超宽带高灵敏度超导热电子混频器及阵列接收机技术

The terahertz (THz) frequency region of the electromagnetic spectrum is very rich in scientific and technological applications, and it is the unique wave band to understand molecular clouds, star formation region, planets and theirs system. Multiband and high spectral resolution observations can be used to study such scientific problems as galaxy formation and evolution, planet atmosphere. Ultra-wideband superconducting mixers with high sensitivity and array receiver may greatly enhance the telescope observation efficiency. Although superconducting hot electron bolometer (HEB) mixers are the heterodyne detector of the choice at frequencies above 1THz thanks to their quantum-limited sensitivity, their spectral and intermediate frequency (IF) bandwidths are not wide enough to meet the requirement of modern astronomical applications, especially it's a big challenge to build a large-format superconducting hot electron bolometer mixer array receiver. We will study superconducting HEB mixers with broad RF/IF bandwidth and array receiver, including physical mechanism of superconducting HEB mixer, extension of RF bandwidth with novel antennas, improvement of IF bandwidth with MgB2 superconductor, distribution of LO power with Fourier phase grating, low-noise amplifier chip-level integration. Finally we will demonstrate a high sensitive THz superconducting HEB mixer with broad RF/IF bandwidth and an array receiver. This project will promote the development of superconducting HEB mixer and array receiver for Dome A five-meter THz telescope, the next-generation large millimeter/submillimeter and terahertz telescope as well as future space THz missions.

太赫兹波段具有重要科学意义和丰富应用前景，是理解分子云、恒星形成区、行星及行星系统的独特波段。通过多波段、高频率分辨率观测可以研究星系形成和演化、行星大气等前沿科学问题，而超宽带高灵敏度超导混频器及其阵列接收机可以极大提高望远镜的观测效率。超导热电子混频器是1 THz以上灵敏度最高的相干探测器，但是其射频和中频带宽不能完全满足实际天文观测需求，仍有较大发展空间，同时构建大规模超导热电子混频器阵列接收机还存在巨大技术挑战。本项目将主要研究太赫兹超导热电子混频器的射频和中频带宽延展技术及其阵列接收机技术，包括超导热电子混频器的物理机理、射频带宽延展技术、中频带宽延展技术及模块化可扩展的阵列接收机技术，最终实现超宽带高灵敏度太赫兹超导热电子混频器及阵列接收机。本项目将为我国南极天文台五米太赫兹望远镜、下一代大口径毫米波/亚毫米波及太赫兹望远镜以及未来空间太赫兹计划打下关键技术基础。

太赫兹超宽带高灵敏度超导混频器及阵列接收机可极大提高大型天文望远镜的观测效率。本项目研究了超导热电子(Hot electron bolometer，HEB)混频器的探测机理、中频和射频带宽延展技术和本振功率分配技术等，最终实现了1×4像元的高灵敏度超导HEB混频器阵列接收机，噪声温度仅为600 K，中频带瞬时带宽大于7 GHz，射频带宽超过3倍频程。此外，还探索了高临界温度MgB2超导薄膜及HEB混频器的制备，采用混合物理化学气相沉积法制备了临界温度高达40 K的MgB2薄膜，通过聚焦离子束刻蚀定义超导微桥，成功研制了平面螺旋天线耦合的MgB2超导HEB混频器。这些研究成果将为我国的大口径亚毫米波望远镜及未来的空间太赫兹计划奠定关键技术基础，也为其他领域提供高灵敏度的太赫兹探测手段。