渡膜法获得的超辐射发光二极管的特性分析

在考虑了反射率与波长有关这一基本事实后，用图示方法对由镀膜法获得的超辐射发光二极管（ＳＬＤ）的科特性进行了分析。结果表明：在判定减反射膜镀得好与不好的时间，最低反射处波长控制的准确性与最低反射率本身的大都很重要；同时，也可以香到单面镀膜的ＳＬＤ振荡波长与增益峰值波长不重合的现象。     

1.3μm波长超辐射发光二极管组件

光纤陀螺用关键器件之一是超辐射发光二极管（ＳＬＤ）。采用ＳＬＤ作为光源，光纤陀螺可达到高精度、高灵敏度、高稳定性、低噪声的目的。ＳＬＤ是一种以内部单程增益为特征的光发射器件。表征器件性能的主要技术参数指标是输出功率和光谱宽度。通过理论分析和实验，确定了器件的结构，在研制过程中解决了外延生长、端面镀膜等关键技术。组件采用１４针双列直插式管壳、标准单模光纤耦合封装。组件包括ＳＬＤ、光监视用ＰＩＮ光探测器、热敏电阻和半导体致冷器，可通过外电路对组件实现温控、光控，以便组件能长期稳定工作。组件尾纤输出功率大于３００μＷ，最大超过７００μＷ，光谱宽度大于３０ｎｍ。     

分析半导体激光器端面单层减反射膜的有效性

图解辅以计算研究了镀制减反射膜的半导体激光器镀膜面的有效反射。由于减反膜自身反射率曲线的波长依赖性和谱线宽度的有限性,故一般情况下镀膜面的实际反射率比减反膜自身的最低反射率高。针对这种情况,我们进一步讨论了如何通过选择最低反射率所处的波长来提高减反射膜的有效性。     

减反射膜与外腔半导体激光器调谐范围

由于镀了减反射膜的半导体激光二极管端面的反射曲线的谱宽有限，而且，增益峰值波长随载流子密度的变化，因而实际上起作用的反射率通常都比能测到的最低反射率高，在腔内可建立的载流子密度的上限比预期的低。在考虑了这些因素后，计算了用这种管子作外腔半导体激光器（ＥＣＬＤ）的增益介质时，ＥＣＬＤ的调谐范围。     

1．3μmInGaAsP／InPLD，SLD和LED的介质镀膜

简要叙述了介质镀膜对半导体激光器性能的影响。在１．３μｍＩｎＧａＡｓＰ／ＩｎＰ激光器（ＬＤ）、超辐射发光二极管（ＳＬＤ）和发光二极管（ＬＥＤ）上进行了大量的Ａｌ２Ｏ３和ＺｒＯ２减反射膜的工艺研究。结果表明，该减反射膜使激光器阈值电流增加，并将部分激光器变成了超辐射发光二极管。减反射膜还显著地改进超辐射发光二极管的性能，增加其输出功率。它也能导致发光二极管的输出功率的有效增加。     

端镜面镀膜对具有DC－PBH结构的MQW－LD光电性能的影响

报告了具有ＤＣ－ＰＢＨ（双沟平面掩埋异质结构）的ＭＱＷ－ＬＤ（多量子阱激光器）端镜面镀膜对阈值电流Ｉｔｈ和激射波长λｐ的影响。指出：端镜面镀高反射膜ＨＲ（反射率Ｒ２＝７５％～９０％），Ｉｔｈ可降低３．８～５．ｌｍＡ，λｐ加长４ｎｍ左右；端镜面镀增透膜ＡＲ（反射率Ｒ１＝１０％～１５％），Ｉｔｈ将增加３ｍＡ，波长变化趋势不明显。分析和讨论了导致这些变化的物理机理。实验结果和理论计算基本一致。     

