Research On Optical Coherent Polarization Detection Method For The Polarization Maintaining Fiber Performance Detection

Optical low coherent polarization detection(OCDP) technology is valuable to optic fibergyroscope. Fiber-optic gyroscopehas broad development in aviation, space, sailing, weapons,geology, oil exploration and so on. So if we want to improve the performance of optic fibergyroscope, we must know how to appraise the component in it. This paper studies the optical lowcoherent polarization detection instrument can test the place of polarization coupling point andstrength of coupling of fiber optic ring, and also test the extinction ratio of Y waveguide andpolarization-maintaining fiber coupler. Based on the White light interference principle, we designa OCDP. In this paper, we use Jones matrix to set up model. At last we use the OCDP test thepolarization of fiber optical ring, Y waveguide and polarization-maintaining fiber coupler. Theexperiment results show this system is effective. Specific content is:1In this paper, the method of detecting the polarization coupling on the white lightinterference use the Michelson interferometer to compensate the optical path difference which isproduced by the coupling point. The interference signal is analyzed to obtain the couplingposition and strength of the coupling. Based on Jones matrix of white light interference light pathset up the mathematical model.2Constructing solution and experimental plan platform of OCDP. And set up theexperimental platform to detect the performance of the key parts, discriminate the differencebetween different couplers, which is beneficial to choice the device. Contrast the characteristicsof different light source, choose SLD wide spectrum light source in the system. And then we testthe whole light path of the OCDP, the dynamic range of interference signal is84dB, polarizationsensitivity is-84dB, the resolution is the less than5cm.3In the OCDP system we designed a alignment method to connet two PMF together. Weadd a light intensity detector and two alignment devices in the OCDP. The experimental resultsshow that the above method can effectively achieve the polarization-maintaining fiber alignment,ratio of axial is1°, measure the polarization coupling of optical fiber ring without optical fiberfusion splicing, and does not destroy the symmetry of sensitive ring. Overall, the method issimple and high precision. 4After testing the coupling performance of fiber optic ring, can also be used to test otherdevices, based on the Jones matrix, we analysis the light of testing Y waveguide and PMF couplerrespectively,and the extinction ratio is22.6dB. A second coherent peak appears in the interferencesingle, we use the relation of light spectral characteristics and coherent function. Spectrumfunction Inverse Fourier Transform, and then look for of the influence of spectrum to coherentfunction. The performance of the light source is evaluated by the testing data.