Extreme Nonlinear Optics in a Femtosecond Enhancement Cavity

TL;DR

This paper investigates the complex nonlinear optical effects occurring in femtosecond enhancement cavities during high-order harmonic generation, focusing on plasma-induced distortions and their impact on power scaling and frequency comb stability.

Contribution

It provides both experimental and theoretical insights into plasma-related nonlinearities in high-finesse cavities, advancing understanding of their effects on harmonic generation and frequency combs.

Findings

Identification of optical bistability caused by plasma effects

Analysis of self-phase modulation within the cavity

Implications for power scaling of high-order harmonic generation

Abstract

Intrinsic to the process of high-order harmonic generation is the creation of plasma and the resulting spatiotemporal distortions of the driving laser pulse. Inside a high finesse cavity where the driver pulse and gas medium are reused, this can lead to optical bistability of the cavity-plasma system, accumulated self-phase modulation of the intracavity pulse, and coupling to higher order cavity modes. We present an experimental and theoretical study of these effects and discuss their implications for power scaling of intracavity high-order harmonic generation and extreme ultraviolet frequency combs.