Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.

 

POLARIZATION CONTRAST IN PHOTON SCANNING-TUNNELING-MICROSCOPY COMBINED WITH ATOMIC-FORCE MICROSCOPY


PROPSTRA K, VANHULST NF
JOURNAL OF MICROSCOPY-OXFORD
vol 180: p165-p173 part 2 NOV 1995

Photon scanning tunnelling microscopy combined with atomic force microscopy allows simultaneous acquisition and direct comparison of optical and topographical images, both with a lateral resolution of about 30 nm, far beyond the optical diffraction limit. The probe consists of a modified microfabricated silicon nitride tip mounted o­n a cantilever, commercially available for atomic force microscopy. The lateral resolution is further improved using 'supertips', by depositing a small needle o­n the silicon nitride tip. The combined microscopic technique is applied to thin films of indium tin oxide because of the small grain size and high surface flatness, providing high-resolution optical contrast and limited far-field scattering contribution. Polarization contrast is shown in experiments both changing the polarization of the incident and detected light. Approach curves, both measuring the optical signal and force interaction, show a difference in the optical coupling between p- and s-polarized incident light, p-Polarized light always provides optical contrast more correlated to topography than s-polarized light, both for incident and detected light, in agreement with theoretical models.
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