Extraordinary Light

Has science taken a wrong turn? If so, what corrections are needed? Chronicles of scientific misbehavior. The role of heretic-pioneers and forbidden questions in the sciences. Is peer review working? The perverse "consensus of leading scientists." Good public relations versus good science.

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Re: Extraordinary Light

Unread postby Goldminer » Mon Nov 26, 2012 12:14 pm

seasmith wrote:light as charge dispersion


But what I was thinking was that a measurable amount of pressure is detectable at any surface to which light is applied, but also that light is the result of field compression, collapse, or a potential drop,…” -web


No argument there.
One might consider some “compression, collapse or …drop” as the longitudinal vectors of a light ‘beam’,
which seem always to manifest along with a transverse component as well.
These composite radiations are observed to relay spin and (angular/orbital) momentum onto intersecting bits of matter and so are lasers routinely used to squeeze, relax, deflect or otherwise manipulate, on a nano scale.
A cross-sectional image of a piezo~photonic impulse (hammerhead) would be the two at top of this page.
http://www.photonics.com/images2/Website/2012/2012-10/OPTO-OpticalVortices3.jpg
Or, imagining it with some depth, as a cymatic evolution over a duration.

In this particular instance, the pulse conveys spin which, depending on rate of precession about its longitudinal axis, expresses frequency. [There may be no such thing as light free of spin/polarization, unless it’s the mythical clear light, who knows?]

Upon encounter with plasma or some dielectric at electron scale, an excitation or ‘phonon’ is generated (perhaps at the electron’s magneto-sheath where double-layer interface ‘zones’ electrically pinch), and is imparted its own quantum of momentum, that then may be ejected to propagate as a plasmon/photon [nano-quasar scale].
All ammo for the piezo-photonic physicist.

Image


IMHO, your rotating augur depiction of a light wave here at the bottom of your post is a bit misleading (I assume that is what it is supposed to represent). If the wave rotated as it traveled, it would not appear to rotate as it is intercepted/received/detected. (The flights of the augur would just create two slits through which the wave would travel. It would screw itself into the detector.) On the other hand, if the light wave flights were fixed longitudinally, i.e. non-rotating, as it proceeded through space, it would then appear to rotate at reception. It is the rotation-at-reception that is detected, meaning that the wave does not rotate as it travels. That fact may interfere with the "spinning photon" visualization.
I sense a disturbance in the farce.
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Re: Extraordinary Light

Unread postby seasmith » Mon Nov 26, 2012 12:52 pm

IMHO, your rotating augur depiction of a light wave here at the bottom of your post is a bit misleading (I assume that is what it is supposed to represent). If the wave rotated as it traveled, it would not appear to rotate as it is intercepted/received/detected. (The flights of the augur would just create two slits through which the wave would travel. It would screw itself into the detector.) On the other hand, if the light wave flights were fixed longitudinally, i.e. non-rotating, as it proceeded through space, it would then appear to rotate at reception. It is the rotation-at-reception that is detected, meaning that the wave does not rotate as it travels. That fact may interfere with the "spinning photon" visualization. -Goldminer


It is the double image at top of previous page that i was referring to.
[never know when a post is going to start a new page...]
Image

viewtopic.php?f=8&t=3890&start=15

Unlike the twirlygig cgi toy you mention, this one is an actual photodetector snapshot (stopped in time).
It probably doesn't rotate any more than does an active cymatic 'surface'.
"Depth" can be translated as 'momentum', or what ever one wants to call the forces applied in LASER tweezers, cavities, traps, pumps, rotators and etc.
imo
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Re: Extraordinary Light

Unread postby Goldminer » Mon Nov 26, 2012 1:34 pm

seasmith wrote:
IMHO, your rotating augur depiction of a light wave here at the bottom of your post is a bit misleading (I assume that is what it is supposed to represent). If the wave rotated as it traveled, it would not appear to rotate as it is intercepted/received/detected. (The flights of the augur would just create two slits through which the wave would travel. It would screw itself into the detector.) On the other hand, if the light wave flights were fixed longitudinally, i.e. non-rotating, as it proceeded through space, it would then appear to rotate at reception. It is the rotation-at-reception that is detected, meaning that the wave does not rotate as it travels. That fact may interfere with the "spinning photon" visualization. -Goldminer


