Yb3+-CsPbClxBr3−x perovskite nanocrystals with a high two-photon absorption cross-section of 2.3 × 105 GM embedded into amphiphilic silica microspheres emit visible and near-infrared light under two-photon infrared excitation in toluene and water.

Carbon dots (CDs) are promising nanostructures in the field of photonics owing to the ease of fabrication, tunable and efficient emission. Gallium phosphide (GaP) nanowires are known for high surface area, optical density, waveguiding, resonant optical properties but lacking the luminescence due to the indirect bandgap. Here, hybrid photonic structures - GaP nanowires decorated with the CDs are fabricated and studied. Feasible drop-casting deposition technique allows fabrication of dense vertical structures exhibiting efficient photoluminescence. Deposition of the CDs over the nanowires does not affect their luminescent properties demonstrating tolerance of the approach toward the surface aggregation. Tuning of the emission spectrum is obtained via variation of the excitation wavelength and CDs' synthesis protocol. The structures emitting throughout the visible range are obtained. Analysis of the photoluminescence of an individual structure demonstrates the most intense and fast recombination processes at the ends of a nanowire. It is shown that the luminescence of the CDs' covering a nanowire acting as a Fabry-Perot cavity is enhanced up to a factor of 3 governed by the Purcell effect. The obtained results unveil a path for fabrication of novel photonic devices via decoration of optically dense nanowires with CDs for enhanced and directed broadband emission.

Humans constantly interact with their environment, with other humans, as well as natural and artificial non-human agents. Nevertheless, our somatosensory system limits the diversity of our ways of communicating. Such organisms as plants thus escape our notice, blending into the landscape. This phenomenon is called Plant blindness. This leads not only to indifference and lack of empathy towards plants among ordinary people but also to a deficit in funding plant conservation. We believe that it is important to develop connections and also rethink the relationship between humans and flora. This paper examines the Plant turn in the context of an art-science project titled Plantoverse. The scientific part of the project is based on a study of plant epidermis cells, which possess optical properties and function as a “lens”. The data acquired via confocal microscopy was used to construct a mathematical model of these lenses which in turn formed the basis of the artistic work. It is a representation of the plant epidermis in a digital environment. The work allows us to look at ourselves through “plant optics'' and find new tools for interacting with the vegetal world. This interdisciplinary approach can help transfer knowledge about flora from the professional environment to lay society and form a new, more empathetic view toward plants.

Flexible transparent electrodes, encompassing the combination of optical transparency and electrical conductivity, empower numerous optoelectronic applications. While the main efforts nowadays concentrate on developing wire meshes and conductive oxides, those technologies are still in a quest to find a balance between price, performance, and versatility. Here we propose a new platform, encompassing the advantages of nanophotonic design and roll-to-roll large-scale lithography fabrication tools, granting an ultimate balance between optical, electrical, and mechanical properties. The design is based on an array of silica microspheres deposited on a patterned thin aluminum film attached to a flexible polymer matrix. Microspheres are designed to squeeze 80% light through nanoscale apertures with the aid of the photonic nanojet effect given the light impinges the structure from the top. The photonic structure blocks the transmission for the backpropagation direction thus granting the device with the high 5-fold level of asymmetry. The patterned layer demonstrates a remarkable 2.8 {\Omega}/sq sheet resistance comparable to that of a continuous metal layer. The high conductivity is shown to be maintained after a repeatable application of strain on the flexible electrode. The technical specifications of the demonstrated transparent electrode establish it as a viable option for integrating into advanced optoelectronic devices such as solar cells, touchscreens, and organic light-emitting diodes to name a few. Its notable capacity to optimize light transmittance while ensuring consistent electrical performance, alongside its mechanical flexibility, makes the demonstrated device an essential component for applications, where such attributes are critically required.

In this paper, we present the nonlinear damping identification method for the fast and comprehensive study of individual microparticles localized in a quadrupole electrodynamic Paul trap. The measurement procedure is discussed in detail. The size, mass and charge of individual silica microspheres from the studied sample are determined simultaneously and non-destructively. Experimental results agree well with the results of independent microscopic examination and density reference values. The further development of the method are outlined.

Composites based on nanomaterials are becoming more popular, especially for the creation of Förster Resonant Energy Transfer systems. Here, well-established zinc oxide tetrapods and a new carbon dot material were used to create a hybrid composite. The influence of the alkalinity of the medium on the formation of the composite was studied. The morphology and optical properties were studied in detail to confirm the formation of the composite. The measurement of photoluminescence lifetimes of carbon dots/zinc oxide tetrapods composites demonstrated nonradiative energy transfer. The efficiency of Förster Resonant Energy Transfer was theoretically calculated and the rate constants of this process, as well as reabsorption, were found. Consequently, the new composite based on carbon dots and zinc oxide tetrapods can find many applications, for example, in optical sensors.

