Lasers Speak to Subs

Communicating with subs underwater is beyond tough. Sound moves through seawater in very strange ways, with water temperature, salinity, and density speeding up and slowing things down — garbling conversations in the process. Electromagnetic transmissions (like radio) are no better — the sea has some funky electrical conductivity. During the Cold War, sub authority Joe Buff notes, the Navy managed to get super-simple, one-way messages to its subs, with a pair of giant (28-mile!) extremely low frequency transmitters, based in the Midwest. But those transmitters were shut down, a few years back.
DPPS_Beam_Fan.JPGThe Navy’s new idea is to get specially-tuned lasers to handle the job, instead. The service has handed out a pair of small business innovation research contracts to Bothell, WA’s Aculight Corporation and Bedford, MA-based Q-Peak to build blue-green, quick-burst lasers for transmitting messages across the deep. Acluight, for example, wants to use a combination of semiconductor and fiber lasers to produce a low power beam (around 10 watts) at about 532nm spectrum range. The idea is to get pulses as quick as half a nanosecond, repeating as much as 10 million times per second.
Blue-green lasers have been discussed for a while as potential sub-talkers, with good reason. Seawater has a lot of organic junk floating around inside, which makes it “turbid” — “nearly opaque to light over much of any distance,” Buff explains.

Blue-green light’s frequency is best at penetrating through this turbidity, given the mix of sizes in microns of the particles and other stuff that prevents seawater from being transparent. (Of course, some areas such as the Bahamas are famous for the clarity of their water, but this is very much the exception, not the rule, globally speaking.) This same turbidity is essential to giving submarines their invisibility while submerged, so it’s a double edged sword.

  • Robot.Economist

    I could see lasers as a useful transmittal medium under the thermocline (where light no longer penetrates the water). In a pitch black environment, recievers could afford to be hypersensitive to light, which would improve message fidelity.
    On an unrelated note, has one seen reporting on laser-emitting microchips that surfaced in the media yesterday? That seemed like a pretty big breakthrough.

  • DS

    If the source of the laser communication were a stealth satellite, you’d have a completely secure method of communication which would bypass alot of ‘middlemen’. In addition, I’m sure the laser light would become somewhat diffuse upon hitting the surface of the water, so the sub would not have to have super sensitive sensors to pick up a ‘flickering’ at a particular frequency in the water surrounding it. That ‘flickering’ frequency would be another layer of security. Cool stuff.

  • DS

    orrrrr…you could just have sharks with freakin lasers mounted on their heads.
    :)
    (comeon’, you knew someone was going to say it…)

  • Matthew

    I like the guy’s comment about the security aspect of having lasers that flicker.

  • lawrence stanley,sr.

    As a Signal Corps.—member in early 50’s. We could have used>>”””laser weapons”””—Someone design weaponry for our military-NOW-!!! IF COMMUNICATIONS-via Laser-WORKS OUT-?? I say this-“”GIT HER DONE””-yessiree—acer28

  • c. a. miller

    IF this was going to be a viable option Still at this point… we would NOT be hearing about it NOW

  • N. R. Glenn

    If we have the tech. capability to aim lasers both from space to the ocean, and the reverse, I say go for it. Unfortunately, this seems somewhat like hitting a golf ball with a b-b gun at 10 miles distance, even allowing the b-b gun the ablility to do this. Adding the effect of water waves, this now appears extremely difficult.

  • Bill Eichner Nobel Nominee

    A solution of chromium dioxide (inert) and carbon sulfate will prolixly yellow dilithium crystals equally and allow them to them to radiate equally in all directions to infinite distances thus turning the turbid ocean waters into a crystal clear environment suitable for laser communications.

  • K Goetowski

    George, dilithium and higher numbers of covalently bonded lithium atoms do exist in the real world, albeit in small quantities. It has been observed, for example, that 1% of lithium in the vapor phase (by mass) is in the form of dilithium. Clusters of lithium atoms also exist; the most common arrangement is Li6.

  • George

    I’m glad K. Goetowski that you can copy and paste from Wikipedia.com.

  • Clayton

    Thermocline has to do with temperature not where light stops penetrating the water..
    ther?mo?cline? /???rm??kla?n/ Pronunciation Key - Show Spelled Pronunciation[thur-muh-klahyn] Pronunciation Key - Show IPA Pronunciation

  • J. Yale

    George’s first comment is about the only one that even worthwhile. I actually work on submarines for the US Navy. So just know he is more on the dot than your crazy little sci-fi babble could ever be. That is all..

  • George

    I’m glad K. Goetowski that you can copy and paste from Wikipedia.com. You obviously did not understand what you’ve read. Bill Eichner Nobel Nominee wrote “dilithium crystals.” If you would have read that and understood what you plagiarized from Wikipedia, then you would know and I’ll qoute Wiki. “This article is about a fictitious substance”(in reference to the crystals of course), “Dilithium is a fictional crystalline mineral in the universe of Star Trek.” Bill wrote “dilithium crystals” refering to a “solution” (liquid, not gas).

  • Chuck Haas

    Hmmmm, seems that floating a really small sensor to the surface that could receive laser and radio transmissions would be easier, and probably a whole lot cheaper. Now it would be even better if the sensor was disguised as some flotsam and jetsam. Drift wood or plastic items would work nicely and would not arouse suspision, unless foreigh navies want to start worriying about all the drift wood out there. Of course, the sub could not be going 30 knots at the time, but what the heck. Seems like they don’t need to be going 30 knots all the time anyways.

