Microwave Electromagnetic Field Sensor on Thin-Film Lithium Niobate Using Photonic Down-Conversion Detection

We integrate a bow-tie antenna on thin-film lithium niobate (TFLN) phase modulator to form an electromagnetic E-field sensor. The fiber-coupled TFLN chip is probed by two-tone optical local oscillator generated using external modulator, which after appropriate filtering allows the system act as photonic down-converter. compatible with use of balanced detection, enabling improved signal-to-noise ratio. demonstrate down-conversion 28.3 GHz free-space microwave signal 100 MHz sensitivity 2 mV/m/√Hz. current limitation stems from relatively high (25 dB) insertion loss packaged device, not inherent design. technology can be directly scaled much higher frequencies and attractive for remote detection signals.