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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.

79 comments

  1. Skittles by holmstar · · Score: 4, Funny

    Now they need to implement this in candy form, so you can taste the rainbow.

    1. Re:Skittles by Anonymous Coward · · Score: 0, Funny

      You know, even if you had your hands up, I'd shoot you...

  2. woa.. by Charliemopps · · Score: 3, Funny

    How many did they trap at once? Was it a double? Triple rainbow?!?!

    1. Re:woa.. by DigiShaman · · Score: 1

      What's it mean....??!!

      --
      Life is not for the lazy.
    2. Re:woa.. by Anonymous Coward · · Score: 0

      [bold][caps]A Quadruple Rainbow!!!![/caps][/bold]

      /me headsplosion

    3. Re:woa.. by Anonymous Coward · · Score: 0

      It's like a triple salchow. No one is quite sure what it is or how to spell it, except the figure skaters themselves, but it sounds flashy and impressive and wins lots of awards. Plus, we get to watch half naked figure skaters (entertainment for both sexes/genders, mind you!).

  3. At last! by ArcadeMan · · Score: 5, Funny

    If they're able to trap rainbows, surely they're also able to trap that damn Leprechaun.

    1. Re:At last! by Anonymous Coward · · Score: 0

      Lucky Charms for everybody!

    2. Re:At last! by Overzeetop · · Score: 1

      The Irish equivalent of rocky mountain oysters?

      --
      Is it just my observation, or are there way too many stupid people in the world?
    3. Re:At last! by Jason+Levine · · Score: 5, Funny

      Finally, step 2 is revealed!

      Step 1: Trap a rainbow.
      Step 2: Seize the pot of gold at the end of the rainbow.
      Step 3: Profit!

      --
      My sci-fi novel, Ghost Thief, is now available from Amazon.com.
    4. Re:At last! by Anonymous Coward · · Score: 0

      poor wee bugger wouldna know if he was coming or going.

    5. Re:At last! by Anonymous Coward · · Score: 0

      You, sir, win the Internets for being the first person to put in a Step 2 and not make me want to throttle them.

  4. CAN I TRAP LIGHT AND HAVE AN INFINITE LIGHTBULB? by Anonymous Coward · · Score: 0, Redundant


     

  5. I'll save my tears by Anonymous Coward · · Score: 0

    For the day they trap a double rainbow.

    1. Re:I'll save my tears by Cederic · · Score: 1

      Technically they've trapped an infinite rainbow. It repeats itself until released.

      Although, introducing the word 'infinite' raises the question of energy. How much energy does the rainbow lose while trapped?

  6. DON'T! by Anonymous Coward · · Score: 0

    D0N'T TRAP GOD'S BEAUTlFUL CREATION! THIS lS A REMINDER THAT HE W0N'T FL00D US AGAIN!

    1. Re:DON'T! by fuzzyfuzzyfungus · · Score: 2

      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?

    2. Re:DON'T! by Culture20 · · Score: 1

      Why are you using 0 instead of o/O?

      I'm guessing it allows one to bypass the lameness filter. 1T'5 APPARENTLY N0T L1KE YELL1N6 since it's not all caps.

    3. Re:DON'T! by Anonymous Coward · · Score: 0

      Why are you using 0 instead of o/O?

      I'm guessing it allows one to bypass the lameness filter. 1T'5 APPARENTLY N0T L1KE YELL1N6 since it's not all caps.

      Indeed it does. I wouldn't be a good angry Christian complaining about science IF I WEREN'T USING ALL CAPS!

      I also dropped some the uppercase "i"s to lowercase "L"s. Just had to beat that threshold.

  7. what? no graphene? by shadowrat · · Score: 3, Funny

    how is this even possible without graphene, carbon nanotubes or metamaterials? This is just done with normal everyday stuff?

    1. Re:what? no graphene? by Cenan · · Score: 1

      They didn't even 3D print anything. I call bullshit on this whole thing.

      --
      ... whatever ...
    2. Re:what? no graphene? by Anonymous Coward · · Score: 0

      Technically those are made out of everyday stuff. For example, Carbon is literally everywhere

    3. Re:what? no graphene? by tkotz · · Score: 1

      Don't panic, After RTFA, some meta materials were involved in getting the negative Goos-Hachen effect.

