Preliminary demonstration of text and real-time video transmission in free space optical communication system at 2 μm band

A free space optical communication system at 2 μm band was preliminary demonstrated. The fiber laser source is a homemade continuous wave thulium-doped fiber laser with single-wavelength output. The center wavelength of the fiber laser is 2048.15 nm, and the fluctuation of the wavelength and optical power is less than 0.02 nm and 0.893 dB, respectively. By modulating and demodulating the radio frequency signal, the text and real-time video transmission was realized. The transmission distance in free space is ~1 m, and the transmission rate is less than 66 kbit/s. With further improvement, the system may be well suited in free space optical communication system.