Thin-film lithium niobate integrated photonics at 493 nm

Abstract

Visible and near-ultraviolet light underpins applications from biophotonics to quantum computing, which demand fast control of optical amplitude and phase. Integrated photonics offers scalable control, yet most visible-wavelength platforms lack gigahertz-scale modulation. We demonstrate a thin-film lithium niobate platform at 493 nm integrating grating couplers, beamsplitters, ring resonators, and modulators. Segmented traveling-wave modulators achieve a half-wave voltage--length product of 450 mV$\cdot$cm, $>$20 dB extinction, and bandwidth beyond 50 GHz. Ring resonators show $2.9\pm 0.2$ dB/cm propagation loss and quantify the platform's photorefractive response. This enables agile visible beam delivery for trapped-ion systems, although photorefraction and substrate uniformity remain key challenges to scaling.