Lead salt quantum well diode lasers

Lead-salt diode lasers are useful for spectroscopic applications in the 2.5–30 μm wavelength range. These devices have previously required cryogenic cooling <100 K) for CW operation. The use of quantum well, large optical cavity structures has improved the operating temperatures to 174 K CW (at 4.39 μm) and to 270 K pulsed (at 3.88 μm). These diodes have a single PbTe quantum well with lattice-matched Pb_1?xEu_xSeyTe_1?y confinement layers grown by molecular beam epitaxy. The emission energy shifts have been calculated using a finite square well with nonparabolicity effects included. Initial work has also been done on multiple quantum well lasers. The maximum operating temperatures were comparable to those of single quantum well lasers, with leakage current and possibly Auger recombination limiting device performance.     

利用同步辐射光电子能谱技术测量ZnO/PbTe异质结的能带带阶

异质结结构界面的能带带阶是一个非常重要的参数,该参数的精确确定直接影响异质结的光电性质研究以及异质结在光电器件上的应用.利用同步辐射光电子能谱技术测量了ZnO/PbTe异质结结构的能带带阶.测量得到该异质结价带带阶为2.56 eV,导带带阶为0.49 eV,是一个典型的类型I的能带排列.利用变厚度扫描的测量方法发现,ZnO/PbTe界面存在两种键,分别是Pb—O键(低结合能)和Pb—Te键(高结合能).在ZnO/PbTe异质结界面的能带排列中导带带阶较小,而价带带阶较大,这一能带结构有利于PbTe中的激发电子输运到ZnO导电层中.该类结构在新型太阳电池、中红外探测器、激光器等器件中具有潜在的应用价值.     

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.     

IV–VI compound compositional and doping superlattices

Structural, electronic, optical and magnetooptical investigations on compositional superlattices (mainly PbTe/PbSnTe, PbTe/PbEuSeTe) are summarized. Recent results on transport and magnetooptical effects in PbTe doping superlattices are presented and examples for an excellent photoconductivity response of these structures in the 5μm region are given.     

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…     

InGaAsP/GaAs SCH SQW laser arrays grown by LPE

InGaAsP/InGaP/GaAs separate confinement heterostructure (SCH) single quantum well (SQW) laser structures have been obtained by an improved liquid-phase epitaxy (LPE) process. Wide-contact stripe lasers have been fabricated with threshold current density below 300 A/cm² and cavity length of 800 μm. Finally, with the same grown wafers, 1-cm bar laser diode (LD) arrays are made with 150 μm wide stripes and a maximum fill factor of 30%. Continuous Wave (CW) power output of 20 W has been reached.     

PbTe/CdTe量子点的光学增益

PbTe/CdTe量子点是一类新型异系低维结构材料,实验发现具有强的室温中红外光致发光现象.为研究这一材料体系的发光特性,建立了理论模型,计算了PbTe/CdTe量子点的光学跃迁和增益.模型基于k·p包络波函数方法并考虑了PbTe能带结构的各向异性.分析了量子点光学增益与量子点尺寸、注入载流子浓度的关系.结果表明,当注入载流子浓度在(0.3—3)×10¹⁸cm^-3范围时,尺寸为15—20nm的量子点可以产生 关键词： PbTe/CdTe量子点 光学增益 铅盐矿半导体     

非对称结构大功率940nm量子阱激光器

为改善940 nm大功率InGaAs/GaAs半导体激光器输出特性,通过模拟计算了非对称波导层及限制层结构的光场分布,并参照模拟制作了非对称结构半导体激光器器件。采用低压金属有机物气相沉积(LP-MOCVD)生长技术,获得了低内吸收系数的高质量外延材料,通过实验数据计算得到激光器材料内吸收系数仅为0.44mm~(-1)。进而通过管芯工艺制作了条宽100μm、腔长2000μm的940 nm半导体激光器器件。25℃室温10 A直流连续(CW)测试镀膜后器件阈值电流251 mA,斜率效率1.22 W/A,最大输出功率达到9.6 W,最大光电转化效率超过70%。     

26.3-W continuous-wave, diode-double-end-pumped all-solid-state Nd:GdVO4 laser operating at 1.34 μm

A high-power continuous-wave (CW) all-solid-state Nd:GdVO₄ laser operating at 1.34 μm is reported here. The laser consists of a low doped level Nd:GdVO₄ crystal double-end-pumped by two high-power fiber-coupled diode lasers and a simple plane-parallel cavity. At an incident pump power of 88.8 W, a maximum CW output of 26.3 W at 1.34 μm is obtained with a slope efficiency of 33.7%. To the best of our knowledge, this is the highest output at 1.34 μm ever generated by diode-end-pumped all-solid-state lasers.     