The influence of ultraviolet (UV) laser irradiation on the optical properties of carbon dots (CDs) prepared by the hydrothermal synthesis from citric acid and ethylenediamine has been investigated. Investigation was performed in close-packed carbon films obtained by drop-casting. Observed photoluminescence redshift in films was ascribed to Forster Resonance Energy Transfer (FRET). UV laser irradiation increased carbon dot film light transmission and photoluminescence intensity and leads to a blueshift of photoluminescence. We attribute these changes to CD surface distraction via oxidation that leads to changing of FRET conditions. Controllable changing of carbon dot transmission and photoluminescence parameters by confocal laser irradiation might be used for optical microcoding and the creation of fluorescent labels.

Multifunctional nanocomposites that combine both magnetic and photoluminescent (PL) properties provide significant advantages for nanomedical applications. In this work, a one-stage synthesis of magneto-luminescent nanocomposites (MLNC) with subsequent stabilization is proposed. Microwave synthesis of magnetic carbon dots (M-CDs) was carried out using precursors of carbon dots and magnetic nanoparticles. The effect of stabilization on the morphological and optical properties of nanocomposites has been evaluated. Both types of nanocomposites demonstrate magnetic and PL properties simultaneously. The resulting MLNCs demonstrated excellent solubility in water, tunable PL with a quantum yield of up to 28%, high photostability, and good cytocompatibility. Meanwhile, confocal fluorescence imaging showed that M-CDs were localized in the cell nuclei. Consequently, the multifunctional nanocomposites M-CDs are promising candidates for bioimaging and therapy.

We report on the first, to the best of our knowledge, in-band pumped T m 3 + , H o 3 + codoped waveguide (WG) laser. A depressed-index surface channel WG (type III) with a 50 µm half-ring cladding is fabricated in a 5 at. % T m 3 + , 0.5 at. % H o 3 + : K L u ( W O 4 ) 2 crystal by femtosecond pulse direct laser writing. Under in-band pumping by a 1679 nm Er Raman fiber laser, T m 3 + and H o 3 + colasing is observed in the WG and explained by bidirectional energy transfer. The maximum total output power at ∼ 1942 n m ( T m 3 + ) and 2059 nm ( H o 3 + ) is 448 mW with a slope efficiencyM of 40.6%, which is a record high for this type of WG lasers. The maximum output power of the Ho laser reaches 144 mW.

Carbon dots have been modified using UV irradiation (405 nm laser light). UV irradiation of carbon dots has led to various changes in optical properties, which in turn means photomodification of the carbon dots surface. With an increase in light transmission, we have obtained the increasing intensity of photoluminescence and a blue shift by the laser irradiation of the carbon dots. The proposed method can help to adapt and improve the optical properties of carbon dots and can be used in applications, for example, in the optical encryption field.

Here we report on the development and investigation of a novel multiplex assay model based on polymer microspheres (PMS) encoded with ternary AIS/ZnS quantum dots (QDs). The system was prepared via layer-by-layer deposition technique. Our studies of Förster resonance energy transfer (FRET) between the QD-encoded microspheres and two different cyanine dyes have demonstrated that the QD photoluminescence (PL) quenching steadily increases with a decrease in the QD-dye distance. We have found that the sensitized dye PL intensity demonstrates a clear maximum at two double layers of polyelectrolytes between QDs and Dye molecules on the polymer microspheres. Time resolved PL measurements have shown that the PL lifetime decreases for the QDs and increases for the dyes due to FRET. The designed system makes it possible to record spectrally different bands of FRET-induced dye luminescence with different decay times and thereby allows for the multiplexing by wavelength and photoluminescence lifetimes of the dyes. We believe that PMS encoded with AIS/ZnS QDs have great potential for the development of new highly selective and sensitive sensor systems for multiplex analysis to detect cell lysates and body fluids' representative biomarkers.

Highly doped (20 at.%) Yb3+:LiYF4 single-crystalline thin films are grown on (001)-oriented bulk undoped LiYF4 substrates by Liquid Phase Epitaxy using lithium fluoride (LiF) as a solvent. The growth temperature lies around 741 degrees C (0.5-1 degrees C supercooling) and the growth rate is 1.8-2.6 gm/min. The single-crystalline nature of the films is confirmed by X-ray diffraction and polarized Raman spectroscopy. The film morphology is studied and discussed. The polarized spectroscopic properties of Yb3+ ions are reported, indicating a stimulated-emission crosssection of 0.88 x 10-20 cm2 at 993.9 nm in pi-polarization and a radiation trapping free lifetime of the 2F5/2 state of 2.00 ms indicating weak concentration-quenching. The crystal-field splitting of Yb3+ multiplets is resolved at 12 K. Highly-doped Yb3+:LiYF4/LiYF4 homoepitaxies are promising for waveguide and thin-disk lasers at -1 gm.

