Investigations of bending loss oscillations in large mode area photonic crystal fibers

We demonstrate that bending loss in large mode area photonic crystal fiber (LMA PCF) reveals a strong dependence of the amplitude and location of the loss peaks on the bend radius and on the fiber angular orientation. To do so we measured bending induced loss in LMA PCF as a function of wavelength in a broad spectral range (800-1500 nm) for different bend radii and for different angular orientations of the fiber with respect to the bending plane. The oscillations of bending loss with the bend radius and orientation are particularly well pronounced when the radiative component of the fundamental mode is reflected from the flat boundary of the holey cladding. We also show the good agreement between our measurement results and earlier simulations relying on a finite element method with perfectly matched layers and equivalent index model.