Eighth Symposium on Novel Photoelectronic Detection Technology and Applications

Design and performance analysis of NbN-based SIS mixer in the 750–950 GHz frequency band for LCT telescope

Fengqi Lyu, Weijie Du, Wangzhou Shi, Yiwen Zhang

Published Apr 4, 2023• 1 citation

Abstract

In order to expand the detection range of the LCT telescope, it is attractive to develop a high sensitivity Superconductor–Insulator–Superconductor (SIS) mixer with operating frequency higher than 680 GHz. In this study, we designed a SIS mixer with a center operating frequency of 850 GHz (covering from 750 to 950 GHz) using a high gap voltage material of NbN (Vgap = 5.4 - 5.6 mV) fabricated on MgO substrates. Simulations of electromagnetic fields and quantum mixing were applied to evaluate the performance of the designed SIS mixer. The width and length of the feed point were optimized to reduce the input reflection of the Local Oscillator (LO) input port (S11). In the frequency range of 750-950 GHz, a lowest S11 of less than -40 dB can be achieved using a feed point with a width of 4 μm and a length of 2.6 μm. It was observed that the embedded impedance was easily affected by the open angle of the feed point and the MgO substrate thickness. On the contrary, the deviation of the feed point showed less impact on the embedded impedance. The calculation results of quantum mixing showed that the noise temperature of the NbN-based SIS mixer was 323.4 K at 850 GHz, indicating that the designed SIS mixer has the potential to meet the requirements of manufacturing low noise high frequency receivers.

DOI: 10.1117/12.2666804

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