SWAP and Fredkin gates for OAM optical beams via the sandwich of anisotropic optical fibers.

We study the propagation of circularly-polarized optical vortices of higher order topological charges ℓ ≥ 2 in a sandwich of multihelical - anisotropic - multihelical fibers on the basis of the Jones formalism for modes with orbital angular momentum. We demonstrate that such a system can operate as the all - fiber two - bit SWAP as well as universal tree - bit controlled-SWAP (Fredkin) gates over states of optical vortices, in which the mode radial number carries the control bit, while circular polarization and topological charge are the controlled bits.

Topological Faraday Effect for Optical Vortices in Magnetic Films.

Here we experimentally demonstrate the topological Faraday effect-the polarization rotation caused by the orbital angular momentum of light. It is found that the Faraday effect of the optical vortex beam passing through a transparent magnetic dielectric film differs from the Faraday effect for a plane wave. The additional contribution to the Faraday rotation depends linearly on the topological charge and radial number of the beam. The effect is explained in terms of the optical spin-orbit interaction. These findings underline the importance of using the optical vortex beams for studies of magnetically ordered materials.

Generation of optical vortices in non-parity-time-symmetric chiral-core optical fibers.

In this Letter, we have studied the effect of losses and gains on generation of optical vortices (OVs) in a chiral fiber with an l-fold rotational symmetric core. Studying both unequal attenuations and symmetric loss-gain cases for core and orbital angular momentum (OAM) modes, we show that losses may play a constructive role in generation of OVs from a Gaussian input. We study the processes of field evolution at the exceptional point (EP). We show that at the EP any superposition of the fundamental mode and l-charge OV evolves in the limit into an equal-weighted superposition of such fields that forms a special attractor mode with average l/2 OAM per photon. At the generalized Poincare sphere, such a mode is represented by the OAM black hole in analogy with the spin black hole introduced in [Optica3, 1025 (2016)OPTIC82334-253610.1364/OPTICA.3.001025].

Amplification of optical activity in a fiber loop resonator.

In this paper, we have theoretically studied an effective amplification of optical activity by a fiber loop resonator. We propose a scheme in which an optically active element is placed in the loop segment of the resonator. Assuming that the coupling in the resonator is polarization-independent, we have shown that initially small polarization plane rotation, which arises due to the optically active element, can be significantly amplified by tuning the resonator's closed-path phase. We have also studied the influence of losses on the amplification of optical activity. We have shown that the maximal amplification takes place under the condition of critical coupling, at which the attenuation parameter is equal to the resonator's effective reflection coefficient. We have also studied effective dichroism in such a system and shown the relevance of a critical coupling regime to that effect.

Transmission of optical vortices through fiber loop resonators.

In this Letter, we study the propagation of optical vortices (OVs) through the loop resonator (LR) on a multimode fiber. We demonstrate the existence of a special resonance, which is in the inversion of the topological charge of the transmitted OV. Near the resonance, the output orbital angular momentum (OAM) is sensitive to wavelength-scale variations of the LR's optical path length, which can be used for super-efficient OAM control. We also show the feasibility of a combined wavelength and OAM division multiplexing in comb filters on such LRs.

Revised model of acousto-optic interaction in optical fibers endowed with a flexural wave.

We propose a novel model of the acousto-optic interaction in circular fibers endowed with the lowest-order flexural acoustic wave that is based on the actual distribution of the acoustically induced displacement vector. The corresponding expression for the fiber's permittivity is derived and compared with the commonly used one. The resonance optical fiber modes and the propagation constants are found. It is predicted that the lengths of the well-known acoustically driven mode conversion LP0,n→LP1,n' should be slightly different for the x- and y-polarized incident fundamental modes. Moreover, we unveil a new polarization-dependent mode conversion in which the azimuthal mode number ℓ, as well as the optical frequency of the generated standard fiber mode LPℓ,n' , is governed by the linear polarization direction of the incident zero-order beam LP0,n.