title: Comparison of the characteristics of double-pass erbium-doped superfluorescent fiber sources obtained from different flattening techniques.
abstract: We investigate and compare the characteristics of erbium-doped superfluorescent fiber sources (SFS's) obtained from the use of different flattening techniques in double-pass forward (DPF) and double-pass backward (DPB) configurations. The intrinsic flattening technique consists of optimizing the length of the erbium-doped fiber. The extrinsic flattening methods include the addition of a samarium-doped fiber (SDF) and a fiber-Bragg-grating (FBG) notched filter at the output end separately to shape the SFS spectrum. Although intrinsically flattened DPF and DPB SFS's have a large output power of >34 mW, they are accompanied by an approximately 3-dB ripple. The FBG-flattened DPF and DPB SFS's can achieve a wide linewidth of 35 nm with a small ripple of approximately 1.7 dB and better pump-power-dependent mean-wavelength stability; SDF-flattened DPF and DPB SFS's are inferior because of the SDF's lossy spectrum.
authors.affiliation: Department of Telecommunication Engineering, National Kaohsiung Institute of Marine Technology, 142 Hai-Chuan Road, Kaohsiung 811, Taiwan.
authors.forename: T C
authors.initials: TC
authors.lastname: Liang
authors.forename: Y S
authors.initials: YS
authors.lastname: Lin
authors.forename: Y K
authors.initials: YK
authors.lastname: Chen