可调谐DBR激光器、电吸收调制DFB激光器用高质量InGaAsP-MQW材料的选择区域生长

本文报道了采用选择区域生长（Ｓｅｌｅｃｔｉｖｅ ａｒｅａ ｇｒｏｗｔｈ, ＳＡＧ）方法,在 ＳｉＯ２作掩膜的 ＩｎＰ衬底上选择生长出高质量的 ＩｎＧａＡｓＰ－ＭＱＷ,并成功地制作出波长调谐范围达 ６．５ ｎｍ的可调谐 ＤＢＲ激光器和性能可靠的电吸收调制ＤＦＢ激光器．ＳＡＧ成为实现光子集成器件的有效途径,得到广泛的研究,并已实现了ＤＦＢ激光器与电吸收调制器的单片集成 （ｅｌｅｃｔｒｏａｂｓｏｒｐｔｉｏｎ ｍｏｄｕｌａｔｅｄ ＤＦＢ Ｌａｓｅｒ, ＥＭＬ）．我们在国内率先开展这方面的研究,并取得重大的突破． 采用 …     

利用全光纤自外差系统研究光纤光栅半导体激光器的线宽

以带光纤尾纤引出式微体声光移频器（ＡＯＦＳ）为基础,用全光纤结构的延迟自外差激光器线宽测量系统（分辨率为５０ｋＨｚ）,其中声光移频器插入损耗仅为２．９ｄＢ,大大提高了信噪比。采用该系统对窄线宽１．３μｍ光纤光栅半导体激光器（ＦＢＧ－ＬＤ）进行了测量,测得激光器线宽的典型值为１．５ＭＨｚ,同时分析了测量系统近端反射光对线宽测量精度的影响以及ＦＢＧ－ＬＧ的线宽压窄特性,最后验证了ＦＢＧ－ＬＤ 输出线宽     

大信号直接调制半导体激光器的谐波非线性失真特性研究

本文对微波副载波光纤传输中最关心的大信号调制半导体激光器的谐波非线性进行了理论与实验研究。在ＬＤ速率方程的基础上，建立了一个适合计算谐波失真特性的分析模型。同时，对这一个国产１．５５μｍＩｎＧａＡｓＰＤＣ－ＰＢＨ－ＤＦＢ－ＬＤ的二次与三次谐波特性进行了测量，结果与理论计算值一致。     

分布反馈式半导体激光器耦合系数计算与垂向结构设计

本文推导出增益耦合型分布反馈式（ＤＦＢ）半导体激光器ＴＥ、ＴＭ模耦合系数Ｋ的计算公式．分析了ＤＦＢ激光器的横模，讨论了ｋ与ＤＦＢ激光器横模、光栅级数、占空比及吸收光栅层厚的关系．最后得出含吸收光栅的ＧａＡｌＡｓ／ＧａＡｓ增益耦合型ＤＦＢ激光器在采用三级光栅时的优化设计结果为：占空比０．１６，吸收层厚５０ｕｍ．     

DFB激光器静态特性的模拟分析

本文提出一个新的对分布反馈（ＤＢＦ）半导体激光器进行数值分析的模型,并对ＤＦＢ激光器在阈值以上时的稳定性进行了分析,该模型考虑了空间烧孔效应和非线性增益效应,提出用向量法解决ＤＦＢ激光器矩阵模型的数值方法,与牛顿－拉斐森（ＮＲ）法相比,向量法避免了复杂的自洽运算,节省了运算时间。文章还分析了非激光射模型存在时ＤＦＢ的单模稳定性问题。本文提出的数值模型适用于各种结构的ＤＦＢ激光器的特性分析。     

GaAlAs／GaAs欧量子阱增益耦合型DFB激光器电吸收型调制器单片光子…

我们在国际上率先提出将增益耦合分布反馈式（ＧＣ－ＤＦＢ）半导体激光器作为激光器／调制器单片集成器件的光源，为了简化制作工艺，进一步提出激光器的有源层与调制器波动共用同一组分和同一结构，本理论上分析了新型器件的可行性，优化设计了器件结构，在此基础上，采用金属有机化合物化学汽相外延技术（ＭＯＣＶＤ）在国际上首次研制成功了该种增益耦合型ＤＦＢ激光器／电吸收型调制器单片光子集成器件，器件电流为３５ｍＡ。     

提高国产激光器组件直接调制速率与PIN－FET组件频响带宽的新技术

本文对如何提高国产１．５５μｍＩｎＧｒａＡｓｐＤＦＢ－ＬＤ组件直接高速调制速率以及国产ＰＩＮ－ＦＥＴ组件的频响带宽进行了理论与实验研究。在实验测量的基础上建立了国产ＬＤ组件小信号等效电路模型，对其调制响应速率的主要限制因素进行了分析，研制了高速ＤＦＢ－ＬＤ组件，将其调制速率提高到３．２ＧＨｚ。同时，在对谐振式ＰＩＮ－ＦＥＴ光接收机进行噪声分析的基础上，采用微波混合集成工艺研制了一个串联谐振式ＰＩＮ－ＦＥＴ光接收组件，有效地提高了ＰＩＮ－ＦＥＴ的频响带宽。     

