硅基氮化镓波长可调DFB激光器的模拟分析

基于严格耦合波以及介质平板波导理论,构建了硅基氮化镓分布反馈激光器的二维稳态物理模型。且利用多物理场直接耦合分析软件Comsol Multiphysics求解波动方程,得到了分布反馈激光器在可见光各波段形成单模输出的电场模一维、二维图谱,以及相对应的入射波长与电场模关系曲线。结合硅基光微机电系统技术和微加工技术,本文提出利用悬空的自支撑氮化镓周期可调光子光栅实现分布反馈激光器波长可调。数值模拟表明,在光栅的格子数目、光栅厚度、光栅宽度以及有源层厚度一定的情况下,改变光栅周期可以实现分布反馈激光器输出不同波长激光。理论分析与仿真结果基本一致,证明所建立激光器模型具有一定的合理性,得出的仿真数据为实现分布反馈激光器波长可调提供了有意义的参考。     

基于氮化铝的1310nm波段可调DFB激光器的设计

依据严格耦合波理论和介质平板波导理论,基于MEMS(微机电系统)技术,利用周期可调谐的布拉格光栅设计了一种基于氮化铝的波长可调DFB-LD(分布反馈激光器)。采用梳齿状驱动器驱动光栅动态调节,并利用有限元软件COMSOL对其在1 310nm波段进行模拟仿真。对激光器电场模式图进行分析,确定了DFB-LD的光栅结构参数。分析表明,激光器输出波长与光栅周期呈线性关系,且一个光栅周期对应多个不同的光栅高度值。在小于模式截止光栅高度的情况下呈20nm周期性分布。依据光栅周期和激射波长的关系,提出了制作1 290~1 330nm波段可调激光器的可能性。     

氧化锌单晶DFB半导体激光器的设计与分析

基于严格耦合波理论(RCWA)和介质平板波导理论,针对光通信中的1550 nm波长,设计了一种基于氧化锌(ZnO)单晶的分布反馈式(DFB)半导体激光器的光栅结构,分析了二维电场模式图以及激射波长线宽图,得到了光栅结构的变化对其单纵模传输的影响。仿真结果表明,当光栅的周期为489 nm,占空比为50%,光栅深度为400 nm时,全局电场能量达到了8.3×107 J,光谱线宽小于0.1 。该激光器具有很好的窄线宽输出以及波长选择特性。理论分析与仿真结果基本一致为后期进行该器件的制备提供了较好的参考。     

光纤通信用光源亮点凸现

(上接12期) WDM用光源 用于WDM系统的波长可控光源、波长可调光源和多波长光源是目前研究的重点。对应用于WDM系统光源的要求是发光波长必须精确、稳定、可靠性高、成本低、便于集成、并有与之配套的波长监测与稳定技术。目前,已开发了多波长光源、绝对波长光源、分布反馈型激光器和超级周期结构衍射光栅分布反馈型激光器等波长可调半导体激光器以及多波长光纤环形激光器等。     

全息光刻制备LC-DFB及光栅刻蚀优化

成功制备出室温激射波长为2 μm的GaSb基侧向耦合分布反馈量子阱激光器.采用全息曝光及电感耦合等离子体刻蚀技术制备二阶布拉格光栅.优化了光栅制备的刻蚀条件,并获得室温2 μm单纵模激射.激光器输出光功率超过5 mW,最大边模抑制比达到24 dB.     

975nm分布反馈激光器一级光栅的制备

优化设计了975 nm分布反馈激光器的一级布拉格光栅结构.将纳米压印技术与干法刻蚀工艺相结合制备周期为148 nm的光栅结构,通过优化调整刻蚀气体流量比、腔室压强和偏压功率等参数,得到了合适的光栅刻蚀工艺参数.扫描电子显微镜测试显示,光栅周期为148 nm,占空比接近50％,深度合适,表面形貌、连续性和均匀性良好.将所制备光栅应用于975 nm分布反馈激光器中,激光器输出性能良好,波长随温度漂移系数小,光栅对波长的锁定效果良好.     

