University of Science & Technology China professor Dou Xiankang research group Xia Haiyun and academician China Academy of Sciences Research Group Pan Jianwei Zhang Qiang, after three years of cooperation, for the first time in the world developed single photon frequency upconversion quantum high power laser pointer radar, the aerosol and atmospheric boundary layer wind field day and night continuous observation, made a series of achievements in the International Journal of optical Optics Letters Optics and Express.

Accurate atmospheric wind field detection is of great significance for numerical weather prediction, climate model improvement, military environment prediction, biochemical gas monitoring, airport wind shear warning and so on. Doppler laser radar is recognized as the best method for remote sensing of atmospheric wind field is global, the World Meteorological Organization listed as one of the most challenging of burning laser pen radar. Researchers can monitor the atmospheric aerosol and wind field, not only to monitor the state of atmospheric pollution, real-time atmospheric pollution sources, but also to predict the formation and evolution of haze.

The primary prerequisite for the application of laser radar is the safety of the human eye. In 2007, the National Center for atmospheric research has reported the work of the human eye safe laser radar with a wavelength of 1.55 microns. The near infrared wavelength single photon energy is only 1.28 * 10-19 Joule, Doppler frequency and relative quantum lidar to detect single photons of 6.67 x 10-10 shift, can achieve 0.1 meters / second precision radial velocity measurement. The traditional view is that only to improve the output power of the 2000mw laser pointer radar and increase the area of the telescope, to improve the laser radar detection signal to noise ratio. Due to the low efficiency and high noise of the laser radar, the laser pulse energy is 0.125 J, and the telescope is 0.4 meters in diameter, which leads to complex structure, several tons of weight and large power consumption. Due to the limitation of the optical damage threshold and the processing technology of the large aperture telescope, the performance of the traditional laser radar has reached its peak.

April 2015, China, the first time to achieve a single photon frequency conversion of aerosol laser radar. The use of periodically poled lithium niobate waveguide developed, the radar receiving 1.55 micron and 2 micron continuous single photon pumping and frequency, to produce 0.863 micron photon detection using silicon detector. At this point, the quantum efficiency of up to 55%, dark noise only 16 / sec. Compared with the current indium gallium arsenic detector which is used in the direct detection of 1.55 micron photon (quantum efficiency 10%, dark noise 5000 / sec), the detection efficiency is improved, and the system noise is reduced. This method immediately aroused the attention of the German Aerospace Bureau, Technical University of Denmark, Belarus National University and other peer, in March 2016 using the same technology to achieve atmospheric carbon dioxide detection.

In August 2016, China, using all fiber polarization discriminator of single photon frequency shift was measured by weak light source (laser pulse energy of 5 x 10-5 joule), small caliber telescope (0.08 m diameter) for the first time in the world to achieve the detection of the atmospheric boundary layer wind field. In November 2016, using time division multiplexing, China, reports the current highest integrated quantum 500mw laser pointer radar, not only simplifies the system structure, but also improves the stability and reliability of the system, and from periodic calibration.

By improving the quantum efficiency (photoelectric conversion efficiency) and optical integration (optical system efficiency), suppression detection noise, realize all fiber laser radar system and partial structure of continuous observation, day and night light and small vibration, low power consumption, room temperature operation, suitable for operation in airborne, Shipborne Satellite, etc. the platform under harsh environment. This technique provides a new idea for the small satellite borne 50mw laser pointer radar, which lays the foundation for the popularization of high performance price ratio, high stability and miniaturization.

http://prsync.es/haitianli/laser-radar-to-explore-mars-life-57755/

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