Fully Automated Frequency Agile Characterisation of Organic Nonlinear Optical Materials

Organic molecular materials can exhibit remarkably strong nonlinear optical (NLO) responses which are promising for photonic applications such as ultrafast electro-optic modulators and frequency converters. Most experimental work on their haracterisation and subsequent optimisation is generally limited to one or a few laser wavelengths. Yet, recent measurements on prototypical systems using our unique setup for precise and widely wavelength-tuneable incoherent second-harmonic light scattering (hyper-Rayleigh scattering, HRS) have revealed a far more complex NLO dispersion than generally assumed, implying that the almost universally applied extrapolations to the static limit (for comparison among different compounds or with theory) and to technologically relevant frequency components of the NLO response, are often off by an order of magnitude and more. Based on much more extensive wavelength dependent measurements practical yet accurate models for the NLO dispersion will be developed. To this end, we propose to lift these techniques to a new level and drastically improve the throughput of the setup, by upgrading the laser source to a fully automatically tuneable optical parametric amplifier (OPA), and integrating it with software for automatic calibration and data processing. This will allow for detailed and reliable laser-wavelength dependent NLO characterisation by hyper-Rayleigh as well as hyper-Raman scattering to be performed routinely for a wide range of systems, providing us with a solid basis for the rational design of optimised NLO materials.

Keywords:ELECTROMAGNETISM, MATERIALS RESEARCH, MOLECULAR PHYSICS

Disciplines:Condensed matter physics and nanophysics