808 nm掺铝半导体激光高损伤阈值腔面膜制备

研究了808 nm量子阱脊型波导结构掺铝半导体激光器在空气中解理不同镀膜方法对激光损伤阈值的影响.将半导体激光器管芯分别采用前后腔面不镀膜、前后腔面镀反射膜和前后腔面先镀钝化薄膜,再镀腔面反射膜的方法进行对比.测试半导体激光器输出功率的结果表明:腔面镀钝化薄膜的方法比只镀腔面反射膜的方法的激光损伤闽值高36%,并且能有效防止灾变性光学镜面损伤,同时,还分析了半导体激光器管芯和光学薄膜之间发生的物理效应.在大功率半导体激光器芯片腔面上镀钝化薄膜是提高其激光损伤阈值的一个行之有效的方法.     

大功率半导体激光器腔面的光学结构优化

采用转换矩阵的处理方法,对大功率半导体激光器腔面光学灾变阈值与膜层结构的关系进行了分析.从理论上给出了膜层的设计方法和计算结果,解释了不同腔面反射率对应的腔光学灾变阈值变化的实验结果,并首次提出后腔面的优化结构以避免后腔面烧毁.     

基于腔面非注入技术的大功率半导体激光器

采用腔面电流非注入技术,提高了808nm半导体激光器灾变性光学损伤(COD)阈值。通过腐蚀GaAs高掺杂层的方法,在半导体激光器腔面附近形成电流非注入区,以此来减少腔面处的载流子注入。载流子注入水平的降低,减少了腔面处非辐射复合的发生,因而提高了激光器的灾变性光学损伤阈值。应用电流非注入技术制作的器件的最大输出功率达到3.7W;而应用常规工艺制作的器件的最大输出功率为3.1W。同常规工艺相比,采用该技术使器件的最大输出功率提高了近20%。     

基于AlxNy绝缘介质膜的新型窗口大功率半导体激光器

提升半导体激光器的腔面抗光学灾变(COD)损伤的能力,改善半导体激光器的工作特性,一直是大功率半导体激光器器件工艺研究的难点.基于薄膜应力使基底半导体材料带隙变化的原理,采用直流磁控溅射方法在不同条件下溅射生成不同内应力的AlxNy绝缘介质膜.通过研究大功率半导体激光器腔面退化机理,借助AlxNy等应力膜设计制作了一种新型非吸收透明窗口结构的宽条形半导体激光器,使器件平均最大输出功率提高46.5%,垂直发散角达到21°,水平发散角达到6.1°,2000 h加速老化试验,其千小时退化速率小于0.091%.     

915 nm半导体激光器新型腔面钝化工艺

针对半导体激光器腔面光学灾变损伤的发生机制,设计了一种单管芯半导体激光器腔面真空解理钝化工艺方法。在真空中解理并且直接对半导体激光器腔面蒸镀钝化膜,提出用ZnSe材料作为单管芯半导体激光器真空解理工艺的钝化膜材料,发现利用真空解理钝化工艺方法和ZnSe材料作为钝化膜可以使器件输出功率提高23%。通过电致发光（EL）对半导体激光器腔面损伤机理进行分析。进一步说明对915 nm半导体激光器制备工艺中引入真空解理钝化工艺技术并且选择ZnSe作为钝化膜可以有效保护半导体激光器腔面,提高器件可靠性。     

国内大功率半导体激光器研究及应用现状

近年来,国内外在大功率半导体激光器方面的研究均取得了很大的进展。其中,大功率半导体激光器列阵的研究和应用成为最大的亮点,如超高电光转换效率、高亮度和高可靠性等主要光电特性均实现了巨大的突破。针对国内大功率半导体激光器主要研究内容和关键技术进行了总结,在外延片结构中广泛采用应变量子阱结构、无铝有源区宽波导大光腔结构及非对称波导结构来提高端面光学灾变损伤光功率密度,还从腔面光学膜、器件封装、器件可靠性、光束整形与耦合以及器件应用等几个方面给予介绍。     

锗基InAs量子点激光器的腔面失效及再生的研究

围绕锗基InAs量子点激光器,开展了激光器腔面失效及再生的研究.研究并分析了灾变性光学镜面损伤产生的机理及其对激光器腔面的影响,开展了腔面再生研究,发展了一套创新性的腔面再生工艺并实现了失效的锗基InAs量子点激光器的再生.根据锗基InAs量子点激光器材料结构设计腐蚀工艺,通过选择性腐蚀在激光器腔面制备出悬臂结构,采用细针解理使悬臂结构自然解理,获得新的激光器谐振腔面,失效激光器重新工作.对比了激光器失效前和再生后的工作性能,结果表明因灾变性光学镜面损伤而失效的锗基InAs量子点激光器获得全新的谐振腔面,锗基激光器器件性能和失效前相当.     

