Reflective semiconductor optical amplifier pattern effect compensation with birefringent fiber loop

We experimentally explore and demonstrate the potential of a birefringent fiber loop (BFL) to compensate for the pattern effects (PE) induced in a reflective semiconductor optical amplifier (RSOA), which is driven by optical data whose intensity, temporal and spectral characteristics heavily stress the RSOA. By properly tailoring the BFL comb-like profile and adjusting the relative offset between the BFL maximum transmission and carrier signal position, the BFL improves the RSOA pattern-dependent performance even though the input pulses' modulation bandwidth exceeds the 3 dB cut-off frequency of the RSOA optical response. The extensive set of obtained experimental results confirms the BFL capability to enhance the RSOA operation even under strong saturation, since the BFL acts in a beneficial manner on the amplified pulses by reducing their overshoot to an acceptable level, restoring their spectral position, reshaping their eye diagram and increasing their input power dynamic range. These notable improvements, combined with the construction from off-the-shelf components, straightforward implementation, simplicity of operation and flexibly tunable transmission characteristics, render the BFL an attractive solution for efficiently combating the RSOA PE and resolving its undesirable complications.