Large-scale nanoimprinted metasurfaces based on silicon photonic crystal slabs were produced and coated with a NaYF4:Yb3+/Er3+ upconversion nanoparticle (UCNP) layer. UCNPs on these metasurfaces yield a more than 500-fold enhanced upconversion emission compared to UCNPs on planar surfaces. It is also demonstrated how the optical response of the UCNPs can be used to estimate the local field energy in the coating layer. Optical simulations using the finite element method validate the experimental results and the calculated spatial three-dimensional field energy distribution helps us to understand the emission enhancement mechanism of the UCNPs closely attached to the metasurface. In addition, we analyzed the spectral shifts of the resonances for uncoated and coated metasurfaces and metasurfaces submerged in water to enable a prediction of the optimum layer thicknesses for different excitation wavelengths, paving the way to applications such as electromagnetic field sensors or bioassays.
Site-controlled growth of semiconductor quantum dots (QDs) represents a major advancement to achieve scalable quantum technology platforms. One immediate benefit is the deterministic integration of quantum emitters into optical microcavities. However, site-controlled growth of QDs is usually achieved at the cost of reduced optical quality. Here, we show that the buried-stressor growth technique enables the realization of high-quality site-controlled QDs with attractive optical and quantum optical properties. This is evidenced by performing excitation power dependent resonance fluorescence experiments at cryogenic temperatures showing QD emission linewidths down to 10 µeV. Resonant excitation leads to the observation of the Mollow triplet under CW excitation and enables coherent state preparation under pulsed excitation. Under resonant π-pulse excitation we observe clean single photon emission associated with g (2) (0) = 0.12 limited by non-ideal laser suppression.Quantum emitters are central objects in emerging quantum technologies 1 . Quantum communication, for instance, is based on single photons as information carriers 2 . While simple quantum key distribution can be implemented by strongly attenuated lasers, advanced schemes for long distance quantum communication require entanglement distribution which requires real quantum emitters with a non-classical photon statistics, high photon indistinguishably and high extraction efficiency 3 . Recent experiments have shown that self-assembled semiconductor quantum dots (QDs) are prime candidates to meet these requirements 4 . Moreover, in contrast to nonclassical light sources relying on spontaneous parametric down conversion 5 , QDs offer the great prospect of providing single photons on demand 4 . The down-side of growing QDs by self-assembly is randomness in position and emission energy. This is particularly problematic when it comes to device integration. As a result, in-situ lithography techniques were invented to circumvent this issue by pre-selecting suitable QDs from a large ensemble 6,7 . On the other hand, on-chip schemes for photonic computing are usually based on regular arrays of coupled single photon emitters, or on quantum emitters integrated into regular waveguides 8,9 .In order to facilitate scalable device concepts based on QDs, different schemes for their site-controlled growth have been developed. A prominent example applies arrays of etched nanoholes and inverted pyramids as nucleation centers for the localized growth of QDs 10-13 . This approach leads to excellent site-control of the QDs position and allows for the device integration of spatially aligned single QDs. However, tight site-control goes along with enhanced impact of defect centers and non-radiative recombination when the QDs form in close proximity to the etched nanoholes 14 . Indeed, there is a) Electronic mail: stephan.reitzenstein@physik.tu-berlin.de a general trade-off between site-selectivity and optical quality of site-controlled quantum dots (SCQDs) 15,16 . Other approaches ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.