Free-space communication based on quantum cascade laser

A free-space communication based on a mid-infrared quantum cascade laser （QCL） is presented. A room-temperature continuous-wave distributed-feedback （DFB） QCL combined with a mid-infrared detector com- prise the basic unit of the communication system. Sinusoidal signals at a highest frequency of 40 MHz and modu- lated video signals with a carrier frequency of 30 MHz were successfully transmitted with this experimental setup. Our research has provided a proof-of-concept demonstration of space optical communication application with QCL. The highest operation frequency of our setup was determined by the circuit-limited modulation bandwidth. A high performance communication system can be obtained with improved modulation circuit system.