Application development of QC laser for THz band multi-beam heterodyne receiver

来自星际介质和行星大气中的气体种类的光谱线的一部分位于1-10太赫兹频段。在分析这些信号的同时，射电天文学领域的外差光谱提供了一个高频率分辨率，使我们能够研究物理和化学条件。然而，由于缺乏良好的观测地点和在该频率范围内工作的高灵敏度外差接收器的可用性，1-10太赫兹波段的天文学长期未被探索。未来太赫兹波段射电天文学的一个关键方面是多波束接收机的高效观测。工作在1-10太赫兹波段的输出功率在亚毫瓦范围内的量子级联激光器是多波束接收机的潜在候选本振。在这项研究中，我们开发了一个锁相环系统，利用超导NbTiN-HEB混频器直接锁相这种自由运行的太赫兹波段信号。

A certain portion of spectral lines from gas species in interstellar mediums, and planetary atmospheres lies in the 1-10 THz frequency band. In the light of analyzing these signals, heterodyne spectroscopy in the field of radio astronomy provides a high frequency resolution that allows us to study the physical and chemical conditions. However, astronomy in the 1-10 THz band has been long unexplored because of the lack of good observing sites and availability of high-sensitivity heterodyne receivers operating in this frequency range. One of the key aspects of future THz-band radio astronomy is the high efficient observations with multibeam receivers. Quantum cascade lasers with output powers in the sub-mW range operating at the 1-10 THz bands are potential candidates as local oscillators for multibeam receivers. In this study, we developed a PLL system to phase-lock such a free running THz-band signal directly by utilizing a superconducting NbTiN-HEB mixer.