Polarization-switchable geometric-mode pulses with high temporal stability in an Nd:YVO₄/Cr⁴⁺:YAG concave-convex...

Laser geometric modes with switchable orthogonal polarization are explored in a c-cut Nd:YVO₄ laser with a symmetric concave-convex resonator under both continuous-wave (CW) and passively Q-switched (PQS) operation. By leveraging birefringent thermal lensing to separate degenerate cavity configurations for the orthogonally polarized bases, the output polarization of CW and PQS geometric modes can be switched between s- and p-polarized states (perpendicular and parallel to the trajectory plane, respectively) simply by tuning the cavity length. Under optimized conditions, the dominant polarized states exhibit well-defined spatial structures with clearly localized beam spots. Furthermore, the polarization-switchable PQS geometric modes demonstrate stable pulse trains with peak-to-peak amplitude fluctuations below 10%. Experimental results reveal that the overall peak power for the pulsed geometric modes with easily tunable s- and p-polarization can exceed 550 W, highlighting their potential for practical applications.