Photons lost in a maze
Enhancing the interaction between light and matter is the essence of many research disciplines, including quantum information science, energy harvesting and optical biosensing. The traditional method has been to strongly confine light in, for example, a highly ordered nanocavity. Surprisingly, an alternative approach to confinement of waves exists, originally proposed by Philip Anderson, and for which he was awarded the Nobel Prize in physics. Using this approach, disordered materials are employed, giving rise to random and multiple scattering of the propagating light waves. For a certain amount of randomness of the structures, so-called Anderson localized modes form spontaneously: light is trapped in a maze. A challenge in this research field has been to determine how well light can be confined based on random disorder. In a recent paper in New Journal of Physics researchers from The Quantum Photonics Group at DTU Fotonik have developed an efficient method for exciting Anderson-localized modes by embedding nanoscopic light sources (so-called quantum dots) inside the disordered material. By analyzing the statistics of the emitted light, the quality and extent of light confinement can be extracted. Surprisingly, the subtle interplay between the amount of disorder and the underlying periodic structure of the system studied can be exploited to confine light very efficiently, proving the potential of employing disorder for enchancement of light–matter interaction.