Analysis of gain improvements through a pump reflector in Er/sup 3+/-doped optical amplifiers in the presence of concentration quenching

We numerically examine the small-signal gain improvements possible when the pump light is reflected in erbium-doped amplifiers suffering from concentration quenching caused by homogeneous and inhomogeneous energy-transfer upconversion. For an unquenched amplifier, the improvement is larger for a pump power of 20 mW than it is at 100 mW. On the other hand, at a pump power of 100 mW, the reflector is found to be efficient for a quenched amplifier, with a maximum improvement of 6.5 dB. We also find that the reflector is more efficient at 1.535 μm than it Is at 1.550 μm, under all examined operating conditions.