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An easy and low-cost way to fabricate monometallic Au nanoislands for plasmonic enhanced spectroscopy is presented. The method is based on direct thermal evaporation of Au on glass substrates to form nanoislands, with thicknesses between 2 and 15 nm, which are subsequently covered by a thin layer of silicon dioxide. We have used HR-SEM and AFM to characterize the nanoislands, and their optical transmission reveals strong plasmon resonances in the visible. The plasmonic performance of the fabricated substrates has been tested in fluorescence and Raman scattering measurements of two probe materials. Enhancement factors up to 1.8 and 9×104 are reported for confocal fluorescence and Raman microscopies, respectively, which are comparable to others obtained by more elaborated fabrication procedures.

When synthetic dyes are used to embellish the world, the wastewater holding these hazardous materials is wantonly released into the biosphere. Appropriate treatment for such effluents is thereby indispensable. In this context, the present study was conducted to fabricate an eco-friendly, cost-effective and new bismuth modified silicon nanowires (Bi@SiNWs)-based photocatalysts toward superior photocatalytic degradation of methylene blue (MB) dye under both UV and solar irradiations. SiNWs were synthesized by silver-assisted chemical etching while Bi nanoparticles were anchored onto the NWs via thermal evaporation. By assessing the morphology, elemental composition, structure and crystallinity characteristics, these Bi@SiNWs nanocomposites are systematically identified. Extensive investigations of blank SiNWs and Bi@SiNWs optical properties — reflectance, transmittance, absorption coefficient, absorbance and optical band-gap — are presented. Near-perfect absorbance above 97%, over the visible wavelength region, has been achieved owing to the synergistic effect of Bi decoration on SiNWs. Accordingly, Bi@SiNWs showed remarkable photocatalytic ability for the degradation of MB up to 44% and 89% under UV and solar irradiation, respectively, only within 120 min. Repeated cycle runs revealed that the Bi@SiNWs composite photocatalyst exhibits strong reusability and photo-stability. Lastly, we will thoroughly provide the plausible mechanism for the photocatalytic degradation of MB over Bi@SiNWs. Our outcomes validate the potent role of Bi@SiNWs photocatalysts for effective environmental remediation.

La fotónica cuántica integrada es un elemento indispensable para para la miniaturización, estabilización y escalabilidad de las tecnologías cuánticas. El desarrollo de circuitos fotónicos integrados para aplicación en tecnologías cuánticas ayudará a traspasar el cuello de botella hacia niveles superiores de disponibilidad tecnológica y comercialización. La decoherencia cuántica supone uno de los retos técnicos a nivel fundamental con mayor relevancia para la realización de este desarrollo. En este contexto, el objetivo de este proyecto ha sido el de proporcionar herramientas teóricas para orientar la conceptualización y el diseño de los bloques fundamentales de los circuitos cuánticos integrados con vistas a la reducción de la decoherencia cuántica en estos sistemas. Los resultados obtenidos en forma de modelos teóricos, métodos numéricos de simulación y esquemas de optimización facilitan estas herramientas a través una serie de nuevos instrumentos matemáticos que sirven tanto para la caracterización de la decoherencia en diferentes componentes como para guías de diseño para su reducción: Expresiones analíticas que relacionan directamente los parámetros de diseño de estructuras fotónicas con el grado de decoherencia de la plataforma; Modelos para la simulación numérica de emisores cuánticos integrados en estructuras fotónicas que conectan la variación de los parámetros del diseño con el impacto en las figuras de mérito que caracterizan la decoherencia; Esquemas de optimización basados en métodos de Machine Learning para estructuras de fotónica cuántica integrada que ofrecen una reducción sin precedentes en términos de consumo de recursos computacionales; Interpretaciones físicas de las soluciones de los modelos desarrollados que contribuyen al avance del conocimiento del comportamiento de componentes de circuito en diferentes condiciones. El aparato matemático desarrollado ha sido evaluado a través de su aplicación en diferentes casos prácticos validando su fiabilid

