All-fiber interference method and device for suppressing backscattering by utilizing polarization coding
A technology of backscattered light and backscattering, which is applied in the transmission of sensing components, measuring devices, instruments, etc. using optical devices, can solve the problems of limiting measurement sensitivity and reducing the signal-to-noise ratio of the system, and achieve backscattering suppression. , the effect of improving the signal-to-noise ratio
Active Publication Date: 2020-06-05
EAST CHINA NORMAL UNIV
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[0003] The present invention provides an all-fiber interference method and device using polarization encoding to suppress backscattering, aiming to solve the problems caused by the loss in the optical path and the accumulated backscattering in the sensing fiber in the existing long-distance optical fiber sensing measurement technology , leading to a decrease in the signal-to-noise ratio of the system and limiting the measurement sensitivity
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[0050] In order to illustrate the technical solutions of the present invention, specific examples are used below to illustrate.
[0051] The all-fiber interference method using polarization encoding to suppress backscattering according to the present invention comprises the following steps:
[0052] Step 1: A signal transmitting module is composed of a coherent light source to generate two beams of light waves (x-polarized light and y-polarized light) with orthogonal polarization;
[0053] Step 2: In the phase modulation module, use the x-polarized light and y-polarized light generated by the above-mentioned signal transmitting module to sense the phase caused by the external physical field. In this process, the optical paths of x-polarized light, y-polarized light, parasitic backscattered light of x-polarized light and parasitic backscattered light of y-polarized light are as follows: figure 1 shown. Wherein, x-polarized light and y-polarized light are equal optical path pr...
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The invention provides an all-fiber interference method for suppressing backscattering by utilizing polarization coding. According to the invention, a polarization coding technology is adopted to enable two beams of coherent light waves to be vertical in polarization and be propagated in an equal optical path, and enable backscattering light in an interference optical path to be propagated in an unequal optical path. In combination with a low-coherence interference technology, the purpose that backscattered light cannot be interfered while effective light interference is achieved is achieved,and the all-fiber interference method with the backscattering suppression characteristic is achieved. The device comprises a signal transmitting module, a phase modulation module and an interference measurement module. The signal transmitting module generates two beams of polarized orthogonal light waves; the phase modulation module is used for realizing equal-optical-path transmission of polarized orthogonal light waves and unequal-optical-path transmission of parasitic backscattered light; and the interference measurement module is used for realizing equal-optical-path interference. Comparedwith the traditional all-fiber interference, the method and the device provided by the invention reduce the influence of back scattering and realize high-precision interference measurement of long-distance transmission through polarization encoding and low-coherence interference technologies.
Description
technical field [0001] The invention relates to the technical field of optics and precision measurement, in particular to a brand-new all-fiber interference method and device for suppressing backscattering by using polarization coding. Background technique [0002] Distributed optical fiber sensing is widely used in perimeter early warning, oil pipeline detection and other fields due to its advantages of long life, high sensitivity, high voltage resistance, good resistance to electromagnetic interference, and simple system. However, when realizing ultra-long-distance optical fiber sensing, due to the limitation of optical path loss, the effective light decays exponentially with the increase of sensing distance. In addition, due to the non-ideality of optical fibers and devices in the optical path, part of the light interacts with free-oscillating molecules, atoms and other particles in the optical fiber, resulting in backscattered (reflected) light. The spurious light forme...
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IPC IPC(8): G01D5/353
CPCG01D5/35358
Inventor 吴媛郭进先
Owner EAST CHINA NORMAL UNIV