Fig. 1. Overall working scheme of beam stabilization system, spectral broadening system, and pulse duration compression system

Fig. 2. Comparison of driving laser spectra before and after the broadening and the pulse duration before and after compression. (a) Optical spectra of laser system before and after broadening by the solid-core PCF; (b) temporal pulse shapes measured by FROG for original pulses from laser system and compressed pulse

Fig. 3. Schematic of fsEC

Fig. 4. Evolutionary of laser transverse mode near the focal point and throughout the fsEC. (a) Variation on the size of cavity focal spot in the horizontal direction with the separation of concave mirrors; (b) sizes of the beam at various positions within the fsEC based on theoretical calculations (line) and experimental measurements (triangle) when the separation of concave mirrors is about 12.6 cm

Fig. 5. Fluorescence images when Xe, Kr, and Ar are used as the gas medium, respectively. (a)-(c) Fluorescence images on a sodium salicylate plate generated by high-order harmonics; (d)-(f) pictures of the plasma and the fluorescence radiation at the nozzle

Fig. 6. Generated optical frequency comb when Xe is used as the gas medium. (a) Image of the harmonics from Xe fluorescing on a sodium salicylate plate out-coupled by the GM; (b) spectrum of out-coupled harmonic radiation obtained from the images of the fluorescent plate, and the black dot lines indicate the power of each harmonic