We review and clarify several recent theoretical approaches to transverse orbital angular momentum (tOAM). We then apply our tOAM theory [Phys. Rev. Lett. 127, 193901 (2021)] to calculate the spatiotemporal torque applied to a light pulse by a pure amplitude perturbation. The theoretical results and associated simulations are in excellent agreement with experiments measuring the change in tOAM per photon, delta_Ly. The crucial factor in determining delta_Ly is the spatiotemporal distribution of tOAM density in the pulse. We show that even Gaussian pulses with zero total tOAM can have net tOAM induced by an amplitude perturbation stationary in the lab frame.

Hydrodynamic plasma waveguides initiated by optical field ionization have recently become a key component of multi-GeV laser wakefield accelerators. Here, we present the most complete and accurate experimental and simulation-based characterization to date, applicable to current multi-GeV experiments and future 100 GeV-scale laser plasma accelerators. Crucial to the simulations is the correct modeling of intense Bessel beam interaction with meter-scale gas targets, the results of which are used as initial conditions for hydrodynamic simulations. The simulations are in good agreement with our experiments measuring evolving plasma and neutral hydrogen density profiles using two-color short pulse interferometry, enabling realistic determination of the guided mode structure for application to laser-driven plasma accelerator design.

Light with orbital angular momentum orthogonal to propagation can exist in free space and as emergent structures integral to self-focused propagation. I will review our first observations, recent results on STOV -matter interactions, and possible applications.

We demonstrate the controlled spatiotemporal transfer of transverse orbital angular momentum (OAM) to electromagnetic waves: the spatiotemporal torquing of light. This is a radically different situation than OAM transfer to longitudinal, spatially-defined OAM light by stationary or slowly varying refractive index structures such as phase plates or air turbulence. We show that transverse OAM can be imparted to a short light pulse only for (1) sufficiently fast transient phase perturbations overlapped with the pulse in spacetime, or (2) energy removal from a pulse that already has transverse OAM. Our OAM theory for spatiotemporal optical vortex (STOV) pulses [Phys. Rev. Lett. 127, 193901 (2021)] correctly quantifies the light-matter interaction of this experiment, and provides a torque-based explanation for the first measurement of STOVs [Phys. Rev. X 6, 031037 (2016)].

This publisher's note contains corrections to Opt. Lett.46, 1013 (2021)OPLEDP0146-959210.1364/OL.417803.

We identify a class of modal solutions for spatiotemporal optical vortex (STOV) electromagnetic pulses propagating in dispersive media with orbital angular momentum (OAM) orthogonal to propagation. We find that symmetric STOVs in vacuum can carry half-integer intrinsic OAM; for general asymmetric STOVs in a dispersive medium, the OAM is quantized in integer multiples of a parameter that depends on the STOV symmetry and the group velocity dispersion. Our results suggest that STOVs propagating in dispersive media are accompanied by a polaritonlike quasiparticle. The modal theory is in excellent agreement with measurements of free space propagation of STOVs.

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 [Optica 6, 1547, (2019)] 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 verify that individual photons can have intrinsic orbital angular momentum perpendicular to their propagation direction.

We present results on the modal and quasi-modal linear propagation in a dispersive medium of ultrashort pulses carrying spatiotemporal optical vortices. We isolate contributions of wavefront tilt and dispersion to the optical angular momentum.

Spatiotemporal optical vortices (STOVs) are a new type of optical orbital angular momentum (OAM) residing in the space-time domain. Here we examine, through experiment and simulation, how STOV OAM is transformed in second-harmonic generation.

Spatiotemporal optical vortices (STOVs) are a new type of optical orbital angular momentum (OAM) residing in the space-time domain. Here we examine, through experiment and simulation, how STOV OAM is transformed in second-harmonic generation.

Spatiotemporal optical vortices (STOVs), arise naturally during nonlinear self-focusing collapse arrest. Here, we use a 4-f pulse shaper to impose STOVs linearly on a Gaussian pulse and directly measure the vortex in spatiotemporal domains.

Spatiotemporal Optical Vortices (STOVs), optical orbital angular momentum structures arising naturally in collapsing laser pulses, are crucial to filament propagation. We characterize STOVs directly in the spatiotemporal domain.

We measure the detailed spatiotemporal profiles of femtosecond laser pulses in the infrared wavelength range of λ=2.5-11  μm and the absolute nonlinear response of major air constituents (N2, O2, and Ar) over this range. The spatiotemporal measurements reveal wavelength-dependent pulse front tilt and temporal stretching in the infrared pulses.

Spatio-temporal optical vortices (STOVs) are a new type of optical orbital angular momentum (OAM) with optical phase circulation in space-time. In prior work [N. Jhajj et al., Phys. Rev X 6, 031037 (2016)], we demonstrated that a STOV is a universal structure emerging from the arrest of self-focusing collapse leading to nonlinear self-guiding in material media. Here, we demonstrate linear generation and propagation in free space of STOV-carrying pulses. Our measurements and simulations demonstrate STOV mediation of space-time energy flow within the pulse and conservation of OAM in space-time. Single-shot amplitude and phase images of STOVs are taken using a new diagnostic, transient grating single-shot supercontinuum spectral interferometry (TG-SSSI).

We measure the nonlinear refractive indices of major air constituents (N2, O2, Ar) in the wavelength range of λ = 2.5μm−10.6μm, extending the range of prior measurements [1]. These results are important for the study of intense laser propagation in the atmosphere.