm、0.5μm和1μm粒径的氧化铈抛光粉分别配制研磨盘抛光液及磁流变抛光液对3 mm×3 mm聚合物光波导端面进行抛光实验,发现磁流变加工对聚合物光波导端面进行一次2 m in光栅扫描抛光就具有比传统研磨盘约3 h精、粗抛光较好的端面质量.经过白光干涉仪测量,磁流变抛光后光波导端面表面粗糙度的均方根值达到了2.6 nm,传统端面抛光端面粗糙度均方根值为128.7 nm.通过自动对准耦合平台测试,结果显示通过磁流变端面抛光的光波导的插入损耗由抛光前的32.7 dB降低到了17.8 dB.磁流变抛光方法可以对聚合物光波导端面进行快速、高性能的抛光,在光波导应用领域具有非常广阔的应用前景.     

SAC-OCDMA系统中AWG的应用及串扰分析

概述了阵列波导光栅的特点及其在谱域幅度编码的光码分多址通信系统中的应用。基于地址码M序列,采用数值计算的方法,分析了阵列波导光栅的串扰对谱域幅度编码的光码分多址通信系统误码率性能的影响。结果表明,当阵列波导光栅的串扰较小时(Rc=-27dB),谱域幅度编码的光码分多址通信系统具有较好的性能;而当其串扰较大时(Rc=-20dB),谱域幅度编码的光码分多址系统的性能明显恶化,成为影响谱域幅度编码光码分多址通信系统性能的一个重要因素。     

光纤光栅应用于梳状滤波器和光分插复用器(OADM)的研究

研究了光纤光栅在梳状滤波器和光分插复用器(OADM)中的应用特性。基于传输矩阵法对Sinc取样光栅反射谱进行分析,分析了取样光栅长度、折射率调制深度和取样周期等光栅参数对Sinc取样光栅反射谱的影响规律。根据各参数对Sinc取样光栅反射谱的影响规律构造了4种反射率高、反射峰间隔均匀及谱宽稳定的Sinc取样光栅梳状滤波器,为梳状滤波器的设计与制作提供了新思路、新技术。用OptiSystem软件对光纤Bragg光栅型光分插复用器进行了仿真研究。研究表明,经过光纤光栅光分插复用器后,下载和除了下载的光谱峰值基本为-4dBm,下载的功率也基本是均衡的。     

扩束光纤与宽波导光栅的光耦合特性

为了研究光纤与宽波导光栅的有效耦合,基于高斯光束与波导光栅的光耦合理论,以30μm宽波导光栅为研究对象,利用矩阵光学和高斯光束理论分析和设计了一种扩束光纤,并通过分析其耦合损耗,建立了扩束光纤与波导光栅耦合模型.优化所设计扩束光纤的结构参数后,得到束腰半径为10.8μm的输出光束.最后分析了扩束光纤的结构容差,并讨论了所设计扩束光纤的输出光束、单模光纤的输出光束以及束腰半径为16 μm的自由空间高斯光束各自在光栅表面的位置变化对光栅耦合效率的影响.可知扩束光纤输出的光束与单模光纤输出的光束相比具有较大的位置容差,与束腰半径为16 μm的自由空间高斯光束相比,光耦合效率基本相同.     

在阵列波导光栅(AWG)波分复用器件中用重叠积分方法和BPM方法模拟计算波导耦合系数的比较研究

在阵列波导光栅(AWG)波分复用器件中用重叠积分方法和BPM方法模拟计算波导耦合系数的比较研究     

一种实现空间光-单模光纤的自动耦合方法

精确定位耦合光斑在光纤端面上的位置是空间光与单模光纤耦合技术的关键.提出由压电陶瓷、控制器、驱动器、光电探测器、耦合透镜及反射镜组成闭环控制系统,使用光栅式扫描初步确定最佳耦合位置后再用五点跟踪法结合一维平动精确定位实现自动耦合.推导出扫描所需步长和时间,详细阐述了光栅式扫描和五点跟踪法原理.实验结果表明,该方法可以在较短时间内根据耦合入光纤的光功率大小自动搜寻到最佳位置,获得59.2%的最大耦合效率,能校正由地表震动、气流扰动等低频干扰造成的数值偏差保持较高的耦合效率.     

