1550 nm波段外腔窄线宽激光器增益芯片

针对外腔窄线宽激光器应用设计了一款半导体增益芯片，分析了斜率效率和增益谱特性，由于封装后增益峰红移会造成器件输出功率下降，指出设计中芯片的增益峰需偏离激光器激射波长。通过优化量子阱结构及材料应力，提高了芯片的斜率效率。为了降低芯片自身法布里-珀罗(FP)腔谐振效应，采用弯曲波导配合磁控溅射四层增透膜工艺，使芯片出光端面的有效反射率明显降低，提高了窄线宽激光器输出波长的稳定性。所设计芯片采用1%压应变量子阱材料，量子阱厚度为7.5 nm,量子阱数量为3个，芯片波导与解理面法线呈6°夹角。通过半导体流片工艺完成掩埋结芯片制作，并进行窄线宽激光器封装及测试，实现了1 550 nm波段高效稳定的窄线宽激光输出。     

大功率低阈值半导体激光器研究

针对大光腔结构往往导致阈值电流密度增大的矛盾,设计了一种具有较高势垒高度的三量子阱有源区。采用非对称宽波导结构的半导体激光器,该激光器在实现大光腔结构的同时保持阈值电流密度不增加。通过金属有机物化学气相沉积(MOCVD)生长InGaAs/AlGaAs三量子阱有源区以及3.6μm超大光腔半导体激光器的外延结构。结合后期工艺,制备了980nm脊形边发射半导体激光器。在未镀膜情况下,4mm腔长半导体激光器阈值电流为1105.5mA,垂直发散角为15.6°,注入电流为25A时的最大输出功率可达到15.9 W。测试结果表明:所设计的半导体激光器在有效地拓展光场,实现大光腔结构的同时,保证了激光器具有较低的阈值电流。     

808nm InGaAlAs垂直腔面发射激光器的结构设计

为实现垂直腔面发射半导体激光器(VCSEL)在808 nm波长的激射,对VCSEL芯片的整体结构进行了设计。基于应变量子阱的能带理论、固体模型理论、克龙尼克-潘纳模型和光学传输矩阵方法,计算了压应变InGaAlAs量子阱的带隙、带阶、量子化子能级以及分布布拉格反射镜(DBR)的反射谱,从而确定了量子阱的组分、厚度以及反射镜的对数。数值模拟的结果表明,阱宽为6 nm的In0.14Ga0.74Al0.12As/Al0.3Ga0.7As量子阱,在室温下激射波长在800 nm左右,其峰值材料增益在工作温度下达到4000 cm-1;渐变层为20 nm的Al0.9Ga0.1As/Al0.2Ga0.8As DBR,出光p面为23对时反射率为99.57%,全反射n面为39.5对时反射率为99.94%。设计的顶发射VCSEL结构通过光电集成专业软件(PICS3D)验证,得到室温下的光谱中心波长在800 nm处,证实了结构设计的正确性。     

非对称异质波导半导体激光器结构

提出了一种非对称异质波导半导体激光器外延结构,即通过优化选择材料体系和结构厚度,对器件外延层的P侧限制结构和N侧限制结构分别设计,从而降低器件的电压损耗,使其满足高输出功率以及高的电光转换效率的要求.从载流子的输运和限制等微观机制出发,对器件的主要输出特性进行了理论分析和数值模拟,并以此为根据设计和制作了一种1060 nm In Ga As/Ga As单量子阱非对称异质波导结构半导体激光器,并对器件的主要输出特性进行了测试.实验结果表明,非对称异质结构是降低器件的电压降、增大限制结构对注入载流子的限制,提高半导体激光器电光转换效率的有效措施.     

外腔面发射激光器中纳米结构的热导率

优化有源区的量子结构和改善热管理,是提高外腔面发射激光器输出功率的关键。以上两项措施都基于对激光器准确的热分析,依赖于热导率这一关键的材料参数。鉴于外腔面发射激光器中多量子阱和分布布拉格反射镜均为典型的纳米结构,考虑纳米尺度传热特性,用三种不同的解析方法,分别计算了不同厚度Ga As/Al As分布布拉格反射镜的热导率,并与已有实验报道对比,优选出更适合于计算Ga As/Al As材料系纳米结构热导率的一种方法。采用优选出的方法,对980 nm外腔面发射激光器中In Ga As/Ga As多量子阱和Ga As/Al As分布布拉格反射镜的热导率进行计算,发现分布布拉格反射镜的法向热导率只有块体材料数值的约40%,多量子阱的法向热导率则略小于块体材料数值的一半。把所得热导率数据用于增益芯片中温度上升的数值分析,结果与实验相符。     

GaAs/AlGaAs多量子阱材料差分反射光谱

介绍了一种新型的空间调制光谱技术—差分反射 ( DR)光谱技术 .利用振动光束差分反射测试系统 ,获得了 Ga As/Al Ga As多量子阱材料的 DR谱 ,初步分析了 DR信号的产生机制 .通过与材料的 PR谱及反射光谱的一阶微商谱比较分析 ,论证了 DR光谱技术用于多量子阱量子化跃迁观测的理论可行性 ,并从实验角度证明了 Ga As/Al Ga As多量子阱材料的 DR谱具有反射率谱对能量的一阶微商线型特征     

