Study of the interaction between light and nanoantennas in Tip-Enhanced Raman Spectroscopy

The interaction of light with nanometric metallic structures - nanoantennas - is of particular interest for material analysis techniques such as Tip Enhanced Near-Field Optical Microscopy (TENOM) and, specifically, Tip Enhanced Raman Spectroscopy (TERS). In these scenarios, the nanoantenna's response to an excitation provided by a tightly focused laser beam is essential in order to qualify the system's lateral resolution and signal-to-noise ratio. This work proposes an apparatus that enables the study of the nanoantenna's response in the focal region of light provided by a high numerical aperture optical system. The apparatus is validated by measuring the Raman scattering intensity distribution around the focal region under different conditions, enabling the precise characterization of the electromagnetic field distribution around the focal region, providing informations regarding alignment tolerance, optical signal enhancement and optical system's Point Spread Function (PSF).