It is the double image at top of previous page to which I was referring.
[never know when a post is going to start a new page...]
Image

viewtopic.php?f=8&t=3890&start=15

Unlike the twirlygig cgi toy you mention, this one is an actual photodetector snapshot (stopped in time).
It probably doesn't rotate any more than does an active cymatic 'surface'.
"Depth" can be translated as 'momentum', or what ever one wants to call the forces applied in LASER tweezers, cavities, traps, pumps, rotators and etc.
imo


Yes, I am referring to that picture, in addition. I think it proves my point. Any picture is going to require a duration of time to absorb the incoming light (stopped in time is a bit of a misnomer, in this case, since it is recording the incoming series of positions of the "flights." So, the picture shows the rotation of the incoming flights over time, which wouldn't appear if the incoming flights were rotating, since the rotation would be multiple exposure of the flights all fixed at one angle, in one place. As the frequency of light changes, so does the number of wavelengths in a given distance. Your view, (it seems to me) is that the "spinning flights" spin faster or slower according to the frequency. My view is that the waves are emitted "scrunched together" or "stretched apart," according to the frequency. This allows for the Doppler shift, as detected by moving observers. How would motion of a detector make the incoming spin of a photon speed up or slow down, relative said detector?

P.S. The two spirals in the pictures are twisting the same direction.
I sense a disturbance in the farce.
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Re: Extraordinary Light

Unread postby seasmith » Mon Nov 26, 2012 5:59 pm

Any picture is going to require a duration of time to absorb the incoming light (stopped in time is a bit of a misnomer, in this case, since it is recording the incoming series of positions of the "flights."


They are static interference patterns ie standing waves, so duration will not much change the recording. The "depth" i'm alluding to is more like intensity or density of information, somewhat like an exposure on an old silver nitrate? photographic film.

So, the picture shows the rotation of the incoming flights over time, which wouldn't appear if the incoming flights were rotating, since the rotation would be multiple exposure of the flights all fixed at one angle, in one place.


The apparent rotation of phase is manifest in the empirically real Effect. {google "spin-rotation laser"}

Your view, (it seems to me) is that the "spinning flights" spin faster or slower according to the frequency.


No. I think that phase propagation, in a coherent laser beam, is mostly independent of frequency; at least before significant interference takes place.

How would motion of a detector make the incoming spin of a photon speed up or slow down, relative said detector?


No idea. Perhaps it would depend on which of the many types of photo-detectors in use....

P.S. The two spirals in the pictures are twisting the same direction.


Yes, they are interference patterns, like a cymatic surface.


Here's a little better description of their experiment:
http://www.photonics.com/Article.aspx?AID=52139
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Re: Extraordinary Light

Unread postby Goldminer » Thu Nov 29, 2012 12:43 am

seasmith wrote:
Any picture is going to require a duration of time to absorb the incoming light (stopped in time is a bit of a misnomer, in this case, since it is recording the incoming series of positions of the "flights."


They are static interference patterns ie standing waves, so duration will not much change the recording. The "depth" i'm alluding to is more like intensity or density of information, somewhat like an exposure on an old silver nitrate? photographic film.


I had read the whole thread at least a couple of times, but not again before posting the last thoughts of mine. I don't know if that would have made a difference except in your pointing out that the pictures are interference patterns. I have no idea now what I thought they were as I wrote the post. So, yes, standing interference patterns would not be blurred as recorded over time, whether regardless the medium, photographic film or ccd.

seasmith wrote:
Goldminer wrote:So, the picture shows the rotation of the incoming flights over time, which wouldn't appear if the incoming flights were rotating, since the rotation would be multiple exposure of the flights all fixed at one angle, in one place.


The apparent rotation of phase is manifest in the empirically real Effect. {google "spin-rotation laser"}


I did search "spin-rotation laser" and what I gather is not that light is "spinning," but that protons, electrons, atoms, and molecules are made to spin utilizing the laser energy. The resultant radiation from said resonances has peculiar characteristics. The latest atomic clocks have increased stability by using "laser cooling," which actually uses laser energy to "cool" just as all other refrigeration devices "transfer" heat by using energy.

seasmith wrote:
Your view, (it seems to me) is that the "spinning flights" spin faster or slower according to the frequency.


