High-power and narrow-linewidth laser on thin-film lithium niobate enabled by photonic wire bonding

TL;DR

This paper demonstrates a high-power, narrow-linewidth on-chip laser on thin-film lithium niobate using photonic wire bonding, achieving significant power, stability, and tunability improvements for integrated photonic systems.

Contribution

It introduces a novel integration method with photonic wire bonding to realize high-power, narrow-linewidth lasers on TFLN, addressing a key bottleneck in the platform.

Findings

78 mW on-chip power achieved

Laser linewidth of 550 Hz measured

Mode-hop-free operation for 58 hours

Abstract

Thin-film lithium niobate (TFLN) has emerged as a promising platform for the realization of high performance chip-scale optical systems, spanning a range of applications from optical communications to microwave photonics. Such applications rely on the integration of multiple components onto a single platform. However, while many of these components have already been demonstrated on the TFLN platform, to date, a major bottleneck of the platform is the existence of a tunable, high-power, and narrow-linewidth on-chip laser. Here, we address this problem using photonic wire bonding to integrate optical amplifiers with a thin-film lithium niobate feedback circuit, and demonstrate an extended cavity diode laser yielding high on-chip power of 78 mW, side mode suppression larger than 60 dB and wide wavelength tunability over 43 nm. The laser frequency stability over short timescales shows an ultra-narrow intrinsic linewidth of 550 Hz. Long-term recordings indicate a high passive stability of the photonic wire bonded laser with 58 hours of mode-hop-free operation, with a trend in the frequency drift of only 4.4 MHz/h. This work verifies photonic wire bonding as a viable integration solution for high performance on-chip lasers, opening the path to system level upscaling and Watt-level output powers.