Anderson localization of light and random lasing

• Applicant: Professor Dr. Georg Maret, since 6/2009
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2009 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 111328715

Anderson localization is among the most fundamental concepts in condensed matter physics.It describes the transition from diffusive transport to an insulating state of classical or quantumwaves due to constructive interference on closed multiple scattering paths solely with increasingdisorder. The transition to localization of light in three dimensional disordered systemshas only recently been observed experimentally by our group. For this, we have studied thetime resolved transmission of photons, which showed marked deviations from diffusive behavioursetting in at a critical value of disorder. Here, we propose to study the propertiesof the localization transition further by determining the light intensity fluctuations in samplesshowing Anderson localization. This should give a more definitive characterization of the localizedstates and will stimulate work in theory, where a treatment of the fluctuations in threedimensional localized samples has not yet been attempted.Furthermore, in the presence of a medium with gain in the scattering sample, the closedloops leading to Anderson localization may also act as lasing cavities. We therefore alsoplan to study the behaviour of localizing samples in the presence of an active medium anddetermine their properties as random lasers. For instance by characterizing the path length ofa lasing mode using time resolved transmission measurements, it will be possible to directlymeasure the extent of such a mode. Such measurements can clarify the question whether thenarrow modes observed in weakly scattering samples are truly random lasing modes.

• DFG Programme: Research Grants
• Major Instrumentation: CCD Camera ; Pulsed laser system
• Instrumentation Group: 5430 Hochgeschwindigkeits-Kameras (ab 100 Bilder/Sek) ; 5700 Festkörper-Laser
• Ehemaliger Antragsteller: Professor Dr. Christof Aegerter, until 6/2009