Theoretical and experimental study of multifunction C+L band hybrid fiber amplifiers

• A single-wavelength pump LD is used for pump shaing the C+++L band amplifier.
• Power equalization among channels is realized by optimizing the FBGs reflectivity.
• A pump reflector is used to recycle the residual pumping power.
• Optimum dispersion compensation the individual band channels using FBGs.
• Bit error rate performance for C+L band amplifier is experimentally verified.

We proposed and demonstrated a 100 km hybrid C+L band fiber amplifier in the bridge-type scheme. It is composed of a C-band erbium-doped fiber amplifier (EDFA) and an L-band Raman fiber amplifier (RFA) using double-pass dispersion compensators in a loop-back scheme. Dispersion slope mismatch is compensated precisely for all C+L band channels by writing fiber Bragg gratings (FBGs) at appropriate locations. Gain variation among multiple channels can be reduced to ±0.2 dB. The pump efficiency is improved by recycling the residual pump power. The C/L band WDM coupler which at merged point rejects C band amplified spontaneous emission (ASE) using L band coupler and vice versa. Both the simulation results and experimental measurements are realized in this paper. The hybrid EDFA/RFA may find vast applications in WDM long-haul systems and optical networks.