A 'salty' source of coherent light

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."

Quantum mechanics shows that all objects are waves

[Device666]

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.

Photon Shockwave

[Merlyn_3k]

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

[hhawk]

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?

Re:Aha!

[j_cavera]

You may think that funny, but... If you take a humble kosher dill and stick a nail into either end, then run normal 110v AC through said pickle, it will glow with a soft yellow light as the salt in the brine becomes excited. Go ahead an try this at home. For some reason, kosher dills do this best. So given this as prior art, I'd take the laser findings with a grain of ... yeah, whatever. - Jim

Re:Photon Shockwave

[Merlyn_3k]

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 course, these are after all piezo crystals we are talking about here, so perhaps a properly timed voltage differential could be applied to generate the same effect.

deconstructing the acronym...

[Quadraginta]

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 phenomenon of triboluminescence, otherwise known as the crunching wintergreen LifeSavers makes sparks effect -- it doesn't seem real surprising that physical shock can stimulate coherent light emission under the right circumstances.

I can believe the simulations establish the possibility of shock-stimulated coherent light emission, but I am very doubty of the amplitude. There's no way they could do the simulation in as much detail and long enough to account for all the side-channels and decay mechanisms in a real crystal. There's a lot of experimental work ahead before this proves to be a solid discovery. But it's a neat little story, nonetheless.

Correct me if I'm wrong...

[Wilson_6500]

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?