Multiwavelength fiber ring lasing by use of a semiconductor optical amplifier

A multiwavelength fiber ring laser obtained by use of a semiconductor optical amplifier (SOA) with a simple laser cavity configuration is reported. A Fabry-Perot filter was used in the fiber laser ring cavity to achieve more than 50 simultaneous wavelength lasing oscillations with a frequency separation of 50 GHz. The resulting stable broadband multiwavelength lasing operation was attributed to broadband and flat gain of the SOA, which has a gain flatness of 0.8 dB for more than 20 nm. The laser has a total output power of -3 dBm and a signal-to-spontaneous-noise ratio of 30 dB.