Double heterojunction lasers and quantum well lasers

The improved technology of compound semiconductor heterojunction preparation has resulted in very reliable CW, room temperature diode lasers for optical information read-out grown on p-type substrates on the one hand and very abrupt double heterojunction diode lasers based on quantum effects on the other hand. The influence of quantization effects on the emission wavelength, the threshold current and its temperature dependence are discussed. A distinction has been made between quantization due to strong magnetic fields giving rise to a one-dimensional electron gas (quantum wire) and quantization resulting from electrostatic and/or compositional changes (quantum well). The double heterojunction as a test structure to study carrier scattering into quantum wells, the phonon participation in the hot carrier relaxation process and optical flux guiding in graded heterojunctions have been emphasized.     

Reliability of 1.3-μm InGaAsP/InP laser diodes

Degradation mechanisms and methods for reliability improvement in 1.3-μm quaternary lasers for use in submarine fiber optic cable communications are reviewed. The reliable diode requires an optimized structure, such as a thin active layer and a narrow stripe width, to achieve a low threshold current I_th, high characteristic temperature T_o, and high maximum temperature for CW operation, T^CW_max. Accelerated long-term life test data predict an MTTF of ∼10⁷ h at room temperature for state-of-the-art optimized lasers with T_o ∼ 80 K, T^CW_max∼ 100°C, I_th ∼ 20 mA, and 5-mW optical power, which barely meets the system requirement. Based on the present rate of reliability improvement, a useful life of ∼10⁹ h is forecast by 1986.     

Recent progress in the development of type II interband cascade lasers

Type-II interband cascade lasers combine the advantage of an interband optical transition with interband tunneling to enable the cascading of type-II quantum well active regions as is done in type-I quantum cascade laser. The relatively high radiative efficiency resulting from interband optical transitions translates into very low-threshold current densities, and when combined with the high quantum efficiency of cascade lasers, this diode laser design has the potential to operate under cw conditions at room temperature with high output power. Experimental results have already demonstrated some of this potential including high differential external quantum efficiency (>600%), high peak output power (6 W/facet at 80 K), high cw power conversion efficiency (>17% at 80 K), and operation at 300 K under pulsed conditions. Recent work aimed at reducing device thermal resistance and increasing cw operating temperature is reviewed including the demonstration of significant reductions in thermal resistance (averaging 25 K/W or 40% for 1-mm-long devices), 80 K cw operation at 3.4 μm with high-power conversion efficiency (23%) and high differential external quantum efficiency (532%), and cw operation up to 214 K.     

Investigation of temperature characteristics of modern InAsP/InGaAsP multi-quantum-well TJ-VCSELs for optical fibre communication

Continuous-wave (CW) performance of modern 1.3-μm InAsP/InGaAsP multi-quantum-well (MQW) tunnel-junction vertical-cavity surface-emitting diode lasers (TJ-VCSELs) is investigated using our comprehensive self-consistent simulation model to suggest their optimal design for room and elevated temperatures. For increasing ambient temperatures, an increase in the VCSEL threshold current has happened to be mostly associated with the Auger recombination. Nevertheless, the InAsP/InGaAsP VCSELs have been found to exhibit encouraging thermal behaviour with the quite high value of maximal operating temperature of 350 K. It has been found that 5-μm devices seem to be the most optimal ones because they demonstrate both the room temperature (RT) threshold current equal to only 0.55 mA and maximum operating temperature equal to as much as 345 K. For these devices, the characteristic temperature T0 is equal to 92 K for 290–305 K, 51 K for 310–325 K and 29 K for 330–345 K. Therefore, the InAsP/InGaAsP VCSELs have been found to offer very promising performance both at room and elevated temperatures as sources of the carrier 1.3-μm wave in the fibre optical communication using silica fibres.     

