Integration of a field-effect-transistor terahertz detector with a diagonal horn antenna**Project supported by the National Key Research and Development Program of China (Grant Nos. 2016YFF0100501 and 2016YFC0801203), the National Natural Science Foundation of China (Grant Nos. 61611530708, 11403084, 61401456, 61401297, and 61505242), the Six Talent Peaks Project of Jiangsu Province, China (Grant No. XXRJ-079), the Youth Innovation Promotion Association of

Abstract

Efficient coupling of terahertz electromagnetic wave with the active region in a terahertz detector is required to enhance the optical sensitivity. In this work, we demonstrate direct integration of a field-effect-transistor (FET) terahertz detector chip at the waveguide port of a horn antenna. Although the integration without a proper backshot is rather preliminary, the noise-equivalent power is greatly reduced from 2.7 nW/Hz1/2 for the bare detector chip to 76 pW/Hz1/2 at 340 GHz. The enhancement factor of about 30 is confirmed by simulations revealing the effective increase in the energy flux density seen by the detector. The simulation further confirms the frequency response of the horn antenna and the onchip antennas. A design with the detector chip fully embedded within a waveguide cavity could be made to further enhance the coupling efficiency.