Noncollinear matched broadband third-harmonic generation based on angular dispersion

Broadband laser can effectively reduce the nonlinear effect in the process of laser plasma interaction. This paper proposes a noncollinear matching broadband third-harmonic generation based on angular dispersion, which uses the noncollinear sum frequency of the broadband fundamental wave and the narrowband second harmonic to generate broadband third harmonic, and the sum frequency process is realized by a specially designed gradient grating. The fundamental laser beams of different frequencies are incident at a specific angle, which compensates for the phase mismatch caused by the wavelength difference, so that the whole waveband meets the match condition of phase. Theoretical simulation shows that using KDP crystal type II phase matching, high efficiency broadband third-harmonic generation can be achieved by combining the broad-band fundamental wave (center wavelength 1058 nm, bandwidth 10 nm) and the second harmonic (526.5 nm).