Ultrashortpuls laser system for coupling to a near-field optical microscope

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For our research in the area of nanophotonics, particularly for studies in the spectral regime of the near- and mid-infrared, we are in need of a flexible and widely tunable laser source with a time resolution of hundreds of femtoseconds. We will couple this light source to an already existing scattering-type near-field optical microscope, in order to study photonic surface waves over a wide spectral regime, from the visible to wavelengths of about 15 microns. A particular focus of this research will lie on polaritons, set up via the coupling of infrared radiation to the oscillations of phonons in nanostructured dielectric substrates. Additional areas of study are surface-enhanced molecular spectroscopies and chemical energy conversion caused by hot electrons excited in infrared-active plasmonic materials such as ZrN and TiN. Via coupling of the laser beam to the near-field optical microscope, we will be able to perform experiments with a spatial resolution of only a few nanometres. This will enable fundamental research work on the localization of infrared radiation into minute areas far below the diffraction limit, with applications in molecular spectrosocpy, imaging, and energy conversion. The preferred system offers additional possibilities such as pump/probe ultrashort pulse spectroscopy and a very high tunability range from 720 nm to 16 microns wavelength.