Demultiplexing Device Based On Spatial Transformation Of Cylindrical Vector Beams

In recent years,with the continuous development of information technology,the demand for high-performance computing power has been increasing,showing a trend of increasing by an order of magnitude every four years.However,with the gradual failure of Moore’s law,further improvement of computing power relies on higher speed and efficiency of parallel computing.Currently,the single-mode fiber interconnect inside supercomputers is unable to meet the growing data transmission demands of parallel computing.Therefore,there is an urgent need to develop new multiplexed optical interconnect technologies with high capacity,low latency,and low energy consumption.Vortex light,especially cylindrical vector vortex beam modes,have vector polarization characteristics and mode orthogonality,and possess transmission stability and almost infinite multiplexing degrees of freedom in space.Therefore,they have great potential for application in multiplexed interconnect communication.However,the efficient demultiplexing principle of traditional scalar vortex beams cannot be directly applied to cylindrical vector vortex beams,resulting in a lack of effective solutions for the demultiplexing of cylindrical vector vortex beams,which greatly limits their application in multiplexed communication.This dissertation focuses on the key core technology of mode MUX/DEMUX for free-space short-distance optical interconnect communication,and conducts theoretical derivation,simulation,and experimental verification.Combining with the research foundation of orbital angular momentum control,three technical routes are developed step by step from optical spatial transformation,to study the demultiplexing mechanism and device design of cylindrical vector mode.The research results of this thesis improve the demultiplexing methods and theories of cylindrical vector beams,and have a positive promoting effect on the further application of cylindrical vector beams in the field of optical communication.The main research of this dissertation includes the following parts:1.This study investigates the demultiplexing of cylindrical vector beams for a single device,starting from the Coriolis effect of on-chip photon orbital angular momentum.The study focuses on the 11 orders demultiplexing of cylindrical vector beams with asymmetric geometric phase lens.By decomposing the cylindrical vector beam into orthogonal circularly polarized components,the theoretical analysis of the interaction mechanism between the two orthogonal components and the asymmetric lens is conducted under the paraxial approximation.The demultiplexing process is simulated using self-written program codes.An experimental verification of the demultiplexing of cylindrical vector beams is carried out using a geometric phase lens fabricated using liquid crystal orientation technology,and the results are analyzed and discussed.2.This study investigates the demultiplexing of cylindrical vector beams using optical spiral transformations based on vector response unit devices.Vector response devices are designed using vector diffraction control units that allow independent phase adjustment in orthogonal directions.The mapping transformation of spiral transformations,which exhibits high resolution in orbital angular momentum sorting,is introduced.A transformation scheme is proposed that realizes the opposite coordinate mapping of left-handed circular polarization vortex and right-handed circular polarization vortex components in cylindrical vector beams and is used for their multiplexing.Two types of devices with vector response control,namely,dielectric metasurfaces and geometric phase liquid crystals,are implemented for this scheme.The multiplexing effect of both devices is verified by simulation calculations.The liquid crystal device is further used to perform experiments,where relevant devices are fabricated,and multiple cylindrical vector beam multiplexing communication is demonstrated.3.This study investigates the bi-directional reversible transformation of cylindrical vector beams using multi-phase planar optical field transformation technology,which can be used for both demultiplexing and multiplexing.Firstly,based on pure phase modulation devices,the orbital angular momentum beam demultiplexing on multiple planes is studied and verified,exploring the factors affecting the conversion efficiency of the system,such as symmetry and the influence of the input array.Furthermore,based on anisotropic vector response units,the multi-plane system is adjusted to a vector response transformation system,and an algorithm oriented towards vector wavefront matching is proposed,which can simultaneously achieve wavefront matching for different polarization states in different directions.Based on this,a multi-plane transformation system for cylindrical vector beam multiplexing/demultiplexing is realized,and the system parameters are further optimized using simulated annealing algorithm.Finally,a reflective vectoral response device was designed based on the liquid crystal birefringence effect to achieve the integration and miniaturization of the vectoral multi-plane conversion system.