Information Processing And Transmission Technology Based On The Orbital Angular Momentum

Theoretically, the orbital angular momentum (OAM) states value for one photonis infinite, and the values vary from negative infinity to positive infinity. Furthermore,different OAM states are mutually orthogonal. Due to these properties, OAM statesattract a lot of attention recently. In this thesis, we do some studies on the applicationof OAM in signal processing and transmission with the characteristics of OAM. Somerelevant research results are the following:First, a multi-user quantum communication scheme, based on the orthogonalityfor different OAM states, is proposed in this thesis. In the scheme, the sender and thereceiver share an entangled pair of OAM states at first; Then each sender’sinformation is modulated to a different OAM state of the photon at the sender, and asuperposition state is obtained for all users’ information to the photon, Thesuperposition state is transmitted in the noiseless quantum channel. At the receiver,one can accurately recover each sender’s information through coincidence countingmeasurements with a designed rule. Numerical simulation and experimental resultsshow that the scheme is feasible.Secondly, we focus on the compressive sensing technology, and a method toconstruct the measurement matrix with channel coding is presented. Which is basedon the parity check matrix of channel coding, obtains the required measurements withsuperior performance of deterministic measurement matrix replacing the conventionalrandom measurement matrix. The results show that, it has the advantages of fasterconstruction, less memory, more easy to implement, and closer to the results obtainedwith the random measurement matrix. Then, the correlation imaging technology basedon compressive sensing is studied, we propose a realization way to solve it withcompressive sensing. In the application of compressive sensing, compared with theoriginal method without compressive sensing, we get10dB improvement in thecorrelation imaging with heat source using different sparse matrix (both discretecosine transform and discrete wavelet transform are used as a sparse matrix image ofthe object), and5dB improvement in the correlation imaging with orbital angular momentum entanglement source using different measurement matrix (normaldistribution of random measurement matrix and deterministic measurement matrixbased on low density parity check codes).Thirdly, the OAM state is inevitably affected by atmospheric turbulence in freespace optical (FSO) communications owing to its spatial distribution in nature.Although the principle of GI system is quite different from FSO communicationsystem, the implementation of each pixel in GI scheme for multiple gray scale objectcan be regarded as a communication link with a special hologram at the transmitterand a particular coincidence measurement at the receiver. The influence of turbulenceon holographic GI can be considered as noise induced by the turbulence aberration ofholographic GI systems. Channel coding could be used to correct errors caused byatmospheric turbulence so as to improve the atmospheric turbulence tolerance inholographic GI system. The results show that the image quality obtained in theproposed scheme is significantly improved.At last, in order to complete the proposed algorithm and program verification, thesetup for the experimental platform of entangled OAM states is introduced. The coreof the device and a series of general-purpose optical components is described, and theentanglement and nonlocality based on entanglement of OAM is verified by the Bellinequality violation experiments and double-slit interference experiment, respectively.