Second harmonic generation and orthogonal orbital angular momentum of spatiotemporal optical vortices

Spatiotemporal optical vortices (STOVs) are a new type of intrinsic optical orbital angular momentum (OAM) structure in which the OAM vector is orthogonal to the propagation direction [1,2] and the optical phase circulates in space-time. Here, we experimentally and theoretically demonstrate, for the first time, the generation of the second harmonic of a STOV-carrying pulse along with the conservation of STOV-based OAM. Our experiments and calculations [3] verify that photons can have intrinsic orbital angular momentum perpendicular to their propagation direction.

[1] S. W. Hancock, S. Zahedpour, A. Goffin, and H. M. Milchberg, Optica 6, 1547 (2019).

[2] N. Jhajj, I. Larkin, E. W. Rosenthal, S. Zahedpour, J. K. Wahlstrand and H. M. Milchberg, Phys. Rev. X. 6, 031037 (2016)

[3] S. W. Hancock, S. Zahedpour, and H. M. Milchberg, under review.