A single-mode external cavity diode laser using an intra-cavity atomic Faraday filter with short-term linewidth $<400$ kHz and long-term stability of $<1$ MHz

TL;DR

This paper introduces a 'Faraday laser' that uses an atomic Faraday filter for stable, single-frequency diode laser operation with linewidth and stability better than 1 MHz, simplifying laser setup for atomic physics applications.

Contribution

The paper presents a novel diode laser system employing an atomic Faraday filter for inherent frequency stability without complex control systems.

Findings

Short-term linewidth <400 kHz

Long-term stability <1 MHz

Suitable for laser cooling experiments

Abstract

We report on the development of a diode laser system - the `Faraday laser' - using an atomic Faraday filter as the frequency-selective element. In contrast to typical external-cavity diode laser systems which offer tunable output frequency but require additional control systems in order to achieve a stable output frequency, our system only lases at a single frequency, set by the peak transmission frequency of the internal atomic Farady filter. Our system has both short-term and long-term stability of less than 1~MHz, which is less than the natural linewidth of alkali-atomic D-lines, making similar systems suitable for use as a `turn-key' solution for laser cooling experiments.