102 research outputs found
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Controlled Modification of Erbium Lifetime by Near-Field Coupling to Metallic Films
Systematic measurements of the photoluminescence lifetime of the 1.54 μm transition of erbium implanted at different energies in SiO2 films with different metallic overlayers are reported. The lifetime shows a strong reduction up to a factor of 20 with decreasing distance between the erbium and the metal overlayer. The reduction of lifetime is mainly due to a near-field interaction between the erbium ions and the metal overlayers through generation of surface plasmon polaritons at the metal/SiO2 interface and direct generation of heat in the metal. These experiments combined with rigorous theoretical modeling demonstrate that a high degree of control over the radiative properties of erbium can be achieved in erbium-implanted materials in a wide range of implantation energies. The experiments also allow us to determine the radiative efficiency of erbium in bulk SiO2.Engineering and Applied Science
Thermally-Switchable Metalenses Based on Quasi-Bound States in the Continuum
Dynamic wavefront shaping with optical metasurfaces has presented a major
challenge and inspired a large number of highly elaborate solutions. Here, we
experimentally demonstrate thermo-optically reconfigurable, nonlocal
metasurfaces using simple device architectures and conventional CMOS-compatible
dielectric materials. These metasurfaces support quasi-bound states in the
continuum (q-BICs) derived from symmetry breaking and encoded with a spatially
varying geometric phase, such that they shape optical wavefront exclusively on
spectrally narrowband resonances. Due to the enhanced light-matter interaction
enabled by the resonant q-BICs, a slight variation of the refractive index
introduced by heating and cooling the entire device leads to a substantial
shift of the resonant wavelength and a subsequent change to the optical
wavefront associated with the resonance. We experimentally demonstrate a
metalens modulator, the focusing capability of which can be thermally turned on
and off, and reconfigurable metalenses, which can be thermo-optically switched
to produce two distinct focal patterns. Our devices offer a pathway to realize
reconfigurable, multifunctional meta-optics using established manufacturing
processes and widely available dielectric materials that are conventionally not
considered "active" materials due to their small thermo-optic or electro-optic
coefficients
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