New method for precisely measuring optical fiber length by adoption of vector network analyzer

Abstract

The invention provides a new method for precisely measuring optical fiber length by adoption of a vector network analyzer. The vector network analyzer is introduced, the phase zero making technology is combined, and therefore the defects that a back scattering method is poor in measuring precision, many in interference factor of a pulse method, short in measuring distance and the like are overcome, and the shortcomings that a traditional phase shifting method is narrow in frequency measuring range of a phase meter and poor in phase measuring stability are overcome; in the long-distance transmission of optical fibers, due to widening of optical pulses caused by optical fiber dispersion, time amount of optical pulse delay is replaced with the phase variable quantity generated by measuring optical signals in transmission in the optical fibers, the accuracy value of the optical fiber length is calculated, and therefore the influence of the optical fiber dispersion on a measuring result of the optical fiber length is reduced.

Description

technical field [0001] The invention belongs to the technical field of measuring the length of an optical fiber, and in particular relates to a new method for accurately measuring the length of an optical fiber by using a vector network analyzer. Background technique [0002] The commonly used optical fiber length measurement methods mainly include backscattering method, pulse method and phase shift method. The backscattering method uses the backscattered light generated by Rayleigh scattering and Fresnel reflection when light is transmitted in the optical fiber. To measure the length of optical fiber, the optical time domain reflectometer developed by using this principle has been widely used in the construction and maintenance of optical fiber communication links. There are many unavoidable factors that cause errors in this method, such as instrument resolution error, optical fiber group refractive index, and backscattering loss coefficient. Therefore, the measurement acc...

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Problems solved by technology

[0005] (1) The measurement accuracy of the optical time domain reflectometer (OTDR) is not high, and can only reach the meter level; while the measurement range of the optical coherent domain reflectometer (OCDR) is too small to perform long-distance optical fiber measurement, and the light source High expectations

[0006] (2) The high-precision optical fiber length measurement system proposed by Liang Jian et al. is to measure the round-trip time difference in the optical fiber under test by adding a Faraday rotating mirror, which reduces the measurement dynamic range of the system. In addition, the system requires an external modulator Adding a polarization controller to control the polarization state of the optical signal greatly affects the measurement repeatability and stability of the system

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