Dresden 2017 – wissenschaftliches Programm
CPP 49.11: Poster
Mittwoch, 22. März 2017, 18:30–21:00, P2-OG1
Large-Area Surface Relief Gratings on Thin Films of Azobenzene-Containing Molecular Glasses — •Stefan Hartung1, Lothar Kador1, Andreas Schedl2, Klaus Kreger2, and Hans-Werner Schmidt2 — 1University of Bayreuth, Institute of Physics and BIMF, 95440 Bayreuth, Germany — 2University of Bayreuth, Macromolecular Chemistry I, 95440 Bayreuth, Germany
Illumination of azobenzene-containing materials with a light intensity grating does not only give rise to a refractive-index modulation in the bulk but, depending on the type of material and the polarization state of the light, also to the formation of a surface relief grating (SRG). SRGs feature high diffraction efficiencies and are, therefore, promising candidates for technical applications such as diffractive optical elements (DOEs). We demonstrate that holographic illumination with two coherent expanded laser beams (λ = 489 nm) can efficiently produce SRGs with grating constant of 1 micrometer and diameter of more than 1 centimeter on thin films of an azobenzene-containing molecular glass. Due to the non-contact holographic generation, the gratings are virtually defect-free over the whole area. AFM measurements on various spots of the grating demonstrate that for short writing times, the amplitude follows the Gaussian cross section of the writing laser, whereas a more homogeneous amplitude distribution can be achieved with longer inscription. With laser powers of a few hundred milliwatts, typical writing times are on the order of several minutes. Repeated illumination under different rotation angles of the film gives rise to complex two-dimensional SRGs.