SOI光电子集成

SOI（Silicon-on-Insulator)光电子集成已成为十分引人注目的研究课题，其工艺与CMOS工艺完全兼容，可以实现低成本的SOI基整片集成光电子回路。本文综述了近几年来SOI集成光电子器件的发展以及一些最新的研究进展，着重分析几种最新型光无源器件的工作原理和结构，包括SOI光波导、SOI光波导耦合器、SOI光波导开关、相位阵列波导光栅（PAWG）、基于SOI的光探测器等，并介绍了中国科学院半导体所集成光电子国家重点实验室的研究进展。     

一种用于通信C波段的光轨节点无源集成芯片

光轨是一种新型光通信网络结构,具有交换粒度小、带宽利用率高等优点。本文提出一种应用于通信C波段的新型光轨节点无源集成芯片,支撑1 545 nm、1 550 nm和1 555 nm三个C波段波长的通信。该新型光轨节点无源集成芯片是一种基于SOI纳米波导材料的片上微器件系统,核心器件由基于微环谐振器的解复用器和基于马赫-泽德尔干涉仪的环加强型热光光开关构成。通过理论计算和软件仿真,分别分析了解复用器和光开关的光学和通信性能,结果显示微环解复用器3个波长信道的串扰分别为22.5 dB、16.9 dB和16.3 dB;光开关的消光比分别为16.6 dB、19.7 dB和21.5 dB;插入损耗分别为0.86 dB、0.85 dB和0.68 dB,功耗约为51 mW。     

Analysis of multimode effects in the free-propagation region of a silicon-on-insulator-based arrayed-waveguide grating demultiplexer

Multimode effects in the free-propagation regions (FPRs) of an arrayed-waveguide grating (AWG) demultiplexer based on silicon-on-insulator are considered. Some undesired multimode effects, such as the increase of the insertion loss and the cross talk, are studied by use of a method of three-dimensional guided-mode propagation analysis. It is found that the multimode effects for the edge channels are more serious than those for the central channel. For an AWG demultiplexer with a small channel number, the multimode effects can be minimized by choosing appropriate FPR parameters such as the length and the thickness of the FPR. The coupling coefficient between the FPR and an arrayed waveguide is sensitive to the thickness of the FPR.     

Effect of light source spectral modulation on wavelength interrogation in fiber Bragg grating sensors and its reduction

In the fiber Bragg grating sensing using a superluminescent diode as the light source and an arrayed waveguide grating as the wavelength interrogator, the wavelength measurement error due to the spectral modulation of the superluminescent diode is theoretically formulated and quantitatively analyzed by computer simulation. It is shown that the wavelength measurement errors produced with the use of real superluminescent diodes are in very good agreement with the theoretical results. In order to reduce the wavelength measurement error due to the spectral modulation of superluminescent diode, two different types of remedies are proposed that utilize the temperature switching of superluminescent diode and that adjust the bandwidths of fiber Bragg grating and arrayed waveguide grating, and their efficacies are experimentally demonstrated together with good quantitative agreement with the theoretical calculation.     

Optical demultiplexer using a silicon concave diffraction grating

A demultiplexer composed of a concave diffraction grating and a multimode slab waveguide is attractive since it has many advantageous features. However, this type of demultiplexer has had high demultiplexing losses until now, because the concave diffraction gratings used had poor diffraction efficiency. A silicon concave diffraction grating has been developed to overcome this problem, manufactured by cylindrically bending a thin silicon plane diffraction grating. The diffraction efficiency of this grating was 82% at a blaze wavelength. The five-channel demultiplexer was assembled with this grating as well as with a multimode slab waveguide and a fiber array. Its branching loss was in the 1.4-1.8-dB range.     

