Room temperature continuous wave low threshold current 850 nm ion implanted vertical cavity surface emitting laser using tungsten wires as mask

Vertical cavity surface emitting laser (VCSEL) emitting at 850 nm plays more important role in local fiber communication. Most of the VCSEL products emitting at 850 nm are fabricated by ion implanting. Their threshold current is about 4–6 mA. Using tungsten wires as mask, we developed the parameter of implantation and fabricated 850 nm VCSEL under room temperature CW (continuous wave) operation. The threshold current was 1.4 mA, which was lower than that of most similar devices reported before. The resistance of the device was 206 Ω. The light power was 0.92 mW at 6.74 mA under room temperature CW operation, while the light power did not achieve obvious saturation. The most remarkable advantage was that the fabrication method was simple and the optimization was available to implanting parameter.     

V型槽衬底内条形大光腔可见光半导体激光器

采用一种新的液相外延工艺，研制出具有大光腔结构的Ｖ型槽衬底内条形可见光发射半导体激光器，其光谱波长为７７９－７８４ｎｍ，室温连续工作阈值电流为６０ｍＡ，具有２倍阈值的基模工作时，线性输出光功率可达８ｍＷ，４ｍＷ下工作寿命已超过３０００小时。     

AlGaInP visible quantum well lasers for information technology

650 nm-range AlGaInP multi-quantum well (MQW) laser diodes grown by low pressure metal organic chemical vapor deposition (LP-MOCVD) have been studied and the results are presented in this paper. Threshold current density of broad area contact laser diodes can be as low as 350 A/cm². Laser diodes with buried-ridge strip waveguide structures were made, threshold currents and differential efficiencies are (22–40) mA and (0.2–0.7) mW/mA, respectively. Typical output power for the laser diodes is 5 mW, maximum output power of 15 mW has been obtained. Their operation temperature can be up to 90°C under power of 5 mW. After operating under 90°C and 5 mW for 72 hrs, the average increments for the threshold currents of the lasers at 25°C and the operation currents at 5 mW (at 25°C) are (2–3) mA and (3–5) mA, respectively. Reliability tests showed that no obvious degradation was observed after 1400 hours of CW operation under 50°C and 2.5 mW. Presented at the 1st Czech-Chinese Workshop “Advanced Materials for Optoelectronics”, Prague, Czech Republic, June 13–17, 1998.     

高温稳定25 Gbit/s 850 nm垂直腔面发射激光器

通过在N型分布布拉格反射镜(DBR)中采用高热导率AlAs材料,且增加AlAs层所占的厚度比例,在保持DBR反射率基本不变的情况下,大幅度增加了N型DBR的热导率,提高了器件高温工作性能。制作了氧化限制型顶发射VCSEL器件,不同温度条件下的直流测试结果表明:25℃时热反转功率超过8 mW;85℃时热反转电流为11 mA,功率达5 mW,表现出较好的高温工作特性。远场发散角小于17°。0～70℃的温度条件下眼图都较清晰,表明器件满足高温25 Gbit/s工作要求。     

Metal-clad ridge waveguide structure InGaP/InGaAIP visible laser diodes

InGaP/InGaAIP visible-light laser diodes with a metal-clad ridge waveguide structure have been fabricated. Compressively strained SCH-MQW structures were grown by low-pressure MOCVD and the lasing wavelength was 690 nm. The threshold current was 28 mA at 25°C for a 400 m cavity and 5 m stripe width. CW operation was obtained as the cleaved device by employing thick gold layer as a heat spreader. The light-output power versus CW current was linear up to a maximum light output power of 38 mW. Stable operation of the fundamental transverse optical mode was maintained up to 30 mW. These results show that this metal-clad ridge waveguide structure provides sufficient current confinement even under high light output power operation.     

高功率InGaAs量子阱垂直腔面发射激光器的研制

采用AlAs氧化物限制工艺实验制备了衬底出光的高功率大出光窗口（直径为300 μm）InGaAs/GaAs量子阱垂直腔面发射半导体激光器,实现了器件室温准连续工作（脉冲宽度为50 μs,重复频率为1000 Hz）,并对器件的伏安特性、光输出特性、发射光谱,以及器件的远场发射特性等进行了实验测试.器件阈值电流为460mA,器件的最大光输出功率为100mW,发射波长为978.6nm, 光谱半功率全宽度为1.0 nm,远场发散角小于10°,垂直方向的发散角θ_⊥为8°,水平方向的发散角θ_∥为9°,基本为圆形对称光束.     

