High-sensitivity monolithic photonic electric-field probe for 40-110 GHz operation

Conventional electric-field probes for V- and W-band measurements are limited by field perturbation, bulky metallic front ends, and insufficient instantaneous bandwidth. We report a high-sensitivity monolithic photonic electric-field probe on a thin-film lithium niobate (TFLN)-on-quartz platform for 40-110 GHz operation. The device combines an asymmetric Mach-Zehnder interferometer (AMZI)-based sensing architecture with an inverse-designed compact antenna of only 2×1.8 mm² and a traveling-wave electro-optic interaction region with terminal matching. The inverse-designed compact antenna enables efficient broadband field reception with a relatively flat response across 40-110 GHz within a limited chip area, while the AMZI-based architecture, together with the TFLN-on-quartz platform and impedance-matched traveling-wave interaction, supports high-sensitivity electric-field readout. Broadband electric-field probing is experimentally demonstrated from 40 to 110 GHz, with normalized sensitivity better than 6 mV/m/Hz^1/2 across the full band and a best value of 1.2 mV/m/Hz^1/2. These results establish a monolithic photonic approach to broadband high-sensitivity electric-field probing over the full V- and W-band.