Demonstration of Passive W-Band Millimeter Wave Imaging Using Optical Upconversion Detection Methodology with Applications

Abstract

Millimeter wave (mmW) imaging has enjoyed a measure of success due to the unique properties of imaging in this spectral region, some of which are still being discovered. For example, a key advantage of mmW imaging is the ability to penetrate through various atmospheric obscurants, including fog, dust, sand, and smoke, due to its longer wavelengths as compared to visible or infrared imaging. Various methods of imaging with mmW energy exist, such as direct detection, downconversion, and upconversion, where this manuscript focuses on the latter. Until now, passive imaging using an optical upconversion method was limited to Q-band frequencies due to the lack of commercially available parts, namely a sufficiently high frequency optical modulator. To overcome this limitation, a custom-built modulator using in-house fabrication facilities was realized to allow imaging within the W-band frequency range (75–110 GHz). Therefore, in this manuscript we report new results of passive imaging in the W-band frequency range using a unique optical upconversion technique, where the higher frequency operation allows for greater detail in the imagery thus collected.