Rise Time and Gain Fluctuations of an Electrooptical Amplified Switch Based on Multipulse Injection in Semiconductor Optical Amplifiers

Subnanosecond electrooptical switching times with 26-dB extinction ratio were obtained by using semiconductor optical amplifiers driven by a multipulse injection current. The multipulse switching current was generated by superimposing fast electronic pulse signals in a microwave resistive combiner. Although very fast switching is achievable, nonlinear behavior and circuits parasitic induce gain fluctuations and overshooting during the off–on process. Theoretical and experimental results show that the reduction of parasitics is an important parameter for improving the switching performance. The multipulse injection technique can improve the switching speed for a chosen degree of overshoot.