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Numerical Aperture of Single-Mode Photonic Crystal Fibers

N. A. Mortensen·J. R. Folkenberg·P. M. W. Skovgaard·J. Broeng
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Abstract

We consider the problem of radiation into free space from the end-facet of a single-mode photonic crystal fiber (PCF). We calculate the numerical aperture NA=sin theta from the half-divergence angle theta ~ tan^{-1}(lambda/pi w) with pi w^2 being the effective area of the mode in the PCF. For the fiber first presented by Knight et al. we find a numerical aperture NA ~ 0.07 which compares to standard fiber technology. We also study the effect of different hole sizes and demonstrate that the PCF technology provides a large freedom for NA-engineering. Comparing to experiments we find good agreement.

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N. A. Mortensen, J. R. Folkenberg, P. M. W. Skovgaard, J. Broeng. 2002-08-06. Numerical Aperture of Single-Mode Photonic Crystal Fibers. https://doi.org/10.1109/lpt.2002.1021980

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