Investigation into the third order nonlinear optical properties of potential harmonophores

Abstract

Third harmonic generation (THG) microscopy uses the nonlinear optical effect called harmonic generation (HG) to study materials and compounds. It is an advantageous technique for biological imaging, as unlike fluorescence microscopy, it does not risk damaging the sample through photobleaching. In this, imaging is performed by contrasting the difference in the THG signal generated by the sample. This difference can be enhanced for the sample through the use of dyes that act as strong harmonophores, which are compounds that generate strong THG signal. The ability to generate strong THG signal can be evaluated through determining the second hyperpolarizability (&gamma;) value for the compound. </span></p> <p><span>In this thesis, an investigation into the nonlinear optical properties of starting materials and a set of pyrrole compounds for a series of ruthenium-pyrrole complexes was performed using THG microscopy. The second hyperpolarizability (&gamma;) values for each compound were determined using the THG ratio technique. This work acts as a base to evaluate how to optimize the rutheniumpyrrole complexes to improve their potential for use as dyes for THG microscopy.