Principle of Fiber Optic Communication

Author: Chief Editor: ZHANG Jinju
Publisher:
Publishing Date: 2002-01-01
Features: Excerpt: Section 2 Basic Equations of Electromagnetic Fields Since light is an electromagnetic wave, it must obey the basic laws of electromagnetic fields. The fundamental laws governing all macroscopic electromagnetic phenomena are Maxwell's equations. Therefore, the propagation of light in optical fibers must comply with Maxwell's equations, which are the basic equations of electromagnetic fields. Thus, when using wave theory methods to study the propagation of light in optical fibers, it is obviously necessary to start from Maxwell's equations. This is also the reason why, in some books on "fiber-optic communication," the analysis of optical fibers includes electromagnetic field parameters such as electric field strength E and magnetic induction strength B.
From the perspective of physical electromagnetism, the integral form of Maxwell's equations (i.e., the laws that must be satisfied within a certain range) consists of several equations, each with a specific physical meaning:
- Equations (0-1) and (0-5) represent that a time-varying electric field generates a changing magnetic field, known as the Ampère-Maxwell law (or the full-current law).
- Equations (0-2) and (0-6) represent that a changing magnetic field induces a changing electric field, known as Faraday's law of electromagnetic induction.
- Equations (0-3) and (0-7) represent that magnetic field lines are closed and have no beginning or end, known as the law of magnetic flux continuity.
- Equations (0-4) and (0-8) represent the relationship between the electric displacement vector and the source, known as Gauss's law.
Postscript: Postscript of the Self-Study Examination Syllabus
This syllabus was formulated in accordance with the "Examination Plan for the Computer Communication Engineering Program (Independent Bachelor's Degree Section) of Higher Education Self-Study Examination" developed by the Electronic and Electrical Engineering and Information Specialty Committee of the National Higher Education Self-Study Examination Guidance Committee, as well as the "Suggestions for Revising the Self-Study Examination Syllabus of Higher Education Self-Study Examination Courses" issued by the Committee.
After the preliminary draft of this syllabus was completed, experts were invited for review, and a review meeting was organized by the Electronic and Electrical Engineering and Information Specialty Committee in Beijing to discuss and evaluate it. Revisions were made based on the feedback from the review meeting. This syllabus was compiled and revised by Associate Professor ZHANG Jinju (Beijing Postal and Telecommunications Correspondence College) and others. Professors SONG Wentao (Shanghai Jiao Tong University, chief reviewer), LI Ling (Beijing University of Posts and Telecommunications, participating reviewer), and LI Wenhai (Beijing Postal and Telecommunications Correspondence College, participating reviewer) participated in the review and provided revision suggestions. Gratitude is expressed to the professors who contributed to the compilation and review of this syllabus.
National Higher Education Self-Study Examination Guidance Committee
Electronic and Electrical Engineering and Information Specialty Committee
February 1999