基于游标原理的可调谐分布反射全光纤激光器

报道了一种新型全光纤离散可调谐分布反射(DBR)光纤激光器。光纤激光器为短腔结构,其有源区采用Er-Yb共掺单模光纤,有源光纤长度为6 cm。激光器采用两组级联光纤布拉格光栅(FBG)为反射腔镜,前腔镜各级联光纤布拉格光栅的布拉格波长间隔为1 nm,后腔镜为0.8 nm,利用游标原理,通过对前腔镜级联光纤布拉格光栅进行机械调谐,使前后腔镜各反射波长分别对准,实现了四个固定波长间隔为0.8 nm的离散调谐。这种光纤激光器具有波长调节准确,调谐速度快,成本低的优点,可用于作为多波长光纤传输系统的发射光源或系统检测光源,进一步增加级联光栅的组数可实现更大调谐范围。     

脉冲式DFB中红外量子级联激光器的气体检测系统

采用了脉冲式中红外分布反馈(DFB)量子级联激光器(QCL),其可调工作波长范围为1 248～1257 cm-1.在2.6 cm-1的可调光谱范围内,通过每个温度下的硫化氢光谱来描述QCL系统的温度调谐特性.利用所采集的标准具信号来校准频率,解析信号特性可得出系统的分辨率.采用直接光谱吸收技术,并结合系统中多反腔所提供...     

高性能InAs/GaAs量子点外腔激光器

为了获得高性能的量子点外腔激光器(ECL),利用InAs/GaAs量子点Fabry-Perot(FP)腔激光器研制了光栅外腔可调谐ECL。对InAs/GaAs量子点ECL进行了一系列的性能测试,主要包括单模稳定性测试、单模调谐范围测试、阈值电流密度测试、无跳模连续调谐测试和输出功率测试。在室温条件下获得了24.6nm的连续调谐范围,覆盖波长从999.2nm到1 023.8nm,并且实现了波长无跳模连续调谐。在调谐范围内最低阈值电流密度为1 525A/cm2,而且在中心波长处获得的单模输出功率为15mW,单模边模抑制比(SMSR)高达35dB。研究结果表明,通过构建光栅外腔可以实现高性能的InAs/GaAs量子点ECL。     

基于光栅光阀可调谐半导体激光器外腔结构的设计研究

目的:提出利用光栅光阀(GLV)来精密调节光栅外腔半导体激光器输出波束的新方法。方法:这种基于光栅光阀的可调谐外腔半导体激光器的结构使光栅光阀与闪耀光栅形成了共焦结构,便于使被选择的波束可以原路返回,经过在谐振腔中振荡,最后输出。结果:这种基于光栅光阀结构的可调谐外腔半导体激光器可以任意控制输出或者被过滤掉的相应波束的数量。结论:利用光栅光阀的特性,这种可调谐外腔半导体激光器能有效地实现激光输出波束的精密调谐,同时也降低了调谐的机械难度。     

窄线宽半导体激光器件

分布反馈半导体激光器的线宽一般较大，难以满足光纤传感等领域的要求。根据C.H. Henry于1982年提出的半导体激光器的线宽理论，通过适当设计DFB半导体激光器的腔长、耦合系数、微分增益、光限制因子，能有效地减小激光器的线宽。同时，空间烧孔现象也可限制DFB半导体激光器的线宽，为此需要合理设计光栅结构。在此基础上，DFB激光器的线宽能达到几十千赫兹的量级。此外，采用DBR结构或者外腔结构，也可以获得相当窄的线宽。     

基于分布反馈激光器布里渊散射的高精度光谱测量

实现了一种基于光纤中受激布里渊散射(SBS)效应 的高分辨率光谱测量技术。使用连续可调谐分布反馈(DFB) 激光器作为泵浦光,与待测信号光在单模光纤(SMF)中发生受激布里渊放大相互作用,由此 实现对待测光的高分 辨率光谱测量与分析。DFB激光器的波长扫描通过高精度温度调谐来实现。与相关报道 中使用的外腔 可调谐激光器对比,DFB激光器具有体积小、成本低的优势。同时在波长扫描过程中,对DFB 激光器的输出光进行自 拍频处理获得其实时扫描速率,以此校正激光器的实时扫描波长,提高测量准确度。实验 初步验证了本文高分辨率光谱测量技术的可行性,并获得了0.24pm 的光谱分辨率。     

用选择混合InGaAsP-InGaAsP量子阱技术研制的两段波长可调谐分布布拉格反射激光器

采用选择混合InGaAsP-InGaAsP量子阱技术,研制出单脊波导结构的两段可调谐分布布拉格反射(DBR)激光器.激光器的阈值电流为51mA,可调谐范围为4.6nm,边模抑制比(SMSR)为40dB.     

