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Faraday effect

Faraday effect. 1) Passive polarizing elements. 2) Faraday rotation. 3) rotators, isolators, compensators. 4) Magnetic field measurements. 1) Passive polarizing elements. Principle of reciprocity applies. Anisotropic absorption: polarizers.

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Faraday effect

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  1. Faraday effect 1) Passive polarizing elements 2) Faraday rotation 3) rotators, isolators, compensators 4) Magnetic field measurements

  2. 1) Passive polarizing elements Principle of reciprocity applies Anisotropic absorption: polarizers Anisotropic index (crystals) birefringence, waveplates Optical activity = difference in index for the two different circular components Dn of the order of 10-4 Birefringence: Dn of the order of 10-2

  3. 2) Faraday rotation Rotation of the plane of polarization proportional to a magnetic field Resonant effect: J=0 s- s+ m=+1 J=1 m=-1 Difference between sublevels proportional to magnetic field. Dn w

  4. 2) Faraday rotation The dispersion of any line extends very far (Lorentzian) ANY transparent medium has a Faraday effect. Rotation is At 790 nm, for TGG: V = 4.5×103oT−1 m−1 BK7 glass: 150

  5. 3) rotators, isolators, compensators

  6. saturable absorber dye jet TGG Magnetic material of length l: Resolution: 10 nT or Faraday rotation of 8x10-9rad 9 mm TGG 30 nT/Hz Slope sensitivity inversely proportional to size Extracavity pump Femtosecond temporal resolution Intracavity probe Actual measurement l G TGG = Terbium Gallium Garnet

  7. saturable absorber dye jet TGG IPI vs Faraday rotation Resolution: 8x10-9rad 0.3 Hz, for 9 mm TGG IMPOSSIBLE TO MEASURE! 80 MHz B = 10 nT l

  8. l temporal resolution Intensity and time dependence of magnetic material: Measure beat note as a function of position Pump Probe experiment: External pump, internal probe G

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