In a fiber optic system, what is the purpose of 'index matching gel'?

The purpose of index matching gel in a fiber optic system is to reduce reflections and loss at fiber connectors. When optical fibers are joined, there is a difference in the refractive index between the fiber core and the air gap at the connection point. This mismatch can lead to significant signal loss due to reflections, as light traveling from one medium to another can be partially reflected back instead of continuing to propagate through the fiber.

Index matching gel is designed to have a refractive index that is similar to that of the fiber materials. By applying this gel at the connection, it minimizes the air gap and creates a smoother transition for the light traveling through the fibers. This reduces the amount of reflection at the joint, thereby enhancing the overall efficiency of the optical signal transmitted through the system. As a result, the use of index matching gel contributes to better signal quality and performance in fiber optic networks.