Showing papers presented at "International Conference Laser Optics in 2018"

Macromolecular Imaging using X-ray free-electron lasers*

Abstract: X-ray crystallography, which is used for the determination of most biomolecular structures, has relied on Bragg diffraction from single crystals for more than a century. For many difficult to crystallize proteins, the growth of large well-ordered single crystals is a major challenge. Single molecule diffraction is a challenging but highly desired approach to structure determination, as it abolishes the need for crystallization and provides about four times higher information content than needed to solve a structure, unlike Bragg diffraction which is usually insufficient for direct phasing. Even using the powerful X-ray Free Electron Lasers, the challenges of this method have so far not been overcome to acquire atomic resolution structures. Recently, it was shown that the structure of a protein can be solved based on continuous diffraction from crystals with translational disorder.

Quantum cascade lasers grown on silicon

Abstract: We report the first quantum cascade lasers directly grown on a silicon substrate. These lasers are based on the InAs/AlSb material system and exhibit high performances, comparable with those of the devices fabricated on their native InAs substrate. The lasers operate near 11 μm, the longest emission wavelength of any laser integrated on Si.

Improving performance of quantum frequency standard with laser pumping

Abstract: One of the directions of improving performance of quantum frequency standard with laser pumping is considered. A summary of performance results that make it possible is provided.

Combined method for laser selection, positioning and analysis of micron and submicron cells and particles

Abstract: The concept of a combined measuring system for determination of the physical and dynamical parameters of a single micron and submicron particle is proposed in this paper. The results of an experimental testing and approbation of functional parts of the suggested system are presented.

Novel wearable VCSEL-based blood perfusion sensor

Abstract: A wearable 850 nm VCSEL-based blood perfusion sensor operating on the principles of laser Doppler flowmetry (LDF) and Dynamic Light Scattering (DLS) has been developed and tested. The sensitivity of the sensor to changes in skin blood perfusion has been demonstrated.

Thermal imaging by means of IR-fiber bundle for medical applications

Abstract: In this study we proposed a thermal imaging setup with an ordered bundle of silver halide IR-fibers. This bundle allowed us to obtain thermal images of objects with linear dimensions equivalent to the diameter of an individual fiber in the bundle. We expect such bundles will be applied in surgery monitoring systems for the tissues temperature estimation during laser cutting.

Self-assembled biomacromolecular films as a basis for nonlinear optical devices

Abstract: This paper is concerned with studies of protein films as a basis for nonlinear optical devices for biomolecular electronics, in particular, a molecular computer. A possibility of creation of an optical analog of a neural network based on the biomolecular film structure is considered. Some experiments on creation of specially structured films were conducted. The great influence of magnetic field on protein films structure was detected.

Targeting of tumor tissues with magnetic nanoparticles

Abstract: Magnet-enforced targeting of drug-loaded superparamagnetic iron oxide nanoparticles (SPIO-NP) towards malignant tumors appears to be a desirable tool to reduce adverse side effects of systemically applied drugs including biologicals such as specific monoclonal antibodies. In order to make magnetic targeting feasible for tumors in the depth of the body we propose to load red blood cells (RBC) with SPIO-NP and use them as blood-born carriers to target them to endothelial cells of the tumor neo-vasculature. We employ original optoelectronical techniques to monitor the uptake of SPIO-NP. Targeting will be achieved by labeling of RBC with antibodies recognizing receptors specifically expressed by tumor endothelial cells together with strong external magnets placed over tumors. Here, we report magnetic and optoelectronical in vitro experiments showing the feasibility of endothelial cell loading with SPIO-NP, encapsulation of derivatized SPIO-NP in RBC, surface conjugation of RBC with antibodies, their binding to cultured endothelial cells and subsequent internalization.

Synthesis of Luminescent Magnetic Nanoparticles with Controllable Surface Properties

Abstract: Luminescent magnetic nanoparticles are attractive agents for many biomedical applications such in vivo imaging, biosensing and drug delivery. Each of these applications needs particles with specific properties. Here we synthesized a library of magnetic luminescent nanoparticles with controlled sizes and zeta-potentials using silicate chemistry. Labeling of tumor cells with these nanoparticles and studying their pharmacokinetics was also discussed.

Direct Laser Deposition with Transversal Oscillating of Laser Radiation

Abstract: the objective of this research is investigation influence spot diameter, frequency and amplitude of transversal oscillating laser radiation on the efficiency and coefficient of using materials of the direct laser deposition. Efficiency and coefficient of using materials of the direct laser deposition were increased from 15 g/min up to 22.2 g/min and from 27.6% up to 44.4% accordingly at the transversal oscillating laser radiation with spot diameter 0.9 mm, frequency 100 Hz and amplitude 2.6 mm comparatively with seems indicator of the direct laser deposition with spot diameter 3.2 mm without oscillating.

