Physical Physical OpticsOpticsProfessor 송 석호, Physics Department (Room #36-401)

2220-0923, 010-4546-1923, shsong@hanyang.ac.kr

Office Hours Mondays 10:00-12:00, Wednesdays 10:00-12:00

Grades Midterm Exam 30%, Final Exam 30%, Homework 20%, Attend 10%

Textbook Introduction to Optics (F. Pedrotti, Wiley, New York, 1986)

Homepage http://optics.hanyang.ac.kr/~shsong

Reference web: Lecture note of Prof. Robert P. Lucht, Purdue University

OpticsOptics

www.optics.rochester.edu/classes/opt100/opt100page.html

Light is a Ray (Geometrical Optics)

1. Nature of light2. Production and measurement of light3. Geometrical optics4. Matrix methods in paraxial optics5. Aberration theory6. Optical instrumentation27. optical properties of materials

Light is a Wave (Physical Optics)

8. Wave equations9. Superposition of waves10. Interference of light11. Optical interferometry12. Coherence13. Holography14. Matrix treatment of polarization15. Production of polarized light

Course outlineCourse outline

Light is a Wave (Physical Optics)

25. Fourier optics16. Fraunhofer diffraction17. The diffraction grating18. Fresnel diffraction19. Theory of multilayer films20. Fresnel equations* Evanescent waves

26. Nonlinear optics

Light is a Photon (Quantum Optics)

21. Laser basics22. Characteristics of laser beams23. Laser applications24. Fiber optics

Also, see Figure 2-1, Pedrotti

(Genesis 1-3) And God said, "Let there be light," and there was light.

A Bit of HistoryA Bit of History

1900180017001600 200010000-1000

“...and the foot of it of brass, of the lookingglasses of the women

assembling,” (Exodus 38:8)

Rectilinear Propagation(Euclid)

Shortest Path (Almost Right!)(Hero of Alexandria)

Plane of IncidenceCurved Mirrors(Al Hazen)

Empirical Law of Refraction (Snell)

Light as PressureWave (Descartes)

Law of LeastTime (Fermat)

v

More Recent HistoryMore Recent History

2000199019801970196019501940193019201910

Laser(Maiman)

Quantum Mechanics

Optical Fiber(Lamm)

SM Fiber(Hicks)

HeNe(Javan)

Polaroid Sheets (Land)Phase Contrast (Zernicke)

Holography (Gabor)

Optical Maser(Schalow, Townes)

GaAs(4 Groups)

CO2(Patel)

FEL(Madey)

Hubble Telescope

Speed/Light (Michaelson)

Spont. Emission (Einstein)

Many New Lasers

Erbium Fiber Amp

Commercial Fiber Link (Chicago)

(Chuck DiMarzio, Northeastern University)

LasersLasers

Nature of LightNature of Light

ParticleParticle

Isaac Newton (1642Isaac Newton (1642--1727)1727)

OpticsOptics

WaveWave

Huygens (1629Huygens (1629--1695)1695)

Treatise on Light (1678)Treatise on Light (1678)

WaveWave--Particle DualityParticle Duality

De De BroglieBroglie (1924)(1924)

Maxwell -- Electromagnetic waves

PlanckPlanck’’s hypothesis (1900)s hypothesis (1900)

Light as particlesLight as particlesBlackbody Blackbody –– absorbs all wavelengths and conversely emits absorbs all wavelengths and conversely emits all wavelengthsall wavelengthsLight emitted/absorbed in discrete units of energy (quanta),Light emitted/absorbed in discrete units of energy (quanta),

E = n h fE = n h fThus the light emitted by the blackbody is,Thus the light emitted by the blackbody is,

⎟⎟⎠

⎞⎜⎜⎝

⎛

−=

1

12)( 52

kThc

e

hcMλλ

πλ

Photoelectric Effect (1905)Photoelectric Effect (1905)

Light as particlesLight as particlesEinsteinEinstein’’s (1879s (1879--1955) explanation1955) explanation

light as particles = photonslight as particles = photons

Kinetic energy = hƒ - Ф

Electrons

Light of frequency ƒ

Material with work function Ф

WaveWave--particle duality (1924)particle duality (1924)

All phenomena can be explained using either All phenomena can be explained using either the wave or particle picturethe wave or particle picture

Usually, one or the other is most convenientUsually, one or the other is most convenient

In In OPTICSOPTICS we will use the wave picture we will use the wave picture predominantlypredominantly

ph

=λ

Nature of LightNature of Light

Particle : Isaac Newton (1642Particle : Isaac Newton (1642--1727)1727)

Wave : Christian Huygens (1629Wave : Christian Huygens (1629--1695)1695)

WaveWave--Particle Duality : Luis De Particle Duality : Luis De BroglieBroglie (1924)(1924)

All phenomena can be explained using All phenomena can be explained using either the wave or particle pictureeither the wave or particle pictureUsually, one or the other is most convenientUsually, one or the other is most convenientIn In OPTICSOPTICS we will use the wave picture we will use the wave picture predominantlypredominantly

LetLet’’s warms warm--upup

일반물리일반물리

전자기학전자기학

Question Question

How does the light propagate through a glass medium?

