| In recent years, chiral fiber and devices have attracted a great deal of researcher interest. The research shows that the light in fiber filled with chiral media will decompose left- and right-handed circularly polarized (LCP and RCP) modes with different propagation coefficients. For this reason, the chiral fiber possesses a lot of characteristics which are different from that of the ordinary fiber, based on which a number of novel devices, including polarization switches, polarization converter, sensors, and so on can be developed. In this thesis, the coupling of chiral fibers is studied and the optical characteristics of some novel derived chiral devices are discussed.In this thesis, firstly, from Maxwell equations and by using constitutive relations of the chiral medium,the Helmholtz's equations for chiral fiber is derived. The expressions for the transverse distributions of two circularly polarized modes are given. In the approximation of weak coupling, based on coupled-mode theory, the coupled equations of two chiral fibers are derived, and the expressions for calculating the coefficients are given.Secondly, the optical characteristics of a chiral coupler and a chiral resonator are analyzed numerically by using the transfer matrix method. The effect of the chiral parameters on the optical property of such devices is discussed. The potential application is pointed out.Thirdly, the coupled equations of three chiral fibers which have two types of relations (equally weighted and side-by-side distributed) are obtained with the method mentioned above. The coupled equations for the coupling between the ordinary fiber and the chiral fiber in the corresponding distribution are also given.Finally, the properties of 3×3 couplers with equally weighted and side-by-side three fibers are analyzed. For a special case, the optical property of 3×3 coupler consisted of an ordinary fiber and two chiral fibers are given. The potential applications in the optical device are pointed out. |
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