Thin film lithium niobate electric field sensors

Abstract

We present our results for using thin film lithium niobate devices for electric field sensing applications. Micro-ring modulator and Mach–Zehnder modulator-based electric field sensors are demonstrated. Micro-ring resonator sensors can be used for low frequency (up to several GHz) electric field sensing applications and achieve a high sensitivity of 80 mV/(m Hz1/2) with a very compact size of 300  μm, as limited by the intensity and phase noise of the used distributed feedback laser. A measurement bandwidth of 2.5 GHz is measured for these sensors and is limited by the detector bandwidth. Alternatively, Mach–Zehnder modulators allow for perfect phase matching between the radio frequency signals and optical signals, and they can be used for electric field sensing up to several THz. A sensitivity of 2.2 V/(m Hz1/2) was obtained using our Mach–Zehnder electric field sensor with an interaction length of 600  μm. The Mach–Zehnder sensor can sense electric fields with frequencies reaching 0.6 THz based on the calculated results.