Research On Plasmonic Devices For Vector Vortex Beam

Vortex beams and vector beams possess spatially varied phase front and polarization,which have the potential application in optical communication,quantum entanglement,optical tweezers,microscopy and laser manufacture.Traditional generation and detection schemes for vortex/vector beams rely on bulked optical elements and complicated optical system,which prohibit them from practical application.Surface plasmon polaritons have the capacity of confining electromagnetic wave within sub-wavelength scale,which show potential applications in photonics,bioengineering,chemical engineering and so on.This thesis investigates plasmonic device for on-chip vector vortex beam generation and detection,and explores the application between vector beam and plasmonic devices.The major work and highlights are list below:1.Based on surface plasmon polaritons interference,proposing a vector vortex beam detection scheme for simultaneous spin and orbital angular momentum detection.Previous studies are mainly focused on orbital angular momentum detection,and thoroughly detecting of vector vortices is rarely discussed.The proposed scheme contains two types of metal nano-slit structure,which are designed for spin and orbital angular momentum detection.In this study,the proposed structure has the capacity of detecting vector and scalar vortices with topological charge ?l??3 at communication band.The proposed structure is compatible with both integer and non-integer l,and the value of l can be directly read out from the position of characteristic fringe.The proposed structure has the advantage of realizing nondestructive detection.Besides,the parameters can be adjusted to meet various operation requirements,and the manufacturing tolerance is high.2.Taking zone plate as a reference,proposing a plasmonic in-plane zone-plate for vortex beam detection.According to the imaging theory of zone plate,a focusing model of in-plane zone-plate is established and applied to topological charge detection.In this study,the proposed scheme has the capacity of detecting vortices with topological charge ?l??3.Then,the single-column slits of in-plane zone-plate are further replaced by orthogonal slits array,which enable simultaneous spin and orbital angular momentum detection for vector vortex beams.The proposed sche,me has the advantage of flexible design and high manufacturing tolerance,which can found potential application in on-chip vector vortex beams detection,and quantum entanglement operation.3.Based on surface plasmon polaritons in-plane total internal reflection,proposing a plasmonic lens for azimuthal beams nano-focusing.The proposed structure has various design freedom,which can be optimized for specific wavelength or ultra broadband operation.Except for serving as a standalone device,the proposed lens can combine with other structure and realize simultaneously azimuthal and radial polarization nano-focusing.Besides,the proposed structure has been utilized in the design of a plasmonic liquid refractive index sensor,sensing performance around 1.3RIU to 1.45RIU is investigated.The intensity-interrogation-based sensor is compact and easy to use.The proposed lens is expected to find potential applications in near-field optical energy focusing,near-field imaging and sensing.4.Based on the characteristic of hybrid-order Poincare sphere,proposing a metasurface design scheme for arbitrary vector beam generation.By introducing circularly polarization-dependent lens phase distribution to azimuthal phase modulation,circularly polarized incidences can be converted to the states described by the northern and southern pole of hybrid-order Poincare sphere.Since states on hybrid-order Poincare sphere can be represented by the superposition of two orthogonal state,arbitrary states can be obtained by adjusting incident polarization.