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This work was supported by the Ministry of Education and Science of the Russian Federation (project 16.8939.2017/8.9 for the section on devices) and Russian Science Foundation (project 17-73-20336 for the section on nanostructures). Y.K. acknowledges a support from the Strategic Fund of the Australian National University. A.Z. also acknowledges a partial support from the Welch Foundation (grant AT 16-17).

Direct laser reshaping of nanostructures is a cost-effective and fast approach to create or tune various designs for nanophotonics. However, the narrow range of required laser parameters along with the lack of in-situ temperature control during the nanostructure reshaping process limits its reproducibility and performance. Here, we present an approach for direct laser nanostructure reshaping with simultaneous temperature control. We employ thermally sensitive Raman spectroscopy during local laser melting of silicon pillar arrays prepared by self-assembly microsphere lithography. Our approach allows establishing the reshaping threshold of an individual nanostructure, resulting in clean laser processing without overheating of the surrounding area.

The propagation of focused femtosecond laser pulses with supercritical peak powers in air has been investigated by the methods of optical visualization, profilometry, and calorimetry. Laser pulses with supercritical powers create a bundle of submillimeter filaments with a diameter of about 5 µm ahead of the lens focus; the maximum number of filaments in the beam cross section and their length increase linearly and sublinearly, respectively, with the radiation peak power. The optical visualization and calorimetry indicate that the plasma channels of filaments are optical contrast (a plasma density of 1018–1019 cm−3), ensuring the refraction of laser radiation incident on them.

Both normal and abnormal sub-100-nanometer ripples (wavenumber ∼10 μm(-1)) were separately observed on Ti surfaces excited by linearly polarized IR femtosecond laser pulses at lower and higher fluences. Numerical modeling of dispersion curves for surface plasmon-polaritons on the photoexcited Ti surfaces demonstrates its surface plasmon resonance with the peak wavenumber ∼8 μm(-1) spectrally tuned by prompt surface optical response, prompt surface charging, and pre-oxidation, with normal/abnormal nanoripples appearing at its red/blue shoulders, respectively.

Ordered hybrid nanostructures for nanophotonics applications are fabricated by a novel approach via femtosecond laser melting of asymmetric metal-dielectric (Au/Si) nanoparticles created by lithographical methods. The approach allows selective reshaping of the metal components of the hybrid nanoparticles without affecting the dielectric ones and is applied for tuning of the scattering properties of the hybrid nanostructures in the visible range.

We propose a novel approach for efficient tuning of optical properties of a high refractive index subwavelength nanoparticle with a magnetic Mie-type resonance by means of femtosecond laser irradiation. This concept is based on ultrafast photoinjection of dense (10(20) cm(-3)) electron-hole plasma within such nanoparticle, drastically changing its transient dielectric permittivity. This allows manipulation by both electric and magnetic nanoparticle responses, resulting in dramatic changes of its scattering diagram and scattering cross section. We experimentally demonstrate 20% tuning of reflectance of a single silicon nanoparticle by femtosecond laser pulses with wavelength in the vicinity of the magnetic dipole resonance. Such a single-particle nanodevice enables designing of fast and ultracompact optical switchers and modulators.

We review a new, rapidly developing field of all-dielectric nanophotonics which allows to control both magnetic and electric response of structured matter by engineering the Mie resonances in high-index dielectric nanoparticles. We discuss optical properties of such dielectric nanoparticles, methods of their fabrication, and also recent advances in all-dielectric metadevices including couple-resonator dielectric waveguides, nanoantennas, and metasurfaces.

A novel method for single-step, lithography-free, and large-scale laser writing of nanoparticle-based plasmonic structures has been developed. Changing energy of femtosecond laser pulses and thickness of irradiated gold film, it is possible to vary diameter of the gold nanoparticles, while the distance between them can be varied by laser scanning parameters. This method has an advantage over the most previously demonstrated methods in its simplicity and versatility, while the quality of the structures is good enough for many applications.

