InP‐Based Polarization‐Insensitive Planar Waveguide Concave Grating Demultiplexer with Flattened Spectral Response

InP‐based planar waveguide 48‐channel concave grating demultiplexers with a channel spacing of 0.8 nm (100 GHz) are described and demonstrated. Polarization insensitivity and flattened spectral response are successfully achieved by the introduction of a polarization compensator and a two‐focus grating, respectively. The fabricated device shows a polarization‐dependent wavelength shift of less than 20 pm and a ?3 dB spectral width of about 0.55 nm (68.75 GHz) over all channels.     

平坦功率输出的宽带波长可调光纤环型激光器

为了获得一种平坦功率输出的宽带波长可调的掺铒光纤环型激光器,提出采用一高双折射光纤环镜获得其平坦功率输出,在高双折射光纤环镜中,采用了大量的高双折射光纤段和偏振控制器,它们的反射光谱可补偿掺铒光纤环型激光器输出功率光谱的不平坦,通过压缩或者延伸激光腔里的分布式光纤布喇格光栅即可实现波长调谐。实验验证可以获得一种宽达38nm的宽带波长调谐(1527nm～1565nm),输出功率的不平坦被控制在±0．8dB范围之内,总输出功率大约4dBm、3dB线宽为0．01nm、旁瓣抑制比为48dB的光纤环型激光器。     

宽带偏振不灵敏张应变InGaAs半导体放大器光开关

研制了一种张应变准体InGaAs半导体放大器光开关.该结构具有显著的带填充效应,从而导致在80mA的注入电流下,器件的3dB光带宽大于85nm(1520～1609nm).该带宽几乎同时全部覆盖了C带(1525～1565nm)和L带(1570～1610nm).最为重要的是,在3dB光带范围内,光开关的偏振灵敏度小于0.7dB;光纤到光纤无损工作电流在70～90mA之间;消光比大于50dB.通过降低了载流子寿命,开关速度有所提高.在未来密集波分复用通信系统中,这种宽带偏振不灵敏半导体放大器光开关很有实用前景.     

Ultrawide Bandwidth Wavelength Monitor Based on a Pair of Tilted Fiber Bragg Gratings

A wavelength monitor based on a pair of tilted fiber Bragg gratings is reported. The monitor exhibits a subpicometer wavelength selectivity over a broad wavelength range (>30 nm), and a low insertion loss (<1 dB) for laser light with polarization matching the reference polarization of the device. Simulations show that a wavelength coverage up to 100 nm is possible and that the resolution degradation due to changes in the polarization state can be avoided by proper design of the gratings.     

Single-mode fused biconical coupler optimized for polarizationbeamsplitting

A single-mode fused biconical coupler for polarization beamsplitting is described. In the coupling region, standard communication fibers are used. The output fibers are polarization-maintaining. To stop the coupler drawing process accurately, the degree of polarization is measured during the drawing and is used as a criterion. Losses of 0.2 dB are typical, and a minimum extinction ratio of -27 dB is achieved. A usable spectral window as broad as 17 nm with an extinction ratio smaller than -15 dB for both output fibers is obtained. Any specified wavelength for the minimum of the extinction ratio is reached within ±3 nm     

采用半导体光放大器的多波长光纤环形激光器

报道了一种插入马赫-曾德尔(M-Z)光纤干涉仪的半导体光放大器(SOA)多波长光纤环形激光器,实现了信道间隔为100 GHz的稳定的多波长连续光激射,其输出光谱3 dB带宽为19.5 nm,消光比大于30 dB.其中在17.9 nm范围内获得了22个波长的连续光,功率不平坦度为1.2 dB,总输出功率为5.1 dBm.对该结构的多波长激光器输出光谱宽,不同波长间功率波动小的特性进行了分析,提出在较低环腔损耗下,半导体光放大器的增益饱和及四波混频(FWM)效应的共同作用使环腔内多波长光功率获得自动均衡;并对实验观测到的激光器输出光谱带宽及中心波长随半导体光放大器驱动电流降低或环腔损耗增大而减小的现象进行了讨论.     

Accurate spectral characterization of polarization-dependent loss

Building on previous work, a rapid automated nonmechanical measurement system for spectral characterization of polarization-dependent loss (PDL) has been developed. A deterministic fixed-states Mueller-Stokes method in conjunction with realtime calibrated spectral information is used to derive wavelength-dependent Mueller matrix elements. Voltage-modulated liquid-crystal variable retarders set the input polarization states. A narrow voltage-tuned filter provides a wavelength sweep following a broadband source; the sweep wavelength is calibrated in realtime by hydrogen cyanide reference lines. This rapid measurement system can measure PDL over a wavelength range of 15 nm in 5 s. A complete uncertainty analysis has been conducted for PDL in the range of 0.05 to 0.3 dB with an expanded uncertainty of 0.0098 dB over the range of 1535 to 1560 nm. Performance was verified using a Fresnel reference. Finally, design and performance results from all-fiber artifact calibration standards are presented.     

