Effect of polarization and coherence of low-intensity optical radiation on fish embryos

  We have shown that brief exposure of sturgeon embryos (fertilized roe) in the organogenesis stage to low-intensity radiation in the visible region of the spectrum can have a long-term effect on embryonic and post-embryonic development of the fish, detectable 50 days after the irradiation procedure. The biological effects (size-weight characteristics and hardiness parameters of the fish relative to unfavorable habitat conditions) induced by linearly polarized emission from a monochromatic laser source (helium-neon laser, λ = 632.8 nm, Δλ ≈ 0.02 nm) and a quasi-monochromatic light-emitting diode (LED) source (maximum in emission spectrum λ = 631 nm, Δ λ = 15 nm) are practically the same. Going to broadband linearly polarized radiation (λ = 420–800 nm) is accompanied by a decrease in the biological effect. From the results of studies of the effect on embryos from linearly polarized and unpolarized radiation from an LED source and also the effect of linearly polarized, circularly polarized, and unpolarized radiation from a helium-neon laser, we concluded that the type of polarization is of critical importance in realization of the biological effect of radiation. In this case, the maximum stimulating effect (on the size×weight characteristics and the hardiness parameters for juvenile fish) is observed on exposure to linearly polarized radiation; the photobiological effect induced in the same dose range by light with natural polarization (i.e., unpolarized) is significantly less pronounced; the stimulating effect of circularly polarized radiation occupies an intermediate position. Based on the presented data and also on data obtained previously, we conclude that among the resonant and nonresonant photophysical processes (orientational effect of light, effect of gradient forces, dipole-dipole interactions, thermooptic processes) capable of inducing photobiological effects dependent on such laser-specific characteristics as polarization and coherence, the determining influence in the processes studied in this work comes from the orientational effect of light and dipole×dipole interactions. And the orientational effect can appear for anisotropic media with liquid-crystal type ordering (especially domains in membranes and multiple-enzyme complexes) both under conditions when there is no resonant absorption and for weakly absorbing structures, and can initiate a change in their conformations and accordingly their functional characteristics. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 843–858, November–December, 2008.     

The von Neumann representation as a joint time–frequency parameterization for polarization-shaped femtosecond laser pulses

We generalize the joint time–frequency von Neumann representation of femtosecond laser pulses for usage with time-dependent polarization states. The electric field is expanded in terms of Gaussian-shaped transform-limited subpulses located on a discrete time–frequency lattice, each with a specific polarization state. This formalism provides an intuitive picture for the time- and frequency-dependent polarization state. It can also serve as a basis for polarization pulse shaping. As an illustration, we define pulses for which polarization parameters (ellipticity and orientation) are given directly in time–frequency phase space. This approach has applications in quantum control and other areas for which time- and frequency-dependent light polarization is relevant.     

Polarization component method for calculation of the multiple-frequency lasing regime

We have shown that the polarization component method can be extended to the case of broadband emission (multiple-frequency approximation) if we make the approximation of slowly varying amplitudes and statistical independence of the polarization components. From the results of numerical modeling for the case of a liquid dye laser, it follows that the multiple-frequency approximation is meaningful to use for analysis of the spectral, polarization, and energy parameters in the region near and below the lasing threshold, and also for the statistical characteristics but taking into account saturation effects for the laser emission. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 346–350, May–June, 2007.     

Reconstructing the chargino system at e^+e^- linear colliders

In most supersymmetric theories charginos, , belong to the class of the lightest supersymmetric particles. The chargino system can be reconstructed completely in collider experiments: . By measuring the total cross sections and the asymmetries with polarized beams, the chargino masses and the gaugino–higgsino mixing angles of these states can be determined accurately. If only the lightest charginos are kinematically accessible in a first phase of the machine, transverse beam polarization or the measurement of chargino polarization in the final state is needed to determine the mixing angles. From these observables the fundamental SUSY parameters can be derived: the SU(2) gaugino mass , the modulus and the cosine of the CP–violating phase of the higgsino mass parameter , and , the ratio of the vacuum expectation values of the two neutral Higgs doublet fields. The remaining two–fold ambiguity of the phase can be resolved by measuring the normal polarization of the charginos. Sum rules of the cross sections can be exploited to investigate the closure of the two–chargino system. Received: 2 February 2000 / Published online: 17 March 2000     

Laser-induced fluorescence of cardiac tissue with calcinosis

Investigations of laser-induced fluorescence spectra for human cardiac valve tissue with calcinosis are performed as compared to similar spectra of bone and myocardial tissue of an animal that are excited by an excimer laser with a 248-nm wavelength. It is shown that a healthy tissue has a laser-induced fluorescence maximum in the region of 300–400 nm which corresponds to protein tissue luminescence. For tissue affected by calcinosis, the laser-induced fluorescence spectra differ significantly from the spectra of healthy tissue and have a maximum in the region of 400–500 nm. The obtained results offer the prospects for using laser-induced fluorescence to diagnose tissue with calcinosis in open-heart surgery. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 539–541, July–August, 1997.     