In this work the formation of laser-induced periodic surface structures (LIPSS) on a titanium surface upon irradiation by linearly polarized femtosecond (fs) laser pulses with a repetition rate of 1 kHz in air environment was studied experimentally. In particular, the dependence of high-spatial-frequency-LIPSS (HSFL) characteristics on various laser parameters: fluence, pulse number, wavelength (800 nm and 400 nm), pulse duration (10 fs - 550 fs), and polarization was studied in detail. In comparison with low-spatial-frequency-LIPSS (LSFL), the HSFL emerge at a much lower fluence with orientation perpendicular to the ridges of the LSFL. It was observed that these two types of LIPSS demonstrate different fluence, shot number and wavelength dependencies, which suggest their origin is different. Therefore, the HSFL formation mechanism cannot be described by the widely accepted interference model developed for describing LSFL formation.

The reactivity of phthalonitrile, tetrafluorophthalonitrile and 4,5-dibutoxyphthalonitrile with unmodified surfaces of ZnO and SiO 2 and with the modified systems SiO 2/ Cp 2 Co , ZnO / Cp 2 Co , SiO 2/ Zn ( AcAc )2 prepared by deposition of cobaltocene ( Cp 2 Co ) and zinc acetylacetonate Zn ( AcAc )2, was studied ("in-situ-synthesis") in processes of phthalocyanine coatings. The formation of structural uniform phthalocyanines on carriers were established by UV-vis and mass spectra. The compounds were used then to compare their catalytic and photocatalytic activities in the oxidation of sulfide as a test reaction.

Plasmonic nanoparticles coupled with metallic films forming nanometer scale cavities have recently emerged as a powerful tool for enhancement of light-matter interaction. Despite high efficiency for sensing and light emission, such nanocavities exhibit harmful and uncontrolled optical heating which limits the ranges of light intensities and working temperature. In contrast to plasmonic nanoparticles, all-dielectric counterparts possess low Ohmic losses, high temperature stability along with a strong temperature-dependent Raman response. Here, we demonstrate that a silicon nanoparticle coupled with a thin gold film can serve as a multifunctional metal-dielectric (hybrid) nanocavity operating up to 1200 K. Resonant interaction of light with such nanocavity enables molecular sensing, heat-induced molecular events (protein unfolding), and their real-time tracing with a nanoscale thermometry through the monitoring enhanced Raman scattering both from the nanoparticle and analyzed molecules. We model numerically the thermo-optical properties of the hybrid nanocavity and reveal two alternative regimes of operation - with and without strong optical heating while other functionalities are preserved. We believe that the concept of the multifunctional hybrid nanocavities holds great potential for diverse photochemical and photophysical applications.

By using the laser printing technique, for the first time we fabricate spherical nanoparticles of germanium-antimony-telluride alloy possessing a high refractive index and amorphous-to-crystalline phase transition. The nanoparticles are examined by means of optical dark field micro-spectroscopy, which shows scatterers with different colours (with different optical resonances). The direct measurements of their diameters by using the transmission electron microscopy reveal that the nanoparticles' colours are related to different sizes of the nanoparticles. While most of nanoparticles are homogeneous, our study shows that some fabricated particles have a core-shell structure.

Hybrid halide perovskites have emerged as one of the most promising type of materials for thin-film photovoltaic and light-emitting devices. Further boosting their performance is critically important for commercialization. Here we use femtosecond laser for post-processing of organo-metalic perovskite (MAPbI3) films. The high throughput laser approaches include both ablative silicon nanoparticles integration and laser-induced annealing. By using these techniques, we achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally 10-fold enhancement of absorbance in a perovskite layer with the silicon nanoparticles. Direct laser annealing allows for increasing of photoluminescence over 130%, and increase absorbance over 300% in near-IR range. We believe that the developed approaches pave the way to novel scalable and highly effective designs of perovskite based devices.

Surface electromagnetic waves are characterized by the intrinsic spin-orbit interaction which results in the fascinating spin-momentum locking. Therefore, directional coupling of light to surface waves can be achieved through chiral nanoantennas. Here, we show that dielectric nanoantenna provides chiral response with strong spectral dependence due to the interference of electric and magnetic dipole momenta when placed in the vicinity of the metal-air interface. Remarkably, chiral behaviour in the proposed scheme does not require elliptical polarization of the pump beam or the geometric chirality of the nanoantenna. We show that the proposed ultracompact and simple dielectric nanoantenna allows for both directional launching of surface plasmon polaritons on a thin gold film and their demultiplexing with a high spectral resolution.

