Analysis And Manufacturing Investigation Of Polarization-maintaining Fiber Coupler

Because of the coherent sensors such as fiber optic gyroscope and fiber-optichydrophone are used more and more widely in military and civilian areas, increasingly highdemand on their performance. Among them, the optical fiber coupler is the core component ofthe fiber optic sensor. Its performance has a great impact on the overall performance of thefiber optic sensor. At present, optical fiber coupler is mainly made of single-mode opticalfiber in the domestic. Its fabrication process is simple and low cost. However, because it can’tmaintain the polarization properties, the birefringence caused by external perturbations willcause zero drift and signal fading of fiber optic sensors, resulting in coupler performancequite unstable. Polarization-maintaining fiber coupler made by polarization maintaining fiberis a special fiber optic coupler. It not only has the same properties as common coupler, butalso can maintain the state of polarization of linearly polarized light. However, the westerndeveloped countries had been blockading the technology research of polarization-maintainingfiber coupler on China. So it is of great significance to analyze and researchpolarization-maintaining fiber coupler.For the complexity of polarization-maintaining fiber coupler manufacturing technology,its manufacturing was studied in detail in this paper. Used the multi-station automation fusedbiconical taper system with easier operation and higher efficiency and yield to manufacturepolarization-maintaining fiber coupler. Among the production processes of the polarization-maintaining fiber coupler, the shaft process is the primary key. So the on-axis technologies ofthe type Panda polarization-maintaining fiber were analyzed in detail. The factors affectingthe performance of fiber coupler in manufacturing process was also analyzed.From the optical divide ratio, extinction ratio and additional loss these three aspects,analyzed the performance of polarization-maintaining fiber coupler. Analyzed the temperaturecharacteristics of these parameters by experiments, and then based on LabVIEW andMATLAB softwares, designed a convenient, intuitive, and practical coupler performanceanalysis platform to analyse the performance of coupler in room temperature and changedtemperature. By the experimental analysis, summed up the effect of polarization-maintainingfiber coupler performance variation on optical fiber gyroscope, and selected excellentperformance couplers for optical fiber gyroscope or other equipments.Finally, on the basis of polarization-maintaining optical fiber coupler, studied the fusedtaper wide-band polarization-maintaining optical fiber coupler, expanding the applications of the polarization-maintaining optical fiber coupler. Elaborated the principle of fused-taperbroadband fiber coupler. Tested the performance of the self-made several kinds of broadbandoptical fiber couplers and picked out the the couplers with better performance for fiber opticgyroscope and other equipments. Analyzed and verified theoretically the wavelength flattenedcharacteristics of broadband fiber coupler. Analyzed and compared the expect of the couplinglength on optical divide ratio between common coupler and wideband coupler, pointed outthat the coupling length of wideband coupler couldn’t affect the optical divide ratio. Andverified bandwidth characteristics of wideband coupler through experiment analysis.