Theory of random lasing and light localization in strongly disordered media

• Applicant: Professor Dr. Johann Kroha
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2004 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5441996

In a random laser the feedback mechanism necessary for laser action is provided by the reduced diffusion and possibly confinement of light due to multiple random scattering in a strongly disordered, laser-active medium. In this project a theory for random lasers with coherent feedback is developed on a microscopic level, considering especially the possibility of light confinement due to Anderson localization of light. We construct a diagrammatic theory for the Anderson localization of light, incorporating both diffusion and Cooperon contributions by means of a controlled, selfconsistent resummation, and taking into account especially the modifications of the theory of light diffusion and localization due to the violation of particle number or energy conservation in an amplifying medium. The mutual interplay between light amplification, described by the semiclassical laser rate equations, and light confinement due to disorder is studied. We expect to provide quantitative predictions for possible pathways to the experimental realization of light localization either via band structure effects in disordered photonic band gap materials or via the consequences of coherent light amplification.

• DFG Programme: Research Grants