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Nanostructured ultraviolet (UV) light sources represent a growing research field in view of their potential applications in wearable optoelectronics or medical treatment devices. In this work, we report the demonstration of the first flexible UV-A light emitting diode (LED) based on AlGaN/GaN core–shell microwires. The device is based on a composite microwire/poly(dimethylsiloxane) (PDMS) membrane with flexible transparent electrodes. The electrode transparency in the UV range is optimized: namely, we demonstrate that single-walled carbon nanotube electrodes provide a stable electrical contact to the membrane with high transparency (70% at 350 nm). The flexible UV-A membrane demonstrating electroluminescence around 345 nm is further applied to excite Zn–Ir–BipyPDMS luminophores: the UV-A LED is combined with the elastic luminophore-containing membrane to produce a visible amber emission from 520 to 650 nm. The obtained results pave the way for flexible inorganic light-emitting diodes to be employed in sensing, detection of fluorescent labels, or light therapy.

Efficient second harmonic generation and broad-band photoluminescence from deeply subwavelength and nontoxic nanoparticles is essential for nanophotonic applications. Here, we explore nonlinear optical response from mesoporous Si/SiO2, SiO2, and Si nanoparticles, considering various fabrication and treatment procedures. We show that thermal annealing (including femtosecond laser treatment) of mesoporous Si/SiO2nanoparticles provides the transformation of Si phase from amorphous to crystalline, enhancing the second harmonic and nonlinear photoluminescent response. Notably, the SiO2mesoporous frame of the considered Si/SiO2nanoparticles plays a dual positive role for the nonlinear process: it stabilizes the Si material, and SiO2:OH−material has a second-order nonlinearity itself and impacts to the observed second harmonic signal.

In this work we investigate the Raman response of extremely strained gallium phosphide nanowires. We analyze new strain-induced spectral phenomena such as 2-fold and 3-fold phonon peak splitting which arise due to nontrivial internal electric field distribution coupled with inhomogeneous strain. We show that high bending strain acts as a probe allowing us to define the electric field distribution with deep subwavelength resolution using the corresponding changes of the Raman spectra. We investigate the nature of the localization with respect to nanowire diameter, excitation spot position, and light polarization, supporting the experiment with 3D numerical modeling. Based on our findings we propose a research tool allowing to precisely localize the electric field in a certain subwavelength region of the nanophotonic resonator.

A compact optical layout of a pulse shaper for strongly chirped laser pulses of nanosecond time scale exploiting a tilted chirped volume Bragg grating and a programmable spatial light modulator is proposed. The setup has a non-zero frequency dispersion; thus it may be used for stretching or compressing the pulse and controlling its shape simultaneously. The feasibility of spectral shaping with a resolution of 0.16 nm, corresponding to a time resolution of 150 ps, and a contrast ratio of 10^2 is demonstrated experimentally.

We propose a novel strategy to enhance optoelectrical properties of single-walled carbon nanotube (SWCNT) films for transparent electrode applications by film patterning. First, we theoretically considered the effect of the conducting pattern geometry on the film quality factor and then experimentally examined the calculated structures. We extend these results to show that the best characteristics of patterned SWCNT films can be achieved using the combination of initial film properties: low transmittance and high conductivity. The proposed strategy allows the patterned layers of SWCNTs to outperform the widely used indium-tin-oxide electrodes on both flexible and rigid substrates.

Engineering of nonlinear optical response in nanostructures is one of the key topics in nanophotonics, as it allows for broad frequency conversion at the nanoscale. Nevertheless, the application of the developed designs is limited by either high cost of their manufacturing or low conversion efficiencies. This paper reports on the efficient second-harmonic generation in a free-standing GaP nanowire array encapsulated in a polymer membrane. Light coupling with optical resonances and field confinement in the nanowires together with high nonlinearity of GaP material yield a strong second-harmonic signal and efficient near-infrared (800–1200 nm) to visible upconversion. The fabricated nanowire-based membranes demonstrate high flexibility and semitransparency for the incident infrared radiation, allowing utilizing them for infrared imaging, which can be easily integrated into different optical schemes without disturbing the visualized beam.

Reduction of the wavelength in on-chip light circuitry is critically important not only for the sake of keeping up with Moore’s law for photonics but also for reaching toward the spectral ranges of operation of emerging materials, such as atomically thin semiconductors, vacancy-based single-photon emitters, and quantum dots. This requires efficient and tunable light sources as well as compatible waveguide networks. For the first challenge, halide perovskites are prospective materials that enable cost-efficient fabrication of micro- and nanolasers. On the other hand, III–V semiconductor nanowires are optimal for guiding of visible light as they exhibit a high refractive index as well as excellent shape and crystalline quality beneficial for strong light confinement and long-range waveguiding. Here, we develop an integrated platform for visible light that comprises gallium phosphide (GaP) nanowires directly embedded into compact CsPbBr3-based light sources. In our devices, perovskite microcrystals support stable room-temperature lasing and broadband chemical tuning of the emission wavelength in the range of 530–680 nm, whereas GaP nanowaveguides support efficient outcoupling of light, its subwavelength (<200 nm) confinement, and long-range guiding over distances more than 20 μm. As a highlight of our approach, we demonstrate sequential transfer and conversion of light using an intermediate perovskite nanoparticle in a chain of GaP nanowaveguides.

