Generation of a radially polarized laser beam by use of the birefringence of a c-cut Nd:YVO4 crystal

We demonstrated the generation of a radially polarized laser beam from an extremely simple laser resonator including a c-cut Nd:YVO4 crystal as a laser medium. The oscillation in the radial polarization was based on the optical path difference between an extraordinary ray and an ordinary ray induced by the birefringence of the crystal. By simply adjusting the distance between two cavity mirrors, only the extraordinary ray became stable for the oscillation, resulting in the generation of a radially polarized beam. The beam was very stable even at low power output and is expected to be a promising radially polarized laser source because of its excellent simplicity.