A stable 2 W continuous-wave 261.5 nm laser for cooling and trapping aluminum monochloride

TL;DR

This paper reports a high-power, stable 261.5 nm laser using cavity-enhanced doubling stages, enabling advanced spectroscopy and potential laser cooling of aluminum monochloride molecules.

Contribution

It introduces a novel high-power DUV laser system with watt-level stability, suitable for molecular spectroscopy and laser cooling applications.

Findings

Generated up to 2.75 W of 261.5 nm light with stable output.

Performed fluorescence spectroscopy on AlCl molecules.

Probed hyperfine structure for future cooling and trapping.

Abstract

We present a high-power tunable deep-ultraviolet (DUV) laser that uses two consecutive cavity enhanced doubling stages with LBO and CLBO crystals to produce the fourth harmonic of an amplified homebuilt external cavity diode laser. The system generates up to 2.75 W of 261.5 nm laser light with a ~2 W stable steady-state output power and performs second harmonic generation in a largely unexplored high intensity regime in CLBO for continuous wave DUV light. We use this laser to perform fluorescence spectroscopy on the $X^1\Sigma\leftarrow A^1\Pi$ transition in a cold, slow beam of AlCl molecules and probe the $A^{1} \Pi|v'=0,~J'=1>$ state hyperfine structure for future laser cooling and trapping experiments. This work demonstrates that the production of tunable, watt-level DUV lasers is becoming routine for a variety of wavelength-specific applications in atomic, molecular and optical physics.