No. I think that phase propagation, in a coherent laser beam, is mostly independent of frequency; at least before significant interference takes place.


Lasers & Masers produce coherent single frequency radiation.
My understanding is that this means all "waves in the beam are "in phase," and all are "waving" at the same frequency. My understanding is that "phase interference" can happen several different ways. For example waves 180 degrees out of phase become invisible, even though the power is still being converted. Single side band radio transmission "cancels" or filters out the "carrier," which reduces the power needed to transmit the signal, however no information is received unless the "carrier" frequency is reintroduced at the receiver. (my understanding is that the side bands do vary in amplitude and frequency. Phase modulation in itself is another method of information transmission. Just muttering to myself. )

seasmith wrote:
Goldminer wrote:How would motion of a detector make the incoming spin of a photon speed up or slow down, relative said detector?


No idea. Perhaps it would depend on which of the many types of photo-detectors in use....


Detectors just remove a small amount of energy from the beam or ray. This just makes a shadow in the beam. Just as it is the speed of the detector that causes Doppler shifting. Several types of detectors can detect the same beam, but of course not all in exactly the same place. EMF radiation from different sources can occupy the exact same space, unlike matter and the constituents of matter.

This thread on extraordinary light is very interesting, and I certainly understand very little about it. I am just trying to incorporate what I think I know with what the gurus are saying happens.

seasmith wrote:
Goldminer wrote:P.S. The two spirals in the pictures are twisting the same direction.


Yes, they are interference patterns, like a cymatic surface.


Thanks, I think I understand mo' betta'.

seasmith wrote:Here's a little better description of their experiment:
http://www.photonics.com/Article.aspx?AID=52139
[/quote]
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Re: Extraordinary Light

Unread postby seasmith » Sat Dec 01, 2012 11:54 am

I did search "spin-rotation laser" and what I gather is not that light is "spinning," but that protons, electrons, atoms, and molecules are made to spin utilizing the laser energy. The resultant radiation from said resonances has peculiar characteristics.


That's why i capitalized Effects.
To cymatics again, the incident sound energy is volumetric and a complex morphology of harmonics and null-onics. The particulates at the cymatic 'surface' are driven by that confluence of forces and exhibit a sort of ~skeleton of that volumetric progression.
Another macro-scale analogy (without the so-called 'quantum' effects in nano and sub-angstrom scale light experiments) might be the force of a river current: invisible to us, tho the frothy whirlpool, rippled sand bottom, rounded stones and cut banks are readily apparent.
Not saying a light beam is a river, just that forces are only known by their effects
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Re: Extraordinary Light

Unread postby seasmith » Wed Dec 19, 2012 6:51 pm

http://www.nature.com/nature/journal/v492/n7427/full/492051a.html

Sheet lasers as Optical “Trampoline” surfaces:


“Previous optical-manipulation techniques have used thermophoresis to trap and control solid particles such as carbon4. Esseling et al. …by using sheets of laser light instead of simple laser beams, have produced a surface made of light off which liquid droplets can bounce.




A luminous surface with emission in 3 orthogonal planes of space.
[ to cover all the motions, can’t we just call the fourth dimension electricity, with its 3 elements of amplitude, frequency and phase?];
so here imaged a laser broadside, in air: Image

Ashkin showed that by using a laser he was able to push objects such as glass beads immersed in water and droplets of liquid dispersed in air along the direction of propagation of the laser beam. This radiation pressure could also be used to trap particles by holding them against gravity or, by using two counter-propagating beams, to confine them where the radiation pressure from each beam balanced. [and impart complex motion -s]

The idea that light could exert these forces was nothing new: James Clerk Maxwell had predicted3 it as a consequence of his electromagnetic theory nearly 100 years previously. However, observing the effect had proved difficult owing to the problem of distinguishing optical forces from thermal effects. Indeed, William Crookes (of Crookes radiometer fame) was able to demonstrate thermal forces on matter in 1901, long before optical forces were definitively observed.

