The process of multiwavelengh detection by a single system is possible when
considering multilevel structures. Indeed, in a quantum structure with
specific profile, levels can be confined in a single band leading to
Infrared intersubband transitions which may be responsible of strong enough
absorption. In this work we present the theoretical determination of the
absorption spectra in a specific GaAs/AlGaAs superlattice containing four
confined minibands. For this, we have calculated the electronic states, the
dipole matrix elements and the Fermi level's position versus temperature and
doping. We analyze the importance of the different transitions absorption
peaks and their behavior when varying either the temperature or the free
electrons density, both in the parabolic and the non parabolic cases.