InP基近红外波段量子线激光器的温度特性研究

制备了InP基近红外波段量子线激光器,在激光器温度特性分析中,观察到了反常的特征温度分布曲线.随着热沉温度增加,在120—180 K时,激光器阈值电流随温度升高出现下降趋势,即出现了负的特征温度.分析认为负特征温度的出现是由于随温度变化载流子再分布引起的.     

碲锡铅可调谐激光器的光谱特性

本文报道了用水平无籽晶气相生长法(HUVT)制造的可调谐二极管激光器的性能参数,在12K温度下,脉冲阈值电流密度为370A/cm~2,直流阈值电流密度为440A/cm~2.在13K温度下的电流调谐率为0.15cm~(-1)/mA.在400mA工作电流下的温度调谐率为2.3cm~(-1)/K.     

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。     

隐埋“月牙”形InGaAsP/InP激光器动态特性研究

本文用计算机模拟方法分析了隐埋“月牙”形InGaAsP/InP激光器的动态特性,得到阈值电流,单模截止条件与有源区厚度(中心)d₀、沟宽W、条宽s、腔长L和材料的电阻率R_x等结构参数间的关系。在模拟分析的基础上,提供了阈值电流与结构参数间的近似表示式,从中能简捷地估算激光器的物理特性。文内还提出了注入载流子浓度高斯分布模型,应用这模型,可准确地计算电流扩展和增益分布,且导出了最大增益g_max,阈值电流密度J_th,模增益G_th,最佳有源区(中心)厚度d_0,min,最佳阈值电流密度J_th,min等一系列解析式。基于上述分析,该激光器最佳设计参数为d₀=0.15—0.2μm,W=2—4μm,s=10—15μm,L=200μm。 关键词：     

分布反馈激光器实现室温连续工作

将光和载流子分开限制的分布反馈GaAs—GaAlAs二极管激光器,在直流偏压下,直到室温已成功地工作。该激光器受激发射单纵模的阈值电流密度在170°K时为0.94KA/cm~2,在300°K时为3.5KA/cm~2。     

煤粉挥发份析出规律的研究

本文提出了粉煤挥发份析出的通用热解模型。该模型与现有的其他模型相比,主要特点是挥发份析出时的化学动力学参数E、K不随煤种变化,仅是颗粒最终温度T_∞的函数。这是一个新的结论。本文还得到了E(或K)和T_∞间的关系,它适用于所有的煤种。若在一定条件下得到粉煤挥发份的最终产量V_∞,则可用该模型预示任何煤种的挥发份析出过程。 本文报道了烟煤、褐煤、劣质烟煤、贫煤在高温下降炉中、加热气体为Ar、N_2和He的条件下,其挥发份的析出过程。煤颗粒的加热速率大于10~4K/s,直径从35μm—100μm,温度范围为973—1773K,取样时颗粒的冷却速率大于10~5K/s。确定挥发份的产量利用灰作示踪剂。气体在高温反应炉内的流动是层流运动,且颗粒在下降过程中弥散很小。     

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。     

Y-Ba-Cu和Y-Gd-Ba-Cu氧化物超导电性的压力研究

在0—12kbar的压力下,在77—300K的温区里,研究了Y_1-Ba_2-Cu_3和Y_1-Gd_1-Ba_1-CU_3氧化物超导转变温度的压力效应。电阻测量采取标准直流四线方法。采用液体介质传压的Be-Cu自锁式压力装置。压力能提高这二种样品的偏离线性温度Tci 和零电阻温度Tcf。Y-Ba-Cu氧化物的Tcf平均增加率为0.71K/kbar,Y-Gd-Ba-Cu氧化物为0.27K/kbar。在Tci处的电阻率Pci随压力P增加而下降。     

空心针板放电等离子体气体温度和振动温度研究

使用空心针板放电装置,以氩气作为导入气体,在大气环境下产生了1.6~3 cm波长的等离子体炬。利用发射光谱法,研究了等离子体炬弧根和弧梢处的气体温度和振动温度,以及它们随气体流量的变化。等离子体气体温度通过对OH基309 nm附近的谱带进行拟合得到,等离子体振动温度由氮分子第二正带系C3Πu—B3Πg计算得到。实验发现弧根和弧梢处的气体温度相等,并随着气体流量的增大而下降。当气体流量从3.0 mL.min-1增大到6.5 mL.min-1时,气体温度由350 K下降到300 K。当气体流量较小(如3.0 mL.min-1)时,弧梢处的振动温度(1 950 K)高于弧根处的振动温度(1 755 K)。随着气体流量的增大,弧梢处与弧根处的振动温度均下降,但弧梢处下降速率较快。当气体流量较大时,二者趋于相等。     

PTS单晶的低温热电势率

用微分法测量了PTS单晶自77—273K的热电势率,结果表明PTS单晶的热电势率随温度而线性上升,在114K附近其值有突跃,在150K和220K附近其值急剧变小,出现下降峰。     

