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A group of researchers from Austria have sent twisted beams of light across the rooftops of Vienna. It is the first time that twisted light has been transmitted over a large distance outdoors, and could enable researchers to take advantage of the significant data-carrying capacity of light in both classical and quantum communications. Although the data rate is not very high, it could offer a way to provide unhackable data links via space. Would provide an edge over terrestrial fibre optics?

So basically we can photograph light now. Not just detect photons but photograph LIGHT WAVES. Really clever setup BTW.

Nautral Light for Human Space Exploration

wow, that looks pretty real to me! I remember a presentation some time ago on difficulties with large scale LED lights for making directed light sources. I guess we can cross that off the list :)

Agata - have a look at this!

very nice! "For a start, the wires operate well as switches that by some measures compare well to field effect transistors. For example they allow a million times more current to flow when they are on compared with off when operating at a voltage of about 1.5 V. "[A light effect transistor] can replicate the basic switching function of the modern field effect transistor with competitive (and potentially improved) characteristics," say Marmon and co. But they wires also have entirely new capabilities. The device works as an optical amplifier and can also perform basic logic operations by using two or more laser beams rather than one. That's something a single field effect transistor cannot do."

any idea how the shine the light selectively to such small surfaces?

"Illumination sources consisted of halogen light, 532.016, 441.6, and 325 nm lasers ported through a Horiba LabRAM HR800 confocal Raman system with an internal 632.8 nm laser. Due to limited probe spacing for electrical measurements, all illumination sources were focused through a 50x long working distance (LWD) objective lens (N.A. = 0.50), except 325 nm, which went through a 10x MPLAN objective lens (N.A. = 0.25)." Laser spot size calculated from optical diffraction formula 1.22*lambda/NA

"A light-emitting diode (LED) that emits more light energy than it consumes in electrical energy has been unveiled by researchers in the US. The device - which has a conventional efficiency of greater than 200% - behaves as a kind of optical heat pump that converts lattice vibrations into infrared photons, cooling its surroundings in the process."

Sorry, did not see that you have already posted this one ...

Mantis shrimp seem to have 12 types of photo-receptive sensors - but this does not really improve their ability to discriminate between colors. Speculation is that they serve as a form of pre-processing for visual information: the brain does not need to decode full color information from just a few channels which would would allow for a smaller brain. I guess technologically the two extremes of light detection would be RGB cameras which are like our eyes and offer good spatial resolution, and spectrometers which have a large amount of color channels but at the cost of spatial resolution. It seems the mantis shrimp uses something that is somewhere between RGB cameras and spectrometers. Could there be a use for this in space?

> RGB cameras which are like our eyes ...apart from the fact that the spectral response of the eyes is completely different from "RGB" cameras (http://en.wikipedia.org/wiki/File:Cones_SMJ2_E.svg) ... and that the eyes have 4 types of light-sensitive cells, not three (http://en.wikipedia.org/wiki/File:Cone-response.svg) ... and that, unlike cameras, human eye is precise only in a very narrow centre region (http://en.wikipedia.org/wiki/Fovea) ...hmm, apart from relying on tri-stimulus colour perception it seems human eyes are in fact completely different from "RGB cameras" :-) OK sorry for picking on this - that's just the colour science geek in me :-) Now seriously, on one hand the article abstract sounds very interesting, but on the other the statement "Why use 12 color channels when three or four are sufficient for fine color discrimination?" reveals so much ignorance to the very basics of colour science that I'm completely puzzled - in the end, it's a Science article so it should be reasonably scientifically sound, right? Pity I can't access full text... the interesting thing is that more channels mean more information and therefore should require *more* power to process - which is exactly opposite to their theory (as far as I can tell it from the abstract...). So the key is to understand *what* information about light these mantises are collecting and why - definitely it's not "colour" in the sense of human perceptual experience. But in any case - yes, spectrometry has its uses in space :-)

The first "molecules" made from two photons have been created by physicists in the US. The breakthrough could allow both conventional and quantum computers to encode and process information using photons.

