Broadband optically pumped NMR gyroscope technique based on Gaussian white noise phase modulation

This work proposes an optical pumping strategy based on a broadband laser to overcome the problem of atomic spin polarization gradients and sensitivity to optical frequency noise in NMR gyroscopes. A band-limited Gaussian white noise radiofrequency signal is applied to a lithium niobate electro-optic phase modulator to do this. A narrow linewidth laser maintains its frequency stability while uniformly broadening its spectrum to the hundreds of MHz range. Compared to unmodulated pumping, the proposed scheme enhances the uniformity of rubidium spin polarization by approximately 10%, reaching a measured value of 92.8%. Additionally, the sensitivity of the inert gas precession signal to optical frequency noise is reduced by half. This scheme can be extended to other atomic sensors requiring higher uniform spin polarization distributions and provides a promising way to achieve high-stability, low-noise NMR gyroscope systems.