In recent years, the development of new lithium niobate electro-optic modulator designs and material processing techniques have contributed to support the increasing need for faster optical networks by considerably extending the operational bandwidth of modulators. In an effort to provide higher bandwidths for future generations of networks, we have developed a lithium niobate electro-optic phase modulator based on a coplanar waveguide ridged structure that operates up to 300 GHz. By thinning the lithium niobate substrate down to less than 39 µm, we are able to eliminate substrate modes and observe optical sidebands over the full millimeter-wave spectrum.
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.
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