Spatially Structured Optical Pump for Laser Generation Tuning.

The goal and essential parameter of laser light conversion is achieving emitted radiation of higher brightness. For many applications, the laser beam must have the highest available beam quality and highest achievable power. However, lasers with higher average power values usually have poorer beam quality, limiting the achievable brightness.

Super-collimation by axisymmetric diffractive metamirror.

We propose and demonstrate experimentally super-collimation of light beams by an axisymmetric diffractive metamirror-an axisymmetric concentric dielectric ring structure positioned in front of a mirror at a distance of several micrometers. By super-collimation, we mean the formation of a well-collimated beam characterized by a substantial enhancement of its axial component in the far-field domain. In the reported experiments, the axial intensity of the field was enhanced by around six times.

Application of P(VDF-TrFE) Glass Coating for Robust Harmonic Nanoparticles Characterization.

Polyvinylidene fluoride and its copolymers are a well-known family of low-cost ferroelectric materials widely used for the fabrication of devices for a wide range of applications. A biocompatibility, high optical quality, chemical and mechanical durability of poly(vinylidene fluoride-trifluoroethylene), (P(VDF-TrFE)), makes it particularly attractive for designing of effective coating layers for different diagnostic techniques. In the present work, the nonlinear optical characterization of P(VDF-TrFE)-coating films deposited onto a glass substrate was done.

Using Metal-Multilayer-Dielectric Structure to Increase Sensitivity of Surface Plasmon Resonance Sensor.

We propose using a specially designed metal-multilayer-dielectric structure deposited on glass substrate to enhance the evanescent field and improve the sensitivity of the surface plasmon resonance sensor. The proposed structure supports both hybrid plasmonic transverse magnetic modes and conventional waveguide transverse electric modes. We show numerically the significant enhancement of the evanescent field and improvement of the sensitivity for the waveguide transverse electric mode.

Photonic Crystal Microchip Laser.

The microchip lasers, being very compact and efficient sources of coherent light, suffer from one serious drawback: low spatial quality of the beam strongly reducing the brightness of emitted radiation. Attempts to improve the beam quality, such as pump-beam guiding, external feedback, either strongly reduce the emission power, or drastically increase the size and complexity of the lasers. Here it is proposed that specially designed photonic crystal in the cavity of a microchip laser, can significantly improve the beam quality.

Metal-Multilayer-Dielectric Structure for Enhancement of s- and p-Polarized Evanescent Waves.

We propose a structure based on combination of multilayer stack of dielectric films and thin metal layer for excitation and enhancement of both s- and p-polarized evanescent waves. It is shown that two different mechanisms of evanescent wave excitation may occur at the same angle of light beam incidence on the structure. Application for evanescent wave polarization holographic recording with the help of this structure is discussed.

Foetal dose conversion coefficients for ICRP-compliant pregnant models from idealised proton exposures.

Protection of pregnant women and their foetus against external proton irradiations poses a unique challenge. Assessment of foetal dose due to external protons in galactic cosmic rays and as secondaries generated in aircraft walls is especially important during high-altitude flights. This paper reports a set of fluence to absorbed dose conversion coefficients for the foetus and its brain for external monoenergetic proton beams of six standard configurations (the antero-posterior, the postero-anterior, the right lateral, the left lateral, the rotational and the isotropic).

Fluence to absorbed foetal dose conversion coefficients for photons in 50 keV-10 GeV calculated using RPI-P models.

Radiation protection of pregnant females and the foetus against ionising radiation is of particular importance to radiation protection due to high foetal radiosensitivity. The only available set of foetal conversion coefficients for photons is based on stylised models of simplified anatomy. Using the RPI-P series of pregnant female and foetus models representing 3-, 6- and 9-month gestation, a set of new fluence to absorbed foetal dose conversion coefficients has been calculated.

Fluence-to-absorbed-dose conversion coefficients for neutron beams from 0.001 eV to 100 GeV calculated for a set of pregnant female and fetus models.

Protection of fetuses against external neutron exposure is an important task. This paper reports a set of absorbed dose conversion coefficients for fetal and maternal organs for external neutron beams using the RPI-P pregnant female models and the MCNPX code. The newly developed pregnant female models represent an adult female with a fetus including its brain and skeleton at the end of each trimester.

Spatial solitons in a pumped semiconductor resonator.

Bright and dark spatial solitons are observed in an optically pumped semiconductor resonator. The pumping allows us to reduce considerably the light intensity necessary for the existence of the solitons and alleviates thermal load problems. Experiments are found to agree qualitatively with calculations based on a simple large-aperture semiconductor resonator model.

A boundary-representation method for designing whole-body radiation dosimetry models: pregnant females at the ends of three gestational periods--RPI-P3, -P6 and -P9.

Fetuses are extremely radiosensitive and the protection of pregnant females against ionizing radiation is of particular interest in many health and medical physics applications. Existing models of pregnant females relied on simplified anatomical shapes or partial-body images of low resolutions. This paper reviews two general types of solid geometry modeling: constructive solid geometry (CSG) and boundary representation (BREP).

Bistable phase locking of a nonlinear optical cavity via rocking: Transmuting vortices into phase patterns.

