Numerical Analysis And Dynamic Characteristic Investigation Of Quantum-well Semiconductor Optical Amplifier

Semiconductor optical amplifier (SOA) has been widely used in all optical signal processing for next generation optical network. Thus the improvement of the dynamic characteristic of carriers inside the device is a key factor that greatly affects the output performance. Since the characteristic is determined by the energy band structure of the active area, a reasonable design of the energy band structure can improve the dynamic characteristic of carriers. Comparing with bulk structures, quantum well have shorter gain recovery time. Calculating the energy band and other important parameters of quantum well is the foundation of acitve area design and dynamic characteristic simulation.Based on introducing the development of quantum-well and its characters, we calculate the band structure of strained quantum-well using k ? p model. In conduction band model, parabolic model is used to simplify the calculation. In valence band model, the 6×6 Luttiger-kohn model is used and the spin-orbit coupling is taken into account. The effective-mass equations are solved exactly by using plane wave expansion method. The effect of the number and period of plane waves used for expansion on the stablility of energy eigenvalues is examined for practical caculation. In practical caculation, the period of plane wave should be large enough to ensure the envelop functions vanish at the boundary; besides, the number of the plane waves should be large enough to ensure the calculation precision. As the number of the plane waves increases,the efficiency of the program reduces. In practice, we set a precision to determine the number of plane waves.Some important parameters, such as gain spectra and linewidth enhancement factor, are deduced and calculated, which are foundation of dynamic simulation of SOA.Using the obtained band structure and wave functions, we get the relationship between gain and wavelength in different strained quantum well. We also discuss the relationship between the amplitude of peak gain, as well as the wavelength it corresponds, and well width as well as strain. Moreover, the relationship between the linewidth enhancement factor and photon energy is discussed.Finally, on the foundation of numerical analysis of quantum well, we simulate the dynamic characteristic of asymmetrical multiple quantum well semiconductor optical amplifier, during which we focus on the effect of carrier transport on the dynamic performance of gain.