Aberration properties in a chirped grating for coarse wavelength division demultiplexing

We studied the imaging performance of a chirped grating for a demultiplexer designed for coarse wavelength division multiplexing using a wavefront aberration analysis and the ray tracing simulation. The demultiplexer was composed of a chirped grating, cylindrical lenses, and a waveguide. The best image point and the spot shape focused by the chirped grating were effectively calculated with the wavefront aberration. We applied the aberration analysis to design a waveguide to connect branched beams to photodetectors, and we confirmed the demultiplexing performance experimentally.     

Effects of apodization on a holographic demultiplexer based on a photopolymer grating

An investigation of the effects of apodization on a holographic demultiplexer that is based on a photopolymer grating is presented. Uniform and Gaussian apodized gratings are fabricated in a DuPont HRF-150-38 photopolymer. From the theoretical and experimental results, the spectral response of the apodized grating has a larger main lobe but lower sidelobes than those in the uniform-grating case. A 42-channel demultiplexer that is based on the Gaussian apodized grating with an 0.4-nm channel spacing is demonstrated. A cross-talk level of -30 dB and an interchannel uniformity of 1.5 dB are archived in the wavelength range of approximately 1550 nm.     

Sidelobe suppression design of etched diffraction grating demultiplexers using optimized air trenches in front of each output waveguide

An etched diffraction grating (EDG) demultiplexer with high sidelobe suppression is designed. Sidelobes resulting from two adjacent wavelengths are suppressed by etching two optimized rectangular air trenches in front of each output waveguide that can induce large resonance loss in the adjacent wavelength but have little influence on the operational wavelength. The designed EDG demultiplexer can suppress crosstalk to less than 50 dB in theory.     

Design considerations for narrow-band dielectric resonant grating reflection filters of finite length

An interference-waveguide approach is developed to predict the response of a resonant grating reflection filter and to provide a better understanding of the resonant process. An expression for the reflected field that accounts for all internal boundary reflections within the filter is developed. Under the assumption of an anti-reflective design, expressions characterizing the line shape of a filter of infinite length are first developed; then the effects of finite length on the response are determined. Expressions relating the length of the filter to the peak reflection efficiency and line width are developed. The degradation of the response as a function of filter length is evaluated. An equivalent waveguide representation is used to determine the location of the resonance as well as the spectral and angular linewidths of the filter. The minimum obtainable spectral linewidth for a filter of given length is determined to be on the order of deltalambda approximately lambda2/L. Rigorous analysis is used to verify the interference-waveguide approach.     

Cost-effective and high-resolution wavelength interrogation unit using an incomplete asymmetric arrayed waveguide grating

This paper presents a wavelength interrogation unit using an incomplete asymmetric arrayed waveguide grating (AWG) without output waveguides. The incomplete asymmetric AWG converts the wavelengths of the incident light into a spatial intensity distribution. The center of the spatial distribution is determined by a one-dimensional position sensitive detector (PSD). The simulation results show that wavelength shifts can be precisely interrogated by the device with a wavelength resolution of 3.5 pm. The device can be applied to the interrogation of fiber Bragg grating (FBG) temperature sensors with the temperature resolution of 0.3°C.     

Analysis of antiresonant reflecting optical waveguide gratings by use of the method of lines

The modal spectral response of an antiresonant reflecting optical waveguide (ARROW) with periodic corrugations or grating is calculated for both shallow and deep gratings with the Method of Lines. The effect of the ARROW layer thickness and the grating depth on the spectral response is studied. It is found that when the ARROW-layer thickness is close to resonance, the ripples in the reflection spectra become smooth and the peak reflectivity drops. This is attributed to the large increase in the leakage loss of the ARROW waveguide near resonance. The ARROW grating is characterized by modal reflectivity spectra, which exhibit a strong polarization discrimination property, in favor of the TE polarization.