Transcript Chapter 6 Optoelectronics and Second Edition ISBN-10: 0133081753

Power Point for Optoelectronics and
Photonics: Principles and Practices
Second Edition
A Complete Course in Power Point
Chapter 6
ISBN-10: 0133081753
Second Edition Version 1.011
[14 January 2013]
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Copyright Information and Permission: Part I
This Power Point presentation is a copyrighted supplemental material to the textbook
Optoelectronics and Photonics: Principles & Practices, Second Edition, S. O. Kasap,
Pearson Education (USA), ISBN-10: 0132151499, ISBN-13: 9780132151498. © 2013
Pearson Education. Permission is given to instructors to use these Power Point slides in
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PEARSON
Copyright Information and Permission: Part II
This Power Point presentation is a copyrighted supplemental material to the textbook
Optoelectronics and Photonics: Principles & Practices, Second Edition, S. O. Kasap,
Pearson Education (USA), ISBN-10: 0132151499, ISBN-13: 9780132151498. © 2013
Pearson Education. The slides cannot be distributed in any form whatsoever,
electronically or in print form, without the written permission of Pearson Education. It is
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From: S.O. Kasap, Optoelectronics and Photonics: Principles
and Practices, Second Edition, © 2013 Pearson Education, USA
Chapter 6 Polarization and Modulation
of Light
Christiaan Huygens (1629 – 1695)
(Morphart Creations Inc./Shutterstock.com)
Chapter 6
Polarization and Modulation of Light
Sailors visiting Iceland during the 17th century
brought back to Europe calcite crystals
(Iceland spar) which had the unusual property
of showing double images when objects were
viewed through it. The Danish scientist
Rasmus Bartholin (Erasmus Bartholinus)
described this property in 1669 as the effect of
double refraction, and later Christiaan Huygens
(1629 - 1695), a Dutch physicist, explained this
double refraction in terms of ordinary and
extraordinary waves. Christiaan Huygens
made many contributions to optics and wrote
prolifically on the subject. (Courtesy of AIP
Emilo Segrè Visual Archives.)
(Morphart Creations
Inc./Shutterstock.com)
“As there are two different refractions, I
conceived also that there are two different
emanations of the waves of light...”
Christiaan Huygens
S.O. Kasap, Optoelectronics and Photonics: Principles and Practices, Second Edition, © 2013 Pearson Education
© 2013 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This publication is protected by Copyright and written permission should be obtained from the
publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or
likewise. For information regarding permission(s), write to: Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.
Chapter 6
Polarization and Modulation of Light
LiNbO3 based fiber coupled phase and amplitude modulators
(© JENOPTIK Optical System GmbH)
S.O. Kasap, Optoelectronics and Photonics: Principles and Practices, Second Edition, © 2013 Pearson Education
© 2013 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This publication is protected by Copyright and written permission should be obtained from the
publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or
likewise. For information regarding permission(s), write to: Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.
Linearly Polarized Light
(a) A linearly polarized wave has its electric field oscillations defined along a line
perpendicular to the direction of propagation, z. The field vector E and z define a plane of
polarization. (b) The E-field oscillations are contained in the plane of polarization. (c) A
linearly polarized light at any instant can be represented by the superposition of two fields
Ex and Ey with the right magnitude and phase
Circularly Polarized Light
A right circularly polarized light. The field vector E is always at
right angles to z, rotates clockwise around z with time, and traces
out a full circle over one wavelength of distance propagated.
The Phase Difference f
Ex = Exocos(wt - kz )
Ey = Eyocos(wt - kz + f)
Examples of linearly, (a) and (b), and circularly polarized light (c) and (d);
(c) is right circularly and (d) is left circularly polarized light (as seen when
the wave directly approaches a viewer)
Elliptically Polarized Light
(a) Linearly polarized light with Eyo = 2Exo and f = 0. (b) When f = p/4 (45°), the light is
right elliptically polarized with a tilted major axis. (c) When f = p/2 (90°), the light is
right elliptically polarized. If Exo and Eyo were equal, this would be right circularly
polarized light.
Polarizers
A polarizer allows field oscillations along a
particular direction transmission axis to pass through
Transmission axis (TA)
The wire grid-acts as a polarizer
There are many types of polarizers
Malus’s Law
I(q) = I(0)cos2q
Randomly polarized light is incident on a Polarizer 1 with a transmission axis TA 1. Light emerging
from Polarizer 1 is linearly polarized with E along TA1, and becomes incident on Polarizer 2 (called
the analyzer) with a transmission axis TA2 at an angle q to TA1. A detector measures the intensity
of the incident light. TA1 and TA2 are normal to the light direction.
Optical Anisotropy
Photo by SK
A line viewed through a cubic sodium chloride (halite) crystal
(optically isotropic) and a calcite crystal (optically anisotropic)
Optically Isotropic Materials
Liquids, glasses and cubic crystals
are optically anisotropic
The refractive index is the same in all directions
for all polarizations of the field
Sodium chloride (halite) crystal
Photo by SK
Many crystals are optically anisotropic
They exhibit birefringence
This line is due to the “extraordinary wave”
The calcite crystal has two refractive
indices
The crystal exhibits double refraction
This line is due to the “ordinary wave”
Photo by SK
A calcite crystal
Uniaxial Birefringent Crsytal
Photo byaxes,
SK
Two polaroid analyzers are placed with their transmission
along
Images
viewed
through
a calcite
crystal to
haveeach
orthogonal
polarizations.
Two polaroid
analyzers are
the
long
edges,
at
right
angles
other.
The
ordinary
ray,
placed with their transmission axes, along the long edges, at right angles to each other. The ordinary
undeflected,
goes
left polarizer
the
extraordinary
ray, undeflected,
goes through
through the the
left polarizer
whereas thewhereas
extraordinary
wave,
deflected, goes
through the right
polarizer.
The two
waves
therefore
have orthogonal
polarizations
wave, deflected,
goes
through
the
right
polarizer.
The two
waves
therefore have orthogonal polarizations.
Principal refractive indices of some optically isotropic and anisotropic crystals
(near 589 nm, yellow Na-D line)
Optically isotropic
Uniaxial - Positive
Glass (crown)
Diamond
Fluorite (CaF2)
Ice
Quartz
Rutile (TiO2)
Uniaxial - Negative
Biaxial
Calcite (CaCO3)
Tourmaline
Lithium niobate
(LiNbO3)
Mica (muscovite)
n = no
1.510
2.417
1.434
no
ne
no
ne
n1
n2
1.309
1.5442
2.616
1.658
1.669
2.29
1.5601
1.3105
1.5533
2.903
1.486
1.638
2.20
1.5936
n3
1.5977
Optical Indicatrix
(a) Fresnel's ellipsoid (for n1 = n2 < n3; quartz) (b) An EM wave propagating along OP at
an angle q to the optic axis.
Optical Indicatrix
1
cos q sin q

