Development of a high-speed modulator for a W-band millimetre-wave imaging system

Abstract

Millimetre-wave (mmW) imaging has attracted significant research interests for the promises of allweather imaging and security scanning for military applications. Recently, we have developed a highsensitivity mmW imaging system based on photonic devices, which relies on optical up-conversion of the received mmW signal to generate detectable sidebands. For system with lower detector reponsivity, higher resolution and wider separation between sidebands and optical carrier, a high efficiency EO modulator that works in W-band is required. Since such system does not exist commercially, we were motivated to develop our own 94GHz phase modulator. In our previous publications, we have presented design, fabrication and preliminary characterization of Lithium Niobate (LN) based devices. We continue in this paper with our post-processing techniques, updated characterization results and the packaging method between antenna and modulator. Modulation efficiency >1W -1 has been achieved over W-band. Using a fin-coupler for antenna integration, we have obtained insertion loss less than 3dB. The packaged modulator has been installed in our imager. Initial scanning showed high-quality images of various objects.

Outdoor Passive Millimeter-Wave Imaging: Phenomenology and Scene Simulation

“…The maritime environment is characterized generally by a high relative humidity, particularly in the evaporation duct, a layer approximately up to 20 m thick above the sea surface. [54], metal pilings (top right) [54], a rubber boat (lower left) [53], and a fiber glass boat (lower right) [52]. Black denotes radiometrically 'hot.…”

“…Some spectacular imagery at 94 GHz of fiberglass and rubber boats from [52] and [53] and a metal boat from [54] are shown in Fig. 4.…”