Lecture 8: Laser amplifiers

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Spectral lineshape For each particular resonant transition between two energy levels, there is a characteristic lineshape function g() ^ of finite linewidth that characterizes the optical processes associated with the transition. The lineshape function is generally normalized as ĝ() d ĝ() d 1 0 0 ĝ() 2ĝ() Area = 1 12 12
Homogeneous broadening If all of the atoms in a material that participate in a resonant interaction associated with the energy levels |1> and |2> are indistinguishable, their responses to an electromagnetic field are characterized by the same resonance frequency 21 and the same relaxation constant 21 . In such a homogeneous system, the physical mechanisms that contribute to the linewidth of the transition affect all atoms equally. Spectral broadening due to such mechanisms is called homogeneous broadening. Previously (in Lect. 2), we discussed that such homogeneously broadened systems can be described as the damped response characterized by a single resonance 13 frequency and a single relaxation constant.
Page 1 and 2: Lecture 8: Laser amplifiers Opt
Page 3 and 4: Optical transitions 3
Page 5 and 6: Photon-matter interaction processes
Page 7 and 8: Three basic photon-matter interacti
Page 9 and 10: Probability per second of a spontan
Page 11: Spectral lineshape The spectra
Page 15 and 16: Inhomogeneous broadening Howeve
Page 17 and 18: Transition rates The transiti
Page 19 and 20: Transition rates For the upward tr
Page 21 and 22: Transition rates The total induce
Page 23 and 24: Blackbody radiation A system und
Page 25 and 26: Planck’s law of blackbody radiati
Page 27 and 28: Transition rates In thermal equili
Page 29 and 30: Boltzmann distribution Energy E E 2
Page 31 and 32: Transition rates Therefore, the s
Page 33 and 34: Transition cross section For the
Page 35 and 36: Optical absorption and amplificatio
Page 37 and 38: Optical absorption and amplificatio
Page 39 and 40: Resonant optical susceptibility Fo
Page 41 and 42: Resonant optical susceptibility Th
Page 43 and 44: Population inversion 43
Page 45 and 46: Population inversion A nonequilibr
Page 47 and 48: Rate equations The net rate of chan
Page 49 and 50: Population inversion Population in
Page 51 and 52: Two-level systems No matter how a
Page 53 and 54: Two-level systems Take the upward
Page 55 and 56: Two-level systems Intuitively, th
Page 57 and 58: Quasi-two-level systems By pumpi
Page 59 and 60: Population inversion in three-level
Page 61 and 62: Three-level systems The parameter
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Four-level systems pump h p Nonradi
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Neodymium-doped glass Nd 3+ :glass
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Coherent optical amplifiers Gain, n
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Coherent light amplification As
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Population inversion Light tran
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Real coherent amplifiers Real
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Gain and bandwidth The wave is am
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Gain coefficient As the incident
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Gain coefficient The coefficient
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Gain bandwidth The dependence
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Phase‐shift coefficient The las
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Rate equations 2 R 2 1/ 21 = 1/ sp
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Rate equations in the absence of am
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Rate equations in the presence of a
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Four-level pumping Pump R Laser W i
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Four-level pumping In most four-le
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Four-level pumping Under these c
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Three-level pumping Rapid decay S
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Three-level pumping The population
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Three-level pumping The dependence
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Saturated gain in homogeneously bro
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Gain coefficients This represents t
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Amplified spontaneous emission T
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Amplifier noise The ASE of a la
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Lecture 8: Laser amplifiers

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