Study on beam energy and impact on communication quality in space optical communications

The beam energy is one of the important factors that affect space optical communications. The beam energy has a direct effect on communication link distance, detector SNR, communication BER and other parameters. To test and verify the related technologies in the space optical communications, the paper proposes a near-earth demonstration and verification experiment systems of emission and detection to the near-space optical communications, which have wavelength of 810nm-band, optical output power of 250mW, modulation ratio of 500Mbps, and achieve to link distance of 8-10 km and communication BER better than 10^-8; analyzes the effect of collimator, electro-optic modulators and optical antenna elements on the beam power loss, beam diameter, divergence angle and other parameters in the system. Theoretical analysis and experimental results are basically consistent; the conclusions have great value on further research of the near-space and deep-space optical communications.