Study On Insertion Loss Of Fiber Fabry-perot Filters

Since tunable optical filter is an important device in optical fiber communicationssystem and Fiber Bragg Grating(FBG) sensor system，so more and more attention has beenpaid to it. In optical fiber communication system, tunable optical filters play a vital role inde-multiplexer, optical performance monitoring and so on. In FBG sensor system tunableoptical filers can be adopted in dynamically demodulation. Moreover the applications inoptical fiber ring lasers and microwave photonics of tunable optical filters have drawn muchattentions. Ttunable fiber Fabry-Perot (FFP) filters have the advantages of flexiblestructures, easily tuning, wide tuning range, high finesse and narrow bandwidth. In thisthesis, the insertion loss of tunable FFP filter is studied, methods to reduce insertion loss arediscussed, simulations of an finite-size-mirror fiber Fabry-Perot filter are focused. The maincontents are as follows,(1) This thesis firstly introduces the basic principle of tunable FFP filters. Maincharacteristics including free spectral range, finesse and insertion loss are described.(2) Based on the single-mode fiber coupling loss model, the loss of FFP filters isanalyzed. Owing to the single-mode fiber coupling loss model, methods to decrease insertionloss of FFP filters is analyzed, which provides a theoretical basis to finite-size-mirror fiberFabry-Perot filter.(3) Finite-size-mirror FFP filters are simulated with finite-difference time-domain(FDTD) algorithm. Relations of peak transmittance with the radii of mirror are obtained.Comparisons are made between the optimized structure and full-size-mirror filter, andfiber-inserted filter as well.(4) Effect of cavity length of Fabry-Perot resonator on insertion loss is experimentallystudied.