大功率半导体激光器腔面抗烧毁技术

首先介绍了连续激光器单管老化试验,试验通过测试不同老化时间激光器腔面的烧毁功率,对腔面烧毁发生的过程进行了分析。分析认为,大功率半导体激光器腔面烧毁失效的根本原因是腔面烧毁功率在老化过程中持续减小,最终低于激光器输出功率,造成激光器灾变性光学镜面破坏(COMD)。随后对腔面烧毁的微观物理机理进行了介绍,重点讨论了腔面缺陷相关的非辐射复合、量子阱带边吸收、自由载流子吸收造成的腔面温度升高以及腔面高温导致腔面缺陷密度增加并且向腔内攀移的微观过程。最后,介绍了电流非注入腔面、大光腔材料、长腔长设计、腔面离子铣钝化工艺等腔面抗烧毁技术研究情况,并对这些技术提高腔面抗烧毁功率以及改善腔面长期稳定性的效果进行了讨论。     

808nm连续输出13.6W单芯片大功率激光器

通过对大功率激光器腔面光学灾变损伤的研究,分析了激光器腔面镀膜的损伤机理。为了提高激光器的输出功率,采用TiO_2替换Si作为高折射率材料,建立非标准膜系降低电场强度,同时优化膜层材料的粗糙度,并采用离子源进行清洗和助镀,有效提高了激光器的腔面光学灾变损伤阈值。结果表明,所制作的808nm激光器,最大连续输出功率达到13.6 W。     

550 K高温下激光器腔面温度的影响研究

针对激光器长期高温工作时腔面温度急剧升高产生灾变性光学损伤(COD)的问题,文章提出在半导体激光器腔面处加入Al₂O₃膜和陶瓷隔热共同作用,其可以降低激光器腔面温度,防止COD的产生。文章首先建立了半导体激光器简化模型分析固体传热。然后对550 K高温下无镀膜无隔热结构、有镀膜无隔热结构、无镀膜有隔热结构及镀膜与隔热结构共同作用时激光器模型的腔面温度进行仿真。其中镀膜选用Al₂O₃,隔热结构选用陶瓷隔热,腔面材料选用GaAs,热沉选用Cu热沉,接触层选用AlGaAa。4组对比实验结果表明,镀膜与隔热结构共同作用时,能将激光器的腔面温度控制在393.15 K以下。550 K高温在激光器腔面处镀膜和隔热结构双重作用下,能够有效防止COD产生,提高激光器的使用寿命。     

GaInAsP/GaInP/AlGaInP MOCVD-grown diode lasers emitting at 808 nm

The MOCVD epitaxy has been used to grow the GaInAsP/GaInP/AlGaInP laser heterostructures with a narrow symmetric waveguide and broad asymmetric waveguide. Mesa stripe 100 μm aperture diode lasers emitting at 808 nm were manufactured. It is shown that a SiO₂/Si dielectric mirror coating of Fabry-Perot faces of Al-free semiconductor lasers does not result in catastrophic optical mirror damage. It is found that the maximum optical output power of Al-free diode lasers is limited by catastrophic optical damage of the laser heterostructure. Maximum values of optical output power of 5.1 and 9.9 W have been attained in diode lasers with a narrow symmetric waveguide and broad asymmetric waveguide, respectively.

     

Improved catastrophic optical mirror damage level in InGaAs/AlGaAslaser diodes

9.2 W continuous wave (CW) optical power at a heatsink temperature 10°C and 12.2 W in a regime with stabilised temperature of the laser chip is demonstrated from a 100 μm aperture InGaAs/AlGaAs (λ=1.03 μm) laser diode with 0.4 μm wide GaAs waveguide. Thus, record-high optical power densities of 30 MW/cm² and 40 MW/cm² correspondingly are achieved at the front facet without catastrophic optical mirror damage (COMD)     

Imaging Catastrophic Optical Mirror Damage in High-Power Diode Lasers

We image catastrophic optical mirror damage (COMD) in red- and infrared-emitting high-power broad-area diode lasers by combining highly COMD-selective thermography, near-field imaging, scanning electron microscopy, and cathodoluminescence. All techniques exhibit strong correlations in terms of COMD location and strength and allow for an unambiguous decision about COMD occurrence. In particular, temperatures en route to and during COMD are measured, and the concept of a critical facet temperature that induces thermal runaway is supported.     

