Multiwavelength fiber sources based on double-pass superfluorescent fiber sources

We demonstrate a new technique to generate a high-power multiwavelength fiber source (MWFS) by inserting cascaded long-period fiber gratings (LPFGs) in double-pass Er-doped fiber (EDF) superfluorescent fiber sources. 20 channels with extinction ratios larger than 10 dB can be obtained between 1525-1560 nm with appropriate EDF lengths. Though the total output power decreases due to the insertion of the cascaded LPFGs, the power in each channel for the proposed MWFS is larger than that obtained by using the spectrum slicing technique because of power redistribution. We also demonstrate that by using another LPFG in such a source to reduce the power variation among the desired channels. The wavelength stability of the source is shown to be determined by the cascaded LPFCs rather than by the EDF.