Mode structure and orbital angular momentum of spatiotemporal optical vortex (STOV) pulses

Spatiotemporal optical vortex (STOVs)-carrying pulses are a recently discovered class of polychromatic optical structures with orbital angular momentum (OAM) orthogonal to the direction of propagation [1-3].

In this work we identify a class of modal solutions for STOVs propagating in vacuum and dispersive media. These results show that STOVs can carry half-integer units of intrinsic OAM in vacuum.  The results are in excellent agreement with our experiments [2,3]. In a dispersive medium, a STOV-carrying pulse is accompanied by a half-integer polariton-like quasiparticle with STOV OAM, which we call a “STOV polariton”. Spatiotemporal phase circulation about a STOV singularity suggests that single-valuedness of states under spacetime coordinate rotations in a boosted frame is not a constraint for electromagnetic fields [3].

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

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

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