  Leakage channel fibers, designed to suppress higher-order modes, demonstrate
resonant power loss at certain critical radii of curvature. Outside the
resonance, the power recovers to the levels offset by the usual mechanism of
bend-induced loss. Using C$^2$-imaging, we experimentally characterize this
anomaly and identify the corresponding physical mechanism as the radiative
decay of the fundamental mode mediated by the resonant coupling to a cladding
mode.
