| Optical isolators are the important passive devices for optical communication systems which can prevent unwanted reflection from disturbing the expected function of optical devices such as the lasers and the optical amplifier, and so on.At present, all of the optical isolators are bulk devices in practice. But with the development of optical integrated circuits, integrated optical (IO) isolators are needed. For IO isolators, the research was begun from 1970s, but it is so difficult and complicated that there are no applied devices to date. How to make an actual IO isolator is one of the research focuses.Waveguide optical isolators based on nonreciprocal TE-TM mode conversion are investigated here. It requires in addition to the 50% nonreciprocal mode conversion another 50% reciprocal conversion.The result of wave transporting in the magneto-optical waveguide has been given based on Maxwell equations. The nonreciprocal Faraday Effect and the coupled wave equations are discussed. Finite Difference Beam Propagation Method (FDBPM) is used to solve the coupled wave equations and the program has been finished with MATLAB.The simulation and design of integrated isolator are assumed that the waveguide is buried in SiO2 and the substrate is Si material. The phase relation between the transverse field components is obtained which causes the rotations by the nonreciprocal mode conversion and reciprocal conversion add up to produce a desired 0°or 90°total rotation. Several modeling of integrated isolator are designed with this result and the simulations prove the design to be feasible.The preparation of crystalline Ce:YIG on amorphous silica substrate by RF magnetron sputtering method is discussed in this thesis. For the sputtering process, the temperature of substrate, the sputtering atmosphere, the RF power density and the distance between target and substrate are the key factor to influence quality of thin films. Good thin films will be manufactured by optimizing the sputtering parameters. |
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