Megawatt peak power, 1 kHz, 266 nm sub nanosecond laser source based on single-crystal fiber amplifier

Summary form only given. The development of solid state UV lasers is major industrial challenge for various applications, among them spectroscopy, lithography, material processing, or ophthalmology.In this paper, we present a 266 nm UV source based on the fourth harmonic generation of a Nd:YAG single-crystal fiber MOPA previously developed [4]. The 1064 nm amplified laser system is described in detail in [5]. A Q-switched microchip laser is amplified with a Nd:YAG singlecrystal fiber in double pass configuration. It delivers a maximum of 2.3 W at 1 kHz with pulses of 550 ps (2.3 mJ pulses) and an excellent beam quality (M2=1.06), reaching a peak power of more than 4 MW. The frequency conversion scheme (Fig.1) is based on harmonic generation LBO/BBO crystals. We reached 22.7% of total conversion efficiency from infrared to UV. We obtained a 266 nm output of 530 mW (Fig.2), at 1 kHz with pulses width of 540 ps. This represents a peak power of 980 kW. We measured the UV beam profile and determine its M2 to be <;2. To the best of our knowledge, this is the first realization of a 266 nm sub nanosecond source based on passively Q-switched oscillator with MW peak power combined with half-watt average power. This work demonstrates the potential of single-crystal fiber amplifiers for high performance UV MOPA systems