Nonlinear Multiplexing Holography Based On Orbital Angular Momentum Of Light

Different from photography,holography can restore the amplitude and phase information of an object at the same time,which plays a significant role in three-dimensional imaging.Therefore,holography has remained a hot topic since its invention.In recent years,on one hand,with the rapid development of computer science and technology,a kind of novel computer-generated hologram has emerged;on the other hand,the advent of the information era inevitably expects a hologram to be an information carrier which can realize multi-channel information transmission.Therefore,multiplexing holographic technology becomes a current research hotspot.The invention of laser boosts the development of nonlinear optics.Because of different optical frequencies of light in nonlinear optical processes,nonlinear holography naturally introduces a number of optical frequencies as information channels.However,the wave-mixing theory in nonlinear optics reveals that these channels are coupled with each other,which hinders nonlinear holography from ideal information multiplexing.Based on the study of orbital angular momentum of light and with algorithms proposed in the design of computer-generated holograms,this thesis proposes an orbital angular momentum encoding technique to solve the nonlinear coupling problem in nonlinear holography.Detailed studies are shown as follows.1.As an example,the parametric amplification progress of Laguerre-Gaussian modes is examined to explore the rules in the nonlinear optical progress of light carrying orbital angular momentum.The aim is to amplify a seed OAM light with its radial index to be zero.Then the mathematical model is established,and a significant quantity called overlap integral is introduced,which decides the conversion rule of transverse modes in parametric progress.After the mathematical model is solved,on the one hand,the orbital angular momentum conservation law in parametric progress is verified;on the other hand,a set of rules to decide the conversion of radial index of LG modes in optical parametric amplification is deduced from the results.At the end of this work,a simulation is conducted to show how to implement these rules.2.An orbital angular momentum encoded multi-channel nonlinear multiplexing holography is demonstrated.With infinite dimensions of OAM,a novel nonlinear multiplexing method is proposed in which fundamental wave is encoded by OAM not only to avoid nonlinear coupling between different optical frequencies,but also to enable a single frequency channel to carry information of many images.The obstacle in nonlinear multiplexing holography is then bypassed and the integration level of image information is greatly improved.In addition,an experiment of second harmonic holography display demonstrates the information multiplexing in fundamental wave and second harmonic wave.A discussion on the possibility to apply this method to other fields like multi-color display is also conducted.3.To solve the problem of low integration level and improve the quality of reconstructed images in traditional nonlinear holography with nonlinear photonic crystals,a novel nonlinear photonic crystal encoded by OAM is designed for multi-channel nonlinear holography.We propose a new OAM matching as a supplementary phase matching condition.With electric field poling technique,a multi-channel nonlinear holography display based on nonlinear photonic crystal is firstly realized in second harmonic generation.Its meaning on the research of nonlinear photonic crystals is also illustrated.