Investigating second harmonic generation using space-time wave packets

Second-harmonic generation (SHG) for ultrashort pulses is limited by phase-matching in dispersive media. Linear angular dispersion can compensate for group-velocity mismatch. A new class of optical beams known as space-time wave packets (STWPs) can provide multiple-order dispersion compensation, raising the prospects of broadband SHG. Here we investigate through detailed simulations SHG using STWPs. We make use of STWPs centered at 800 nm with 10-nm bandwidth in 100-micron-long BBO nonlinear crystals. We find that the SHG produced is also an STWP at a center wavelength of 400 nm with bandwidth 5 nm. Moreover, an internal parameter of the STWP known as the spectral tilt angle, which determines its group velocity, is conserved in the SHG process.