Towards Bose-Einstein Condensation of Semiconductor Excitons: The Biexciton Polarization Effect

Abstract

We theoretically predict a strong influence of stimulated exciton-exciton scattering on semiconductor luminescence. The stimulated scattering causes circularly polarized instead of unpolarized emission at the biexciton emission line in a degenerate gas of partly spin polarized excitons. The biexciton polarization effect increases with increasing exciton densities and decreasing temperatures and approaches almost unity in the ultimate case of Bose-Einstein condensation. Time- and polarization-resolved luminescence measurements evidence the biexciton polarization effect both in ZnSe and GaAs quantum wells.

Size-dependent chemical transformation, structural phase change, and optical properties of nanowires

“…Strong coupling of this light field results in the formation of composite quasiparticles with both electronic and photonic character known as exciton-polaritons [185, 186] and it is through this polaritonic coupling mechanism as well as effects such as giant exciton oscillator strength and superradiance effects [187, 188], that crystal sizes comparable to the optical wavelengths can result in material dispersion that is significantly different from that of macroscopic crystals [189]. Associated exciting physical phenomena such as slow light [190], low threshold polariton lasing [191] and Bose-Einstein condensation [192, 193] all motivate such studies.…”

Tailoring light–matter coupling in semiconductor and hybrid-plasmonic nanowires

“…Aside from providing a solid foundation for further studies of one-dimensional polariton systems, the above research directly benefits the development of numerous applications. Controlled crossing into the cavity polariton regime and formation of coherent oscillators in the solid-state bodes well for low-threshold polaritonic lasing [30] and Bose-Einstein condensation [28,128]. Additionally one may simply consider the benefits conferred from reduced group velocities: enhanced sensitivity in sensors [129], optical buffering [130], quantum optics [131].…”

“…Controlled crossing into the cavity polariton regime and formation of coherent oscillators in the solid-state bodes well for low-threshold polaritonic lasing[30] and Bose-Einstein condensation. [28, 128] Additionally one may simply consider the benefits conferred from reduced group velocities: enhanced sensitivity in sensors,[129] optical buffering,[130] quantum optics. [131] Among the various applications which benefit from the above, however, few have the potential for illustrating the utility of light-matter coupling enhancement in nanostructures as all-optical switching.…”

Variable Temperature Spectroscopy of As-Grown and Passivated CdS Nanowire Optical Waveguide Cavities

“…The polaritonic behavior is typically characterized by (time-resolved) photoluminescence, transmission, and reflection measurements. 13,14 These polaritonic effects hold promise for exciting physical phenomena such as slow light, 15 low threshold polariton lasing 16 and Bose-Einstein condensation 17,18 and are therefore worthwhile to pursue in the nanowire geometry.…”

“…This results in the formation of exciton−polaritons, which are a linear superposition of excitons and photons, resulting in reversible emission and absorption and the formation of anticrossing lower and upper polariton branches (LPB and UPB) in the energy-wavevector dispersion. The polaritonic behavior is typically characterized by (time-resolved) photoluminescence, transmission, and reflection measurements. , These polaritonic effects hold promise for exciting physical phenomena such as slow light, low threshold polariton lasing and Bose−Einstein condensation , and are therefore worthwhile to pursue in the nanowire geometry.…”