Strain engineering is a powerful tool that allows tuning of the optical and electronic properties of the nanostructures, opening new pathways for the nanowire (NW)-based practical applications. We introduce a complex study of individual bent GaP NWs based on micro-Raman mapping. Numerical modeling of the mapping data is performed to analyze spatial features in the Raman signal collected from the tensed and compressed areas of the NW with high resolution. The analysis revealed removal of a degeneracy and spectral shift of the modes arising from the linear strain distribution across the NW. Strain-dependent behavior of the combined longitudinal and transverse acoustic (LA + TA) band for single NW under uniaxial stress is studied for the first time. We introduce the novel Raman-based deep-subwavelength technique for the investigation of the structural and optoelastic properties of the nanosized objects without the use of tip-enhanced effects.

Composite active elements (AEs) of thin-disk geometry with an anti-amplified-spontaneous-emission (ASE) cap were created for the first time from dissimilar materials (Yb:YAG and sapphire crystals) using the surface-activated direct bonding method based on etching the surfaces with an Ar ion beam and then bringing them into optical contact. Using a sapphire anti-ASE cap allows the thermal lens optical power and the ${{\rm M}^2}$M^2 factor to be reduced significantly compared with the same AE with a YAG anti-ASE cap, and ${{\rm M}^2}$M^2 compared to standard Yb:YAG disks without an anti-ASE cap. Lasing with 320 W average power and ${\sim}{50}\% $∼50% slope efficiency was obtained.

The integration of direct bandgap III–V materials on Si is one of the main bottlenecks on the way to cheap and highly efficient optoelectronic devices. The goal of this work is to study the formation and optical properties of GaAs nanoparticles synthesized on Si(111) by molecular beam epitaxy. It is demonstrated that GaAs tends to grow in the shape of faceted nanoparticles surrounded by the continuous layer of coalesced GaAs islands. The surface density and shape of the nanoparticles are strongly affected by the growth parameters. The nanostructures are studied via analysis of atomic force microscopy images to show their faceting with the {111}, {110}, and {31̅1} planes. Optical properties are studied by photoluminescence and Raman spectroscopy. Depending on the growth conditions, Raman spectra of individual epitaxial GaAs nanoparticles possess specific features typical for wurtzite GaAs, demonstrating the potential of the studied growth approach for the synthesis of the phase engineered nanostructures.

III–V planar semiconductor heterostructures based on GaPN alloy with a nitrogen concentration up to 2.12% were grown on Si(001) by plasma assisted molecular beam epitaxy. Dependence of nitrogen incorporation on the growth conditions and its effect on the crystal structure were investigated via analysis of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy data. Continuous redshift and a substantial increase in intensity of the photoluminescence emission spectra were observed upon increase of nitrogen content. The effect of antiphase disorder in GaP buffer on the GaPN epilayer properties was studied. It was found that antiphase boundaries, protruding from the GaP/Si to the GaPN/GaP heterointerface, change their orientation and self-annihilate in the dilute nitride layer even with a low (0.5%) nitrogen content.

In this paper, we study light emission from a tunnel contact between the Au film on a glass substrate and the Au-coated tungsten probe of the scanning tunneling microscope at ambient conditions. We investigate the dependence of the intensity of the collected optical signal on the film surface morphology, namely, on geometrical parameters of nanometer-scale gold grains (islands) constituting the film. We reveal that the magnitude of inelastic tunnel current and thus photon emission intensity increase both with the decrease of island height and the increase of island width. We show that the difference in the optical emission intensity could reach 4 orders of magnitude for poly- and monocrystalline (atomically flat) samples. The observed phenomena are explained with dependence of the effective area of a tunnel contact on the grain aspect ratio. The obtained results demonstrate the crucial role of the sample morphology in influencing the efficiency of photon emission from the tunnel junction.

We combine the field confinement of plasmonics with the flexibility of multiple Mie resonances by bottom-up assembly of hybrid metal-dielectric nanodimers. We investigate the electromagnetic coupling between nanoparticles in heterodimers consisting of gold and barium titanate (BaTiO3or BTO) nanoparticles through nonlinear second-harmonic spectroscopy and polarimetry. The overlap of the localized surface plasmon resonant dipole mode of the gold nanoparticle with the dipole and higher-order Mie resonant modes in the BTO nanoparticle lead to the formation of hybridized modes in the visible spectral range. We employ the pick-and-place technique to construct the hybrid nanodimers with controlled diameters by positioning the nanoparticles of different types next to each other under a scanning electron microscope. Through linear scattering spectroscopy, we observe the formation of hybrid modes in the nanodimers. We show that the modes can be directly accessed by measuring the dependence of the second-harmonic generation (SHG) signal on the polarization and wavelength of the pump. We reveal both experimentally and theoretically that the hybridization of plasmonic and Mie-resonant modes leads to a strong reshaping of the SHG polarization dependence in the nanodimers, which depends on the pump wavelength. We compare the SHG signal of each hybrid nanodimer with the SHG signal of single BTO nanoparticles to estimate the enhancement factor due to the resonant mode coupling within the nanodimers. We report up to 2 orders of magnitude for the SHG signal enhancement compared with isolated BTO nanoparticles.

