We experimentally demonstrate that the orbital angular momentum (OAM) of a second harmonic (SH) beam, generated within twisted nonlinear photonic crystals, depends both on the OAM of the input pump beam and on the quasi-angular momentum of the crystal. In addition, when the pump’s radial index is zero, the radial index of the SH beam is equal to that of the nonlinear crystal. Furthermore, by mixing two noncollinear pump beams in this crystal, we generate, in addition to the SH beams, a new “virtual beam” having multiple values of OAM that are determined by the nonlinear process.
© 2013 Optical Society of America
Original Manuscript: July 8, 2013
Revised Manuscript: September 24, 2013
Manuscript Accepted: November 14, 2013
Published: December 13, 2013
Keren Shemer, Noa Voloch-Bloch, Asia Shapira, Ana Libster, Irit Juwiler, and Ady Arie, "Azimuthal and radial shaping of vortex beams generated in twisted nonlinear photonic crystals," Opt. Lett. 38, 5470-5473 (2013)