Optics and PhotonicsOptics and Photonics

Dr. Kevin HewittDr. Kevin HewittOffice: Dunn 240, 494-2315Office: Dunn 240, 494-2315Lab: Dunn B31, 494-2679Lab: Dunn B31, 494-2679

Kevin.Hewitt@Dal.caKevin.Hewitt@Dal.ca

Friday Sept. 6, 2002Friday Sept. 6, 2002

22

Course InformationCourse Information

Optics is light Optics is light atat work workTextbook: Optics (4Textbook: Optics (4thth edition), Eugene Hecht, $152.39 edition), Eugene Hecht, $152.39Reference: Introduction to Optics, F. & L. Pedrotti, Reference: Introduction to Optics, F. & L. Pedrotti, Description: Two areas will be covered:Description: Two areas will be covered:– Geometrical optics: Geometrical optics: < dimension of aperture/object < dimension of aperture/object– Wave (i.e. physical) optics:Wave (i.e. physical) optics: > dimension of aperture/object > dimension of aperture/object

Selected topics:Selected topics:– What are your areas of interest?What are your areas of interest?– Lasers, holography, fiber optic communication, functions of the Lasers, holography, fiber optic communication, functions of the

eye…eye…

Pre-requisites:Pre-requisites: PHYC 2010/2510 PHYC 2010/2510 andand MATH 2002 MATH 2002

33

Course InformationCourse Information

Grading: Grading: – Problem sets Problem sets 20%20%– MidtermMidterm 20%20%– Oral PresentationOral Presentation 20%20%– Final examFinal exam 40%40%

Problem sets:Problem sets:– 1 per week1 per week– Hand-out/Hand-in every Wednesday (begin Hand-out/Hand-in every Wednesday (begin

Sept. 11)Sept. 11)

44

Class ScheduleClass ScheduleWeekWeek DatesDates TopicTopic Key termsKey terms

11 Sept. 6Sept. 6 The Nature of lightThe Nature of light Wave-particle dualityWave-particle duality

22 Sept. 9-14Sept. 9-14 Geometrical opticsGeometrical optics Huygen’s and Fermat’s principlesHuygen’s and Fermat’s principles

Reflection, refraction, thin lensReflection, refraction, thin lens

33 Sept. 16-21Sept. 16-21 Matrix methods in paraxial Matrix methods in paraxial opticsoptics

System matrix elements, thick System matrix elements, thick lens, cardinal points, Ray transfer lens, cardinal points, Ray transfer matrixmatrix

44 Sept. 23-28Sept. 23-28 Optical instrumentationOptical instrumentation

Optics of the eyeOptics of the eye

Stops, pupils, windows, prisms, Stops, pupils, windows, prisms, cameras, telescopes, cameras, telescopes,

Acuity, correctionsAcuity, corrections

55 Sept. 30-Sept. 30-Oct. 4Oct. 4

Wave equations and Wave equations and superpositionsuperposition

Plane and EM waves, Doppler Plane and EM waves, Doppler effecteffect

66 Oct. 7-12Oct. 7-12 Interference of lightInterference of light Young’s double slit, Dielectric Young’s double slit, Dielectric films, Newton’s ringsfilms, Newton’s rings

77 Oct. 14-19Oct. 14-19 Optical InterferometryOptical Interferometry Michelson, Fabry-Perot, Resolving Michelson, Fabry-Perot, Resolving power, Free spectral range.power, Free spectral range.

55

Class ScheduleClass ScheduleWeeWeekk

DatesDates TopicTopic Key termsKey terms

88 Oct. 21 -26Oct. 21 -26 Fraunhofer diffractionFraunhofer diffraction Single slits, multiple slits, rectangular Single slits, multiple slits, rectangular and circular apertures and circular apertures

99 Oct. 28-Oct. 28-Nov.1Nov.1

GratingsGratings Grating equation, Free Spectral Grating equation, Free Spectral Range, Dispersion, ResolutionRange, Dispersion, Resolution

1010 Nov. 4 - 9Nov. 4 - 9 Polarization of lightPolarization of light Fresnel equations, Jones vector, Fresnel equations, Jones vector, birefringence, optical activity, birefringence, optical activity, productionproduction

1111 Nov. 11 - 16Nov. 11 - 16 Laser basics and Laser basics and applicationsapplications

Einstein’s theory, Laser TweasersEinstein’s theory, Laser Tweasers

1212 Nov. 18 - 23Nov. 18 - 23 Fiber optics & Fourier opticsFiber optics & Fourier optics Bandwidth, attenuation, distortion, Bandwidth, attenuation, distortion, optical data imaging and processingoptical data imaging and processing

1313 Nov. 25 -30Nov. 25 -30 HolographyHolography

Class PresentationsClass Presentations

1414 Dec. 2Dec. 2 Classes endClasses end

1515 Dec. 4 - 14Dec. 4 - 14 Exam periodExam period 3 hour exam3 hour exam

66

Key DatesKey Dates

DateDate ItemItem

September 20September 20 Last Day to RegisterLast Day to Register

October 7October 7 Last Day to Drop without a “w”Last Day to Drop without a “w”

October 14October 14 Thanksgiving DayThanksgiving Day

October 12October 12 Midterm examMidterm exam

November 11November 11 Remembrance dayRemembrance day

November 4November 4 Last Day to drop with a “W”Last Day to drop with a “W”