AbstractThe eXawatt Center for Extreme Light Studies project aimed to create a large scientific infrastructure based on lasers with giant peak power. The project relies on the significant progress achieved in the last decade. The planned infrastructure will incorporate a unique light source with a pulse power of 600 PW using optical parametric chirped pulse amplification in large-aperture KD2PO4, deuterated potassium dihydrogen phosphate crystals. The interaction of such laser radiation with matter represents a completely new fundamental physics. The direct study of the space–time structure of vacuums and other unknown phenomena at the frontier of high-energy physics and the physics of superstrong fields will be challenged. Expected applications will include the development of compact particle accelerators, the generation of ultrashort pulses of hard X-ray and gamma radiation for material science enabling one to probe material samples with unprecedented spatial and temporal resolution, the development of new radiation and particle sources, etc. The paper is translation from Russian [Kvantovaya Elektronika 53, 95 (2023)].

The concept of a high-power thin-rod Yb:YAG laser amplifier with high-brightness diode pumping was proposed. The principle of the amplifier parameter variation aimed at achieving an efficient signal gain at different power levels was developed. Three versions of thin-rod gain modules were implemented, where small and strong signal gains were studied experimentally. The ultrafast laser system with high average power (28 W) and high pulse energy (2.5 mJ) was created on the basis of the unique thin-rod gain modules.

Two multi-pass optical schemes of a disk laser amplifier have been proposed. Different variants of both the schemes with the smallest amount of optical elements and a lens in the active element taken into account have been calculated. For 64 passes of radiation through the active element, the average power of ∼50  W with ∼10% optical-to-optical efficiency in a pulse-periodic regime with a repetition rate of 10 kHz and a pulse duration of 2 ns was obtained at the amplifier output. The small signal gain amounted to 200.

This work presents a new design for the laser gain module based on a ytterbium-doped yttrium aluminum garnet (Yb:YAG) single-crystal thin rod. Thermal effects (temperature, phase, and polarization distortion of laser radiation) and small signal gain are investigated both experimentally and theoretically. We then analyzed the influence of thermal effects and amplified spontaneous emission on the power scaling of the laser based on the gain module. A small signal gain as high as 3.3 per pass was experimentally achieved.

Resonant semiconductor nanoparticles (NPs) that improve both light trapping and scattering have recently emerged as an additional tool for enhancing the efficiency of perovskite solar cells. Among the various types of nanostructures, silicon NPs, which support Mie modes and have lower losses compared with metallic particles with plasmon resonances, exhibit the best improvement for standard methylammonium lead iodide (MAPbI3)‐based solar cells. Herein, not only the optical problem of solar cell optimization with silicon nanoantennas is studied, but also the effects related to charge carrier transport in the presence of NPs are considered. In particular, it is theoretically shown that the silicon nanoantennas can be further optimized by p‐doping. The experimental verification is conducted for MAPbI3‐based solar cells by p‐doped silicon NPs in a hole transport layer (Spiro‐OMeTAD). The improved generation rate of charge carriers and hole transport through the doped silicon NPs leads to improved efficiency of the device. A novel approach for the improvement of a perovskite solar cell (PSC) is developed based on resonant nanoparticle incorporation into a hole transport layer of a n–i–p device. The PSC efficiency is increased up to 18.7% by Vocgrowth (1.07 V). Coupled optical and electrophysical calculations for PSC optimization with silicon nanoantennas are conducted for the first time.

Nano‐mechanical oscillator (NMO) based on amorphous carbon nanowhisker (CNW) with nanotraps for resonant weighting of nanoparticles in range of mass (10−14–10−15) g is presented. NMO with nanotraps is fabricated on the top of tungsten tip using focused electron beam technique. For resonant weighting the gold nanospheres are captured under the exposure of an electron beam by nanotraps locate on the top of CNW. Jump of gold nanoparticle to the nanotrap and oscillations of CNW are visualized using scanning electron microscope (SEM). The NMO amplitude‐frequency characteristics are calculated via automated numerical analysis of the sequence of SEM images obtained during the oscillations frequency sweeping. In order to calibrate the resonance mass detector based on CNW with nanotrap the gold nanosphere with diameter of (170 ± 5) nm and mass of (49.6 ± 9.2) × 10−15g is weighed in vacuum. The resonant mass detector (RMD) based on carbon nanowhiskerswith traps for weighing nanoobjects is presented. The carbon nanostructures are created using additive technique in a scanning electron microscope. Mechanical traps can reliably fix nanoparticles. It is shown that one can determine the mass of the nanoparticles with a sufficiently high accuracy in the range of (10−14–10−15) g using RMD.