Scattered laser beam control using bimorph deformable mirror

Abstract: The ability to focus laser beam (λ = 0.65 nm), propagated through the scattering medium, was investigated both numerically and experimentally. Numerical estimations were performed with the Monte Carlo simulation and Shack— Hartmann technique. Experimental setup with the bimorph mirror as a laser beam corrector and two kinds of sensors as feedback devices — Shack-Hartmann sensor and far-field focal spot analyzer — was designed. Three kinds of correction algorithms were tested and compared to each other.

Laser Correlation Spectroscopy for Immune Testing

Abstract: New results about the immune status of a human body estimation by dynamic light scattering (laser correlation spectroscopy) method are presented. A designed scheme of the laser correlation spectroscopy device allowed us to conduct measurements of blood proteins’ sizes and dynamics under the influence of external factors. These results will be used for development of preliminary diagnosis of immune diseases.

AgBr-TlI crystals for medium and far IR optics (2 – 60 µm)

Abstract: Phase diagram of AgBr-TlI was studied, and two regions of stable solid solutions were found in it. A series of optical crystals were grown basing on the detected homogeneity regions. Their optical properties (refractive index, transmission range, optical losses) were investigated. Slight changes in the refractive index over a wide range of compositions makes it possible to use these materials for creating 1D and 2 D structures including PCF structures.

OCT-based label-free 3D mapping of lymphatic vessels and transparent interstitial-fluid-filled dislocations

Abstract: Approach to OCT-lymphangiography (OCT-LA) and interstitial-fluid-filled dislocations mapping that complement speckle variance (SV) OCT angiography is presented. OCT-LA can be extracted from the same OCT raw datasets that were acquired for SV OCT angiography. Lymphatic vessels and interstitial dislocations are filled with transparent fluids (e.g. lymph) and can be separated from the blood vessels and tissue. In vivo application of the OCT-LA approach is demonstrated on NRG mouse with grown BX-PC3 tumor (human pancreatic cancer cells).

107-kW-Peak-Power 2-ns Pulse Tapered Er-doped Fiber Amplifier

Abstract: A novel tapered Er3+-doped fiber design for high peak power amplification has been developed and tested. The core diameter was changing along 2.5 meters from 22.5 μm (single-mode operation) to 86 μm. Amplification of 2 ns pulses has resulted in peak power of 105 kW (0.25 mJ) with nearly diffraction-limited beam quality (M2<1.27).

High-power passively mode-locked thulium-doped all-fiber ring laser with nonlinearity and dispersion management

Abstract: we developed a high-power dispersion-managed thulium-doped all-fiber ring laser passively mode-locked by nonlinear polarization evolution (NPE) effect. The laser generates 142.8 fs pulses at 1950 nm central wavelength with maximum average power of 370 mW and 57.4 nm spectral FWHM corresponding to the 31 nJ pulse energy and 222 kW pulse peak power.

Towards magnetoencephalography based on ultrasensitive laser pumped non-zero field magnetic sensor

Abstract: The principal possibility of creating optically pumped compact magnetic sensor for MEG operating in a wide magnetic field range is experimentally proved.

The Laser-Assisted Synthesis of Linear Carbon Chains Stabilized by Noble Metal Particles

Abstract: Metal-carbon materials realize surface-enhanced Raman scattering. Such structures were synthesized using the laser irradiation of colloidal systems consisting of carbon and noble metal nanoparticles.

Laser ablation of materials by femtosecond laser pulses in liquid media

Abstract: The paper presents an investigation of the interaction of ultrashort laser pulses with various materials in liquid media. The configuration of the laboratory installation is presented, the processing conditions are also described. Physical mechanisms of the observed phenomena are considered, the achieved results are described.

Optimization of selective photodestruction by laser radiation of the yellow-green range of capillary angiodysplasia of the skin.

Abstract: A laser medical device has been created to conduct an exact photodestruction of the vascular formations of the skin and subcutaneous tissue. Conducted studies on model biological objects for confirmation the possibility of realizing the optimal parameters of laser radiation providing photodestruction of hemoglobin containing tissues.

Magnetic Fluid Analysis by Optical Fiber Method

Abstract: The method of investigation of nanostructured material – magnetic fluid (ferrofluid) is developed in present work. It is based on registration of light, reflected from the optical fiber end, placed into the liquid sample, and exposed to external magnetic field. The contributions of Fresnel reflection and back scattering are estimated. The transient effects, appeared at the field switching on and switching off are discussed.

