Using conventional coupled-mode theory, a set of coupled-mode equations are formulated for single-helix chiral fiber long-period gratings. A helical-core fiber is analyzed as an example. The analysis is simple in mathematical form and intuitive in physical concept. Based on the analysis, the polarization independence of mode coupling in special fiber gratings is revealed. The transmission characteristics of helical-core fibers are also simulated and discussed.
© 2011 Chinese Optics Letters
Li Yang, Linlin Xue, Jue Su, and Jingren Qian, "Coupled-mode analysis for single-helix chiral fiber gratings with small core-of fset," Chin. Opt. Lett. 9, 070603-070603 (2011)