耗散孤子和束缚态脉冲可切换的超连续谱产生

当超短脉冲进入高非线性光纤时,在色散和非线性效应的共同作用下,脉冲频谱中会产生一些新的频率分量,使得输出频谱比输入频谱宽得多。这种光谱被称为超连续谱。超连续谱光源具有光谱范围宽、方向性好、亮度高、空间相干性好等优点。在锁模激光器中,传统孤子、耗散孤子和类噪声脉冲可以作为种子源产生超连续谱。文中,笔者建立了一个NPR被动锁模光纤激光器来产生脉冲激光。然后,添加一段DCF以补偿腔中的色散,从而产生耗散孤子。同时,通过调节腔内PC,可以实现束缚态和耗散孤子的状态切换。输出脉冲经10 m单模光纤压缩后注入部分拉锥后的高非线性光纤以产生超连续谱。实验中,我们得到了脉宽为5.6 ps、重复频率为32 MHz、信噪比为52 dB的耗散孤子锁模脉冲,压缩后的脉冲宽度为868 fs,用作超连续谱产生。超连续谱的覆盖范围约为1200~2200 nm,其20 dB谱宽为357 nm。通过调节偏振控制器,实现耗散孤子脉冲与束缚态脉冲之间的切换,束缚态脉冲持续时间为1.4 ps,脉冲间隔为14 ps,信噪比为51 dB,产生1600~1870 nm的超连续光谱,20 dB的光谱宽度为135 nm。     

Polarization-insensitive quantum-well semiconductor opticalamplifiers

Theoretical modeling and fabrication of polarization-insensitive semiconductor optical amplifiers that use a multi-quantum-well structure as the gain media are reported. Polarization insensitivity of gain is achieved through the introduction tensile strain into the quantum wells. Gain calculations, using the k·p method, were performed to obtain the required amount of tensile strain to obtain polarization insensitivity over a wide energy spectrum. Fabricated amplifiers show a polarization-insensitive (<1 dB) spectral width of 10 nm at 1300 nm in the InGaAsP/InP system, 15 nm at 1300 nm in the AlInGaAs/InP system, and 40 nm at 1550 nm in the AlInGaAs/InP system     

Multiwavelength pulse generation using an actively mode-locked erbium-doped fiber ring laser based on distributed dispersion cavity

A simple design of a stable multiwavelength pulse generator was demonstrated using a dispersion-tuned actively mode-locked erbium-doped fiber (EDF) ring laser with distributed dispersion cavity. The distributed dispersion cavity in the fiber laser successfully reduced the cross-gain saturation in EDF, and thus, enabled multiwavelength operation. Simultaneous generation of wavelength-tunable 10-GHz pulses up to four different wavelengths was achieved with the same wavelength space of 2.94 nm. The extinction ratio of all wavelengths was above 30 dB. In addition, smooth wavelength tuning was achieved over more than 41 nm when the laser was working at dual-wavelength mode. The super mode noise was /spl sim/60 dB below the signal level at both wavelengths. The laser state was found to be very stable.     

1.3 μm InGaAsP低电流超辐射发光二极管组件

设计并制作了用于高精度光纤陀螺的 1.3μm低电流超辐射发光二极管组件。采用隐埋异质结结构 ,实现了良好的电流限制和光限制 ,同时采用长腔结构来提高器件单程增益 ,从而获得了高的输出功率。组件具有工作电流小、输出功率高 ,以及光谱特性好等特点。测试结果表明 ,在 70mA工作电流下 ,组件尾纤输出功率大于 0 .1mW ,光谱宽度大于 30nm。     

表面光栅垂直腔面发射激光器偏振特性研究

研究了表面光栅结构对垂直腔面发射激光器(VCSEL)的偏振控制作用。引入表面光栅后,对不同刻蚀深度下的偏振相关的镜面损耗进行了仿真,结果表明表面光栅刻蚀深度在44~130 nm范围内均可实现稳定偏振,具有较大的工艺容差。表面光栅VCSEL在基横模工作状态下偏振抑制比(Orthogonal Polarization Suppression Ratio, OPSR)超过20 dB,偏振光谱峰间偏振抑制比达到40 dB,且在多横模状态也实现了有效的偏振控制。为了进一步验证光栅对偏振控制的效果,制作了方向互相垂直的两种表面光栅,具有这两种方向光栅的VCSEL的OPSR均达20 dB以上。测试分析表明表面光栅是VCSEL实现稳定偏振的一种有效手段。     

Experimental analysis of a broadly tunable InGaAsP laser with compositionally varied quantum wells

Custom-designed InGaAsP lasers have been fabricated, tested, and show a broad spectral output at a bias current of 240 mA. The Fabry-Perot ridge waveguide lasers were grown with one 80-/spl Aring/ and five 100-/spl Aring/ quantum wells in the active region. A different material composition was used for each well and this provided contributions to the gain profile over a broad wavelength range. A 1400-/spl mu/m cavity length laser was found to operate in the spectral region from 1475 to 1650 nm and single-mode operation on the individual Fabry-Perot modes of the uncoated laser was achieved over a 172-nm tuning range using a diffractive optical element short external cavity. The side-mode suppression ratio was measured to be above 30 dB at all wavelengths within the tuning range. Complete spectral coverage, in overlapping short segments, with the device is possible using temperature tuning.     

