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Superlattice switching from parametric instabilities in a driven-dissipative Bose-Einstein condensate in a cavity
摘要： We numerically obtain the full time-evolution of a parametrically driven-dissipative Bose-Einstein condensate in an optical cavity and investigate the implications of driving for the phase diagram. Beyond the normal and superradiant phases, a third nonequilibrium phase emerges as a many-body parametric resonance. This dynamical phase switches between two symmetry-broken superradiant configurations. The switching is accompanied by a substantial occupation of other momentum states not retained in the mapping to the Dicke model. The emergent phase shows features of nonintegrability and thermalization.
关键词： optical cavity,parametric resonance,Dicke model,thermalization,Bose-Einstein condensate
更新于2025-09-10 09:29:36
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Dynamic metasurface based cavity structures for enhanced absorption and phase modulation
摘要： Metasurface based optical cavity structures consist of a metallic metasurface realized on top of a dielectric slab backed with a metal plane. Such structures have been employed in the design of optical devices such as flat lenses, wave plates and holograms at frequencies from microwave to mid-infrared. Recently, such structures with dynamically reconfigurable optical characteristics have been explored for electrically tunable optical absorption and reflection phase modulation. To date, absorption modulation and phase modulation have been realized with large insertion loss. In this work, we employ an analytical approach based on transmission line theory where the metasurface is represented by a surface admittance. We extend the above approach for the design and analysis of under and over coupled resonance regimes in metasurface cavity structure. This enables a mutual design of cavity thickness and individual metasurface for large amplitude or phase modulation. A dynamic metasurface based optical cavity is experimentally demonstrated at THz frequencies where the dynamic metasurface consists of metallic resonators embedded with thin film vanadium dioxide patches. By driving insulator to metal transition in vanadium dioxide, the THz optical response of the metasurface based cavity structure is modulated. The fabricated device exhibits perfect absorption modulation and reflection phase modulation up to 180°. The reported results demonstrate the potential of such structures for realizing novel devices such as tunable holograms, high-efficiency modulators and frequency tunable filters at THz. The analytical approach presented here can be applied for analysis and design of metasurface cavity structures based on other material systems at frequencies ranging from THz to mid-infrared.
关键词： Terahertz,Phase modulator,Dynamic metasurface,Perfect absorption modulator,Metasurface optical cavity
更新于2025-09-10 09:29:36
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Stimulated Raman Scattering at Induced Acoustic Vibrations of Elastic Particles in Suspensions Placed in an Optical Cavity
摘要： The stimulated low-frequency Raman scattering at acoustic vibrations of elastic inclusions in a liquid heterogeneous medium placed in an external open optical cavity has been investigated. The amplitudes of stationary ?eld oscillations in the cavity at the frequencies of the excitation and the ?rst Stokes component are found within a two-dimensional model. The speci?c features of the oscillation in dependence of the parameters of the cavity and Raman-active medium have been studied based on the simulation results.
关键词： liquid heterogeneous medium,acoustic vibrations,elastic particles,optical cavity,stimulated Raman scattering
更新于2025-09-04 15:30:14