Study on dual-frequency difference tuning characteristics of microchip cavity with two transverse mode output

Two perpendicularly polarized transverse mode modes can be generated by a bipolarized laser resonator, namely fundamental transverse mode (TEM₀₀) and vortex beam with orbital angular momentum (LG₀₁). There is frequency difference in optical frequency. In order to study frequency difference tuning characteristics of two transverse modes, tuning technique combining temperature and voltage was adopted. Continuous tuning of beat signal in different frequency ranges was realized. The relationship between frequency difference of two modes vs. temperature and voltage was analyzed theoretically. Experiments showed that frequency difference can be tuned in wide range. Tuning accuracy of frequency difference was measured and analyzed. The results show that, there is good linear relationship between frequency difference vs. temperature and voltage. The tuning slopes of temperature and voltage are 3.14GHz/K and 1.76MHz/V, respectively. This study can better analyze the phenomenon of vortex beam generated directly by dual polarization resonator. It has application value in the fields of laser communication and lidar detection.