Amplification of gain-switched pulses in semiconductor optical amplifier

We investigated the amplification of picosecond gain-switched laser diode (ps-GSLD) pulses using a semiconductor optical amplifier (SOA). Amplified pulses were characterized using a conventional sampling oscilloscope and an up-conversion time microscope. While sampling measurements showed apparent pulse broadening with increasing SOA current, the time-microscope measurement resolved sub-picosecond main and sub-pulses and revealed their intrinsic gain and saturation behavior. These results demonstrate that the observed pulse broadening originates from measurement limitations rather than intrinsic temporal distortion, and that SOAs can amplify ps-GSLD pulses without distortion when operated in the linear regime.