We study, both experimentally and theoretically, the modification of Er 3+ photoluminescence properties in Si dielectric nanoslots. The ultrathin nanoslot (down to 5-nm thickness), filled with Er in SiO 2 , boosts the electric and magnetic local density of states via coherent near-field interaction. We report an experimental 20-fold enhancement of the radiative decay rate with negligible losses. Moreover, via modifying the geometry of the all-dielectric nanoslot, the outcoupling of the emitted radiation to the far field can be strongly improved, without affecting the strong decay-rate enhancement given by the nanoslot structure. Indeed, for a periodic square array of slotted nanopillars an almost one-order-of-magnitude-higher Er 3+ PL intensity is measured with respect to the unpatterned structures. This has a direct impact on the design of more efficient CMOS-compatible light sources operating at telecom wavelengths.
Plasmonic nanostructures have been the object of strong scientific interest in the last decade for their linear and nonlinear optical properties. The present work is focused on the capability to control and enhance the Er 3þ emission efficiency in silica by near-field coupling with plasmonic and pre-plasmonic nanostructures. The results shows that more than one order of magnitude Er 3þ PL enhancement can be obtained with ultra-small pre-plasmonic Ag clusters synthesized by ion implantation and thermal annealing. Moreover, resonantly coupled extended plasmonic nanostructures in the form of gold nanohole arrays can efficiently interact with the Er ions, leading to a 20-fold increase of their radiative emission at 1.54 μm.
In the quest for new and increasingly efficient photon sources, the engineering of the photonic environment at the subwavelength scale is fundamental for controlling the properties of quantum emitters. A high refractive index particle can be exploited to enhance the optical properties of nearby emitters without decreasing their quantum efficiency, but the relatively modest Q-factors (Q ∼ 5− 10) limit the local density of optical states (LDOS) amplification achievable. On the other hand, ultrahigh Q-factors (up to Q ∼ 10 9 ) have been reported for quasi-BIC modes in all-dielectric nanostructures. In the present work, we demonstrate that the combination of quasi-BIC modes with high spectral confinement and nanogaps with spacial confinement in silicon slotted nanoantennas lead to a significant boosting of the electromagnetic LDOS in the optically active region of the nanoantenna array. We observe an enhancement of up to 3 orders of magnitude in the photoluminescence intensity and 2 orders of magnitude in the decay rate of the Er 3+ emission at room temperature and telecom wavelengths. Moreover, the nanoantenna directivity is increased, proving that strong beaming effects can be obtained when the emitted radiation couples to the high Q-factor modes. Finally, via tuning the nanoanntenna aspect ratio, a selective control of the Er 3+ electric and magnetic radiative transitions can be obtained, keeping the quantum efficiency almost unitary.
Non-interacting, disordered plasmonic nanodisk arrays have competitive performances for local and bulk sensing and a large stability basin around the maximum sensitivities.
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