Recently, there is a great deal of interest in applications of intersubband transitions of quantum wells for optoelectronics. In this paper, we will focus on the application of the first order and second order susceptibilities. The use of the global to local transition in asymmetric quantum wells is shown to give rise a high Stark shift of intersubband absorption. A transfer matrix method for calculation of electronic states is used. Using AlGaAs/GaAs quantum wells, intersubband modulators based on this principle have been demonstrated. Both amplitude and phase modulators are possible. For nonlinear optics applications, we will describe another transfer matrix method for analysis of nonlinear optical processes. With these techniques, optimal designs of desired optical properties for quantum wells with arbitrary composition profiles can be performed and the required phase matching condition can be conveniently obtained.