Interaction of light pulses of various durations and intensities with nanoscale photonic structures plays an important role in many applications of nanophotonics for high-density data storage, ultra-fast data processing, surface coloring and sensing. A design of optically tunable and reconfigurable structures made from different materials is based on many important physical effects and advances in material science, and it employs the resonant character of light interaction with nanostructures and strong field confinement at the nanoscale. Here we review the recent progress in physics of tunable and reconfigurable nanophotonic structures of different types. We start from low laser intensities that produce weak reversible changes in nanostructures, and then move to the discussion of non-reversible changes in photonic structures. We focus on three platforms based on metallic, dielectric and hybrid resonant photonic structures such as nanoantennas, nanoparticle oligomers and nanostructured metasurfaces. Main challenges and key advantages of each of the approaches focusing on applications in advanced photonic technologies are also discussed.

Silicon based micro- and nanophotonics yielding plenty of applications from black silicon for photovoltaics to all-dielectric nanoantennas for sensing and nonlinear optics requires advanced methods of fabrication. Here we provide a detailed investigation of femtosecond laser fabrication of silicon based miro- and nanostructures formed via self-organization processes revealing a strong influence of nonlinear optical feedback during their growth under multipulse irradiation. Our results are supported by the experimental study of the effects of laser wavelength, fluence, exposure time, and ambient gas pressure. We demonstrate that both sub-µm and µm-scale structures have similar principles of formation, which paves the way to controllable and low-cost fabrication of advanced optoelectronics devices with multilevel patterning of functional elements.

According to data, published by Cisco Company a volume of internet traffic increases constantly and this tendency reserves further. That is why the output of routers stays still an important factor, which influences the quality of services rendered by internet access providers, satisfying clients’ demands and, as a consequence, operators’ profit. Contained in the article results of routers comparison by firms Cisco, Juniper and Huawei affords us getting into distinctions between products of these firms and place an emphasis on their significant peculiarities.

We have demonstrated for the first time that an array of nanoantennas on an aluminum surface, fabricated using a double-pulse femtosecond laser irradiation scheme, results in a 28-fold enhancement of electron photoemission yield, driven by a third femtosecond laser pulse. The numerical electrodynamic modeling indicates that the electron emission is increased owing to instant local electromagnetic field enhancement near the nanoantenna, contributed by both the tip’s “lightning rod” effect and the focusing effect of the pit as a microreflector in parabolic nanoantenna.

A type of laser-induced surface relief nanostructure\char22{}the nanocrown\char22{}on thin metallic films was studied both experimentally and theoretically. The nanocrowns, representing a thin corrugated rim of resolidified melt and resembling well-known impact-induced water-crown splashes, were produced by single diffraction-limited nanosecond laser pulses on thin gold films of variable thickness on low-melting copper and high-melting tungsten substrates, providing different transient melting and adhesion conditions for these films. The proposed model of the nanocrown formation, based on a hydrodynamical (thermocapillary Marangoni) surface instability and described by a Kuramoto-Sivashinsky equation, envisions key steps of the nanocrown appearance and gives qualitative predictions of the acquired nanocrown parameters.

We have demonstrated for the first time that an array of nanoantennas (central nanotips inside sub-micron pits) on an aluminum surface, fabricated using a specific double-pulse femtosecond laser irradiation scheme, results in a 28-fold enhancement of the non-linear (three-photon) electron photoemission yield, driven by a third intense IR femtosecond laser pulse. The supporting numerical electrodynamic modeling indicates that the electron emission is increased not owing to a larger effective aluminum surface, but due to instant local electromagnetic field enhancement near the nanoantenna, contributed by both the tip's lightning rod effect and the focusing effect of the pit as a microreflector and annular edge as a plasmonic lens., 4 pages, 3 figures

Separate nanoholes with the minimum size down to 35 nm (∼λ/15) and nanohole arrays with the hole size about 100 nm (∼λ/5) were fabricated in a 50 nm optically “thick” Au/Pd film, using single 532 nm pump nanosecond laser pulses focused to diffraction-limited spots by a specially designed apertureless dielectric fiber probe. Nanohole fabrication in the metallic film was found to result from lateral heat diffusion and center-symmetrical lateral expulsion of the melt by its vapor recoil pressure. The optimized apertureless dielectric microprobe was demonstrated to enable laser fabrication of deep through nanoholes.

