Contributors: Mai Vinh Nguen

Table of Contents

Background

Topic of fiber optics is divided into small sub-topic. Our group chooses to work on dispersion.

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• What is dispersion?
• How many types of dispersion in optical fibers?
• In which situation certain type of dispersion dominates others?

Our explanation (original hypothesis)

Dispersion based on our own knowledge is a phenomenon relating to light traveling from one medium to another and light with different wavelength will bend at different angels and produce dispersion. One typical example will be a white light passing through a transparent prism will divided in to a spectrum of light with blue light bend at highest angle and red light at lowest angle. Hence, blue light is in the bottom and red light is at the top of the spectrum

Critical evaluation

Our explanation is only based on our secondary knowledge regarding light dispersion. More studies need to be done to understand dispersion in details and how it relates to fiber optics.

Results

Dispersion is defined as the spreading of light pulse when they travel a fiber. This phenomenon is due to the fact that speed of light depends on its wavelength and propagation mode. In case of travelling long distances, slight differences in speed accumulate. As a result, bit errors will occur.

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In the above formula, dispersion is in the unit of time per unit distance (normally nanosecond or picosecond per kilometer) and pulse spreading is in the unit of time (usually nanosecond or picosecond).

Conclusions

Our initial theory regarding dispersion in fiber optics is only about chromatic dispersion. By doing research and further study, dispersions are understood in more details which include four major type of dispersion in optical fibers. In what situation each type of dispersions dominate are also well understood.

Studied material

Hecht, J. (2011). Understanding fiber optics (5th ed.). Pearson Prentice Hall

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