Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 12

The end faces of two optical fibers with core refractive indices of 1.485 are perfectly aligned and have a small gap between them. If this gap is filled with a gel that has a refractive index of 1.305, find the optical power in decibels reflected at one interface of this joint. If the gap is very small, what is the power loss in decibels through the joint when no index-matching material is used Note that n = 1.0 for air.