Third order nonlinear optical response of TTF-based molecular corners

Comparative study of the nonlinear optical response of pyrrolo- tetrathiafulvalene polygons has been carried out. These materials are of great importance for photonics, because they can be used as building blocks for more complicated molecular systems like rotaxanes, catenanes which are promising candidates for opto-electronic applications like optical computing, optical switching etc. During this work the third order nonlinear susceptibility (X ⁽³⁾) has been determined by the Degenerate Four Wave Mixing experiment, while the imaginary part of the X ⁽³⁾, which is related with the nonlinear absorption was determined by "open-aperture" Z-scan measurements. Moreover measurements have been carried out in order to provide information about the optical limiting efficiency of the materials. High X ⁽³⁾ has been found reaching 2.30 × 10 ^-21 m ²/V ², corresponding to second order hyperpolarizability γ values of about 6.5 × 10 ^-45 m ⁵/V ².