From Reinhard Schinke
From Reinhard Schinke
Jan 14, 2016
From Reinhard Schinke. From Reinhard Schinke. From Reinhard Schinke. From Reinhard Schinke. From Reinhard Schinke. Lasers: N 2 >>N 1. 2. A 23. B 21 W( w ). A 21. B 23 W p ( w ). 1. A 13. 3. Lasers: N 2 >>N 1. 2. Lase. A 23. B 21 W( w ). A 21 slow. B 23 W p ( w ). 1. Pump. - PowerPoint PPT Presentation
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From Reinhard Schinke
From Reinhard Schinke
From Reinhard Schinke
From Reinhard Schinke
From Reinhard Schinke
Lasers: N2>>N1
B21W()
A13
2
1
3
B23Wp() A21 A23
Lasers: N2>>N1
B21W()
A13
fast
2
1
3
B23Wp() A21
slow
A23
Pump
Lase
Nd3+:Y3Al5O12 (YAG)
Cavity—2 mirrors separated by n/2
Lasers characterized by:DirectionalityMonochromaticBrightnessCoherence
Discuss: Threshhold
LinewidthsHomogeneous Broadening:
Affects every molecule the same way
e.g. time energy uncertainty principle and pressure broadening
h 1
sets a minimum linewidth of -1
Expressed as e-t/ decay of final state probability the corresponds after Fourier transform to a Lorentzian lineshape
22
0
2max
4/1
4/
IIL FWHM=
LinewidthsInhomogeneous broadening:
Collection of molecules have a distribution of transition energies. Typically given by statistics of different molecular environments and described by Gaussian functions.
220 2/
max eIIG FWHM=2(2ln2)
e.g. Doppler Broadening M
Tx
m
kT
C 71072ln
22
– Mon Feb 18 Presidents day
– Weds: Rayleigh and Raman Scattering
– Weds Feb 27: Projects Part1
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