High performance silicon waveguide germanium photodetector

High-performance Ge-on-SOI p–i–n waveguide photodetectors with different sizes were fabricated. The performances, in terms of dark-current, photo current responsivity and 3-d B bandwidth, were well studied. A responsivity of 0.842 A/W at 1550 nm and dark current of 70 n A was measured from this detector at-1 V. The detector with a size of4 μm×10 μm demonstrated an optical band width of 19 GHz at-5 V for 1550 nm. Both the experimental results and the finite-difference time domain simulation show that, when the device size is above a certain threshold, the absorption is not sensitively dependent on such designing parameters as the width and length of the photodetector.

中红外硅基光波导的发展现状

作为硅光子集成芯片中基本无源器件的硅基光波导是进行光信号传输的通道,其具有良好的性能,且与CMOS(Complementary Metal Oxide Semiconductor)工艺相兼容因而得到广泛应用。用于电信和数据中心的硅光子集成电路已逐步走向商业化。近年来,中红外波段在自由空间通信、传感以及环境监测等领域的潜在应用受到研究者们的广泛关注。文中分析了中红外硅基光波导的研究现状,归纳了SOI(Silicon on Insulator)、GOSI(Ge-on-SOI)、SOS(Si on Sapphire)、GOS(Ge-on-Si)、SGOS(SiGe-on-Si)、SON(Si-on Si_(3)N_(4))、GON(Ge-on Si_(3)N_(4))等波导材料平台和SOPS(Si on Porous Si)、Undercut、Pedestal、Freestanding、Suspended、LOCOS(Local Oxidation of Silicon)以及等离子体结构等制造工艺平台的研究成果。迄今为止,多数单晶硅在MIR(Mid-Infrared)平台的传播损耗大约在0.7~3.0 dB·cm^(-1)。文中讨论并对比了不同类型波导的应用前景,为中红外硅基光波导的研发、应用和商业化提供了参考。

锗硅脊形光波导Y分支器的模拟及试制

继研制成功单模脊形锗硅合金光波导后，进一步用这种光波导试制Ｙ分支器．文中用束传播法ＢＰＭ首先从理论上分析了波长λ＝１．３μｍ的光波在分支器中的传播特性，模拟计算了模场的传播及损耗．其次叙述了实际锗硅Ｙ分支器的制造工艺及测量结果．结果表明，激光束耦合进锗硅分支器的输入端后，分支器的二路输出端成功输出均匀的单模光波．

Ge_xSi_(1-x)/Si应变超晶格PIN探测器的研制

本文对ＧｅｘＳｉ１－ｘ／Ｓｉ应变超晶格ＰＩＮ探测器进行了分析和设计（其中ｘ＝０．６），并制作出了相应的器件．对典型器件的测试结果表明，在１．３μｍ光照下，反偏电压为－５Ｖ时，光响应电流为２．６μＡ，暗电流为４００ｎＡ，探测灵敏度为０．１５３μＡ／μＷ．最大总量子效率为１４．２％．

一种高性能硅基锗单行载流子光电探测器设计

光电探测器作为光通信系统的核心器件之一,其性能对通信质量起着决定性的作用。随着光通信数据量的剧增,传统的光电探测器已经不能满足需求。文章提出一种集成氮化硅波导的高性能硅基锗单行载流子光电探测器。借助Lumerical FDTD和DEVICE软件进行建模仿真,通过对波导结构以及探测器尺寸进行设计,最终该结构在1 550 nm波长和-1 V偏压下,响应度高达0.97 A/W,光电流线性输出>30 mA,3 dB带宽高达28 GHz。

TWC and AWG based optical switching structure for OVPN in WDM-PON

With the rapid development of optical elements with large capacity and high speed, the network architecture is of great importance in determing the performance of wavelength division multiplexing passive optical network （WDM-PON）. This paper proposes a switching struc^re based on the tunable wavelength converter （TWC） and the ar- rayed-waveguide grating （AWG） for WDM-PON, in order to provide the function of opitcal virtual private network （OVPN）. Using the tunable wavelength converter technology, this switch structure is designed and works between the optical line terminal （OLT） and optical network units （ONUs） in the WDM-PON system. Moreover, the wavelength assignment of upstream/downstream can be realized and direct communication between ONUs is also allowed by privite wavelength channel. Simulation results show that the proposed TWC and AWG based switching structure is able to achieve OVPN function and to gain better performances in terms of bite error rate （BER） and time delay.

Design and fabrication of compact Ge-on-SOI coupling structure

In this paper, we have proposed and demonstrated a simple approach to fabricate vertical integrated structure for coupling between active germanium (Ge) waveguide and silicon-on-insulator (SOI) waveguide. The active Ge waveguide is sputtered after etching the underlying passive silicon (Si) waveguide. This method scuttles away from the difficulty involved in the waveguide fabrication by avoiding the etching process for the Ge waveguide, and thereby the waveguide quality is improved. The influences of the coupling structural parameters on the coupling loss are analyzed and discussed. The optimizing parameters are obtained for the fabrication. The minimal coupling loss is experimentally measured about 2.37 dB, and variation tendency of coupling loss against the structural parameters is consistent with the theoretical result. The proposed approach offers an effective path for vertical coupling between Ge and SOI optical components.

硅基二氧化硅阵列波导光栅制作工艺的研究

硅基二氧化硅阵列波导光栅是集成化波分复用光网络中的核心器件之一。对其制作工艺的研究对提高器件的性能具有重大意义。提出一种在波导上包层使用硼锗共掺高温退火的工艺方法,成功实现阵列波导间空隙的填充,并将阵列波导光栅的插入损耗成功降低约2 dB。相对于传统的硼磷硅玻璃工艺,此方法避免了剧毒气体磷烷的使用,工艺简便安全,同时降低了成本。最后,通过对光刻、增强型等离子体化学气相沉积法(PECVD)薄膜沉积、感应耦合等离子体(ICP)干法刻蚀和高温退火回流等工艺步骤的改进、完善和优化,实现了额外损耗约为1.5 dB的阵列波导光栅。

Broadband directional coupler based on asymmetric dual-core photonic crystal fiber

A novel broadband directional coupler based on an asymmetric dual-core photonic crystal fibet(PCF)is proposed.The asymmetry in the fiher is introduced by the enlargement of one air-hole in dual-core PCF.Numerical investigation demonstrate that broadband directional coupling with spectral width as large as 370 nm and polarization-dependent loss and uniformity lower than 0.2 and 0.5 dB,respectively,can be achieved.In addition,the proposed fiber shows large tolerance to the variation of the fiber parameters.In particular,the fiber length allows at least 10%derivation from the proposed fiber length of 7.7 mm.