A laser shines by producing a cascade of photons that bounce around inside a light-amplifying material before exiting from one or both ends. In 2010, Douglas Stone at Yale University and colleagues devised a way to reverse the process, with a material that absorbs rather than amplifies light.
The researchers calculated that if they used a light-absorbing material like silicon, then at certain wavelengths, two identical laser beams shone directly at each other would cancel out inside the material.
Now, a team led by Hui Cao of Yale has done just that using a 110-micrometre-wide slab of silicon.
The researchers chose the wavelength of the laser light so that light waves hitting the outside of the slab from the laser beams were in just the right phase with the waves transmitted through the material to trap the light inside the slab.
The silicon absorbed 99.4 per cent of near-infrared light with a wavelength of 998.5 nanometres, turning it into heat. "Theory and experiment matched very well," says Stone. "We couldn't have expected to do any better."
Read more at New Scientist
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