Widely tunable, narrow linewidth external-cavity gain chip laser for spectroscopy between 1.0 - 1.1 um

TL;DR

This paper presents a stable, tunable, narrow linewidth external-cavity laser operating between 1.0 and 1.1 micrometers, suitable for spectroscopy, with demonstrated applications in metastable helium spectroscopy and promising stability and tuning capabilities.

Contribution

The authors develop a cost-effective, high-performance external-cavity laser with wide tunability and narrow linewidth, advancing laser sources in the 1.0-1.1 micrometer range.

Findings

Tunable over 100 nm around 1080 nm with 30 pm continuous tuning

Spectral linewidth of 22 kHz (Gaussian) and 4.2 kHz (Lorentzian)

Long-term frequency stability better than 40 kHz over 11 hours

Abstract

We have developed and characterised a stable, narrow linewidth external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a single-angled-facet gain chip. We propose the ECL as a low-cost, high-performance alternative to fibre and diode lasers in this wavelength range and demonstrate its capability through the spectroscopy of metastable helium. Within the coarse tuning range, the wavelength can be continuously tuned over 30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz (piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5 ms, while a long-term frequency stability better than 40(20) kHz over 11 hours was observed when locked to an atomic reference.