端镜面镀膜对具有DC—PBH结构的MQW—LD光电性能的影响

报告了具有ＤＣ－ＰＢＨ（双沟平面掩埋异质结构）的ＭＱＷ－ＬＤ（多量子阱激光器）端镜面镀膜对阈值电流Ｉｔｈ和激射波长γｐ的影响。指出：端镜面镀高反射膜ＨＲ（反射率Ｒ２＝７５％￣９０％），Ｉｔｈ可降低３．８￣５．１ｍＡ，γｐ加长４ｎｍ左右；端镜面镀增透膜ＡＲ（反射率Ｒ１＝１０％￣１５％），Ｉｔｈ将增加３ｍＡ，波长变化趋势不明显。分析和讨论了导致这些变化的物理机理。实验结果和理论计算基本一致。     

弯波导吸收区结构1．3μm InGaAsP／InP超辐射发光二极管的设计

本文用束传播方法（ＢＰＭ）设计了具有弯曲波导吸收区结构１．３μｍＩｎＧａＡｓＰ／ＩｎＰ超辐射发光二极管（ＳＬＤ），分析了不同吸收区长度Ｌａ和弯曲的曲率半径Ｒ对ＳＬＤ特性的影响，给出了直观的结果，并进行了优化设计。在假定吸收区后端面反射率为１，和忽略吸收区内的吸收损耗的条件下，取ｄ＝０．２μｍ，ｗ＝２μｍ，Ｌｐ＝４００μｍ，Ｌａ＝２００μｍ，Ｒ＝５００μｍ，Ｉ＝２００ｍＡ，经吸收区反射耦合回有源区内的光与有源区前端面入射光的强度比率仅为９．５×１０－３。     

具有激光二极管结构的1.3μm侧面发光二极管（Ⅱ）：实验结果

文章给出了用部分参数不合格的激光二极管（ＬＤ）制作具有激光二极管结构的侧面发光二极管＊ＬＤＳ－ＥＬＥＤ）的实验结果。     

1.3μm直条形吸收区超辐射发光管的复折射矢量束传播方法模拟

束传播方法广泛的地无源波导器件的模拟与设计，为了能够模拟有源器件，例如金属包层波导和超射发光二极管（ＳＬＤ），我们将复的射率引入其中，器件的增 吸收通过折射率为描述，用复折射率的有奶差分敌意一束传播方法，我们对１．３μｍ直条形吸收区ＳＬＤ进行了模拟与设计，并且给出一种新结构。     

Analytical model of a superluminescent diode

Using a set of traveling wave rate equations ,a superluminescent diode with a low facet reflectivity is studied .Analytical expressions of the distribu-tions of carrier density ,forward-and backward-propagation photon densities,and gain are obtained at different facet reflectivities.It is shown that the high nonuni-form carrier distribution is evident in the case of low facet reflectivity.The results can serve as useful guides in understanding emission mechanism of superlumi-nescent diodes.     

Analytical model of a superluminescent diode

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Spectral investigation of multimode fiber Bragg grating based external-cavity semiconductor lasers

The output spectra of external-cavity semiconductor lasers (ECSLs) formed by using different antireflection (AR) coated laser diodes (LDs) with multimode fiber Bragg gratings (MMFBGs), are studied systematically. It is found that the side mode suppression ratio (SMSR) of the output spectra of ECSL is dependent on the relative position of the Bragg wavelength and the intracavity modes of the LD, and this effect is more apparent when the reflectivity of AR coating of LD is increased. Numerical simulations are provided to explain the experimental observations. Furthermore, the requirements of wavelength locking of ECSLs with MMFBGs are found to be different from those with single-mode fiber Bragg gratings (SMFBGs). The conditions of wavelength locking of the MMFBG-based ECSLs in terms of gain margin between the material gain peak and the gain corresponding to the selected Bragg wavelength, reflectivity of AR coating of LD and reflectivities of the Bragg wavelengths of MMFBG are comprehensively investigated, and compared with the experimental results.     

