RESUMEN
High refractive index dielectric nanoantennas strongly modify the decay rate via the Purcell effect through the design of radiative channels. Due to their dielectric nature, the field is mainly confined inside the nanostructure and in the gap, which is hard to probe with scanning probe techniques. Here we use single-molecule fluorescence lifetime imaging microscopy (smFLIM) to map the decay rate enhancement in dielectric GaP nanoantenna dimers with a median localization precision of 14 nm. We measure, in the gap of the nanoantenna, decay rates that are almost 30 times larger than on a glass substrate. By comparing experimental results with numerical simulations we show that this large enhancement is essentially radiative, contrary to the case of plasmonic nanoantennas, and therefore has great potential for applications such as quantum optics and biosensing.
RESUMEN
3D ceramic architectures are captivating geometrical features with an immense demand in optics. In this work, an additive manufacturing (AM) approach for printing alkaline-earth perovskite 3D microarchitectures is developed. The approach enables custom-made photoresists suited for two-photon lithography, permitting the production of alkaline-earth perovskite (BaZrO3 , CaZrO3 , and SrZrO3 ) 3D structures shaped in the form of octet-truss lattices, gyroids, or inspired architectures like sodalite zeolite, and C60 buckyballs with micrometric and nanometric feature sizes. Alkaline-earth perovskite morphological, structural, and chemical characteristics are studied. The optical properties of such perovskite architectures are investigated using cathodoluminescence and wide-field photoluminescence emission to estimate the lifetime rate and defects in BaZrO3 , CaZrO3 , and SrZrO3 . From a broad perspective, this AM methodology facilitates the production of 3D-structured mixed oxides. These findings are the first steps toward dimensionally refined high-refractive-index ceramics for micro-optics and other terrains like (photo/electro)catalysis.
RESUMEN
Ultrashort optical pulses are integral to probing various physical, chemical, and biological phenomena and feature in a whole host of applications, not least in data communications. Super- and subluminal pulse propagation and dispersion management (DM) are two of the greatest challenges in producing or counteracting modifications of ultrashort optical pulses when precise control over pulse characteristics is required. Progress in modern photonics toward integrated solutions and applications has intensified this need for greater control of ultrafast pulses in nanoscale dimensions. Metamaterials, with their unique ability to provide designed optical properties, offer a new avenue for temporal pulse engineering. Here an epsilon-near-zero metamaterial is employed, exhibiting strong nonlocal (spatial dispersion) effects, to temporally shape optical pulses. The authors experimentally demonstrate, over a wide bandwidth of tens of THz, the ability to switch from sub to superluminal and further to "backward" pulse propagation (±c/20) in the same metamaterial device by simply controlling the angle of illumination. Both the amplitude and phase of a 10 ps pulse can be controlled through DM in this subwavelength device. Shaping ultrashort optical pulses with metamaterials promises to be advantageous in laser physics, optical communications, imaging, and spectroscopy applications using both integrated and free-standing devices.
RESUMEN
Copper sulfide nanocrystals have recently been studied due to their metal-like behavior and strong plasmonic response, which make them an attractive material for nanophotonic applications in the near-infrared spectral range; however, the nature of the plasmonic response remains unclear. We have performed a combined experimental and theoretical study of the optical properties of copper sulfide colloidal nanocrystals and show that bulk CuS resembles a heavily doped p-type semiconductor with a very anisotropic energy band structure. As a consequence, CuS nanoparticles possess key properties of relevance to nanophotonics applications: they exhibit anisotropic plasmonic behavior in the infrared and support optical modes with hyperbolic dispersion in the 670-1050 nm spectral range. We also predict that the ohmic loss is low compared to conventional plasmonic materials such as noble metals in the NIR. The plasmonic resonances can be tuned by controlling the size and shape of the nanocrystals, providing a playground for future nanophotonic applications in the near-infrared.
RESUMEN
Metamaterials and metasurfaces provide unprecedented opportunities for designing light-matter interactions. Optical properties of hyperbolic metamaterials with meta-atoms based on plasmonic nanorods, important in nonlinear optics, sensing and spontaneous emission control, can be tuned by varying geometrical sizes and arrangement of the meta-atoms. At the same time the role of the shape of the meta-atoms forming the array has not been studied. We present the fabrication and optical characterization of metamaterials based on arrays of plasmonic nanocones closely packed at the subwavelength scale. The plasmonic mode structure of the individual nanocones and pronounced coupling effects between them provide multiple degrees of freedom to engineer both the field enhancement and the optical properties of the resulting metamaterials. The metamaterials are fabricated using a scalable manufacturing procedure, allowing mass-production at the centimeter scale. The ultra-sharp cone apex ([Formula: see text]2 nm) and the associated field enhancement provide an extremely high density of electromagnetic hot-spots (â¼1010 cm-2). These properties of nanocone-based metamaterials are important for the development of gradient-index metamaterials and in numerous applications in fluorescence enhancement, surface enhanced Raman spectroscopy as well as hot-carrier plasmonics and photocatalysis.