Single photon sources (SPS) based on semiconductor quantum dot (QD) platforms are restricted to low temperature (T) operation due to the presence of strong dephasing processes. Although the integration of QD in optical cavities provides an enhancement of its emission properties, the technical requirements for maintaining high indistinguishability (I) at high T are still beyond the state of the art. Recently, new theoretical approaches have shown promising results by implementing two-dipole-coupled-emitter systems. Here, we propose a platform based on an optimized five-dipole-coupled-emitter system coupled to a cavity which enables perfect I at high T. Within our scheme the realization of perfect I single photon emission with dissipative QDs is possible using well established photonic platforms. For the optimization procedure we have developed a novel machine-learning approach which provides a significant computational-time reduction for high demanding optimization algorithms. Our strategy opens up interesting possibilities for the optimization of different photonic structures for quantum information applications, such as the reduction of quantum decoherence in clusters of coupled two-level quantum systems.

Temperature is one of the most relevant physical quantities that affects almost all processes in nature. However, the realization of accurate temperature standards using current temperature references, like the triple point of water, is difficult due to the requirements on material purity and stability of the environment. In addition, in harsh environments, current temperature sensors with electrical readout, like platinum resistors, are difficult to implement, urging the development of optical temperature sensors. In 2018, the European consortium Photoquant, consisting of metrological institutes and academic partners, started investigating new temperature standards for self-calibrated, embedded optomechanical sensor applications, as well as optimised high resolution and high re- liability photonic sensors, to measure temperature at the nano and meso-scales and as a possible replacement for the standard platinum resistant thermometers. This article presents an overview of the results obtained with sensor prototypes that exploit photonic and optomechanical techniques for sensing temperatures over a large temperature range (5 K to 300 K). Different concepts are demon- strated, including ring resonators, ladder-like resonators and suspended membrane optomechanical thermometers, highlighting initial performance and challenges, like self-heating that need to be overcome to realize photonic and optomechanical thermometry applications.

We demonstrate a dual-material integrated photonic thermometer, fabricated by high accuracy micro-transfer printing. A freestanding diamond micro-disk resonator is printed in close proximity to a gallium nitride on a sapphire racetrack resonator, and respective loaded Q factors of 9.1 × 104 and 2.9 × 104 are measured. We show that by using two independent wide-bandgap materials, tracking the thermally induced shifts in multiple resonances, and using optimized curve fitting tools the measurement error can be reduced to 9.2 mK. Finally, for the GaN, in a continuous acquisition measurement we record an improvement in minimum Allan variance, occurring at an averaging time four times greater than a comparative silicon device, indicating better performance over longer time scales.

One of the main steps towards large-scale quantum photonics consists of the integration of single photon sources (SPS) with photonic integrated circuits (PICs). For that purpose, the PICs should offer an efficient light coupling and a high preservation of the indistinguishability of photons. Therefore, optimization of the indistinguishability through waveguide design is especially relevant. In this work we have developed an analytical model that uses the Green's Dyadic of a 3D unbounded rectangular waveguide to calculate the coupling and the indistinguishability of an ideal point-source quantum emitter coupled to a photonic waveguide depending on its orientation and position. The model has been numerically evaluated through finite-difference time-domain (FDTD) simulations showing consistent results. The maximum coupling is achieved when the emitter is embedded in the center of the waveguide but somewhat surprisingly the maximum indistinguishability appears when the emitter is placed at the edge of the waveguide where the electric field is stronger due to the surface discontinuity.

