High Sensitivity Terahertz Receivers Based on Plasmonic Photoconductors.

Abstract

Terahertz radiation has unique properties that enable new functionalities for various imaging and sensing applications, such as security screening, bio sensing, medical imaging, and astronomical studies, etc. Despite great benefits that terahertz radiation can offer to these applications, high-power terahertz transmitters and sensitive terahertz receivers are still in demand to realize practical terahertz systems.

This PhD research focuses on high sensitivity terahertz receivers based on plasmonic photoconductors. Two types of terahertz receivers have been studied to achieve high terahertz detection sensitivity levels. The first type is photoconductive terahertz receivers, which are widely used for detecting terahertz pulses in time-domain terahertz spectroscopy systems. By utilizing plasmonic contact electrodes in photoconductive terahertz receivers, significantly higher detection sensitivities can be achieved compared to conventional photoconductive terahertz receivers that do not use plasmonic contact electrodes. The second type of terahertz receivers that have been studied is plasmonic heterodyne terahertz receivers, which can be used to detect continuous wave (CW) terahertz radiation and provide accurate intensity and frequency information simultaneously. A novel scheme for heterodyne terahertz receivers based on plasmonic photomixers is presented, which replaces the terahertz local oscillator of conventional heterodyne receivers with two wavelength tunable lasers to provide large dynamic range and broadband operation at room temperature.