Measuring device and method for length difference between arms of optical fiber interferometer

Abstract

The invention provides a measuring device and method for the length difference between arms of an optical fiber interferometer. The measuring device comprises a laser source module, a measured optical fiber interferometer module, a reference interferometer module and an acquisition and control module, wherein laser with wavelength varying linearly is emitted by a tunable laser to enter the measured optical fiber interferometer module and the reference interferometer module, a computer controls an analog quantity output board card to drive piezoelectric ceramic with optical fibers wound thereon, and accurate phase variation of the two modules is acquired after acquired signal demodulation; the optical path difference between two arms of the reference interferometer is changed, and meanwhile, the optical path difference variation is demodulated by the aid of a distributed feedback laser in the source module in combination with a PGC algorithm; the first step is repeated after the optical path difference between the two arms of the reference interferometer is changed; the length difference between arms of the measured optical fiber interferometer is calculated according to a measuring formula for the length difference between the arms. The piezoelectric ceramic, the distributed feedback laser and the like are introduced, the length difference between the arms of the measured optical fiber interferometer can be measured accurately with the PGC algorithm, and the measuring device has the advantages of high measurement accuracy, wide range, capability of automatic calibration and the like.

Description

technical field [0001] The invention relates to a device for measuring the performance of an optical fiber sensor, and the invention also relates to a method for measuring the performance of the optical fiber sensor. Specifically, it is a measuring device and a measuring method for the arm length difference of an optical fiber interferometer. Background technique [0002] With the development of optical communication technology, fiber optic sensing technology has also developed rapidly due to its advantages of no electromagnetic interference, compact structure and high sensitivity. Mach-Zehnder type interferometer (such as Figure 4 ) and Machelson-type interferometers (such as Figure 5 ) as the main sensing element can be directly used to detect physical quantities such as underwater sound, current, magnetic field, and temperature. The current fiber optic interferometer can be divided into balanced type and unbalanced type according to whether the arm length difference b...

AI Technical Summary

Problems solved by technology

In 2007, Yang Jun of Harbin Engineering University and others published the article "Accurate Measurement of Arm Length Difference of Optical Fiber Mach-Zehnder Interferometer" in Journal of Harbin Engineering University. 28 (8): 740-742. Measurement accuracy, but the measurement length of this method is mainly limited by the scanning range of the scanning table, so the measurable arm length difference is relatively short

Since voltage needs to be applied to the two arms of the fiber optic interferometer, this method has the risk of destroying the sensor, and cannot be applied to the arm length difference measurement of sensing devices such as hydrophones that have been packaged.

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