Self-Mixing Interference in Dual-Polarization Microchip Nd:YAG Lasers

The self-mixing interference in dual-polarization microchip Nd:YAG lasers is demonstrated. Under optical feedback, the orthogonal polarization components of the laser would undergo antiphase intensity modulations; at high feedback level, the polarization switching appears. We also observe that the laser self-mixing sensitivity changes periodically with the frequency difference of orthogonal polarizations. An initial theoretical model is put out and agrees well with the experiments. The results are useful for self-mixing sensitivity enhancement and offer a new way of absolute distance measurement.