(1) through the voids inside the material.(2) through the elastic collision with matter, like as for a sound.(3) through the secondary waves generated inside the medium.

Construct the wave front tangent to the wavelets

Secondaryon-going wave

Primary incident wave

What about –r direction?

Electromagnetic WavesElectromagnetic Waves

0εQAdE =⋅∫

0=⋅∫ AdB

dtdsdE BΦ−=⋅∫

dtdisdB EΦμε+μ=⋅∫ 000

Gauss’s Law

No magnetic monopole

Faraday’s Law (Induction)

Ampere-Maxwell’s Law

Maxwell’s Equation

Maxwell’s Equation

Gauss’s Law

No magnetic monopole

Faraday’s Law (Induction)

Ampere-Maxwell’s Law

∫∫∫ ερ

=⋅∇=⋅ dvdvEAdE0

0=⋅∇=⋅ ∫∫ dvBAdB

∫∫∫ ⋅−=⋅×∇=⋅ AdBdtdAdEsdE

∫∫

∫∫

⋅εμ+⋅μ=

Φεμ+μ=⋅×∇=⋅

AdEdtdAdj

dtdiAdBsdB E

000

000

tEjB∂∂

εμ+μ=×∇ 000

djtE=

∂∂

ε0 ( )djjB +μ=×∇ 0

0ερ

=⋅∇ E⇒

0=⋅∇ B⇒

tBE∂∂

−=×∇⇒

⇒

⇒

Wave equationsWave equations

tBE∂∂

−=×∇tEB∂∂

=×∇ 00εμ

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

−∂∂

=×∇∂∂

=×∇×∇tB

tE

tB 0000 εμεμ

( ) BB 2−∇=×∇×∇ kzjyix ˆˆˆ ∂∂

+∂∂

+∂∂

=∇

( ) ( ) BBBB 22 −∇=∇−⋅∇∇=×∇×∇( ) ( ) ( )CBABCACBA ⋅−⋅=××

2

2

002

tBB

∂∂

=∇ εμ

2

2

002

tEE

∂∂

=∇ εμ

022

002

2

=∂∂

−∂∂

tB

xB εμ

022

002

2

=∂∂

−∂∂

tE

xE εμ

Wave equations

In vacuum

Scalar wave equationScalar wave equation

2 2

0 02 2 0x tμ ε∂ Ψ ∂ Ψ− =

∂ ∂

0 cos( )kx tωΨ = Ψ −

02002 =ωεμ−k cvk

≡==00

1εμ

ωSpeed of Light

smmc /103sec/1099792.2 88 ×≈×=

Transverse ElectroTransverse Electro--Magnetic (TEM) wavesMagnetic (TEM) waves

BEtEB ⊥⇒∂∂

εμ−=×∇ 00

Electromagnetic Wave

Energy carried by Electromagnetic WavesEnergy carried by Electromagnetic Waves

Poynting Vector : Intensity of an electromagnetic wave

BES ×=0

1μ

2

0

2

0

0

1

1

BcEc

EBS

μ=

μ=

μ=

(Watt/m2)

⎟⎠⎞

⎜⎝⎛ = c

EB

202

1 EuE ε=Energy density associated with an Electric field :

2

021 BuB μ

=Energy density associated with a Magnetic field :

n1n2

Reflection and Refraction

11 θ′=θReflected ray

Refracted ray 2211 sinsin θθ nn =

Smooth surface Rough surface

Reflection and Refraction

00εμμε

==vcnIn Media,

Interference & Diffraction

Reflection and Interference in Thin Films Reflection and Interference in Thin Films

• 180 º Phase changeof the reflected light by a media with a larger n

• No Phase changeof the reflected light by a media with a smaller n

Interference in Thin Films

tn1

Phase change: π

n2 Phase change: π

n2 > n1

λ=λ==δ1

12

nmmt n

Bright ( m = 1, 2, 3, ···)

( ) ( )λ+=λ+==δ1

21

21

12

nmmt n

Bright ( m = 0, 1, 2, 3, ···)

tnPhase change: π

No Phase change

( ) ( )λ+=λ+==δn

mmt n 21

212

λ=λ==δnmmt n2

Bright ( m = 0, 1, 2, 3, ···)

Dark ( m = 1, 2, 3, ···)

InterferenceYoung’s Double-Slit Experiment

Interference

The path difference

λ=θ=δ msind( )λ+=θ=δ 21msind

⇒ Bright fringes m = 0, 1, 2, ····

⇒ Dark fringes m = 0, 1, 2, ····

The phase differenceλ

θπ=π⋅

λδ

=φsind22

θ=−=δ sindrr 12

Hecht, Optics, Chapter 10

Diffraction

Diffraction

Diffraction GratingGrating

Diffraction of XDiffraction of X--rays by Crystals rays by Crystals

d

θθ

θ

dsinθ

Incidentbeam

Reflectedbeam

λθ md =sin2 : Bragg’s Law

Regimes of Optical DiffractionRegimes of Optical Diffraction

d > λ

Far-fieldFraunhofer

Near-fieldFresnel

Evanescent-fieldVector diff.