Disscusion Of 2D MPC Circulator And Its Experimental Verification In Microwave Band

Since the motion of photons in photonic crystal can be controlled as will,photonic crystal(PC)is considered to be the core of the future development of photonic devices.Two-dimensional magnetic-photonic crystal circulator is a multi-port non-reciprocal passive device.The circulator can sequentially circulate in forward direction but prevent in reverse direction.In order to reduce the interference and enhance stability of large scale integrated optical circuit,circulator can be used to isolate the reflected light between adjacent modules or devices.Firstly,several analytical methods of two-dimensional(2D)magneto-photonic crystal(MPC)are introduced.The band structure of photonic crystal and the mode field distritution of defect structure can be calculated by the plane wave expansion method.Using the finite element method the wave equation can be transformed into finite element equations,which also will transform electromagnetic field problem in waveguides into the eigenvalues problem and the corresponding eigenfunction problem.Then,the transmission of electromagnetic wave in circulator is solved.Secondly,a three-port Y-junction circulator with a ferrite cylinder is designed by using a defect structure of triangular lattice 2D MPC.The functions and external characteristics of the Y-typed photonic crystal waveguide(PCW)and circulator were simulated and calculated by finite element method.Furthermore,the Y-typed MPC circulator was first successfully developed in the microwave band,whose isolation is up to-61.1dB at the central frequency of 10 GHz.Based on the scaling theory of Maxwell's equations,a circulator using 2D MPC is obtained in microwave band by scaling the size of the 2D MPC defect structure.The 3mm Y-Junction three-port circulator is respectively accomplished based on the structure constructed by air holes or dielectric rods array.Finally,the cross shaped PCW was numerically and experimentally studied based on the square lattice PC.The gyromagnetic ferrite column is introduced into the waveguide junction.The four-port cross-typed MPC circulator was successfully developed for the first time in the microwave band.A three-port T-shaped waveguide circulator based on a defect structure of 2D square-lattice MPC is envisaged.The isolation of the T-shaped circulator is up to-45.2d B,the insertion loss of the circulator is low to-0.88 dB.The excellent external characteristics of the circulator show that 2D MPC circulator has important applications potential in the future integrated optical circuit.