Generation of 210 GW few-cycle ultraviolet laser pulses

We demonstrate generation, spectral broadening, and post-compression of ultraviolet pulses using a thin BBO crystal on a fused silica substrate as the nonlinear interaction medium. By combining the second harmonic generation in the BBO crystal with self-phase modulation in the fused silica substrate, we efficiently generated broadband ultraviolet pulses and subsequently compress the pulses to a duration of 5 fs, achieving a peak power of 210 GW. The all-solid free-space apparatus is compact and robust, and can be scaled for higher powers, making it highly advantageous for generating intense ultraviolet pulses in the few-cycle regime. Furthermore, our method can be applied generally to achieve spectral broadening and pulse compression of ultraviolet and visible pulses through the utilization of thin nonlinear media for harmonic generation and self-phase modulation. Our work presents a significant step forward in the generation of high-power, broadband, ultrashort ultraviolet pulses, and opens up exciting possibilities for future research and applications in the realm of nonlinear physics and ultrafast science