Here, the novel concept of asymmetric metal-dielectric (hybrid) nanoparticles is proposed. The experimental data and the results of numerical simulation of the optical properties of hybrid nanostructures are presented. The change of their optical response after fs- laser modification is shown. The possibility of manipulating Fano resonance in hybrid oligomers by the gold nanoparticles reshaping is demonstrated.

We propose a novel strategy for self-adjusted fabrication of large-scale array of resonant silicon nanoparticles (metasurface) on a thin silicon film. The self-adjusting mechanism is based on the effect of resonant nanogratings formation under intense multishot femtosecond irradiation of a thin silicon film. The resulting metasurfaces allow for generation of ultraviolet laser pulses at a wavelength of 270 nm with conversion efficiency up to 10-6 and high peak (≈100 kW/sm2) and average power (≈1.5 μW). Such high peak power from ultrathin metasurface makes the generated UV pulses applicable in a wide range of applications: precise nanolithography, ultrafast photoexcitation etc.

Hybrid nanophotonics based on metal-dielectric nanostructures unifies the advantages of plasmonics and all-dielectric nanophotonics providing strong localization of light, magnetic optical response and specifically designed scattering properties. Here, we propose a new method for optical properties tuning of hybrid dimer nanoantenas via laser-induced melting at the nanoscale. We demonstrate numerically that near- and farfield properties of a hybrid nanoantenna dramatically changes with fs-laser modification of Au particle. The results lay the groundwork for the fine-tuning of hybrid nanoantennas and can be applied for effective light manipulation at the nanoscale, as well as biomedical and energy applications.

We develop a novel method of core-shell nanoparticles fabrication based on laser ablation of multilayer thin films using femtosecond laser pulses. Transmission electron microscopy proves that the obtained structures have Si and Au separated parts. We theoretically show that the combination of high refractive index dielectric and plasmonic nanoparticles shows possibility of interplay between magnetic optical responses and plasmon resonances. This opens a possibility to manipulate by both scattering power pattern and local optical field enhancement via precise engineering of the core/shell nanoparticles.

The influence of femtosecond laser irradiation on the formation of an oxide layer on the surface of VT6 titanium alloy (Ti–6Al–4V) is studied. The structure, chemical and phase composition have been studied by x-ray diffraction, and scanning and transmission electron microscopy. The formation features of an oxide layer, which contains TiO2-rutile, TiO2-anatase Al2TiO5-aluminum titanate, Ti3O5-titanium oxide and TiO-titanium monoxide on the femtosecond laser-irradiation modified surface have been analyzed.

The single-shot spallation thresholds for copper and silver surfaces demonstrate a considerable IR-laser (1030 nm) pulse-width dependent increase over a range of 0.2–12 ps for the former material and a very weak increase for the latter one, while the corresponding thresholds for visible (515 nm) laser pulses remain almost constant. The IR-laser increase of the ablation thresholds is related to two-photon interband (d–s) absorption in copper, contrasting with the linear absorption of visible laser pulses in this material. In silver, common weakly sublinear dependences on the laser pulsewidth were observed, ruling out possible multi-photon—either three(four)-photon in IR, or two-photon in the visible range—interband transitions in this material. Moreover, electron-lattice thermalization times of 1–2 ps were evaluated for these materials in the spallative ablation regime, contrasting strongly with the previously theoretically predicted multi-picosecond thermalization times.

A novel method for single-step, lithography-free, and large-scale laser writing of arrays of metallic (Au) and semiconductor (Si) nanoparticles (nanoresonators) has been developed. Changing energy of femtosecond laser pulses and film thickness it is possible to vary diameter of the nanoparticles, while the distance between them can be varied by laser scanning parameters. This method has an advantage over the most previously demonstrated methods in its simplicity and versatility, while the quality of the structures is good enough for many applications.