Ashkin's great insight was to understand that, by using optically transparent microscopic objects, he could rely on the forces generated by scattering, reflection and refraction alone and remove the strong, masking thermal forces. His work has led to many applications, with optical-trapping techniques being widely used for studying minuscule forces and microscopic motion in systems ranging from molecular motors to the evaporation dynamics of…


Nature vol 492 D. Mcgloin
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Re: Extraordinary Light

Unread postby seasmith » Thu Dec 20, 2012 7:12 pm

Your view, (it seems to me) is that the "spinning flights" spin faster or slower according to the frequency.
-Goldminer

No. I think that phase propagation, in a coherent laser beam, is mostly independent of frequency; at least before significant interference takes place. [or interaction] -s


There is a caveat, when more than one laser source is present, for phase matching/phase locking.

When phase matching is achieved, the group velocities of the interacting waves are in general still not matched; there is a certain group velocity mismatch, which limits the interaction length for pulses and (for a given interaction length) the spectral range [ie frequency -sea] (called phase-matching bandwidth) in which phase matching is achieved.


Also:

Note that phase matching is in some cases further complicated by the Kerr effect: the resulting intensity-dependent refractive indices also make the phase-matching relations intensity-dependent, and this effect is sometimes significant, e.g. for four-wave mixing processes in fibers.

http://www.rp-photonics.com/phase_matching.html
http://www.rp-photonics.com/kerr_effect.html
http://www.rp-photonics.com/four_wave_mixing.html


So, in the context of any dielectric media of propagation, with their various inherent dielectric quotients (or "Q factors" if solid-state),
amplitude (intensity), frequency (color) and phase (precession/nutation angular momenta) are ultimately interdependent.

Furthermore, i would theorize, that frequency and phase are fractallating perturbations of an (ideal/DC power) amplitude. Evidence for which is the fact that the total Plank energy of an EM/ES emission is proportional to the square of its amplitude.
~
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Slow Light

Unread postby Lloyd » Fri Feb 01, 2013 8:35 am

Slow Finding on Slow Light
I hadn't heard of slow light before, but I saw the tv show The Universe last night on the H2 History channel, the title was Deep Freeze. Toward the end was mentioned these statements paraphrased, now on Youtube at http://www.youtube.com/watch?v=OjoW2kdQ8Q4 (at 36 min. mark) by Alex Filippenko, UC,Berkeley; Luciana Walkowicz, Princeton U say: The lowest temperature reached is half a nanoKelvin. At such temperatures atoms clump together and synchronize motions, all behaving the same way. These super cold substances can stop light in its tracks. We can stop a beam of light, or slow it down, play with it and release it again. You can stop light, turn it into an electrical signal, and then release it and turn it back into light, which has all kinds of applications in electronics.

Now I see that SeaSmith had already discussed this at http://thunderbolts.info/forum/phpBB3/viewtopic.php?f=8&t=3890#p42834 on the 4th post of this thread over 2 years ago. Before I saw that I had found some info online, some from around 1999 and some from 2009 or so. I'll post below what I found. I think Mathis says light speed is the speed that photons happen to be moving on average or something. They can go faster or slower, but the other photons tend to make them adjust to the average, like if you drop a drop of water in a stream, the drop will soon have the same speed as the nearby molecules, due to collisions.

