Frequency-modulated comb in a VECSEL

TL;DR

This paper demonstrates the existence of frequency-modulated combs in VECSELs, revealing new physics and potential for high-power, wavelength-flexible applications in optical frequency comb technology.

Contribution

It shows that frequency-modulated comb regimes can exist in VECSELs, expanding understanding and enabling new high-power, wavelength-tunable comb applications.

Findings

Frequency-modulated combs observed in VECSELs.

Coherent beatnote spectroscopy confirms comb regime.

Potential for high-power, wavelength-flexible comb sources.

Abstract

Optical frequency combs based on mode-locked lasers have revolutionized many areas of science and technology, such as precision metrology, optical frequency synthesis or telecommunications. In recent years, a particular kind of frequency comb has been observed in edge-emitting semiconductor lasers where the phase difference between longitudinal laser modes is fixed but not zero. This results in a linearly chirped output in the time domain with nearly constant intensity. Here, by using coherent beatnote spectroscopy, we show that such a comb regime can also exist in vertical-external-cavity surface-emitting lasers (VECSELs), as evidenced for a specific part of the laser spectrum. Our findings may not only lead to a better understanding of the physics of frequency-modulated combs but also enable comb applications with high optical power per comb line and flexible emission wavelengths.