Investigation of Amplified Spontaneous Emission in Quantum Dot Semiconductor Optical Amplifier in Presence of Second Excited State

In this paper, amplified spontaneous emission (ASE) in quantum dot semiconductor optical amplifier (QDSOA) is investigated. The presented theoretical model is based on set of rate equations that consider all possible carriers transitions including the second excited state (ES2) transition. These coupled equations are solved numerically. It is illustrated that the obtained ASE spectrum has three peeks which are related to ground, first excited and second excited states. Furthermore, optical gain for 500 fs Gaussian input pulse train is calculated. Based on the results, it is shown that in presence of ES2, gain recovery time and noise figure (NF) are reduced and the QDSOA can be used for ultra-high bit-rate signal processing (up to 450Gbps).