AlInGaAs/AlGaAs垂直腔面发射激光器温度特性的对比研究

通过测量、对比材料生长和器件制备条件基本相似，但是谐振腔腔模波长与增益峰值波长相对位置明显不同的两类氧化物限制型应变AlInGaAs/AlGaAs量子阱垂直腔面发射激光器(VCSEL)在261—369K温度范围内输出光功率-电流的变温曲线，同时结合测试得到的两类样品的白光反射谱、光荧光谱以及模拟计算得到的不同温度下VCSEL反射谱和增益谱，分析了输出光功率、阈值电流、斜率效率和激射波长随温度变化的关系，掌握了新材料AlInGaAs的温度特性，得到了谐振腔腔模波长和增益峰值波长的相对位置对VCSEL输出特性，尤其是对阈值的影响规律，指出获得室温工作阈值最低且稳定的VCSEL的一个方法是调整谐振腔腔模波长和增益峰值波长的相对位置，并利用这种方法获得了特征温度T₀=333K的AlInGaAs/AlGaAs量子阱VCSEL器件. 关键词： AlInGaAs 垂直腔面发射激光器 特征温度     

Systematic study on the confinement structure design of 1.5-μm InGaAlAs/InP multiple-quantum-well lasers

An in-dept analysis on the separate confinement heterostructure (SCH) design parameters of 1.5-μm InGaAlAs/InP multiple quantum-well (MQW) lasers is reported. Theoretical calculations show a drastic enhancement on threshold current and slope efficiency from step-index SCH (STEP-SCH) to graded-index SCH (GRIN-SCH) design, but the effect ceases beyond a critical number of grading steps. This finding implies ease of the growth process and reduction in cost. The overall GRIN-SCH’s thickness is found to exert great influence over the achievable laser’s threshold current and slope efficiency. An average of 27 mA threshold current reduction and more than 32% of slope efficiency increment were achieved by optimizing the GRIN-SCH thickness. Increasing the grading energy range of the GRIN-SCH decreases the slope efficiency, but is found to effectively reduce carrier leakage at elevated temperature leading to a less temperature-sensitive threshold current MQW ridge lasers were fabricated and characterized out of two laser materials, one with a reference STEP-SCH and another with a proposed optimized GRIN-SCH profile. The laser with optimised SCH design has shown a 36% reduction in room temperature threshold current as compared to that with the STEP-SCH design, which is in good agreement to the theoretical simulation. In addition, a record high characteristic temperature (T ₀) of 105 K was obtained on the GRIN-SCH laser structure, which is more than three fold increment as compared to the STEP-SCH design.     

MBE-grown Ridge-waveguide InGaAs/InGaAsP Strained Quantum Well Lasers at 2 μm Wavelength

The result of molecular beam epitaxy (MBE)-grown ridge-waveguide InGaAs/ InGaAsP/InP strained quantum well lasers at 2 μm wavelength is reported. The pulsed electrical luminescence spectrum at room temperature is observed with peak wavelength of about 1.98 μm. At 77 K the lasers become lasing in pulse regime, with threshold current of about 18～30 mA, peak wavelength of about 1.87～ 1. 91 μm, and single longitudinal mode operation in the current range of 160～230 mA.     

MBE-grown Ridge-waveguide InGaAs/InGaAsP Strained Quantum Well Lasers at 2 μm Wavelength

1 horottionFor a long time GaSh--based IILV antimonial material is the main material systemfor nddinfrared semiconductor l...[l' 2] because of its wide wavelength range Of 1. 7 4. 5 mp offering a convenient choice for different applications. HOwever there aredifficuhies in its material growth and device fabrication. Iall--based InGaAs/InGaAsPstrained QW Inaterial become attractive for nddinfrared semiconductor lasers because ithas relatively loW thermcrresistance and serial resistance a…     

Low-temperature performance of InP-based long-wavelength VCSELs

We have studied, for the first time, the parameters of long-wavelength InP-based buried tunnel junction (BTJ) VCSELs with substrate temperature varied in the range between 150 and 330 K. The BTJ-VCSELs with threshold currents <1 mA were designed by VERTILAS (Germany) to operate near 1512 nm and 1577 nm at room temperature (models VL-1512 and VL-1577, respectively). Reducing the substrate temperature of the lasers from room temperature to 150 K resulted in more than a fourfold increase of the threshold injection current accompanied with threefold and twofold increases in output power and slope efficiency, respectively. We have observed continuous single-mode tuning over intervals up to ∼20 nm (VL-1512) and ∼22 nm (VL-1577) at constant injection currents and substrate temperatures varied in a 180 K range. The emission wavelength was found to shift linearly with temperature with rates of 0.11 nm/K and 0.12 nm/K for lasers VL-1512 and VL-1577, respectively. The single-mode laser output reached ∼3 mW for both lasers cooled down to 173 K. Gas sensors based on BTJ-VCSELs can be temperature tuned over wide spectral intervals using either a cooler or a low ambient temperature to control laser substrate temperature. Ultra-sensitive gas concentration measurements under low ambient temperatures may include chemical analysis of the lower earth stratosphere and of the martian atmosphere. PACS 42.55.Px; 42.62.Fi; 39.30.+w     

