Dynamics And Control Of Pt-symmetric Optical Waveguide With Periodical Modulation

Parity-time(PT)symmetric optical waveguide is a novel optical waveguide thathas many unique optical properties.Due to it has important potential application in the photonic information processing and integrated optics,it has been widely investigated recently.In all research on PT-symmetric optical waveguide system,manipulation of the PT-symmetry not only is a basic and important problem,but also is the core content about the control of propagation dynamics of beam.Therefore,the people imminently hope to find a set of convenient and effective method to control the PT-symmetry.In this paper,based on the PT-symmetric less channel optical waveguide,we explore how to manipulation of the PT-symmetry and dynamics of the system by adjusting the external field.The structure of this article is as following:In Chapter 1, we introduce the definition of PT-symmetry and its development in quantum physics and optics.In Chapter 2, we analytically investigate the effect of PT-symmetry on propagation dynamics of optical beam in an optical coupler. The analytical solution of propagation dynamics equation of PT-symmetric optical coupler is given. For unbroken PT-symmetric phase, the light intensity oscillates periodically between two waveguides,whereas light always localize the waveguide experiencing gain regardless of the light is initially inputed from waveguide experiencing gain or loss for broken PT-symmetric phase. These analytical results agree with the recent experimental observation reported by Rüter et al. [Nat. Phys.6(2010) 192]. Furthermore, we also explored how to control the PT-symmetry and propagation dynamics via periodic modulation.In Chapter 3, we investigate the Floquet control of the gain and loss in PT-symmetric optical couplers. We found that the gain and loss can be effectively Floquet control through periodically modulating the coupling strength between the two waveguides. Even an non-Hermitian system can be manipulate to an effective Hermitian system, which corresponds to original non-Hermitian system under the high frequency approximation. Our results show that the unbroken PT-symmetric range can be modulated wide, which is different from the previous results, where the unbroken PT-symmetric range only can be modulated narrow. At the same time, we also explore the tunneling dynamics and optical simulation of the system.In Chapter 4, we further investigate the tunneling dynamics for a periodic modulation non-Hermitian optical quadrimer waveguides. We analytically give the quasienergy spectra of the system under the high-frequency approximation. We found that for quadrimer waveguide without modulation, there do not exist entirely realeigenvalue spectra in certain parameter, but for modulation quadrimer waveguides system, there not only has entirely real eigenvalue spectra, but also the entirely real eigenvalue spectra can be manipulated via periodic modulation. Furthermore, we numerically and analytically explore the tunneling dynamics of the system. It is found that we can control the light tunneling direction in quadrimer waveguides via periodic modulation.In Chapter 5, we briefly summarize our results and give some outlooks.Throughout the whole article, we will explore how to control the PT-symmetry and tunneling dynamics by applying periodic modulation for PT-symmetric less channel optical waveguide. Our main works are involved in chapters 2,3 and 4.