Laser frequency offset locking scheme for high-field imaging of cold atoms

TL;DR

This paper introduces a simple, flexible laser frequency offset locking scheme using commercial RF electronics and a homemade RF filter, enabling high-field imaging of ultra-cold atoms with stable laser offsets.

Contribution

The novel use of a sharp amplitude response of a homemade RF filter provides an effective error signal for laser locking, achieving large offset ranges and low residual fluctuations.

Findings

Offset lock range up to 1.4 GHz

Residual beat-note fluctuations below 2 MHz

Locking stability over hundreds of seconds

Abstract

We present a simple and flexible frequency offset locking scheme developed for high-field imaging of ultra-cold atoms which relies on commercially available RF electronics only. The main new ingredient is the use of the sharp amplitude response of a home-made RF filter to provide an error signal for locking the lasers. We were able to offset lock two independent diode lasers within a capture range of 200 MHz, and with a tuning range of up to 1.4GHz. The beat-note residual fluctuations for offset locked lasers are below 2MHz for integration times of several hundreds of seconds.