Slashdot Mirror
Metamaterial Forms Near-Perfect Mirror
New submitter JMarshall writes: Researchers have made near-perfect reflectors out of a silicon metamaterial. These reflectors could offer a simpler, less expensive way to make high-performance mirrors for lasers or telescopes. Metamaterials typically use nanoscale patterning to create unusual properties not present in the bulk material. In this new method, researchers used off-the-shelf, nanosized polystyrene beads and allowed them to self-assemble into a monolayer with a hexagonal pattern. Using the monolayer as a photolithographic mask, the researchers etched an array of silicon cylinders, each a few hundred nanometers across, onto a wafer. The cylinders act like tiny resonators for a particular light frequency—analogous to the way a given sound frequency will make a tuning fork hum. The array reflected 99.7 % of incident light at their peak wavelength. These simple metamaterial mirrors might one day replace current high-performance reflectors, which are somewhat costly to make.
Many solar cells use reflectors to focus sunlight on the cell. This could be another good application of this technology.
In terms of lasers, well, maybe - as long as the laser uses only a very tight range of wavelengths.
Yes, most do just that... In fact, I'm not sure if there is a laser resonator that isn't pretty specific to a single wave length. To make a laser, the idea is to create a way to bounce a single wavelength of light back and forth until the photons are all going the same direction at the same time and exit the resonator. It's a lot like how a klystron resonator works when generating large amounts of microwave energy.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
For many laser applications, it doesn't matter if you lose 0.001% or 0.3% (some it does though), and the bigger issue is what is the damage threshold. Projects I've worked on needed expensive high reflectivity mirrors not because they were worried about saving another percent of power, but because they wanted as much headroom as possible for slight variation in intensity or focusing that could damage the mirror, which fail pretty much instantly once you start damaging them. I don't know how well this would do compared to dielectric coatings which are simple and solid.