Optical fiber detecting device for kilometer-grade measurement distance

Abstract

The invention discloses an optical fiber detecting device for a kilometer-grade measurement distance, which is characterized in that the optical fiber detecting device comprises a swept laser source, a PC module, a linear scanning driving control module, a coupler and a to-be-detected optical fiber. The coupler is provided with a third pin and a fourth pin for coupling. The third pin is connected with a reference signal branch circuit. The fourth pin is connected with a control circuit module. The control circuit module comprises an encoder and a first branch circuit which is serially connected with the encoder. The first branch circuit comprises a first polarizing beam splitter, a first balancing receiver and a first square filter, wherein the first polarizing beam splitter, the first balancing receiver and the first square filter are serially connected. The encoder is connected with the fourth pin. A closed-loop feedback optical phase locked laser frequency sweeping method is utilized. Laser with a linear frequency sweeping range of 60GHz and line width smaller than 10KHz is realized. The optical fiber detecting device can support an optical frequency domain reflector in the kilometer distance range.

Description

technical field [0001] The invention relates to an optical fiber detection device, in particular to an optical fiber detection device for kilometer-level distance measurement. Background technique [0002] The laser line width and scanning frequency range determine the measurable distance range and positioning accuracy of OFDR respectively. The currently reported laser frequency sweeping can be divided into two categories: first, laser internal modulation frequency sweeping. The laser frequency sweep is realized by tuning the parameters of the laser resonator. The main technical bottleneck faced by this frequency sweep method is that the laser line width and the sweep frequency range are mutually restricted. The narrow linewidth laser has a long resonant cavity or a composite cavity, and the mode selection mechanism is complicated, resulting in a limited scanning range and a centimeter-level positioning accuracy; on the contrary, the linewidth of a short-cavity or single-ca...

AI Technical Summary

Problems solved by technology

The technical bottleneck faced by this method is that the frequency sweep range is limited by the frequency sweep range of the microwave driving signal and the bandwidth of the optical modulator.

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