对硅基拉曼激光器性能的实验分析

为了解决拉曼激光器的非线性光学损耗严重以及输出效率偏低的问题,利用受激拉曼散射(SRS)的非线性频移机制,以Si元素作为拉曼激光器的增益介质设计了激光器的结构.根据硅元素波导理论,在拉曼激光器的波导结构中设计了一个反向偏置电压的p-i-n二极管,通过控制调节该反向电压值降低有效载流子寿命,从而降低由双光子吸收(TPA)...     

用于喇曼放大的SOI脊形波导中自由载流子寿命的解析表达

研究了用于喇曼放大的绝缘硅(SOI)脊形波导中自由载流子寿命与非线性光学损耗的关系.通过理论推导结合二维数值模拟的方法,提出了带有零反偏pin结构的SOI脊形波导中自由载流子寿命的解析表达式,该解析表达式与他人的实验结果相符.结果表明,比起不带pin结构的波导,带有零反偏pin结构的波导中的自由载流子寿命最多可以缩短80%.同时,研究了pin结构外加反偏电压时,自由载流子寿命进一步缩短的原因,并从强场下自由载流子速度饱和的角度出发,得到了自由载流子寿命的理论极限值.最后,模拟了不同自由载流子寿命情况下SOI脊形波导的喇曼净增益随着输入泵浦光功率密度的变化曲线,为硅基喇曼放大器的进一步研究指明了方向.     

用于喇曼放大的SOI脊形波导中自由载流子寿命的解析表达

研究了用于喇曼放大的绝缘硅(SOI)脊形波导中自由载流子寿命与非线性光学损耗的关系.通过理论推导结合二维数值模拟的方法,提出了带有零反偏pin结构的SOI脊形波导中自由载流子寿命的解析表达式,该解析表达式与他人的实验结果相符.结果表明,比起不带pin结构的波导,带有零反偏pin结构的波导中的自由载流子寿命最多可以缩短80%.同时,研究了pin结构外加反偏电压时,自由载流子寿命进一步缩短的原因,并从强场下自由载流子速度饱和的角度出发,得到了自由载流子寿命的理论极限值.最后,模拟了不同自由载流子寿命情况下SOI脊形波导的喇曼净增益随着输入泵浦光功率密度的变化曲线,为硅基喇曼放大器的进一步研究指明了方向.     

载流子寿命对Si基光电子器件性能的影响

研究了载流子寿命对SOI有源光波导器件工作性能的限制及影响,分析了制约载流子寿命减小的若干因素,综述了采用合理设计减小波导截面尺寸参数、脊区内植入He离子、加入pin结构施加反向偏压等几种有效减少载流子寿命的方法,并给出了它们各自的理论基础和文献报道的理论模拟与实验结果。经过对各种方法的利弊进行分析比较,作者认为在提高光电子器件性能的研究中,采用减小波导截面尺寸参数的方法要同时兼顾传输损耗的变化;采用离子植入法可以在不改变波导尺寸的情况下减小载流子的寿命,但引入了附加损耗且与CMOS工艺不相兼容;而外加pin结构的方法不适用于已经存在电学结构的器件。     

硅基拉曼激光器的研究与进展

硅基激光器实现的问题一直是硅光电集成的主要障碍。实现硅基激光器的有效方法之一是采用拉曼散射原理实现硅基拉曼激光器。本文详细阐述了硅基拉曼激光器的工作原理、波导结构,并介绍了近几年来已经实现的脉冲和连续波拉曼激光器的结构和工作性能。     

大功率双包层光纤激光器拉曼效应分析

受激拉曼散射是大功率光纤激光器性能提升的主要限制之一.采用数值方法深入分析了大功率光纤激光器中的拉曼效应,结果表明,增大信号波长和减小腔镜反射率能有效地减小受激拉曼散射的影响;深入探讨了不同泵浦方式下激光器的拉曼特性,为选取合适的泵浦方式提供了理论依据;首次研究了空间多点泵浦情况下大功率光纤激光器中的拉曼效应,对空间多点泵浦模型中如何优化泵浦方式、合理设置泵浦点功率具有指导意义.     

条形注入式半导体双异质结激光器的侧向波导和侧向模式稳定性

本文首先简要地对注入式条形半导体双异质结激光器的侧向模式导引机制和模式稳定性的基础理论研究和基本实验研究工作作了较为综合的评述和扼要的分析。分析指出,在通常条形双异质结激光器中,侧向波导主要是自由载流子波导。这种自由载流子波导受外界因素(诸如注入电流,受激发射复合等)的影响是相当明显的,这就使得侧向模式不稳定。而且由于自由载流子波导受外界因素影响而发生变化的现象是该结构自身所固有的问题,因此,通常条形双异质结激光器的侧向模式不稳定性是无法采用提高晶片质量或改进工艺技术等方法所能克服的。理论分析实践证明,为获得稳定的侧向模式,必须改进结构,采用具有侧向上刚性的、内建的实折射率波导或刚性的、内建的增益(或损耗)波导的结构。在本文的后半部分,我们较为详细地介绍了“有效折射率(等价折射率)方法”。采用这种方法,我们对SBH激光器的侧向模式导引机制和模式稳定性作了详细的推导和分析。次后,又对PCW,CDH(脊形)等有源区或限制层厚度变化的条形激光器的侧向模式导引机制和模式稳定性问题的分析和计算方法作了简要的介绍,其详细的计算我们将在另外的文章中给出。     

非对称异质波导半导体激光器结构

提出了一种非对称异质波导半导体激光器外延结构,即通过优化选择材料体系和结构厚度,对器件外延层的P侧限制结构和N侧限制结构分别设计,从而降低器件的电压损耗,使其满足高输出功率以及高的电光转换效率的要求.从载流子的输运和限制等微观机制出发,对器件的主要输出特性进行了理论分析和数值模拟,并以此为根据设计和制作了一种1060 nm In Ga As/Ga As单量子阱非对称异质波导结构半导体激光器,并对器件的主要输出特性进行了测试.实验结果表明,非对称异质结构是降低器件的电压降、增大限制结构对注入载流子的限制,提高半导体激光器电光转换效率的有效措施.     

