Relation between MFD and Core radius of a Single Mode Fiber

Hi I am trying to simulate a single mode fiber for edge coupler. In the application library, I saw that for the edge coupler SMF-28 has been used and the MODE Field diameter was calculated to be found as 10.4 µm.

I am trying to simulate an SMF-400 fiber. For that, I am using a core radius of 1.3 µm. My question is there any direct relation between Mode Field Diameter and Core radius of an optical Fiber?
Thanks.

Hi @arefin.2,

Yes, in general if you increase the core radius of a fiber the mode diameter will increase as well. I believe that there is an analytic approximation for step index fibers, you should consult a fiber optics textbook to be sure.

Best Regards,
Kyle

Hello @arefin.2,

The MFD depends on the index contrast between the core and cladding. Usually fiber optic datasheets provide the core diameter as well. If you look at this post below I describe a method of determining this index contrast, or at least of replicating your fiber mode. Please take a look.

Fiber optic components; developing models from a datasheet

Cheers,

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