Why we do not need a core diameter in calculating coupling efficiencies for a single mode fiber?

  • 18 September 2023
  • 2 replies

  • Monochrome
  • 3 replies

Hi all,

In oder to calculate coupling efficiencies for a single mode fiber (Anlysis>Fiber Coupling>Single Mode Coupling) in the sequential mode, required specifications for fibers are numerical apertures and relative positions/angles to light sources. To my knowledge, a calculation of the fiber coupling requires a core radius and/or mode field diameter (MFD) as well as numerical apertures. I was wondering if we could get the coupling efficiency even without knowing the core radius or MFD values of single mode fibers in OpticStudio. Please correct me if I’m wrong.

Your help would be highly appreciated.



Best answer by Jeff.Wilde 19 September 2023, 04:28

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For a Gaussian mode, the MFD can be found from the NA and vice versa.  So knowing the NA of a SMF is sufficient to define the fiber mode.

See, for example, Beam divergence



Hi Jeff, 

Thank you for your reply. It was a great help for me!