A New 1×K Tunable Multi-wavelength Router and its Features

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｗａｖｅｌｅｎｇｔｈｒｏｕｔｅｒｓ (ＷＲｓ)ａｒｅｋｅｙｄｅｖｉｃｅｓｉｎｗａｖｅｌｅｎｇｔｈ ｒｏｕｔｉｎｇａｌｌ ｏｐｔｉｃａｌｎｅｔｗｏｒｋｓ.Ｒｅｃｅｎｔｌｙ ,ｒｅｓｅａｒｃｈｆｏｒｔｈｅＷＲｓｈａｓｂｅｅｎｏｎｅｏｆｈｏｔｓｐｏｔｓｉｎｗａｖｅｌｅｎｇｔｈｄｉｖｉｓｉｏｎｍｕｌｔｉｐｌｅｘｉｎｇ (ＷＤＭ )ｎｅｔｗｏｒｋｔｅｃｈｎｏｌｏｇｉｅｓ[1,2 ] .Ｂｙｄｉｆｆｅｒｅｎｔｒｏｕｔｉｎｇｐａｔｔｅｒｎｓ,ｔｈｅＷＲｓｃａｎｂｅｄｉｖｉｄｅｄｉｎｔｏｔｗｏｋｉｎｄ…     

A New 1×K Tunable Multi-wavelength Router and its Features

Tunable wavelength routers (TWRs) for multiple wavelength selection are key devices in dynamic wavelength-routing wavelength division multiplexing (WDM) networks. In this paper, by cascading conventional 2×2 TWRs, a new 1×K TWR is proposed for large-scale dynamic wavelength-routing WDM networks. When the cascading numbers are smaller, the 1×K TWR can be directly applied to networking WDM networks. When the cascading numbers are larger, the 1×K TWR can be carried out by the integrating method and be extensively used to networking various multi-wavelength optical networks by the way of “EDFA+TWR”. Though the cascading method proposed is based on the acousto-optic TWRs, it can be also applied to cascading other kinds of TWRs.     

一种新型微机电系统可调光衰减器

一种新型的低成本、小体积的电磁驱动微机电系统可调光衰减器,可用于密集波分复用系统中各信道的动态增益平衡。该器件采用电磁线圈驱动绕100微轴转动的微反射镜,运动部件行程极小。驱动电压为0～8V,工作范围0～35dB,动态响应时间小于2ms,插入损耗小于0．8dB,回波损耗小于-50．5dB。器件采用微细电火花加工技术制作,加工精度为微米量级。技术成熟,工艺简单,易于批量生产。采用有限元分析软件ANSYS对器件的结构建模,对电磁场及衰减曲线进行了理论分析,并与实测数据进行了比较,得出了相当满意的结果。     

基于液晶可调滤光片的广角多光谱成像光学系统设计

基于液晶可调滤光片(Liquid Crystal Tunable Filter,LCTF)的分光原理,设计一种工作谱段为400~720nm,焦距4.5mm,视场角140°,F数为1.28的广角多光谱成像光学系统。该光学系统由前端光学镜头、LCTF和成像镜头组成,其中前端光学系统镜头将入射光束进行扩束,同时将入射光束的广角视场缩小至LCTF可接收角度范围内;LCTF利用液晶材料的电控双折射效应,实现对某一波长光信号的选择透过。根据多光谱成像系统的总体方案,对光学系统的各光学参数进行合理选取。设计结果表明,整个系统在120lp/mm的空间频率处轴上及轴外的调制传递函数MTF均大于0.4。     

波分复用薄膜带通滤光片的中心波长温度稳定性

讨论了影响波分复用薄膜滤光片中心波长漂移的因素 ,着重分析了滤光片的温度稳定性。根据实验结果 ,借助于高桥模型 ,分析计算了滤光片的折射率温度系数、线膨胀系数和泊松比以及它们对温度漂移的影响。得到了Ta2 O5/SiO2 滤光片薄膜的折射率温度系数、线膨胀系数、泊松比分别为 1× 10 -5℃-1,5× 10 -7℃-1和 0 12 ,指出了这三个参量是影响温度稳定性最重要的因素 ,特别是薄膜的折射率温度系数。对特定的基板热膨胀系数 ,通过调节滤光片的干涉级次和间隔层材料 ,可望得到零温度漂移的稳定滤光片。     

