title: Azimuthal and radial shaping of vortex beams generated in twisted nonlinear photonic crystals.
abstract: 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.
authors.forename: Keren
authors.initials: K
authors.lastname: Shemer
authors.forename: Noa
authors.initials: N
authors.lastname: Voloch-Bloch
authors.forename: Asia
authors.initials: A
authors.lastname: Shapira
authors.forename: Ana
authors.initials: A
authors.lastname: Libster
authors.forename: Irit
authors.initials: I
authors.lastname: Juwiler
authors.forename: Ady
authors.initials: A
authors.lastname: Arie