Optical Fiber Comparisom.

1)Single-Mode step-index fiber:-

Advantages include the following:-

1.Minimum dispersion -All rays propagating down the fiber take approximately the same path; thus take approximately the same length of time to travel down the cable. Consequently , a pulse of light entering the cable can be reproduced at the receiving end very accurately.

2.Because of the accuracy in reproducing transmitted pulse at the receive end , wider bandwidths and higher information transmission rates are possible with single - mode step-index fibers than with the other types of fibers.

Disadvantages include the following:-

1. Because the central core is very small it is difficult to couple light into and out of this type of fiber. The source-to-fiber aperture is the smallest of all the fiber types.

2.Again, because of the small central core, a highly directive light source, such as a laser , is required to couple light into a single - mode step-index fiber.

3.Single-Mode Step index fibers are expensive and difficult to manufacture.

2)Multi mode step-index fiber:-

Advantages include the following:-

1.Multi mode step-index fibers are relatively inexpensive and simple to manufacture.

2.It is easier to couple light into and out of multimode step index fibers because they have a relatively large source to fiber aperture.

Disadvantages include the following:-

1. Light rays take many different paths down the fiber, which results in large differences in propagation times. because of this rays traveling down this type of fiber have a tendency to spread out. 

2.The bandwidths and rate of information transfer rates possible with this type of cable are less then that possible with the other types of fiber cables.

3)Multimode gradded-index fiber:-

There are no outstanding advantages or disadvantages of this type of fiber. Multi mode gradded-index fibers are easier to couple light into out of than single mode step-index fibers but are more difficult than multimode step-index fibers but less than in multimode step index fibers. This multimode gradded-index fiber is considered an intermediate fiber compared to the other fiber types.