Analysis of absorption and amplification in a unipolar semiconductor structure with quantum dots

The allowed intraband optical transitions in a quantum dot are considered in the context of their application in quantum-well IR detectors and unipolar semiconductor lasers. The atom-like quantum dot is described by using the harmonic oscillator model. An expression is obtained for the absorption cross section which is independent of the wavelength and the quantum-dot size. Optical absorption and amplification are estimated.