VCSEL frequency stabilization for optically pumped magnetometers

Optically pumped magnetometers(OPMs) have developed rapidly in the bio-magnetic measurement field,which requires lasers with stable frequency and intensity for high sensitivity.Herein we stabilize a vertical-cavity surface-emitting laser(VCSEL) without any additional setup except for the parts of an OPM.The linewidth of the absorption spectrum as a frequency reference is broadened to 40 GHz owing to pressure broadening.To enhance performance,the VCSEL injection current and temperature are tuned simultaneously using a closed-loop control system.The experiments reveal that the VCSEL frequency stability achieves 2 × 10-7at an average time of 1 s,and the intensity noise is 1 × 10-6V/Hz1/2at 1-100 Hz.This approach is useful for suppressing OPM noise without additional sensor probe parts.