1. Performance improvements of a terahertz direct detector for imaging arrays.
- Author
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Su, R F, Wang, H, Shi, L L, Wang, Y, Wu, J B, Tu, X C, Jia, X Q, Kang, L, Jin, B B, Xu, W W, Wang, H B, Wu, X L, Wang, X R, Chen, J, and Wu, P H
- Subjects
MICROWAVE devices ,SUBMILLIMETER waves ,MICROWAVE imaging ,HOT carriers ,SURFACE impedance ,COPLANAR waveguides ,RESONATORS ,IMAGE converters ,NUCLEAR counters - Abstract
We studied and improved the performance of a terahertz (THz) direct detector based on the superconducting NbN hot electron bolometer (HEB) integrated with microwave readout for imaging arrays and other applications. A 6 nm thick NbN microbridge at the feed point of a twin-slot antenna is embedded into a high-Q quarter-wavelength coplanar waveguide (CPW) resonator made from a 350 nm thick NbN film which is weakly coupled to a CPW feedline. THz direct detection was performed at a signal frequency of 0.66 THz at a bath temperature of 4.2 K. When operating at a low input microwave power level, the device acting as a microwave kinetic inductance detector with a kinetic inductance fraction of 0.45 changes the surface impedance of the resonator in response to incident THz radiation. The estimated optical noise equivalent power (NEP) is ∼0.23 pW · Hz
−0.5 which shows about one order of magnitude improvement compared to that of the traditional voltage-biased NbN HEBs. The improved performance of the THz direct detectors with lower NEP and easy readout makes them promising in imaging with a large number of the array pixels. [ABSTRACT FROM AUTHOR]- Published
- 2021
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