Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter at the nanoscale. We do this by exploring ways to shape light and its environment. It's what we call active and passive control. Our current focus is on the interaction of light with biomolecules and nanostructures. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.
We participate in the EU-COST actions MP1102: Coherent Raman microscopy (MicroCor) and CM1202: Supramolecular photocatalytic water splitting (PERSPECT-H2O)


Stimulated-emission pumping enabling sub-diffraction-limited spatial resolution in coherent anti-Stokes Raman scattering microscopy

(full pdf)

Carsten Cleff, Petra GroƟ, Carsten Fallnich, Herman L. Offerhaus, Jennifer L. Herek, Kai Kruse, Willem P. Beeker, Chris J. Lee, and Klaus-Jochen Boller
Physical Review A 87, 033830 (2013)
vol. 87, p033830, march 25, 2013

We present a theoretical investigation of stimulated emission pumping to achieve sub-diffraction-limited spatial resolution in coherent anti-Stokes Raman scattering (CARS) microscopy. A pair of control light fields is used to prepopulate the Raman state involved in the CARS process prior to the CARS signal generation. Efficient prepopulation is achieved by employing a path via an electronic or vibrational state. Thereby, the buildup of a coherence between the ground and Raman state during irradiation by the light fields for CARS signal generation is prevented, resulting in the suppression of the CARS intensity by more than 99.8%. Two-dimensional spatial excitation profiles have been calculated using donut-shaped spatial profiles for the control light fields, thus, an intensity-dependent narrowing of the CARS excitation profiles below the diffraction limit. Using computergenerated test images we demonstrate a resolution beyond the diffraction limit for CARS microscopy, which is scalable by the control light field intensity, similar to stimulated emission depletion microscopy.
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