Controlled two-pulse generation in Q-switch mode from a single laser using Q-modulator with frustrated total internal reflection

In this work a cavity design for double-pulse generation in Q-switched mode from a single laser is proposed, based on the construction of a second laser channel using a FTIR (frustrated total internal reflection) Q-modulator. A time interval between the two pulses from 500 ns to 120 μs is obtained in a Nd:YAG laser. A comparison with other methods and cavity designs for double-pulse generation is presented. The case when this technique is applied on a tunable laser with metastable upper laser level (Cr:LiCAF, Cr:LiSAF, Alexandrite, Co:MgF₂ or other) is also considered. Even though the method presented in the paper does not rely only on the cavity configuration proposed, some advantages can be obtained – both polarization and wavelength-independent tuning without polarization and wavelength restrictions in combination with the possibility of different wavelengths and polarizations in each pulse. Moreover, by using an active medium generating wavelengths around and up to 3 μm, the Pockels-cell-Q-switch optical transmission problems can be avoided. Received: 9 May 2001 / Revised version: 2 August 2001 / Published online: 15 October 2001     

Background noise suppression in wide-band lasers with a nonlinear mirror in the cavity

An effective method for suppressing free background generation is proposed. It is based on polarization separation of the narrow-band output radiation of a controlled laser with a nonlinear mirror in the cavity. An increase in the integral ratio between the energy of the narrow generation line and the integral value of the energy of the background over the entire gain band of a wide-band laser from 0.17 to 55.00 has been attained. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 169–171, March–April, 2000.     

Complex degree of mutual anisotropy of linear birefringence and optical activity of biological tissues in diagnostics of prostate cancer

We present theoretical fundamentals of polarization and correlation analysis of the optical anisotropy of biological tissues. Results of measurements of coordinate distributions of the complex degree of mutual anisotropy (CDMA) that are formed by birefringent structures of the prostate tissue with benign and malignant changes are compared. Magnitudes and ranges of variation of statistical (the firstto fourth-order distribution moments) and correlation (excess of autocorrelation functions) parameters of the coordinate CDMA distributions of histological sections of the prostate postoperative bioptic material are studied. Objective criteria of the diagnostics of the appearance of pathology and of the differentiation of the degree of its severity are determined.     

Numerical model for pulsations in polarization of emission from a laser with an anisotropic cavity when initiated in a magnetic field

Based on equations for the evolution of the polarization density matrix for laser emission, we have shown that when a laser with an anisotropic cavity is turned on in a magnetic field higher than some critical value, we will observe a new optical effect: pulsations between the polarized and completely unpolarized states of the laser emission. In a magnetic field much higher than the critical value, practically complete suppression of polarization occurs, which may serve as a method for obtaining unpolarized laser emission. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 134–142, January–February, 2008.     

Spectral and spectral-polarization characteristics of potato leaves

The results of laboratory investigations of the spectral and spectral-polarization characteristics of radiation reflected from the leaves of potato(Solanum tuberosum) of different varieties are discussed. During the vegetation season of 1997, the angular dependence of the degree and azimuth of polarization of radiation reflected from potato leaves as well as the scattering indicatrices in the range 380–1080 nm were determined by a specially developed method with the use of a laboratory goniometric setup. The relationship between the spectral polarization characteristics of radiation and biological parameters of the potato has been obtained with the help of different methods of statistical analysis and explained on the basis of the known physical mechanisms. Translated from Zhurnal Prikladnoi Spektroskopii. Vol. 67, No. 4, pp. 524–529, July–August, 2000.     

Possibilities of the method of phase-polarization selection of laser frequencies in strong fields

The spectra of Faraday rotation of the plane of polarization of laser radiation in strong radiation fields and a magnetic field were investigated for alkali atoms. The spectra were obtained using the known method of computer simulation of polarization effects in real multilevel atoms. The possibility of using these effects in the phase-polarization method of selection of laser frequencies was considered. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 61–64, January–February, 2000.     

Probing vacuum birefringence by phase-contrast Fourier imaging under fields of high-intensity lasers

In vacuum high-intensity lasers can cause photon–photon interaction via the process of virtual vacuum polarization which may be measured by the phase velocity shift of photons across intense fields. In the optical frequency domain, the photon–photon interaction is polarization-mediated described by the Euler–Heisenberg effective action. This theory predicts the vacuum birefringence or polarization dependence of the phase velocity shift arising from nonlinear properties in quantum electrodynamics (QED). We suggest a method to measure the vacuum birefringence under intense optical laser fields based on the absolute phase velocity shift by phase-contrast Fourier imaging. The method may serve for observing effects even beyond the QED vacuum polarization.     