I wonder if the effect also works with much larger numbers of photons involved. By slowing down any initial (Rydberg) photons and letting the later photons catch up it might be possible to create a very sharp "shock" front of photons. This could produce in itself be an ultra-short pulse of light or maybe it could be used as the trigger for massive stimulated emission in a laser.

Damn... At Leiden University I worked on transmission of light through Ag nano-layers. This could have been an easy experiment. I wonder about the evanescence of the wave as visible light is usually attenuated to <5% within 250nm of silver.

The solutions show light tied in knots

Really cool topic. Here a link to a paper from Leiden's quantum optics group from 2008 about knotted light (I was in that group at the time): http://www.nature.com/nphys/journal/v4/n9/abs/nphys1056.html

knot theory ... any volunteers?

Several recent papers on biomimetics and photonics, including works on structural colours, radiation shielding, spiders and more.

including one for Tom: Structural color and its interaction with other color-producing elements: perspectives from spiders Bor-Kai Hsiung ; Todd A. Blackledge ; Matthew D. Shawkey [+] Author Affiliations Proc. SPIE 9187, The Nature of Light: Light in Nature V, 91870B (September 8, 2014); doi:10.1117/12.2060831

UK researchers say they have achieved data transmission speeds of 10Gbit/s via "li-fi" - wireless internet connectivity using light. The researchers used a micro-LED light bulb to transmit 3.5Gbit/s via each of the three primary colours - red, green, blue - that make up white light. This means over 10Gbit/s is possible.

The unique structure and properties of graphene and the morphology of the bulk graphene material make it capable of not only absorbing light at various wavelengths but also emitting energetic electrons efficiently enough to drive the bulk material following Newtonian mechanics.

Hard to believe this should actually work, but would be quite a breakthrough indeed. I wonder, since the material should build up a significant electric potential over time, thus, pulling back the ejected electrons. Well, the paper apparently is not peer-reviewed, and I found some rather critical comments in some forums. Let's see if the experiment will be verified by another research team in due course.

That's really amazing. The problem is: driving drunk, too fast or without stopping at red traffic lights are the first causes of traffic fatalities, and finding a solution is really important... But those guys want to read our minds to see if there are

Light controller

Spectral dispersion of light on a finite-size surface plasmon polaritonic (SPP) crystal has been studied. The angular wavelength separation of one or more orders of magnitude higher than in other state-of-the-art wavelength-splitting devices available to

First demostration of coherent and reversible mapping of a light field with less than one photon per pulse onto an ensemble of approx10^7 atoms naturally trapped in a solid.

GaN in the future of lighting

Mitsubishi Heavy Industries said Friday that it has succeeded in transmitting 10 kW of power through 500 m. An announcement that comes just after JAXA scientists reported one more breakthrough in the quest for Space Solar Power Systems (http://phys.org/news/2015-03-japan-space-scientists-wireless-energy.html). One step closer to Power Generation from Space/

from the press release (https://www.mhi-global.com/news/story/1503121879.html) "10 kilowatts (kW) of power was sent from a transmitting unit by microwave. The reception of power was confirmed at a receiver unit located at a distance of 500 meters (m) away by the illumination of LED lights, using part of power transmitted". So 10kW of transmission to light a few efficient LED lights??? In a 2011 report (https://www.mhi-global.com/company/technology/review/pdf/e484/e484017.pdf), MHI estimated this would generate the same electricity output as a 400-megawatt thermal plant - or enough to serve more than 150,000 homes during peak hours. The price? The same as publicly supplied power, according to its calculations. There are no results to boost these claims however. The main work they do now is focused on beam steering control. I guess the real application in mind is more targeted to terrestrial applications, eg wireless highway charging (http://www.bbc.com/future/story/20120312-wireless-highway-to-charge-cars). With the distances so much shorter, leading to much smaller antenna's and rectenna's this makes much more sense to me to develop.