Measurement of the Residual Modal Reflectivity of AR Coating on a SLD

ＭｅａｓｕｒｅｍｅｎｔｏｆｔｈｅＲｅｓｉｄｕａｌＭｏｄａｌＲｅｆｌｅｃｔｉｖｉｔｙｏｆＡＲＣｏａｔｉｎｇｏｎａＳＬＤ￥ＭＡＤｏｎｇｇｅ；ＳＨＩＪｉａｗｅｉ；ＬＩＵＭｉｎｇｄａ；ＪＩＮＥｎｓｕｎ；ＧＡＯＤｉｎｇｓａｎ（ＪｉｎｎＵｎｉｖｅｒｓｉｔｙ，Ｃｈ...     

高功率850 nm宽光谱大光腔超辐射发光二极管

超辐射发光二极管(SLD)具有不同于半导体激光器和普通发光二极管的优异性能。为提高半导体超辐射发光管的光谱宽度,采用非均匀阱宽多量子阱(MQW)材料拓宽超辐射器件的输出光谱。优化设计器件的波导结构,利用大光腔结构设计出高功率、低发散角850 nm超辐射发光二极管。采用直波导吸收区而后在器件的出光腔面上镀制抗反射膜的方法制作超辐射发光二极管。器件在140 mA时器件半峰全宽(FWHM)可以达到26 nm,室温下连续输出功率达到7 mW。器件的垂直发散角为28°,水平发散角为10°。由于器件具有比较小的发散角,与光纤耦合时具有比较高的耦合效率,单模保偏光纤耦合输出功率达到1.5 mW。     

一种大功率低偏振度量子阱超辐射发光二极管

设计了一种张应变与压应变相结合的混合应变量子阱结构超辐射发光二极管,研究了TE模和TM模在器件中的模式增益,分析了影响增益偏振性的因素,在此基础上通过改变有源层量子阱的应变类型、应变量以及层数来达到高增益和偏振不敏感性。最后按设计工艺流程生长了芯片,实验结果表明,所设计的SLD芯片单管输出功率在100mA驱动电流下可达3.5mW,出射光谱FWHM约为40nm,20nm波长范围内偏振度为0.3dB,具有较理想的大功率、宽光谱、低偏振度特性。     

External Cavity Lasers Composed of Higher Order Gratings and SLDs Integrated on PLC Platform

Very compact 4‐channel 200‐GHz‐spacing external cavity lasers (ECLs) were fabricated by hybrid integration of reflection gratings and superluminescent laser diodes on a planar lightwave circuit chip. The fifth‐order gratings as reflection gratings were formed using a conventional contact‐mask photo‐lithography process to achieve low‐cost fabrication. The lasing wavelength of the fabricated ECLs matched the ITU grid with an accuracy of ×0.1 nm, and optical powers were more than 0.4 mW at the injection current of 80 mA for all channels. The ECLs showed single mode operations with more than 30 dB side lobe suppression.     

Anomalous wavelength changes of 980-nm pump laser diodes with antireflection coatings

We have observed abrupt wavelength jumps form 980-nm pump laser diodes with an antireflection (AR) coating when the injection currents were changed. The width of the anomalous jumps becomes wider as the cavity length is shortened. It was clarified from theoretical calculations that the phenomenon is caused by narrow mirror loss distributions. It was also confirmed that wide AR coatings or a long cavity can avoid these abrupt wavelength jumps.     

Mode coupling in angled facet semiconductor optical amplifiers andsuperluminescent diodes

The modal reflectivity of an angled facet has been calculated for index-guided devices when the fundamental mode excites various higher order modes at the facet. The calculations were carried out for waveguide widths ranging from 2 to 20 μm for various lateral index steps and at wavelengths of 834, 1300, and 1550 nm. Plots from these calculations can be used to determine the appropriate facet angles to obtain a given modal reflectivity and optimize the design of optical amplifiers and superluminescent diodes     

Measurement of the modal reflectivity of an antireflection coating on a superluminescent diode

A method for measuring the modal reflectivity of the antireflection coating applied to a laser diode is described and demonstrated. It is based on measurements of the Fabry-Perot modulation depth of the resulting superluminescent diode (SLD) output spectrum at the threshold current of the original laser. A modal reflectivity of less than2 times 10^{-4}has been obtained.