A single-mode external cavity diode laser using an intra-cavity atomic Faraday filter with short-term linewidth

James Keaveney,Ifan G Hughes,William J Hamlyn,Charles S Adams

doi:10.1063/1.4963230

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 Faraday 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.

Highlights

Diode laser systems have for a long time been the workhorse of atomic physics used in an extremely broad range of applications from laser cooling to thermal vapour experiments.1 In the usual case of an external cavity diode laser (ECDL), the external cavity is formed using a grating which results in a frequency-selective feedback, ensuring lasing on one dominant mode
We report on the development of a diode laser system - the “Faraday laser” - using an atomic Faraday filter as the frequency-selective element
The exact source of this noise is beyond the scope of the current investigation. We note that this is the combined linewidth of both laser systems—the measured linewidth is the convolution of the linewidth of each laser

Summary

Introduction

Diode laser systems have for a long time been the workhorse of atomic physics used in an extremely broad range of applications from laser cooling to thermal vapour experiments. In the usual case of an external cavity diode laser (ECDL), the external cavity is formed using a grating which results in a frequency-selective feedback, ensuring lasing on one dominant mode. Whilst the ease of use and reliability of diode laser systems are continually increasing, the need for locking necessitates the use of external optics adding cost, volume, and requiring users to have a high degree of expertise in order to operate such systems successfully. Such systems often still need frequent attention to maintain their stability

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Conclusion