Integrated common-path interference electric field measurement system for eliminating polarization dependent noise

Abstract

The invention discloses an integrated common-path interference electric field measurement system for eliminating polarization dependent noise, and belongs to the technical field of the integrated common-path interference electric field measurement system. The system comprises a light source, and a polarizer, an input polarization maintaining optical fiber, an electro-optical crystal, an output polarization maintaining optical fiber and a polarization analyzer which are arranged on the coaxial light path of the output beams of the light source in turn. The light source is a broadband light source. The length L of the input polarization maintaining optical fiber and the output polarization maintaining optical fiber meets: the value obtained in a way that L is multiplied by the central wavelength of the broadband light source and then divided by the beat length of the polarization maintaining optical fibers is greater than or equal to the coherent length of the broadband light source. According to the measurement system, the broadband light source is used and the input and output polarization maintaining optical fibers of the set length are used so that the polarization dependent noise can be effectively eliminated, the polarization dependent noise produced in the integrated common-path interference electric field measurement system can be greatly reduced and the measurement accuracy and precision of the integrated common-path interference electric field measurement system can be enhanced.

Description

technical field [0001] The invention belongs to the technical field of an integrated common-path interference electric field measurement system, in particular to an integrated common-path interference electric field measurement system for eliminating polarization-related noise. Background technique [0002] At present, in the electric field measurement system based on the integrated common path interferometric sensor, such as figure 1 As shown, the light wave generated by the light source is polarized by the polarizer P and then converted into linearly polarized light, and the linearly polarized light enters the electro-optic crystal LN (such as LiNbO 3 crystal), the elliptically polarized light emitted from the crystal enters the polarizer A through the output polarization-maintaining fiber PMF, so far the phase modulation of the light wave is transformed into the light intensity modulation (that is, the phase that cannot be directly measured is transformed into a directly ...

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Problems solved by technology

for figure 1 The optical path shown involves a total of four alignment angles (α 1 、α 2 、α 3 and alpha 4 ), if the Jones matrix method is used for analysis, it will be very complicated

[0004] Moreover, the beat length of the currently used polarization-maintaining fiber PMF is about 4mm, and its birefringence effect is very significant. A slight vibration or temperature change in the environment can make the phase difference φ caused by the input polarization-maintaining fiber fi and the phase difference φ caused by the output polarization maintaining fiber fo Produces violent fluctuations that cause severe polarization-dependent noise in the measurement system

[0005] At present, lasers are usually used as light sources in optical sensing applications, and the spectral linewidth of lasers is 10 -6 nm level, the corresponding coherence length is hundreds of kilometers (Zhang Sanhui. University Physics. Beijing: Tsinghua University Press, 2000:129-133.), so it is difficult to eliminate polarization-related noise by increasing the length of the optical fiber when using a laser light source

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