Self-induced Faraday instability laser

TL;DR

This paper predicts a novel self-induced Faraday instability in lasers caused by pump depletion, leading to ultrahigh repetition rate pulse trains even in normal dispersion regimes, with applications demonstrated in Raman fiber lasers.

Contribution

It introduces the concept of self-induced Faraday instability in lasers, a phenomenon not previously described, and provides a theoretical and numerical analysis of its mechanisms and applications.

Findings

Instability causes continuous wave to pulse train transition

Ultrahigh repetition rate pulses generated in normal dispersion regime

Good agreement between analysis and numerical modeling

Abstract

We predict the onset of self-induced parametric or Faraday instabilities in a laser, spontaneously induced by the presence of pump depletion in the cavity, which leads to a periodic gain landscape for light propagating in the cavity. As a result of the instability, continuous wave oscillation becomes unstable even in the normal dispersion regime of the cavity, and a periodic train of pulses with ultrahigh repetition rate is generated. Application to the case of Raman fiber lasers is described, in good quantitative agreement between our conceptual analysis and numerical modeling.