Tuning performance and spectral selectivity of widely tunablevertical Mach-Zehnder lasers

The filtering mechanism, spectral selectivity, and tuning performance of the vertical Mach-Zehnder (VMZ) laser diode are studied. Wavelength selection in this device is due to the interference of two modes with different and electronically controllable optical path lengths in analogy to a common Mach-Zehnder interferometer. Different design approaches for the VMZ laser are investigated. The calculations presented show that tuning ranges between 50 nm and 100 nm with side-mode suppression ratios (SSR's) of more than 20 dB are feasible. Designs with tuning ranges of about 35 nm show SSR values of over 30 dB at the 1.55 μm wavelength enabling the realization of widely tunable laser diodes with full wavelength access within the tuning range, suitable for applications in optical communication systems     

频域光存储偏振极化成孔动力学的研究

报道用偏振光谱对频域存储有机材料ＴＨＰ／ＰＭＭＡ进行持久性光谱烧孔，获得了一般方法难以得到的４００％以上孔深的各向异性孔。着重讨论固体偏振光谱烧孔理论及快速成孔机理，并在实验上观察到各向异性成孔动力学过程，理论和实验上得到很好的拟合。展示了偏振光谱烧孔技术在频域光存储和固体高分辨光谱应用的良好前景。     

宽角扫描的圆极化相控线阵

设计了一款宽波束的圆极化天线单元以及1×4的天线阵列，实现了一维的宽角圆极化扫描.天线单元由单层的辐射贴片和介质基片集成波导（substrate integrated waveguide，SIW）背腔构成，通过在辐射贴片上切角微扰和开U型槽实现右旋圆极化，并利用SIW背腔缝隙展宽波束.同时利用SIW背腔减小阵列单元间的互耦，实现宽角圆极化扫描.仿真与测试结果表明，天线阵列实现了扫描角为-53°~57°，3 dB波束宽度覆盖范围为-76°~79°，在主波束扫描覆盖范围内轴比（axial ratio，AR）均小于3 dB，且在扫描范围内增益变化平稳，可实现良好的宽角范围的圆极化扫描特性.     

室温稳定多波长光纤激光器技术的研究新进展

室温稳定的多波长光纤激光器( MWFL)中最关键的技术是如何有效抑制掺杂光纤的均匀展宽效应。综述了国际上近年来提出的实现室温稳定多波长光纤激射的主要技术。介绍了近几年我们在该领域的一些创新性研究工作:提出了多种基于多谐振峰的光纤布拉格光栅(FBG) ,如多模光纤布拉格光栅、保偏光纤布拉格光栅、取样光纤布拉格光栅等的可开关多波长光纤激光器的新方法和新结构,实现了多种波长间隔小于2 nm,室温工作稳定性好、波长及波长间隔可调的可开关多波长光纤激光器;提出了基于非线性光纤环镜( NOLM)和非线性偏振旋转(NPR)效应的两种多波长掺铒光纤激光器(EDFL)实现技术,实现了室温稳定、功率谱分布平坦的宽带多波长激光输出,3 dB带宽内的波长个数可达50个,每个波长的功率波动在2 h内小于0 .1 dB。     

窄线宽多波长掺铒光纤激光器

在掺铒光纤线型的单模光纤腔中接续一段多模光纤 ,依靠多模光纤中导模的空间模式跳动与激光谐振腔中的偏振烧孔共同作用 ,实现了窄线宽多波长的同时激射。激射波长的 3d B线宽约为 0 .0 9nm ,波长间隔为 0 .6 8nm。     

一种新型高性能光电探测器结构的研究

近来获得极大发展的谐振腔光电探测器具有引人注目的波长选择特性，并且实现了器件量子效率与带宽的渡越时间分量之间的解耦。     

Polarization independent InP WDM multiplexer/demultiplexer module

We report the design, fabrication, packaging, and characterization of a polarization independent integrated optical InP multiplexer/demultiplexer module. The device is based on a vertically etched diffractive grating and separates four channels with 4 spacing in the 1.55 μm window. An n^-/n⁺-InP layer structure with very low birefringence results in a shift of the passbands between transverse electric (TE) and transverse magnetic (TM) polarization of less than 0.1 nm. With a self-aligned flip-chip mounting technique light is optically coupled from the input and output waveguides to an array of lensed single mode fibers with a coupling efficiency of more than 80%. The packaging includes temperature control that allows fine tuning of the channel passbands over 5 nm. Optical crosstalk is always better than -17 dB and fiber to fiber losses of 15 dB are achieved. The module has been successfully implemented in a 4×2.5 Gb/s WDM transmission system