Research On L-Band And C+L Band Edfa

EDFA has become an indispensable element in optical communication system, especially in DWDM system. C-band EDFA has been mature and commercialized for a long time, but with the rapid growing of Internet and data service, the conventional band can not satisfy the capacity demand. As a result people have begun to utilize long-wavelength band. Research on L-band and C+L band EDFA has been showing ever-increasing importance. In this paper, theoretical and experimental research on L-band and C+L band EDFA was presented.Theoretical:Efforts were given to present a thorough but intelligible exordium of the thesis.The Giles Model , which is most widely used in EDFA's numerical stimulation, was deduced. The characteristics of EDFA's amplified spontaneous emission (ASE) was discussed by using the Giles Model. Aimed at giving an theoretic instruction of utilizing ASE in C+L band EDFA, emphasis was laid on the evolution of forward and backward traveling ASE along the fiber, different shapes of ASE curve and ASE wavelength properties under various pump powers.The evolution of the upper-state population and pump power along the fiber was calculated, while pumped by 980nm LD and 1480nm LD respectively. This can be used to compare the effects of the two pump sources on C-band and L-band EDFA and to propose a prompt combination of both in C+L band EDFA.Experimental:Experimental research on L-band EDFA which was composed of high-concentration erbium-doped fiber was proposed. The influence of Er3+ concentration on L-band EDFA was analyzed. Experimentally investigated the properties of L-band EDFA with C-band seed light injection and 980nm forward pumping. We proved that C-band seed light can promote L-band EDFA's pump conversion efficiency. Gain flattening of L-band EDFA was carried out by utilizing high-birefringence fiber loop mirror. Good results were obtained in both two-stage, medium-concentration EDF based L-band EDFA and single-stage, high-concentration EDF based L-band EDFA.Efficient L-band EDFA based on fiber Bragg grating(FBG) was investigated. The experimentation demonstrated that by incorporating a FBG to reflect part of the backward ASE, additional seed-light source can be eliminated while maintaining similar effect.Experimental investigation on C+L band EDFA with parallel configuration was carried out. Three ways of injecting C-band ASE were tried out and we demonstrated that C-band ASE can be utilized to enhance L-band EDFA's efficiency.