Numerical analysis of primary rainbows from a homogeneous cylinder and an optical fiber for incident low-coherent light

This work provides a numerical study of the scattering of low-coherent light by an infinite right circular cylinder and various types of optical fiber (with step- and graded-index profiles) in the vicinity of primary rainbows, caused by light that has been subjected to one internal reflection. The scattered intensity is analyzed in terms of the Fourier transform as well as in the time domain (by examining the impulse response of a fiber) with the aim to obtain a detailed information about the scattering process. The analysis reveals a wealth of information about the scattering process that is not obvious when a fiber is illuminated by a temporally coherent light source. The results also provide an idea for the characterization of the core size of step-index optical fibers. (C) 2017 Elsevier Ltd. All rights reserved.