Multi-wavelength superfluorescent fibre source based on a Mach-Zehnder interferometer

A multi-wavelength fibre source (MWFS) based on a spectrum pre-slicing configuration is demonstrated. A fibre double pass Mach-Zehnder interferometer (MZI), which only consists of three 3 dB couplers, yet has an extinction ratio of larger than 27 dB, has been employed as a reflected comb filter. About 40 channels around 1550 nm with wavelength spacing of ∼0.4 nm has been achieved. The extinction ratio and power variation between channels is larger than 16 dB (limited by the resolution bandwidth of the optical spectrum analyser) and less than 0.5 dB, respectively. Each of the 40 channels has an integral power of ∼0.25 mW without any amplification. Through adjustment of the MZI arm length difference, a multi-wavelength output with other wavelength spacing has also been obtained. This kind of MWFS can be easy fabricated with small volume and should be useful in wavelength-division multiplexing (WDM) systems and integrated optics.