Detection and upconversion of three-dimensional MMW/THz images to the visible

Abstract

We present an inexpensive technique to obtain a three-dimensional (3D) millimeter wave (MMW) and terahertz (THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/ THz radiation to the visual band using a very inexpensive miniature glow discharge detector (GDD) and a silicon photodetector. We present MMW/THz upconversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results show better response time and better sensitivity compared to the electronic detection performed previously. Furthermore, in this work we perform frequency modulation continuous wave (FMCW) radar detection based on this method using a GDD lamp, with a photodetector to measure GDD light emission. By using FMCW detection, the range in addition to the intensity at each pixel can be obtained, thus yielding the 3D image. The GDD acts as a heterodyne mixer not only electronically but also optically. The suggested 3D upconversion technique using the GDD is simple and inexpensive and has better performance compared to other MMW/THz imaging systems suggested in the literature. This method provides minimum detectable signal power that is about 6 orders of magnitude better than similar plasma systems due to the very large internal signal gain deriving from the much smaller electrode separation and resulting in much higher plasma electric field.

Performance Enhancement of Inexpensive Glow Discharge Detector Operating in Up-Conversion Mode in Millimeter Wave Detection for Focal Plane Arrays

“…In up-conversion detection (or optical detection), the electric field of the MMW/THz radiation causes a slight change in the electrical bias current, which increases the emitted light from the GDD [17]. This increase in the GDD light intensity derives from de-excitation or recombination rather than electron excitation.…”

“…The glow discharge detector (GDD) was found to be one of the typical MMW/THz radiation detectors [3,4,[6][7][8][9][10][11][12] and pixels in focal plane arrays [13][14][15][16][17][18] but is orders of magnitude less expensive compared to other known MMW/THz sensors [1]. This is particularly important for detector arrays as in imaging.…”

“…A new detection mechanism for MMW/THz radiation detection using GDD, named up-conversion method, was suggested [17]. The up-conversion method (optical detection) refers to the detection of changes in the emitted light from the GDD due to incident MMW/THz radiation, rather than the changes in its electrical current (electronic detection).…”

“…In the up-conversion method, a basic photodiode or any basic light sensor is required in order to measure the changes in the GDD emitted light. The advantages of the upconversion method are: (1) a very fast response time which is limited by the light sensor response, (2) a lower internal noise compared to the electric detection [17], and (3) it is very inexpensive.…”

Beam reconfigurable holographic artificial impedance surface at terahertz band

“…On the other hand, the terahertz (THz) spectrum [38,39], ranging from 0.3 to 3 THz defined by thr international telecommunication union (ITU), has attracted recently attracte a great deal of attention [40][41][42][43][44]. Compared with the microwaves, THz wave features shorter wavelength, higher energy and higher spatial resolution, etc.…”