# Why are bend losses higher at higher wavelengths in fiber optic cables

I have been reading about fiber optic cables for the past few months, specifically about bend losses. It is often mentioned that bend losses are higher at longer wavelength light and indeed this is the case, but I am curious as to why this is so. In my research, I have not been able to find any physical explanation for this phenomenon.

If anyone knows the answer it would be of great help.

Consider how the radius of curvature (R) would appear to change as the wavelength increases. To do this we can normalize (R) to the resolving ability of the light, the wavelength ($$\lambda$$). Looking at $$R/\lambda$$ it is apparent that this normalized version of the radius of curvature becomes smaller at larger wavelengths.