Linear transformation of the polarization modes in coiled optical spun fibers II. Resonant transformation

The resonance linear transformation of the integral mutually orthogonal polarization modes has been calculated for the typical parameters of coiled optical spun fibers for four cases. In the first three cases, the spatial periods (lengths) of the polarization beats of the unperturbed linear birefringence caused by the winding of the spun fiber to the coil, unperturbed linear birefringence and circular birefringence associated with the twisting of the spun fiber pairwise coincide. It is shown that, in all three cases, pronounced resonant phenomena occur, which consist in periodic changes in the ellipticity of the intrinsic polarization modes of spun fibers. In this case, the polarization of integral eigenmodes changes from linear to right-circular, then to linear, then to left-circular, then again to linear. In all three cases, there are some qualitative differences. It is shown that, at certain values of the length, the spun fiber loses strong birefringence. The case is also considered when all three indicated lengths of polarization beats are equal to each other. It is shown that in this case the evolution of the integral polarization modes differs markedly from the three previous cases. The evolution of the state of the radiation polarization on the length of spun fibers with its representation on the Poincare sphere is calculated. An optomechanical analogy of the resonant linear transformation of orthogonal polarization modes in spun fibers is presented.