Channel-dropping filter based on a grating-frustrated two-core fiber

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.