In this paper, we report about the development, fabrication, and characterization of a balanced waveguide hot electron bolometer (HEB) receiver for the Atacama Pathfinder EXperiment telescope covering the frequency band of 1.25–1.39 THz. The receiver uses a quadrature balanced scheme and two HEB mixers, fabricated from 4- to 5-nm-thick NbN film deposited on crystalline quartz substrate with an MgO buffer layer in between. We employed a novel micromachining method to produce all-metal waveguide parts at submicrometer accuracy (the main-mode waveguide dimensions are 90$\,\times\,
180\mu{\hbox{m}}$). We present details on the mixer design and measurement results, including receiver noise performance, stability and “first-light” at the telescope site. The receiver yields a double-sideband noise temperature averaged over the RF band below 1200 K, and outstanding stability with a spectroscopic Allan time more than 200 s.
Purple Mountain Observatory as well as its collaborators is proposing to build a 5-m THz telescope (DATE5) at Dome A, Antarctic. Two THz heterodyne receivers, with one at 1.4 THz, are being considered as its first generation instrument. Here we report on the development of a 1.4-THz superconducting hot-electron bolometer (HEB) mixer for DATE5, which adopts a twin-slot antenna design. The direct-detection spectral (FTS) response of the 1.4-THz superconducting HEB mixer, with the HEB device fabricated at MSPU, has been measured, giving a frequency coverage of 0.8~1.5THz. And the measured FTS response appears in good agreement with the simulated one. Preliminary noise- temperature measurement at a lower frequency of 0.85 THz shows a receiver noise temperature of 1500 K. The estimated performance at 1.4 THz should be less than 1000 K in terms of the measured FTS response. Detailed simulation and experimental results will be presented.
In this paper, the performance of a twin-slot antenna coupled NbN superconducting HEB mixer based on a new device fabrication process is thoroughly investigated. The measured lowest double-sideband receiver noise temperature is about 600 K at 1.3 THz, and reduced to 300 K after eliminating all the quasi-optical losses. The spectral response of the HEB mixer is characterized by a Fourier Transform Spectrometer (FTS) and its calibrated spectrum is in good agreement with the simulated one. In addition, the far-field beam pattern of this HEB mixer is characterized by a near-field measurement technique. The measured results agree well with the simulations too.