# Octave spanning operation of visible to SWIR integrated coil-stabilized Brillouin lasers

## TL;DR

This paper introduces a compact, integrated laser system that achieves ultra-low noise and high stability across a wide range of wavelengths for precision applications.

## Contribution

The work presents the first integrated coil-resonator-stabilized Brillouin laser with over an octave span and record-low linewidths.

## Key findings

- The laser operates at 674, 698, and 1550 nm with fundamental linewidths of 1.0–17 Hz.
- Allan deviations of 6.5 × 10−13 at 1 ms and 2.6 × 10−13 at 15 ms were achieved.
- The system shows over an order of magnitude improvement in visible wavelength stability.

## Abstract

Narrow linewidth stabilized lasers are central to precision applications that operate across the visible to short-wave infrared wavelengths, including optical clocks, quantum sensing and computing, ultra-low noise microwave generation, and fiber sensing. Today, these spectrally pure sources are realized using multiple external cavity tabletop lasers locked to bulk-optic free-space reference cavities. Integration of this technology will enable portable precision applications with improved reliability and robustness. Here, we report wavelength-flexible design and operation, over more than an octave span, of an integrated coil-resonator-stabilized Brillouin laser architecture. Leveraging a versatile two-stage noise reduction approach, we achieve low linewidths and high stability with chip-scale laser designs based on the ultra-low-loss, CMOS-compatible silicon nitride platform. We report operation at 674 and 698 nm for applications to strontium neutral and trapped-ion clocks, quantum sensing and computing, and at 1550 nm for applications to fiber sensing and ultra-low phase noise microwave generation. Over this range we demonstrate frequency noise reduction from 1 to 10 MHz resulting in 1.0–17 Hz fundamental and 181–630 Hz integral linewidths and an Allan deviation of 6.5 × 10−13 at 1 ms for 674 nm, 6.0 × 10−13 at 15 ms for 698 nm, and 2.6 × 10−13 at 15 ms for 1550 nm. This work demonstrates the lowest fundamental and integral linewidths and highest stability achieved to date for stabilized Brillouin lasers with integrated coil-resonator references, with over an order of magnitude improvement in the visible wavelength range. These results unlock the potential of integrated, ultra-low-phase-noise stabilized lasers for precision applications and further integration in systems-on-chip solutions.