Abstract: Double-pass forward and double-pass backward erbium-doped super-fluorescent fiber sources (EDSFSs) were combined in one configuration. A 980 nm laser diode pumped the same erbium-doped fiber from both directions using a coupler as a power splitter. The double-pass configuration was achieved by coating the fiber end face. Firstly, an optimal fiber length was found to obtain a high stability of output light wavelength with pump power, and then 1530/1550 nm wavelength division multiplexing was used for spectrum planarization, which expanded the bandwidth to more than 22 nm. The final step was a test of temperature stability. The results show that the rate of the central wavelength change kept to below 3.5 ppm/℃ in the range of -40 to 60 ℃ and 1-2 ppm/℃ in the range of 20-30 ℃. Considering all the three factors of the fiber optic gyro applications, we selected 80 mA as the pump current, in which case the central wavelength temperature instability was calculated as 2.70 ppm/℃, 3 dB bandwidth 22.85 nm, spectral flatness 0.2 dB, output power 5.17 mW and power efficiency up to 9.92%. This experimental result has a significant reference value to the selection of devices and proper design of ED-SFSs for the application of high-precision fiber optic gyroscopes.

Key words: erbium-doped super-fluorescent fiber source