Fig. 1. (a) Schematic of the laser system. PS: actuator; L: lens; BS: beam splitter; LS: linear stage; W: CaF₂ window; CM: concave mirror; DM: dichroic mirror; BT: beam trap; WP: wedge pair. (b) The output beam profile of the HCF and (c) the near-field and (d) far-field beam profiles of the 910 nm beam.

Fig. 2. (a) Spectrum profiles measured by a near-infrared spectrometer at different argon pressures; (b) energy stability of the output laser after the HCF system.

Fig. 3. The SHG spectra with one single crystal and cascaded crystals.

Fig. 4. (a) Spectra and spectral phase of the 910 nm laser: spectrum (pink filled) with a fiber spectrometer, spectrum (red solid) with a Wizzler device, measured spectral phase (black solid) and retrieved spectral phase (black dot). (b) Measured (golden filled) and FTL (red solid) pulse duration of the 910 nm pulse.

Fig. 5. (a) Energy stability of the 910 nm laser; (b) spectrum stability of the 910 nm laser.

Fig. 6. (a) Third-order correlation curves of the initial pulse (black) and the 910 nm pulse (red); (b) third-order correlation curve of the laser pulse after a one-stage OPCPA system.