Design of Two 8-Channel Optical Demultiplexers Using 2D Photonic Crystal Homogeneous Ring Resonators

ABSTRACT

Ring resonators have always been referred to as a highly flexible structure for designing optical devices. In this paper, we have designed and evaluated two 8-channel optical demultiplexers using photonic crystal ring resonators. The purpose of this study is to investigate the flexibility of this type of resonator for designing and manufacturing optical devices based on photonic crystals. To the extent that we have investigated the literature, there is no report so far on such a study. For this purpose, two structures with the same structural parameters, but only with a difference in the type of lattice constant (square or triangular) are used. Both structures have a common photonic band gap within a proper range for telecommunication applications used in wavelength-division multiplexing (WDM) systems. Both designed structures have an average crosstalk of ?26 dB. For the demultiplexer structure with a square lattice constant, the quality factor and the transmission coefficient are 3,046 and 93.7% respectively, and its channel spacing is 1.97 nm. For the structure with a triangular lattice constant, the quality factor and the transmission coefficient are 1577.7 and 94.5%, respectively and its channel spacing is equal to 4 nm. To obtain the photonic band gap of the structures, the plane wave expansion (PWE) method is used and the output spectrum of the structures is obtained using the finite-difference time-domain (FDTD) method. The good results obtained in this study is through designing and simulating optical demultiplexer structures only by creating a change in the type of lattice constant used. This undoubtedly justifies the high flexibility of ring resonators, when used in the design of optical devices, as well as their suitability for the use in WDM systems     

一种用于密集波分复用系统中的可调谐液晶法布里-珀罗滤光片

基于液晶分子的双折射特性，设计并制作了一种结构简单的可用于波分复用系统中的可调谐液晶法布里-珀罗滤光片。对器件的光谱调谐特性进行了分析和模拟，并得到了液晶分子的折射率调制与其分子在电场作用下产生的转动角度之间的关系式。最后，对所设计的结构进行了制作和实验，测试结果显示了滤光片的性能受液晶分子的排列特性和法布里-珀罗腔的反射镜参量的影响较大，同时实验表明了这种利用向列型液晶分子作为法布里-珀罗腔内介质的可调谐滤光片在加电压调试下其调谐性能良好，调谐范围可覆盖C波段，透过峰的半峰全宽达到了0．8nm，实验结果与设计相吻合。     

基于硅基液晶显示技术的可见光光学目标模拟器的研制

为了产生制导武器仿真系统中所需的逼真的目标背景图像,建立了基于硅基液晶显示技术的可见光光学目标模拟器。给出了模拟器图像输出的实际效果图以及光学参量的测试方法和数据。测试表明,该装置有较好的亮度、对比度和均匀性,与传统的阴极射线管显示技术相比有效减轻了图像闪烁问题,能够提供稳定的视频输出,更有利于仿真系统中对动态目标的识别,是一种较为理想的图像模拟装置。同时给出了双复眼光学系统初始结构的计算方法并推导出简单的计算公式,该算法可以应用于其他双复眼照明系统中。     

Reconfigurable optical multiplexer based on liquid crystals for polymer optical fiber networks

In this work, different novel 3×1 multiplexer structures for being used in polymer optical fiber networks are proposed. Designs are compact, scalable, and of low consumption, capable of operating in a large wavelength range simultaneously 660, 850, and 1300 nm, due to the use of nematic liquid crystal cells. Light that comes from each input port is handled independently and eight operation modes are possible. Control electronics has been made using a programmable integrated circuit. Electronic system makes available the managing of the optical stage using a computer. An additional four optical sensors have been included for allowing the optical status checking. Finally, a polarization independent multiplexer has been implemented and tested. Insertion losses less than 4 dB and isolation better than 23 dB have been measured. In addition, 30-ms and 15-ms setup and rise times have been obtained. The proposed multiplexer can be used in any polymer optical fiber network, even in perfluorinated graded index one, and it can be specially useful in optical sensor networks, or in coarse wavelength division multiplexing networks.     

