Directing Random Lasing Emission Using Cavity Exciton-Polaritons
Paul Bouteyre a, Hai Son Nguyen b, Jean-Sébastien Lauret a, Gaëlle Trippé-Allard a, Géraud Delport a, Ferdinand Lédée a, Hiba Diab a, Ali Belarouci b, Christian Seassal b, Damien Garrot c, Fabien Bretenaker a, Emmanuelle Deleporte a
a Laboratoire Aimé Cotton, CNRS, Univ. Paris-Sud, ENS Paris-Saclay, Université Paris- Saclay, 91405 Orsay Cedex, France
b Université de Lyon, Institut des Nanotechnologies de Lyon - INL, UMR CNRS 5270, CNRS, Ecole Centrale de Lyon, Ecully, F-69134, France
c Groupe d’Etude de la Matière Condensée, Université de Versailles Saint Quentin En Yvelines, Université Paris-Saclay, France, Avenue des États Unis, 45, Versailles, France
Oral, Paul Bouteyre, presentation 062
Publication date: 25th November 2019

Since a couple of years, the halide perovskites CH3NH3PbX3, with X a halogen (I, Br, Cl), have emerged in the framework of photovoltaics and of light-emitting devices such as electroluminescent diodes and lasers. These materials can be solution-processed at low temperature and their emission wavelength can be tuned over the entire visible spectrum via chemistry substitutions. In particular, the halide perovskites could address the "green gap" problem in laser sources, i.e. the drop in efficiency of solid-state LEDs and laser diodes emitting green light.

We consider here a one-dimensional planar microcavity containing a large-surface (1 cm2) spin-coated polycrystalline thin film of the green-emitting CH3NH3PbBr3 perovskite, in which the strong coupling regime at room temperature between the photon mode of the Fabry-Perot cavity and the perovskite excitonic mode was previously demonstrated [1]. The exciton-polaritons, which are a linear and coherent superposition of the exciton and photon states, arise from the strong coupling regime.

Random lasing occurs in highly disordered gain media in which cavity feedback is replaced by multiple scattering. The multi-directionality and low coherence of random lasers can satisfy various applications such as speckle-free imaging. However, for typical laser applications, the directionality of the lasing devices is desired.

We demonstrate here a random lasing emission in the green occurring in the microcavity which is directionally filtered by the lower polariton dispersion curve. The angle of emission can be controlled by changing the microcavity detuning. Angles of emission as large as 22° have been experimentally obtained. This result is interesting from a fundamental point of view because it combines two intriguing physical phenomena: the cavity exciton-polariton and the random lasing. Moreover, the control of the random lasing emission direction is a crucial point for optoelectronic applications, such as LIDAR technology.

This work has been financially supported by National French Agency for Research, in the framework of the projects EMIPERO and POPEYE. The work of P. Bouteyre is supported by the Direction Générale de l’Armement (DGA).

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