Self-injection-locked second-harmonic integrated source

TL;DR

This paper demonstrates a compact, chip-scale high-coherence visible light source using self-injection-locking within a nonlinear resonator, enabling scalable, efficient, and low-cost integrated laser systems for advanced sensing and navigation.

Contribution

It introduces a novel integrated approach combining wavelength conversion and coherence enhancement via self-injection-locking in a single nonlinear resonator, scalable with mature III-V and lithium niobate technologies.

Findings

Achieved short-term linewidth of 10-30 kHz.

On-chip converted optical power exceeds 2 mW.

Conversion efficiency over 25% with output power over 11 mW.

Abstract

High coherence visible and near-visible laser sources are centrally important to the operation of advanced position/navigation/timing systems as well as classical/quantum sensing systems. However, the complexity and size of these bench-top lasers is an impediment to their transitioning beyond the laboratory. Here, a system-on-a-chip that emits high-coherence visible and near-visible lightwaves is demonstrated. The devices rely upon a new approach wherein wavelength conversion and coherence increase by self-injection-locking are combined within in a single nonlinear resonator. This simplified approach is demonstrated in a hybridly-integrated device and provides a short-term linewidth around 10-30 kHz. On-chip, converted optical power over 2 mW is also obtained. Moreover, measurements show that heterogeneous integration can result in conversion efficiency higher than 25% with output power over 11 mW. Because the approach uses mature III-V pump lasers in combination with thin-film lithium niobate, it can be scaled for low-cost manufacturing of high-coherence visible emitters. Also, the coherence generation process can be transferred to other frequency conversion processes including optical parametric oscillation, sum/difference frequency generation, and third-harmonic generation.