A key requirement for the development of highly efficient silicon nanowires (SiNWs) for use in various kinds of cutting-edge applications is the outstanding passivation of their surfaces. In this vein, we report on a superior passivation of a SiNWs surface by bismuth nano-coating (BiNC) for the first time. A metal-assisted chemical etching technique was used to produce the SiNW arrays, while the BiNCs were anchored on the NWs through thermal evaporation. The systematic studies by Scanning Electron Microscopy (SEM), energy dispersive X-ray spectra (EDX), and Fourier Transform Infra-Red (FTIR) spectroscopies highlight the successful decoration of SiNWs by BiNC. The photoluminescence (PL) emission properties of the samples were studied in the visible and near-infrared (NIR) spectral range. Interestingly, nine-fold visible PL enhancement and NIR broadband emission were recorded for the Bi-modified SiNWs. To our best knowledge, this is the first observation of NIR luminescence from Bi-coated SiNWs (Bi@SiNWs), and thus sheds light on a new family of Bi-doped materials operating in the NIR and covering the important telecommunication wavelengths. Excellent anti-reflectance abilities of ~10% and 8% are observed for pure SiNWs and Bi@SiNWs, respectively, as compared to the Si wafer (50–90%). A large decrease in the recombination activities is also obtained from Bi@SiNWs heterostructures. The reasons behind the superior improvement of the Bi@SiNWs performance are discussed in detail. The findings demonstrate the effectiveness of Bi as a novel surface passivation coating, where Bi@SiNWs heterostructures are very promising and multifunctional for photovoltaics, optoelectronics, and telecommunications.

In this work, vertically aligned silicon nanowires (SiNWs) with relatively high crystallinity have been fabricated through a facile, reliable, and cost-effective metal assisted chemical etching method. After introducing an itemized elucidation of the fabrication process, the effect of varying etching time on morphological, structural, optical, and electrical properties of SiNWs was analysed. The NWs length increased with increasing etching time, whereas the wires filling ratio decreased. The broadband photoluminescence (PL) emission was originated from self-generated silicon nanocrystallites (SiNCs) and their size were derived through an analytical model. FTIR spectroscopy confirms that the PL deterioration for extended time is owing to the restriction of excitation volume and therefore reduction of effective light-emitting crystallites. These SiNWs are very effective in reducing the reflectance to 9–15% in comparison with Si wafer. I–V characteristics revealed that the rectifying behaviour and the diode parameters calculated from conventional thermionic emission and Cheung’s model depend on the geometry of SiNWs. We deduce that judicious control of etching time or otherwise SiNWs’ length is the key to ensure better optical and electrical properties of SiNWs. Our findings demonstrate that shorter SiNWs are much more optically and electrically active which is auspicious for the use in optoelectronic devices and solar cells applications.

La presente invención se refiere al uso de un material que comprende un recubrimiento capaz de reflejar luz de una longitud de onda de entre 350 nm y 850 nm, correspondientes a las regiones del espectro electromagnético del VIS, IR y UV, y un sustrato transparente a la luz VIS, para la fabricación de un cubreobjetos, un portamuestras o un recipiente de cultivo celular, particularmente un cubreobjetos, un portamuestras o un recipiente de cultivo celular que se utilizan en microscopía óptica.

The invention relates to the use of a material comprising a coating that can reflect light with a wavelength between 350 nm and 850 nm, corresponding to the VIS, IR and UV regions of the electromagnetic spectrum, and a substrate that is transparent to VIS light, for the production of a cover slip, a sample holder or a cell culture container, in particular a cover slip, a sample holder or a cell culture container used in light microscopy. [EN], La presente invención se refiere al uso de un material que comprende un recubrimiento capaz de reflejar luz de una longitud de onda de entre 350 nm y 850 nm, correspondientes a las regiones del espectro electromagnético del VIS, IR y UV, y un sustrato transparente a la luz VIS, para la fabricación de un cubreobjetos, un portamuestras o un recipiente de cultivo celular, particularmente un cubreobjetos, un portamuestras o un recipiente de cultivo celular que se utilizan en microscopía óptica. [ES]