High-performance,continuous-wave quantum-cascade lasers operating up to 85°C at <Emphasis Type="Italic">λ</Emphasis>∼8.8 μm

High-temperature, high-power, and continuous-wave (CW) operation of quantum-cascade lasers with 35 active/injector stages at λ∼8.85 μm above room temperature is achieved without using a buried heterostructure. At this long wavelength, the use of a wider ridge waveguide in an epilayer-down bonding scheme leads to a superior performance of the laser. For a high-reflectivity-coated 21 μm×3 mm laser, the output power of 237 mW and the threshold current density of 1.44 kA/cm² at 298 K under CW mode are obtained with a maximum wall-plug efficiency of 1.7%. Further improvements were observed by using a 4-mm-long cavity. The device exhibits 294 mW of output power at 298 K and it operates at a high temperature, even up to 358 K (85°C). The full widths at half-maximum of the laser beam in CW operation for the parallel and the perpendicular far-field patterns are 25°and 63°, respectively.     

1.3 μm planar buried heterostructure distributed feedback lasers grown by four-step MOVPE

Data are presented on InGaAsP/InP planar buried heterostructure (PBH) distributed feedback (DFB) lasers operating at 1.3 m. A four-step MOVPE process and holographic lithography are employed to fabricate these lasers. The CW laser threshold and the slope efficiency from these lasers are 9 mA and 0.23 mW mA^-1 per facet at room temperature. Single-longitudinal-mode operation with side-mode suppression of more than 35 dB is obtained at 5 mW.     

(Tm,Ho):YLF微片激光器的实验研究

报道了一台连续792 nm Ti:Al2O3激光器纵向抽运的(Tm,Ho):YLF微片激光器.在室温条件下,当抽运功率为680 mW时,激光器在2.06 μm波长的输出功率达到90 mW.激光器阈值为380 mW,光光转换效率为13%,斜率效率为26%.     

2.0 μm 波段Sb基多量子阱材料的制备

采用分子束外延外延生长技术,优化InGaAsSb/AlGaAsSb多量子阱点材料的生长速率、生长温度和束流比等生长参数,获得了高质量的多量子阱材料。室温光荧光谱表明,材料的发光波长为2.0 m左右。该结果表明,通过优化生长条件和结构参数制备的量子阱材料,可以获得良好的结构质量和光学特性。所制备的器件室温条件下输出功率22 mW,阈值电流300 mA。     

低阈值852nm半导体激光器的温度特性

通过金属有机化学气相淀积(MOCVD)和半导体后工艺技术制备了852 nm半导体激光器,它在室温下的阈值电流为57.5 m A,输出的光谱线宽小于1 nm。测试分析了激光器的输出光功率、阈值电流、电压、输出中心波长随温度的变化。测试结果表明,当温度变化范围为293~328 K时,阈值电流的变化速率为0.447m A/K,特征温度T0为142.25 K,输出的光功率变化率为0.63 m W/K。通过计算求得理想因子n为2.11,激光器热阻为77.7 K/W,中心波长漂移速率是0.249 29 nm/K,实验得出的中心波长漂移速率与理论计算结果相符。实验结果表明,该半导体器件在293~303 K的温度范围内,各特性参数能够保持相对良好的状态。器件如果工作在高温环境,需要添加控温设备以保证器件在良好状态下运行。     

High power AlGaInP laser diodes with zinc-diffused window mirror structure

The technology of zinc-diffusion to improve catastrophic optical damage (COD) threshold of compressively strained GaInP/A1GaInP quantum well laser diodes has been introduced. After zinc-diffusion, about 20-μm-long region at each facet of laser diode has been formed to serve as the window of the lasing light. As a result, the COD threshold has been significantly improved due to the enlargement of bandgap by the zinc-diffusion induced quantum well intermixing, compared with that of the conventional non-window structure. 40-mW continuous wave output power with the fundamental transverse mode has been realized under room temperature for the 3.5-μm-wide ridge waveguide diode. The operation current is 84 mA and the slope efficiency is 0.74 W/A at 40 mW. The lasing wavelength is 656 nm.     

