Arbitrary Multiplication and Division of the Orbital Angular Momentum of Light.

Multiplication and division of the orbital angular momentum (OAM) of light are important functions in the exploitation of the OAM mode space for such purposes as high-dimensional quantum information encoding and mode division multiplexed optical communications. These operations are possible with optical transformations that reshape optical wave fronts according to azimuthal scaling. However, schemes proposed thus far have been limited to OAM multiplication by integer factors and require complex beam-copying or multitransformation diffraction stages; a result of the limited phase excursion 2πℓ around the annulus of an OAM state exp(iℓθ).

Spiral Transformation for High-Resolution and Efficient Sorting of Optical Vortex Modes.

Mode sorting is an essential function for optical multiplexing systems that exploit the orthogonality of the orbital angular momentum mode space. The familiar log-polar optical transformation provides a simple yet efficient approach whose resolution is, however, restricted by a considerable overlap between adjacent modes resulting from the limited excursion of the phase along a complete circle around the optical vortex axis. We propose and experimentally verify a new optical transformation that maps spirals (instead of concentric circles) to parallel lines.

Nondiffracting chirped Bessel waves in optical antiguides.

Chirped Bessel waves are introduced as stable (nondiffracting) solutions of the paraxial wave equation in optical antiguides with a power-law radial variation in their index of refraction. Through numerical simulations, we investigate the propagation of apodized (finite-energy) versions of such waves, with or without vorticity, in antiguides with practical parameters. The new waves exhibit a remarkable resistance against the defocusing effect of the unstable index potentials, outperforming standard Gaussians with the same full width at half-maximum.

Curved singular beams for three-dimensional particle manipulation.

For decades, singular beams carrying angular momentum have been a topic of considerable interest. Their intriguing applications are ubiquitous in a variety of fields, ranging from optical manipulation to photon entanglement, and from microscopy and coronagraphy to free-space communications, detection of rotating black holes, and even relativistic electrons and strong-field physics. In most applications, however, singular beams travel naturally along a straight line, expanding during linear propagation or breaking up in nonlinear media.

Temporal cloaking with accelerating wave packets.

We theoretically propose a temporal cloaking scheme based on accelerating wave packets. A part of a monochromatic light wave is endowed with a discontinuous nonlinear frequency chirp, so that two opposite accelerating caustics are created in space-time as the different frequency components propagate in the presence of dispersion. The two caustics open a biconvex time gap that contains negligible optical energy, thus concealing the enclosed events.