Reconfigurable topological lasing through Thouless pumping in bilayer photonic crystal

Abstract: We propose a programmable photonic platform that integrates Thouless pumping and reconfigurable lasing in sliding bilayer photonic crystals. By engineering two periodic potentials -- a slowly moving photonic grating atop a stationary one -- we demonstrate how their interplay yields distinct topological phases characterized by either robust light transport (Thouless pumping) or localized spatial oscillation (trapping). A heterojunction between crystals in these two regimes supports an interface mode stemming from the topological phase transition across the boundary. This interface mode can be actively tuned via microelectromechanical systems or switched through the integration of phase-change materials. We further establish the feasibility of lasing action at this interface mode, offering a pathway toward topologically robust and reconfigurable lasers. Our findings provide a framework for exploring topological phase transitions and unify the fields of topological photonics and programmable photonic devices, opening avenues for multidimensionally tunable light sources.