Download Lasers

Modern Optics
PHY485F/1485F
www.physics.utoronto.ca/~phy485/ModOpt/
Robin Marjoribanks
McLennan Physics 1104C
[email protected]
What makes this course
important?
foundation course in modern (quantum) optics
basic literacy in a modern, active area of physics
fundamental science, concepts, understanding
a subject of technology that supports many others
an extremely active, intense area of current
research
numerous Nobel prizes in the last decade
Topics
 laser as a pivot-point
 look backwards from invention to classical optics
needed to understand how the laser tailors light,
 forward to the quantum optics explosion that has
followed
 basic optics
 diffraction theory
 gaussian beams
 laser resonators
 semiclassical laser theory
 ultrafast pulse generation
 a selection of currently active research topics:
 laser cooling, photonic bandgap structures, extreme
optics, quantum information and other topics
The Laser Oscillator
Laser oscillators are built in a Fabry-Perot resonator
W. Silvfast
http://cord.org/step_online/st1-5/st15ttl.htm
 solutions are standing waves in this laser cavity
 spectrum of possible frequencies satisfy:
wn = n 2π c / L
= n wo
L is the cavity length
c is speed of light
 these modes may each have their own amplitude En
thus the optical field in the cavity can be written:
En ei(nwot+f(n))
In a free cavity, with random f(n), we get ‘wild’ light. In a cavity where
we make f(n)=0, we lock the modes together
Ultrafast Ti:sapphire laser
 Kerr effect makes intense pulses ‘self-focus’ slightly




intense pulses pass better through aperture, where weak ones blocked
alters stability of cavity slightly, favoring intense pulses
also can affect deflection of beam, to same effect
modelocking can start from mechanical vibration: ‘magic modelocking’
Er-fiber laser
output:
1550 nm
100 fs
2–40 mW
pump:
980 nm diode
60 mW min
fiber coupled
modelocking:
Kerr ellipserotation
polarizer
discrimination
dispersion
2 kinds of fiber
opposite GVD
pump input coupler
(WDM 980/ 1550nm )
optical pump
(980nm diode laser)
pigtail fiberoptic leads
pigtail fiberoptic leads
Er-doped fiber
(5m length)
pigtail fiberoptic leads
polarization
controller
Faraday
isolator/polarizer
polarization
controller
pigtail fiberoptic leads
pigtail fiberoptic leads
output coupler
Controller for thermoelectric cooler on pump
partial recompression
MetroCor fiber length
electrical feedthroughs
fiber optic feedthroughs
Approach
multiple resources
textbook
lectures
online materials: demos, applications
office hours
other texts
study/work groups
all are needed
each has particular advantages
Lectures
will concentrate on what lectures do best
won’t just lead you through the textbook
will provide interaction and feedback that
books cannot
will provide demonstrations and
animations
will depend on you having read also
Textbook
“Modern Optics and Lasers” course-notes
by sign-up (please use index-cards)
optional (cheap): “Introduction to Modern
Optics” by Grant R. Fowles (get online
errata correcting numerous errors)
reference: “Optics” (4th edition), Hecht
reference: “Lasers” by P.W. Milonni and
J.H. Eberly (Wiley).
Office Hours
Professor Marjoribanks
Wednesdays 2–3 pm (OK?)
MP1104C
marker to be determined
Contact
I’ll email using your official registered
U of T email address (e.g.,
[email protected])
problem set corrections, class
announcements, reminders may go there
you’re responsible for email
Problem sets
Problem set due dates (posted on web)
PS#1 - due 2 October
PS#2 - due 18 October
Midterm Test: 25 October 2007, 5-7 pm OK?
PS#3 - due 15 November
PS#4 - due 6 December (zero extensions)
Group seminar presentations 1 December 10-5pm
solutions posted on course web-site
late policy: 20% off per day
zero, once solutions are posted (~3 days)
Marking scheme
Term work:
4 problem sets (best 3 out of 4)
seminar group presentation (1 Dec)
term test
30%
10%
60%
100%
Final exam
final exam
Course mark:
100%
60/40 flip-flop
Midterm test – only impossibles
23 Monday 24 Tues
25 Wed
26 Thurs
27 Friday
9-10
10-11
xxxxx
xxxxx
11-12
12-1pm
1-2
2-3
3-4
xxxxx
xxxxx
4-5
√
5-6
√
1
3
3
3
6-7
1
1
2
3
2
7-8
1
1
1
1.5
1
1
1.5
1
8-9
Colloq