Photoinduced optical activity of C<Subscript>70</Subscript> fullerene in organic solvents

We have experimentally studied for the first time the effect of photoinduced rotation of the plane of polarization for pulsed laser radiation in solutions of C₇₀ fullerene in organic solvents and their mixtures. We have shown that the effect is observed for elliptical polarization of the laser radiation and is absent for linear polarization. We present the results of a study of the nonlinear optical characteristics of the C₇₀ solutions. We discuss the physical mechanisms by which nonlinear gyrotropy is induced in solutions. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 93–99, January–February, 2009.     

Infrared luminescence of erbium-doped sodium lead germanate glass

The infrared optical properties of Er³⁺ ions are reported for 60GeO₂–20PbO–20Na₂O glass for two Er₂O₃ concentrations. From the optical absorption spectra, the Judd–Ofelt (J–O) parameters have been obtained and have been used to calculate radiative lifetimes and stimulated emission cross sections. A narrow emission band peaked at 1536 nm with exponential decay for both Er concentrations is observed. The measured lifetime decreases for increasing Er concentration, its value being very close, in the case of the lowest doping level, to the radiative lifetime calculated from J–O analysis. This, together with the relatively high emission cross section makes this glass suitable for laser applications.     

Limited volume thin film deposition on geometrically complicated substrates

In this paper we report a study on the elastic scattering of electrons by lithium and sodium atoms in the presence of circularly polarized resonant laser field within the framework of the two-state rotating wave approximation. The effect of laser on projectile electrons is described by Volkov states. The frequency of the laser field is chosen to match with the 2s–3p (3s–3p) transition frequency in lithium (sodium) atoms. The total and differential elastic cross sections with single photon exchange are calculated for intermediate energies (50–150 eV) and laser intensity (10⁷–10¹¹ W cm^-2). An erratum to this article can be found online at http://dx.doi.org/. An erratum to this article can be found at     

Assessment of the therapeutic action of low-intensity laser radiation from the extent of local tissue saturation with oxygen

We propose a method for dosimetry of the biological response to laser irradiation based on determination of the amount of oxygen additionally supplied to the tissue. We show that it is feasible to determine the therapeutic dose from the change in the degree of oxygen saturation of the blood, heart rate, hemoglobin concentration in the blood, and exposure time. __________ 13Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 516–520, July–August, 2006.     

Optical properties of Pr3+-doped SrWO4 crystal

The polarized absorption and emission spectra of Pr³⁺ ions in SrWO₄ single crystals were investigated at room temperature. The standard and modified Judd–Ofelt theories have been applied to analyze the polarized absorption spectra to determine the spectroscopic parameters, including the Judd–Ofelt intensity parameters Ω_t (t=2,4,6), radiative transition probabilities, radiative lifetimes and branching ratios. The stimulated emission cross sections and fluorescence lifetimes of the promising laser level were obtained. PACS 78.55.Hx; 42.70.Hj; 78.20.-e     

M<Superscript>2</Superscript> of MOPA CuBr Laser Radiation

The beam propagation factor, M² of the master-oscillator power-amplifier (MOPA) CuBr laser emission compliant with ISO 11146 is studied methodically. Statistical parameters of 2D intensity profile of the near and far fields of MOPA laser radiation are measured by a beam analyzing technique as functions of timing delay between MO and PA. For first time the influence of the gas buffer (causing the radiation profile to change from annular to top-hat and Gaussian-like) and light polarization on CuBr laser beam focusability (M²) was under investigation. The MOPA gain curve is found and the influence of gain on the input signal (from MO into PA) due to the absorption/amplification in PA on the field profiles is shown. For annular radiation M² range is from 13–14 (small delays) to 5–6 (large delays) and for filled-center radiation M² is 6–7 (small delays) and at the end of gain curve is as much as 4. With polarized light, M² drops to 3 at the end of gain curve. The brightness of laser emission with hydrogen goes up 3–5 times and the linearly-polarized beam is at least 40% brighter than that of partial or non-polarized beams.     

Distributed feedback dye laser holographically induced in improved organic–inorganic photocurable nanocomposites

Distributed feedback (DFB) lasing in permanent volume transmission gratings formed in a laser dye-doped organic–inorganic nanocomposite has been investigated. DFB laser cavities were fabricated using one-step two-beam holographic exposure of Pyrromethene 567 (PM567) doped photopolymerizable acrylate monomers containing inorganic (LaPO₄) nanoparticles. Compared to the formulation previously utilized, the material composition presented provides longer lifetime of the laser. Spectral and polarization properties, input–output and stability characteristics of the laser output have been investigated by varying the material composition and the patterning parameters. DFB lasing emission of the second and the third diffraction orders has been demonstrated. The spectral linewidth of ∼0.08 nm has been observed at a pump energy threshold of about 0.2 μJ/pulse for the second-order DFB lasing when pumped with 532 nm 500 ps laser pulses. Spectral tuning of the lasing output over ∼56 and ∼7 nm was obtained by varying the grating period and the content of inorganic nanoparticles in the polymer matrix, respectively.