Continuous-Wave Operation of Semiconductor Optical Amplifier-Based Multiwavelength Tunable Fiber Lasers With 25-GHz Spacing

We demonstrate wide bandwidth operation in a semiconductor optical amplifier (SOA)-based fiber laser with a wavelength spacing of 25 GHz. A broadband multiwavelength filter based on superimposed and chirped fiber Bragg gratings is used for wavelength selection. Three different cavity configurations are presented and compared: 1) a single-SOA standing-wave cavity; 2) a single-SOA ring cavity; and 3) a double-SOA ring cavity. Up to 41 wavelengths are obtained with a signal-to-noise ratio of 35 dB and a wavelength tunability of 10 nm.