LD泵浦的内腔倍频激光器单频运转的理论研究

给出了激光二极管（ＬＤ）端面泵浦的内腔倍频激光器单频运转时的最大泵浦功率与腔参数和材料参数间的简单函数关系，并对ＬＤ泵浦的ＮｄＹＶＯ４及ＮｄＹＡＧ内腔倍频激光器的单频运转进行了详细的分析。     

可调谐光纤激光器产生11nm调谐范围

根据１９９９年激光和电光会议技术报告,美国Ｅ－ＴＥＫ动力公司的研究人员设计出一种用于可重新配置的高速密集波分复用网络的可调谐高功率光纤激光器。据Ｅ－ＴＥＸ创始人Ｊ．Ｊ．Ｐａｎ称：这种微型的发射机设计可提供１１ｕｒｎ的调谐范围和６２ｍｗ的输出功率,并能维持低于１６５ｄＢ／Ｈｚ的相对强度噪声和一３２ｄＢｍ的测量系统强度。该器件的核心是一个由高反射率光纤Ｂｒａｇｇ光栅、光学耦合光纤Ｂｒａｇｇ光栅（ＦＢＧ）和夹在它们之间的分布反馈（ＤＢＦ）光纤激光器构成的交互式光纤激光器（ＩＦＬ）。然后ＩＦＬ与带有一个…     

光网络与光子集成的发展(下)

光网络体系中的有源光子集成 高速响应、低啁啾、单稳频集成光子源 半导体分布反馈（ＤＦＢ）激光器作为光通信的光子源器件已占据不可替代的重要地位,然而ＤＷＤＭ光网络对光子源却提出更高的要求。直接调制ＤＦＢ激光器受到固有张弛振荡效应的限制,响应速率难以越过５Ｇｂ／ｓ,同时在高速率下,频移啁啾效应已比较严重,因此必须采用外调制技术,从光网络体系考虑,调制器宜结构简单并能与ＤＦＢ激光器实现单片集成。现在的激光器均已采用量子阱（ＭＱＷ）结构,因此人们致力于发展基于ＭＱＷ中量子限制Ｓｔａｒｋ效应（ＱＣＳＥ）的电…     

A two-step laterally tapered 1.55-/spl mu/m SSC DFB laser fabricated by using a nonselective grating process

We demonstrate a two-step laterally tapered 1.55-/spl mu/m spot size converter distributed feedback laser diode (SSC DFB LD) having a planar buried heterostructure-type active waveguide and a ridge-type passive waveguide fabricated by using a nonselective grating process. Unlike conventional SSC DFB LDs, where a selective grating is employed, this SSC DFB LD employed a nonselective grating over the entire device region in order to make its fabrication much simpler than that of the conventional SSC DFB LDs. The two-step laterally tapered SSC is effective in removing an unwanted wavelength peak originating from the SSC section having a multiquantum well and a grating under it. The fabricated SSC DFB LD operates at 1.553-/spl mu/m wavelength and shows a far field pattern in horizontal and vertical directions of 13.4/spl deg/ and 19.5/spl deg/, respectively.     

Analysis and simulation of gain-coupled distributed feedbacksemiconductor lasers

In this paper, a general computer code is presented for the analysis of gain coupled (GC)-DFB structures. The code allows to consider and to compare different GC-DFB structures realized with a gain grating (GG) or an absorption grating (AG) or a second order index grating (SOG). The formulation for index grating laser has been extended considering two rate equations for AG lasers. Linewidth, side-mode suppression ratio, FM and AM response and other laser characteristics are evaluated and discussed for different structures     

低掺杂铒纤上分布反馈布拉格光纤激光器的制作

采用准分子激光器成功地在低掺杂普通铒纤上制作出5 cm的光纤光栅分布反馈布拉格(DFB)激光器,铒纤的峰值吸收率为5 dB/m,在100 mW,980 nm抽运光条件下,光纤激光器的输出功率为50μW,边模抑制比为50 dB。使用耦合模理论分析了一段5 cm带相移的分布反馈布拉格光纤激光器输出光强同腔内损耗及相移量的关系,计算结果表明,光纤腔内的损耗对激光器的输出具有非常重要的影响,大的损耗对应获得最大功率的光栅耦合强度相应减小,因此,在低掺杂铒纤上制作分布反馈布拉格激光器必须正确估计光纤激光器的腔内损耗,选择合适的光栅耦合强度,可以获得较大的输出功率。     

