June 28, 1998
June 28, 1998
July 1, 1998
3.492.1 - 3.492.14
Simulation and Animation in Optical Fiber Communication
Brian Jenkins United States Naval Academy
Students find certain concepts in fiber optic communication theory difficult to grasp. A classic example is electromagnetic mode theory in cylindrical coordinates. The solutions of the differential equation which describe the modes of the fiber are Bessel functions, with which most students are unfamiliar, and the vectorial nature of the analysis only complicates the situation. A second difficult concept is dispersion. The fact that different frequencies of light travel at different speeds in the fiber is not confusing. It is in the implications where the difficulty arises. Specifically, the concept of group velocity is physically counterintuitive, and an analysis of the pulse spreading that results because of dispersion often includes a rigorous Fourier analysis. This paper describes how computer simulation and animation can provide a visual means of simplifying these concepts so that they are easier to understand.
Computer animation has become popular in academia because the common student is visually oriented. Furthermore, some concepts are simply easier to understand visually. Modern computing tools provide the visual means to educate students more efficiently in concepts that are traditionally difficult to teach at a blackboard using mathematical derivation. In engineering, ideas also may be simple mathematically but physically counterintuitive. Computer simulation can enable a student to jump over the hurdle that an abstract physical concept presents. High levels of abstraction are especially prevalent in electromagnetic field theory and Fourier analysis, two disciplines which are fundamental in fiber optic communication theory. We use animation and simulation in MATLAB to help students grasp some of the more complex topics in these disciplines.
MATLAB is a matrix driven language which integrates numerics and graphics in a single package.1 It provides a computing environment which is relatively easy for the students to understand. This can be true even for students that have not been formally educated in higher-level programming languages. MATLAB programs are written using mathematical expressions similar to those that most engineering students are familiar with. Furthermore, it provides a comprehensive graphical environment, which includes color, surface plots in three-dimensions, etc., that enables an engineering educator to create relevant animations that provide the student with greater insight into the underlying physical processes.
Three MATLAB animations have been used in the fiber optic communications course at the Naval Academy, a senior elective in the electrical engineering department. In the first of these, the temporal and spatial behavior of various electromagnetic modes of the fiber may be observed. The second simulation illustrates why the group velocity of a pulse differs from the phase velocity of the
Jenkins, B. (1998, June), Simulation And Animation In Optical Fiber Communication Paper presented at 1998 Annual Conference, Seattle, Washington. https://peer.asee.org/7404
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