Study On The Reconstruction Algorithm Of Fiber Bragg Grating Based On The Discrete Layer-peeling Algorithm

With the development of fiber Bragg grating technology,fabrication of fiber grating with complex refractive index modulation has become possible.The technology application prospect of fiber Bragg grating in the field of communication and optical sensing promotes the research of inverse design and reconstruction of fiber Bragg grating,which has recently attracted many researchers,providing parameters for the direct design and fabrication of fiber Bragg grating devices.The research of this paper is mainly about the reconstruction algorithm of fiber Bragg grating based on the discrete layer-peeling algorithm,and the main work is done as follows:1.The coupled-mode theory,piecewise-uniform transfer matrix method and microwave-network transfer matrix method of fiber Bragg grating are analyzed;Frequency-domain discrete layer-peeling algorithm,time-domain discrete layer-peeling algorithm,genetic algorithm and inverse layer-aggregation algorithm for reconstruction of fiber Bragg grating are programming realized and verified.Several kinds of grating devices widely applied in the field of optical fiber communication are inversely designed and simulated numerically,which include dispersion less band pass filter grating,all-pass phase shift filter grating,multi-channel filter grating,second-order dispersion compensator grating and linear chirped moire fiber Bragg grating.2.The simulation results show that a small number of length points are required to obtain the coupling coefficients of grating using frequency-domain discrete layer-peeling algorithm and time-domain discrete layer-peeling algorithm,and the running time is short.Among them,the frequency-domain discrete layer-peeling algorithm is applicable to the reconstruction of weak reflection grating,the time-domain discrete layer-peeling algorithm is applicable to the reconstruction of gratings with top reflectivity greater than or equal to 99%.In addition,the coupling coefficients of second-order dispersion compensation grating reconstructed using time-domain discrete layer-peeling algorithm are excellent.We optimize coupling coefficients which are calculated using frequency-domain discrete layer-peeling algorithm by genetic algorithm and there is a high conformance between reconstructed reflection spectrum and the target spectrum.3.A linear chirped moire fiber Bragg grating which is single exposure on the basis of the discrete layer-peeling algorithm;The traditional error function is improved in the genetic algorithm,and a new fitness function used to evaluate the excellence of the samples is obtained to get more satisfied coupling coefficients;The grating coupling coefficient is obtained by combining inverse layer-aggregation algorithm with coupled-mode theory.