High-power, frequency-quadrupled UV laser source resonant with the $^{1}$S$_{0}$-$^{3}$P$_{1}$ narrow intercombination transition of cadmium at 326.2 nm

TL;DR

This paper reports the development of a high-power, frequency-stabilized UV laser at 326.2 nm resonant with cadmium's narrow intercombination transition, achieved through successive frequency doubling stages and characterized with isotope spectroscopy.

Contribution

The paper introduces a novel high-power UV laser source at 326.2 nm with stabilized frequency, using a multi-stage frequency doubling process and detailed spectral characterization.

Findings

Maximum power of 1 W at 326.2 nm achieved

Conversion efficiency of around 40% in the second harmonic generation

Spectroscopy of all Cd isotopes over 4 GHz range demonstrated

Abstract

We present a novel high-power, frequency-stabilized UV laser source at 326.2~nm, resonant with the Cd $^{1}$S$_{0}$ - $^{3}$P$_{1}$ narrow intercombination transition. We have achieved 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. About 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 non-linear bow-tie cavity using a Brewster-cut beta-barium-borate (BBO) crystal, with a maximum conversion efficiency of around 40$\%$ for 2.5~W 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.