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Room temperature polariton lasing and condensation effects in III-nitride microcavities
|Raphaël Butté , Jacques Levrat , Gabriel Christmann , Eric Feltin , Jean-François Carlin , Nicolas Grandjean|
Institute of Quantum Electronics and Photonics Ecole Polytechnique Federale de Lausanne, Lausanne CH-1015, Switzerland
The recent demonstration of room temperature (RT) polariton lasing in a bulk GaN microcavity (MC) has established the possibility to use nitride semiconductors for the realization of polariton-based devices. Indeed, those structures could be used as novel low threshold coherent light emitting sources or micro optical parametric amplifiers. Unfortunately, achieving an efficient electrical injection within a bulk GaN active region is difficult. As a result the realization of an electrically pumped polariton laser based on such bulk samples should reveal highly challenging. A way to push forward polariton-based devices consists in achieving a well-grounded RT strong coupling regime (SCR) and demonstrating nonlinear effects in quantum well (QW) MCs for which the realization of an electrically pumped device should be more realistic. This would add to the recent demonstration of GaAs-based polariton light-emitting diodes. In this context, we have recently developed a structure using a GaN/AlGaN multiple quantum well (MQW) active region which allowed the demonstration of the SCR at RT with a record vacuum Rabi splitting value for a semiconductor QW MC (~ 56meV).
Here we report on the emission properties of this type of MCs under nonresonant optical pumping. It will be shown that the samples exhibit a nonlinear emission threshold at RT while remaining in the SCR. Experimental results will be depicted within the picture of polariton lasing and prospects regarding the realization of an electrically pumped polariton laser will be given. The behavior of the nonlinear emission threshold versus polariton trap depth and temperature, leading to the polariton condensation phase diagram, as well as that of the polarization of the emitted light below and above threshold will also be discussed. For the sake of comparison, if time permits, these results will be connected to those obtained on “standard” vertical cavity surface emitting lasers using InGaN/GaN QWs as an active region.
Presentation: Invited oral at E-MRS Fall Meeting 2009, Symposium C, by Raphaël Butté
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-04-20 10:48 Revised: 2009-07-23 16:12