High refractive index subwavelength dielectric nanoresonators, which support both electric and magnetic optical resonances, are a promising platform for many nanophotonic applications. However, the resonant properties of the nanoresonators are highly sensitive to defect concentrations. Therefore, to maintain low defect concentrations, it has generally thought inevitable to use crystalline precursor materials for nanoresonator fabrication. Here, we show that it is possible to fabricate crystalline (low-loss) resonant silicon nanoparticles by femtosecond laser ablation from amorphous (high-loss) silicon thin films. The crystallinity of the fabricated nanoparticles is proven by means of Raman spectroscopy and electron transmission microscopy, and their optical resonant properties are studied by means of dark-field optical spectroscopy and discrete-dipole simulations.

Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures (commonly reffered to as, laser induced periodic surface structures, LIPSS). The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments (Vacuum & O2) on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope (SEM). The ablation threshold with single and multiple (N = 100) shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the O2 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDS), respectively. SEM investigations reveal the formation of LIPSS (nano & micro). FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to O2. Furthermore, the O2 environment reduces the ablation threshold. XRD data reveal that for the O2 environment, new phases (oxides of Ti) are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element (Al) is reduced. The irradiation in the O2 environment results in 15% atomic diffusion of oxygen.

Two femtosecond laser nanograting fabrication mechanisms, including new ones recently found in our laboratory and related to sub-and near-threshold surface nanostructuring, are illustrated using experimental data for diverse solids nanostructured by 744-nm femtosecond laser pulses.

Dependences of absolute vapor/plasma pressure on femtosecond and nanosecond laser intensities were obtained for graphitic materials using a non-contact broadband ultrasonic technique, and propulsion prospects of femtosecond and nanosecond laser launching approaches are discussed.

Strong ablative shock waves were generated on a highly oriented pyrolytic graphite surface by intense IR femtosecond laser pulses in a broad fluence range and their basic parameters (pressure, velocity) were acquired by means of a non-contact broadband ultrasonic technique. At moderate laser fluences (F ≥ 0.3 J/cm2), ultrafast formation of a dense, strongly-heated (supercritical) carbon phase is expected, which expands on a fluence-dependent picosecond timescale in the form of a point-like three-dimensional explosion, driving a multi-GPa shock wave both in ambient air and the graphite target. At higher laser fluences (F > 5 J/cm2), critical electron-ion plasma is formed instantaneously during the exciting femtosecond laser pulse, with its strong plasma absorption initiating a TPa-level shock wave (the maximum shock wave pressure ≈ 3 TPa is more than twice the previous maximum for carbon). Because of the ablative removal of the laser-heated surface carbon layer, the following time-integrated structural studies indicate the formation of a mixture of diamond and graphite nanocrystallites or, in other words, glassy carbon only in the redeposition products.

The sub and near-threshold topographic signatures of the spallation of nanometer-thick melt layers during single-shot femtosecond laser ablation of bulk aluminum and gold were experimentally observed for the first time, using scanning electron microscopy with high spatial resolution. The novel ablative nanofeatures—sub-threshold boiling nanopits, the partially detached ultrathin solidified melt layer, and the lamellar surface structure under the layer along the spallative crater border, as well as the foam-like nanostructure of the crater bottom—indicate the boiling origin of the spallation threshold, rather than the thermomechanical rupture of the molten surface layer in a propagating unloading wave. These ablative surface nanofeatures were also revealed in trenches of single-shot, near-wavelength normal interference ripples on the aluminum surface, indicating their spallative nature and being promising for biosensing applications.

