The Manipulation And Detection Of Spin Of Photons Based On Metasurfaces

The traditional way of manipulating the wavefront of light is mainly based on the Huygens-Fresnel principle: every point of the wavefront can be considered as the source of the secondary spherical wavelet,which spreads forward at the speed of light.The tangential surface of the two wavelets constitutes a new wavefront.These optics elements include prisms,lens and spiral phase plates.The main feature of these devices is that the accumulation of phase depends on the propagation path of the light.Such conventional optical devices tend to be bulky and cumbersome,especially in irregularly shaped optics,which is almost impossible for optical integration and miniaturization.The super-surface,that is,the three-dimensional metamaterial wit h reduced dimensions,can introduce discontinu ous phase discontinuity of the interface to achieve complete control of the phase,amplitude and polarization of the electromagnetic wave.The ultra-thin and planar geometry of the optical super-surface makes it possible to integrate and develop compact,versatile optics with other optics,including conventional optics.Among them,the Pancharatnam-Berry phase(geometric phase)super surface produces a spin-related phenomenon,which makes the left-hand circular polarization and the right-hand circularly polarized light have different transmission behaviors.1.We propose a novel method for the generation of Airy vortex and Airy vector beams based on the modulation of dynamic and geometric phases.In our scheme,the Airy beam is generated by the dynamic phase with a spatial light modulator,and the vortex phase or the vector polarization is modulated by the geometric phase with a dielectric metasurface.The modulation of the geometric phase provides an extra degree of freedom to manipulate the phase and the po larization of Airy beams.This scheme can be extended to generate any other types of optical beams with desirable phase and polarization.We examine the spin-dependent manipulating of vector beams by tailoring the inhomogeneous polarization.The spin-dependent manipulating is attributed to the spin-dependent phase gradient in vector beams,which can be regarded as the intrinsic feature of inhomogeneous polarization.The desired polarization can be obtained by establishing the relationship between the local orientation of polarization and the local orientation of the optical axis of waveplate.We demonstrate that the spin-dependent manipulating with arbitrary intensity patterns can be achieved by tailoring the inhomogeneous polarization.2.Meta-lens represents a promising solution for optical communications and information processing owing to its miniaturization capability and desirable optical properties.Here,spin Hall metalens is demonstrated to manipulate photonic spin-dependent splitting induced by spin-orbital interaction in transverse and longitudinal directions simultaneously at visible wavelengths,with low dispersio n and more than 90% diffraction efficiency.The broadband dielectric spin Hall meta-lens is achieved by integrating two geometric phase lenses with different functionalities into one single dynamic phase lens,which manifests the ultracompact,portable,and polarization-dependent features.The broadband spin Hall meta-lens may find important applications in imaging,sensing,and multifunct ional spin photonics devices.3.Similar to amplitude and phase,optical spin plays an important and nontrivial role in optics,which have been widely demonstrated in wavefront engineering,creation of new optical components,and sensitive optical metrolog y.In this work,we propose and experimentally demonstrate a new type of spin controlled wavefront shaping metasurface.The proposed geometric phase metasurface is designed by employing the integrated and interleaved structures to independently control the left and right-handed spin components.As an exemplary demonstration,our experimental results show that such a composite metasurface can convert a plane wave into a vortex beam and a Hermite beam for left-handed and right-handed polarized light,respectively.Because such metasurface is made by non-resonance dielectric structures,it can work for broadband frequencies with very low dispersion.The proposed metasurface is fabricated by the laser writing method in a transparent glass with a low-cost,which avoids the typical high-resolution lithography process.This spin dependent broadband wavefront shaping metasurface may find potential applications in optical communications,information processing,and optical metrology.4.Optical edge detection is a useful method for characterizing boundaries,which is also in the forefront of image processing for object detection.As the field of metamaterials and metasurface is growing fast in an effort to miniaturize optical devices at unprecedented scales,experimental realization of optical edge detection with metamaterials remains a challenge and lags behind theoretical proposals.Here,we propose a mechanism of edge detection based on a Pancharatnam –Berry-phase metasurface.We experimentally demonstrated broadband edge detection using designed dielectric metasurfaces with high optical efficiency.The metasurfaces were fabricated by scanning a focused laser beam inside glass substrate and can be easily integrated with traditional optical components.The proposed edg edetection mechanism may find important applications in image processing,high-contrast microscopy,and real-time object detection on compact optical platforms such as mobile phones and smart cameras...