We investigated the fabrication of large-area (cm2) nanostructured glasses for solar cell modules with hydrophobic and hydrophilic properties using soft lithography and colloidal lithography. Both of these techniques entail low-cost and ease of nanofabrication. We explored the use of simple 1D and 2D nanopatterns (nanowires and nanocones) and the effect of introducing disorder in the nanostructures. We observed an increase in the transmitted light for ordered nanostructures with a maximum value of 99% for wavelengths >600 nm when ordered nanocones are fabricated on the two sides of the solar glass. They produced an increment in the efficiency of the packaged solar cell with respect to the glass without nanostructures. On the one hand, the wettability properties showed that the ordering of the nanostructures improved the hydrophobicity of the solar glasses and increased their self-cleaning capacity. On the other hand, the disordered nanostructures improved the hydrophilic properties of solar glasses, increasing their anti-fogging capacity. The results show that by selecting the appropriate nanopattern, the wettability properties (hydrophobic or hydrophilic) can be easily improved without decreasing the efficiency of the solar cell underneath.

Soft lithography allows for the simple and low-cost fabrication of nanopatterns with different shapes and sizes over large areas. However, the resolution and the aspect ratio of the nanostructures fabricated by soft lithography are limited by the depth and the physical properties of the stamp. In this work, silicon nanobelts and nanostructures were achieved by combining soft nanolithography patterning with optimized reactive ion etching (RIE) in silicon. Using polymethylmethacrylate (PMMA) nanopatterned layers with thicknesses ranging between 14 and 50 nm, we obtained silicon nanobelts in areas of square centimeters with aspect ratios up to ~1.6 and linewidths of 225 nm. The soft lithographic process was assisted by a thin film of SiOx (less than 15 nm) used as a hard mask and RIE. This simple patterning method was also used to fabricate 2D nanostructures (nanopillars) with aspect ratios of ~2.7 and diameters of ~200 nm. We demonstrate that large areas patterned with silicon nanobelts exhibit a high reflectivity peak in the ultraviolet C (UVC) spectral region (280 nm) where some aminoacids and peptides have a strong absorption. We also demonstrated how to tailor the aspect ratio and the wettability of these photonic surfaces (contact angles ranging from 8.1 to 96.2°) by changing the RIE power applied during the fabrication process.

We have developed a low-cost, fast and sensitive plasmonic sensor with a large-size for easy handling. The sensor is formed by a Au nanobelt grating fabricated by soft lithography with a period of 780 nm and a width of 355 nm in an even and uniform area of ~2 × 2 cm2. The sensor uses the Fano-shaped third order mode localized plasmon resonance of the Au nanobelts, which appears in the visible part of the transmission spectrum. We have found a detection resolution of 1.56 × 10¿5 refractive index units with a temporal resolution of 1 s in a sensing area of 0.75 × 0.75 mm2. The high uniformity and size of the sensor permit the detection using a simple optical system, which provides the device with the potential to be used as an easy to handle, portable and disposable sensor.

The ultra-thin limit regime is characterized by a structure which at least in one dimension is significantly smaller than the incoming light wavelength. The absorption in this regime is characterized either by very weak absorption or by a broad peak attributed to the zeroth order Fabry-Perot mode. We show that this mode provides a 14.5% ultimate efficiency in a 25 nm GaAs slab on a gold substrate. GaAs in air achieves only a 5% for a 10 nm slab. Such an amplification of the resonance absorption is attributed to the high losses of the substrate. For very high losses, the zeroth order mode transits from an over-damped regime to an under-damped one.

The fabrication of a novel optofluidic chip using nanochannels optimized for DNA-stretched molecules and optical detection by enhanced fluorescence is reported. The chips are composed of a series of microchannels that allow the transport of molecules in the femto-liter per second inside a fluid or gas. The nanochannels are surrounded by a photonic crystal structure to enhance the emission of fluorescent light from the molecules, which can travel along the nanochannel, allowing for enhanced optical detection of the molecules in motion. The photonic crystal structure provides an enhancement up to 2.5 times in the light emitted from fluorescent molecules inside the nanochannels which increases to around 250 when normalized to the area of the nanochannels emitting fluorescence. The results may help to the detection of fluorescent molecules (like marked-DNA) in series by speeding it and allowing the use of less sophisticated equipment.