    4. Re:what? no graphene? by tkotz · · Score: 1

      Nevermind the meta-materials were the old way to do this. This is just a hunk of silicon and silica. We could probably fab this with a standard lithographic technique pretty easily by finding a way to mask the bonding of oxygen with a silicon slab.

    5. Re:what? no graphene? by sexconker · · Score: 2

      Carbon is literally not everywhere.

    6. Re:what? no graphene? by shadowrat · · Score: 1

      It's like the hipsters came along and said, "i'm not using the meta materials modern society is pushing on me, i'm only getting craft Goos-Hachen effect made the way my grandpa would make it. with dirt!"

    7. Re:what? no graphene? by wiredlogic · · Score: 1

      Or use an Arduino. Toooootally fake.

      --
      I am becoming gerund, destroyer of verbs.
    8. Re:what? no graphene? by grcumb · · Score: 1

      Or use an Arduino. Toooootally fake.

      Mos def. I mean, look at the shadows along the edges, and the borders between the colours. Moiré patterns all over the place! I use Photoshop professionally, and I'm telling you, it's photoshopped.

      --
      Crumb's Corollary: Never bring a knife to a bun fight.
  8. Mind-blowingly cool, but... I don't get it. by pla · · Score: 2

    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.

    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
    // Serious question, though... Thanks!

    1. Re:Mind-blowingly cool, but... I don't get it. by Overzeetop · · Score: 1

      The implication, also, is that you can't actually see the rainbow I would presume, since no light is getting out.

      --
      Is it just my observation, or are there way too many stupid people in the world?
    2. Re:Mind-blowingly cool, but... I don't get it. by Anonymous Coward · · Score: 5, Informative

      It's a wave guide. Light travels along it, but because of the diffraction grating on the top, light gets shifted backwards as it bounces off the top. The trick is different frequencies get shifted back by different amounts, so they change the spacing of the grating over the length of the device, so that first one color gets stalled, while the rest move on and then the next stalls, until they're all stopped. However, they aren't trapped forever, the waveguide has "ohmic loses", which means light is absorbed by guide and so it eventually is lost.

    3. Re:Mind-blowingly cool, but... I don't get it. by Mr+Z · · Score: 1

      Due to self-interference, the light bumps into itself on the way out, and subsequently can't get out. At least at my limited level of understanding, it's the wave-light nature of light at play here.

      I imagine at some point, the trapped photons all get absorbed and the original energy dissipates as heat.

    4. Re:Mind-blowingly cool, but... I don't get it. by sexconker · · Score: 1

      Imagine a car that runs into a wall and bounces off at angle X, then hits another wall and bounces off at angle Y, and ends up in a ditch.

      This is like the wall shifting your car back x feet at the moment of impact so that when it bounces off at angle X and hits the second wall, it does so at a spot directly across from the original impact on the first wall. The second wall will also shift the car back, so when it bounces off it at angle Y, instead of ending up in the ditch it ends up impacting the same spot on the first wall. If you can do this such that angle X and Y are equal (respective to the incident walls), then the car will bounce back and forth between the two walls forever (until stopped by friction/gravity/whatever). Alternatively, the angles can be different but the points of contact not lined up - you'd have 4 (or more) points of contact in an X or hourglass configuration.

    5. Re:Mind-blowingly cool, but... I don't get it. by dinfinity · · Score: 1

      I believe GP was specifically referring to the 'stopped' part. Considering we've always learnt that the speed of light (photons) is more or less static(ally high), it's pretty hard to accept photons just being slowed down to a halt.

      IANAP, but I've learnt from Feynman's QED lectures that reflection is not as straightforward as one tends to think it is. IIRC, reflection is more of an absorption + emission-event than a 'bouncing' event. Combining that with the text "Removing the silicon grating from the silica waveguide releases the light again" would lead me to think that the grating allows the absorption of the photon(s) to happen, but leaves the absorbing material in a state in which it is unable to complete the emission event and in such a way that the emission event is put 'on hold'. The latter would be that the energy is unable to dissipate in other ways.

      Again, IANAP, and I'm pretty much pulling this out of my ass, but this is how I wrap my head around it.

    6. Re:Mind-blowingly cool, but... I don't get it. by Anonymous Coward · · Score: 0

      Well i got it, so great ass pulling :D

  9. I can't stand the phrase "so-called"! by hamster_nz · · Score: 2

    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!

