Bandwidth scaling of near-infrared enhancement cavities

Passive optical resonators are important tools for enhancing the sensitivity of spectroscopic measurements [1], and for enhancing the peak and average power of femtosecond laser pulses to the levels necessary for high-order harmonic generation (HHG), e.g. for the generation of XUV frequency combs [2]. The optical bandwidth and thus the pulse duration in such enhancement cavities (ECs) is typically hmited by the spectral phase curvature inherent to the highly reflective multilayer mirrors.