A novel orthogonal polarized dual-frequency laser using a Y-shaped cavity

In this paper, we propose and demonstrate a novel dual-frequency He–Ne laser based on a Y-shaped cavity. The laser uses a polarization beam splitter to produce two orthogonal polarized beams that oscillate simultaneously in different sub-cavities. The different optical lengths of the cavities produce two longitudinal mode series with different mode spacing. In our experiments, a frequency difference between two orthogonal polarized lights ranging from 26 to 665 MHz was observed by changing the voltage applied to the piezoelectric transducer attached to the mirror of P polarized sub-cavity. The lock-in frequency difference is about 26 MHz. The competing processes were also investigated.