Quantum well based devices has been widely investigated in the recent years to be exploted as detectors in the infrared spectrum of light. Many advantages with respect to standard IR detection devices could be achieved, as examples the easy tunability of the detection wavelength related to the geometry of the device and the possibility to work at high frequency. The thesis work is mainly focused on detection of light, through 1D confined quantum systems, semiconductors quantum wells. The device characterized is a quantum well infrared photodetector, made of Ga0.47In0.53As/(Ga0.47In0.53As)0.5 − (Al0.48In0.52As)0.5 lattice matched to InP : Fe substrate, working in the mid-Infrared spectrum (9µm).