    1. Re: I can't stand the phrase "so-called"! by Anonymous Coward · · Score: 0

      You mean "so-called" opposite meanings.

    2. Re:I can't stand the phrase "so-called"! by wonkey_monkey · · Score: 1

      You
      Are
      Not
      Alone

      --
      systemd is Roko's Basilisk.
    3. Re:I can't stand the phrase "so-called"! by RabidReindeer · · Score: 1

      It has two completely opposite meanings:

      Yeah, yeah.

    4. Re:I can't stand the phrase "so-called"! by Livius · · Score: 3, Informative

      It means an identifier that is not the actual name or not an actual literal description. Nothing is implied about accuracy.

  10. what? no graphene? by Anonymous Coward · · Score: 0

    Sensing a troll. You must be a troll.

  11. They have created slow glass! by Anonymous Coward · · Score: 0

    I want a few panes that have been hanging around Crater Lake.

    1. Re:They have created slow glass! by mcswell · · Score: 1

      In case someone doesn't catch the reference: http://en.wikipedia.org/wiki/L....

  12. In the future... by Mr+Z · · Score: 1

    In the future, instead of complaining about letting the blue smoke out, we'll complain about letting the blue light out.

    1. Re:In the future... by Nethemas+the+Great · · Score: 1

      I thought we already complained about the blue screen of death...

      --
      Two of my imaginary friends reproduced once ... with negative results.
    2. Re:In the future... by JasonGoatcher · · Score: 1

      I still wish I could send the blue light back into blue headlights.

  13. DON'T! by Anonymous Coward · · Score: 0

    Why are you using 0 instead of o/O?

  14. Accidentally double rainbow? by TangoMargarine · · Score: 1

    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 back towards the source rather than away from it.

    Don't the editors even read the freaking summary through once?! I don't know about you, but the most glaring error I usually notice is when I accidentally the sentence through and there's no verb.

    (and I thought starting a sentence with a numeral was also one of those things you're not supposed to do)

    --
    Unity? Screw that: XFCE. Slashdot Beta? Screw that: SoylentNews. Australis? Screw that: Pale Moon. UX developers DIAF
    1. Re:Accidentally double rainbow? by Anonymous Coward · · Score: 0

      Come on baby, back that rainbow up.

    2. Re:Accidentally double rainbow? by wonkey_monkey · · Score: 1

      back v. walk or drive backwards

      Also "discovered" and "be" are there, if I was being pedantic about "no verb."

      --
      systemd is Roko's Basilisk.
    3. Re:Accidentally double rainbow? by TangoMargarine · · Score: 1

      I don't think you can really apply the verb "back up" to light. Light is a ray that propagates without any sense of volition. Walking and driving both imply a conscious decision and effort on the part of the thing doing the walking or driving.

      "No verb in this clause," if you like.

      --
      Unity? Screw that: XFCE. Slashdot Beta? Screw that: SoylentNews. Australis? Screw that: Pale Moon. UX developers DIAF
  15. Fake Story. Lookat domain name by Anonymous Coward · · Score: 0

    You too funny

  16. How much light? by shaitand · · Score: 1

    Are we seeing the forerunner to light based batteries? You wouldn't actually need to trap light for memory in an optical system, you only need to have light leave at least a temporary imprint that will impact light bounced against it later.

    1. Re:How much light? by Anonymous Coward · · Score: 0

      Take it a step further. Slightly tilted and automatic shifting sections to generate any pattern/picture we want. Well, we probably couldn't shift the sections fast enough. Maybe they'd be prefabricated and you'll have a light based photo. Shine a flashlight in and get an full color image on the other end. Wait, we already have those...

    2. Re:How much light? by shaitand · · Score: 1

      A step further? A light based battery is a step enough for me. Light has no mass.

    3. Re:How much light? by swb · · Score: 1

      Solar batteries. You don't convert those photons into electricity and store that, you just store the light and then you can shine it on the solar cells when you need the power.

      I'm absolutely sure it doesn't work like this but it's an interesting science fiction concept.

    4. Re: How much light? by GigaplexNZ · · Score: 1

      So what if light has negligible mass? The battery will still be heavy.

