Research On Wavelength Demodulation System Scheme Based On Modular Interference Of Highly Birefrigent Photonic Crystal Fiber

Recently, photonic crystal fiber (PCF) has been more and more concered at homeand abroad in optical fiber devices and optical fiber sensing field, which has become anew research direction in fiber sensing. Compared with the conventional polarizationmaintaining fiber (PMF), highly birefringent PCF (HB-PCF) has many advantages, andhas a wide range of applications in optical fiber sensing field.This paper mainly researches the modular interference and wavelength responsecharacteristic of HB-PCF. Which introduceed mode properties andLP01andLPe11modular interference theory of HB-PCF, and researched modular interference sensingprinciple of the phase difference change of HB-PCF caused by wavelength changes, then,gave concept and characteristics analysis of wavelength response, finally designed aBragg grating’s wavelength demodulation system scheme based on modular interferencetheory.of HB-PCF. The main contents are as follows:Firstly, using finite-element method, the mode properties of two-hole PCF,near-rectangle PCF and hexagonal core PCF are analyzed. In detail, mode fielddistribution, mode field radius concept, and the dependence of modal birefringence andcut-off wavelength of guided modes on the wavelength are discussed.Secondly, the modular interference characteristics of elliptical core PMF, two-holePCF and near-rectangle PCF are simulated. Interference mode field distribution andmodular interference sensitivity properties on wavelength of three type PMF arecompared.Thirdly, the influence of changing type and structural parameters of PMF to therelationship between wavelength and propagation constant difference are analyzed, thenthe introduction of the concept of wavelength response are presented, when therelationship between phase difference and interference sidelobe peak light intensitydifference is monotonic, wavelength response characteristic was analyzed theoretically.At last, based on modular interference theory and wavelength responsecharacteristic of HB-PCF, the paper designed a bragg grating’s wavelength demodulationsystem scheme of structure more simple, easy to realization, temperature stability better and interference sensitivity higher.