All-solid-state far-UVC pulse laser at 222 nm wavelength for UVC disinfection

Abstract

A 222 nm all-solid-state far-ultraviolet C (UVC) pulse laser system based on an optical parametric oscillator (OPO) and second-harmonic generation (SHG) using β-Ba 2 BO 4 (BBO) crystals was demonstrated. Pumped by a Nd∶Y 3 Al 5 O 12 laser with a repetition rate of 100 Hz at 355 nm, the maximum signal laser pulse energy of 1.22 mJ at 444 nm wavelength was obtained from the BBO-OPO system, corresponding to a conversion efficiency of 27.9%. The maximum output pulse energy of 164.9 μJ at the 222 nm wavelength was successfully achieved, corresponding to an SHG conversion efficiency of 16.2%. Moreover, the tunable output wavelength of UVC light from 210 nm to 252.5 nm was achieved.

Continuous-wave second-harmonic generation in the far-UVC pumped by a blue laser diode

“…Another approach for frequency conversion to the far-UVC involves a pulsed pump source for optical parametric oscillation and SHG. Demonstrations achieved 16.2 % efficiency from a 1.2 mJ pump, generating pulses at 222 nm wavelength 36 . Compressed pulses were also used in He-filled hollow capillary fibers, achieving 3.6 % conversion from 0.2 mJ pulses 37 .…”