from the lasers-not-just-for-blasters-anymore dept.
City College of New York researchers have manipulated the polarization of a laser beam to create shapes that could boost data transmission rates:
Using special devices called "q-plates," the researchers manipulated a laser beam's polarization into novel shapes some of which Milione referred to as "radial" and "azimuthal." "While light's polarization (linear and circular) is used for many modern technologies, such as, 3D television, its shape is often left untouched," he said.
The researchers showed that each shape could carry an additional data stream. While the researchers used only four shapes, in principal, the number that can be used is unlimited. "The amount of data that can be transmitted on a single laser beam can be scaled to terabits or even petabits," said Alfano. "This technology is potentially compatible with building to building communication in NYC or even between Google data centers."
The research is published in Optics Letters [abstract].
(Score: 4, Funny) by DeathMonkey on Monday April 27 2015, @09:50PM
I knew those Republicans would be good for something one of these days!
(relax, it's a joke)
(Score: 2) by rts008 on Monday April 27 2015, @10:35PM
OMG! We are doomed!
Since Republican lawyers are plentiful, next step is Republican sharks with friggin lasers.
You know it's the next step. ;-)
Open(Campaign) season has just started on the citizens...the assault has begun. Pew! Pew! Pew!
(relax, it's still a joke, although YMMV)
(Score: 3, Informative) by VLM on Monday April 27 2015, @09:58PM
http://en.wikipedia.org/wiki/Polarization_mode_dispersion [wikipedia.org]
For every action there's an equal and opposite reaction, sorta.
Just like different wavelengths travel at different speeds in fiber spreading pulses, so do different polarizations.
It will none the less add some capacity of course.
(Score: 4, Interesting) by c0lo on Monday April 27 2015, @11:50PM
The problem that I'd be afraid is mixing polarizations due to imperfections, which would result in mixing communication channels
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Informative) by coolgopher on Tuesday April 28 2015, @04:00AM
Yeah, you don't want to cross the streams. That would be bad.
(Score: 3, Funny) by TK-421 on Tuesday April 28 2015, @01:57PM
Tell him about the Twinkie.
(Score: 3, Interesting) by bd on Tuesday April 28 2015, @07:48AM
I'm afraid it will not add capacity for fiber optics communications, as this method only works in free-space data transmission, due to the usage of higher-order transverse modes (you would have to use multi-mode fibers, and those are suspect to an effect called mode dispersion, completely messing up this signal).
Oh, and it apparently only works over a distance of 1 m, as even the smallest optical table would provide for far more than one meter of propagation length, provided one cleverly uses a bunch of mirrors. I have only read the abstract as I am not at work, but I can only assume they tried and it didn't work.
(Score: 2) by bob_super on Wednesday April 29 2015, @03:53PM
On top of this, the fiber's capacity usually (99.99..%) isn't the problem in current systems.
Demuxing a full set of DWDM wavelengths at 25Gb/s each, still takes so much power that adding twice or four times the capacity in the box is a recipe for meltdown. If you have a long-reach link and can't dig to add more fibers, this kind of trick will help in a few years. But for now, most people are much better off adding another fiber and back-end.
(Score: 4, Informative) by frojack on Monday April 27 2015, @11:54PM
I thought polarization was already widely done in fiberoptics, how is this new.
Signal Separation
http://www.newport.com/Polarization/144921/1033/content.aspx [newport.com]
http://en.wikipedia.org/wiki/Polarization-maintaining_optical_fiber [wikipedia.org]
http://www.newport.com/Tutorial-Polarization-in-Fiber-Optics/849671/1033/content.aspx [newport.com]
Used as filters: http://www.thorlabs.us/newgrouppage9.cfm?objectgroup_id=6100 [thorlabs.us]
No, you are mistaken. I've always had this sig.
(Score: 0) by Anonymous Coward on Tuesday April 28 2015, @03:02PM
If I understand it correctly, the new thing here is that they don't just polarize the light, but they use light patterns that are polarized differently at different parts of the fiber's cross section. That way they get more than the two distinguishable directions polarization normally gives you (note that I'm speaking about distinguishable directions; there are of course more polarizations than two, but they cannot be distinguished, as in, you cannot make a device that detects only one of them and not the other).
