Device for reducing influence of birefringent chromatic dispersion on polarization coupling measurement of polarization maintaining optical fiber

Abstract

The invention provides a device for reducing an influence of birefringent chromatic dispersion on polarization coupling measurement of a polarization maintaining optical fiber. The device comprises a broadband light source (1), the polarization maintaining optical fiber to be measured (3), a polarization coupling detection device (4), a first connection optical fiber (53), a second connection optical fiber (54), a three-port optical circulator (2), a semi-reflective and semi-transparent light beam polarization light rotator (6), a light rotator (7), a first rotary connector (51) and a second rotary connector (52), wherein the semi-reflective and semi-transparent light beam polarization light rotator divides broadband light into two uniform light beams which simultaneously pass through theoptical fiber to be measured from the clockwise direction and the anticlockwise direction; and by using the same polarization coupling detection device, two pieces of polarization coupling measurement data of which the scanning positions are symmetric with each other are acquired at the same time. The device has extremely important practical value for parameter measurement and performance evaluation of an optic fiber gyroscope sensitive ring and can be widely applied to distributed polarization optical fiber sensing systems.

Description

Technical field [0001] The invention relates to a fiber polarization coupling measurement device, in particular to a device that reduces the influence of birefringence dispersion on the polarization coupling measurement of a polarization maintaining fiber. Background technique [0002] Polarization maintaining fiber is a special function of fiber waveguide, which refers to the fiber that can always maintain the original polarization state during transmission in the fiber when a polarization mode is excited. In the interferometric optical fiber sensing technology, the use of polarization-maintaining fiber can overcome the influence of the external environment on the polarization state of the light wave transmitted in the fiber, and suppress the polarization fading phenomenon caused by interferometric measurement. Especially in some high-precision fiber optic sensors, such as fiber optic gyroscopes, fiber optic hydrophones and so on. [0003] The main parameters for evaluating the p...

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Problems solved by technology

Research shows: (Tianhua Xu, Wencai Jing, Hongxia Zhang, et.al.Influence of birefringence dispersion on a distributed stress sensor using birefringent optical fiber, Optical Fiber Technology, Volume 15, Issue1, January 2009, Pages 83-89, and Feng Tang, Xiang-zhao Wang, Yimo Zhang, Wencai Jing, Influence of birefringence dispersion on distributed measurement of polarization coupling in birefringent fibers, Opt.Eng., Vol.46, 075006(2007)) The dual effect of network broadening and interference peak reduction reduces the spatial resolution of polarization mode coupling and reduces the detection sensitivity of coupling strength

And the influence of birefringence dispersion is dynamic, and it is related to the distance from the coupling point to the starting point of the fiber. As the distance increases, the spatial resolution of the coupling point test and the detection sensitivity of the coupling strength decrease.

With a length of 1000 meters and a birefringence of 6×10 -4 For example, take a polarization-maintaining fiber with a dispersion coefficient of 0.01ps / (km nm) as an example, and use a light source with a half-spectrum width of 50nm for interrogation. The original coherence increased from 34 μm to 0.94 mm in length, so that the spatial resolution of the polarization coupling of the polarization-maintaining fiber dropped from 5.6 cm to 1.6 meters, seriously affecting the measurement accuracy

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