TECHNION - ISRAEL INST OF TECH HAIFA DEPT OF ELECTRICAL ENGINEERING
Multiple quantum well MQNW optical amplifiers have recently been demonstrated. It has been shown that these MQW amplifiers have excellent characteristics such as high gain, large saturation power and low noise. In addition to being excellent devices, they can serve as convenient tools to study the gain dynamics in an inverted MQW media. The energy band diagram of a typical 1.5 um InGaAsInGaAsP MQW optical amplifier. When an electrical pump DC current is applied to the device, the allowed states of the structure fill up as the quasi Ferni level rises. Since the amplifier never reaches lasing threshold, there is no pinning of the Ferni level which may rise to a level far in the barrier. In that case, the barrier serves as a carrier reservoir 4. When a strong optical pump is injected at an energy level inside the QW, carriers from higher energies relax to the newly generated empty states. Replenishing of the removed carriers comes first from higher energy levels which are inside the QW this process has a sub-ps time constant. Then the carriers in the barriers diffuse towards the QW and are captured with a mean time of several ps 4,5. And finally, conventional recombination dominated by Auger processes, with time constants of - 250 ps take place in the barrier region 4.
This article is from 'OSA Proceedings of the Topical Meeting on Optical Amplifiers and their Applications Held in Snowmass Village, Colorado on 24-26 July 1991. Volume 13,' AD-A252 974, p134 thru p137.