image: Prof. Paul Eastham and Luisa Toledo Tude.
Credit: Trinity College Dublin
Physicists from Trinity College Dublin believe new insights into the behaviour of light may offer a new means of solving one of science’s oldest challenges – how to turn heat into useful energy.
Their theoretical leap forwards, which will now be tested in the lab, could influence the development of specialised devices that would ultimately increase the amount of energy we can capture from sunlight (and lamps and LEDs) and then repurpose to perform useful tasks.
The work, supported by funding from Research Ireland, has just been published in the international journal, Physical Review A.
When photons (particles of light) are trapped in microscopic optical devices, they can undergo a form of condensation, where they behave collectively rather than as independent particles. In practice this concentrates light energy into a small, intense beam of a single very pure colour, similar to the output of a laser.
This phenomenon has been seen in experiments, but only when the energy input is already in the concentrated form provided by a laser. Now though, thanks to the new theoretical analysis, the physicists think it can be achieved using input energy in a diffused form, like that readily provided by sunlight, lamps, or LEDs.
Paul Eastham, Naughton Associate Professor, School of Physics, Trinity, is the senior author of the study. He said: “We modelled the behaviour of devices which trap light in a small region of space and found that this behaviour is related to the general properties of heat engines: machines that convert disorganised energy, which us physicists call ‘heat’, into a useful form, which we call ‘work’.”
“In this way, the same laws that limit steam engines and power plants determine whether photons condense or not. Beyond the conceptual appeal of this work, we believe it could influence the development of optical devices which rely on channelling the flow of light energy at the quantum level, from solar cells to microscopic engines powered by radiation.”
Luísa Toledo Tude, School of Physics, Trinity, first author of the research, added: “The primary goal of such optical devices would be to produce ‘useful’ energy, which would come out as laser-like light. In relative terms this is easy to convert to other forms, and any applications would involve doing that. For example, it might be possible to combine such a device with solar cells to increase the amount of electrical energy they capture from sunlight.”
“Because the next step is to test the theory in a lab setting we must be cautious not to over-speculate at this point, but of course it is exciting to think this work may one day help us increase the amount of useful energy we can capture from light sources and then put to work to power the millions of things we need it for.”
Journal
Physical Review A