Abstract:

Teaching electromagnetic propagation as well as signal transmission in optical fibers to undergraduate students is a challenging task. Most students do not have a sufficient background in mathematics and/or electromagnetic theory so, usually, fail to comprehend the mathematical analysis and associate it with actual waveguiding phenomena. An additional difficulty is the fact that due to the cylindrical geometry of the fiber, the student must be or get familiar with cylindrical coordinates as well as Bessel equations and functions (not a trivial topic) and, in fact, the usual complaint of the students is that they “feel lost in mathematics”. Moreover, in most cases, propagation and transmission processes within fibers are presented in the framework of “Optical Communications” course which sets strict limitations in the available teaching time. Yet, in order the students to appreciate the role (and limitations) of optical fibers as elements of optical communication links, they need to have a mathematically sound knowledge on the waveguiding process as well as the transmission degradation phenomena such as signal attenuation and signal dispersion.

Following the above rationale, the aim of the article is to present a way of introducing students to fiber waveguiding and the associated transmission phenomena by avoiding the use of complicated mathematics and by only requiring an elementary background in mathematics and electromagnetic theory. The described approach has been applied in the framework of the “Optical Communications” course at the Electrical & Electronic Engineering Educators Dept., School for Pedagogical & Technological Education (ASPETE), Athens, Greece. Graduates of ASPETE may be employed as teachers at technological high schools so comprehension of basic engineering concepts and procedures is essential for them. Thus, analysis of fiber waveguides is carried out in two phases - the first one deals with essential physical features of waveguiding (that are presented in a simplified way with a limited use of mathematics) while the second one includes the associated mathematical analysis. The benefit of this procedure is two-fold; a sufficient prior knowledge on the waveguiding processes (even by using simple mathematics) enables students to address issues and calculations related to fiber links and, at the same time, it helps them to better comprehend propagation and transmission phenomena when they are presented in a full analysis manner. The course module also addresses common students’ misconceptions regarding issues such as the optical ray approximation, the group velocity concept, the chromatic dispersion and the transmission capacity of the optical fiber as expressed by the bandwidth/distance or the bit-rate/distance product. The module is followed by a short test with questions and problems on fiber waveguiding regarding both, the basic facts and the more advanced issues.

Keywords:

Engineering Education, Electronic Engineering Education, Optical Fibers.