  • Frank ETC(SS/SW) Ret

    What you all seem to missing is that this is a one way solution right now - the laser is not aimed at a submarine but is swept across the ocean. The light from laser is diffused out from it’s impact point by the turbidity of the sea. External sensors detect the laser and in a mere fraction of a second would get all the info needed ( higher frequency = higher data rate ). Yes - high power lasers are required but the article is talking in the 10’s of watts - totally achievable by bundling output from multiple solid state lasers. This technology has been in development for YEARS people. In conclusion 1. the submarine does not have to surface to get comms with this method and 2. next time please read and reread the article you are commenting on until you UNDERSTAND IT before you give comments F. R. H. ETC(SS/SW) Retired Electronics Technican Chiefg Petty Officer - Submarines Qaulified and Surface Warfare Qualified - Retired - Been There - Done That _Wore the T-Shirt ouit years ago

  • DAN

    i think what george said avout you guys sounding like idiots was really on the dot. Im an electronic student, and don’t know a whole lot, but still thought most of you sounded like you didnt have a clue about what you were saying. with some exceptions. and it is true that new technology does take some time to perfect, or better, and it would take some time, with costs and ideas to come up with, but i think that in the near future, that this not only would work out, but be used at least on a small scale.

  • Cob MMCM(ss)

    Your article on the lasers and submarines is “old hat”. As someone who has earned his way through Uncle Sam’s Canoe Club, I can speak specifically that this is something which was under development MANY years ago. What’s MORE important is do not try to figure out what we are doing now. We are called the “Silent Service” for a reason. For my shipmates’ protection, focus on other places. We’ll deal with the needs of the boats.

  • jason

    Actually, one technology that was recently tested was one that involved Einstein’s “spooky action at distance” theory. Simply, there were two particles that had some unique attraction between them and regardless of the distance between them if one was interacted with then the other responded likewise. Imagine instaneous digital communication that dosn’t transmit a signal that we can currently intercept, but nevertheless if one particle is interacted, then the other responds as well and there is no EM signature. Hmmmmm spooky…
    Just a thought from an old ex-nuclear knuckle dragger from the IKE.

  • Junior

    Not bad. I think I will do some research on these two companies. I’ve been itching to expand my portfolio. This could work….in theory.

  • Howard Evans

    There are “only” two problems that must be solved to communicate with deep subs moving at speed: (1) get a large enough signal with sufficient bandwidth to reliably detect and receive meaningful messages; (2) encrypt the signal in a manner that defeats all interception and decryption attemps as well as “spoofing” by foes attempting to send fake messages. It is pretty safe to say that the Navy, with help from the NSA, has the encryption problem “nailed” so now the only thing left is how to get the message through. Forget quantum entanglement, a laboratory curiosity that does not solve the communcations problem. Blue-green laser light? Certainly, if the peak pulse power is large enough, the spectral emission line is narrow enough, and a synchronous detection system is employed to reject all the surrounding optical “noise” while accepting only the “signal” component. This doesn’t have to be a one-way sky-to-sub system like ELF either. Nor does it require satellites in geosynchronous orbits. What it will require is a heck of lot of engineering and a substantial amount of time and money to develop, field, test, and qualify before putting it on the fleet. It does take the Navy about twenty years to float a new boat, or the Air Force to launch a new plane, or the Army to field a new tank. Who knows where we are in the production cycle for this “new” concept? I do know that thirty years ago we were looking at copper-vapor “blue-green” lasers to do this job. Since then there has been a microelectronics sea change in technology that has enabled stuff most people cannot imagine. So it may not take another “twenty years” to put this “new” concept into practice because we have already been working on it for at least thirty years.

  • Frank H Rivers

    I built one of the transmittal devices that your speaking about,over 30 years ago. I tryed to sell it but did not have any luck(even to a private school.

  • STEVE AQUININGOC

    Has anyone thought about the effects of this laser on marine mammals, like the Orcas??

  • Gary

    Jason:
    Nickoli Tesla,early 1910’s, communicated instantaneously across vast distances (globally).
    Lazer is nice; but Mr. Tesla, talked to anyone at anytime; he wanted to; if they had his equipment.
    Even underground.
    So I’m not so sure that the use of lazer is so unique; if not outright too expensive and technically backward!

  • xshipdriver

    The Submarine Laser Communications Program (SLC) was terminated in 1986/7. It was ended not because it was impossible but because the state of art was not sufficiently advanced to be able to use “off the shelf” electronics and the cost of developing the equipment as well as confirming the science (not to mention solving the inevitable “program stoppers”) was too high for the Navy to bear at the time. Other forms of communications were available which met USN requirements. It is apparent that these other forms are not as private as they once were. The compelling feature of the SLC program was its pinpoint connectivity. It didn’t need to scan the whole ocean, it pointed a pencil beam where the sub looked at prearranged times. Intercepting the beam means the intercepting unit has to be within the beam’s downlink footprint, a very small area. If the opposition is in the same space as the sub, the sub knows it. Therefore, no covert intercept.

  • Career DoD

    This website continues to attract more than its fair sure of whack jobs; so does submarine laser communications.