Design, fabrication, and characterization of LiNbO3 optical modulator for high-sensitivity mmW imaging system

Recently, our group has developed a high-sensitivity millimeter-wave (mmW) imaging system based on optical upconversion. In such a system, native mmW radiation of objects is first collected by a broadband horn antenna, which feed the mmW signal to Co-Planar Waveguide (CPW) on a Lithium Niobate(LN) Electro Optical (EO) modulator. The mmW power is then transferred to the sidebands of an optical carrier due to phase modulation. Detection is realized by measuring the optical power transferred to the sidebands. The overall performance of the imaging system is highly dependent on the conversion efficiency of the EO modulator, which is a function of the frequency of the collected millimeter-wave energy. In this paper, we present the design, fabrication and experimental results towards realizing LN EO modulators for use in the 95 GHz imaging band.