Generation of azimuthally and radially polarized off-axis beams with an intracavity large-apex-angle axicon.

Depending on cavity configuration, a c-cut Nd:YVO4 laser by using a large-apex-angle axicon can execute azimuthally and radially polarized operations. A large-apex-angle axicon dominates and stabilizes the generation of the pattern, and expands the difference between the ordinary and extraordinary rays to generate off-axis cylindrical vector beams. When the cavity length is properly adjusted, the polarization of off-axis laser beams can exhibit a transition from azimuthal to radial polarization. The degree of polarizations can be up to 95.4% ± 2.6% and 94% ± 3.7% for azimuthally and radially polarized beams, respectively; and the slope efficiencies are approximately 20.5% for both polarized operations. Using two-pass-mode ray tracing, the ray generating mechanisms and divergent angles of their patterns were analyzed.