    5. Re: How much light? by shaitand · · Score: 1

      Not necessarily as I understand it. Electrical energy currently has to be stored as a potential within a chemical element. They aren't heavy because of the electrons they are heavy because a higher capacity battery literally means a bigger battery filled with a larger quantity of heavy chemicals.

      This is more like a capacitor, actually trapping photons without a chemical storage and then releasing all of them in a burst. But unlike a capacitor the potential isn't between differently charged photons fighting each other. The "potential" is in the momentum of the photon which is retained and not in the force used to store it. The photon is being held in a balanced stasis, retaining it's momentum, and not being resisted by an insulator that will ultimately fail. Even better, they can selectively trap different frequencies of light.

      That is super nice in terms of potential. Imagine your home in a world where these are built with large capacity. Your solar panel is no longer an inefficient convertor of light energy into electrical potential. It is now a light collector, it carries the light via an optical cable to a large capacity light battery that selectively traps visible and infrared light and lets excess pass out of your home. You don't block UV, you just let it pass away, so you aren't constantly eroding a blocking solution. The IR light is trapped as well but because it is held in stasis it's energy is retained and the battery holding it isn't hot and doesn't need insulated. This is used to heat your water and home. If your collector was on the roof the collecting of this IR light also goes a very long way toward keeping your home cool. The light in your home is the full visible spectrum of the sun (or any blend of any part of it you like) and even at night is actually sunlight. Not converted to electricity at 40% efficiency and back to light at 95% efficiency. The high capacity light batteries might need to be built in banks with smaller capacity, allowing you to release the amount of light you need in to the fine units of X, you can release 1X/s for 50s or you can release 50X/s for 1s.

      None of that even requires optical computing. But with fully optical computing your gadgets will eventually all run directly on light. So again, no need for systems that convert other forms of energy to electricity with maybe 40% efficiency. You still have losses of course, imperfection in your optical fiber for instance. But the biggest loses come from that conversion and you've just taken our biggest forms of consumption (light/heat) and eliminated the need for conversion. The next biggest is mechanical energy. That does require conversion, but light is actually an excellent candidate for highly efficient conversion to mechanical energy, there is an awful lot of momentum there.

      It's also CO2 and heat neutral, actually there should be a net reduction in global warming because some amount of energy from the sun that would have been released as heat will always be contained in the cumulative balance of these storage systems that never existed before.

    6. Re:How much light? by shaitand · · Score: 1

      If you are using the output to light your home, transmit data, or heat up some stew you don't need the solar cells. Toss light based computing in and you don't even need electronics anymore. I should be possible to create a reasonably efficient light motor as well, light can give up it's momentum and it has lots of it. If we can create a solar sail based on this we can create a motor. Light will bend in a magnetic field, that suggests and interaction that transfers energy, it would seem like it should be possible to build that interaction into a motor if you had enough light energy.

    7. Re: How much light? by GigaplexNZ · · Score: 1

      Not necessarily as I understand it. Electrical energy currently has to be stored as a potential within a chemical element. They aren't heavy because of the electrons they are heavy because a higher capacity battery literally means a bigger battery filled with a larger quantity of heavy chemicals.

      That's not the only way to store electricity, it's just the least leak prone method we currently have. It's also partially my point - just because light has negligible mass doesn't make the battery light either.

      It's interesting that your lightweight optical battery description happens to be for a house (immobile) and ignores the conversion between electricity, treating that as a separate piece of hardware. Completely useless for a mobile device, which is where you actually care about the mass of the battery.

    8. Re: How much light? by shaitand · · Score: 1

      "That's not the only way to store electricity, it's just the least leak prone method we currently have."

      Right, which makes it the way the we have to do it. ;)

      "It's interesting that your lightweight optical battery description happens to be for a house (immobile) and ignores the conversion between electricity, treating that as a separate piece of hardware"

      It's interesting that you assume a conversion between electricity when I clearly outlined a scenario in which none is required. What are you going to do convert light gathered from the massive fusion reactors that fill our sky into electricity and feed it into a light bulb to turn it back into light? Of course not, you are just going to route it with fiber optic cabling and shine it through a diffuser directly down into your living room. The same with heat, you capture IR and shine that into your home. No electricity needed.

