Terahertz Quantum Well Devices and their Potential for Free Space Communication

We report on our development of both detectors and lasers in the terahertz (THz) region. For detection, we focus on the approach based on the extension of the celebrated quantum well infrared photodetectors (QWIPs); whereas the quantum cascade lasers (QCLs) provide the source. We show our preliminary demonstration of free space communication using our detectors and lasers. An all photonic THz communication link operating at 3.8 THz using a QCL and quantum well photodetector has been demonstrated. The link consists of a quantum cascade laser transmitter and a quantum well photodetector receiver. The link was used to transmit audio through two meters of room air. Carrier strength at the photodetector was 100 times above the noise level measured. THz free space communication may be of interest in satellite based systems.