L-band all-optical gain-clamped EDFA by utilizing C-band backward ASE

By using an optical circulator and C/L-band wavelength division multiplexer to recycle the C-band backward ASE, an L-band gain-clamped erbium-doped fiber amplifier is presented. We have experimentally studied the static gain clamping property of this amplifier. As the ASE feedback attenuation is set to 0, the gain at 1585 nm can be clamped at 18.84 ± 0.26 dB within dynamic range of 25 dB and the critical power reaches about −15.09 dBm. The gain variation and saturated output power at 1585 nm for 0 dB attenuation are 1 dB lower and 2.17 dB higher than those for 30 dB attenuation, which indicates that the L-band EDFA gain can be effectively clamped via the ASE injection technique.