High-sensitivity, broadband terahertz detectors based on plasmonic nano-antenna arrays

Abstract

We present a novel photoconductive terahertz detector, which offers significantly higher detection bandwidths and sensitivities compared to the state-of-the art. The detector is based on 2D plasmonic nano-antenna arrays, which are designed to concentrate a major fraction of an incident terahertz and optical pump beam at the same nanoscale regions in their close proximity. When the optical pump beam excites the detector, a large number of photocarriers are drifted to the plasmonic nano-antennas by the induced terahertz field to form the output current of the detector. The nano-antennas are also designed to offer high terahertz electric field enhancement factors over a broad terahertz frequency range. As a result, high-sensitivity and broadband operation is achieved simultaneously. We experimentally demonstrate pulsed terahertz detection with record-high signal-to-noise ratios as high as 107 dB over a 5 THz frequency range, which is 50 times higher compared to the state-of-the art.