Исследована "распространенность" законов распределений на практике.Исследования проводились на основе энтропийного коэффициента для параметров различных объектов и процессов.Обоснована несостоятельность подхода, основанного на "тотальной" аппроксимации реальных законов распределений нормальным законом при проведении исследований и организации управления объектами различной природы.Учет изменчивости анализируемого параметра в виде величины энтропийного коэффициента реального закона распределения повышает адекватность описаний состояний неопределенности, что, в свою очередь, сказывается на эффективности исследований и принятия решений.В этом смысле весьма удобным и полезным инструментарием решения подобных задач являются методы и технологии теории энтропийных потенциалов.Возможности этой теории позволяют осуществлять мониторинг и организацию управления состояниями неопределенности сложных систем.Использование полученных данных позволяет оперативно оценивать доминирование конкретных

Surface channel waveguides (WGs) based on a half-ring (40-60-µm-diameter) depressed-index cladding (type III) geometry are fabricated in monoclinic Tm3+:MgWO4 by femtosecond (fs) laser writing at a repetition rate of 1 kHz. The WGs are characterized by confocal laser microscopy and μ-Raman spectroscopy. A Tm3+:MgWO4 WG laser generates 320 mW at ∼2.02µm with a slope efficiency of 64.4%. The WG emits a transverse single-mode and linear polarization (E||Nm). A remarkable low loss of <0.1dB/cm is measured for the WG. Vibronic laser emission at ∼2.08µm is also achieved.

Depressed-index buried and surface channel waveguides (type III) are produced in a bulk 3.5 at.% Tm3+:CALGO crystal by femtosecond direct-laser-writing at kHz repetition rate. The waveguides are characterized by confocal microscopy and µ-Raman spectroscopy. Under in-band-pumping at 1679 nm (3H6 → 3F4 transition) by a Raman fiber laser, the buried channel waveguide laser with a circular cladding (diameter: 60 µm) generated a continuous-wave output power of 0.81 W at 1866-1947 nm with a slope efficiency of 71.2% (versus the absorbed pump power) and showed a laser threshold of 200 mW. The waveguide propagation losses were as low as 0.3 ± 0.2 dB/cm. The laser performance under in-band pumping was superior compared pumping at ∼800 nm (3H6 → 3H4 transition), i.e., the convetional pump wavelength. Vibronic laser emission from the WG laser above 2 µm is also achieved. The low-loss behavior, the broadband emission properties and good power scaling capabilities indicate the suitability of Tm3+:CALGO waveguides for mode-locked laser operation at ∼2 µm.

Optical waveguides are the basic blocks of integrated photonic circuits due to their ability to confine light on the μm-scale. In particular, beam splitting waveguides, e.g., Y-branch splitters, are interesting as power splitters, directional couplers and interferometers with potential applications in bio- and environmental sensing [1]. One of the most powerful fabrication methods of 3D photonic microstructures is fs Direct Laser Writing (DLW). It features fast fabrication time, simplicity and variety of structures and materials including low-symmetry crystals. We present here the fabrication of laser-active Y-splitters in Tm-doped monoclinic crystals by fs-DLW and their characterization.

Depressed-index low-loss (0.38 dB/cm) buried channel waveguides with a circular cladding are fabricated in bulk Tm 3+ :SrF 2 by ultrafast laser inscription. The waveguide laser generated 148 mW at 1.87 μm with a slope efficiency of 63.9%.

We report the generation of mid-infrared (~2 µm) high repetition rate (MHz) sub-100 ns pulses in buried thulium-doped monoclinic double tungstate crystalline waveguide lasers using two-dimensional saturable absorber materials, graphene and MoS 2 .The waveguide (propagation losses of ~1 dB/cm) was micro-fabricated by means of ultrafast femtosecond laser writing.In the continuous-wave regime, the waveguide laser generated 247 mW at 1849.6 nm with a slope efficiency of 48.7%.The laser operated at the fundamental transverse mode with a linearly polarized output.With graphene as a saturable absorber, the pulse characteristics were 88 ns / 18 nJ (duration / energy) at a repetition rate of 1.39 MHz.Even shorter pulses of 66 ns were achieved with MoS 2 .Graphene and MoS 2 are therefore promising for high repetition rate nanosecond Q-switched infrared waveguide lasers.