System and method for suppressing optical noise of continuous wave all-fiber coherent Doppler laser speed measuring radar

Abstract

The invention belongs to the technical field of laser velocity measurement radars, and particularly relates to a system for suppressing optical noise of a continuous wave all-fiber coherent Doppler laser velocity measurement radar. A 1 / 4 wave plate and a fiber polarization beam splitter are adopted to realize rotation and screening of echo signal light polarization states. The APC end face of thesecond port of an optical fiber circulator or a polarization beam splitter is coated to reduce end face reflection, so that interference is reduced; the invention further provides a suppression methodbased on the system; and thus, additional noise caused by leakage light of the end face of an optical fiber and the port of the circulator in the continuous wave all-fiber laser coherent Doppler velocity measurement radar is reduced, the signal-to-noise ratio is increased, and the detection precision of the system is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of laser speed measuring radar, and in particular relates to a system and method for suppressing optical noise of continuous wave all-fiber coherent Doppler laser speed measuring radar. Background technique [0002] In recent years, laser speed radar technology has made great progress. Specific application fields include laser wind measurement, laser liquid speed measurement, and laser radar for unmanned driving. To achieve the above functions, the widely used technical basis includes Doppler velocity measurement technology, optical coherent measurement technology and all-fiber optical path structure. Among them, the Doppler speed measurement technology is based on the principle that the relative motion of the light source and the target produces a laser frequency shift, and the relative motion speed of the target and the light source is obtained by measuring the movement of the laser frequency; optical cohe...

AI Technical Summary

Problems solved by technology

The PC end of port 2 of the circulator is coated with an anti-reflection coating (<0.25%) to obtain local oscillator light with a suitable power. In this solution, the local oscillator light has been mixed with the signal light in advance and returned from the same optical path, so it is difficult to adopt The balanced detection scheme reduces the optical intensity noise caused by strong local oscillator light, which affects the further improvement of the system signal-to-noise ratio

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