光電工程二 optoelectronic engineering...

光電工程二

Optoelectronic Engineering II http://mx.nthu.edu.tw/mingchang/

Instructor: 陳明彰LAs:??

Today’s class

Why are we here…?What’s this class about ?What do we need to do ?How do we plan on doing it ?

http://mx.nthu.edu.tw/mingchang/

Lots of information posted on the web.Check frequently for changes!

What we are going to cover this semester?

Grading• In-class participation (5%)

– Participation only – Graded (Reading quizzes, occasional graded clicker question)

• Homework (45%) (most of learning, collaboration helps but you need to write your own solutions) Late HW will not be accepted, but I will drop your lowest one HW. No other freebies!

• Project (15 %) May 24: 1:20pm

• Exams (35%)– (15% midterm/ 20% final): 1. April 19: 1pm-3:20pm.

2. June 14 : 1pm – 3:20 pm.– Final (30%): Jun. 12: 12:30pm – 3:30 pm

You must be able to make these dates so reserve this time on your calendar! If you need special accommodations: See me!

Note: In-class participation and weekly homework make up 40% of final grade. Grade strongly depends on showing up for class, doing reading, and doing homework every week.

Milestones

Comb laserFrequency stabilization/Laser

Light guided by Fibers

Blue Diode

Laser TweezersLaser cooling/ Laser

Holography 3D Imaing/Laser

Precision Measurement

CHEM

Super-resolutionImaging / Laser

Ultrafast camera / Laser

Trad’l Model of EducationInstruction viatransmission Individual (you!)Content

11

Course Transformation with LAs

Otero et al, Science 2006

Learning only comes as result of your effort!1. Reading before class- introduce ideas and terms.2. Analysis and discussion in class- explore, develop

basic ideas and understanding.3. Master and retain ideas through use in

extensive HW (4-6 hrs/wk)(collaboration good, but submit own work)

Model for learning

Learning only comes as result of your effort!

Constant efforts

(Homework, reading,

disussions …)

degradePatient:T.R.Schibli

Homework

Reading assignments:• For every class (typically 2 assignments per week).• Quizzes on reading assignments will be part of your

final grades

Written Homework:• Weekly. (Usually due in the class on Thursday.)• See class and course homepage for assignments!• Late HW will not be accepted! I will drop your

lowest (one) HW score, but no other freebies.

Written Homework:

Superposition

Temporal-­‐Spatial  Waves

Freezing  Time

Light source

Electromagnetic  waves

x

E

E-field (for a single color):

E(x,t) = E0 sin[ (2πx/λ ) ̶ ωt +φ]

λE0

φ

λ = 2πc/ω,

E

Bx

Wavelength λ of visible light is: λ ~ 350 nm … 750 nm.

ω = 2πf = 2π/T

Free  physics  simulations!http://phet.colorado.edu

Wave interference.jarRadio Waves.jar

Mirrors

Light source

EM-­‐Waves  in  an  interferometer

Light source

Semi-transparentmirror

L

L

Constructive  interference

=+

Screen:

?

Esum(x,t)  =  ½  ·∙E0  sin(ωt+2πx/λ +φ)  +  ½  ·∙E0  sin(ωt+2πx/λ +φ)  =  ?

=            E0  sin(ωt+2πx/λ +φ) =      Elight  source(x,t)

Light sourceLight source

L

L

Unequal  arm  lengths

ΔL/2ΔL

+ΔL/2

Destructive  interference

=+

Screen:

?

Esum(x,t)  =  ½  ·∙E0  sin(ωt+2πx/λ +φ)  +  ½  ·∙E0  sin(ωt+2π(x+Δx)/λ +φ)

=  ½  ·∙E0  sin(ωt+2πx/λ +φ)  -­‐ ½  ·∙E0  sin(ωt+2πx/λ +φ)  =  0

if Δx = λ / 2:sin(x+π) = - sin(x)

Light sourceLight source

Moving  mirror:  What  do  you  see?

Screen

ΔL

ΔL

Intensity

λ/2

Light sourceLight source

Tilted  mirror:  What  do  you  see?Fringes!

Screen

Hint

Math  Exercise

=?

=?

cos(x)+cos(x+phi)

http://mx.nthu.edu.tw/~mingchang/Courses/OP/Lecture_pdf/interference01.mp4

1.5cos(x)+cos(x+phi)

http://mx.nthu.edu.tw/~mingchang/Courses/OP/Lecture_pdf/interference02.mp4

Discussion

A*cos(x)+B*cos(x+phi)

Discuss  the  visibility  ([Imax-­‐Imin]/ Imax+Imin)  as  a  function  of  amplitude  (A  &  B)?

Case  I  :  B=A

Case  II  :  B=0.5A

Sum  two  waves  with  different  wavelength  ?@@

cos(1.1x)+cos(x)k1=1.1 k2=1

Period  K

cos(1.2x)+cos(x)k1=1.2 k2=1

Period  K

Relation  between  k1,  k2 and  K?

Discussion  

Relation  between  k1,  k2 and  K?