Déformation photoinduite dans les films minces contenant des ...

Chapter 3. Microscopic mechanisms at the origin of the photo-induced deformation inazobenzene-containing thin films 97CIRCULARRADIAL(a) (b) (c) (d)(e) (f) (g) (h)pastel-00527388, version 1 - 19 Oct 2010!AZIMUTHAL(i) (j) (k) (l)!E //!E "TOPOGRAPHYFigure 3.31: Matter migration under a Bessel beam. We report the experimental resultsobtained in ref. [20] in the case of radially (a-d), circularly (e-h) and azimuthally(i-l) polarized light.!(a), (e), (i): measured E ⃗ ‖ field intensity spatial distribution on thexy plane; (b), (f), (j): calculated E ⃗ ⊥ field intensity spatial distribution on the xy plane;(c),(g),(k): shear-force topography measurements photoinduced by the correspondinglight field; (d),(h),(l): (top) E ⃗ ‖ calculated (dashed) and measured (solid) intensityprofiles, (bottom) E ⃗ ⊥ calculated (dashed) intensity profile and measured (solid) topographyprofile. Sample = PMMA-DR1, 100 nm thick, light dose = 20 J/cm 2 (0.5 sexposure at a 40 W/cm 2 laser beam, λ = 514 nm).Bessel beamA Bessel beam is characterized by the superposition of two orthogonally polarized periodicfield components, one polarized in the x, y plane ( E ⃗ ‖ ) and the other one polarizedalong the z-axis ( E ⃗ ⊥ ). According to the polarization (radial, circular or azimuthal) theirintensities are described by J0 2 and J 1 2 square Bessel functions, which are half a periodspatially shifted. For example, a radially polarized Bessel beam Figure 3.31(a-b) 25 hasa maximum E ⃗ ⊥ and a zero E ⃗ ‖ intensities in the origin, while for a circularly polarized25 Figure 3.31 has been reproduced from [20].