How to measure the optical conductivity of atomically thin crystals is an important but challenging issue due to the weak light-matter interaction at the atomic scale. Photonic spin Hall effect, as a fundamental physical effect in light-matter intera
ction, is extremely sensitive to the optical conductivity of atomically thin crystals. Here, we report a precision measurement of the optical conductivity of graphene, where the photonic spin Hall effect acts as a measurement pointer. By incorporating with the weak-value amplification technique, the optical conductivity of monolayer graphene taken as a universal constant of $(0.993pm0.005)sigma_0$ is detected, and a high measuring resolution with $1.5times10^{-8}Omega^{-1}$ is obtained. For few-layer graphene without twist, we find that the conductivities increase linearly with layer number. Our idea could provide an important measurement technique for probing other parameters of atomically thin crystals, such as magneto-optical constant, circular dichroism, and optical nonlinear coefficient.
We propose that the full Poincar{e} beam with any polarization geometries can be pictorially described by the hybrid-order Poincar{e} sphere whose eigenstates are defined as a fundamental-mode Gaussian beam and a Laguerre-Gauss beam. A robust and eff
icient Sagnac interferometer is established to generate any desired full Poincar{e} beam on the hybrid-order Poincar{e} sphere, via modulating the incident state of polarization. Our research may provide an alternative way for describing the full Poincar{e} beam and an effective method to manipulate the polarization of light.
We report the realization of tunable spin-dependent splitting in intrinsic photonic spin Hall effect. By breaking the rotational symmetry of a cylindrical vector beam, the intrinsic vortex phases that the two spin components of the vector beam carrie
s, which is similar to the geometric Pancharatnam-Berry phase, is no longer continuous in the azimuthal direction, and leads to observation of spin accumulation at the opposite edge of the beam. Due to the inherent nature of the phase and independency of light-matter interaction, the observed photonic spin Hall effect is intrinsic. Modulating the topological charge of the vector beam, the spin-dependent splitting can be enhanced and the direction of spin accumulation is switchable. Our findings may provide a possible route for generation and manipulation of spin-polarized photons, and enables spin-based photonics applications.
We develop a geometric photonic spin Hall effect (PSHE) which manifests as spin-dependent shift in momentum space. It originates from an effective space-variant Pancharatnam-Berry (PB) phase created by artificially engineering the polarization distri
bution of the incident light. Unlikely the previously reported PSHE involving the light-matter interaction, the resulting spin-dependent splitting in the geometric PSHE is purely geometrically depend upon the polarization distribution of light which can be tailored by assembling its circular polarization basis with suitably magnitude and phase. This metapolarization idea enables us to manipulate the geometric PSHE by suitably tailoring the polarization geometry of light. Our scheme provides great flexibility in the design of various polarization geometry and polarization-dependent application, and can be extrapolated to other physical system, such as electron beam or atom beam, with the similar spin-orbit coupling underlying.
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 t
he 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. Here, we demonstrate experimentally a scheme to realize the photonic SHE tunably by tailoring the space-variant Pancharatnam-Berry phase (PBP). It is shown that light beams whose polarization with a tunable spatial inhomogeneity can contribute to steering the space-variant PBP which creates a spin-dependent geometric phase gradient, thereby possibly realizing a tunable photonic SHE with any desired spin-dependent splitting. Our scheme provides a convenient method to manipulate the spin photon. The results can be extrapolated to other physical system with similar topological origins.
An inhomogeneous anisotropic medium with specific structure geometry can apply the tunable spin-dependent geometrical phase to the light passing through the medium, and thus can be used to steer the spin-dependent splitting (SDS) of light. In this pa
per, we exemplify this inference by the q plate, an inhomogeneous anisotropic medium. It is demonstrated that when a linearly polarized light beam normally passes through a q plate, k-space SDS first occurs, and then the real-space SDS in the far-field focal plane of a converging lens is distinguishable. Interestingly, the SDS, described by the normalized Stokes parameter S3 shows a multilobe and rotatable splitting pattern with rotational symmetry. Further, by tailoring the structure geometry of the q plate and/or the incident polarization angle of light, the lobe number and the rotation angle both are tunable. Our result suggests that the q plate can serve as a potential device for manipulating the photon spin states and enable applications such as in nano-optics and quantum information.
We present a metamaterial-based random polarization control plate to produce incoherent laser irradiation by exploiting the ability of metamaterial in local polarization manipulation of beam upon transmission via tuning its local geometry. As a proof
-of-principle, we exemplify this idea numerically in a simple optical system using a typical L-shaped plasmonic metamaterial with locally varying geometry, from which the desired polarization distribution can be obtained. The calculating results illustrate that this scheme can effectively suppress the speckle contrast and increase irradiation uniformity, which has potential to satisfy the increasing requirements for incoherent laser irradiation.
We present a physical explanation of Zitterbewegung-like effect near the zero-refractive-index point in a metamaterial slab in this paper. Between the negative and positive refractive index regions centered at the zero-refractive-index point, the tra
nsmittance spectrum distribution of the metamaterial slab is asymmetrical. When a symmetrical pulse propagates through the metamaterial slab, its transmitted spectrum becomes asymmetrical due to the asymmetry of the transmittance spectrum of the slab, leading to a transmitted pulse with an asymmetrical temporal shape. The asymmetry manifests a kind of temporally tailed oscillations, i.e., the Zitterbewegung-like effect. Further, the effect of the temporal and spatial widths of pulse, and the thickness of metamaterial slab on the tailed oscillations of the transmitted pulse has also been discussed. Our results agree well with what the other researchers obtained on the strength of relativistic quantum concepts; however, the viewpoint of our analysis is classical and irrelevant to relativistic quantum mechanics.
