Abstract
A spatiotemporal optical vortex (STOV) is an intrinsic optical orbital angular momentum (OAM) structure in which the OAM vector is orthogonal to the propagation direction [Optica 6, 1547 (2019)OPTIC82334-253610.1364/OPTICA.6.001547] and the optical phase circulates in space-time. Here, we experimentally and theoretically demonstrate the generation of the second harmonic of a STOV-carrying pulse along with the conservation of STOV-based OAM. Our experiments verify that photons can have intrinsic orbital angular momentum perpendicular to their propagation direction.
Highlights
A spatiotemporal optical vortex (STOV) [1,2] is an electromagnetic structure with orbital angular momentum (OAM) and optical phase circulation defined in space-time and is supported by a polychromatic pulse [3]
For a STOV-carrying pulse propagating in free space [2], the OAM vector is perpendicular to the direction of propagation
This contrasts with a conventional space-defined optical vortex, which can be supported by a monochromatic beam, and where the OAM vector is parallel/anti-parallel to the direction of propagation and the optical phase winding is in the plane transverse to propagation [4-6]
Summary
A spatiotemporal optical vortex (STOV) [1,2] is an electromagnetic structure with orbital angular momentum (OAM) and optical phase circulation defined in space-time and is supported by a polychromatic pulse [3]. In this paper we demonstrate, for the first time, the second harmonic generation (SHG) of STOVs and conservation of STOV orbital angular momentum.
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