Light sent along metal surfaces-inside a future optical computer, for instance-may undergo reduced losses if the emitter is a thin slit or hole, experiments show.
Researchers report in Physical Review Letters that the loss of energy suffered by such metal-skimming light waves can be reduced if the waves are produced at a nanoscale slit in the metal film that carries the waves.
As shown 16 years ago , holes or slits etched in a metal film can generate SPPs when illuminated by light whose wavelength is greater than the aperture size.
Current efforts are focused on developing these apertures as “Plasmon launchers,” but little research has been done so far on the losses that occur near the holes or slits, Lalanne says.
They illuminated the film from below with an infrared laser pulse, producing SPPs on the top surface, propagating outward, perpendicular to the slit direction. So the team probed the SPP absorption by firing a second, time-delayed laser at many locations on the top of the film and detected the reflected light.
In previous work, Lalanne and his collaborators had shown that subwavelength slits produce not only SPPs, but also another type of light, which they called quasicylindrical waves.