Superimposed one-dimensional quasiperiodic gratings with multiple periods \ensuremath{\Lambda} \ensuremath{\approx} 110--800 nm well below or comparable to the pump laser wavelength of 744 nm, and ridge orientations perpendicular to the linear polarization of infrared femtosecond laser pulses, were fabricated after multiple near-threshold laser shots on a planar surface of quasimonocrystalline graphite in ambient air. The broad range of the grating periods corresponds to the large number of spatial Fourier harmonics of the final nanorelief (up to $m=7$th order, ${\ensuremath{\Lambda}}_{m}\ensuremath{\approx}800$ nm/$m=110--800$ nm), qualitatively representing the nonsinusoidal profile of the laser-induced intermediate surface relief (the set of periodic, broadly spaced narrow nanotrenches), which provides the corresponding multiangle diffraction of the incident femtosecond laser pulses. Experimental measurements and modeling of the transient optical constants of the photoexcited graphite justify the excitation, at the first stage, of the first-order (${\ensuremath{\Lambda}}_{1}\ensuremath{\approx}800$ nm) surface plasmon-polaritonic (SPP) wave on the photo-excited initial planar graphite surface becoming metallic via photo-generation of dense electron hole plasma ($\ensuremath{\sim}{10}^{21}$ cm${}^{\ensuremath{-}3}$). Such an SPP wave provides intermediate nanorelief in the form of the nonsinusoidal surface grating via its interference with the incident laser wave, resulting under near-threshold laser irradiation conditions in the highly localized surface ablation of the material in the interference maxima. During the next stage, the multiperiod subwavelength nanogratings develop through the multiangle diffraction of the multiple incident laser pulses on the intermediate nonsinusoidal surface grating.

Fluence dependences of IR and UV reflectivity of femtosecond laser pulses on a HOPG surface demonstrate their saturation in a certain fluence range, starting from 0.2 J cm−2, where single-shot non-linear plasma emission is detected by electric probe measurements. This correlation between prompt solid-state optical/electronic dynamics and electron–ion plasma emission indicates prompt 'freezing' of surface electronic dynamics via its plasma-emission cooling and simultaneous ultrafast shallow laser ablation of the surface. Strong HOPG disordering is observed in Raman spectra for laser fluences, exceeding the plasma emission threshold.

In this work, we demonstrate an all-laser method of fabrication of optical nanoantennas (ONAs) with an additional coupling/focusing diffractive element. This method is based on double-shot femtosecond laser nanoablation of a thin supported metallic film, inducing a sequence of electrodynamic (surface plasmon-polariton [SPP] excitation and interference), thermal (melting, ablation and ultrafast cooling), and hydrodynamic processes. In particular, the thermal and hydrodynamic processes are important for ONA formation after the first laser shot, while second spatially shifted laser shot via an induced SPP wave results in a radial surface grating near the nanoantenna. Such gratings provide efficient coupling between incident laser radiation and SPP waves, thus significantly improving the ONA efficiency.

The interaction of slighly relativistic femtosecond laser radiation with microstructured Si targets was studied. The microstructuring was performed by nanosecond pulse laser ablation with additional chemical etching of the target material. An analysis was made of the optical damage under the action of femtosecond radiation near the ablation threshold. It was experimentally demonstrated that the hot electron temperature increases appreciably in the laser-driven plasma (from ~370 to almost 500 keV) as well as radiation yield in the MeV range at the interaction of a high power femtosecond laser pulse with a microstructured surface in comparison with a flat surface. Numerical simulations using 3D3V PIC code Mandor revealed that the charged particle energy growth is caused by the stochastic motion of electrons in the complex field formed by the laser field and the quasistatic field at the sharp tips of micromodifications.

Non-linear cumulative self-organization dynamics of femtosecond laser-induced surface relief ripples was for the first time experimentally revealed on a silicon surface as their primary appearance, degradation and revival, reflecting ultrafast non-linear dynamics of corresponding optical interference surface patterns. Such dynamics were revealed by electrodynamic modeling to be directly driven by related instantaneous surface optical patterns, which are sensitive not only to cumulative ripple deepening (steady-state feedback factor), but to laser-induced instantaneous variation of surface dielectric function, providing either positive or negative fluence-dependent optical feedbacks.

