# Realization of High-Power Single-Frequency Continuous-Wave Tunable 689 nm Laser

## TL;DR

Researchers developed a high-power, tunable 689 nm laser using a titanium-sapphire crystal, achieving efficient output and demonstrating its use for strontium atom absorption.

## Contribution

A high-efficiency, single-frequency, tunable 689 nm laser was developed with precise thermal control and demonstrated for atomic applications.

## Key findings

- A 3.65 W single-frequency continuous-wave 689 nm laser was achieved with 23.1% optical-to-optical conversion efficiency.
- A 17 GHz continuous-frequency tuning range around 689 nm was realized using a PZT-mounted cavity mirror.
- The laser was used to obtain absorption spectra of strontium atoms, showing potential for atomic ensemble applications.

## Abstract

By analyzing the influence of the titanium–sapphire (Ti:S) crystal thermal effect on the laser resonator during the generation of a 689 nm laser, the thermal characteristics of the Ti:S crystal operating near the gain edge were investigated in this letter. On this basis, a Ti:S laser with high conversion efficiency suitable for operation at the wavelength of 689 nm was designed. Benefiting from the quantification of thermal effects, the beam waist size at the center of the Ti:S crystal was precisely controlled. Finally, a single-frequency continuous-wave 689 nm laser with an output power of 3.65 W was achieved, and the corresponding optical-to-optical conversion efficiency was up to 23.1%. Then, after locking the transmission peak of the inserted etalon to the resonance frequency of the resonator, the continuous-frequency tuning range of 17 GHz around 689 nm was realized by scanning the voltage applied to the piezoelectric transducer (PZT) mounted on the cavity mirror. Furthermore, based on the realized single-frequency continuous-wave tunable 689 nm laser source, the absorption spectra of strontium atoms near 689 nm were obtained, which established a promising method for preparing 689 nm laser sources designed for strontium atomic ensembles.