Multiple quantum well structures and high-power lasers of gaas- algaas grown by metalorganic vapor phase epitaxy (MOVPE)1

GaAs/AlGaAs GRIN-SCH type multiple quantum well lasers with four wells of 11 nm GaAs, grown in an MOVPE chimney reactor, exhibit an output power as high as 110 mW/facet (CW, 30°C; 5 μm stripe) and 1.3 W/facet (pulsed, 30°C; 53 μm stripe) until catastrophic optical damage occurs. 2000 hours life tests conducted at 60°C and 15 mW CW show no noticeable degradation for the 5 μm stripe laser with a reflective coating on both facets. Raman spectroscopy on similar multiple quantum well structures with 65 GaAs wells is used to ascertain that the wells have minimum residual aluminum- content.     

GaSb-based mid-infrared 2–5 μm laser diodes

Laser diodes emitting at room temperature in continuous wave regime (CW) in the mid-infrared (2–5 μm spectral domain) are needed for applications such as high sensitivity gas analysis by tunable diode laser absorption spectroscopy (TDLAS) and environmental monitoring. Such semiconductor devices do not exist today, with the exception of type-I GaInAsSb/AlGaAsSb quantum well laser diodes which show excellent room temperature performance, but only in the 2.0–2.6 μm wavelength range. Beyond 2.6 μm, type-II GaInAsSb/GaSb QW lasers, type-III ‘W’ InAs/GaInSb lasers, and interband quantum cascade lasers employing the InAs/Ga(In)Sb/AlSb system, all based on GaSb substrate, are competitive technologies to reach the goal of room temperature CW operation. These different technologies are discussed in this paper. To cite this article: A. Joullié, P. Christol, C. R. Physique 4 (2003).     

外腔锁模多量子阱二极管激光器

报道一种用作光通讯光源的外腔锁模多量子阱结构半导体激光器，其脉冲宽度２～５ｐｓ，波长调谐范围为１．５２～１．５７μｍ，锁模频率０．５～１．０ＧＨｚ平均输出光功率为１ｍＷ。     

External cavity quantum dot tunable laser through 1.55 μm

The optical performance of InAs/InGaAsP quantum dot (QD) lasers grown on (1 0 0) InP was studied for three different material structures. The most efficient QD laser structure, having a threshold current of 107 mA and an external differential quantum efficiency of 9.4% at room temperature, was used to form the active region of a grating-coupled external cavity tunable laser. A tuning range of 110 nm was demonstrated, which was mainly limited by the mirror and internal losses of the uncoated laser diode. Rapid state-filling of the QDs was also demonstrated by observing the evolution of the spectra with increasing injected current.     

Multiple quantum well structures and high-power lasers of gaas- algaas grown by metalorganic vapor phase epitaxy (MOVPE)1

GaAs/AlGaAs GRIN-SCH type multiple quantum well lasers with four wells of 11 nm GaAs, grown in an MOVPE chimney reactor, exhibit an output power as high as 110 mW/facet (CW, 30°C; 5 μm stripe) and 1.3 W/facet (pulsed, 30°C; 53 μm stripe) until catastrophic optical damage occurs. 2000 hours life tests conducted at 60°C and 15 mW CW show no noticeable degradation for the 5 μm stripe laser with a reflective coating on both facets. Raman spectroscopy on similar multiple quantum well structures with 65 GaAs wells is used to ascertain that the wells have minimum residual aluminum- content.     

1.625-μm high-power strained multiple quantum well lasers for optical time-domain reflectometers

An optical output power exceeding 210 mW has been achieved using 1.625-μm strained multiple quantum well lasers at a forward current of 800 mA under pulsed operation. We introduced tensile-strained barrier layers to increase internal quantum efficiency. High quantum efficiency is attributed to improved of hole injection efficiency and suppressed electron overflow from wells. The 1.625-μm high-power lasers are expected to be applied to optical time-domain reflectometers, which enable regular communication light to be used.     

Optical and continuous-wave characteristics of V-grooved quantum well wire lasers confined by a p-n junction array

Role of the side-wall quantum wells in a V-grooved quantum well wire (QWW) is briefly reviewed by temperature-dependent photoluminescence, and then continuous-wave (cw) characteristics of QWW lasers confined by a p-n junction array are reported. In terms of the effectiveness in current confinement, very high power operation (over 11 mW) and a single longitudinal mode operation up to 8mW are achieved. Room-temperature threshold currents are measured to be 32.5 mA (pulsed) and 47.8 mA (cw) for a 200 m long uncoated cavity. The current- and temperature-tuning rates of the oscillation wavelength are as low as 0.038 nm/mA and 0.17 nm/°C, respectively.