Cavity-enhanced harmonic generation of an optical frequency comb with Laguerre–Gaussian mode

Tailoring the resonant transverse mode of a femtosecond enhancement cavity (fsEC) is of vital importance in manipulating light-matter interaction in a laser cavity. In this study, the transverse mode of a driving near-infrared optical frequency comb is tailored from a Hermite-Gaussian (HG) mode to a Laguerre-Gaussian (LG) mode, and then amplified to a kilowatt level in an fsEC for the first time, to our knowledge. Through the harmonic generation process with Xe gas, a bright plasma is observed, and the third harmonic is measured to be 29 <i>μ</i>W. Our study will stimulate the development of ultraviolet/vacuum ultraviolet (UV/VUV) combs with LG transverse modes.