Green's-function approach to the optical nonlinearities in semiconductors and quantum-confined structures

We introduce a method to calculate the linear and nonlinear optical properties of semiconductors and quantum-confined semiconductor structures. The approach is based on a rigorous and simple formula describing the interband density of states, eventually in the presence of a carrier plasma. It allows us to implement numerical algorithms that run faster than previous methods and to write compact analytical expressions. We show analytically that our approach yields the correct optical properties of quantum wells at vanishing plasma densities (two-dimensional Elliott formula).