Chip-integrated extended-cavity mode-locked laser in the visible

TL;DR

This paper reports the first chip-integrated visible mode-locked laser using a gallium arsenide gain chip and silicon nitride circuit, achieving stable pulsed operation at 642 nm for applications in imaging and quantum technologies.

Contribution

It introduces a novel integrated photonic circuit for cavity extension enabling visible mode-locking on a chip, overcoming previous challenges in the visible spectrum.

Findings

Operates at 642 nm with 3.4 mW output power

Achieves 7.84 GHz repetition rate

Spectral bandwidth of 1.5 nm

Abstract

Mode-locked lasers are of interest for applications such as biological imaging, non-linear frequency conversion, and single-photon generation. In the infrared, chip-integrated mode-locked lasers have been demonstrated through integration of laser diodes with low-loss photonic circuits. However additional challenges, such as a higher propagation loss and smaller alignment tolerances have prevented the realization of such lasers in the visible range. Here, we demonstrate the first chip-integrated mode-locked diode laser in the visible using an integrated photonic circuit for cavity extension. Based on a gallium arsenide gain chip and a low-loss silicon nitride feedback circuit, the laser is passively mode-locked using a saturable absorber implemented by focused ion beam milling. At a center wavelength of 642 nm, the laser shows an average output power of 3.4 mW, with a spectral bandwidth of 1.5 nm at a repetition rate of 7.84 GHz.