正交多载波产生技术研究

相干且频率锁定的正交多载波光源产生技术在光通信领域有着诸多应用,能广泛用于微波光子学、全光信号处理以及波分复用(WDM)技术和正交频分复用(OFDM)技术.互联网数据业务的快速增长使得超宽带大容量骨干网传输技术越来越受到世界各国的重视,而要实现Tb/s超大容量传输,目前使用的最主要的方法是光的波分复用(WDM)或正交频分复用(OFDM)技术.作为实现光WDM或OFDM的一项关键技术,相干和频率锁定的正交多波长光源技术引起了国内外各大科研机构的强烈关注.介绍了国内外多载波技术的现状以及多载波产生的多种方案,并对每一个方案进行了对比分析,为未来的研究提供了一些参考.     

应用波分复用技术实现飞秒级超快动态过程的脉冲数字显微全息记录

采用波分复用方法实现飞秒级超快动态过程的脉冲数字显微全息记录和再现。在全息记录过程中,利用BBO倍频晶体对入射激光进行倍频,将基波和谐波分光,并经时间延迟后进入迈克耳孙干涉仪,从而可应用波分复用技术,先后在CCD的一帧图像上记录两张具有不同空间频率的子全息图。采用这种方法,实现了对单脉冲飞秒激光激发空气电离的超快动态过程的全息记录,并通过数字傅里叶变换和数字滤波的方法,分别再现出每张子全息图记录的波前,从而获得了具有飞秒时间分辨的空气等离子体形成和传播过程的动态振幅和相位图像,其单次曝光时间为50 fs,曝光时间间隔为400 fs,相应的曝光频率约为2.5×1012f/s。     

Analytical Model of Non-dispersion-limited Transient Stimulated Raman Scattering in Single-mode Silica Fiber in WDM Optical Communication System

The non-dispersion-limited analytic solutions of unidirectional N-channel transient stimulated Raman scattering (SRS) coupling wave equation which governing the propagation of the optical signals in single-mode (SM) silica fiber have been presented. Taking into account the SRS cross coupling among the N-channels, the analytic solutions are applicable to the system with arbitrary channel separation and input signal light power.     

Analytical Model of Non-dispersion-limited Transient Stimulated Raman Scattering in Single-mode Silica Fiber in WDM Optical Communication System

1 IntroductionNowadays, fused silica fiber still is the most common fiber in wavelength divisionmultipleeing (WDM) OPtical commwhcation syStem. In the WDM system, themodulation type of input signal in one channel differs from another channel. FOrinstance, in the Ralnan fiber amplifiers, the pUmP is a continuous wave (CW) whilethe signals are pulse modulated. SO, when we study the SRS effect in the system, wemust take into account the different modulation type of signals. For a tWO-cha…     

基于波分耦合器的光纤布拉格光栅传感器

为了实现对光纤布拉格光栅传感器的波长解调,使用普通的光纤波分耦合作为波长鉴别器件,将波长的变化转变成光强的变化,并用双路差动放大去除光源强度变化和外界干扰的影响。使用发光二极管(LED)作为光源以降低系统成本,因此使用调制光源和交流放大器对信号进行处理。实验达到约10με的应变测量分辨力和0．2℃的温度测量分辨力。是目前最廉价的光纤布拉格光栅传感器之一。     

光纤光栅和环形器组成的光分插复用器同频串扰特性研究

对三种不同结构的光纤光栅和环形器组成的光分插复用器的同频串扰进行了实验研究。实验表明，与常规的I型结构光分插复用器相比，Ⅱ型和Ⅲ型结构中由上载端泄漏到下载端的同频串扰分别减少了24．4dB和39．3dB，由下载端泄漏到上载端的同频串扰分别减少了23．6dB和24．6dB。     

