Study On Propagation Characteristics Of Two-dimensional Photonic Crystal Waveguides Based On FSEM

Photonic crystals usually refer to optical materials that have optical waveguides with discrete or unevenly distributed dielectric structures in the direction of light propagation,and are widely used in optoelectronic components of integrated circuits.Since the 1980 s,more and more photonic crystal researchers have studied and proposed many analytical methods in the field of photonic crystal structure with periodic array distribution.However,there are some problems such as the structure is too simple,the calculation accuracy is not high,the calculation time is too long and the calculation resources are too occupied.Was studied in this paper,using the Fourier series expansion method of two-dimensional periodic chain in combination with perfectly matched layer,three different chain structure model has been proposed,and the computation time is too long and takes up too much computing resources problems,put forward parallel block decomposition method is applied to Fourier series expansion method greatly accelerate the speed of the at the same time avoid the unnecessary waste of computing resources.The main research work is as follows:(1)The two-dimensional elliptic cylinder periodic chain structure,cylinder-elliptic cylinder periodic chain structure and double-layer irregular periodic chain structure are proposed.Firstly,the propagation of light along the long chain of a two-dimensional elliptic rod with infinite period is studied in depth.Due to the uncertainty of the ellipse shape,the propagation characteristics of light will be changed by changing the ratio of the short to the long length of the ellipse.The Bragg propagation period is observed by the variation of the complex propagation constant with the normalized frequency.The waveguide mode,cutoff mode and leakage mode are explained by analyzing the numerical and field distribution of the periodic structure with different proportions.In order to prove the correctness of this method,the numerical comparison with LST method shows that the accuracy of FSEM method is higher.The results also show that with the increase of the proportion,the propagation period of Bragg propagation periodic becomes shorter and a special multi-peak phenomenon appears.In addition,the propagation of electric field is visually demonstrated with 20 dielectric rods chain structures.And then to light along the two-dimensional infinite cycle circle rod-ellipse rod the spread of the long chain of round as the research object,the observations under different conditions of Bragg propagation cycle,the results show that the ratio of the short semi-axis length to the long semi-axis length of different ellipses under the same radius and the same calculation space shows that the larger the ratio,the shorter the Bragg propagation period and the multi-mode phenomenon in the high frequency band.This phenomenon is caused by the uncertainty of the ellipse,so the ellipse structure offers many possibilities.The propagation characteristics of the field distribution in the same Bragg propagation and the next distribution in different computational Spaces are also studied.The results show that the propagation characteristics of the field distribution do not increase or decrease with the change of computational space.In the same Bragg propagation period,the propagation direction and propagation characteristics are the same.Finally,the propagation of light along an infinite period two-dimensional large round rod-small round rod bilayer long chain is studied,and the propagation characteristics of the bilayer regular periodic chain structure are compared with this structure,the results clearly show that the bilayer irregular periodic chain There are only single-even-mode and single-odd-mode state in the structure,while the double-even-mode state occurs in the double-layer regular periodic chain structure at high frequency.The Bragg propagation period and cutoff period of the double-layer irregular periodic chain structure will become longer in the low frequency state,and will become shorter in the high frequency state,and the field distribution characteristics are similar.(2)The matrix calculation by applying the parallel block LU decomposition method to the Fourier series expansion method is proposed,and the optimal block size on the server used is64×64,and the mpi programming is added to realize the parallel calculation.Using this method reduces the computing time and solves the problem of wasting computing resources caused by too large computing space.At the same time,the convergence of the four normalized frequencies of the circular periodic chain structure in TE mode and TM mode is calculated.Behavior.It is found that the convergence of the Fourier series expansion method using the perfectly matched layer is very good.