PHENOMENOLOGICAL MODEL FOR THE OPTICAL-PROPERTIES OF SEMICONDUCTOR-DOPED GLASSES

The optical properties of semiconductor-doped glasses are determined by semiconductor crystals with diameters of 3 to 5 nm embedded in a glass matrix. The confinement of charge carriers leads to discrete energy states. The motion of the carriers is described by a Ritz ansatz for the wave function combining properties of free particles in a box with those of bulk excitons. In a first approximation the dynamical behavior of the system can be described in analogy to a two-level system. Since each energy level can contain only two pairs strong saturation of absorption occurs. Additionally the size distribution of the crystals is taken into account. It results in an inhomogeneous broadening of the spectral lines that can be described by convoluton of the spectrum with the diameter distribution of the crystals.