Research On Polarization Filtering Characteristics Of Gold-Filled Square Array Photonic Crystal Fiber

With the advancement and development of science and technology,products tend to be lighter and smaller.In the optical field,the use of photonic crystal fibers to make polarization filters can achieve the purpose of easy integration and small size,and is expected to achieve a significant improvement in performance.This paper uses the finite element method to study the characteristics of the single-window and double-window polarization filters of the gold-filled square array photonic crystal fiber.The main content of the paper is as follows:Firstly,by solving Maxwell’s equations,the transmission characteristics of light waves in optical fibers are given.Using the basic principles of evanescent wave and SPR in optical fiber,the characteristics of SPR effect excitation are described.The coupling theory between the fiber fundamental mode and the surface plasmon mode is introduced in detail.Finally,the finite element method for solving the transmission characteristics of the photonic crystal fiber is introduced,which lays the theoretical foundation for the research of the square array gold-plated photonic crystal fiber polarization filter based on the surface plasmon resonance effect.Secondly,a gold-filled square array photonic crystal fiber single-window polarization filter was simulated,and the dispersion relationship and loss characteristics of the structure were analyzed.Based on the original structure,the influence of each structural parameter on the performance of the filter is studied from three aspects.The optimal structural parameters are obtained by numerical analysis.The optimal structural parameters are obtained by nu-merical analysis.Near the wavelength of 1460 nm,the limiting losses of x and y polarization fundamental modes are 2511.40 d B/m and 16444.67 d B/m,respectively.Finally,a gold-filled square-array photonic crystal fiber double-window polarization filter is proposed.The dispersion relationship and loss characteristics of the structure are analyzed,and the optimal structural parameters are obtained.The limiting losses of the x and y polarization fundamental modes at 1310 nm and 1550 nm wavelengths are 46614.5d B/m and 80711.4 d B/m,respectively.The paper compares the performance of limiting loss,extinction ratio and bandwidth with the reported filters.In addition,it is also analyzed that when the manufacturing tolerance of the gold film thickness t and the air hole d₂changes by 5%,the filter performance is still stable and feasible.