Project Details
Projekt
Photorefractive Phase-Conjugating Mirror for Guiding of Light through Sub-Wavelength Metal Holes
Applicant
Professor Dr. Karsten Buse
Subject Area
Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
Term
from 2007 to 2011
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 5471245
The goal of this project is to use holographic phase conjugation in photorefractive lithium niobate crystals in order to focus and confine light to dimensions at least as small as reached by conventional optics, such as microscope objectives: A spherical wave emerging from a nanohole in a metal film on top of a lithium niobate crystal interferes with a reference wave in this photorefractive material. As a result light-induced currents generate a space charge field and, by the electrooptic effect, a refractive index pattern is recorded. This serves as the phase conjugating hologram: By phase-conjugate read-out the light should be sent back through the nano-hole, hopefully with high efficiency. Such confinement is very promising for enhanced light-matter interaction.Apertures in metal films smaller than the wavelength of light may show anomalously high transmission that is a subject of broad interest, Within the last decade, a variety of nanohole shapes and arrays have been investigated by a growing community, yet we still remain without a satisfactory explanation of the phenomenon. Furthermore, experiment, simulation, and theory have not been combined, yet. Addressing such holes by phase conjugation provides new insights.Optical near-fields play evidently a key role close to sub-wavelength apertures. By the holographic approach outlined above also all near-fields will be holographic ally recorded and retrieved. Photorefractive crystals, such as lithium niobate, offer a sufficiently high spatial resolution. Parameters such as the metal film thickness and the hole diameter as well as the illumination conditions (intensity, polarization, wavelength) will be varied in our experiments. Experimental results will be compared with predictions from a novel theory and from customized numerical simulations considering wave-guiding phenomena in sub-wavelength metal holes.
DFG Programme
Research Units