用选择混合InGaAsP-InGaAsP量子阱技术研制的两段波长可调谐分布布拉格反射激光器

采用选择混合InGaAsP InGaAsP量子阱技术,研制出单脊波导结构的两段可调谐分布布拉格反射(DBR)激光器.激光器的阈值电流为51mA ,可调谐范围为4 6nm ,边模抑制比(SMSR)为40dB .     

利用传输矩阵法分析取样光栅DBR半导体激光器

取样光栅DBR(SGDBR)激光器是目前光通讯中最有应用前景的可调谐激光器之一。利用传输矩阵法模拟了取样光栅DBR半导体激光器的光谱特性。计算中,把取样光栅DBR半导体激光器的增益区、位相区和取样光栅DBR看成基本单元。而每一个基本单元都可以看作一个普通的双端口器件。其传输特性用一个2×2复矩阵表示。在阈值以下,对于有源区和取样光栅DBR的不同注入电流,发射光谱显示不同的输出特征。当有源区的注入电流为9.5 mA时,主模开始在1.553μm附近形成。当取样光栅DBR有注入电流时,主模形成的位置发生了变化,表现出可调谐的性质。同时,明显出现主模的有源区的注入电流发生变化。这种方法也反映了激光器的阈值条件。阈值电流为10 mA。     

用选择混合InGaAsP-InGaAsP量子阱技术研制的两段波长可调谐分布布拉格反射激光器

采用选择混合InGaAsP InGaAsP量子阱技术 ,研制出单脊波导结构的两段可调谐分布布拉格反射 (DBR)激光器 .激光器的阈值电流为 51mA ,可调谐范围为 4 6nm ,边模抑制比 (SMSR)为 40dB .     

A Michelson interferometer with balanced detection for thecharacterization of modulation and noise properties of semiconductorlasers

A Michelson interferometer with balanced detection, built to study semiconductor lasers, is analyzed. The quantum noise due to vacuum fluctuations, coupling losses, detector quantum efficiency, and spatial mode mismatches are included in the analysis. The limits for frequency noise detection and the sensitivity of the interferometer are examined. It is observed that under ordinary measurement conditions the frequency noise can only be measured up to slightly above the cavity bandwidth of the laser. Comprehensive measurement procedures are proposed, and experimental results showing the frequency modulation response, measured from 10 kHz to 8 GHz, of a three-section distributed feedback (DFB) laser and the frequency noise spectra, measured from 30 MHz to 8 GHz, of a two-section distributed Bragg reflector (DBR) laser are presented. These results reveal new cavity detuning effects in the noise characteristics of tunable DBR lasers     

Analysis of the phase-amplitude coupling factor and spectrallinewidth of distributed feedback and composite-cavity semiconductorlasers

A Green's function approach to the analysis of semiconductor lasers is formulated in a form suitable for complex cavity structures. Both the spontaneous emission rate and the effective phase-amplitude coupling factor can be accurately evaluated. For distributed-feedback (DFB) lasers, the spontaneous emission rate is strongly dependent on both the facet reflectivities and the grating coupling coefficients. The effective phase-amplitude coupling factor depends on the wavelength detuning from the gain maximum. The calculated linewidth of DFB lasers differs considerably from previous calculated results and gives better agreement with experimental results. For composite-cavity lasers, the frequency dependence of the equivalent reflectivity has a strong impact on the phase-amplitude coupling factor and the spontaneous emission rate. Distributed Bragg reflector (DBR) lasers are investigated as an example of a composite-cavity structure     

Analysis of surface-emitting λ/4-shifted DFB lasers with adistributed Bragg reflector

