面向高温工作面发射激光器的新型铟基阱岛复合量子发光结构及其调控方法研究

The optical gain spectra of traditional quantum wells or quantum dot behaves narrow width of about 20nm (Full width at half maximum, FWHM), with its temperature coefficient of more than 0.3nm/℃. Due to the output wavelength of VCSELs, which is corresponding to the cavity mode, is essentially depended on the refractive index of materials, thus the temperature coefficient of the output wavelength is only about 0.026nm/℃.The thermal drift of gain peak is ten times more than that of the output wavelength, thus the available gain of VCSELs would decrease rapidly due to the gain peak and cavity mode detuning caused by the increased operating temperatures. This induces the instable operation of VCSELs at different temperatures, especially at high temperatures. However, as cost- and energy-effective optical component, the VCSEL must satisfy the requirement of stability at high temperatures for a very wide field of novel applications. And how to solve the mismatch between the gain peak and cavity mode for VCSELs at different temperatures has been a difficult problem to scientists all over the world for a long time..The project aims to develop the pioneering material and structure of active region within VCSELs, based on our recent research findings on the novel complex quantum well and island. The gain spectra – cavity mode matching can be realized for an ultra wide range of operating temperatures in this project. And the historic breakthrough is expected to be gained during our investigations. In this project, we will focus on the simulation, demonstration and characterization of VCSELs based on the InGaAs and (Al)GaAs materials. The research contents in this project are as follows:.Firstly, investigations on the formation process and growth kinetics of complex quantum well and island will be carried out. And the effective method about how to control the composition and thickness of this new structure will be built up. Secondly, the thermal luminescence mechanism of In-based quantum well and island will be clarified, including its complex energy band structure, gain characteristics and its lasing. Thirdly, the fabrication and characterization of VCSELs with the active region composed by the newly developed quantum well and island structure will be carried out. Fourthly, the luminescence of In-based quantum well and island samples will be systematically characterized and analyzed. According to the above research, the gain spectra of proposed new active region of VCSELs will be broadened to be five times more than traditional structures.

长期以来，传统结构量子阱或量子点的光学增益由于带宽窄和随温度显著变化的固有特性使腔模可获得的增益因热漂移的存在迅速减少，以致器件发光性能随温度变化急剧波动，这极大地限制了垂直腔面发射激光器（VCSEL）的应用性。对该问题的解决不仅意义重大，也是至今国际上一直未能解决的极具挑战性课题。对此，本项目基于前期工作提出一种开创性的铟基阱岛复合量子发光结构VCSEL激光器，在极宽的温度范围内基本消除增益热移对激光器性能的影响，以取得历史性突破。主要研究内容包括：1.研究InGaAs材料中基于富铟岛效应的铟基阱岛混合量子结构生长动力学，建立有效调控铟基阱岛量子结构的生长工艺；2. 研究铟基阱岛量子结构热发光机制，包括复杂应变能带结构、增益和激射等；3. 铟基阱岛量子结构作为有源区的VCSEL制备；4.铟基阱岛量子结构及发光特性的实验研究。最终实现消除增益热移影响的光谱范围达到传统增益带宽的五倍以上。

长期以来，传统结构量子阱或量子点的光学增益由于带宽窄和随温度显著变化的特点使得激光器可获得的增益因热漂移的存在迅速减少，因而器件发光性能随温度变化急剧波动，极大限制了半导体激光器的环境适应性。本项目揭示并研究了富铟团簇量子限制结构的发光机理与特殊的光谱特性，构建了用于描述阱岛复合量子结构中铟分布及其复合能带结构的模型。证实这种特殊结构的辐射光谱是由In0.17Ga0.83As正常层以及大量不同组分的InxGa1-xAs缺铟层共同辐射叠加产生，这种特殊的富铟团簇量子限制结构展现出来极好的增益光谱展宽特性，可以实现宽达100nm的超宽增益带宽，并且以顶部特征分布均匀。利用这种团簇状量子限制结构特殊的能带结构，实现了激射波长为970nm和980nm稳定的双频输出，激光器阈值电流在25-85℃温度范围内漂移量低于±5%。本项目研究成果发表论文20篇，其中SCI论文17篇；授权发明专利10项；培养博士研究生3人；硕士研究生1人。研究成果“富铟团簇量子结构的超凡光学特性”获“2019中国光学十大进展”候选推荐。