Waveguide external cavity narrow linewidth semiconductor lasers

Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs.

Cavity-Mode Properties of Semiconductor Lasers Operating in Strong-Feedback Regime

This paper investigates the modal properties of semiconductor lasers operating in the strong-feedback regime. Analytical expressions are developed based on an iterative travelling-wave model, which enable a complete and quantitative description of a compound cavity mode in its steady state. Additional information is provided about the physical inside into a compound laser system, such as a bifurcation diagram of the compound cavity modes for full variation range （from 0 to 1） of the external reflection coefficient and a more general shape for the diagram of photon density versus mode phase - this latter will reduce to the classical ＂ellipse＂ in the weak-feedback regime. It is shown that in the strong-feedback regime, a feedback laser is characterized by a small mode number and a high density of photons. This behavior confirms previous experimental observations, showing that beyond the coherence-collapse regime, the compound laser system could be re-stabilized, and that as a result power-enhanced low-noise stable laser operation with quasi-uniform pulsation is possible with external-mirror reflectivity close to 1. Moreover, it is also shown that for a compound system operating in the strong-feedback regime, an anti-reflection treatment of a laser can significantly reduce its current threshold, and that in the absence of this treatment excitation of a minimum-linewidth mode with higher output power would be possible inside such a system. Finally, it is shown that in the weak-feedback regime except for a phase shift the iterative travelling-wave model will reduce to the Lang-Kobayashi model in cases where the product of the feedback rate and the internal round-trip time is much less than unity （that would mean in situations of as-cleaved lasers）.

Numerical Simulation of External-Cavity Distributed Feedback Semiconductor Laser

We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .

Semiconductor Optical Amplifier and Gain Chip Used in Wavelength Tunable Lasers

The design concept of semiconductor optical amplifier(SOA)and gain chip used in wavelength tunable lasers(TL)is discussed in this paper.The design concept is similar to that of a conventional SOA or a laser;however,there are a few different points.An SOA in front of the tunable laser should be polarization dependent and has low optical confinement factor.To obtain wide gain bandwidth at the threshold current,the gain chip used in the tunable laser cavity should be something between SOA and fixed-wavelength laser design,while the fixed-wavelength laser has high optical confinement factor.Detailed discussion is given with basic equations and some simulation results on saturation power of the SOA and gain bandwidth of gain chip are shown.

Self Mixing Fringes of Vertical-Cavity Surface-Emitting Lasers under Dual Reflector Feedback

The self-mixing fringes which shift due to every one-twentieth wavelength displacement of the target are observed. Taking advantage of the dual reflectors in the external cavity of lasers, the resolution of the sensors has been improved by 10 times. The role of the each reflector has been discussed in detail.

Steady-State Behavior of Semiconductor Laser Diodes Subject to Arbitrary Levels of External Optical Feedback

This paper investigates the steady-state behavior of a semiconductor laser subject to arbitrary levels of external optical feedback by means of an iterative travelling-wave (ITW) model. Analytical expressions are developed based on an iterative equation. We show that, as in good agreement with previous work, in the weak-feedback regime of operation except for a phase shift the ITW model will be simplified to the Lang-Kobayashi (LK) model, and that in the case where this phase shift is equal to zero the ITW model is identical to the LK model. The present work is of use in particular for distinguishing the coherence-collapse regime from the strong-feedback regime where low-intensity-noise and narrow-linewidth laser operation would be possible at high feedback levels with re-stabilization of the compound laser system.

高功率1150 nm垂直外腔面发射半导体激光器

针对目前激光医疗、食品药品检测等领域对橙黄色激光的应用需求,开展了高功率基频光1150 nm垂直外腔面发射半导体激光器(VECSEL)研究。提出激光谐振腔内大尺寸基模光斑外腔结构,使VECSEL腔内模式匹配较大泵浦光斑尺寸,实现了高功率激光输出;提出增益峰-腔模失谐结构,增益峰与腔模温漂系数不同,高泵浦功率下具有良好的增益峰-腔模匹配,实现高泵浦功率工作下的激光波长稳定控制。制备的VECSEL器件在1150 nm激光波长的输出功率达到9.38 W,并获得良好的圆形对称的输出光斑形貌,光斑在正交方向上的发散角分别为7.3°和7.5°。

