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Analytic solution of cut-off wavelength of bend-insensitive fibers based on frustrated total reflection.

An analytic method for solving the cut-off wavelength of single groove-assisted bend-insensitive fiber (BIF) was proposed. Combined with the concepts of frustrated total reflection and numerical aperture, the cut-off wavelength formula for the BIF was deduced. Experimental results showed that, compared to the traditional analytic and numeric methods, this method had higher accuracy in the calculation of cut-off wavelength for BIFs that had a large proportion of depressed inner-cladding layer, which significantly expanded the range of accurately predicting the cut-off wavelength.