Scientists Find That Blocking Microscopic Holes Enhances Light Transmission

Light can behave pretty weirdly. What with being indecisive as to whether it wants to be a particle or a wave, you can expect that it’ll surprise you sometimes. Not to mention that when you get down to really small scales, the laws of physics as we understand them on the macro scale don’t seem to apply. That being that case, a completely intuitive discovery by Princeton engineers isn’t completely surprising in its weirdness. What did they find? Well, they discovered that on a scale of nanometers, blocking holes with gold caps doesn’t block light transmission like you’d expect. It can actually increase light transmission by up to 70%.

This isn’t some kind of weird-but-established optical effect that anyone knew about either. “The common wisdom in optics is that if you have a metal film with very small holes and you plug the holes with metal, the light transmission is blocked completely,” said Stephen Chou, professor of engineering and head of the experiment. “We were very surprised.”

In the experiment where this was discovered, the researchers were shooting lasers through a film riddled with 60 nanometers in diameter and placed 200 nanometers apart. When they placed gold caps over the holes, caps that were 40nm thick and 40% larger than the holes themselves, they expected complete blockage. They got a 70% increase in transmission.

It’s not completely clear why this happens, but Chou says that the metal caps are actually acting as a sort of antenna and radiating the light they were intended to block. Waves will travel along the surface where there aren’t holes and then actually be broadcast by the caps, increasing the overall transmission rated. Crazy, right?

This discovery could be a big help to all kinds of endeavors in the nano-world. For researchers who don’t want light, it’s helpful to know that this is not the way to block light, and for researchers who do, it’s good to know that this can help boost transmission rates. The hope is that this discovery can aid in the improvement of microscopes, telescopes, and all manner of extremely sensitive optic equipment. It just goes to show you how complex and weird the world really is. If we’ve only just discovered that the way we block light in the macroscopic world has the opposite effect in the microscopic world, who knows what else we’re missing. Not to mention it’s just crazy that this is apparently how the world works.

(via PhysOrg)

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Eric Limer