A dual-frequency coherent wind lidar based on single-frequency continuous optical EOM modulation

Abstract

The invention discloses a double-frequency coherent wind lidar based on single-frequency continuous light EOM modulation. The double-frequency coherent wind lidar adopts dual-wavelength laser as a light source, and detects difference of dual-wavelength Doppler frequency shifts through coherent beat frequency to invert speed; and meanwhile, Doppler frequency shift information is extracted by adopting a microwave signal, thereby reducing speckle noise due to detection object unevenness and atmosphere turbulence. Besides, two side frequencies are generated through a single-frequency continuous wave EOM modulation method; double-frequency laser is generated through a method of utilizing a filter to filter center light frequency and filter out the two side frequencies; and the double-frequency laser generation method improves stability of a double-frequency gap, and the double-frequency gap can be controlled flexibly by adjusting trigger signals of modulators. According to the scheme, the dual-wavelength laser is obtained through single-frequency continuous wave EOM modulation, the speed is extracted through a microwave mode, and atmosphere wind speed information is inverted; the stability of the double-frequency gap is improved; and the double-frequency coherent wind lidar has the advantages of high detection precision, anti-electromagnetic interference and compact structure and the like.

Description

technical field [0001] The invention relates to the field of laser radar wind measurement, in particular to a dual-frequency continuous optical coherent wind measurement laser radar based on laser modulation. Background technique [0002] Lidar has been widely used in wind measurement, distance measurement, imaging, pollutant monitoring, wind measurement, temperature measurement, etc. and other fields. In the traditional coherent wind lidar, the single-frequency laser is divided into two parts, one is emitted to the detection target, and the other is used as the local oscillator light, and the speed detection of the target is realized through the backscattering signal of the target and the beat frequency of the local oscillator light. . Ideally, when the speed of the target object is constant, the obtained spectrum has a narrow linewidth, and the speed information is extracted from the Doppler frequency shift. However, in actual situations, due to the uneven surface of th...

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Problems solved by technology

In order to obtain dual-frequency laser output, the mode-locked laser needs to be equipped with a wavelength selective switch or a Fabry-Perot interferometer, and the seed-implanted semiconductor laser needs to be equipped with a master laser and a slave laser. Therefore, the optical path of the laser radar system based on these two lasers is complex. , high cost

In addition, the dual-frequency laser source can also be obtained by overlapping two laser beams with known frequency differences or based on laser extracavity modulation, the former obviously cannot improve the problem of low laser coherence

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