Bidirectionally pumped spectrum-presliced multiwavelength fiber source with a double-pass Mach-Zehnder interferometer

A bidirectionally pumped spectrum-presliced multiwavelength fiber source is presented. Two 980-nm laser diodes are engaged to pump a section of erbium-doped fiber (EDF) in contrary directions. A double-pass Mach-Zehnder comb filter is utilized to filter and reflect the amplified spontaneous emission at one port of the EDF. An optical isolator is employed to guide out the multiwavelength outputs at the other end. The extinction ratio of the source is larger than 24.5 dB over the whole C band, and almost reaches 29 dB at 1530 nm. The integrated power of each channel is 0.58 mW at 1550 nm at 112.3-mW total pump power. The channel spacing and bandwidth are 0.81 and 0.30 nm, respectively. The ratio of the forward pump power to the total pump power is best set between 0.3 and 0.4, to obtain large extinction ratio and high output power simultaneously. The source is expected to have applications in wavelength-division-multiplexing local access networks integrated optics.