基于InGaAs量子阱的VECSEL增益芯片的材料研究

发布时间：2019-06-06 17:11

【摘要】：垂直外腔面发射半导体激光器(VECSEL)是近几年发展起来的一种新型的光电子器件。它成功地将固体薄片激光器外腔的可扩展性和半导体激光器波长的可调整性等优点结合在一起,不仅能获得高输出功率和高光束质量,还可以方便地进行内腔倍频和调Q、锁模操作等,成为半导体激光和光电子技术交叉学科中的研究热点之一。因此本论文开展了基于InGaAs量子阱的VECSEL增益芯片的材料研究,并在此基础上初步进行了光泵浦垂直外腔面发射半导体激光器的制作。首先,通过分布布拉格反射镜(DBR)的反射率和带宽理论,增益材料的应变理论和增益理论,对DBR和多量子阱有源区(MQWs)进行了理论计算和结构设计,在此基础上设计了 VECSEL增益芯片的完整结构。其次,通过金属有机气相外延技术(MOVPE)对所设计的结构进行材料制备,并采用高分辨率X射线衍射(XRD)、室温光致发光(PL)、扫描电子显微镜(SEM)、以及分光光度计等测试来验证我们所设计的增益芯片的生长情况。DBR的测试结果表明厚度误差保持在3%左右,阻带g约100 nm中心在997 nm。多量子阱有源区的发光波长在961 nm—1000.6 nm范围内可以通过线性控制TMIn流量来进行调整,但随着发光波长变长,InGaAs多量子阱层的应变失配分别是从0.81%增加到1.18%,且有源区的发光特性变差。增益芯片的测试结果表明外延材料晶体品质较好,厚度满足精度,DBR区的反射谱和量子阱的发光谱能很好匹配。此外,针对VECSEL增益芯片PL谱中出现的不同于多量子阱有源区单个发光峰的多个峰值现象,我们分析认为增益芯片的PL谱是受到DBR结构和其他结构层干涉作用后受到调制的面发射PL谱。最后,设计并搭建了光泵浦VECSEL的光路,采取衬底刻蚀和水冷制冷相结合的方法去除增益芯片在工作过程中所产生的废热,采用808 nm半导体激光器作为光泵浦源。入射光功率小于3W时,VECSEL增益芯片的泵浦光吸收率可达80%左右。光泵浦正序VECSEL器件在955.3 nm和1011 nm处,光泵浦反序VECSEL器件在1113 nm处得到较强的光输出。
[Abstract]:Vertical external cavity surface emitting semiconductor laser (VECSEL) is a new type of optoelectronic device developed in recent years. It successfully combines the expansibility of the external cavity of the solid-state thin chip laser with the adjustable wavelength of the semiconductor laser. It can not only obtain high output power and high beam quality, but also conveniently carry out intracavity frequency doubling and Q-switching. Mode-locked operation has become one of the research hotspots in the interdisciplinary subject of semiconductor laser and optoelectronics. Therefore, the material research of VECSEL gain chip based on InGaAs quantum well is carried out in this paper, and on this basis, the fabrication of optically pumped vertical external cavity surface emitting semiconductor laser is carried out. Firstly, through the reflectivity and bandwidth theory of distributed Prague mirror (DBR), the strain theory and gain theory of gain materials, the theoretical calculation and structure design of DBR and multi-quantum well active region (MQWs) are carried out. On this basis, the complete structure of VECSEL gain chip is designed. Secondly, the designed structure was prepared by organometallic vapor phase epitaxial (MOVPE), and high resolution X-ray diffraction (XRD),) was used to photoluminescence (PL), scanning electron microscope (SEM),) at room temperature. And spectrophotometer to verify the growth of the gain chip we designed. DBR test results show that the thickness error is about 3%, and the stopband g is about 100 nm center at 997 nm.. The luminous wavelength of the active region of the multi-quantum well can be adjusted by linearly controlling the flow rate of TMIn in the range of 961 nm-1000.6 nm. However, with the prolongation of the luminous wavelength, the strain mismatch of the InGaAs multi-quantum well layer increases from 0.81% to 1.18%, respectively. And the luminous properties of the active region become worse. The test results of the gain chip show that the crystal quality of the epitaxial material is good, the thickness of the epitaxial material meets the accuracy, and the reflection spectrum in the DBR region can match well with the emission spectrum of the quantum well. In addition, in view of the multi-peak phenomenon in the PL spectrum of VECSEL gain chip, which is different from the single luminous peak in the active region of multiple quantum wells, It is considered that the PL spectrum of the gain chip is a surface emission PL spectrum modulated by the interference of DBR structure and other structural layers. Finally, the optical path of optically pumped VECSEL is designed and built, and the waste heat produced by the gain chip is removed by substrate etch and water-cooled refrigeration. 808 nm semiconductor laser is used as the optical pumping source. When the incident optical power is less than 3W, the pump optical absorptivity of VECSEL gain chip can reach about 80%. The optically pumped positive sequence VECSEL device has a strong optical output at 955.3 nm and 1011 nm, and the optically pumped reverse sequence VECSEL device has a strong optical output at 1113 nm.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248.4

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