Threshold current density and differential quantum efficiency are analyzed for a surface emitting (SE) λ/4-shifted distributed feedback (DFB) laser consisting of alternating active and passive layers with a distributed Bragg reflector (DBR). It is shown that the threshold current density can be reduced by using the DFB action induced by alternating active and passive layers in the active region of the SE DFB laser structure, as compared to SE DBR lasers with a homogeneous active region. It is also shown that the differential quantum efficiency of the DFB laser with a DBR can be higher than that of conventional DBR lasers without increasing the threshold current density     

Distributed feedback quantum cascade lasers operating in continuous-wave mode at λ≈7.6μm

正Distributed feedback(DFB) quantum cascade lasers(QCLs) in continuous-wave(CW) mode emitting atλ≈7.6μm are presented.Holographic lithography was used to fabricate the first-order distributed feedback grating. For a high-reflectivity-coated QCL with 14.5-μm-wide and 3-mm-long cavity,CW output powers of 300 mW at 85 K and still 10 mW at 270 K are obtained.Single-mode emission with a side-mode suppression ratio(SMSR) of about 30 dB and a wide tuning range of ~300 nm in the temperature range from 85 to 280 K is observed.     

DFB Quantum Cascade Laser Arrays

DFB quantum cascade laser (DFB-QCL) arrays operating between 8.7 and 9.4 $mu$m are investigated for their performance characteristics—single-mode selection of the DFB grating, and variability in threshold, slope efficiency, and output power of different lasers in the array. Single-mode selection refers to the ability to choose a desired mode/frequency of laser emission with a DFB grating. We apply a theoretical framework developed for general DFB gratings to analyze DFB-QCL arrays. We calculate how the performance characteristics of DFB-QCLs are affected by the coupling strength $kappa L$ of the grating, and the relative position of the mirror facets at the ends of the laser cavity with respect to the grating. We discuss how single-mode selection can be improved by design. Several DFB-QCL arrays are fabricated and their performance examined. We achieve desired improvements in single-mode selection, and we observe the predicted variability in the threshold, slope efficiency, and output power of the DFB-QCLs. As a demonstration of potential applications, the DFB-QCL arrays are used to perform infrared absorption spectroscopy with fluids.      

DBR module with 20-mW constant coupled output power, over 16 nm(40×50-GHz spaced channels)

To replace DFB lasers in wavelength-division-multiplexing (WDM) systems, tunable lasers should provide the same output power (20 mW) and remain simple devices. We propose a two-section DBR laser with optimized design. The required settings to reach all the achievable ITU wavelengths with constant output power are simply derived from very few initial characterizations. We obtain a record 20-mW coupled output power, constant over 16 nm (=40 channels 50-GHz spaced). For the first time, power performances comparable with DFB lasers are obtained; DBR lasers are now competitive candidates for an integration in WDM systems     

Evaluation of an automatic method to extract the grating couplingcoefficient in different types of fabricated DFB lasers

Distributed feedback (DFB) laser parameters such as grating coupling coefficient, effective indices, facet reflectances, and the phases of facet reflectances have been determined using a method based on least-square fitting of theoretical spectra to measured, subthreshold DFB laser emission spectra. The only inputs needed are geometrical parameters such as length, grating period, and internal grating phase shifts. A larger number of devices have been successfully characterized, and consistent results have been obtained in both 1.3-μm multi-quantum-well (MQW) DFB lasers with both facets as-cleaved, and in 1.55-μm MQW DFB lasers with no, one, or two facets as-cleaved     

DBR单纵模光纤激光器波长温度调谐

报道了采用DBR方式,利用8 mm的高浓度掺Yb3+单模光纤,实现了波长为1 064 nm的单纵模调谐激光稳定输出的实验结果。该DBR谐振腔有效腔长为16 mm,输出最大功率为7.4 mW,通过半导体制冷器温控改变谐振腔的温度,实现了0.824 nm的单纵模无跳模调谐。采用光纤外差法,并利用低损耗环形器和光纤反射镜倍增延迟线长度提升测量精度的方式,测量得到激光最大线宽为4.4 kHz。单纵模激光的弛豫震荡峰位于900 kHz处,其相对强度噪声为-110 dB/Hz,当频率大于1.5 MHz时相对强度噪声为-145 dB/Hz。