We present differential scanning calorimetry (DSC) analyses of seven French stained glasses from the 13th to 16th centuries. These glasses illustrate the dramatic compositional change from the antique soda‐rich glasses to potash‐ and lime‐rich compositions, resulting in drastic temperature and viscosity increases. We investigate the influence of chemical composition on glass thermal properties: glass‐transition (Tg), crystallization, and melting temperatures. We find that Tg varies from 533°C (soda type) to 638°C±17°C (potash type) to 685°C±5°C (lime type). The viscous slowdown of the melt as a function of the temperature, close to Tg, was modeled using the Vogel‐Tammann‐Fulcher equation. This enables temperature‐viscosity profile calculations, and suggests that recipes have been empirically optimized to reach similar thermoelastic properties suitable for glassmaking despite changing the nature of raw materials.
We experimentally demonstrate the possibility to modulate the second harmonic power emitted by nonlinear AlGaAs metasurfaces embedded in a liquid crystal (LC) matrix. This result is obtained by changing the relative in-plane orientation between the LC director and the linear polarization of the light at the excitation wavelength. According to numerical simulations, second-harmonic is efficiently radiated by the metasurfaces thanks to the sizeable second-order susceptibility of the material and the resonant excitation of either electric or magnetic dipole field distributions inside each meta-atom at the illuminating fundamental wavelength. This resonant behavior strongly depends on the geometric parameters, the crystallographic orientation, and the anisotropy of the metasurface, which can be optimized to modulate the emitted second harmonic power by about one order of magnitude. The devised hybrid platforms are therefore appealing in view of enabling the electrical control of flat nonlinear optical devices.
We model SPDC in dielectric nanoresonators based on quasinormal modes (QNMs). Using QNMs, the process reduces to a few interacting modes, providing intuition and enabling the design of nanoscale SPDC sources with complex functionalities.
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