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Investigation of spontaneous emission dynamics of dye molecules coupled into transverse Anderson localized cavities in a hyperbolic waveguide
摘要： Spontaneous emission dynamics of rhodamine 6G molecules coupled into transverse Anderson localized modes in a hyperbolic waveguide is investigated using time-resolved experiments. Four hyperbolic waveguides are simultaneously formed inside a deltoid-shaped fused-silica microtube via the capillary effect. The disordered photonic environment consisting of a rhodamine-doped polymeric material with randomly distributed air inclusions is attributed to localize photons at various resonant wavelengths of the quasi-optical cavities, randomly positioned throughout the guiding medium. The hyperbolic waveguides allow obtaining a single, double, and multimode resonant structures, trapping photons at various frequencies as explored in the form of sharp spectral resonances within the photoluminescence spectrum bandwidth of the dye molecules. Experimental results reveal that the coupling of the fluorescent emitters into multimode localizations in each hyperbolic waveguide corresponds to obtaining quasi-optical cavities at various resonant frequencies, which alter the emission characteristics of the emitters distinctively. The spontaneous emission rate of the dye molecules coupled into the isolated transverse Anderson localized modes is observed to increase by a factor of up to 6.7; thus, the vacuum fluctuations at certain resonant wavelengths are considerably enhanced.
关键词： Spontaneous emission,Transverse Anderson localization,Optical mode,Nano-cavity,Fluorescence lifetime
更新于2025-09-23 15:19:57
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Encounter of higher order exceptional singularities and towards cascaded state conversion
摘要： The appearance of topological singularities, namely exceptional points (EPs) is an intriguing feature of parameter-dependent open quantum or wave systems. EPs are the special type of non-Hermitian degeneracies where two (or more) eigenstates of the underlying system coalesce. In this paper, we present a three level non-Hermitian Hamiltonian which hosts three interacting eigenstates. The matrix elements are optimized in such a way that the intermediate eigenstate interacts with both the other states and the underlying system hosts at least two different second order EPs. This coupling scheme has proven to be highly effective to encounter higher order EPs. The impact of quasi-static parameter variation along a cyclic contour around the embedded EPs on the dynamics of interacting eigenvalues has been investigated comprehensively in the context of cascaded state conversion. Such dynamics of the eigenvalues show a clear signature of the third order EP. Moreover, we examine the accumulation of phases around the identified EPs and study the hallmark of phase exchange during cascaded state conversions accompanied by the parametric encirclement of the third order EP. A device level implementation of the scheme is possible exploiting multimode anisotropic waveguides or coupled waveguide systems.
关键词： Optical Mode Converters,Avoided Resonance Crossing,Higher Order Exceptional Point
更新于2025-09-19 17:15:36