We report the experimental observation of the conversion of a phase-invariant nonlinear system into a bistable phase-locked one via rocking [G. J. de Valcárcel and K.

Hysteretic nonequilibrium Ising-Bloch transition.

We show that a parametrically driven cubic-quintic complex Ginzburg-Landau equation exhibits a hysteretic nonequilibrium Ising-Bloch transition for large enough quintic nonlinearity. These results help to understand the recent experimental observation of this phenomenon [A. Esteban-Martín, Phys.

Controlled observation of a nonequilibrium Ising-Bloch transition in a nonlinear optical cavity.

We report the controlled observation of the nonequilibrium Ising-Bloch transition in a broad area nonlinear optical cavity (a quasi-1D single longitudinal-mode photorefractive oscillator in a degenerate four-wave mixing configuration). Our experimental technique allows for the controlled injection of the domain walls. We use cavity detuning as control parameter and find that both Ising and Bloch walls can exist for the same detuning values within a certain interval of detunings; i.

Control and steering of phase domain walls.

We show experimentally the feasibility of optically controlled location, individual addressing/erasure and steering of phase domain walls by injection of coherent addressing pulses into a phase-locked four-wave-mixing photorefractive oscillator.

Estimation of internal and external exposures of terrestrial reference organisms to natural radionuclides in the environment.

In this paper, an estimation of the doses absorbed by terrestrial reference organisms due to naturally occurring radionuclides is described. For terrestrial organisms under normal circumstances, external exposure is estimated to be of the order of 0.1-0.

Absorbed dose rate conversion coefficients for reference terrestrial biota for external photon and internal exposures.

The paper describes dosimetric models that allow the estimation of average radiation exposures to terrestrial biota due to environmental sources in the soil as well as internal uniform distributions of radionuclides. Simple three-dimensional phantoms for 13 faunal reference organisms are specified. The calculation of absorbed dose per unit source strength for these targets is based on photon and electron transport simulations using the Monte Carlo method.

On an evaluation of external dose values in the Techa River Dosimetry System (TRDS) 2000.

Absorbed doses were determined by thermoluminescence (TL) measurements for bricks from a height of 6 m from the south-western wall of the former mill in Metlino that faced the Techa river. Measurements of the internal beta-radiation and alpha-radiation in the brick samples and of radionuclide activities in soil samples from the Techa river valley were performed. The absorbed dose in bricks due to the natural radiation was derived and subtracted from the total dose in order to obtain the absorbed dose in the bricks caused by anthropogenic sources.

Spatial resonator solitons.

Spatial solitons can exist in various kinds of nonlinear optical resonators with and without amplification. In the past years different types of these localized structures such as vortices, bright, dark solitons, and phase solitons have been experimentally shown to exist. Many links appear to exist to fields different from optics, such as fluids, phase transitions, or particle physics.

Verification of external exposure assessment for the upper Techa riverside by luminescence measurements and Monte Carlo photon transport modeling.

An area located in the Southern Urals was contaminated in 1949-1956 as a result of radioactive waste releases into the Techa river by the Mayak Production Association. The external dose reconstruction of the Techa river dosimetry system (TRDS-2000) for the exposed population is based on an assessment of dose rates in air (DRA) obtained by modeling transport and deposition of radionuclides along the river for the time before 1952 and by gamma dose rate measurements since 1952. The aim of this paper is to contribute to a verification of the TRDS-2000 external dose assessment.

Nonlinear coherent polarimetry for measuring the complex nonlinear index.

A novel polarimetric technique for measuring the nonlinear change of optical polarization at a vector two-wave mixing interaction is described and demonstrated as an absorption and refraction of bacteriorhodopsin.

[Activation of free-radical processes as a factor of ionizing radiation-induced changes in contractile activity of a vascular wall].

The influence of ionizing irradiation (1, 2 and 4 Gy 137Cs) on both the activity of free-radical processes in plasma, formed elements and aorta wall as well as on the character of contractile vascular reactions of isolated rings of thoracic aorta and carotid artery in rabbits has been studied. The experiments were carried out on the 7th day after the whole-body irradiation. The results indicate that simultaneously with the weakening of antioxidant mechanisms both endothelium-dependent and endothelium-independent vascular wall relaxation slightly decreases after 1 Gy exposure.

[The vascular protective effect of the combined administration of magnesium chloride and antioxidants in prolonged hypercholesterolemia ].

The angioprotective efficacy of combined application of magnesium chloride and antioxidants during prolonged hypercholesterolemia has been investigated on the experimental model of atherosclerosis in rabbits. The application of magnesium chloride and acetate tocopherol from the very beginning of the atherogenic diet is shown to exert a pronounced angioprotective effect preventing the development of structural and functional changes in the aorta wall. If the treatment is initiated against the background of the well developed atherosclerotic symptoms, its efficacy is less pronounced but remains still on a quite high level.

[Changes in the responsive ability of parietal associative cortex neurons to stimulation of associative thalamic nuclei during development of inhibition].

Neuronal responses of area 7 of the parietal associative cortex (PAC) to paired stimulation of the nLD and nLP thalamic nuclei were investigated by extra- and intracellular recording methods. It was found out that testing stimulation of the associative nuclei resulted in inhibition, facilitation or absence of clear neuronal responses. Inhibition was observed more often then other types of reactions.