High-power exclusively type 1 sum-frequency generation of 257-nm radiation in LBO crystals

We present a frequency conversion setup using three type I phase-matched LBO crystals for the generation of high-power deep ultraviolet (DUV) radiation by frequency conversion of pulsed infrared laser radiation. The presented approach allows more independent control of the three individual conversion processes compared to LBO-based approaches presented to date. An average output power of 33 W at a wavelength of 257 nm was demonstrated. The duration of the DUV pulses was 3.4 ps, the pulse repetition rate was 400 kHz, and the beam propagation factor was measured to be M 2 = 1.99 at the highest power.