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Déformation photoinduite dans les films minces contenant des ...

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Chapter 3. Microscopic mechanisms at the origin of the photo-induced deformation inazobenzene-containing thin <strong>films</strong> 70yy! !"! !"zxzxû //= ˆx!u !=E y ŷ + E z ẑ( E y ) 2 + ( E z ) 2Figure 3.11: New coordinates.pastel-00527388, version 1 - 19 Oct 2010field projection on the x-axis ⃗ E x g,tot is always Λ/2 spatially shifted 7 with respect to boththe y- and z- components ⃗ E y g,tot , ⃗ E z g,tot, which instead have the same spatial phase 8 .The spatial distribution of the polarization leads us to choose a suitable <strong>des</strong>cription forthe interference light field. Considering the polarization ang<strong>les</strong> ϕ 1 = −ϕ 2 = ϕ and equalinterfering beam amplitu<strong>des</strong> E 0 g1 = E0 g2 = E0 g the total light field is 9 :⃗E g,tot (⃗r, t) = ⃗ E 0 g1cos(ωt + kn g (xsinθ g + zcosθ g )) (3.11)+ ⃗ E 0 g2cos(ωt + kn g (−xsinθ g + zcosθ g ))= E 0 g+ E 0 g⎛⎜⎝⎛⎜⎝−sinϕ cosθ g−cosϕ⎞⎟⎠ cos(ωt′ )sinϕsinθ g⎞sinϕ cosθ g−cosϕ ⎟⎠ cos(ωt′ − 2φ x )sinϕ sinθ gwhere we have used:7 Where Λ ≃ 830 nm is the interference pattern spatial period.8 As shown in eq. 2.28-2.30, see also Appendix A.9 See Appendix A.ωt + n g kzcosθ g = ωt ′ (3.12)φ x = n g kxsinθ g = πxΛ(3.13)

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