全息光刻制备LC-DFB及光栅刻蚀优化（英文）

成功制备出室温激射波长为2μm的Ga Sb基侧向耦合分布反馈量子阱激光器.采用全息曝光及电感耦合等离子体刻蚀技术制备二阶布拉格光栅.优化了光栅制备的刻蚀条件,并获得室温2μm单纵模激射.激光器输出光功率超过5 m W,最大边模抑制比达到24 d B.     

外腔半导体激光器激射波长温度稳定性的研究

在考虑了光纤光栅(FG)的相位分布之后,根据光纤光栅外腔半导体激光器(FGESL)所满足的阈值条件,从理论上研究了前端面反射率对光纤光栅长外腔半导体激光器(LECFGSL)激射波长温度稳定性的影响.数值模拟的结果表明:随着温度的变化,LECFGSL的激射波长围绕光栅布拉格反射波长上下波动,激光器前端面反射率对激射波长波动幅度有较大的影响,当前端面反射率＜10-4时,激射波长与光栅布拉格反射波长基本一致,其温度稳定性较好.     

采用模拟PID控制的DFB激光器温度控制系统研制

以红外分布反馈激光器激发光源为核心的检测装置中,分布反馈激光器发光波长的控制精度及稳定性直接决定检测装置测量准确性。为此研发了一种采用模拟PID控制的分布反馈激光器温度控制系统。该系统采用模拟比例-积分-微分温度前向控制模块和温度实时后向采集模块达到控制温度的目的。温度控制实验中采用激射中心波长为2 049 nm的分布反馈激光器,结果表明,系统温度控制稳定性为0.05℃,稳定时间小于30 s。同时,利用所研制的温度控制系统对上述可调谐DFB激光器做了光谱测试实验,结果表明,当激光器驱动电流固定时,激光器激射波长与其工作温度呈线性关系。     

光反馈对光纤光栅外腔半导体激光器特性的影响

主要研究了外加光反馈对光纤布拉格光栅外腔半导体窄线宽激光器特性的影响。在研究温度对光纤光栅外腔半导体激光器激射波长影响的基础上,设计了强度可调的外加光反馈系统,并利用延时自外差法测试外腔半导体激光器的线宽,从实验上分析了不同强度的外加光反馈对外腔半导体激光器线宽和噪声的影响。实验结果表明,在外加光反馈强度逐渐增强的过程中,激光器线宽逐渐变窄。当反馈比为-22dB时,激光器线宽被压窄至原始线宽的15%。与此同时,在相同的反馈变化下,激光器的相对强度噪声开始无明显变化,直到反馈比达到-27dB。再继续增大反馈强度,相对强度噪声显著增大,激光器内部发生相干崩塌。     

Electrical control of the distributed feedback organic semiconductor laser based on holographic polymer dispersed liquid crystal grating

In this paper, we demonstrate the electrical control of the distributed feedback (DFB) organic semiconductor laser based on a holographic polymer dispersed liquid crystal (HPDLC) grating for the first time. The grating is fabricated on the top of the organic semiconductor film to act as an external feedback structure. Experimental results show that the lasing intensity can be decreased by increasing the external electric field, and the lasing wavelength exhibits a slight blue-shift of 1.4 nm during the modulation process, indicating a good stability. The modulated performances are attributed to the decreases in the refractive index modulation and average refractive index of the HPDLC grating respectively as a result of the field-induced liquid crystal reorientation. This study provides some new ideas for the improvement of DFB organic semiconductor laser to enable envisioned applications in laser displays and integrated photonic circuits.     

Selective lasing of InGaAs quantum-wire array on a V-grooved GaAssubstrate by distributed optical feedback

Distributed-feedback (DFB) lasers were fabricated by using strained InGaAs quantum-wire (QWR) arrays on V-grooved GaAs substrates as an active grating. After characterizing the luminescence from the QWRs and parasitic quantum wells (QWLs), a DFB laser cavity incorporating such a QWR array with its emission wavelength matched to the Bragg wavelength was designed and fabricated. The wavelength selectivity of the DFB cavity was found to strongly support the QWR emission, and DFB lasing from QWR gain up to 145 K has been achieved under pulsed current. The emission from the parasitic QWLs was suppressed by the DFB filtering and the loss induced by coupling to radiation modes. The DFB cavity was shown to be essential for obtaining lasing from QWRs on V-grooved substrates     

