Formation of laser geometric modes with orthogonally polarized states by a c-cut Nd:YVO₄ laser in a concave-convex cavity

Wei-Ru Chen^1*, Pi-Hui Tuan¹

¹Department of Physics, National Chung Cheng University, Chiayi, Taiwan

* Presenter:Wei-Ru Chen, email:ruby632354@gmail.com

The laser geometric mode with its intensities localized on the classical periodic orbit of resonator is one of the most intriguing structured lights which not only beautifully manifests ray-wave correspondence but offers high degrees of freedom (DoFs) for multiple functionalities. By leveraging the inherent birefringence of the c-cut Nd:YVO₄ gain crystal, geometric modes corresponding to the same transverse-longitudinal coupling condition but with orthogonally polarized states are realized in an off-axis pumped concave-convex resonator. Agreeing well with the theoretical analysis, experimental results reveal that the polarized state of geometric mode is switched from the s-polarization (perpendicular to the trajectory plane) to the p-polarization (parallel to the trajectory plane) when the cavity length is turned from a shorter to longer one around a certain degenerate condition. Furthermore, both the intracavity intensity distributions and the output power for the orthogonally polarized geometric modes are examined to be almost the same, reflecting nearly identical gain condition can be nicely switched from s- to p-polarization by merely adjusting the cavity length. It is believed that the easily-turned polarization switching can provide an additionally controllable DoF for potential applications.

Keywords: Laser geometric modes, orthogonally polarization switching, solid-state lasers