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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 88: Responsive and Adaptive Systems

CPP 88.4: Vortrag

Donnerstag, 19. März 2020, 10:15–10:30, ZEU 114

Polarization controlled fine structure of diffraction spots from optically induced azo-polymer surface relief grating: In-situ atomic force microscopy and diffraction efficiency measurements — •Joachim Jelken, Carsten Henkel, and Svetlana Santer — Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany

Here we present an experimental and theoretical study of an observed fine structure in the diffraction spot of an azo-polymer surface relief grating. This is achieved utilizing a homemade setup [1] which consists of three parts: a two beam interference setup for topography structuring, an atomic force microscope (AFM) for in-situ recording of surface morphology, and a diffraction efficiency (DE) setup which enables to obtain information about the birefringence grating at the same time. Our findings show that the fine structure is a result of a gaussian intensity profile of the recording interference pattern [2], which will create a gaussian amplitude modulation (envelope) of the surface and birefringence grating. A wide probe beam will average across the grating which results in the observed fine structure of the diffraction spot. The spatial profile of the diffraction spot is thereby converting from a gaussian, to a *donut* (dark spot in the center) and finally to a *Saturn* (bright ring with bright center) structure with an increase in the SRG height. We will show that we can switch between the different spatial profiles by changing the polarization of the probe beam. [1]J. Jelken and S. Santer, RSC Advances, 2019, 9, 20295-20305 [2]J. Jelken, C. Henkel and S. Santer, Appl. Phys. B, 2019, 125, 218