太赫兹量子级联激光器锁相技术研究

The terahertz (THz) frequency region of the electromagnetic spectrum is very rich in scientific and technological applications, but it remains relatively unexplored due to the lack of effcient and convenient radiation sources.In recent years, a new coherent solid-state source-terahertz quantum cascade lasers (QCL) have been rapidly developed. However, a free-running THz QCL''s frequency is affected by environmental temperature fluctuations and power supply current noise, which makes it hard to be used in a high resolution spectroscopy. Thus, many research groups around the world are exploring various phase-locking technologies for THz QCLs. This project aims to phase lock a THz QCL to the harmonics of a low frequency solid-state source using a superconducting HEB mixer. This project is expected to 1)thoroughly characterize and optimize the emitted beam patterns of a THz QCL, and realize the efficient beam coupling between THz QCL and superconducting hot electron bolometer (HEB) mixer in a single crystat；2) realize the phase-locking of a THz QCL to the harmonics of a low frequency solid-state source (a multiplier chain) using a superconducting HEB mixer. This project will promote the development of a superconducting integrated heterodyne receiver at terahertz frequencies. It will be very useful for the application of THz QCLs in future space-borne and Dome A THz projects.

太赫兹频段具有重要科学意义和丰富应用前景，但该频段信号产生技术仍然亟待发展。近年来，一种新型太赫兹固态信号源技术-量子级联激光器取得了飞速发展，但自由振荡量子级联激光器的输出频率受温度波动和偏置电流噪声影响，难以满足高精度高频率分辨率应用需求，为此，欧美等发达国家正积极开展太赫兹量子级联激光器锁相技术研究。本申请项目拟针对太赫兹集成接收机系统，以固态半导体源高次谐波为参考源，开展基于高灵敏度超导热电子混频器的太赫兹量子级联激光器锁相技术研究，主要研究内容包括: 1)表征并优化太赫兹量子级联激光器波束特性，在同一低温环境下实现太赫兹量子级联激光器与超导热电子混频器之间信号高效耦合；2)以固态半导体源谐波为参考源，基于超导热电子混频器实现太赫兹量子级联激光器高效锁相。本申请项目将为发展太赫兹高频段及远红外波段集成接收机打下基础，也为太赫兹量子级联激光器在南极后续和空间天文计划中应用打下基础。

太赫兹频段具有重要科学意思和丰富应用前景，但该频段信号产生技术和混频探测技术仍然亟待发展。本项目主要研究了一种新型太赫兹固态信号源-太赫兹量子级联激光器的集成与锁相技术，同时研究了太赫兹超导热电子混频探测技术。本项目取得的主要研究进展包括：1）成功在同一低温环境下实现太赫兹波段超导热电子混频器与量子级联激光器高集成度外差混频接收机；2）提出了采用固态半导体源谐波作为锁相参考源，成功基于单一超导热电子混频器同时实现太赫兹信号源锁相与信号相干检测；3）首次解明了超导热电子混频器对太赫兹辐射的非均匀吸收特性。本申请项目将为发展太赫兹高频段及远红外波段集成接收机打下基础，也为太赫兹量子级联激光器和超导热电子混频器在南极后续和空间天文计划中应用打下基础。