All-optical Manipulation Of Kerr-nonlinear Optical Waveguides And PT-symmetric Optical Waveguides

All-optical manipulation of optical waveguides is the basis of all-optical communication. In recent years, people mainly focus on two kinds of methods:all-optical manipulatin of nonlinear optical waveguides, and all-optical manipulation of PT-symmetric waveguides. Viewed from the complex refractive index of the material, the two methods manipulate by changing the refractive index distribution and the gain or loss distribution, respectively. This thesis discusses the two methods by taking the double-channel waveguide as an example.This theses mainly involves three parts:1. The all-optical manipulation of Kerr-type nonlinear waveguidesWe choose the Kerr-type nonlinear double-channel waveguide, and solve the optical modes analytically from the nonlinear Schrodinger equation. The result reveals that there exists symmetry-preserving modes and symmetry-breaking modes. Meanwhile, the escape angle can be manipulated effectively by changing the nonlinear coefficient when a Kerr-type nonlinear medium is placed behide the double-channel waveguide.2. The all-optical manipulation of PT-symmetric optical waveguidesWe obtain the optical modes of the PT-symmetric double channel waveguide from the Schrodinger equation and the coupled-mode theory, respectively. The result reveals that there exists a critical point, when the gain or loss coefficient is smaller than the critical point, the propagation constant is real; while the the gain or loss coefficient is larger than the critical point, the propagation constant becomes complex. Besides, we also discuss the nonreciprocal behavior of beam dynamics in the PT-symmetric waveguide with the two methods, respectively.3. Asymmetric optical amplifierBased on the PT-symmetric double-channel waveguide, we design an asymmetric amplifier. Using the property of nonreciprocal behavior, the amplifier can amplify the difference mode effectively while the sum mode attenuates. Meanwhile, the amplifier can also be used as a mode selector. The difference mode can always be obtained from the output port regardless of the input mode.