Fiber-coupled external cavity DFB-laser

TL;DR

This paper presents a fiber-coupled external cavity DFB-laser with ultra-narrow linewidths, suitable for portable quantum applications, achieved through intra-cavity EOM and active feedback referencing a high finesse cavity.

Contribution

The authors developed a fully fiber-coupled external cavity DFB-laser with active feedback for ultra-narrow linewidths, demonstrating its use in laser cooling of ultracold calcium atoms.

Findings

Achieved low kHz linewidths using intra-cavity EOM and active feedback.

Successfully used the laser for laser cooling of ${}^{40}$Ca atoms.

Implemented a data-driven power spectrum equalization for spectral analysis.

Abstract

Narrow-linewidth, compact and robust laser systems are of high interest, especially with prospects for portable quantum metrological applications. We realized an external cavity DFB-laser incorporating an intra-cavity EOM in a fully fiber-coupled manner. Additional active feedback on the EOM, by referencing a high finesse cavity, enabled us to reach low kHz-linewidths. We analyzed the laser spectrum by means of delayed self-heterodyne measurements to reconstruct the power spectral density. This is achieved by utilizing a data-driven power spectrum equalization approach. The presented laser setup is successfully used to create an ultracold gas by laser cooling on a narrow atomic transition of ${}^{40}$Ca at 1978 nm.