lecture_6.pptx polarisation of light.

1. Polarization Of Light
Lecture # 6

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3. • Polarization is a property of waves that can oscillate with more than
one orientation.
• Electromagnetic waves such as light exhibit polarization, as do some
other types of wave, such as gravitational waves.
• Sound waves in a gas or liquid do not exhibit polarization, since the
oscillation is always in the direction the wave travels.

4. • Polarized Light:
Vibrations lie on one single plane only.
• Unpolarized Light:
Superposition of many beams, in the same direction of propagation,
but each with random polarization.
A light wave that is vibrating in more than one plane is referred to as
unpolarized light.

6. • It is possible to transform unpolarized light into polarized light.
• The process of transforming unpolarized light into polarized light is
known as polarization.
• The direction of electric field is known as polarization of the wave. For
example, consider an electric field propagating in the positive z
direction and polarized in the x direction.
• Polarization of electromagnetic wave determines the direction of
force that electromagnetic wave exerts on charged particle in the
path of wave through the application of Lorentz force law.

7. • Many optical application critically depend on the nature and
manipulation of polarization of electromagnetic wave.
• The electric field component is used to define the plane of
polarization because many common electromagnetic-wave detectors
respond to the electric forces on electrons in materials, not the
magnetic forces.

8. Linear Polarization
• In linear polarization, the fields oscillate in a single direction.
• Light may be linearly polarized along any line that is perpendicular to
the direction of propagation.
• If the oscillation does take place in only one direction then the wave is
said to be linearly polarized (or plane polarized) in that direction
• When light is linearly polarized in the vertical direction the electron
accelerates in the vertical direction, i.e. up and down.
• Horizontally polarized light accelerates the electron right and left.

9. We say a plane wave is linearly polarized if there is no phase
difference between Ex and Ey

11. Circular Polarization
• circular polarization of an electromagnetic wave is a polarization state
in which, at each point, the electromagnetic field of the wave has a
constant magnitude but its direction rotates at a constant rate in a
plane perpendicular to the direction of the wave.

13. • the electric field of light consists of two linear components that are
perpendicular to each other, equal in amplitude, but have a phase
difference of π/2. The resulting electric field rotates in a circle around
the direction of propagation.
• There are two directions of propagation that come with circular
polarization: Right-Hand-Circular (RHC) which follows a clockwise
pattern, and Left-Hand-Circular (LHC) which follows a
counterclockwise pattern.

15. ELLIPTICAL POLARIZATION
• The electric field of light describes an ellipse.
• This results from the combination of two linear components with
differing amplitudes and/or a phase difference that is not π/2.

16. • The two orthogonal linear polarization states that are most important
for reflection and transmission are referred to as p- and s-polarization.
1. P-polarized (from the German parallel) light has an electric field
polarized parallel to the plane of incidence.
2. S-polarized (from the German senkrecht) light is perpendicular to
this plane.
• P polarization is commonly referred to as transverse-magnetic (TM)
• S polarization is also called transverse-electric (TE), as well as sigma-
polarized.
• This is frequently used to relates to the plane of incidence.

19. TASK:
1. What if we have a superposition of left and right circularly polarized
light of equal amplitude?
2. Write down the applications of Polarization