This document discusses optical waveguides and optical fibers. It covers their classification by geometry and mode structure, as well as by refractive index distribution. It also discusses how purification of materials has allowed optical fiber losses to decrease from over 1000 dB/km initially to below 0.2 dB/km currently. Total internal reflection is described as the mechanism that allows light propagation in optical fibers. Acceptance angle and numerical aperture are also defined as they relate to light entering and propagating within an optical fiber.

1. SYED AHSAN RAZA

2. Overview of Contents
 Introduction
 Ray Theory Transmission
 Electromagnetic Mode Theory for Optical Propagation
 Cylindrical Fiber
 Single Mode Fibers

3. Introduction-Optical Waveguides
 Physical structure that guides electromagnetic waves in
optical spectrum
 Optical Fibers
 Rectangular Waveguides

4. Introduction-Classification of Optical
Waveguides
 Classification by Geometry
 Planar
 Strip
 Classification by Mode Structure
 Single Mode
 Multi Mode
 Classification by Refractive Index Distribution
 Step Index
 Gradient Index

5. Purification of Materials in Optical
Fiber
 Proposals by Kao and Hockham in 1966 to utilize Optical Fiber as
communication medium (Loss>1000 dB/km)
 Conventional glass refining techniques used to bring optical fibers losses down to
4.2 dB/km
 Further research in glass refining processes allowed fiber manufacturing with
losses below 1dB/km(Operation in 0.8-0.9 μm)
 Reduced signal dispersion and lower losses found in operation at longer
wavelengths (1.1-1.6 μm)
 At 1.55 μm high performance fibers exhibited losses to the tune of 0.2 dB/km

6. Total Internal Reflection

7. Total Internal Reflection

8. Snell’s Law of Refraction

9. Transmission of light in Optical Fiber

10. Acceptance Angle
 Maximum angle to the axis at which light may enter the
fiber in order to be propagated
 For a fiber with regular cross section, an incident
meridional ray greater than the critical angle will continue
to be reflected and transmitted inside the fiber

11. Acceptance Angle

12. Numerical Aperture
 Provides the relationship between
 Core
 Cladding
 Air

13. Numerical Aperture

14. Numerical Aperture

15. Numerical Aperture