      "It's interesting that your lightweight optical battery description happens to be for a house (immobile) and ignores the conversion between electricity, treating that as a separate piece of hardware. Completely useless for a mobile device, which is where you actually care about the mass of the battery."

      The scenario was of the most useful application not depending on advances in optical computing. A battery that doesn't break down with recharge/discharge cycles and can have an incredible capacity without extreme mass is important in a home setting where you'd want to store the 3000w per square meter the sun is shining down on your roof. Also potentially in a vehicle. With existing electronics the lightweight battery would need to be converted to electricity and that would add an extra component that might not make it the answer in all cases. Of course it would still be carbon neutral and require very small pieces of our most efficient solar conversion panels, made more efficient by the fact we could pick the exact spectrum of light we will use, tune the panels to that spectrum, and we can make nearly perfect mirrors when turning for a specific frequency of light and release into a chamber lined with that.

      With advances in optical computing your mobile device doesn't use electricity, it runs on light, recharges anywhere it is light out, and/or from an optic cable coming out of the wall and no conversion is required. Of course, NONE of that works, house, car, mobile devices, without an optic battery. Many of those applications work just fine without optical computing or memory.

  17. Re:CAN I TRAP LIGHT AND HAVE AN INFINITE LIGHTBULB by neoritter · · Score: 1

    You wouldn't be able to illuminate anything if the light never goes anywhere?

  18. Clicked on FTA by Anonymous Coward · · Score: 0

    Looked for a picture of a trapped rainbow, left disappointed.

  19. not an experimental demonstration by henryteighth · · Score: 5, Informative

    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?

    1. Re:not an experimental demonstration by iggymanz · · Score: 1

      and I RTFP curious to how long the pulse could really be "frozen", no joy there

  20. Trapped light by pellik · · Score: 1

    I'm not clear on this, does all the trapped light get released at once when you open the gate? Like shine a flashlight at the thing for 6 months and create a blinding flash?

  21. How Sad by hughbar · · Score: 1

    A trapped rainbow, how sad. Next thing they'll be freezing the nice pink unicorns. This is bad science and something must be done, just think of the children.

    --
    On y va, qui mal y pense!
  22. Light of Other Days by shutdown+-p+now · · Score: 2

    If I understand the described effect correctly, they have made something very much like "slow glass" from Shaw's "Light of Other Days".

    1. Re:Light of Other Days by Anonymous Coward · · Score: 0

      Thank you, I have been trying to figure out what story had slow glass for at least 15 years. I was in a SF bookstore and asked for Slow Glass, and the casher said "Snow Crash?"

    2. Re:Light of Other Days by sysrammer · · Score: 1

      I thought of this too, but couldn't remember who wrote it. I remember reading one of the series he did on slow glass waybackwhen. It definitely caught my imagination then. Good stuff.

      --
      His ignorance covered the whole earth like a blanket, and there was hardly a hole in it anywhere. - Mark Twain
    3. Re:Light of Other Days by Lorens · · Score: 1

      At least they will have done it on purpose and not while researching a windshield for an airplane . . . Splat.

  23. I'm sure the Christians and the gays will be along by JasonGoatcher · · Score: 1

    shortly to put their own spin on things, since they both consider themselves represented by rainbows.

  24. Would love to understand this by Anonymous Coward · · Score: 0

    but can't even read the hipsteriffic website.

  25. Next step? by Black+Copter+Control · · Score: 1

    It seems to me that the next step would be to find a way to activate and release gratings electronicall (or, even better -- optically) , rather than physically.

    --
    OS Software is like love: The best way to make it grow is to give it away.
  26. Two more steps to true photonic processing by Mr.CRC · · Score: 1

    1. Optical switching of the grating, and 2. do this in an optical gain medium. Then you CAN keep the light trapped forever and implement optical buffers, flip-flops, etc.

  27. Re:CAN I TRAP LIGHT AND HAVE AN INFINITE LIGHTBULB by sjames · · Score: 1

    So it's like a rainbow in the dark...

  28. Re:CAN I TRAP LIGHT AND HAVE AN INFINITE LIGHTBULB by Anonymous Coward · · Score: 0

    No sign of the morning coming! You've been left on your own...

  29. Relativistic implications. by lostmagik · · Score: 0

    Does that mean that the photon experiences time? Or somehow we could experimentally test for its intrinsic mass?