Announcements 4/6/12
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

Prayer
Exam 3 ends tomorrow
I’ll be on the radio 5 pm
tomorrow with the Utah
Baroque Ensemble: 89.1 FM
or Sirius XM 143 (BYU
radio). An hour of classicalstyle choral music, pieces
dating from ~1600 to
~2000.
Close to Home
Reading Quiz
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Who developed the “A and B” coefficients?
a. Avogadro and Boltzmann
b. Bohr
c. Einstein
d. Fermi
e. Plank
Reading Quiz
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Which of these processes is not one considered
in Einstein’s A & B coefficient analysis?
a. spontaneous absorption
b. stimulated absorption
c. spontaneous emission
d. stimulated emission
Two Level System: Three Processes
Stimulated
Absorption
Emission Emission
Energy
Energy
(light,
(light)
electrical,
etc.)
light
light: incident + more
A & B for a Two Level System
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and application to lasers
Lasers
Image & list
from Wikipedia
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Principal components:
1.
2.
3.
4.
5.
Gain medium
Laser pumping energy
High reflector
Output coupler
Laser beam
From Saleh &
Teich,
Fundamentals
of Photonics
(2007)
Lasers!!
From Wikipedia
Semiconductor Alloys
From Saleh & Teich, Fundamentals of Photonics (2007)
Bandgap Engineering
Quotes from web page author
From http://www.tf.uni-kiel.de/matwis/amat/semi_en/kap_5/backbone/r5_1_4.html