Analysis For The Transmission-characteristics Of Bending Fiber In Scintillantor Optic Fiber Detector

Loss and dispersion are two important aspects in fiber transfers characteristic. Its analysis has important value in application and theoretical significance. The characteristics both of loss and dispersion in the scintillantor fiber detector with a special structure bending fiber are analyzed in this paper. Firstly, a traditional bending-loss model is improved, especially for the refractive index change of bending fiber which is due to the internal stress. The correctness of this improvement is verified by calculating the loss coefficient of LP₀₁ mode. The variation of bending-loss with bending radius about two kinds of typical index profile optical fibers was analyzed by using improved theoretical model. It shows that the calculated values of improved theoretical model coincide with the reference values of better, especially at smaller bend radius. Secondly, the bending-loss of dispersion compensating fiber is analyzed by using the method of stepped approximation and transfers matrix, and the correctness of the conclusion is verified. Then, the bending-loss coefficient of different parameter fiber is calculated, and it gets the variation with the bending radius under the different structure parameters and different refractive indexes. The results indicate that the effect of cladding radius is smaller than core radius, and the refractive index has the most important effect on the bending-loss. Thirdly, a model is presented in this paper of the macro-bending loss of arbitrary-bending mono-mode fiber, which can be used not only for the arbitrary-bending mono-mode fiber but also the uniform pure bending mono-mode fiber. And the variation of bending-loss with the elliptical structure and transfers wavelength is obtained by calculating the elliptic shape fiber. Finally, a dispersion analytic formula of the bending standard mono-mode fiber is obtained. The variation of material dispersion and waveguide dispersion with wavelength and bend radius is got by numerical calculation. It shows that the material dispersion and the waveguide dispersion all increase with the increase of wavelength and bend radius, and the waveguide dispersion has oscillation characteristic.All the research results above about bending-loss and dispersion have good theoretical guidance significance in practical application of communication transmission, and have important theoretical reference value in designing of optical instrument.