1.06 μm InGaAs/InGaAsP量子阱半导体激光器的温度特性

研究了1.06 μm InGaAs/InGaAsP量子阱半导体激光器厘米bar模块的温度特性,测试分析了该模块的输出光功率、阈值电流、转换效率和光谱随注入电流及管芯温度变化的特性。结果表明,器件在15~55 ℃范围内所测的输出光功率由40.7 W降低到29.4 W,阈值电流由9.29 A升高到17.24 A,转换效率由54.22%降低到37.55%,光谱漂移为0.37 nm/℃,特征温度为68.6 K。实验结果表明,为保持器件性能的稳定,在实际应用过程中应该使器件的温度控制在15~25 ℃范围内。     

2.5THz量子级联激光器的研制

基于束缚态到连续态跃迁有源区能带结构,实现了2.5THz量子级联激光器的连续波工作。激光器的输出频率随电流可在2.45~2.47THz之间可调,在连续波工作模式下的最高输出功率大于6.0mW,最高连续波工作温度为60K,阈值电流密度为120A/cm2,经Si透镜整形后的输出光斑为高斯分布。     

Long wavelength strain-engineered InAs multi-layer stacks quantum dots laser diode on GaAs substrate

The growth of GaAs based 1.5 ??m multi-layer stacked InAs quantum dots (QDs) has been investigated by solid-source molecular beam epitaxy (SSMBE), which was very important devices for transmission window. Owing to a strong electronic coupling between the QDs layers and the quantum wells (QWs), and antimony (Sb) introduced by for long-wavelength semiconductor lasers were obtained. The device structure for QDs laser diodes (LDs) with a cavity length of 1000 ??m and stripe width of 100 ??m as well as the device fabrication results will also be presented. The output performance was achieved with continuous wave (CW) operation, the measurement were from 20 to 60°C with a temperature step of 10°C. The threshold current density was 168 A/cm², and the CW operating up to 20 mW at room temperature (RT) was achieved.     

Fabrication and low threshold current density CW operation of GaInAsP/InP multiple-reflector microcavity laser

We report CW operation of a GaInAsP/InP multiple-reflector microcavity (MRMC) laser operated at fairly low threshold current density. The threshold current density with broad contact (stripe widthW=240 m, cavity lengthL=60 m) under pulsed operation was 180 A cm^–2 (l _th=20 mA), and was 230 A cm^–2 under CW operation at room temperature operating at 1.52 m wavelength.     

Beam profile characteristics of InGaAs sub-monolayer quantum-dot photonic-crystal VCSELs

An InGaAs sub-monolayer (SML) quantum dot photonic crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fiber-optic applications is first time demonstrated. The active region of the device contains 3 InGaAs SML QD layers. Each of the InGaAs SML QD layer is formed by alternate deposition of InAs (<1 ML) and GaAs. Single fundamental mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. Side-mode suppression ratio (SMSR) larger than 35 dB has been demonstrated over entire current operation range. The beam profile study of the PhC-VCSEL indicates that the laser beam is well confined by the photonic crystal structure of the device. The divergence angle of the devices remains almost unchanged with increasing current.     

Continuous‐wave vertically emitting photonic crystal terahertz laser

Compact semiconductor light sources with high performance continuous‐wave (CW) and single mode operation are highly demanded for many applications in the terahertz (THz) frequency range. Distributed feedback (DFB) and photonic crystal (PhC) quantum cascade (QC) lasers are amongst the leading candidates in this field. Absorbing boundary condition is a commonly used method to control the optical performance of a laser in double‐metal confinement. However, this approach increases the total loss in the device and results in a large threshold current density, limiting the CW maximum output power and operating temperature. In this letter, a robust surface emitting continuous‐wave terahertz QC laser is realized in a two‐dimensional PhC structure by a second order Bragg grating extractor that simultaneously provides the boundary condition necessary for mode selection. This results in a 3.12 THz single mode CW operation with a 3 mW output power and a maximum operation temperature (T_max) of 100 K. Also, a highly collimated far‐field pattern is demonstrated, which is an important step towards real world applications.     

2-μm single longitudinal mode GaSb-based laterally coupled distributed feedback laser with regrowth-free shallow-etched gratings by interference lithography

We report a type-I Ga Sb-based laterally coupled distributed-feedback(LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio(SMSR) as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature(uncoated facet). A low threshold current density of 230 A/cm~2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature.     

高功率980nm垂直腔面发射激光器的亮度特性

在循环水冷却(工作环境温度控制在15℃)和连续注入电流条件下,从垂直腔面发射激光器(VCSEL)亮度基本定义出发,实验测量了不同注入电流时口径为400μm的高功率980nm InGaAs/GaAs应变量子阱垂直腔面发射激光器(VCSEL)的亮度特性。结果表明:在注入电流4 A时,随着注入电流的增加,亮度也跟着增加;当注入电流4A时,尽管输出功率在增加,但是器件的光束质量变差,M2因子升高,表明此时影响器件亮度的主导因素是M2因子,所以亮度减小;在注入电流为4A,输出功率为1.2W时,亮度达到最大值2.43kW/cm2.sr,此时的光束质量最好,M2因子为207。最后,分析了影响高功率VCSEL器件亮度特性的主要因素,提出了提高器件亮度特性的解决方法。