Research On The High Birefringence Photonic Crystal Fiber Loop Mirror Comb Filter

As the main method to expand the capacity of the optical fiber,Dense Wavelength Division Multiplexing (DWDM) technology has attracted more and more attention of the scholars both at home and abroad. And tunable optical filter is one of critical components in DWDM technology. In recent years,the research of various tunable optical filters has become a hot spot. Therefore,in this thesis, a type of comb optical filter based on high birefringence photonic crystal fiber loop mirror is investigated. With the advantages such as polarization-independent, wide wavelength span, stable performance, flexible operation, tunable channel spacing, low polarization mode dispersion , and so on, the filter has been widely used.In this paper, using full-vector finite-element method, the high birefringence characteristics of the photonic crystal fiber (PCF) are theoretical analyzed in detail and numerical simulated. In addition,further researches on output spectrum of high birefringence photonic crystal fiber loop mirror comb filter are taken based on the theory of Jones matrix,which provide theoretical basis for the practical application.The main achievements are as follows:1) A new kind of rectangular lattice photonic crystal fiber with a central elliptical defect hole in the core region is designed. The modal birefringence characteristic is studied using full-vector finite-element method. By simulation, it can been seen that the high modal birefringence of the PCF is 1.87×10^-2 at the wavelength of 1.55μm,which provides a good theoretical model for the polarization maintaining fiber.2) Using the theory of Jones matrix, the output spectral function of the comb filter based on high birefringence photonic crystal fiber loop mirror is derived,and the impact of polarization controller on the output spectrum of the filter is discussed by the MATLAB software simulation.3) The impact of lateral static pressure along the x-axis positive side,y-axis negative side on the transmission spectrum, spectral channel interval and channel spacing of high birefringence photonic crystal fiber loop mirror comb filter is discussed. And the sensitivity, which is different with channel spacing with various pressure of two kinds of PCF filters. By simulation, the optical filter is a kind of optical device with various advantages such as polarization-independent , wide wavelength span, tunable channel spacing, stable performance, low polarization mode dispersion, which could be widely used in the fields of fiber-optic sensing, optical amplifier, DWDM systems and so on.