Graded-profile fibers multimode

Figure 7.9 Refractive index profiles of three common types of optical glass fiber multimode step index, multimode graded index, and single mode.

Graded index multimode fibers are far more complicated than their single mode counterparts. The relevant expressions are stated to permit insight into the relationships between material properties and fiber performance. The index profile as a function of radius r is given by Equation 4. For such a profile, the intermodal group delay may be approximated by... 

Y. Koike et al. [107, 108] obtained commercial high-bandwidth graded-index polymer optical fiber with quadratic RID profile and capable of transmitting optical signals at a high rate in short-wave multimedia (multimodal, multichannel) translation networks by the method of interphase gel-polymerization [109], which could not be performed using polymer optieal fibers possessing a stepwise RID profile [108]. 

---