基于束腰劈裂偏振合束高亮度窄线宽半导体激光器

将一个808 nm宽发射区半导体激光器应用于纵模选择束腰劈裂偏振合束外腔中,实现了高光束质量、高亮度和窄线宽的激光输出。所获激光输出功率为5.08 W,快慢轴光束质量M2=1.85×18.2,慢轴光束质量较自由运转激光器提高48%,输出激光亮度B=22.74 MW·cm^(-2)·sr^(-1),是原激光器自由运转的1.3倍。所获激光光谱线宽为0.47 nm,压缩至原激光器自由运转的光谱宽度的0.14。

A self-seeded fiber laser incorporated with a fiber Bragg grating external cavity semiconductor laser

A self-seeded fiber laser incorporated with a fiber Bragg grating external cavity semiconductor laser (FBG-ECL) and a Mach-Zehnder interferometer (MZI) were reported in this paper. The MZI provided a Q-switching with response time in the order of micro-seconds. The FBG-ECL provided narrow pulses as seeds to shorten the Q-switched pulses. Experimentally, pulse width of 0.8 μs was measured, which was one fifth of the pulse width without self-seeding.

基于外腔反馈的可调谐半导体激光光源的扫频特性研究

半导体激光光源在激光雷达、空间探测以及光纤智能感知等领域有着重要作用,其中可调谐半导体激光光源还可用于新一代可重构光分插复用系统中光器件等的波长相关和偏振依赖损耗测试。基于Litt-man结构的外腔反馈型可调谐半导体激光光源是一种实现宽调谐、高光谱纯净度和无跳模谐振输出的有效手段。笔者团队利用联合研制的中心波长为1526.276 nm、3 dB带宽为111.0054 nm的增益芯片作为内腔种子源,通过闪耀光栅将不同波长锁定在振荡器中,实现了最快扫描速度为200 nm/s、最小触发间隔为5 pm、本征线宽小于10.02 kHz及无跳模范围为130 nm的单纵模扫频输出。结果表明,凭借InGaAsP/InP增益芯片优异的宽光谱光学特性和Littman反馈原理,本研究结果有助于推动波长快速扫描测试系统的研究进程,提升相关器件测试的精度和效率。

Variation of Lasing Wavelength of Fiber Grating Semiconductor Laser with Temperature for Different External Cavity Lengths

For different external cavity lengths, lasing wavelength variation of fiber grating external cavity semiconductor laser (FGECSL) with ambient temperature has been investigated theoretically, and the theoretical results are in agreement with reported experimental observations.

920nm光抽运垂直外腔面发射半导体激光器结构设计(英文)

设计并优化了一种用808nm的大功率激光二极管为抽运光源,In0.09Ga0.91As量子阱结构为增益介质的920nm光抽运半导体垂直外腔面发射激光器。运用有限元方法,对激光器的电特性方程和光特性方程求自洽解,计算了器件各种特性参量。分析了单个周期内不同阱的个数(1,2和3)、不同阱深、不同垒宽、不同非吸收层组分、不同非吸收层尺寸条件下,器件性能的改变,特别是模式、阈值和光-光转换效率的改变,从而选择一个最佳的结构。

窄线宽的外腔半导体激光器

介绍了使用闪耀光栅作为光反馈元件 ,与原始线宽大于 12 0 0GHz的半导体激光器构成的Littrow型外腔半导体激光器 ,极大地改善了激光器的性能。实验得到了功率恒定、模式单一稳定、线宽优于 1.2MHz的激光输出 ,压窄线宽比为 10 6,并针对Littrow型外腔结构提出了简洁。

