The frequency dependence of the coupling length in a twin-core photonic bandgap fiber is investigated numerically. In contrast to the case of index-guiding fibers, the coupling length exhibits a maximum if the cores are sufficiently well separated. The fiber design proposed is of interest for fabricating broadband tunable couplers.
© 2005 Optical Society of America
Fiber Optics and Optical Communications
J. Lægsgaard, "Directional coupling in twin-core photonic bandgap fibers," Opt. Lett. 30, 3281-3283 (2005)