We present experimental results on the operation of a dissimilar two-core fiber segment as a channel-dropping filter based on the principle of grating-frustrated coupling. The restoration of 100% coupling by ultraviolet (UV)-tuning of the fiber is demonstrated over a bandwidth in excess of 20 nm. It is also shown that a grating can be inscribed in one of the cores while maintaining perfect coupling conditions between the cores.
A.-C. Jacob-Poulin, R. e, S. LaRochelle, D. Faucher, and G. R. Atkins, "Channel-Dropping Filter Based on a Grating-Frustrated Two-Core Fiber," J. Lightwave Technol. 18, 715- (2000)