Deep Punj is giving a talk at the 13th international conference of Near-field Optics and Nanophotonics NFO13 on nanoantennas for enhanced single molecule fluorescence detection at high concentrations. Our group will also have two posters:
- Plasmonic enhanced fluorescence energy transfer
- Enhanced fluorescence from resonant DNA assembled plasmonic nanoantennas loaded with single dye molecules
Energy transfer between molecules is promoted when they are set in an environment that confines light
The energy transfer between molecules is an essential phenomenon for photosynthesis, photovoltaics and biotechnology. Now, thanks to the work of the Institut Fresnel Institute, energy transfer between molecules can be controlled and enhanced with optical structures etched at the nanoscale.
Researchers prepared pairs of energy donor and acceptor molecules linked by rigid double stranded DNA. These pairs were then inserted into apertures milled in a gold film with nanoscale dimensions. By accurately measuring the radiation properties of pairs of molecules, the researchers were able to demonstrate that the rate of energy transfer between molecules is 6 times greater when placed in a nanoaperture.
These promising results are clearing a new path to improve the energy transfer process widely used in life sciences and biotechnology. Optical nanostructures open up many potential applications for biosensors, light sources or photovoltaics.
This work has been supported by the European Research Council under ERC Grant 278242.
The ability to design metamaterials with the prescribed properties is a key to their numerous applications and a focus of intense studies in the photonics community. As metamaterials are engineered at a scale which is much smaller than the wavelength of light, it is possible to treat them as a homogeneous medium with the effective values of permittivity and permeability. Nevertheless, there is no common approach to extract these effective parameters despite the significant efforts of the research community over the last years.
In a recent paper published in Phys Rev B, we propose a novel approach to extract the homogenized parameters by analyzing the reflection and transmission spectra. We show that this generalization preserves the physical meaning of the effective parameters at high frequencies and in the vicinity of resonances, where the nonlocal contributions cannot be neglected. It is also shown the decomposition of scattering spectra into even and odd modes helps to separate various contributions and to derive the explicit formulas for the effective permittivity and permeability which always satisfy the passivity and causality constraints.