Coherent Optical Time Domain Reflectometer Based on Phase Conjugated Twinlets

Abstract

The present invention provides a coherent optical time-domain reflectometer based on phase-conjugated dual wavelets, including a laser, a 1*2 optical coupler, an acousto-optic modulator, an optical circulator, an OTDR data processing module, a polarization multiplexing modulator, a polarization Multiplexing coherent detector; polarization multiplexing modulator respectively modulates two phase-conjugated COTDR detection electrical signals onto the detection light pulse, and then performs polarization combining on the two modulated orthogonal modulated light information The detection optical signal transmitted on the optical fiber is formed; the polarization multiplexing coherent detector decomposes the optical signal from the detection optical input end into two orthogonal signals, and then coherently mixes with the local oscillator light from the local oscillator optical input end respectively detection, and finally the two optical signals after coherent detection are superimposed and output. The invention improves the dynamic range of the coherent optical time domain reflectometer COTDR, and is suitable for line detection of long-distance optical fiber transmission.

Description

technical field [0001] The invention relates to optical fiber sensing technology, in particular to light detection technology. Background technique [0002] Optical time domain reflectometer OTDR is a kind of optical fiber detection instrument, which is mainly used for the measurement of optical fiber length, optical fiber transmission attenuation, joint attenuation and fault location. The optical time domain reflectometer OTDR detects the Rayleigh scattering generated when the optical pulse is transmitted in the optical fiber and the Fresnel reflection at the fiber break, where the backscattered light returns to the transmitting end after being scattered and reflected, and is captured by the OTDR. The detection pulse used by traditional OTDR is generally a single pulse with a certain width, and the detection method adopts non-coherent detection, which is generally used for the test of short-distance communication lines. However, in thousands or even tens of thousands of ki...

AI Technical Summary

Problems solved by technology

When the frequency of the detection light changes, the heterodyne intermediate frequency between it and the reference light will change. Once the heterodyne intermediate frequency signal falls outside the bandpass filter bandwidth of the system, the power of the signal will be lost, which will increase the slope of the detection curve.

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