Researchers have trapped a laser pulse inside a glass chamber --and released it again intact. Such command of light could lead to mind-boggling new technologies.
http://science.nasa.gov/science-news/science-at-nasa/2002/27mar_stoplight/
... Yet until recently there was one thing we couldn't do with light: pause it. Stopping light in its tracks and releasing it again unchanged was beyond human ken.
- But now scientists have figured out how to do even that.
- Last year, physicists at Harvard University shined a laser beam into a glass cell filled with atomic vapors. The light went in, but it didn't come out again. It was not destroyed or absorbed, but rather stored -- ready to emerge intact at the scientists' bidding.
- The laser pulse was kilometers-long before it entered the cell, yet the pulse fit intact within the centimeters-wide chamber. Sound like magic? Perhaps ... but it was only quantum mechanics.
- Quantum mechanics describes the bizarre rules of light and matter on atomic scales. In that realm, matter can be in two places at once. Objects can be particles and waves at the same time. And nothing is certain -- only probable or improbable.
- This improbable feat -- stopping light -- was accomplished by two teams. One was led by Ron Walsworth, a physicist at the Harvard-Smithsonian Center for Astrophysics, and the other by Lene Hau of Harvard University's Department of Physics. Walsworth's group used warm rubidium vapors to pause their laser beam; Hau's group used a super-cold sodium gas to do the same thing.
- Below: Before she managed to stop light altogether, Lene Hau and colleagues first slowed it to bicycle speeds in 1999.
- Photons -- that is, particles of light -- are massless, and that's why they can travel so fast. The Harvard researchers stopped their laser beams by "weighing the photons down."
- The technique requires two lasers: a "control laser" and a "signal laser." The signal laser is the one to be stopped. Using the control laser, Walsworth's team caused rubidium gas in the glass cell to become "dispersive" -- in other words, the velocity of light passing through the gas depended sensitively on the color of the light. (Prisms work much the same way, although the analogy is not exact.) In such a dispersive gas, atoms and photons interact strongly, says Walsworth. "Effectively dragged down by strong interactions with atoms, the photons slowed to a crawl." Physicists call such an atom-photon system a "polariton."
- Next they reduced the intensity of the signal laser until the polariton was 100% atomic. There were no photons left inside the chamber. Yet the imprint of the photons remained -- on the atoms themselves. Like a child's top, atoms spin. (Physicists say they "carry angular momentum.") Information describing the fading laser pulse was stored, like a code, in the up-and-down patterns of the atoms' spin axes.
[see caption]
- Above: As the laser pulse enters the chamber containing the rubidium vapor, the information that defines the light becomes imprinted on the atoms' spin states (indicated by the small arrows). In the moment that the light is "stopped," only the spin states exist. This image by Tony Phillips is based on another from the American Institute of Physics.
- Freeing such a stored pulse is easy: another laser beam directed through the chamber can release it. "In the near future, this technique may enable efficient, reversible mapping of quantum information between light and atoms," says Walsworth.
[see caption]
- The possibilities are mind-boggling: "Suppose you have some information encoded in atoms," says Walsworth. "You could map that information onto light, send it over to some other group of atoms, and imprint the information there." Walsworth calls this "quantum communication."
- Computers do their work using binary numbers -- that is, ones and zeros. Such "bits" are in constant motion inside your desktop PC. In a quantum computer the bits -- called qubits -- could be carried from place to place by photons. Horizontal polarization, for instance, might represent "0" and vertical polarization "1". (It doesn't end there: Qubits can be 0, 1, or a superposition of the two -- it's allowed by quantum physics! Qubits are natural tools for "fuzzy logic." )
- Such a computer would work only if there were some way to stop light, change its state, and send it on its way again. Walsworth's team has demonstrated just such a sequence: While a light pulse was imprinted on the rubidium atoms, they made a simple change to the atoms' quantum states. Much to the researchers' delight, those changes were present in the regenerated light pulse.
[see caption]
- Walsworth and Hau used vapors (rubidium and sodium) to pause light. Will the insides of quantum computers be vaporous as well?
[Right: Supercomputer; Roger Ressmeyer.]
- Maybe not: A group led by Phillip Hemmer of Hanscom Air Force Base (he is now at Texas A&M University) has shown that light can be stopped as well by solids. They used a rare-earth doped insulator -- a type of material generally used for ultra-high density optical memories and processors.
- "It's very nice to think that it works in a solid state, which is moving more towards the electronics that we're familiar with," Walsworth says.
- In a strange new world where scientists can stop light, hold it, and release it at will -- familiar is good.


"Slow Light"
http://sciencewatch.com/nobel/predictions/slow-light
It is now well known that the optical properties of matter can be changed dramatically, to the extent that an opaque object is made transparent over a narrow range of wavelength within an absorption line. This is achieved by using a laser control beam or “pump” to clear an atomic window through the absorption region of a gas. A second laser beam can then pass through unhindered. Electromagnetically induced transparency (EIT) involves cooling sodium atoms almost to absolute zero, creating a Bose-Einstein condensate that behaves as if it were a single atom. In their 1999 paper titled “Light speed reduction to 17 metres per second in an ultracold gas,” Lene Hau and Stephen Harris describe how they used EIT to slow optical pulses to the speed of a bicycle. Then in 2001, Hau and her team at Harvard brought laser light pulses to a standstill for a thousandth of a second in a magnetically trapped ultracold cloud of sodium atoms. In her native Denmark....