侧向注入的载流子注入型SOI光开关中的热效应分析V

根据热场方程,分析了侧向载流子注入pin结SOI脊波导器件中的热光效应影响,数值分析和实验现象表明,在该类电光子器件中,载流子注入产生的热光效应影响明显,尤其对于SOI材料的小截面脊波导结构。如1000微米调制长度的器件,在正常工作时,温升引起的折射率上升已占总的效应的1/8;同时提出了通过调整电极位置来进行散热的减小热光效应影响的方案。     

LP-MOVPE生长宽波导有源区无铝单量子阱激光器

介绍了无铝激光器的优点,利用LP-MOVPE生长出宽波导有源区无铝SCH-SQW结构激光器.该结构采用宽带隙InGaAlP作限制层,加宽的InGaP作波导层,增加对载流子和光子的限制作用,以克服有铝激光器易氧化和全无铝激光器载流子易泄漏的缺点.制作的条宽100μm、腔长1mm的激光器(腔面未镀膜),激射波长为831nm,室温连续输出光功率达1W.     

SOI波导弯曲损耗影响因素的分析

采用有效折射率方法EIM(effective index method)和二维束传播算法（2D-BPM）对SOI (silicon-on-insulator）波导弯曲损耗的几种影响因素进行了分析. 通过模拟发现弯曲损耗随弯曲半径的增大、波导宽度的增加及内外脊高比的减小而减小. 同时，改进波导结构，例如在弯曲波导外侧刻槽可以减小SOI脊形波导的弯曲损耗.     

Cascaded silicon Raman lasers as mid-infrared sources

It is shown by numerical simulations that cascaded silicon Raman lasers, in which the pump light undergoes multiple Stokes shifts in a silicon waveguide, can efficiently convert near-IR to mid-IR radiation. For pump wavelengths significantly below 2 mum, two-photon-absorption-induced free-carrier absorption degrades conversion efficiency, and the effective carrier lifetime determines the shortest possible pump wavelength     

GaInAsP/InP integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide

A novel GaInAsP/InP integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide (BJB-DBR integrated laser for short) is proposed and demonstrated. In this structure, it is found theoretically that an efficient coupling of 98% between the active and butt-jointed external waveguides is available by matching the propagation constants and the field profiles of both waveguides, which gives relatively larger fabrication tolerance. Prototype BJB-DBR integrated lasers with emitting wavelength of 1.55 ?m were fabricated, and single-longitudinal-mode operation was obtained at room temperature.     

A proposal on coupled waveguide lasers

a new type of optical oscillator, involving coupled waveguide lasers (CWL's) consisting ofNidentical single-mode active waveguides (N = 3,5) coupled with each other is proposed. Oscillation conditions of coupled waveguide lasers, such as threshold and effective length of waveguides, and output powers are examined theoretically, as compared with the conventional single-mode waveguide lasers.     

Reduced spontaneous carrier lifetime in narrow stripe geometry GaAlAs DH lasers

We examined the dependence of spontaneous carrier lifetime on the stripe width in internally striped-planar GaAlAs DH lasers by measuring the turn-on delay time of lasing emission under step current injection. The measured carrier lifetime reduces in narrow stripe lasers. Reasonable interpretation of the results can be given by the increased carrier density at threshold which results from the increasing waveguide loss and the carrier loss by out-diffusion in narrow stripe lasers. There is also given another explicit explanation on the reduced carrier lifetime by using the rate equation.     

Simulation of structural design with high coupling efficiency in external cavity semiconductor laser

For external cavity semiconductor lasers(ECSLs),high coupling efficiency is critical to reducing the linewidth.In this paper,the coupling efficiency between the laser diode and the waveguide grating has been improved,with proposals for its improvement presented,including adding spot-size conversion(SSC)and using a silicon-on-insulator(SOI)waveguide.The results indicate an increase of coupling efficiency from 41.5%to 93.1%,which exhibits an improvement of approximately 51.6%over conventional schemes.The relationship between coupling efficiency and SOI waveguide structures is mainly concerned in this article.These findings provide a new way for the future research of the narrow linewidth of ECSL.     

Tapered polymer single-mode waveguides for mode transformation

This paper presents a tapered polymer waveguide structure for coupling light between optical waveguides with differing geometries. Optical fibers, lasers, and other photonic integrated circuit components can be coupled with tapered waveguides. The polymer waveguide performs a mode transformation between different mode shapes and sizes. For example, the mode transformation can be from an elliptical laser diode mode to that of a circular optical fiber mode. The input and output of a tapered waveguide structure are analyzed, for the case of laser to fiber coupling, in order to determine the effect of misalignments on the coupling efficiency. Adiabaticity in waveguide propagation is discussed. The fabrication of our polymer waveguides is also described     

Impedance characteristics of quantum-well lasers

We derive theoretical expressions for the impedance of quantum-well lasers below and above threshold based on a simple rate equation model. These electrical laser characteristics are shown to be dominated by purely electrical parameters related to carrier capture/transport and carrier re-emission. The results of on-wafer measurements of the impedance of high-speed In_0.35Ga_0.65 As/GaAs multiple-quantum-well lasers are shown to be in good agreement with this simple model, allowing us to extract the effective carrier escape time and the effective carrier lifetime, and to estimate the effective carrier capture/transport time