Fiber optic and light propagation


Published on

Published in: Education, Business, Technology
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Fiber optic and light propagation

  1. 1. ECC3601: OPTICAL COMMUNICATION Lecture 3: Introduction to Fiber Optic and Light Propagation Makhfudzah bt. Mokhtar, PhD. Department of Computer and Communication Systems Faculty of Engineering University Putra Malaysia
  2. 2. LEARNING OUTCOMES At the end of this lecture, students should be able to: -Describe ‘optical waveguide’ -Explain basic characteristics of fiber optic.
  3. 3. What is Optical Waveguide? An optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum. Common types of optical waveguides include optical fiber and rectangular waveguides. Optical waveguides are used as components in integrated optical circuits or as the transmission medium in local and long haul optical communication systems. Optical waveguides can be classified according to their geometry (planar, strip, or fiber waveguides), mode structure (singlemode, multi-mode), refractive index distribution (step or gradient index) and material (glass, polymer, semiconductor). Optical waveguide From Wikipedia, the free encyclopedia
  4. 4. Optical waveguide: geometry Conceptual diagram of light propagating from an optical fiber waveguide to a rectangular optical waveguide Optical waveguide
  5. 5. Optical waveguide: geometry Light can be guided by planar or rectangular wave guides, or by optical fibers. Optical waveguide
  6. 6. Optical fiber: structure Chapter 24: Fiber Optics Copyright © Delmar Thomson Learning
  7. 7. Optical fiber: structure Fiber Optic Core: The inner light-carrying layer with a high index of refraction. Cladding: The middle layer, which serves to confine the light to the core. It has a lower refraction index than the core. Jacket: The outer layer, which serves as a "shock absorber" to protect the core and cladding from damage. The coating usually comprises one or more coats of a plastic material to protect the fiber from the physical environment. Sometimes metallic sheaths are added to the coating for further physical protection. Optical waveguide
  8. 8. How does light propagate along the fiber? See video ‘Fiber optic cables-how they work’
  9. 9. Light refraction Optical Image: Physics behind the Scenes
  10. 10. Light refraction and reflection * Refraction is the change in direction of a wave due to a change in its medium. * Total internal reflection is a phenomenon that happens when a propagating wave strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. Optical waveguide From Wikipedia, the free encyclopedia
  11. 11. Light refraction and reflection Optical Communication: Slide Prof. Dr. Mohd. Adzir Mahdi
  12. 12. Optical fiber: modes Based on modes, fiber can be divided into : i) SINGLE MODE FIBER (SMF) and ii) MULTI MODE FIBER (MMF) * Single mode fiber is an optical fiber that carries only a single ray of light (mode). * Multi mode fiber is an optical fiber that carries multiple light rays or modes concurrently, each at a slightly different reflection angle within the optical fiber core. Multimode fiber transmission is used for relatively short distances because the modes tend to disperse over longer lengths (this is called modal dispersion) . For longer distances, single mode fiber (sometimes called monomode) fiber is used. Multimode fiber has a larger core than single mode. Single mode fiber | multi mode fiber Wikipedia |
  13. 13. Optical fiber: modes How dispersion exist in multi-mode fiber Multimode step-index fibers trap light with many different entrance angles. •Each mode in a step-index multimode fiber is associated with a different entrance angle. •Each mode therefore travels along a different path through the fiber. Different propagating modes have different velocities. •As an optical pulse travels down a multimode fiber, the pulse begins to spread. Pulses that enter well separated from each other will eventually overlap each other. This limits the distance over which the fiber can transport data. Multimode stepindex fibers are not well suited for data transport and communications. Optical waveguide
  14. 14. Optical fiber: modes Light emerging from a multi-mode fiber Light emerging from a single-mode fiber Optical waveguide
  15. 15. Optical fiber: gradient • Both types of fiber described earlier are known as step-index fibers because the index of refraction changes radically between the core and the cladding • Graded-index fiber is a compromise multimode fiber, but the index of refraction gradually decreases away from the center of the core • Graded-index fiber has less dispersion than a multimode step-index fiber Step-index fiber Graded-index fiber Chapter 24: Fiber Optics Copyright © Delmar Thomson Learning
  16. 16. Preparation for Quiz 1 -Revise Lecture 2 slide