Polarization-resolved strong light–matter coupling in planar GaAs/AlGaAs waveguides

We study the influence of optical selection rules and polarization splittings on properties of exciton polaritons in a planar AlGaAs waveguide containing embedded GaAs quantum wells. We demonstrate that transverse electric and transverse magnetic modes couple differently with light- and heavy-hole quantum well excitons, which leads to distinct polarization splittings of the resulting polariton modes. The experimental data are in good agreement with modeling based on theoretical data for the optical selection rules for quantum well excitons

Nonlinear polaritons in a monolayer semiconductor coupled to optical bound states in the continuum

Optical bound states in the continuum (BICs) provide a way to engineer very narrow resonances in photonic crystals. The extended interaction time in these systems is particularly promising for the enhancement of nonlinear optical processes and the development of the next generation of active optical devices. However, the achievable interaction strength is limited by the purely photonic character of optical BICs. Here, we mix the optical BIC in a photonic crystal slab with excitons in the atomically thin semiconductor MoSe2 to form nonlinear exciton-polaritons with a Rabi splitting of 27 meV, exhibiting large interaction-induced spectral blueshifts. The asymptotic BIC-like suppression of polariton radiation into the far field toward the BIC wavevector, in combination with effective reduction of the excitonic disorder through motional narrowing, results in small polariton linewidths below 3 meV. Together with a strongly wavevector-dependent Q-factor, this provides for the enhancement and control of polariton–polariton interactions and the resulting nonlinear optical effects, paving the way toward tuneable BIC-based polaritonic devices for sensing, lasing, and nonlinear optics

Socialist Decentralization in the Andes? Explorative Reflections on Radical Democracy and 21st Century Neo-Constitutionalism

In this study the processes of neo-constitutionalism and participatory democracy in Bolivia, Ecuador and Venezuela are analyzed. Since 2006, these three countries spearhead the alleged leftist transformation of Latin America and the 21st Century Socialism. How are ideas of radical democracy reflected in the new Andean constitutions and which are the likely challenges, tensions and contradictions regarding the implementation of these measures to enhance local popular participation and social inclusion of previously marginalized groups? Additionally, an aim of this essay is to applicate a relatively novel concept for the academic debate on political development in Latin America: socialist decentralization. Therefore, the study will offer a problematization of the theoretical debate on decentralization and radical participatory democracy in the three Andean countries. Furthermore, certain challenges for the participatory political projects around presidents Hugo Chávez, Evo Morales and Rafael Correa will be identified