Monolithic integration of a high-quality factor lithium niobate microresonator with a free-standing membrane waveguide using femtosecond laser assisted ion beam writing (FLAIBW)

TL;DR

This paper presents a novel femtosecond laser and ion beam technique for monolithically integrating high-Q lithium niobate microresonators with membrane waveguides, enabling efficient light coupling.

Contribution

It introduces a combined femtosecond laser and focused ion beam method for high-quality monolithic integration of lithium niobate photonic structures.

Findings

Achieved a microresonator quality factor of 1.67×10^5

Demonstrated efficient light coupling between waveguide and microdisk

Reduced surface roughness to nanometer scale

Abstract

We demonstrate integrating a high quality factor lithium niobate microdisk resonator with a free-standing membrane waveguide. Our technique is based on femtosecond laser direct writing which produces the pre-structure, followed by focused ion beam milling which reduces the surface roughness of sidewall of the fabricated structure to nanometer scale. Efficient light coupling between the integrated waveguide and microdisk was achieved, and the quality factor of the microresonator was measured as high as 1.67*10^5.