Laser frequency locking with 46 GHz offset using an electro-optic modulator for magneto-optical trapping of francium atoms

TL;DR

This paper demonstrates a novel laser frequency offset locking technique using a waveguide electro-optic modulator with 10th-order sidebands, enabling stable 46 GHz frequency difference for magneto-optical trapping of francium atoms.

Contribution

The study introduces a new method for locking laser frequencies with a 46 GHz offset using a waveguide EOM and delayed self-homodyne detection, suitable for trapping francium atoms.

Findings

Achieved stable frequency offset locking at 46 GHz.

Confirmed frequency sweeping over 1 GHz while maintaining the offset.

Enabled resonance search for magneto-optical trapping of francium.

Abstract

We demonstrated a frequency offset locking between two laser sources using a waveguide-type electro-optic modulator (EOM) with 10th-order sidebands for magneto-optical trapping of Fr atoms. The frequency locking error signal was successfully obtained by performing delayed self-homodyne detection of the beat signal between the repumping frequency and the 10th-order sideband component of the trapping light. Sweeping the trapping-light and repumping-light frequencies with keeping its frequency difference of 46 GHz was confirmed over 1 GHz by monitoring the Doppler absorption profile of I2. This technique enables us to search for a resonance frequency of magneto-optical trapping of Fr.