微透镜集成大功率垂直腔面发射激光器

为了改善大功率垂直腔面发射激光器(VCSEL)的模式特性,在GaAs衬底上采用限制扩散湿法刻蚀技术制作出了不同曲率半径的微透镜,与P型和N型分布式布拉格反射镜(DBR)构成复合腔结构,可以对腔内模式进行选择.有源区采用新型的发射波长为980 nm的InGaAs/GaAs应变量子阱,包括9对In0.2Ga0.8As(6 nm)/Ga0.18As.82P(8 nm)量子阱,有源区直径100μm,微透镜直径300 μm,曲率半径959.81μm,表面粗糙度13 nm.室温下,器件连续输出功率大于180 mW,阈值电流200 mA,远场发散角半角宽度分别为7.8°和8.4°,并且与没有微透镜的垂直腔而发射激光器输出特性进行了比较.     

InGaAs/GaAs多量子阱SEED面阵结构特性与设计

讨论了谐振腔中的 DBR对 In Ga As/ Ga As多量子阱 SEED面阵光反射特性的影响 .采用 In Ga As/ Ga As作为多量子阱 SEED器件的有源区 ,从而获得了 980 nm工作波长 .设计和分析了 In Ga As/ Ga As多量子阱 SEED中的一种用于倒装焊的新型谐振腔结构 .多量子阱材料是用 MOCVD系统生长 ,利用微区光反射谱、PL 谱以及 X射线双晶衍射对多量子阱材料进行了测量和分析 ,测量结果表明多量子阱材料具有良好的质量 ,证明了器件结构的设计和分析是准确的     

窄线宽1064 nm分布布拉格反射半导体激光器

1064nm分布布拉格反射(DBR)半导体激光器具有窄线宽、输出稳定的特性,在自由空间激光通信用种子光源等方面具有广阔的应用前景。设计了一种单模、窄线宽的1064nm DBR半导体激光器,利用金属有机化合物气相沉积技术生长出InGaAs应变量子阱半导体激光器材料,并制备出腔长为1200μm的脊型波导1064nm DBR半导体激光器。当注入电流为70mA时,室温下该激光器的连续输出功率可达到7mW,3dB光谱线宽为0.12nm。     

InGaAsP/GaAs单量子阱半导体激光器光学特性的研究

用改进的液相外延方法 L PE 生长了无铝的 In Ga As P/Ga As分别限制单量子阱半导体激光器 ,测量其远场分布近似为高斯分布 .用缓变波导理论分析了产生这种分布所对应的光波导结构的折射率分布模型 ,并简单解释了其生成原因 ,为改善光束质量提供了参考     

Y-Branch Surface-Etched Distributed Bragg Reflector Lasers at 850 nm for Optical Heterodyning

This letter presents a monolithically integrated dual-wavelength source at 850 nm suitable for use in optical heterodyning. The device consists of two surface-etched distributed Bragg reflector (DBR) lasers, a Y-branch coupler, and a curved waveguide outcoupler. The Y-branch coupler and curved outcoupler are fabricated with the same epitaxial material as the DBR lasers, enabling operation as a semiconductor optical amplifier. The spectral characteristics and frequency stability of the two wavelength lasers are reported.     

Thermal delocalization of carriers in semiconductor lasers (λ = 1010–1070 nm)

The temperature dependences of the emission characteristics of semiconductor lasers based on MOVPE-grown asymmetric separate-confinement heterostructures (wavelengths ?? = 1010?C1070 nm) have been studied. It was found that, in the continuous-wave mode, the main mechanism of ??saturation?? of the light-current characteristic with increasing temperature of the active region is carrier delocalization into the waveguide layer. It was experimentally demonstrated that the thermal delocalization of carriers depends on the energy depth of the quantum well (QW) in the active region. It is shown that the minimum internal optical loss at 140°C is obtained in laser structures with the largest energy depth of the QW of the active region.     

波导结构对905 nm隧道结级联半导体激光器的光束质量和功率的影响

近年来,激光雷达应用对探测距离和灵敏度提出了更高的要求。905 nm半导体激光器作为其理想光源也亟待提升峰值功率与光束质量。在这个背景下,基于非对称大光腔结构研究了不同增益区类型和波导结构对905 nm隧道结脉冲半导体激光器的光束质量和功率效率的影响。通过优化增益区类型和波导结构降低了体电阻和内损耗;增强了限制载流子泄露的能力,提高了器件在高电流下工作的峰值功率和电光效率;通过提高高阶模对基模的阈值增益比值,抑制高阶模式激射,降低了远场发散角。在此基础上,研制的800 μm腔长、200 μm条宽的四有源区半导体激光器在100 ns脉冲宽度、1 kHz重复频率的脉冲功率测试中,41.6 A的脉冲电流强度下实现了峰值功率输出177 W;垂直于PN结方向单模激射,远场发散角半高全宽为24.3°。     

大功率体光栅外腔半导体激光器的输出特性

宽条形大功率半导体激光器(LD)存在光谱温漂系数大、光谱宽度宽的缺点,为了改善宽条形大功率半导体激光器的光谱特性,采用一种体光栅(VBG)离轴外腔方法实现了宽条形大功率半导体激光器光谱特性的明显改善和高效率工作.宽条形半导体激光器的外腔结构主要包括激光器输出光束的快、慢轴准直光学透镜和离轴放置的体光栅.宽条形半导体激光器的激射条宽为100μm,当激光器工作电流为4.0 A时,外腔激光器的输出功率高达3.4 W,斜率效率为1.0 W/A,光谱宽度由自由出射条件下的2~3 nm减少为0.2 nm,峰值波长的温漂系数小于0.015 nm/℃.     

