Date post: | 19-Dec-2015 |
Category: |
Documents |
View: | 214 times |
Download: | 0 times |
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