High Stability Er-Doped Superfluorescent Fiber Source Improved by Incorporating Bandpass Filter

A Faraday rotator mirror incorporating a Gaussian bandpass filter was used as the reflected end of an Er-doped superfluorescent fiber source to improve its mean wavelength thermal stability. Several different filters were modeled in this fiber source system, and the optimal central wavelength was chosen to be 1558 nm with the bandwidth of 15 nm. With a Faraday rotator mirror incorporating such a filter in an Er-doped fiber source, the mean wavelength variation was measured to be 8 ppm from -40°C to 60°C . The bandwidth reached 16 nm. The pump power was 70 mW at 974.2 nm and the output power reached 18 mW with 6-m Er-doped fiber.