What They Say
A group from Stanford University has published a paper on April 23 in Nature Communications, that allows engineers to fine tune the frequencies of individual photons in a stream of light to create any desired mix of colours. Stanford gave a less technical view that we have extracted from in this article.
“The structure consists of a low-loss wire for light (the black line below) carrying a stream of photons that pass by like so many cars on a busy throughway. The photons then enter a series of rings (orange), like the off-ramps in a highway cloverleaf. Each ring has a modulator (EOM in green) that transforms the frequency of the passing photons – frequencies which our eyes see as color. There can be as many rings as necessary, and engineers can finely control the modulators to dial in the desired frequency transformation.
The color of a photon is determined by the frequency at which the photon resonates, which, in turn, is a factor of its wavelength. A red photon has a relatively slow frequency and a wavelength of about 650 nanometers. At the other end of the spectrum, blue light has a much faster frequency with a wavelength of about 450 nanometers.
A simple transformation might involve shifting a photon from a frequency of 500 nanometers to, say, 510 nanometers – or, as the human eye would register it, a change from cyan to green. The power of the Stanford team’s architecture is that it can perform these simple transformations, but also much more sophisticated ones with fine control.
To further explain, Shanui Fan (senior author & Stanford professor) offers an example of an incoming light stream comprised of 20% photons in the 500-nanometer range and 80% at 510 nanometers. Using this new device, an engineer could fine-tune that ratio to 73% at 500 nanometers and 27% at 510 nanometers, if so desired, all while preserving the total number of photons. Or the ratio could be 37% and 63%, for that matter. This ability to set the ratio is what makes this device new and promising. Moreover, in the quantum world, a single photon can have multiple colors. In that circumstance, the new device actually allows changing of the ratio of different colors for a single photon.”
What We Think
While this doesn’t seem to have an immediate application in displays, I know that many of our readers, like Ian Jenks of Smartkem, who I interviewed for the upcoming SID Display Week CEO forum, are “photon junkies”.
The link to the original paper in the article was broken and we couldn’t track it down. We’ve reached out to Stanford for an accurate one and will add it if we can get one.
I managed to find the article here. Having looked at it – it’s beyond my pay grade!! (BR)
Schematic of the new photonic device showing the external waveguide (black), the light-altering rings (orange) and frequency modulators (green). The spectrum on the top left represents the ratio of frequencies of incoming light. The spectrum at the right is the result of the frequency transformation implemented by the system. (Image credit: Courtesy of the Fan Lab)
