Polarization-independent δ-strained semiconductor optical amplifiers: a tight-binding study

We present a tight-binding analysis of the polarization dependence of GaAs δ-strained semiconductors optical amplifiers. Our approach allows us to account for band nonparabolicity, valence band mixing, as well as thin layer perturbations, overcoming the natural limitations of standard techniques based on the envelope function formalism. We explain how thin strained GaAs layers embedded in a lattice-matched InGaAsP-InGaAs quantum well can he used to achieve polarization-insensitive optical amplification. The theory is also applied to other structures providing optical amplification, showing how the concept of “virtual barriers” can lead to high polarization insensitivity