Constructing arbitrary self-similar Bessel-like beams via transverse-longitudinal mapping

Based on the transverse-longitudinal mapping of Bessel beams,we propose a simple method to construct a self-similar Bessel-like beam whose transverse profile maintains a stretched form during propagation.Specifically,the propagatingvariant width of this beam can be flexibly predesigned.We experimentally demonstrate three types of self-similar Bessellike beams whose width variations are linear,piecewise,and period functions of propagation distance,respectively.The experimental results match well with the theoretical predictions.We also demonstrate that our approach enables the generation of self-similar higher-order vortex Bessel-like beams.

Linear and nonlinear photonic spin Hall effect induced by analog circular birefringence of Bessel-like beams

The spin Hall effect of a light beam is essentially a product of circular birefringence but is rarely demonstrated.Here,we provide a scheme for initiating off-axis circular birefringence based on the spin-dependent wave vector bifurcation of Bessel beams via a single liquid crystal Pancharatnam–Berry phase element.The tilted Bessel beam shows a detectable photonic spin Hall effect.By introducing the nonlinear propagation trajectories,the spin Hall effect is greatly enhanced.More surprisingly,the two spin states exactly propagate along the scaled trajectories,enabling flexible control of the spin separation.This phenomenon is also applicable to other Bessel-like beams with nonlinear trajectories,which have been already reported.

Controllable oscillated spin Hall effect of Bessel beam realized by liquid crystal Pancharatnam-Berry phase elements

Pancharatnam–Berry (PB) phase has become an effective tool to realize the photonic spin Hall effect (PSHE) in recent years, due to its capacity of enhancing the spin-orbit interaction. Various forms of PSHEs have been proposed by tailoring the PB phase of light, however, the propagation trajectory control of the separated spin states has not been reported. In this paper, we realize the oscillated spin-dependent separation by using the well-designed PB phase optical elements based on the transverse-to-longitudinal mapping of Bessel beams. Two typical oscillated PSHEs, i.e., the spin states are circulated and reversed periodically, are experimentally demonstrated with two PB phase elements fabricated with liquid crystal. The displacements and periods of these oscillations can be controlled by changing the transverse vector of the input Bessel beam. The proposed method offers a new degree of freedom to manipulate the spin-dependent separation, and provides technical supports for the application in spin photonics.