Quantum dot vs. GaInNAs/GaAs quantum wells for broad band amplification

There has been a lot of interest in broad band amplifiers required for ultra-fast communications systems where a fast pulse with a wide spectral range is put through fibre. Quantum dot SOAs with inhomogeneous broadening provide broad gain. Different sizes of dots can amplify different wavelengths but their interaction is governed by their homogeneous linewidth. We examine the limitation that this puts on multi-wavelength amplification and examine the effect of barrier height. We consider the quantum well system GaInNAs/GaAs and consider whether local fluctuations within this system can act as localised centres for amplification as in the quantum dots. We examine the controlling parameters for this system and compare and contrast these two systems for use as broad band SOAs.