2?m cylindrical vector beam generation from a c-cut Tm:CaYAlO4 crystal resonator

Different from the traditional ideal column symmetry cavities, we directly generated the cylindrical vector pulsed beams in the folded six-mirror cavity by employing a c-cut Tm:CaYAlO4 (Tm:CYA) crystal and SESAM. By adjusting the distance between the curved cavity mirror (M4) and the SESAM, both the radially polarized beam and azimuthally polarized beam are generated around 1962 nm and the two vectorial modes can be freely switched in the resonator. Further increased the pump power to 7 W, the stable radially polarized Q-switched mode-locked (QML) cylindrical vector beams were also obtained with an output power of 55 mW, the sub-pulse repetition rate of 120.42 MHz, pulse duration of -0.5 ns and the beam quality factor M2 of -2.9. To our knowledge, this is the first report of radially and azimuthally polarized beams in the 2 mu m wavelength solid-state resonator.

Automated summary

In this study, we generated cylindrical vector pulsed beams by using a c-cut Tm:CaYAlO4 crystal and SESAM in a folded six-mirror cavity. By adjusting the distance between the curved cavity mirror (M4) and the SESAM, both radially polarized beam and azimuthally polarized beam were generated around 1962 nm and the two vectorial modes could be freely switched in the resonator. When the pump power was increased to 7 W, stable radially polarized Q-switched mode-locked (QML) cylindrical vector beams were obtained with an output power of 55 mW, sub-pulse repetition rate of 120.42 MHz, pulse duration of -0.5 ns, and the beam quality factor M2 of -2.9. To our knowledge, this is the first report of radially and azimuthally polarized beams in the 2 μm wavelength solid-state resonator.