Light waves trapped on a metal’s surface, ie surface plasmons, travel farther than expected, up to 250 microns from the source. While this distance is just 1-100th of an inch, it is far enough to possibly be useful in ultra-fast electronic circuits. Scientists captured the surface plasmons’ travel on video. Future computer circuits could use this phenomenon as interconnects.
Specially designed, extremely small metal structures can trap light. Once trapped, the light becomes a confined wave known as a surface plasmon. The plasmons can propagate almost as fast as light through the air.
Researchers at Pacific Northwest National Laboratory experimentally showcased the unique ability to study a surface plasmon.The team applied 2 laser pulses to a gold sample surface: the first is called the pump, while the second is called the probe. The pump is used to generate the surface plasmon and is followed by the probe on a time delay, which detects the surface plasmon. By continuously tuning the time delay between the pump and probe pulses, the team monitored the motion of the plasmon on the gold surface.
They captured the confined waves propagating on video, helping to directly extract details such as wavelength and speed. They also determined a propagating plasmon can be detected at least 250 microns away from the generation source, ie it can travel far enough to be useful in electronic circuits. Besides super fast computers, other devices include biological, health, and energy arenas. http://science.energy.gov/bes/highlights/2015/bes-2015-08-d/
Ultrafast Imaging of Surface Plasmons Propagating on a Gold Surface We record time-resolved nonlinear photoemission electron microscopy (tr-PEEM) images of propagating surface plasmons (PSPs) launched from a lithographically patterned rectangular trench on a flat gold surface. Our tr-PEEM scheme involves a pair of identical, spatially separated, and interferometrically locked femtosecond laser pulses. Power-dependent PEEM images provide experimental evidence for a sequential coherent nonlinear photoemission process, in which one laser source launches a PSP through a linear interaction, and the second subsequently probes the PSP via two-photon photoemission. The recorded time-resolved movies of a PSP allow us to directly measure various properties of the surface-bound wave packet, including its carrier wavelength (783 nm) and group velocity (0.95c). In addition, tr-PEEM images reveal that the launched PSP may be detected at least 250 μm away from the coupling trench structure. Credit: 10.1021/acs.nanolett.5b00803
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