The effects of quantum-well number on gain crosstalk in semiconductor optical amplifiers

We report on crosstalk reduction in conventional semiconductor optical amplifiers, obtained by reducing the number of quantum wells in the active region. While the resulting decrease in carrier lifetime is not favorable for improving gain crosstalk (GXT), it is more than compensated for by the simultaneous reduction in gain and increase in saturation power. Experimental results show 2-channel GXT of -20 dB at a modulation frequency of 10 GHz, a fiber-coupled output power of +5 dBm (+2 dBm per channel), and a module gain of 15 dB.