Improvement of linewidth enhancement factor in 1.55-μmmultiple-quantum-well laser diodes

The improvement of the linewidth enhancement factor in complex-coupled laser diode (CC-LD), or loss-coupled, was confirmed by measuring the spontaneous emission spectra below threshold from the sidewall of laser diodes. In addition, the serial resistance of the device was measured. The linewidth enhancement factor is improved by the presence of a light absorbing InGaAs grating for loss coupled distributed-feedback (DFB) laser diode (LD). We report the comparison of the linewidth enhancement factors of Fabry-Perot (FP) LD, conventional DFB-LD, and loss coupled DFB-LDs     

On the validity of estimating axial nonuniformity of photon density from output power ratio in uniform grating DFB lasers

The validity of the method of estimating nonuniformity in axial photon distribution from front-to-rear output power ratio has been studied by an effective index transfer matrix method. The correlation between the front-to-rear output power ratio and the maximum-to-minimum photon density ratio is shown to be good over the whole useful range of the grating coupling coefficient in uniform grating DFB laser with low-reflection/high-reflection facets, and an accurate estimation is possible. However, the correlation becomes poor as the reflectivity of the high-reflection facet decreases and the coupling coefficient increases, resulting in poor estimation.     

Two-step laterally tapered spot-size converter 1.55-/spl mu/m DFB laser diode having a high slope efficiency

We demonstrate a two-step lateral tapered 1.55-/spl mu/m spot-size converter distributed feedback laser diode (SSC DFB LD) having slope efficiencies as high as 0.457 and 0.319 mW/mA measured at 25 /spl deg/C and 85 /spl deg/C, respectively. The SSC DFB LD fabricated by using a nonselective grating process has a double core waveguide structure including a planar buried heterostructure type active waveguide and a ridge type passive waveguide. The fabricated SSC DFB LD operates at 1.553-/spl mu/m wavelength and shows a far-field pattern in horizontal and vertical directions of 7.3/spl deg/ and 11.6/spl deg/, respectively.     

Optimization of grating duty factor in gain-coupled DFB lasers withabsorptive grating-analysis and fabrication

Grating duty factor strongly affects the performance of gain-coupled (GC) distributed feedback (DFB) laser diodes with an absorptive grating. Through numerical analysis the authors have found an optimum value in the duty factor for their low threshold operation. The minimum threshold gain achievable at this optimum duty factor is found to be almost independent of the order of the grating. According to this prediction, the authors have fabricated GaAlAs/GaAs GC DFB lasers with a third-order absorptive grating where the grating duty factor has been made close to the theoretical optimum value. In 200-μm-long devices with both facets as-cleaved, low CW threshold current of 25 mA, external efficiency of 0.5 mW/mA, and SMSR as high as 45 dB have been obtained, which is qualitatively consistent with the analysis. High yield of single mode oscillation seems to be the result of the gain coupling     

Gain-coupled distributed feedback semiconductor lasers with anabsorptive conduction-type inverted grating

A gain-coupled (GC) distributed feedback (DFB) semiconductor laser with an absorptive conduction-type-inverted grating is proposed. Devices based on GaAlAs/GaAs materials are fabricated using two-step OMVPE. By inverting the conduction type of the absorptive region, threshold current is lowered by 10 mA, which is to compensate for the threshold increase due to extra absorption. In addition, nonlinear output property associated with the saturable nature of the absorption is eliminated. An ultralow chirping capability under gain switching high speed modulation and the narrow linewidth nature of this laser are experimentally studied     

Effects of radiation loss on the performance of second-order DFBsemiconductor lasers

The effects of radiation loss on the performance of second-order distributed-feedback (DFB) semiconductor lasers with a symmetrical grating are analyzed systematically. The threshold gains of the two lowest modes, the differential quantum efficiency, and the spectral linewidth are calculated as a function of the complex coupling coefficient. The comparison is also made between a conventional DFB and a quarter-wave phase-shifted DFB laser. It is shown that the effects of radiation loss are different in these two laser types. In addition, a simple approximate expression for threshold gain is derived. By way of example, a DFB laser with a rectangular grating is analyzed. It is shown that the performance of a second-order DFB laser is not sensitive to the grating pitch over a fairly wide range, provided that it is close to the pitch which gives the maximum coupling coefficient     

基于1665 nm激光器测量甲烷气体浓度的研究

介绍了一种以1665 nm分布反馈(DFB)激光器为光源,使用双光路差分吸收光谱技术(DAS)测量甲烷浓度的检测系统。双光路差分吸收光谱技术能有效抑制由于光源光强变化、探测器零点漂移等因素所引起的测量的不准确。文中对这种检测方法进行了理论和实验分析,系统的最小探测浓度为100×10-6,响应时间约为14 s。