Abstract
Abstract In this study, a high-energy, temporally shaped picosecond ultraviolet (UV) laser running at 100 Hz is demonstrated, with its pulses boosted to 120 mJ by cascaded regenerative and double-pass amplifiers, resulting in a gain of more than 108. With precise manipulation and optimization, the amplified laser pulses were flat-top in the temporal and spatial domains to maintain high filling factors, which significantly improved the conversion efficiency of the subsequent third harmonic generation (THG). Finally, 91 mJ, 470 ps pulses were obtained at 355 nm, corresponding to a conversion efficiency as high as 76%, which, as far as we are aware of, is the highest THG efficiency for a high-repetition-rate picosecond laser. In addition, the energy stability of the UV laser is better than 1.07% (root mean square), which makes this laser an attractive source for a variety of fields including laser conditioning and micro-fabrication.
Highlights
High-power ultraviolet (UV) lasers are desirable for many applications, including laser conditioning, micro-nano fabrication, laser-propelled space debris removal, quantum optics, and nonlinear optical measurement[1,2,3,4,5,6,7,8]
After passing through a fiber isolator, the seed laser beam is collimated by an aspheric lens and passes through an optical isolator, which is composed of a polarization beam splitter (PBS), Faraday rotator (FR), and half-wave plate (HWP)
Owing to the gain saturation effect of the Nd:YAG amplifier, the temporal width of the laser pulses was shortened after passing the main amplifier (MA); because of temporal distortion during the amplification process, the temporal power density of the front edge was higher than that of the back edge of the output laser pulses, which resulted in a low filling factor and low third harmonic generation (THG) conversion efficiency
Summary
High-power ultraviolet (UV) lasers are desirable for many applications, including laser conditioning, micro-nano fabrication, laser-propelled space debris removal, quantum optics, and nonlinear optical measurement[1,2,3,4,5,6,7,8]. Owing to limitations in the emission spectra of gain crystals, high-power UV lasers are usually obtained by third harmonic generation (THG) from near-infrared lasers. THG is a technique of nonlinear crystal-based sum frequency generation (SFG) between the fundamental and second harmonic frequencies; a consequence of two cascaded nonlinear processes is a low total conversion efficiency. In 2013, 12 ps, 39.1 W, 355 nm laser pulses were obtained using a multipass slab amplifier and LiB3O5 (LBO) crystals, which had a THG efficiency of 46%[10]. In 2015, 8 ps, 234 W, 343 nm laser pulses were generated by a 300 kHz Yb:YAG thindisk laser and two LBO crystals with a THG conversion efficiency of 32%[11]. In 2016, 37 ps, 30.9 W, 300 kHz laser pulses at 355 nm were obtained using CsLiB6O10 with a THG conversion efficiency of approximately 48%[12]. It is desirable to develop a precise spatiotemporal manipulation technique to improve the filling factor
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
