Excitation of Localized Modes in Active Random Media

1
Excitation of Localized Modes in Active Random
Media

• M. Pacilli, P. Sebbah and C. Vanneste
• Laboratoire de Physique de la Matière Condensée
• CNRS UMR 6622 Université de Nice-Sophia
  Antipolis

2
Passive Medium
Scatterers
Matrix

• n2 2
• ? 40
• Ø 120 nm

• n1 1

L 5.5 µm
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Anderson Localization
Localized Modes
4
Anderson Localization (2)
profile of mode b E(r)
? 0.5 µm
5
Anderson Localization (3)
6
Laser Equations
Maxwell Equations
Rate Equations
Polarization Equation
4
3
Pump
Laser transition
?l
Wp
2
1
7
Random Laser (1)
Single mode Laser
Dynamic signature
Spectral signature
Spatial signature
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Random Laser (2)
Single mode Laser
Localized modes (passive medium)
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Random Laser (3)
Multimode Laser
Localized modes (passive medium)
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Random Laser (4)
Selective excitation
Localized modes (passive medium)
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Random Laser (5)
Selective excitation
-?NN3-N2
Localized modes (passive medium)
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Random Laser (6)
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Summary

• Laser modes are identical to eigenstates of the
  passive media.
• Localized modes act as  distributed feedback
  random cavities .
• Local pumping allows selective excitation of
  laser modes.
• C. Vanneste and P. Sebbah, Phys. Rev. Lett.
  183903 (2001)