# Attenuation losses in Optical Fibers

An optical fiber is made of either glass or plastic material. The refractive index of the material plays an important role in the transmission of an optical signal used further in communications. This signal travel inside the core of an optical fiber with the speed of light. As you know the total internal reflection (TIR) is the principle on which the light signal propagates in the core which takes to multiple reflections at the core-cladding interface. For long distances, the optical fibers are grounded under the surface of the earth. So it is obvious the optical fiber will be bend at corner places which may arise the possibility of signal loss in optical fiber.

Here some hints through the questions you may take also understanding the working and reason of signal losses.

1Q. What is the critical angle?

2Q. What is an optical fiber?

3Q. On the basis of the refractive index, how many types of optical fiber are?

4Q. What is guided modes in optical fiber?

5Q. How many modes are possible in step index optical fiber?

6Q. How many modes are possible in Graded-Index Optical Fiber?

7Q. Is refractive index maximum or minimum at the central axis of the graded index optical fiber core?

8Q. What do you mean by acceptance angle and cone for an optical fiber?

9Q. Numerical  Aperture (NA) is dimensionless, what information you get from it?

http://www.apniphysics.com/viva-questions-stewart-gees-method-experiment/

10Q. If there are two optical fibers one have NA=0.23 and second have NA=0.52 which have more capacity to carry a large number of optical signals?

11Q. In step index optical fiber two extreme modes are available one is with the extreme ray that makes the maximum angle (equal to the acceptance angle) and second correspond to the central axis. Does both the light rays reach at the receiving end at the same time or not?

12Q. What do you understand by the bandwidth and normalized frequency of an optical fiber?

13Q. Can you explain the dispersion in the prism and how it is different in optical fibers?

14Q. What are the two transmission characteristics in optical fibers?

15Q. In which unit you observe the signal loss?

16Q. What is the formula for attenuation loss?

17Q. What are the main applications of the optical fibers?

NOTE: use it for http://www.samm.com/calculating-fiber-loss-and-maximum-distance-estimates

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