A novel structure of visible semiconductor lasers

Terraced substrate inner current stripe lasers emitting in the range of 750–780 nm are developed with very simple fabrication processes. The lasers have good performance of cw room temperature, linear light-current output over 30 mW per facet and maintain stable fundamental transverse and longitudinal mode of 2–4 times current threshold. The current threshold of 25 mA under cw room temperature operation has been achieved.     

Temperature and injection current dependent electroluminescence study of GaInP/AlGaInP quantum well laser diode grown using tertiarybutylarsine and tertiarybutylphosphine

GaInP/AlGaInP triple quantum well (TQW) lasers, grown by metalorganic chemical vapor deposition (MOCVD) using tertiarybutylarsine (TBAs) and tertiarybutylphosphine (TBP), were fabricated with a pulsed anodic oxidation (PAO) process. The devices worked at room temperature (RT) with the lowest threshold current density (J_th) of 1.5 kA/cm² ever reported for GaInP/AlGaInP lasers grown using TBAs and TBP. Temperature dependent (35–250 K) electroluminescence (EL) study of the GaInP/AlGaInP laser diode showed almost the same luminescence quenching behavior at a high temperature region (120–250 K), independent of the injection current (100–150 mA). A model involving a nonradiative recombination mechanism was presented to interpret the EL quenching behavior over the experimental temperature range. The nonradiative recombination centers in the Al-containing barrier or cladding layer are believed to contribute to the loss of carriers via nonradiative recombination. PACS 78.60.Fi; 71.20.Nr; 78.67.De; 81.15.Gh; 42.55.Px     

长波长大应变InGaAs/InGaAsP分布反馈激光器的材料生长与器件制备

采用低压金属有机化合物气相沉积法(LP-MOCVD)生长并制作了1.6—1.7μm大应变InGaAs/InGaAsP分布反馈激光器.采用应变缓冲层技术，得到质量良好的大应变InGaAs/InP体材料.器件采用了4个大应变的量子阱，加入了载流子阻挡层改善器件的温度特性.1.66μm和1.74μm未镀膜的3μm脊型波导器件阈值电流低(小于15mA)，输出功率高(100mA时大于14mW).从10—40℃，1.74μm激光器的特征温度T₀=57K，和1.55μm InGaAsP分布反馈激光器的特征温度相当. 关键词： MOCVD InGaAs/InGaAsP 应变量子阱 分布反馈激光器     

Active region design of a terahertz GaN/ Al0.15Ga0.85N quantum cascade laser

We propose the idea of developing THz quantum cascade lasers (QCLs) with GaN-based quantum well (QW) structures with significant advantages over the currently demonstrated THz lasers in the GaAs-based material system. While the ultrafast longitudinal optical (LO) phonon scattering in AlGaN/GaN QWs can be used for the rapid depopulation of the lower laser state, the large LO-phonon energy (∼90 meV) can effectively reduce the thermal population of the lasing states at higher temperatures. Our analysis of one particular structure has shown that a relatively low threshold current density of 832 A/cm² can provide a threshold optical gain of 50/cm at room temperature. We have also found that the characteristic temperature in this structure is as high as 136 K.     

Modeling and experimental study of 780–808-nm AlGaAs/GaAs injection lasers with electron superlattice barriers

Electron superlattice barriers (ESBs) were used in AlGaAs/GaAs injection lasers to improve the electron confinement of the active layer by Bragg reflection of electron waves. The design of a separate-confinement heterostructure (SCH) laser with ESBs operating at 780–808 nm was optimized. Conventional SCH and SCH-ESB were prepared by low-pressure MOCVD epitaxy. Oxide stripe lasers with stripe widths of 100 and 200µm were prepared. The threshold current density of 0.3 kA/cm² and the characteristic temperature constantT ₀=220 K were measured at a wavelength of 808 nm for SCH-ESB lasers with an active-layer thickness of 40 nm and a resonator length of 0.4–0.5 mm. For conventional SCH lasers with the same geometry, a threshold current density of 0.42 kA/cm² andT ₀=160 K were obtained. Experimental results on the low-temperature photoluminescence characterizing ESB regions are presented and are compared with the calculated miniband energy spectrum of the superlattice structure. The leakage currents for ordinary SCH and SCH-ESB lasers were analyzed. Experimental verification of a reduction in the leakage current for SCH-ESB lasers was obtained.