太赫兹量子级联激光器荧光增益谱的研究

Due to its unique properties such as compact size, high power and easy for integration, terahertz (THz) quantum cascade laser (QCL) is an important kind of high power source in the THz spectrum range, and has great potential application in the THz telecommunication and imaging. Nowadays, more and more researchers become highly interested in the novel functional devices, such as THz comb, THz optical amplifier and THz mode locked laser. In this project, we will develop measurement method for the fluorescent gain spectrum of the THz QCL, obtaining complete fluorescent gain spectrum in the current range from 0 to the subband misalignment point. We will design suitable waveguide structure for the sample device and improve the experiment system based on Fourier transform infrared spectroscopy, so that the spectrum of weak THz wave could be detected correctly and has higher signal to noise ratio. The fluorescent gain spectrum is a fundamental parameter for developing simulation tools for THz quantum devices, and it is also the basis to design more complicated THz functional devices, such as THz coupled-cavity optical amplifier and THz mode locked laser.

太赫兹（THz）量子级联激光器（QCL）具有体积小、轻便、功率高和易集成等特点，是THz波段一种重要的高功率辐射源，在THz通信和成像方面有广阔的应用前景。基于THz QCL结构的各种新型功能性器件，如THz光梳、THz光放大器和THz锁模激光器，是本领域当前的研究热点之一。本项目拟开发THz QCL荧光增益谱的测量方法，在子带失配临界点以下的整个电流范围内，得到完整的荧光增益谱。通过设计合适的THz QCL样本器件波导结构，改进基于傅立叶变换红外光谱仪的实验系统，将提高THz光探测结果的信噪比，解决准确测量微弱THz波频谱的问题。项目得到的荧光增益谱一方面是建立THz量子器件仿真工具的依据，另一方面为研制THz耦合腔光放大器和锁模激光器等更为复杂的THz波段功能器件奠定基础。

本项目围绕太赫兹量子级联激光器荧光增益谱的测量，在样本器件设计制作、荧光增益谱测量系统设计搭建等方面展开研究，研究成果可以充分表征太赫兹量子级联激光器结构和内部动态过程，对推动太赫兹技术发展具有积极作用。取得的研究成果总结如下：.1. 从太赫兹量子级联激光器有源区结构设计、分子束外延生长、波导模式分布、器件工艺制程等方面展开系统研究，设计并制作高功率连续波太赫兹量子级联激光器，在1-5 THz范围内，实现80 mW高功率连续波输出，脉冲功率1.2 W。.2. 基于太赫兹量子阱探测器，实现对太赫兹量子级联激光器调制光的探测，获得6.2 GHz的调制响应带宽。.3. 基于本项目中高功率连续波太赫兹量子级联激光器，在太赫兹激光器远场特性改善，太赫兹成像关键技术、太赫兹主动/被动锁模、太赫兹光频梳及双光梳等热点研究领域取得突破。