An international team of physicists, led by King Abdullah University of Science and Technology (KAUST), Saudi Arabia, has demonstrated that chaos can beat order - at least as far as light storage is concerned.
The researchers deformed mirrors in order to disrupt the regular light path in an optical cavity and, surprisingly, the resulting chaotic light paths allowed more light to be stored than with ordered paths.
The work has important applications for many branches of physics and technology, such as quantum optics and processing optical signals over the Internet, where light needs to be stored for short periods to facilitate logical operations and to enhance light-matter interactions. Solar cells may also benefit, as trapping more light in them improves their ability to generate electricity.
The research, which is reported in Nature Photonics, involved a study of optical cavities - also known as optical resonators - and their ability to store light. Optical cavities typically store light by bouncing it many times between sets of suitable mirrors.
The researchers demonstrated a six-fold increase of the energy stored inside a chaotic cavity in comparison to a classical counterpart of the same volume.
The project, which involved researchers from the Universities of York and St. Andrews, as well as Bologna University, Italy, was initiated by Professor Andrea Fratalocchi from KAUST, Saudi Arabia, who also developed the theory behind chaotic energy harvesting.
Professor Fratalocchi said: "Chaos, disorder and unpredictability are ubiquitous phenomena that pervade our existence and are the result of the billionaire evolution of Nature. The majority of our systems try to avoid these effects, as a common think is that they diminish the performances of existing devices. The point of my research, conversely, is to show that disorder can be used as a building block for a novel, low-cost and scalable technology that outperforms by orders of magnitude current systems."
Professor Krauss, who moved to York from the University of St. Andrews last year, added: "Our results also have real-world practical implications. The cost of many semiconductor devices, such as LEDs and solar cells, is determined to a significant extent by the cost of the material. We show that the functionality of a given geometry, here exemplified by the energy that can be trapped in the system, can be enhanced up to six-fold by changing the shape alone, i.e. without increasing the amount of material and without increasing the material costs."
The study was enabled by funds made available from KAUST, through Prof. Fratalocchi's Research Grant "Optic s and Plasmonics for efficient energy harvesting" (Award No. CRG-1-2012-FRA-005), the UK Engineering and Physical Sciences Research Council (EPSRC), through the UK Silicon Photonics project and Dr. Di Falco's EPSRC Fellowship (EP/ I004602/1).