1. Strong Coupling of Exciton-Polaritons in a Bulk GaN Planar Waveguide: Quantifying the Coupling Strength
- Author
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Thierry Guillet, Pierre Disseix, Blandine Alloing, Laetitia Doyennette, Edmond Cambril, Jesús Zúñiga-Pérez, M. Gromovyi, Stephanie Rennesson, G. Kreyder, F. Médard, Fabrice Semond, Joël Leymarie, Sophie Bouchoule, François Réveret, and Christelle Brimont
- Subjects
Coupling ,Physics ,Photon ,Condensed matter physics ,Exciton ,Physics::Optics ,General Physics and Astronomy ,02 engineering and technology ,Dielectric ,Exciton-polaritons ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,law ,Ellipsometry ,0103 physical sciences ,Polariton ,010306 general physics ,0210 nano-technology ,Waveguide - Abstract
We investigate the demonstration and quantification of the strong coupling between excitons and guided photons in a GaN slab waveguide. The dispersions of waveguide polaritons are measured from T = 6 to 300 K through gratings. They are carefully analyzed within four models based on different assumptions, in order to assess the strong-coupling regime. We prove that the guided photons and excitons are strongly coupled at all investigated temperatures, with a small (11%) dependence on the temperature. However, the values of the Rabi splitting strongly vary among the four models: the "coupled oscillator" model overestimates the coupling; the analytical "Elliott-Tanguy" model precisely describes the dielectric susceptibility of GaN near the excitonic transition, leading to a Rabi splitting equal to 82 ± 10 meV for fundamental transverse-electric mode; the experimental ellipsometry-based model leads to smaller values of 55 ± 6 meV. We evidence that, for waveguides including active layers with large oscillator strengths, as required for room-temperature polaritonic devices, a strong bending of the modes' dispersion is not necessarily the signature of the strong coupling, which requires for its reliable assessment a precise analysis of the material dielectric susceptibility.
- Published
- 2020