Monolithic DWDM source with precise channel spacing

We report a low-cost manufacturing approach for fabricating monolithic multi-wavelength sources for dense wavelength division multiplexing(DWDM)systems that offers high yield and eliminates crystal regrowth and selective area epitaxy steps that are essential in traditional fabrication methods.The source integrates an array of distributed feedback(DFB)lasers with a passive coupler and semiconductor optical amplifier(SOA).Ridge waveguide lasers with sampled Bragg side wall gratings have been integrated using quantum well intermixing to achieve a fully functional four-channel DWDM source with 0.8 nm wavelength spacing and residual errors<0.13 nm.The output power from the SOA is>10 mW per channel making the source suitable for use in passive optical networks(PONs).We have also investigated using multisection phase-shifted sampled gratings to both increase the effective grating coupling coefficient and precisely control the channel lasing wavelength spacing.An 8-channel DFB laser array with 100 GHz channel spacing was demonstrated using a sampled grating with twoπ-phase-shifted sections in each sampling period.The entire array was fabricated by only a single step of electron beam lithography.     

Wavelength shift enhancement in quantum-well intermixeddistributed-feedback lasers

The maximum possible shift in emission wavelength of a quantum-well (QW) intermixed distributed-feedback (DFB) laser as a function of degree of intermixing is studied. In a recent experiment, the wavelength shift of a QW intermixed DFB laser is around 13% of the bandgap blue shift. Our study indicates that if a smaller grating period is used, the wavelength shift can be increased by four times to 50% of the bandgap blue shift, because it is not necessary to change the carrier density significantly in order to maintain a modal gain above lasing threshold. The maximum tuning range is found to be 20 nm, indicating that QW intermixing can be used to fabricate multiwavelength DFB laser arrays for wavelength-division-multiplexing communication systems     

复增益耦合型取样光栅DFB激光器的设计制作与性能

A complex-coupled DFB Laser with sampled grating has been designed and fabricated. The key concepts of the approach are to utilize the +1st order reflection of the sampled grating for laser single mode operation, and use a conventional holographic exposure combined with the usual photolithography to fabricate the sampled grating. The typical threshold current of the sampled grating based DFB laser is 25mA, and the optical output is about 10mW at the injected current of 100mA. The lasing wavelength of the device is 1.5385μm, which is the +1st order wavelength of the sampled grating.     

Design and performance of a complex-coupled DFB laser with sampled grating

A complex-coupled DFB laser with sampled grating has been designed and fabricated. The method uses the + 1 st order reflection of the sampled grating for laser single-mode operation. The typical threshold current of the sampled grating based DFB laser is 25 mA, and the optical output is about 10 mW at the injected current of 100 mA. The lasing wavelength of the device is 1.5385μm, which is the +1 st order wavelength of the sampled grating.     

基于液晶/聚合物光栅选频的高效率有机半导体激光器

报道了一种基于液晶/聚合物光栅选频的高效率有机半导体激光器的制备方法。首先在一片玻璃基板上旋涂有机半导体荧光薄膜MEH-PPV作为增益介质,然后在其上通过光场中的定域光聚合制备液晶/聚合物光栅,形成分布式反馈(DFB)有机半导体激光器。激光出射阈值0.32μJ/pulse,斜率转化效率高达7.8%,呈现良好的s偏振特性。采集了激光束的光斑,轮廓清晰,呈现扇形结构。通过改变光栅周期,实现了53.4nm激光出射范围。本工作为新型有机激光器的制备提供了有益的指导和借鉴意义。     

Continuously tunable organic solid-state DFB laser utilizing molecular reorientation in molecular glasses

We report a facile way for continuously tuning the lasing wavelength of an organic thin-film distributed feedback (DFB) laser after device fabrication by varying the effective refractive index seen by the one-dimension DFB laser structure. Varying the effective refractive indices of the organic gain medium and thus the effective refractive index of a one-dimension DFB laser structure after device fabrication is made possible with reorientation of molecules in a molecular glass at elevated temperatures. Distributions of molecular orientations can be fine controlled by annealing temperatures and times, permitting continuous tuning of optical properties and lasing wavelengths. Molecular reorientation can be conducted after devices are made, thus giving one the freedom to set or tune the lasing wavelength to meet a particular purpose with a common structure.