光纤传输系统中互相位调制和受激拉曼散射串扰噪声的比较研究Ⅱ--级联传输系统

在具有级联光放大器的密集波分复用强度调制一直接检测光纤系统中，导出了包含互相位调制和受激拉曼散射共同作用的强度／相位矩阵表达式。在计算强度噪声谱的基础上，研究了互相位调制和受激拉曼散射的相互耦合并用于密集波分复用系统的噪声分析。在带色散补偿的密集波分复用级联光纤传输系统中(如80信道，信道间距50GHz)，受激拉曼散射引入的串扰噪声功率可能超过互相位调制。最后，给出了密集波分复用系统分析与设计的若干建议。     

光纤传输系统中互相位调制和受激拉曼散射串扰噪声的比较研究Ⅰ--单级传输系统

在密集波分复用强度调制直接检测光纤系统中 ,导出了包含互相位调制和受激拉曼散射共同作用的强度/相位矩阵表达式。在计算强度噪声谱的基础上 ,研究了互相位调制和受激拉曼散射的相互耦合并用于密集波分复用系统的噪声分析。分析表明 ,受激拉曼散射主要引入低频串扰噪声 ,而互相位调制主要引入高频串扰噪声。相邻较近信道引入的串扰噪声主要来源于互相位调制 ,相邻较远信道引入的串扰噪声主要来源于受激拉曼散射。在单级传输 (无色散补偿 )系统中 ,系统性能一般首先受到互相位调制的限制     

A Miniaturized Tunable Filter Based on a Fiber Bragg Grating Loaded by a Ceramic-Tube Microheater

A miniaturized 1.55 μm tunable fiber Bragg grating (FGB) filter is proposed and successfully demonstrated using an aluminum ceramic-tube with a tungsten thick film sleeve microheater. Fine tuning of the Bragg reflective wavelength with 0.0135 nm/^oC is achieved by adding the constant thermal distribution along the uniform FBG with a 0.3 nm bandwidth. Furthermore, a 1.5 nm linearly chirped reflection bandwidth is obtained by thermal gradient loading.     

The Effect of SRS on Signal Power in Single-mode Silica Fiber in DWDM Optical Communication System with Equally Spaced Channels

Assuming that the Raman gain profile of silica fiber is a triangular function, we derive analytic solutions of N-channel steady-state forward SRS coupling wave equation with equal (but arbitrary) channel spacing. Considering the SRS cross coupling among N-channels, the analytic solutions are applicable to arbitrary signal light power. The results point out that the sequence mi=pi(z)/pi(0) [pi(z) and pi(0) is the power of signal light of i-th channel at transmission length z and 0, respectively. i=1,2,...N] maintains a geometric progression with the common ratio q in the transmission process. The common ratio q varies as a exponential function of the effective transmission length, the sum of input light power and the channel spacing, respectively.     

膜厚监控系统的光谱宽度对窄带滤光片性能的影响

讨论了膜厚监控系统的光谱宽度对波分复用窄带滤光片特性的影响,分析了监控过程中所出现的信号异常现象,其主要原因是控制光光谱宽度以及控制波长与滤光片中心波长不一致,所以控制光光谱分辨率必须小于单个法布里-珀罗滤光片最后2层膜折转点波长宽度的一半,即对100GHz的滤光片,监控系统的光谱宽度必须小于0．2nm。一旦产生中心波长偏离,就必定产生厚度控制误差。讨论了高折射率膜和低折射率膜的信号变化规律,发现当中心波长比监控波长长时,虽然信号变化规律正确,但判读到极值时的膜厚变薄。中心波长偏离越长,厚度将越薄。而当中心波长比监控波长短时,信号将出现反转。中心波长越短,反转量越大。最后指出了监控误差对滤光片Tmax和半峰全宽的影响。