Simulation of Ultrafast Cross-Gain Modulation in Optically-Pumped GaN/AlN Intersubband Optical Amplifiers

Cross-gain modulation (XGM) of sub-picosecond optical pulses in optically-pumped GaN/AlN intersubband optical amplifiers (ISOA) has been analyzed by a one-dimensional finite-difference time-domain (FDTD) model. The calculated signal gain at 1.544 µm was about 20 dB at a pumping power of 6–7 W. A 10-dB gain suppression was predicted at a control pulse energy of 100 fJ. This switching energy is one order of magnitude smaller than that in saturable-absorber switches utilizing the intersubband-transition in GaN/AlN quantum wells. The simulation suggested that the XGM switches operate without serious pattern effect even at 1 Tb/s.