Résumé
A free-space optical (FSO) transmission system is experimentally demonstrated in the long-wave infrared (LWIR, 9.15 mu m) using a directly modulated quantum cascade laser (DM-QCL) and a commercial mercury-cadmium-telluride infrared photovoltaic detector. At room temperature, the DMQCL is current-modulated by discrete multitone signals pre-processed with bit-/power-loading. Up to 5.1 Gbit/s data rate is achieved with bit error rate performance below the 6.25% overhead hard-decision forward error correction limit of 4.5 x 10(-3), enabled by a frequency domain equalizer. The stability study of the FSO system is also performed at multiple temperature values. This study can provide a valuable reference for future terrestrial and space communications.