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First Experimental Demonstration of a Trapped Rainbow Using Silicon
KentuckyFC writes Back in 1947, a pair of physicists demonstrated that when a beam of light reflects off a surface, the point of reflection can shift forward when parts of the beam interfere with each other. 60 years later, another group of physicists discovered that this so-called Goos-Hanchen effect could sometimes be negative so the point of reflection would go back toward the source rather than away from it. They even suggested that if the negative effect could be made big enough, it could cancel out the forward movement of the light. In other words, the light would become trapped at a single location. Now, physicists have demonstrated this effect for the first time using light reflected off a sheet of silica. The trick they've employed is to place a silicon diffraction grating in contact with the silica to make the interference effect large enough to counteract the forward motion of the light. And by using several gratings with different spacings, they've trapped an entire rainbow. The light can be easily released by removing the grating. Until now, it has only been possible to trap light efficiently inside Bose Einstein Condensates at temperatures close to absolute zero. The new technique could be used as a cheap optical buffer or memory, making it an enabling technology for purely optical computing.
Now they need to implement this in candy form, so you can taste the rainbow.
How many did they trap at once? Was it a double? Triple rainbow?!?!
If they're able to trap rainbows, surely they're also able to trap that damn Leprechaun.
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how is this even possible without graphene, carbon nanotubes or metamaterials? This is just done with normal everyday stuff?
Okay, I take some pride in usually understanding at least the basics behind cool science tricks like this, but I have to admit, this one just blows me away - I still don't "get", it even after reading TFAs.
// Serious question, though... Thanks!
So can someone explain what really happens here? Does the light keep reflecting between the two surfaces, as though caught between two "perfect" mirrors? Or do the photons (and does this depend on wave behavior, or could we do it for particles as well) just basically stop mid-air, something like an event horizon as seen from the inside? Or something else entirely?
/ Bonus points for a car analogy. XD
It has two completely opposite meanings:
1: commonly named e.g. "the so–called pocket veto"
2: falsely or improperly so named e.g. "deceived by a so–called friend"
It drives me crazy!
Exactly! A perfect solution to the problems of drought and flooding: should things get a bit parched, we trap up the population of wild rainbows and the old guy (his memory must be going a bit by now, it's been an eternity after all) stops receiving his reminders and starts flooding us. Once we've had enough rain in a given spot, we just ship an appropriate number of rainbow enclosures there and re-introduce them into the wild.
Optical computing and practical weather control, what's not to like?
The paper is entirely numerical simulation, despite what the linked blog post says. I quote: "In this paper, we numerically demonstrate an approach..". I'm not denigrating numerical simulations: I'm a computational physicist. Just, you know, RTFA?
If I understand the described effect correctly, they have made something very much like "slow glass" from Shaw's "Light of Other Days".