VECSEL for IR-laser threshold magnetometry with active stability control (Keynote Presentation)

Laser threshold magnetometry (LTM) promises a path towards significant reductions in optical power and volume for high sensitivity diamond nitrogen-vacancy (NV) magnetometers. LTM utilizes the difference in laser threshold due to intra-cavity diamond absorption while driving the RF spin resonance. To gain the maximum benefit from this technique, the diamond containing vertical external cavity surface emitting laser (VECSEL) is held as close to the lasing threshold as possible. Since laser cavities near threshold tend to experience higher noise, a combination of power and frequency stabilization have been implemented to reduce intensity noise while operating 0.1% above threshold. We have experimentally shown contrasts above 34% and photon shot noise limits of 26 pT/Hz^1/2 and will demonstrate the possibility of further improvement through optimized cavity design.