高效率GaAsP/AlGaAs张应变量子阱激光二极管

从理论上设计优化了高效率808 nm GaAsP/AlGaAs张应变量子阱激光二极管外延材料的量子阱结构和波导结构参数,并采用低压金属有机气相外延技术实验制备了外延材料.将制作的芯片解理成不同腔长,测试得到外延材料的内损耗系数和内量子效率分别为0.82 cm-1和93.6 %.把腔长为900 μm的单巴条芯片封装在热传...     

基于Bragg光栅的超高消光比SOI波导偏振器设计

波导偏振器是片上集成相干光学系统中的关键器件之一,超高消光比、低损耗、紧凑型波导偏振器的设计一直是研究的热点。基于绝缘体上硅平台的倾斜Bragg光栅被用于实现超高消光比波导偏振器结构。利用一维光子晶体能带理论分别计算TE和TM模式光的能带结构分布,选择TE模式禁带与TM导带重叠带隙设计光栅,可实现TM模式低损传输,而TE模式被Bragg光栅高效反射,从而产生超高偏振消光比。3D FDTD仿真表明:16 μm倾斜Bragg光栅波导偏振器可在中心波长1550 nm附近70 nm的带宽内,实现大于37 dB的超高消光比,器件的损耗小于0.64 dB;进一步增加光栅周期数,当长度为25 μm时,消光比可提高至46 dB。Bragg光栅倾斜角与刻蚀宽度偏差仿真表明:设计的结构加工误差容限较大,同时该结构仅需一次曝光刻蚀,工艺流程简单。     

Threshold current density reduction of strained AlInGaAs quantum-well laser

In the last decades, researchers have tried to implement novel optoelectronic devices with new semiconductor material compounds. There are few competitors in the race for more reliable, more efficient, pump sources for solid-state lasers. These diodes should operate at high power, intense brightness, and with low threshold current. The strained AlInGaAs-GaAs quantum-well (QW) laser is a promising candidate. In this study we optimized the growth parameters of strained AlInGaAs quantum wells using a model for linewidth broadening of photoluminescence, which was extended for the first time to handle quaternary alloys. This model enables us to identify the dominant contributions to the broadening. As a result of our growth parameters optimization technique, low threshold current density of simple broad-area lasers has been obtained, indicating a superior material quality. Moreover, we have studied for the first time the effect of indium and aluminum content and QW width on the threshold current density of quaternary AlInGaAs QW lasers. As a result of these studies the lowest known threshold current density for AlInGaAs on GaAs single QW broad-area laser has been achieved.     

Theory of refractive index variation in quantum well structure andrelated intersectional optical switch

Attention is focused on the deformation of electron wave functions due to an applied field in a quantum well (QW) neglecting the exciton effect. Compared to the electrooptic effect of bulk semiconductor, the theoretical refractive index variation in a QW structure due to this phenomenon is considerably larger at the wavelength corresponding to the energy gap between the first quantized energy levels in the conduction and valence bands. Since the absorption loss changes by the same mechanism, the appropriate wavelength region is estimated for larger index variation where the absorption loss is relatively smaller. The design of a related intersectional optical switch of a small size is discussed. A switch with a length of about 10 μm is achievable with an intersectional angle of more than 10° at a waveguide width of 1 μm. This optical switch is expected to be of high speed and is integrable monolithically with lasers     

Design Optimization of Reflective Polarizers for LCD Backlight Recycling

We systematically study and optimize the design of multilayer birefringent reflective polarizers for recycling the backlight of liquid crystal displays. Factors affecting the Bragg reflection are analyzed in detail, including number of layers for establishing Bragg reflection, refractive index difference, effective refractive index, and thickness ratio. Different methods for achieving broadband reflection are investigated, so that the reflective polarizer could cover the entire visible wavelengths and a large incident angle. In addition, the effects of material dispersion on the device design are analyzed.      

1310 nm GaInNAs triple quantum well laser with 13 GHz modulation bandwidth

The emission wavelength of a GaInNAs quantum well (QW) laser was adjusted to 1310 nm, the zero dispersion wavelength of optical fibre, by an appropriate choice of QW composition and thickness and N concentration in the barriers. A triple QW design was employed to enable the use of a short cavity with a small photon lifetime while having sufficient differential gain for a large modulation bandwidth. High speed, ridge waveguide lasers fabricated from high quality material grown by molecular beam epitaxy exhibited a damped modulation response with a bandwidth of 13 GHz.