Design And Research Of Optical Add-drop Multiplexer Based On Fiber Gratings

With the rapid development of optical communication network,optical Add-Drop multiplexer(OADM)as the core equipment of all optical communication network,with high cost performance is not sensitive to temperature and polarization,and low insertion loss advantages such as great concern in the communications industry.The principle and performance of cascaded phase shifted linear chirped fiber bragg grating(CPSCFBG)and microring resonator are studied in this paper.Two types of optical interpolation multiplexers are designed and studied.One is the optical add drop multiplexer based on CPSCFBG and Maher interferometer Mach-zinger interferometer.It can finish up and downloading about fifty optical wavelength signals.The other is the new optical add drop multiplexer based on microring resonator and Prague grating.The OADM of this structure can have two downloads,which makes the output channel doubled,so that we can finish the work of downloading multiple wavelength signals.The main tasks are as follows:1.First,the basic principle of optical interpolation multiplexer is briefly analyzed.Then,the structure and working principle of several mature optical add drop multiplexers are introduced.Next,the history and application of fiber bragg grating and microring resonator are described.Then,by studying the theoretical basis of the coupled mode theory(CMT)and the transfer matrix method(TMM),the transmission matrix theory of phase shifted chirped fiber bragg gratings is analyzed.The reflectivity and transmittance of CPSCFBG are obtained.At the same time,the filtering performance of the microloop resonator is discussed systematically.2.A new structure of OADM,that is,OADM based on CPSCFBG and MZI,is proposed.The OADM of this structure is simulated by Matlab simulation software.The OADM is deeply analyzed and studied,with focusing on the 3 important parameters of the grating,such as the chirp,the refractive index modulation depth and the phase shift.Furthermore,multiple groups of values have been obtained to make a clear exploration of the rules of the drop downloader and the output spectrum of the output.In order to improve the communication efficiency and reduce the sidelobe interference.,we optimize the digits by using the cap type function.The output power is about 0.35 and the sidelobe effect is almost zero.And the uniform distribution of the bandwidth is about 50 transmission channels of the output field.3.A new type of OADM is proposed,which is based on the microring resonator and thePrague grating.The OADM of this structure is simulated by Matlab simulation software.The output characteristics of the micro ring resonator(the direct and downloader)are compared before and after the Prague grating is added.Then,the influence of the Prague grating on the filter characteristics of the microring resonator is analyzed.So the OADM output characteristics of the microloop resonator and the Prague grating are analyzed.We have analyzed the structure of the OADM can have two downloads,making the output channel doubling,it can complete the function of downloading multiple wavelengths.