+
2
2
2
ne (q )
no
ne
2
2
Wave Propagation in a Uniaxial Crystal
Eo = Eo-wave and Ee = Ee-wave (a) Wave propagation along the optic axis. (b)
Wave propagation normal to optic axis
Power Flow in Extraordinary Wave
(a) Wavevector surface cuts in the xz plane for o- and e-waves. (b) An extraordinary
wave in an anisotropic crystal with a ke at an angle to the optic axis. The electric field is
not normal to ke. The energy flow (group velocity) is along Se which is different than ke.
Calcite Rhomb
An EM wave that is off the optic axis of a calcite crystal splits into two waves called
ordinary and extraordinary waves. These waves have orthogonal polarizations and travel
with different velocities. The o-wave has a polarization that is always perpendicular to
the optical axis.
Calcite is a uniaxial birefringent crystal
Photo by SK
Two polaroid analyzers are placed with their transmission axes, along
Images viewed through a calcite crystal. Two polaroid analyzers are placed with their transmission
the
long edges, at right angles to each other. The ordinary ray,
axes, along the long edges, at right angles to each other. The ordinary ray, undeflected, goes
undeflected,
goes
through
the
polarizer
whereas
through the left
polarizer
whereas
the left
extraordinary
wave,
deflected, the
goes extraordinary
through the right
polarizer.
The through
two waves therefore
have
orthogonal polarizations.
wave, deflected,
goes
the right
polarizer.
The two waves
therefore have orthogonal polarizations.
Retarder Plate
(a) A birefringent crystal plate with the optic axis parallel to the plate surfaces. (b)
A birefringent crystal plate with the optic axis perpendicular to the plate surfaces.
Retarder Plate
A retarder plate. The optic axis is parallel to the plate face. The o- and ewaves travel in the same direction but at different speeds
Retarder Plate
f
2p

( ne - no ) L
A retarder plate. The optic axis is parallel to the plate face. The o- and e-waves
travel in the same direction but at different speeds
f
2p

( ne - no ) L
Input and output polarizations of light through (a) a half-wavelength plate and
(b) through a quarter-wavelength plate.
Soleil-Babinet Compensator
Courtesy of Thorlabs
Soleil-Babinet Compensator
Soleil-Babinet compensator
Soleil-Babinet Compensator
Phase change of E1
f1 
2p

(ne d + no D)
Phase change of E2
f2 
2p

(no d + ne D)
f = f2 - f1
f
2p

(ne - no )( D - d )
Wollaston Prism
The Wollaston prism is a beam polarization splitter. E1 is orthogonal to
the plane of the paper and also to the optic axis of the first prism. E2 is in
the plane of the paper and orthogonal to E1.