Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 30: Poster: Photonics, laser development and applications, ultrashort laser pulses, quantum effects

Q 30.33: Poster

Dienstag, 18. März 2014, 16:30–18:30, Spree-Palais

Analyzing Periodically Poled Crystals by Čerenkov-Type Second-Harmonic Generation Microscopy and Spectroscopy — •Julia Hanisch, Jörg Imbrock, and Cornelia Denz — Institut für Angewandte Physik, Westfälische Wilhelms-Universität Münster

Nonlinear photonic crystals (NPC) like periodically poled lithium niobate possess a modulated χ2 nonlinearity in form of alternating ferroelectric domains. This modulation gives rise to new phase matching conditions which can be used for quasi phase-matched second-harmonic generation (SHG). We will present nonlinear optical techniques based on the so called Čerenkov-type SHG (ČSHG) to visualize ferroelectric domains in three dimensions and to determine the degree of disorder in NPCs. Efficient ČSHG occurs if the longitudinal phase mismatch is zero and the transverse phase mismatch is compensated for by reciprocal grating vectors of the NPC. In ČSHG spectroscopy the spectrum of reciprocal grating vectors is measured by SH detection. in the far field. Thus, we can determine the shape and mean diameter of ferroelectric domains in periodic and random NPCs [1]. ČSHG light is also emitted in form of two SHG spots at the Čerenkov angle when a focused fundamental laser beam hits a domain boundary. This effect is used in a ČSHG laser scanning microscope to record domain images [2].
[1]*M. Ayoub, Ph. Roedig, K. Koynov, J. Imbrock, and C. Denz, Opt. Express 21, 8220 (2013)
[2]*Y. Sheng, A. Best, H.-J. Butt, W. Krolikowski, A. Arie, and K. Koynov, Opt. Express 18, 16539 (2010)

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