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Dual-frequency Doppler lidar for wind detection with a superconducting nanowire single-photon detector
Abstract:
A dual-frequency direct detection Doppler lidar is demonstrated using a superconducting nanowire single-photon detector (SNSPD) at 1.5 μm. The so-called double-edge technique is implemented by using a dual-frequency laser pulse, rather than using a double-channel Fabry–Perot interferometer. Such a modification to the reported lidars enhances the frequency stability in the system level. Using the time-division multiplexing method, only one piece of SNSPD is used in the optical receiver, making the system simplified and robust. The SNSPD is adopted to enhance the temporal resolution since it offers merits of high quantum efficiency, low dark count noise, no after-pulsing probability, and a high maximum count rate. Two telescopes that point westward and northward at a zenith angle of 30° are used to detect the line-of-sight wind components, which are used to synthesize the horizontal wind profile. Horizontal wind profiles up to an altitude of about 2.7 km are calculated with vertical spatial/temporal resolution of 10 m/10 s. Wind dynamic evolution and vertical wind shears are observed clearly.
Fig. 1. Double-edge technique that adopts (a) a double-channel FPI and (b) a dual-frequency laser pulse.
Fig. 2. Schematic setup of the Doppler lidar. OS, optical switch; AOM, acousto-opticmodulator; TA, tunable attenuator; EOM, electrooptic modulator; EDFA, erbium-doped fiber amplifier; FBG, fiber Bragg grating; OS, optical switcher; IF, interference filter; FPI, Fabry–Perot interferometer; SNSPD, superconducting nanowire singlephoton detector; AMP, amplifier; MCS, multi-channel scaler.
Fig. 3. One-hour observation results, from top to bottom: zonal wind, meridional wind, horizontal wind speed, and wind direction.