An AlGaAs laser with high-quality dry etched mirrors fabricatedusing an ultrahigh vacuum in situ dry etching and deposition processingsystem

Highly reliable AlGaAs lasers with dry etched mirrors have been successfully fabricated with an ultrahigh-vacuum in situ processing system, equipped with reactive ion-beam etching (RIBE) and dielectric film deposition chambers. Etched mirror surfaces are protected against air-exposure contamination and nonvolatile-reaction-products adsorption with in situ Al₂O₃ passivation subsequent to the CI₂ RIBE mirror formation. Ion-bombardment-induced damage is repaired by thermal annealing. The annealing effect is enhanced by a contamination-free interface between the etched mirror surface and Al ₂O₃ passivation film. The lasers exhibit an increase in catastrophic optical damage (COD) level and long-life operation. Their COD levels are twice as high as that for as-etched lasers and are almost the same as those for conventional cleaved lasers     

Thermal management strategies for high power semiconductor pump lasers

Semiconductor pump lasers are an important component in erbium-doped fiber amplifiers and Raman amplifiers. Thermal management has become one of the major obstacles of pump laser development. Understanding of the thermal behavior of high-power laser packages is crucial to the thermal design and optimization of pump lasers. In this paper, we report on the thermal characteristics of a high-power pump laser and discuss the issues associated with heat dissipation. The thermal management of high-power pump laser modules mainly consists of three aspects. One is the thermal resistance reduction which reduces bulk temperature rise in the laser diode chip. The second is facet temperature control, and the third is the thermoelectric cooler (TEC) coefficient of performance improvement. In this paper, the approaches to reduce thermal resistance and facet temperature at the chip level and package level will be reviewed, and the thermal design and optimization of the package assembly to improve the TEC coefficient of performance will be discussed. The thermal resistance of a pump laser could be reduced up to 40% by the proper design of the laser chip and epi-down bonding. An unpumped window design in the pump laser diode is proven to be very effective in reducing the facet temperature and increasing the catastrophic optical mirror damage level. Assembly and package optimization can provide more uniform temperature distribution on TEC cold plate which is critical in improving the TEC coefficient of performance.     

横向微堆积大功率半导体激光器线阵的制备

提出了一种横向微堆积大功率半导体激光器线阵的新结构,在相同的注入电流下提高了器件的输出光功率,有效缓解了大电流下的器件热烧毁和光学灾变性毁坏(COD)。制备了横向微堆积三有源区半导体激光器线阵列,在50A的工作电流下,其输出光功率可达到79.3W,斜率效率可达1.81W/A,是传统单有源区bar条的两倍多。     

Thermoreflectance calibration procedure on a laser diode: application to catastrophic optical facet damage analysis

In this letter, we present a thermoreflectance setup specially designed for the study of the temperature variations of the output facet of a laser diode. Indeed, the temperature of the laser diode is controlled by a Peltier element and the device under test is used as a temperature sensor. We propose a calibration procedure based on electrical measurements combined with optical ones; it leads to the determination of thermoreflectance coefficients and then to absolute temperature variations on a running laser diode. We can hence ensure a proper running of the diode and avoid its catastrophic optical facet damage.     

High efficiency, high power 808nm laser array and stacked arrays optimized for elevated temperature operation

Operation of 808-nm laser diode pumping at elevated temperature is crucial to many applications. Reliable operation at high power is limited by high thermal load and low catastrophic optical mirror damage (COMD) threshold at elevated temperature range. We demonstrated high efficiency and high power operation at elevated temperature with high COMD power. These results were achieved through device design optimization such as growth conditions, doping profile, and materials composition of the quantum-well and other layers. Electrical-to-optical efficiency as high as 62% was obtained through lowered threshold current, lowered series resistance and increased slope efficiency. The performance of single broad-area laser diodes scales to that of high power single bars on water-cooled copper micro-channel heatsinks or eonductively-cooled CS heatsinks. No reduction in bar performance or significant spectral broadening is seen when these micro-channel coolers are assembled into 6-bar and 18-bar CW stacks for the h     

光学薄膜弱吸收测试装置参数优化

光学薄膜对入射光的弱吸收特性是评价元件质量的重要参数.在高能激光作用下,即使十分微弱的吸收也将足以导致薄膜元件的灾难性破坏.因此,有必要对光学薄膜的平均吸收及局部吸收进行精确、快速、实时的检测.从光热偏转技术发展而来的表面热透镜法由于其对测试装置要求的放宽,并且同样拥有较高的测试精度,是测试元件薄膜弱吸收特性的有效方法...     

Near-field emission from GaAs double-heterostructure laser mirrors

The near fields of GaAs double-heterostructure (DH) laser mirrors are studied both in photoluminescent (PL) excitation and in lasing emission. The various liquid-phase-epitaxial (LPE) layers of the laser diode are optically delineated, withmp0.1-mum resolution, in a wavelength-selective PL detection system. The near fields of the transverse lasing modes are correlated with the LPE layers that constitute the optical waveguide. With special emphasis on the large-cavity fundamental-mode Ppn'N laser, it is found that small changes in refractive index within the waveguide have pronounced effects on the distribution of stimulated power within the LPE layers. The fundamental mode is found to be contained within the slightly higher refractive-index gain region. This explains the previously observed localization of catastrophic mirror damage and the anomalously large angles of beam divergence. High-order modes are also excited in the gain region when its thickness and refractive-index step within the waveguide exceed some prescribed limits.