Thursday, November 12, 2009

Color Sorting with a Bow-Tie

A Fractal antenna is more efficient than a conventional antenna, which is why most cell phones already have them embedded. This level of compactness is highly beneficial for long wavelength radiation such as: DTV, Wi-Fi, FM and AM radio. What about shorter wavelengths, like visible light?

optical bow tie antennaResearchers at the Lawrence Berkeley National Laboratory have engineered a new class of bowtie-shaped devices that capture, filter and steer light at the nanoscale. These "nano-colorsorter" devices act as antennae to focus and sort light in tiny spaces, a potentially useful technique for harvesting broadband light for color-sensitive filters and detectors.

The scanning electron image (at left) of a nano color sorter shows the vertical bow-tie antenna shifted 5 nm to the left of center. In Figure (a) the bowtie has been exited at 820 nm and in Figure (b) at 780 nm wavelength. The two modes are spectrally and spatially distinct while maintaining nanoscale mode volumes. [Source: LBNL]