(Score: 0) by Anonymous Coward on Tuesday April 28 2015, @06:02AM
Did I understand all this wrong?
So you got a pipe that's a mirror on the inside.
normally you would shot some light from a flashlight thru this pipe.
this is equal to a normal single mode fiber optic cable that can do something like 40 Gbps.
now you take two (2) flashlights and cover them with cardboard:
cardboard one has "Zer0" shape cut out
cardboard two has a "+" shape cut out.
now you shine both flashlights into the pipe and you get both shapes, a "+" inside a circle (Zer0) at the other end.
with some smart detector that is tuned to "Zer0 shape" -or- "+ shape" you can now push 2 (two) times
40 Gbps = 80 Gbps thru the same mirror coated pipe -aka- single mode phiber optic cable?
I think is generally known as multiplexing?
So the news is that they found a new combo of shapes that don't interfere too much with each other so as
to be able to multiplex multiple single 40 Gbps "streams" into one regular single mode phiber optic cable ... or wat?
man ... just don't explain sh1t simple else the sheaples might wake up and lose respect of "big science"?
(Score: 3, Informative) by bd on Tuesday April 28 2015, @08:27AM
Sorry, I am afraid you got this all wrong.
When you focus light of only one color, the smallest thing you could theoretically get has the form of a spot with a diameter that is related to its wavelength.
This is due to something called diffraction.
A single mode fiber is an optical waveguide (a pipe, sort of) that has a diameter that is roughly the size of this spot. Therefore, the light has no wiggle-room in
the fiber and only takes one propagation path through it, countering an effect where the same bit in your data stream takes paths of different length in
your fiber by being reflected at different angles at the same time, therefore having the same bit arriving at different times at the other end of the fiber.
Now, whenever light has structure in it that would, say, create an image of a "+", such an image in the focal plane of a lens would be a "+", that you
can think of as being composed of a lot of these diffraction limited spots. This is a fundamental limit of optics. Now, the single mode fiber will only let one of these dots inside.
Actually, if you would put the fiber on two translation stages, you could create an image of the "+" by moving the fiber. This would be the world's slowest image sensor.
So, whenever something is giving structure to light, such as higher order spatial modes as used in this paper, it means you cannot use it for fiber communications.
The aforementioned effect in multi-mode fibers also distorts the image that you see at the other end of the fiber.
What's more, the so-called beam quality of your light goes down if it contains higher-order modes. This means that it loses the ability of light to stay roughly
the same spot size over a given distance, as all higher-order modes have a larger divergence angle than the fundamental mode (that corresponds to a diffraction limited spot).
This means this method should be not really nice for very long distance free-space optical communications.
Of course, the researchers know this, and probably target a propagation distance where these effects for the modes they are using is not too much of a disturbance.
But it would certainly not work for communications between, say, earth and moon.
Your post contained a quite clever use of the number one for the letter i in the word shit, actually. Did you know you are allowed to use swear words on here?
(Score: 0) by Anonymous Coward on Tuesday April 28 2015, @03:07PM
I think fiber optics is generally unsuitable for earth-to-moon communication.
(Score: 0) by Anonymous Coward on Tuesday April 28 2015, @03:16PM
thanks for the info.
seems i got it wrong ... a bit. i found a good explaination to fiber optic multiplexers here: http://en.wikipedia.org/wiki/Arrayed_waveguide_grating. [wikipedia.org]
seems it is being "shaped" but not with a 2-dimensional cardboard punch out but rather "only" one dimensional.
the one that can potentially do unlimited dimensions seems to be OAM: http://en.wikipedia.org/wiki/Orbital_angular_momentum_multiplexing [wikipedia.org]
the article seems to refer to this OAM thingy ... seems we dont know all and every property of light just yet ... amazing.
(Score: 2) by urza9814 on Tuesday April 28 2015, @02:49PM
That seems to kinda be the general idea as I understand it. Except they're not shaping the signal, they're shaping the *photons*.
Think of a single photon of light like a round plastic bead. Standard polarization would be like taking a belt sander to that bead, turning it into a flat circle. These guys are taking an exacto knife and actually carving shapes into the beads instead.
That's my understanding of this anyway...someone please correct me if I'm wrong :)