Accurate Empirical Relations for Characterising a Single-mode Matched Clad Fiber from its Far-field Pattern

Abstract

We provide accurate empirical relations for characterising a single-mode matched clad fiber from its far-field radiation pattern. The empirical relations can be used to calculate accurately the Petermann 2, the rms and d x mode field diameters of the fiber. For a measurement error of < 2' in the far-field angles 0 h , Θ 40 or θ χ , where 0 h is the half intensity angle and Θ 40 (θ χ ) corresponds to the -40 dB (-oo dB) intensity level, the empirical relations are found to give an error of <!.!% in Petermann 2 MFD of 10 urn (at λ = 1.3μπι) in the range 2.0<V<2.4. The empirical relations can also be used to obtain the ESI parameters of a graded-index single-mode fiber.