Fiber mode field diameter calculation

- November 8, 2021 at 6:03 am
  
  iqnlo
  Subscriber
  
  Hi all
  May I ask how do you calculate the fibres when doing simulation?
  The parameters I have are NA and MFD (mode field diameter). Is there a good way to solve the refractive index of core and cladding? I remember there was a dissection on this topic but I could not find it now.....
- November 8, 2021 at 5:55 pm
  
  Guilin Sun
  Ansys Employee
  
  This is a very interesting, and one of the often-asked similar questions. The parameters you give are resulting parameters, not deterministic parameters. The latter determines the physical properties of the fiber, eg, geometry radii of the core and claddings; and their material refractive index. You could deduct the deterministic parameters from the resulting parameters. According to my experience for Corning SMF 28, the results are contradictory: NA is from geometric optics where there is a sharp boundary w/o optical field; however the mode profile is continuous from peak to very small values.
  PI-1424-AEN.pdf (corning.com)
  In addition, the MFD is a mathematic parameters, and different people may have different definitions.
  In some cases even the manufacturers do not provide them, due to several reasons.
  Therefore, if you want to simulate such fiber accurately, you will need to get the deterministic parameters, either accurately or approximately, from somewhere, such as the published papers.
  
  You may refer this article here Mode radius, explained by RP Photonics Encyclopedia; diameter, spot size, Gaussian beam, waveguide, single-mode fiber (rp-photonics.com) for more information about MDF.