Compact mid-infrared transmitter and receiver for free-space satellite communications

We demonstrate a compact mid-infrared (MIR) free-space optical transceiver based on packaged, fiber-coupled intracavity difference-frequency generation (DFG) and sum-frequency generation (SFG) modules operating at room temperature. The system achieves stable MIR generation, recovery of modulated signals up to 1.3 Gb/s, and outdoor validation over a 160 m rooftop link. Link stability measurements confirm robust performance and compatibility with silicon/GaAs detectors, overcoming the limitations of conventional infrared photodiodes. Future work includes rooftop high-speed bit error rate testing, drone-based ∼1km demonstrations, and balloon-assisted ∼25km trials, establishing wavelength conversion as a scalable foundation for next-generation, weather-resistant MIR satellite high-throughput communication systems and quantum communications with short-wavelength detectors.