The Study Of Tunable Narrowband Filter Based On EDFA

Erbium-Doped Fiber Amplifier (EDFA) plays an important role in the optical fiber communication system, so more and more studies on EDFA have been done. Under general application, EDFA amplifies the signal power by injecting high pump power in the most of the time. However, a kind of saturable absorption effect has been introduced in unpumped EDFA based on the absorption of the Erbium system which means a lower absorption coefficient in higher intensity. Unpumped EDFA has been widely used as a key component in mode-locked in plenty of fiber laser cavity experiments.Using the available research result for reference, a standing-wave has been introduced in the unpumped EDFA. With the characteristic of the standing-wave, the refractive index of the erbium-doped fiber which connects to the absorption coefficient could be modulated periodically, and a dynamic fiber Bragg grating filter created in the EDF. The bandwidth of the grating is determined by the length of the grating which is based on the input weak pump power in this research.The main contents in this thesis include as follows:(1) Based on the widely learning of many references, theories, construction, basic functions and related propagation and rate equation of EDFA are addressed.(2) The related specialities of the saturable absorber which based on EDFA has been researched And the theory model of the EDFA filter with the knowledge of saturable absorption has been established.(3) We analyzed the bandwidth adjustable method of the EDFA filter using tunable weak pump power in details. Simulation has been made to describe the relationship between the variety of the pump power and the reflection spectra.(4) We also present the numerical simulation of the influencing factor such as Er ion population, the selection of the pump source including the pump power and the pump wavelength to the performance of the EDFA reflection filter with thorough analysis.