High-index-contrast single-mode optical waveguides fabricated on lithium niobate by photolithography assisted chemo-mechanical etching (PLACE)

TL;DR

This paper introduces a novel fabrication method called PLACE for creating low-loss, high-index-contrast single-mode waveguides on lithium niobate on insulator, achieving efficient light propagation and coupling.

Contribution

The paper presents a new femtosecond laser micromachining-based chemo-mechanical etching technique for fabricating high-quality waveguides on lithium niobate.

Findings

Propagation loss of 0.13 dB/cm for the waveguides

Successful fabrication of waveguide tapers for improved coupling

High-index-contrast single-mode waveguides achieved

Abstract

We report fabrication of low loss single mode waveguides on lithium niobate on insulator (LNOI) cladded by a layer of SiO2. Our technique, termed photolithography assisted chemo-mechanical etching (PLACE), relies on patterning of a chromium film into the mask shape by femtosecond laser micromachining and subsequent chemo-mechanical etching of the lithium niobate thin film. The high-index-contrast single mode waveguide is measured to have a propagation loss of 0.13 dB/cm. Furthermore, waveguide tapers are fabricated for boosting the coupling efficiency.