Fiber optic interferometric system for reducing influence of fiber birefringence

Abstract

The invention relates to a fiber optic interferometric system for reducing the influence of fiber birefringence. Laser is emitted by a laser device and transmitted to a fiber optic coupler through a source fiber; the laser is split by the coupler and then output to a metric arm and a reference arm of the fiber optic interferometric system respectively, wherein, one path of light is incident to light reflection device of the metric arm through a fiber optic depolarizer of the metric arm and an optical fiber of the metric arm; the reflected light returns to the fiber optic coupler through the original path; the other path of light is incident to a light reflection device of the reference arm through a fiber optic depolarizer of the reference arm and an optical fiber of the reference arm; the reflected light returns to the fiber optic coupler through the original path; the two path of reflected light form an interference light signal in the coupler; the signal is received by a photoelectric detector as an interference signal through an optical fiber of the detector; and the interference signal is transmitted to an operational processing system through a signal transmission line to obtain the size of the outside physical quantity signal. The fiber optic interferometric system used for metering outside physical quantities such as vibration eliminates the influence of the random variation of the polarization state in the ordinary fiber optic interferometric system on the signal of the fiber optic interferometric system.

Description

technical field [0001] The invention relates to an optical fiber interferometric measurement system, in particular to an optical fiber interferometric measurement system with the function of measuring external physical quantities based on a Michelson optical fiber interferometric device. Background technique [0002] The optical fiber interferometry system uses all-fiber devices, which has the characteristics of strong anti-electromagnetic interference, high detection sensitivity, and passive sensor operation. It is widely used in the measurement of physical quantities such as vibration, temperature, and displacement. [0003] According to the light interference theory, only light with the same polarization state can form interference. When there is birefringence in the fiber, the propagation speed of light in different polarization states is different, and the resulting interference signal will also change accordingly. Therefore, when there is birefringence in the fiber, in...

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Problems solved by technology

[0025] From the above review of the Michelson fiber optic interferometry device based on the non-ideal Faraday rotating mirror, it can be seen that due to the error in the polarization rotation angle of the Faraday rotating mirror itself, the polarization selection angle will be affected by the central wavelength of the light source, the ambient temperature and the magnetic field. Changes due to changes, making it impossible to maintain a complete 90° polarization rotation, and unable to effectively suppress the polarization noise caused by the birefringence of the single-mode fiber, thus greatly reducing the stability and practicability of the fiber-optic interferometry system

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