Playing laser light backwards could adjust data transmission signals so that they perfectly match receiving antennas. The fine-tuning of signals like this, not achieved with such detail before, could create more capacity for ever-increasing data demand.\n"Imagine, for example, that you could adjust a cell phone signal exactly the right way, so that it is perfectly absorbed by the antenna in your phone," says Stefan Rotter of the Institute for Theoretical Physics of Technische Universit\u00e4t Wien (TU Wien) in a press release.\nRotter is talking about \u201cRandom Anti-Laser,\u201d a project he has been a part of. The idea behind it is that if one could time-reverse a laser, then the laser (right now considered the best light source ever built) becomes the best available light absorber. Perfect absorption of a signal wave would mean that all of the data-carrying energy is absorbed by the receiving device, thus it becomes 100% efficient.\n\n\u201cThe easiest way to think about this process is in terms of a movie showing a conventional laser sending out laser light, which is played backwards,\u201d the TU Wein article says. The anti-laser is the exact opposite of the laser \u2014 instead of sending specific colors perfectly when energy is applied, it receives specific colors perfectly.\nPerfect absorption of a signal wave would mean that all of the data-carrying energy is absorbed by the receiving device, thus it becomes 100% efficient.\nCounter-intuitively, it\u2019s the random scattering of light in all directions that\u2019s behind the engineering. However, the Vienna, Austria, university group performs precise calculations on those scattering, splitting signals. That lets the researchers harness the light.\nHow the anti-laser technology works\u00a0\nThe microwave-based, experimental device the researchers have built in the lab to prove the idea doesn\u2019t just potentially apply to cell phones; wireless internet of things (IoT) devices would also get more data throughput. How it works: The device consists of an antenna-containing chamber encompassed by cylinders, all arranged haphazardly, the researchers explain. The cylinders distribute an elaborate, arbitrary wave pattern \u201csimilar to [throwing] stones in a puddle of water, at which water waves are deflected.\u201d\nMeasurements then take place to identify exactly how the signals return. The team involved, which also includes collaborators from the University of Nice, France, then \u201ccharacterize the random structure and calculate the wave front that is completely swallowed by the central antenna at the right absorption strength.\u201d Ninety-nine point eight percent is absorbed, making it remarkably and virtually perfect. Data throughput, range, and other variables thus improve.\nAchieving perfect antennas has been pretty much only theoretically possible for engineers to date. Reflected energy (RF back into the transmitter from antenna inefficiencies) has always been an issue in general. Reflections from surfaces, too, have been always been a problem.\n\u201cThink about a mobile phone signal that is reflected several times before it reaches your cell phone,\u201d Rotter says. It\u2019s not easy to get the tuning right \u2014 as the antennas\u2019 physical locations move, reflected surfaces become different.\nScattering lasers\nScattering, similar to that used in this project, is becoming more important in communications overall. \u201cWaves that are being scattered in a complex way are really all around us,\u201d the group says.\nAn example is random-lasers (which the group\u2019s anti-laser is based on) that unlike traditional lasers, do not use reflective surfaces but trap scattered light and then \u201cemit a very complicated, system-specific laser field when supplied with energy.\u201d The anti-random-laser developed by Rotter and his group simply reverses that in time:\n\u201cInstead of a light source that emits a specific wave depending on its random inner structure, it is also possible to build the perfect absorber.\u201d The anti-random-laser.