Multimode Fiber Materials

For telecommunication purpose optical fibers, materials used to make Multimode fiber is same as that used to make Singlemode fiber, that is Silica glass. However the design of Multimode fiber is different that allows propagation of several modes in Multimode fiber. As the names indicate, a single mode fiiber allows propagation of a single mode and a multimode fiber allows propagation of multiple modes.

Doping materials are added to the core region to make the refractive index slightly higher than that of cladding. Base outer coating materials are also exactly same as singlemode fibers, that is Ultraviolet curable acrylate. There will be two coating layers, Inner primary coating with soft acrylate and outer primary coating with hard acrylate.

Differences between singlemode and multimode optical fibers are in the geometrical dimensions of core and cladding. Core/Cladding diameter of predominantly used Multimode fiber is usually 50/125 micrometers. Other core diameters that are typically used in the industry and commercially available in the market are 62.5/125 micrometers, 100/140 micrometers, 200/240 micrometers, 200/280 micrometers, 200/300 micrometers, 200/380 micrometers, 200/230 micrometers, (465-485)/500 micrometers, (715-735)/750 micrometers and (965-985)/1000 micrometers.

Note that primary coating diameter of the above mentioned core/cladding combinations would be changed according to the cladding diameter. It does not necessarily be 250 micrometers.