Infrared vertical external cavity surface emitting laser threshold quantum magnetometer

One of the most promising candidates to use as compact high sensitivity magnetometers is the Nitrogen-Vacancy (NV) center, however traditional implementations of this technology are plagued by low collection efficiencies or poor signal contrasts of the Optically Detected Magnetic Resonance (ODMR). Laser Threshold Magnetometry (LTM) offers a path towards both efficient signal collection and high signal contrasts by taking advantage of near threshold laser dynamics. We demonstrate an infrared LTM using a Vertical External Cavity Surface Emitting Laser (VECSEL) with an intra cavity diamond plate doped with NV centers. The VECSEL was tuned to the spin dependent absorption line of the NV centers, which tied the VECSEL output power to the magnetic field sensed by the NV centers. Furthermore, the contrast and the projected sensitivity limit are shown to improve when operating close to the lasing threshold. We measure a sensitivity of 7.5 nT/√ Hz between 10-50 Hz with a contrast of 18.4% and a projected Photon Shot Noise Limited (PSNL) sensitivity of 26.6 pT/√ Hz close to threshold. We also observe a saturable absorption-like effect near threshold, which further enhances the signal contrast and projected PSNL near threshold. A rate equation model for the VECSEL threshold magnetometer is described and is fit to mimic the observed threshold dynamics.

氮空位（NV）中心是用作紧凑型高灵敏度磁力仪的最有前景的候选之一，然而该技术的传统实现方式受到光探测磁共振（ODMR）的低收集效率或不良信号对比度的困扰。激光阈值磁力测量法（LTM）通过利用近阈值激光动力学，为高效信号收集和高信号对比度提供了一种途径。我们展示了一种使用垂直外腔面发射激光器（VECSEL）以及腔内镶嵌有NV中心的金刚石片的红外LTM。VECSEL被调谐到NV中心的自旋相关吸收线，这将VECSEL的输出功率与NV中心所感知的磁场联系起来。此外，当在接近激光阈值处工作时，对比度和预计的灵敏度极限都有所提高。我们测量到在10 - 50Hz之间的灵敏度为7.5 nT/√Hz，对比度为18.4%，并且在接近阈值处预计的光子散粒噪声极限（PSNL）灵敏度为26.6 pT/√Hz。我们还在阈值附近观察到一种类似可饱和吸收的效应，这进一步提高了阈值附近的信号对比度和预计的PSNL。描述了VECSEL阈值磁力仪的速率方程模型，并对其进行拟合以模拟所观察到的阈值动力学。