Coherence Structure Engineering And Its Application In Optical Imaging And Image Transmission

Laser light is one of the greatest inventions in the 20 th century and has found a wide variety of applications.The novel structured light can be generated by modulating the amplitude,phase,polarization,and other degrees of freedom of light field.The traditional light field manipulation is limited to high spatial and temporal coherence laser,it is found that the one with high coherence will induce some negative effects.Decreasing the coherence appropriately,i.e.,partially coherent beam(PCB),can not only keep the original features of laser beam,but reduce many negative effects caused by high coherence.On the other hand,the light field with prescribed coherence structures can show unique advantages in novel structure light generation,propagation,and application.Coherence,including coherence width and coherence structure,as a fundamental resource in all areas of optical physics,plays a vital role in overcome the side effect of turbulence,reduce the speckle noise,improve imaging signal-to-noise ratio,reduce bit error rate of optical communication,and other fundamental fields.Optical coherence enriches the scope of light field manipulation,and has widely used in a variety of application fields.Therefore,the research of optical coherence engineering and its applications has great significance.This research mainly focuses on the construction,transmission,imaging,and image transmission of structed light with a novel coherence structure,by joint manipulating the coherence,amplitude,phase,polarization,and other degree of freedom.Firstly,a new kind of structured light beams has been constructed.The scalar Laguerre Gaussian-correlated Schell-model beam with a twist phase and the Cosine Gaussian-correlated Schell-model beam with a cross phase,etc.,the important role of coherent structure and twisted /cross phase in controlling the beam properties and propagation is discussed.In the vector case,the structured light with a novel polarization state has generated in theory and experiment,named higher-order Poincare sphere beam array,the beam properties induced by the coherent structure and polarization are studied in detail.Secondly,based on the joint manipulation of the coherence and the twisted phase,the propagation characteristics of the twisted PCB in the ocean turbulent medium are studied,and the robustness of the joint manipulation of the phase and the coherent structure in resistance to the disturbance induced by the ocean turbulence is discussed in detail.At the same time,as a basic application of the coherence of the optical field,the application of ghost imaging with the twisted PCB as the illumination are studied,and the important research value of novel structured light in realizing optical imaging and information transmission in complex environment is analyzed.Then,compared to the first-order deterministic parameters,the coherent structure,as the second-order statistical property of the light field,provides a new way for image loading and recovery.Based on generalized Van-Cittert Zernike theorem,a new strategy for optical image encryption and decryption is realized by introducing key parameters into the optical system,such as the optical system in the form of fractional Fourier transform,the fractional order can be seen as a key.However,coherent structure variance with far-field propagation,which limits their application in far field image transmission and encryption and decryption.Therefore,it is an urgent scientific problem to study how to realize optical image transmission with coherence engineering.Based on the above,we proposed a new scheme for the far-field image transmission via coherence engineering.The specific scheme is as follows: loading the image information into the complex coherence structure of the light field;To manipulation the coherence structure far-field transmission invariance,and then transmit it to the far-field;the image information recovered from the far-field complex coherent structure.Based on the multi-degree of freedom manipulation of the light field and the strong ability of the PCB to resistance the disturbance of the complex environment,the robustness of the far-field image transmission in the complex environment(such as atmospheric turbulence,opaque obstacles)with coherence engineering is also studied.