980nm OPS-VECSEL关键参数的理论分析

光抽运半导体垂直外腔面发射激光器(Optically Pumped Semiconductor Vertical External Cavity SurfaceEmission Laser)的输出特性受到诸多参数的影响,理论分析和模拟显得尤为重要。设计了一种以808 nm二极管激光耦合模块为光抽运光源,In0.159Ga0.841As/GaAs0.94P0.06为增益介质的980 nm光抽运垂直外腔面发射激光器,并借助于PICS3D软件计算了器件各种特性参数。分析了芯片半径、量子阱的周期数以及外腔镜反射率对器件性能的影响,特别是对阈值和光-光转换效率的影响。模拟结果表明,器件的半径影响光-光转换效率。量子阱个数和外腔镜反射率对器件的输出功率和光-光转换效率都有影响,所以要根据实际需要,设计、生长结构和进行实验。

外腔半导体激光器的设计与高次谐波稳频

首先讨论了半导体激光器外腔结构参量对激光连续可调范围影响的理论计算方法,给出了Littrow结构外腔半导体激光器调谐范围的计算结果。然后介绍了半导体激光器外腔结构参量的具体设计,利用该设计得到了出射激光线宽小于1MHz、连续可调谐范围可达3GHz的780nm波段外腔半导体激光器。接着讨论了利用腔外饱和吸收谱的三次谐波稳频方法对半导体激光器进行稳频,优化激光频率短期稳定度的方法。最后根据该优化方法设计出稳频系统对半导体激光器进行稳频,得到了稳定度达到10-12量级的半导体激光输出。

外腔半导体激光器动态模稳定性的研究

为了研究调谐过程中外腔半导体激光器的模稳定性,采用多光束干涉理论推导Littrow结构外腔半导体激光器的腔增益,并模拟其模结构。分析了光栅面和转臂不在同一平面的情形下,在光栅转动调谐时,通过匹配光栅的反馈波长变化率与外腔波长变化率,推导出最佳的初始外腔长度,并研究了动态模稳定(无跳模调谐)的范围;采用严格的耦合理论和光线变换矩阵分析了准直(耦合)透镜的位置对系统后向耦合效率的影响。结果表明,系统后向耦合效率最大可达99%,极大地压窄了中心波长为780nm半导体激光器的线宽,外腔半导体激光器的理论线宽为未加外腔时的0.96%,动态模稳定范围可达6.8nm。

调谐外腔半导体激光器输出双稳环的确定

在考察了外腔半导体激光器 (ECLD)的振荡频率ν与激光二极管 (LD)中载流子密度N(或增益 g)、介质的折射率n以及LD第m个模式的共振频率νm 间的关系之后 ,利用微扰法对LD的N ν曲线上被前人错判为不稳定的两个关键区段重新进行了分析 ,结果表明这两个区段是稳定区段 ,据此 ,可以确定在对ECLD进行调频的过程中其增益介质的N ν曲线上出现的双稳环。

光纤光栅外腔半导体激光器的理论及实验研究

对影响光纤光栅外腔半导体激光器特性的几个重要因素(光纤光栅长度、耦合系数、内腔反射系数)进行了理论分析和数值模拟。从实验上进行了验证,实测了不同反射率情况下激光器的激射光谱,得到了带宽为0.1nm、出纤功率达417.4μW、边模抑制比高达37.9dB的激光谱线。验证的结果表明,理论分析、数值模拟、实验结果是吻合的。

半导体可饱和吸收镜实现超短高功率脉冲激光研究进展

介绍了半导体可饱和吸收镜(SESAM)的基本结构及使用半导体可饱和吸收镜被动锁模固态激光器的基本原理。综述了利用半导体可饱和吸收镜被动锁模薄片式固态激光器及光泵浦垂直外腔面发射半导体激光器,获得高平均输出功率超短脉冲的最新进展,并指出量子点半导体可饱和吸收镜的使用将加速超短高功率脉冲的发展。

外腔半导体激光器的实验研究

本文报道了外腔半导体激光器的一些研究成果 .利用闪耀光栅作反馈元件 ,对 80 8nm波长的半导体激光器形成弱耦合外腔 ,实现了光谱特性较好的窄线宽单模激光输出 ,线宽小于 0 .0 6nm,边模抑制比大于 30 d B,最大输出功率为 35 .4 m W,总的光—光转换效率为 4 6% .通过调整光栅转角 ,可以得到 1 1 .66nm的波长调谐范围 .设计了光栅 -反射镜联动结构 ,使外腔半导体激光器的输出方向不再随调谐而变化 .