Research On Optical Symmetries And Optical Transport Effects In Complex Media Structures

The study of transmission and scattering of light in complicated optical media has emerged as a scientific breakthrough that is profoundly vital for the advancement of new optoelectronic devices at micro and nano levels,as well as being closely related to national interests.Innhomogeneous and anisotropic optical media exhibit an assortment of optical spin-orbit coupling effects,gauge transformation symmetry,while optical systems that involve gain-loss possess parity-time(PT)symmetry and symmetry-breaking phenomena.Bianisotropic optical systems enable the realization of optical topological edge states and valley degrees of freedom.These new principles and concepts are incorporated into various devices,including PT symmetric lasers,topological photonic devices,bound state in the continuum(BIC)lasers,chiral quantum optoelectronic devices,and spin photonic devices.Theoretical modeling and numerical simulation of light transmission and scattering in complex optical media present significant challenges.Firstly,the geometric phase method contained in the optical Magnus effect cannot accurately describe beam transmission in inhomogeneous anisotropic mesoscopic media,leading to complexity in the physical picture.Secondly,optical systems with gain-loss and gyrotropic media are no longer Hermitian,meaning that theoretical models based on Hermitian(energy conservation)principles cannot work well.Thirdly,complex optical systems require the calculation of transmission phase and vector field of light.The complexity of structure,the existence of anisotropy,and complex boundary conditions limit the accuracy and efficiency of simulation calculations,and the calculation amount rapidly increases as the geometric size increases.This thesis aims to address the aforementioned challenges by introducing the symmetry principle and focusing on the symmetry characteristics and related physical effects in complex optical media.Specifically,the thesis investigates the spatial and non-spatial symmetries in complex optical waveguides,the spatial symmetry group in optical scatterers,the hidden symmetry in layer-stacked anisotropic photonic crystals,and the gauge symmetry in two-dimensional(2D)complex media platforms.The investigation highlights the importance of symmetry analysis in complex optical media.The main research findings of this thesis are summarized as follows:First,the paper analyzes the mode relations in anisotropic,bi-anisotropic,and gain and loss waveguide structures.A Hamiltonian is constructed to study the effects of chirality,time inversion,space inversion,parity-time,rotation,and mirror symmetry in complex media waveguide structures.The paper also examines the degeneracy of propagation modes.This provides a theoretical basis for the mode coupling theory and is beneficial for achieving unidirectional propagation in complex media waveguides.Second,this paper studies the effect of symmetry constraints on the decomposition of electromagnetic multipoles in optical scatters.Using group theory,the symmetries of the scattering mode are related to the generating function of the electromagnetic multipoles.By examining the constraints of symmetries on the generating function,the coefficients of expansion for electromagnetic multipoles are obtained.This provides a new solution for theoretical analysis and numerical calculations for optical scattering in complex structures.It can also be applied to reverse the design of complex scattering structures.Third,this paper studies hidden symmetries present outside the structure’s space group in stacked anisotropic photonic crystals.These hidden symmetries improve the system’s degeneracy.Near the enforced triple degeneracy point resulting from the hidden symmetry,two exotic effects on photonic transmission are implied: spin-1 canonical refraction and angle-dependent perfect-tunneling effect.This work expands the scope of research on symmetries in optical systems and promotes research on topological effects in complex periodic media structures.Finally,this paper introduces the gauge transformation in 2D optical platforms.The problem of photonic transmission in complex optical materials is then shown to be analogous to the dynamics of particles in non-Abelian gauge fields.Specifically,light beams are analogous to particles,light polarization is equivalent to particle spin,and the interaction of light and matter in complex materials is equivalent to the gauge field influencing spin.Based on these analogies,the emergence of Zitterbewegung(ZB)and the non-Abelian Aharonov-Bohm(A-B)effect in optics are predicted to occur.This work proposes a new method for understanding light transmission and spin-orbit coupling in complex materials,which is useful in solving problems with beam manipulation.This thesis uses the symmetry principle to study the transmission and scattering of light in complex systems.The methodology and important findings are of great significance in elucidating the optical mechanisms and manipulating light in complex systems.Additionally,this work lays the theoretical groundwork for the development and applications of new optoelectronic technology.