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 x 10-7 at an average time of 1 s, and the intensity noise is 1 x 10-6 V/Hz1/2 at 1-100 Hz. This approach is useful for suppressing OPM noise without additional sensor probe parts.

Automated summary

By simultaneously adjusting VCSEL injection current and temperature, the optical system of optically pumped magnetometers (OPMs) has achieved improved stability with a frequency stability of 2 x 10-7 and intensity noise of 1 x 10-6 V/Hz1/2, effectively suppressing OPM noise without the need for additional sensor probe parts.