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Q: Quantenoptik
Q 302: Poster: Nichlineare Optik
Q 302.9: Poster
Mittwoch, 6. März 2002, 11:00–13:00, Schloss
Spatially Resolved Second Harmonic Generation in Phases of Bent-Shaped Molecules — •Omar Morales-Saavedra1, Muhammer Bulat1, Hans-Joachim Eichler1, Sebastian Rauch2, and Gerd Heppke2 — 1Optisches Institut, TU Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany — 2I.-N.-Stranski Institut, TU Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
New banana-shaped liquid crystalline molecules have been studied as active media for SHG in their different thermophases. High effective nonlinear coefficients have been observed in the SmC-like B2-phases in case of comparatively weak applied external electric fields (4V/µ). Beside the switchable, antiferroelectric B2-phase, the so-called blue-B4-phase exhibits SHG and polar order without application of any external field.
In order to characterize the domain and crystal structure in this phase and investigate the origins of the observed spontaneous SH-activity, we developed a scanning SHG-microscope to perform spatially resolved SHG-measurements. SHG-pictures of the domains were scanned for different banana-shaped molecules in the blue-phases. Circular -right and -left polarized light was used to investigate the relation between domains with positive and negative chirality and the SH-activity.
The high nonlinear coefficients and optical switching in the different phases, make this organic materials very interesting for the development of new nonlinear optical devices. support of the VW-Foundation is acknowledged