Two-channel whispering gallery mode self-injection locking lasers for hybrid optically pumped atomic comagnetometers
Qingbo Liu, Lihong Duan, Ning Ma, Gang Liu
Abstract
Hybrid optically pumped atomic comagnetometers require low-noise pumping and probing lasers that exhibit tens of terahertz frequency difference. By exploiting the large free spectral range of a microresonator and the characteristics of self-injection locking, two-channel low-noise lasers with a 12.4 THz frequency difference are achieved by simultaneous self-injection locking with different whispering gallery modes of a microresonator with a quality factor of 10 9 . The feasibility of simultaneous self-injection locking is theoretically validated using rate equations. In simultaneous self-injection locking condition, the linewidths of both lasers are compressed 50 times, the frequency noises are decreased by 150 times compared to free-running lasers, and the output wavelengths maintain stable without hopping. The two-channel lasers, with large frequency difference and prominent low noise, is applicable to high-sensitivity atomic comagnetometers. • A two-channel whispering gallery mode self-injection locking lasers model is built. • A microresonator that generates given resonant modes is designed. • The self-injection locking of two lasers with the microresonator is achieved. • The frequency noises and linewidths of both lasers are reduced.