Navy Scientists Develop Laser For Underwater Communication

Researchers at the Naval Research Laboratory claim to have come up with a better tool for underwater acoustics. The new system uses laser light to create sound underwater from a distance. This technology could allow planes a much easier method of communicating with submarines without the need for a floating buoy. "Efficient conversion of light into sound can be achieved by concentrating the light sufficiently to ionize a small amount of water, which then absorbs laser energy and superheats. The result is a small explosion of steam, which can generate a 220 decibel pulse of sound. Optical properties of water can be manipulated with very intense laser light to act like a focusing lens, allowing nonlinear self-focusing (NSF) to take place. In addition, the slightly different colors of the laser, which travel at different speeds in water due to group velocity dispersion (GVD), can be arranged so that the pulse also compresses in time as it travels through water, further concentrating the light. By using a combination of GVD and NSF, controlled underwater compression of optical pulses can be attained."

Comments

underwater lasers?

[myVarNamesAreTooLon]

...but do they have plans to attach them to sharks?

Whale/sonar people are going to love this one

[BigSlowTarget]

I don't know how the audio volume of this system compares with sonar systems (though the article's 220db and 160db from http://www.oceanmammalinst.org/mgpaper.html kind of gives clues and weakly suggest might be as much as 64x), but I suspect the people who oppose the use of sonar by the navy on the theory that it hurts whales are going to go nuts over this one.

There is no where near enough info to actually assess any kind of threat, but I'm sure the panic button will be hit anyway.

Re:Whale/sonar people are going to love this one

[fluffy99]

Active Sonar output is limited by cavitation. That is the boiling of the water on the surface of the transducer, which acts like a blanket attenuating and distorting the output. In general that means under 200 dB. Still plenty to cause problems with local wildlife. Active sonar is not used very often at its also like turning on a spotlight in a dark room.

Re:Whale/sonar people are going to love this one

[anotherhappycamper]

I hope it does push the panic button. It is one thing for us to defend ourselves. It is quite another for us to make another species miserable or extinct while attempting to optimize a way to defend ourselves from our own fears. Public outcry and discussion can give us pause so that we can investigate whether the effectiveness outweighs the possible ethical costs, and hopefully come up with a thoughtful solution.

Re:Whale/sonar people are going to love this one

[drerwk]

Get back to me when there are 6 billion whales with and expected increase of 3 billion over the next decade or so. I would be willing to give up a nation of people if I could put the ocean back the way it was a hundred years ago.

Re:Operational security?

[Vahokif]

Encryption?

And the things living around it?

[Anonymous Coward]

I wonder how many marine animals we'll cause to go deaf from this, which would probably end any chance of survival for those affected. http://www.makeitlouder.com/Decibel%20Level%20Chart.txt 220 decibels is incredibly loud in the air, I can only guess the extended intensity it travel with underwater...

Re:Operational security?

[cwebster]

The issue isnt eavesdropping, its that the mere act of communicating gives your position away to everyone when wants to know.

bad acronym

[Jeek Elemental]

they should call it NSFW (Not Safe For Whales)