# Broadband lasers for photo-ionization and repumping of trapped ions

## TL;DR

This paper introduces a broadband, frequency-stable laser based on semiconductor optical amplifiers for trapped ion experiments, enabling efficient photo-ionization without complex stabilization.

## Contribution

The work demonstrates a widely tunable, broadband laser source using semiconductor technology suitable for various wavelengths and capable of efficient second harmonic generation.

## Key findings

- Achieved a 10 GHz linewidth at 921.7 nm
- Generated 20 mW output power at 921.7 nm
- Demonstrated efficient frequency doubling to 460.9 nm

## Abstract

A frequency-stable, broadband laser is presented for experiments on trapped ions. Since the design is based on widely available semiconductor optical amplifier technology, similar lasers can be realized for virtually any wavelength in the near-infrared, and the coherence properties and output power allow for efficient second harmonic generation. No closed-loop frequency stabilization for addressing Doppler- or naturally-broadened, dipole-allowed transitions is needed, and the light source can be turned on and off during a measurement cycle with sub-microsecond response time. As a case study, a 921.7-nm laser with an output power of 20mW and a linewidth of 10GHz is realized, which is then frequency doubled to 460.9nm for excitation of strontium as the first step in photo-ionization. The excitation efficiency is compared to that achievable with a narrow-linewidth distributed Bragg reflector laser as well as to theory.