Slowed light breaks record
http://physicsworld.com/cws/article/news/2009/dec/15/slowed-light-breaks-record
- EIT [electromagnetically induced transparency] is a phenomenon in which certain media that do not usually transmit light at a certain wavelength can be made transparent by applying light at a slightly different wavelength. EIT can be used to slow down a pulse of light so that it could effectively be "stored" in a medium. The first person to see EIT in an atom cloud was Stephen Harris at Stanford University in 1991, and he went on to slow light by a factor of 100 in 1995. Then in 1999, Lene Hau and team at Harvard University managed to slow light by a factor of 30 million. They used a Bose–Einstein condensate (BEC), which is a gas of atoms that is so cold that all the atoms settle into a coherent quantum state.
- Now Hau and team have used a BEC of sodium to store light for over one second. The atoms were chosen because they have a specific configuration of three energy levels. Transitions between the two lowest levels (1 and 2) are forbidden – but transitions can occur between either 1 or 2 and the highest-energy level (3).
...
Slowed to 25 km/h
- Although this separation process involves distorting the pulse-storing BEC – and hence the nature of the revived pulse – it is completely deterministic, which means that no quantum information is lost. By doing so, the team was able to store the pulse for up to about 1.5 s, shattering the previous record of about 600 ms. Furthermore, the fidelity of the revived pulse – the ratio of output energy to input energy – was more that 100 times better than previous systems.
- Another remarkable aspect of the experiment is that the probe pulse – which is about 1 km long in air – is compressed to a drop just 20 µm in length as it travels through the BEC at about 25 km/h.
- One possible application for the system is a "quantum repeater", which would allow pairs of entangled photon states to be separated by more than the 100 km or so that is now possible using optical fibres. Under this scheme, a succession of pairs of atom clouds, separated by short distance and storing entangled photons, could be manipulated and combined to extend the stored photon entanglement over long distances. This capability could be important for developing quantum cryptography systems.
- Hau told physicsworld.com that the technique could be adapted to process the information contained in the pulse. For example, the drop could be split into two before revival – which would create two entangled pulses of light. Another option, according to Hau, is that only one of the drops is revived – creating a pulse of light that is entangled with the remaining atoms. Another possibility is the creation of "squeezed" light pulses, in which the number of photons in the pulse is set by the number of atoms in the BEC.
- According to Hau, the storage time could be increased to as long as 5 s by boosting the stability of the magnetic field used to separate the BEC. However, she also points out that the lifetime is ultimately limited by the tendency of the atoms to join together to form metallic molecules.
- The work is reported in Physical Review Letters.


See also http://en.wikipedia.org/wiki/Lene_Hau
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Re: Extraordinary Light

Unread postby seasmith » Fri Feb 01, 2013 11:39 am

L,

So far, all the slow/stop light experiments have used a BEC- Bose-Einstein Condensate as the resister, or more accurately memrister.
The BEC is created in an MOT- Magneto-Optical Trap, which is a super cold cavity containing some atoms. "Condensate" here just means that the atom's inherent vibrations are slowed to the point where their discrete structure decomposes, and the group then acts as a single unit, somewhat like a school of anchovies or flock of starlings (and the word "quantum" is squandered again...).

The optics are a set of orthogonally intersecting, tuned, laser beams (coherent light).
The magnetic is typically a variable, quadrupolar field.

