Enhancement of the electro-optic modulation efficiency in lithium niobate whispering gallery mode microdisk modulators.

Recent developments in photonic integrated circuits require dense integration of electro-optic devices with minimal energy consumption on-chip. Thin-film lithium niobate on insulator (LNOI) has emerged as one of the most promising material platforms for photonic integration, owing to recent advances in scalable fabrication techniques, a high electro-optic coefficient, sub-picosecond response time, and a wide transparency window. In this paper, we demonstrate efficient electro-optic tuning of an x-cut LNOI microdisk resonator with integrated electrodes. The microdisk modulator device's cross-section exhibits voltage-length products down to 4.70 V ·cm in a non-push-pull configuration. We compare the voltage-length product associated with the enhanced whispering gallery mode cross-section of the microdisk modulator to that of the microring and the Mach-Zehnder modulators, implemented on the same platform.