Dual band infrared/visible quantum well detector and optically pumped intersubband laser

Deals with a detector concept for the simultaneous detection of thermal infrared and visible (or near infrared) light. We use both interband and intersubband transition processes in a quantum well structure for the device operation. Experimental results on both InGaAs/InP and GaAs/AlGaAs structures demonstrate the validity of this concept. The idea of dual band operation of an InGaAs/InP quantum well infrared photodetector (QWIP) is straightforward. A usual QWIP structure with InGaAs wells and InP barriers is used for mid-infrared detection. The second part reports on results ofa newly developed optically pumped intersubband laser. Intersubband transition between confined states in quantum wells is a fully collective phenomenon displaying distinct many-body effects. These effects are seen in an optically pumped intersubband laser.