Lithium Niobate Vertical Cavity Electro-Optic Modulator

TL;DR

This paper presents a novel vertical-cavity lithium niobate electro-optic modulator that achieves efficient modulation with a simple fabrication process, suitable for compact optical applications like LiDAR and beam steering.

Contribution

It introduces a vertical-cavity LN EOM with integrated photonic crystal mirrors and electrodes, demonstrating high modulation depth and bandwidth in a scalable, free-space compatible platform.

Findings

43% transmission depth at 50 V

Bandwidth of 5 MHz

Compatible with free-space optical systems

Abstract

Electro-optic modulators (EOMs) are vital for optical imaging and information processing, with free-space devices enabling LiDAR and beam control. Lithium niobate (LN), powered by the strong Pockels effect and scalable LN-on-insulator (LNOI) platform, has become a leading material for high-performance EOMs. Here we realize a vertical-cavity EOM in which an LN membrane is sandwiched between two photonic crystal (PhC) mirrors with integrated electrodes. The cavity supports sharp defect-mode resonances that shift efficiently under the Pockels effect, enabling strong modulation of transmission. Experiments show a depth of 43 % at 50 V and a bandwidth of 5 MHz. This architecture combines free-space compatibility with fabrication simplicity, opening new routes to compact electro-optic platforms for ranging, holography, and beam steering.