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Science Technology

A 'salty' source of coherent light 26

Posted by Hemos
from the new-ways-of-doing-things dept.
Roland Piquepaille writes "Coherent light is produced by a beam of photons that all have the same frequency and are all at the same phase. And today lasers are the only form of technology that we know able to create such light. But by sending shock waves inside a humble crystalline material -- kitchen salt -- researchers from Lawrence Livermore National Laboratory (LLNL) have found a new way to produce coherent light for the first time in 50 years -- at least in the terahertz frequency range. This could lead to applications in optical communications, quantum computing or shock diagnostics. Read more for additional details and references about this discovery."
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A 'salty' source of coherent light

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  • Now.... (Score:2, Funny)

    by Randolpho (628485)
    ...if only they could find a way to attach this to a shark's head.
  • Quantum mechanics shows that all objects are waves and therefore may be > coherent [wikipedia.org]. Quantum coherence is usually not an event which can be macroscopicly be sensed.
  • Aha! (Score:3, Insightful)

    by Z0mb1eman (629653) on Monday January 16, 2006 @09:46AM (#14481619) Homepage
    We're finally about to discover how to extract sunlight out of cucumbers!

    The missing step was pickles!
  • Photon Shockwave (Score:2, Interesting)

    by Merlyn_3k (943281)
    So FTFA they have determined through mathematical modeling (verified by experiments with NaCl) that a piezoelectric crystal can create coherent light from the uniform motion of the atoms when the crystal is deformed by a shockwave.

    Makes me wonder if sonic stimulation at the resonant frequency could be an effective low-power LASER equivalent.
    • Re:Photon Shockwave (Score:2, Interesting)

      by hhawk (26580)
      If it did, would that mean you could use kenetic energy (gun powder, etc.) to trigger a LASER pulse? Meaning you could create a weapon that didn't need a big electrical plug?
    • by didit (820432)
      Actually, I did nor see any experiment in this paper. It only consists in modelling.
      Concerning sonic stimulation, I'm not sure it could work, but I suppose it would be even less intense. My main concern is about lifetime. How many shockwaves can a crystal support? Remember that defects in the crystal structure are going to destroy the coherence of the emitted light.
      • Sorry, misread TFA (experimental SIMULATIONS)

        Resonant stimulation would likely produce a continual low-intensity beam of coherent light (although these are actually microwave frequencies, not visible light)

        Defects in crystal structure should not affect coherence until structural collapse of the crystal, because the coherent photons are only emitted from the small area just behind the shockwave, within approx 50nm (according to the graph from the simulation) which is approx 5 orders of magnitude smaller than
    • Makes me wonder if sonic stimulation at the resonant frequency could be an effective low-power LASER equivalent.

      Shock waves are not sonic.

      • Re:Photon Shockwave (Score:2, Interesting)

        by Merlyn_3k (943281)
        A shockwave is not a sound wave, true.

        But a shockwave is a sharp pressure differential, on the order of a sawtooth wave, which in a stationary object would almost have to be created by an explosion. The shockwave propagates through a medium at the same velocity as more conventional compression waves (sound)

        A high amplitude sawtooth (or as near as practical) sound wave at the resonant frequency of the medium may be able to mimic the high pressure differential and synchronized atomic motion of a shockwave.

        Of
        • The shockwave propagates through a medium at the same velocity as more conventional compression waves (sound)

          No.. By definition shock waves travel faster than the speed of sound in the medium. Eventually enough of the energy of the shock dissipates as heat and the wave drops to sonic speeds, at which point it is no longer considered a shock wave.

          Could some kind of supersonic resonance be set up in a piezoelectric crystal? Maybe, although I can't see how it would be done, but in any case I would not des

    • "Makes me wonder if sonic stimulation at the resonant frequency could be an effective low-power LASER equivalent."

      Well, I could route it through one of the EPS taps, but it may cause the intertial dampners to destabilize. Damn I wish we had seatbelts.
  • What about those newfangled Semiconductor laser devices [google.com] that were all the rage a few years back? Or are they still considered a plain old lasers?
    • They are. Moreover, I think the press-release aspect of this report is a little overexcited. We already know you can produce coherent light by any number of stimulating mechanisms, from flashlamps to microwaves to electricity. What's new here seems only to be that a physical shock can also be the "stimulation" in the acronym ("LASER = "Light Amplification by Stimulated Emission of Radiation"). Now, given that we already knew that a physical shock can stimulate incoherent light emission -- hence the phen
  • by Wilson_6500 (896824) on Monday January 16, 2006 @09:02PM (#14487463)
    I always thought that the THz band of the spectrum was a difficult place to find _any_ sort of sources, so isn't a tunable, non-lasing THz emittier a very significant discovery in and of itself, to say nothing of another source of coherent light?
  • I remember Reading previously that scientists were trying to develop a cheap and reliable means of producing Terahertz electromagnetic waves, as they were very useful for imaging, particularly medical. Apparently they have similar properties to x-rays without that pesky ionizing radiation problem.

    Read More Here [physicsweb.org]
  • I tried to take it seriously, but the only thing I can think of while reading this is this [theonion.com] article.

In seeking the unattainable, simplicity only gets in the way. -- Epigrams in Programming, ACM SIGPLAN Sept. 1982

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