Studies On Dynamics Of Optical Beam In Waveguide With Gain And Loss

Recently, the concept of PT-symmetry has been the subject of intense in the field of the optics. One can realize the PT-symmetry by double-channel waveguides with equal gain and loss. In the dissertation, we will introduce the coupled mode theory appropriated for the double-channel waveguides and study the properties and characteristic of dynamics with coupled mode equations. We obtained the various propagation characteristic of the optics in the different parameter regions by combining the analytical solution and numerical simulation. Basing on the obtained consequence, we can understand the concept of PT-symmetry to more and the conclusion can provide theoretical basis for the designing optical devices and controlling optical beam. The main contents are as follows:1) From the Schrodinger equation, we deduced the coupled mode equations describing the double-channel waveguides with gain and loss, then we obtained the coupled mode equations about PT-symmetry and local PT-symmetry using the same method, further more, we analyzing the physical significance of the parameters in the equations. In addition, we found the equal result when we obtained the coupled mode equations about local PT-symmetry using Lagrangian.2) We studied the active PT-symmetry and translated the active PT-symmetry to the PT-symmetry. Then we got the propagation constant by coupled mode equations and found the bifurcation of the propagation constant when exceeded the point of PT-symmetry broken. Moreover, we obtained the relations of the optical intensity and transitivity varying with the propagation distance.3) More general situation was studied, in this case, the gain and loss could be varied. We showed the parameter distributions corresponding to different propagation characteristics.