Optical Fiber Principles: Waveguides, Modes, and Materials - Prof. Pathak, Summaries of Fiction Writing

Download Optical Fiber Principles: Waveguides, Modes, and Materials - Prof. Pathak and more Summaries Fiction Writing in PDF only on Docsity!

OPTICAL FIBERS:

STRUCTURES,

WAVEGUIDING,

AND

FABRICATION

The Nature of Light

1. Light is a transverse, electromagnetic wave that can be seen by humans.
2. The wave nature of light was first illustrated through experiments on diffraction and interference.
3. Like all electromagnetic waves, light can travel through a vacuum.
4. The transverse nature of light can be demonstrated through polarization.
5. The speed of light depends upon the medium through which it travels.
6. Intensity is the absolute measure of a light wave's power density
7. Brightness is the relative intensity as perceived by the average human eye.
8. The frequency of a light wave is related to its energy and color.
9. The wavelength of a light wave is inversely proportional to its frequency.

Spherical and plane wave fronts

Field distributions in plane E&M waves

Amplitude Fluctuation in an Electromagnetic Wave. Here both the electric field and the magnetic field are shown as a single field oscillating about a locus of points which forms the line of travel.

Index of Refraction

n 1 <n 2 <n 3

• When light passes from rare to dense medium, it bends towards the normal
• When light passes from dense to rare medium, it bends away from the normal
• Law of refraction is
  • The incident ray, the normal, and the refracted ray at the point of incident all lies in the same plane
  • The ratio of the sine of angle incidence to the sine of angle of refraction is always constant - This ratio is called refractive index Refraction and reflection

Diagrams illustrating reflection and refraction of light, viewed as waves and particles.

• Total internal reflection
  • When light passes from denser medium to rarer medium it bends away from the normal
  • The incident angle for which angle of refraction is 90° is called critical angle
  • If incident angle becomes more than critical angle all the light will reflect back to the same denser medium
  • Such a phenomenon is called total internal reflection Refraction and reflection

Angle of Refraction Angle of Incidence =^ Angle of Reflection D The critical angle of incidence. Glass Air B Glass Air Angle of Incidence A Glass Air Critical Angle C 900 Glass Air