Nov. 25-30Nov. 25-30 Oral PresentationsOral Presentations

December 2December 2 Classes endClasses end

December 4-14December 4-14 Exam periodExam period

77

Nature of Light (Hecht 3.6)Nature of Light (Hecht 3.6)OpticsOptics

88

Nature of LightNature of Light

ParticleParticle– Isaac Newton (1642-1727)Isaac Newton (1642-1727)– OpticsOptics

WaveWave– Huygens (1629-1695)Huygens (1629-1695)– Treatise on Light (1678)Treatise on Light (1678)

Wave-Particle DualityWave-Particle Duality– De Broglie (1924)De Broglie (1924)

99

Young, Fraunhofer and FresnelYoung, Fraunhofer and Fresnel(1800s)(1800s)

Light as waves!Light as waves!InterferenceInterference– Thomas Young’s (1773-1829) double slit experiment Thomas Young’s (1773-1829) double slit experiment – see see http://members.tripod.com/~vsg/interf.htmhttp://members.tripod.com/~vsg/interf.htm

DiffractionDiffraction– Fraunhofer (far-field diffraction)Fraunhofer (far-field diffraction)– Augustin Fresnel (1788-1827) (near-field diffraction & Augustin Fresnel (1788-1827) (near-field diffraction &

polarization)polarization)

Electromagnetic wavesElectromagnetic waves– Maxwell (1831-1879)Maxwell (1831-1879)

1010

Max Planck’s Blackbody Radiation Max Planck’s Blackbody Radiation (1900)(1900)

Light as particlesLight as particles

Blackbody – absorbs all wavelengths and Blackbody – absorbs all wavelengths and conversely emits all wavelengthsconversely emits all wavelengths

The observed spectral distribution of The observed spectral distribution of radiation from a perfect blackbody did radiation from a perfect blackbody did notnot fit classical theory (Rayleigh-Jeans law) fit classical theory (Rayleigh-Jeans law) ultraviolet catastropheultraviolet catastrophe

1111

0 20

2x107

4x107

6x107

8x107

1x108

T = 5000 K

T = 6000 K

T = 3000 K

Sp

ect

ral R

ad

ian

ce E

xita

nce

(W/m

2 - m

)

Wavelength (m)

M = T

Cosmic black body background radiation, T = 3K.

Rayleigh-Jeans law

1212

Planck’s hypothesis (1900)Planck’s hypothesis (1900)

To explain this spectra, Planck assumed To explain this spectra, Planck assumed light emitted/absorbed in discrete units of light emitted/absorbed in discrete units of energy (quanta),energy (quanta),

E = n hE = n hffThus the light emitted by the blackbody is,Thus the light emitted by the blackbody is,

1

12)(

5

2

kThce

hcM

1313

Photoelectric Effect (1905)Photoelectric Effect (1905)

Light as particlesLight as particlesEinstein’s (1879-1955) explanationEinstein’s (1879-1955) explanation– light as particles = photonslight as particles = photons

Kinetic energy = hƒ - Ф

Electrons

Light of frequency ƒ

Material with work function Ф

1414

Luis de Broglie’s hypothesis (1924)Luis de Broglie’s hypothesis (1924)

Wave and particle pictureWave and particle picture

Postulated that all particles have associated Postulated that all particles have associated with them a wavelength,with them a wavelength,

p

h

For any particle with rest mass mFor any particle with rest mass moo, treated , treated

relativistically,relativistically,42222 cmcpE o

1515

Photons and de BrogliePhotons and de Broglie

For photons mFor photons moo = 0 = 0

E = pcE = pc

Since also E = hfSince also E = hf

f

c

chfh

cEh

p

h

But the relation c = But the relation c = ƒ is just what we expect for ƒ is just what we expect for a harmonic wavea harmonic wave

1616

Wave-particle dualityWave-particle duality

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

Usually, one or the other is most Usually, one or the other is most convenientconvenient

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

1717

Propagation of light: Huygens’ Propagation of light: Huygens’ Principle (Hecht 4.4.2)Principle (Hecht 4.4.2)

E.g. a point source (stone dropped in E.g. a point source (stone dropped in water)water)Light is emitted in all directions – series of Light is emitted in all directions – series of crestscrests and and troughstroughs

Rays – lines perpendicular to wave fronts

Wave front - Surface of constant phase

1818

TerminologyTerminology

Spherical waves – wave fronts are Spherical waves – wave fronts are sphericalspherical

Plane waves – wave fronts are planesPlane waves – wave fronts are planes

Rays – lines Rays – lines perpendicular to wave frontsperpendicular to wave fronts in the in the direction of propagationdirection of propagation

x

Planes parallel to y-z plane

1919

Huygen’s principleHuygen’s principle

Every Every pointpoint on a wave front is a source of on a wave front is a source of secondary wavelets.secondary wavelets.

i.e. particles in a medium excited by i.e. particles in a medium excited by electric field (E) electric field (E) re-radiatere-radiate in all directions in all directions

i.e. in vacuum, E, B fields associated with i.e. in vacuum, E, B fields associated with wave act as wave act as sourcessources of additional fields of additional fields

2020

Huygens’ wave front constructionHuygens’ wave front construction

Given wave-front at tGiven wave-front at t

Allow wavelets to evolve for time Δt

r = c Δt ≈ λ

New wavefront

What about –r direction? See Bruno Rossi Optics. Reading, Mass: Addison-Wesley Publishing Company, 1957, Ch. 1,2

for mathematical explanation

Construct the wave front tangent to the wavelets

2121

Plane wave propagationPlane wave propagation

New wave front is still New wave front is still a plane as long as a plane as long as dimensions of wave dimensions of wave front are >> front are >> λλIf not, edge effects If not, edge effects become importantbecome importantNote: no such thing Note: no such thing as a perfect plane as a perfect plane wave, or collimated wave, or collimated beambeam