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Acquiring,tracking and pointing(ATP) technique in a 100 km quantum entanglement distribution experiment was introduced in detail.By taking a 700 mm telescope at Alice receiving terminal as an example,the technological specification,light path layout,and tracking accuracy of the ATP system were analyzed.In order to reduce the angle-of-arrival fluctuations of quantum information transmission beams and beacon beams caused by air turbulence,a cascade acquisition and tracking system with coarse tracking,fine tracking and a ultra-fine loop was designed and a dual fast-steering mirror tracking algorithm was proposed.On the basis of a higher frame frequency CMOS detector and a piezoelectric fast-steering mirror,the ultra-fine tracking circuit was developed.Experiments show that these methods solve the contradiction between tracking dynamic range and tracking accuracy,promote the performance of the detector and improve band width and tracking accuracy.The system was used in a ground 100 km quantum entanglement distribution experiment and the results indicate that the tracking error of the system is 4 μrad for a 70 Hz bandwidth.

The light-propagation ability of fiber depends mostly on fiber diameter. Fibers with a diameter below 200 nm have poor capability of exhibiting light coupling and laser radiation. Therefore, we modified nanofibers with a diameter of 150 nm by nanoparticle doping and morphological modification to enhance scattering. A finite-difference time-domain method was used to analyze the coupling of light into fibers and its possible distribution. The simulations demonstrated that single and multiple modes were highly influenced by the diameter values. The results of the study contribute to the realization of random lasers in nanofibers with extremely small diameters.