Metal-free mononuclear, dinuclear and trinuclear phthalocyanines were prepared by a mixed cyclotetramerisation of a 1,2,4,5-tetracyanobenzene derivative and 4,5-bis(2,6-dimethylphenoxy)phthalonitrile. For the first time, a pi-electron-conjugated trinuclear phthalocyanine was synthesised with phthalocyanine units connected by common annulated benzene rings. The Q band of the trinuclear compound in solution occurs at lambda = 944 nm whereas those of the dinuclear and mononuclear compounds are at lambda = 853/830 and 701/664 nm, respectively. Fluorescence quantum yields, fluorescence lifetimes and singlet-oxygen quantum yields of the compounds were determined.

Sub-micron quasi-regular surface textures were fabricated on surfaces of pure titanium (VT1-0) with micro- and ultrafine-grained bulk structures by multiple femtosecond laser pulses in the scanning mode and characterized by scanning electron and atomic force microscopy. Their wetting characteristics acquired for the initial non-textured and as-textured samples, as well as upon ultrasonic and plasma cleaning, demonstrate corresponding drastic changes of the wetting angles from 87° to ≤ 10°, with much more pronounced contamination, cleaning and wetting effects for the ultrafine-grained titanium.

Single- and multi-shot femtosecond laser surface ablation of a single-wall carbon nanotube-based substrate at 515- and 1030 nm wavelengths was studied by scanning electron microscopy and micro-Raman spectroscopy. The laser ablation proceeds in two ways: as the low-fluence mesoscopic shallow disintegration of the surface nanotube packing, preserving the individual integrity and the semiconducting character of the nanotubes or as the high-fluence deep material removal apparently triggered by the strong intrinsic or impurity-mediated ablation of the individual carbon nanotubes on the substrate surface.

One-dimensional transverse (perpendicular to the laser polarization) gratings with periods Λ ≈ 50–60 nm were observed on a titanium surface within 150 nm wide, micrometer-long regular surface modification longitudinal stripes fabricated by multiple 744 nm Ti:sapphire femtosecond laser shots, occurring at a repetition rate of 10 Hz. In the center of the surface laser spot these stripes are oriented strictly perpendicular to the laser polarization, in accordance with the plasmon-polaritonic model, and appear as ablative longitudinal trenches centered along the main stripe axes, which are precursors of longitudinal common ripples with a 500 nm period. At the low-fluence periphery of the laser spot, the stripes appear not as ablative longitudinal trenches, but as linear arrays of sub-ablative transverse nanoripples with periods down to 50 nm. The appearance of such superfine transverse nanoripples is related to incomplete spallation of the laser–molten surface layer, periodically modulated at the nanoscale through coherent sub-surface cavitation.

Femtosecond laser modification of titanium surfaces was performed to produce microstructured hydrophilic and biocompatible surface layers. Biocompatible nano/microcoatings were prepared for the first time by dry femtosecond laser imprinting of hydroxylapatite nano/micropowder onto VT6 titanium surfaces. In these experiments HAP was first deposited onto the titanium surfaces and then softly imprinted by multiple femtosecond laser pulses into the laser-melted surface metal layer. The surface relief was modified at the nano- and microscales depending on the incident laser fluence and sample scanning speed. Wetting tests demonstrated that the wetting properties of the pristine Ti surface can be tuned through its laser modification in both the hydrophobic and hydrophilic directions.

Summary form only given. A model of an atmospheric pressure HeCd laser pumped by a pulsed electron beam has been developed which makes it possible to calculate temporal and energy characteristics of the laser radiation. Processes restricting the specific pumping energy have been analyzed under optimal conditions of medium excitation. It is shown that the repetitive-pulse operation with a small duty ratio can be realized in the HeCd laser. Time and energy characteristics have been studied numerically of the radiation from a high pressure HeCd laser excited by a microsecond electron beam at wavelengths of 441.6 and 537.3 nm which depends on the pump duration, namely, the efficiency rises as the pump duration is reduced. A method is suggested for enhancement of the laser power at long pump pulses, which consists of increasing the temperature of the HeCd plasma electrons with the use of an external electric field. The optimal field strength has been determined. It is shown that the emitted radiation power can be modulated by means of pulsed switching of the electric field. The shape of the secondary electron degradation spectrum has weak influence on pumping rates of upper laser levels by direct electron impact, therefore lasings are identical in the case of equality of energy depositions.