||D. S. Chemla, D. A. B. Miller and S.
Schmitt-Rink, "Nonlinear Optical Properties of Semiconductor Quantum Wells,"
chapter in "Nonlinear Optical Properties of Semiconductors," ed. H. Haug,
(Academic Press, San Diego, 1988) 83-120.
The concept of excitons has been in
existence for over 50 years, and it is a key concept in the physics of the optical
properties of semiconductors. We shall discuss the physics of excitons and the resulting
linear optical absorption in quantum wells (QWs) before going on to the changes induced by
optically generated exciton and electron-hole pair populations. Finallly, we shall
consider the effects of virtual populations of excitons.