Fig. 1. Schematic of the broadband OPA at degeneracy（SHG: second harmonic generation）

Fig. 2. Two types of non-collinear phase matching in BBO crystal

Fig. 3. Phase matching curves for degenerate OPA and SHG in BBO crystal with type I phase matching

Fig. 4. Incident seed spectrum for the ps-OPCPA front-end of the SLIEX-II laser facility, and optical parametric amplified spectrum

Fig. 5. Temporal waveforms and spectra of the initial pump and signal

Fig. 6. Output performance of degenerate optical parametric amplification ignoring the second harmonic parasitic effects of signal and idler

Fig. 7. Impact of second harmonic parasitic effects on degenerate optical parametric amplification with walk-off compensation

Fig. 8. Impact of second harmonic parasitic effects on degenerate optical parametric amplification with non-walk-off compensation

Fig. 9. Effects of various pump spectral bandwidths on signal output spectrum, signal output flux and signal spectral width