What i think is going on here, in crudely simple terms, is that the atoms are entrained in the 3D lattice of the interfering laser beams, into a correlated Phase (spin/orbit/nutation). volumetric cymatics ?
The signal beam energy then couples with the optic/atomic lattice-work,
and is coiled or 'curled' by the magnetic flux, thus storing and recording the signal pulse.
A bio-analogy might be DNA, where information is digitized and coiled in storage for a time.

s
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Re: Extraordinary Light

Unread postby StandingWave » Mon Feb 04, 2013 10:34 pm

Bob Shaw wrote a fantastic series of short SF stories about just such an idea as has now been realised: https://en.wikipedia.org/wiki/Bob_Shaw - I loved this series when I discovered it as a kid. Exciting to see it becoming a reality!
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Re: Extraordinary Light

Unread postby webolife » Thu Feb 07, 2013 4:51 pm

Yeah, mostly what seasmith said.
I agree that the BEC acts as a storage device for the pulse energy which is retrieved after a delay occurring within the dense lattice of the BEC field. The relay of the pulse is thereby delayed, but tis doesn't obviate that light stuff zipping throught the BEC was "slowed down" by it as per usual description and diagrams.
Truth extends beyond the border of self-limiting science. Free discourse among opposing viewpoints draws the open-minded away from the darkness of inevitable bias and nearer to the light of universal reality.
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Re: Extraordinary Light

Unread postby seasmith » Thu Feb 14, 2013 6:11 pm

EOT update:


The world's most sensitive plasmon resonance sensor inspired by ancient Roman Cup


Image

Gartia explained that light-matter interaction using sub-wavelength hole arrays gives rise to interesting optical phenomena such as surface plasmon polaritons (SPPs) mediated enhanced optical transmission (EOT). In case of EOT, more than expected amount of light can be transmitted... surface plasmon resonance (SPR)

According to the researchers, most of the previous studies have mainly focused on manipulating in-plane two-dimensional (2D) EOT structures such as tuning the hole diameter, shape, or distance between the holes. In addition, most of the previous studies are concerned with straight holes only. Here, the EOT is mediated mainly by SPPs,

“Our current design employs 3D sub-wavelength tapered periodic hole array plasmonic structure. In contrast to the SPP mediated EOT, the proposed structure relies on Localized Surface Plasmon (LSP) mediated EOT,” Gartia said. “The advantage of LSPs is that the enhanced transmission at different wavelengths and with different dispersion properties can be tuned by controlling the size, shape, and materials of the 3D holes. The tapered geometry will funnel and adiabatically focus the photons on to the sub-wavelength plasmonic structure at the bottom, leading to large local electric field and enhancement of EOT.



http://www.nanowerk.com/news2/newsid=29 ... gy+News%29
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Re: Extraordinary Light

Unread postby seasmith » Sat Feb 16, 2013 6:43 pm

~
A new take on "slow light", (not stopped light), involving photonic (not chemical) absorption:

Rainbow Trapping in Hyperbolic Metamaterial Waveguide

Published 13 February 2013

The recent reported trapped “rainbow” storage of light using metamaterials and plasmonic graded surface gratings has generated considerable interest for on-chip slow light. The potential for controlling the velocity of broadband light in guided photonic structures opens up tremendous opportunities to manipulate light for optical modulation, switching, communication and light-matter interactions. However, previously reported designs for rainbow trapping are generally constrained by inherent difficulties resulting in the limited experimental realization of this intriguing effect. Here we propose a hyperbolic metamaterial structure to realize a highly efficient rainbow trapping effect, which, importantly, is not limited by those severe theoretical constraints required in previously reported insulator-negative-index-insulator, insulator-metal-insulator and metal-insulator-metal waveguide tapers, and therefore representing a significant promise to realize the rainbow trapping structure practically.



Slow-light chips are believed to be promising for enhanced optical buffering, signal processing, and enhanced nonlinear optics. Unfortunately, the observation of slow light in conventional schemes based on Bose-Einstein condensates1 or atomic vapors2 imposes severe constraints in experimental conditions, including narrow bandwidth, limited working wavelengths and strong temperature dependence. The slowed modes are difficult to be implemented into other materials or devices to develop practical applications. Consequently, solid-state nanophotonic structures that can achieve the slow light effect under room temperature are of particular interest3, 4, 5. Recent theoretical and experimental investigations on the “trapped rainbow” storage of light waves in metamaterials6 and plasmonic structures7, 8, 9, 10 have generated considerable interest since various solid-state materials can be introduced in the design of nanostructures to trap electromagnetic (EM) modes. With the ability to produce highly confined and localized optical fields, it is believed that the conventional rules for light-matter interactions need to be re-examined, and new regimes of optical physics are expected. To develop applications based on this intriguing broadband slow light effect, various architectures have been proposed, including surface graded metallic gratings9, 10, insulator-negative-index-insulator (INI)6, 11, insulator-metal-insulator (IMI)12 and metal-insulator-metal (MIM) waveguide tapers13, 14, 15. However, each proposal has its inherent difficulties resulting in the limited experimental realization of the rainbow trapping structures. For example, in our previous experimental reports, white light surface plasmon polariton (SPP) modes were launched into the on-chip gratings through nanoslits9, 10, leading to a very weak total coupling efficiency. For INI waveguide tapers, there is currently no clear pathway for realizing materials with negative refractive indices over a broad spectral range6. In a recent theoretical investigation, the rainbow trapping performance of INI, IMI and MIM waveguide tapers were analyzed and compared15.