Complexed NIR laser detector and LWIR camera optical system with neural network management for UAV collision avoidance system

Abstract: We developed a compact and lightweight multispectral active optical system for detection of passive diffusely-reflecting and active thermal objects. The system acts as an automatic collision avoidance system used for ultra-light UAVs. The system contains an active laser detector and a passive LWIR finder. The different types of detectors are complexed by means of neural network realized on 256 core video processor. The fast response is realized by field-programmable gate array processing of the raw signal.

Non-contact laser speckle anemometry of microcirculatory bloodstream

Abstract: In the work the scheme of the differential sensor for non-invasive distant anemometry of microcirculatory bloodstream is described. The sensor is designed on base of the laser speckle theory. Some important parameters like maximal distance and time of measurement are calculated. Experimental results on blood speed determination are presented.

Fluorescent Superparamagnetic and Paramagnetic Agents for Bioimaging, Sensing and Cell Targeting

Abstract: Nanocomposite materials are of great interest as a multipurpose instrument for various biomedical applications. In the presented work, we demonstrate the capability of fluorophore-modified nanoparticles based on iron oxides and oxyhydroxides crystallites to act as multimodal agents that combine specific recognition of target cells with properties of materials used for fluorescent bioimaging and MRI-contrasting.

Generation of magnetic fields behind the front of an electrostatic shock wave in a laser plasma

Abstract: The expansion of a hot dense plasmoid through a rarefied ionized medium has been studied experimentally and numerically. The plasma was evaporated from an alumium foil by a femtosecond laser pulse and propagated through a cold and tenuous plasma, generated from the same foil by a laser precursor. A density bump associated with a collisionless electrostatic shock wave was detected. Depolarization of a probe laser beam in the region behind the bump suggests that a strong magnetic field exists there. PIC-simulations show that the bump emerges due to the presence of the background and is exposed to a continuous flow of hot electrons from the plasmoid. At about 1000 inverse plasma frequencies of the dense plasma the anisotropy of the electron temperature, arising behind the shock, leads to the Weibel instability and growth of a quasi-static inhomogeneous magnetic field up to a magnetization level of 0.1.

Dynamic Optical Coherence Elastography of Soft Tissue

Abstract: Optical coherence elastography (OCE) is relatively new emerging method allowing to assess biomechanical properties of tissues in situ and in vivo in 3D. In this talk I will overview recent progress made in the quantitative assessment of viscoelasticity of ocular and cardiac tissues

Monitoring of slow deformations in laser tissue reshaping with optical coherence elastography

Abstract: Strain mapping based on analysis of complexvalued signal of optical coherence tomography (OCT) is applied to monitor slow deformations of biological tissues (e.g., cartilage or cornea) subjected to thermo-mechanical reshaping by moderate heating with an IR laser. Insufficiently relaxed internal stresses may slowly distort the required tissue shape on a scale from minutes to hours with strain rate ~10−4 s−1. We show the ability of the developed OCT method to monitor strains with uncertainly ~10−5 on ~102 s intervals sufficient for shape-stability verification in intra-operational preparation of cartilaginous implants.

Near-IR InAs/GaAs Quantum-Dot Lasers and their Application for Efficient Frequency Conversion

Abstract: In this talk, I will review our recent results on the development of novel, compact, continuous-wave (CW) and ultrashort pulse, near-infrared (near-IR) InAs/GaAs quantumdot (QD) based lasers and their application for the generation of light in the visible and terahertz (THz) spectral regions. This will include a discussion on the recent achievements in the development of broadly-tunable InAs/GaAs QD external-cavity diode lasers (ECDLs) in the CW and mode-locked (ML) regimes, an overview of the advances made with second harmonic generation (SHG) in periodically poled nonlinear crystalwaveguides pumped by these lasers and a discussion on application of InAs/GaAs QD-based lasers for the development of ultra-compact room-temperature THz-generating laser sources.

Fine Spectral Structure and Ultra-monochromatic Tunable Terahertz Radiation of the NovoFEL

Abstract: Laser nature of a continuous pulse-periodical radiation of the Novosibirsk free-electron laser (NovoFEL) appears in a good coherency of its many longitudinal modes. Filtration of one of the modes by a system of three resonance Fabry-Perot interferometers allows to create laser source with monochromaticity which is sufficient for typical high-resolution THz spectroscopy (≤ 2 ⋅ 10-7, ≤ 0.5 MHz). Features of the source compared to other alternative devices are a wide tuning range (1.5–3 THz) and much more high output power (up to 100 mW).

Hybrid mode-locking of an all-fiber holmium laser.

Abstract: We have investigated the laser radiation parameters of the hybrid mode-locked holmium-doped fiber laser. To realize this regime we have combined nonlinear polarization evolution (NPE) and carbon nanotubes (CNT) as an additional nonlinear saturable absorber.