OPTICAL FIELD ENHANCEMENT WITH PLASMON RESONANT BOWTIE NANOANTENNAS
When light of wavelength λ is focused into a medium of refractive index n, the minimum spot size due to diffraction is on the order of λ/(2n). For example, at a wavelength of 405 nm, at the edge of the visible band, diffraction limits the minimum spot size to be greater than 100 nm. Near-field techniques based on the idea that light can be passed through a tapered metal-covered optical fiber, which acts as a cut-off waveguidewhen the guide diameter is less than λ/(2n), have made it possible to obtain spot sizes on the order of 50 nm with power transmission on the order of 10−3 to 10−6 of the incident power. Similarly, passing light through a small pinhole on the order of 50 nm diameter leads to a field intensity at the end of the guide which is greatly reduced from that of the incident field.
KeywordsFull Width Half Maximum Resonant Wavelength Intensity Enhancement Bowtie Antenna Minimum Spot Size
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