Propagation of high-order circularly polarized Bessel beams and vortex generation in uniaxial crystals

We investigate the generation and transformation of Bessel beams through linear and nonlinear optical crystals. We outline the gen- eration of high-order vortices due to propagation of Bessel beams along the optical axis of uniaxial crystals and expand this to the nonlinear regime by outlining a new phase-matching process (full conical phase matching) in second harmonic generation of vector Bessel beams for various sym- metries in uniaxial crystals. We demonstrate the principles experimentally in a uniaxial BBO crystal and find excellent agreement between the ex- perimental and theoretical results. The results imply a coupling of the intrinsic and extrinsic optical angular momentum of the resulting fields, which may have importance in studies involving quantum entanglement of the angular momentum basis of light. C 2011 Society of Photo-Optical Instru-