Research On RCWA Method And It's Application In Design Of Photonic Crystal Solar Cells

This paper mainly studies the RCWA method(RCWA:Rigorous Coupled Wave Analysis).The research contents include the theoretical study of RCWA method,simulation in Matlab platform and implementation in FPGA.The main contents of this paper are as follows:Rigorous Coupled Wave Analysis and Plane Wave Expansion method have been derived in detail,which can solve the diffraction efficiency,field distribution of sub-wavelength structures and band structure of photonic crystals.Firstly,summarize the vector diffraction theory method-RCWA method of subwavelength optical devices with periodic structure.Taking the one-dimensional rectangular grating as an example,we use the RCWA method to calculate the diffraction results of any beam on the grating.The accuracy of the results of the RCWA method is limited only by the Fourier series expansion of the incident light characteristic function.Then,two kinds of sub-wavelength gratings with different structures are proposed and programmed according to the RCWA theory method on the matlab platform.We calculate various diffraction conditions caused by different incident angles and different grating structures when TM polarized light is applied to the grating.It is concluded that for the same beam,when the grating parameters are different in structure,the results of the beam transmission show different periodical changes;and when the angle of incidence changes from 0° to 90°,the transmission efficiency of the light also shows periodic.According to the results of grating analysis by RCWA method,the structural parameters of the proposed hemispherical subwavelength grating and the cylindrical subwavelength grating were optimized.After optimization,the light transmission efficiency was effectively increased.Finally,based on the optimized sub-wavelength grating,a silicon thin film solar cell is proposed.By using the RCWA method to calculate and analyze solar cells,a middle layer and a reflective layer were added to the initial solar cell structure,and the structural parameters of the solar cell were adjusted.After continuous analysis and optimization,the overall structure of the solar cell is improved,and a good diffraction result can be obtained when the incident light is TM polarized wave.Due to the slowness of the PC's computational complexity of the grating structure,an attempt was made to use the FPGA platform to design the RCWA algorithm.Then design FFT core.