Metasurface-Assisted Quantum Nonlocal Weak-Measurement Microscopy.

In standard quantum weak measurements, preselection and postselection of quantum states are implemented in the same photon. Here we go beyond this restrictive setting and demonstrate that the preselection and postselection can be performed in two different photons, if the two photons are polarization entangled. The Pancharatnam-Berry phase metasurface is incorporated in the weak measurement system to perform weak coupling between probe wave function and spin observable.

Quadratic spin Hall effect of light due to phase change.

The spin Hall effect (SHE) of light has brought important applications, but the involved spin states only split in one direction. Here we employ an accurate three-dimensional model of light to show that the SHE generally exhibits quadratic spin splitting, i.e.

Topological spatial differentiators upon reflection of the normally incident light.

We theoretically propose topological spatial differentiators by the normal-incidence reflection of light. Firstly, a three-dimensional propagation model is established for the light normally incident on the interface between two media. It is found that due to the spin-orbit interaction of light, a given circularly polarized light always induces oppositely polarized light carrying a topological charge, so the two intrinsic spin components are separated radially or azimuthally.

Computing metasurfaces enabled chiral edge image sensing.

Computing metasurfaces have shown the extraordinary ability to precisely perform optical analog operations to the input light wave, and therefore exhibit greater potentials toward sensing applications. Here, we propose a unique application of computing metasurface for chiral edge sensing by incorporating a weak-value amplification technique. The computing metasurface performs the spatial differentiation operations of phase objects and extracts the edge-enhanced images, because the phase gradient generally occurs at the edge.

Spatial differential operation and edge detection based on the geometric spin Hall effect of light.

Unlike the conventional spin Hall effect of light (SHEL) originating from the light-matter interaction, the spin-dependent splitting in the geometric SHEL is purely a geometric effect and independent from the properties of matter. Here it is shown that the geometric SHEL is not only of fundamental theoretical interest in understanding the spin-orbit interaction of light, but also sheds light on important technological applications. This Letter describes the theoretical foundation and experimental realization of optical differential operation and one-dimensional edge detection based on the geometric SHEL.

Transitional Goos-Hänchen effect due to the topological phase transitions.

We examine the Goos-Hänchen (GH) effect for a Gaussian beam impinging on the surface of silicene whose topological phase transitions can be modulated by external electric field and/or irradiating circular polarized light. It is shown that both the spatial and angular shifts in GH effect present a sharp jump due to the topological phase transitions. The transitional GH effect can be attributed to transitional optical conductivity, which relates to Berry curvature and Chern numbers.

Electrically driven generation of arbitrary vector vortex beams on the hybrid-order Poincaré sphere.

We propose a simple, efficient, and fast tunable method to generate arbitrary vector vortex beams on the hybrid-order Poincaré sphere in an electrically driven way. The scheme incorporates the tunability and switching capabilities of liquid crystals into dielectric metasurfaces to form an efficient vector vortex beam generator. By applying certain voltages on the liquid crystal phase retarder, the generator converts a linearly polarized Gaussian beam into any desirable vector vortex beams.

Precise identification of graphene layers at the air-prism interface via a pseudo-Brewster angle.

We propose a simple method for the precise identification of graphene layers at the air-prism interface via a pseudo-Brewster angle, where the horizontally polarized reflection is close to zero. We find that the pseudo-Brewster angle is sensitive to the variation of graphene layers where the pseudo-Brewster angle is approximately linearly increased about 0.5 deg as the layer numbers increased.

Measurements of Pancharatnam-Berry phase in mode transformations on hybrid-order Poincaré sphere.

We report direct measurements of the Pancharatnam-Berry (PB) phase in mode transformations on a hybrid-order Poincaré sphere. This geometric phase arises when the vector vortex states undergo a cyclic transformation over a closed circuit on a hybrid-order Poincaré sphere. The measured PB phase is proportional to the solid angle of the closed circuit, as well as to the variation of the total angular momenta between north and south poles.

Propagation model for vector beams generated by metasurfaces.

A propagation model of vector beams generated by metasurfaces based on vector diffraction theory is established theoretically and verified experimentally. Considering the Pancharatnam-Berry phase introduced by the metasurface, analytical forms of vector beams for arbitrary incident polarization and topological charge of metasurfaces are found in the Fresnel and Fraunhofer diffraction regions, respectively. The complex amplitude of the resultant vector beam can be described in terms of a confluent hypergeometric function, with an intensity profile that manifests concentric rings in the Fresnel region and a single ring in the Fraunhofer one.

Realization of tunable photonic spin Hall effect by tailoring the Pancharatnam-berry phase.

Recent developments in the field of photonic spin Hall effect (SHE) offer new opportunities for advantageous measurement of the optical parameters (refractive index, thickness, etc.) of nanostructures and enable spin-based photonics applications in the future. However, it remains a challenge to develop a tunable photonic SHE with any desired spin-dependent splitting for generation and manipulation of spin-polarized photons.

The role of dispersion in the propagation of rotating beams in left-handed materials.

We theoretically study the role of dispersion in propagation of rotating beams in left-handed materials (LHMs). By modeling the rotating beam as a superposition of two rotating Laguerre-Gaussian beams with opposite chirality, same magnitude and different frequencies, we demonstrate that the rotation property of the rotating beam in LHM is significantly dependent on the sign and strength of dispersion: In the normal dispersion region, the direction of transverse energy flow is reversed compared to the vacuum, due to the negative refractive index of LHM, while in the anomalous dispersion region it may be parallel or antiparallel to that in the case of vacuum, depending on the strength of dispersion. In addition, we find that the angular momentum density can be parallel or antiparallel to the transverse energy flow in LHM, while the angular momentum flow is always opposite to the transverse energy flow.

Construction of a polarization insensitive lens from a quasi-isotropic metamaterial slab.

We propose to employ the quasi-isotropic metamaterial (QIMM) slab to construct a polarization insensitive lens, in which both E- and H-polarized waves exhibit the same refocusing effect. For shallow incident angles, the QIMM slab will provide some degree of refocusing in the same manner as an isotropic negative index material. The refocusing effect allows us to introduce the ideas of paraxial beam focusing and phase compensation by the QIMM slab.