High-power, frequency-quadrupled UV laser source resonant with the 1S0-3P1 narrow intercombination transition of cadmium at 326.2 nm

We present a novel high-power, frequency-stabilized UV laser source at 326.2 nm, resonant with the Cd S-1(0)-P-3(1) narrow intercombination transition. We achieve a maximum produced power of 1 W at 326.2 nm by two successive frequency doubling stages of a narrow-linewidth (<1 kHz) seed laser at 1304.8 nm. Approximately 3.4 W of optical power at 652.4 nm is produced by a visible Raman fiber amplifier (VRFA) that amplifies and generates the second harmonic of the infrared radiation. The visible light is subsequently frequency-doubled down to 326.2 nm in a nonlinear bow-tie cavity using a Brewster-cut beta-barium-borate (BBO) crystal, with a maximum conversion efficiency of approximately 40% for 2.5 W of coupled red power. Full characterization of the laser source, together with spectroscopy signals of all Cd isotopes, spanning more than 4 GHz in the UV, are shown. (C) 2022 Optica Publishing Group