It was concluded that the MIM structure can trap the first order (and higher order) transverse magnetic (TM) modes which makes them the best practical candidate for rainbow trapping among the three tapered waveguide structures (i.e. INI, IMI and MIM). However, even for the MIM structure, there are theoretical constraints to achieve the rainbow trapping conditions15. Consequently, trapped “rainbow” schemes based on INI, IMI or MIM waveguide tapers remain largely in the theoretical domain due to intrinsic constraints and difficulties in fabrication. In this Letter, we propose a hyperbolic metamaterial (HMM) structure to realize a highly efficient rainbow trapping effect in the vertical direction, which, importantly, is not limited by those severe theoretical constraints required by INI, IMI and MIM waveguide tapers, and therefore representing a significant promise to realize the rainbow trapping structure practically. This vertical HMM design is amenable to large area nanofabrication technologies, and will enable applications based on efficient rainbow trapping including photon harvesting and enhanced on-chip light-matter interactions.

HMM is referred to an artificial medium with subwavelength features whose iso-frequency surface is a hyperboloiod ...



http://www.nature.com/srep/2013/130213/ ... 01249.html
seasmith
 
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Re: Extraordinary Light

Unread postby seasmith » Fri Mar 01, 2013 7:41 pm

~
Light and Crystals


A new, up to date unknown aspect of the interplay between light and matter has now been examined
by a team of scientists at the Max Planck Institute of Quantum Optics (MPQ), the Technischen Universität München (TUM), the Fritz-Haber Institute in Berlin (FHI) and the Universität Kassel
using intensive ultraviolet laser pulses with only a few femtoseconds duration (one femtosecond is a millionth of a billionth of a second).



The continuous interplay between the positions of the atomic cores and the valence electrons determines the material characteristics such as electric conductivity, optical properties or the crystal lattice structure.

Following the first, intense laser pulse, the changes in the reflectivity of the crystal on the femtosecond timescale were observed by a second, weak light pulse. This measurement provides the scientists with information on the changes in the crystal induced by the first laser pulse [probe > sample]:
the intense ultraviolet laser pulse did not only heat up the valence electrons but also changed the electron distribution within the lattice. The electron density was reduced around the oxygen atoms and increased around the titanium atoms. This redistribution of the electrons causes a shift of the equilibrium position of the oxygen atoms relative to the titanium atoms,
which leads to an oscillatory motion of the oxygen atoms around the new equilibrium position.
...
In an intuitive picture the oxygen atoms in the crystal potential surface can be compared to a ball in a bowl. In the ground state, the ball is at rest at the center of the bowl. The excitation of the electrons corresponds to a sudden shift of the bowl, and the ball oscillates around its new minimum position.



... the scientists also observed a suprising effect:
after the excitation with the laser pulse, the electrons cool down to room temperature within about 20 femtoseconds, while the crystal is only heated slightly on these timescales. The cooling of the electrons led to an additional significant change in the valence electron distribution [crystal geometry].
In consequence, the equilibrium position of the lattice was shifted even further from the initial position of the ground state. Such a dependence of the crystal structure on the electron temperature has long been predicted theoretically. Now it could be observed experimentally for the first time.


[rededit by op]


http://www.nanowerk.com/news2/newsid=29307.php?
seasmith
 
Posts: 2616
Joined: Thu Mar 27, 2008 6:59 pm

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