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ABSTRACT: We report the recent results of research focused on a new kind of soft matter – the
liquid-crystal nanocomposites with controllable mechanical and nonlinear optical properties.
These are promising media for implementation of ultra-compact photonic devices and efficient
sources of coherent radiation in a wide spectral range. We overview the technology of
preparation of nematic-liquid-crystal media saturated with disclination defects. The defects
were formed in different ways: by embedding nanoparticles and molecular objects, by
exposure to alpha-particle flux. The defect locations were controlled by applying an electric
field. We also present and discuss the recently discovered features of nematic-liquid-crystal
media: a thermal orientation effect leading to the fifth-order optical nonlinearity, enormous
second-order susceptibility revealed by measurements, and structural changes upon exposure to
laser radiation. We report on efficient generation of harmonics, sum and difference optical
frequencies in nematic-liquid-crystal media. In addition, transformation of laser radiation
spectra to spectral supercontinua, and filamentation of laser beams were also observed in
nematic-liquid-crystal media. We conclude that most nonlinear optical effects result from
changes of the orientational order in the examined nematic liquid crystals. These changes lead
to the symmetry breaking and disclination appearances.
Journal of Physics Conference Series 01/2012; 345:012018.
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ABSTRACT: We develop a concept of atomic clocks where the blackbody radiation shift and its fluctuations can be suppressed by 1-3 orders of magnitude independent of the environmental temperature. The suppression is based on the fact that in a system with two accessible clock transitions (with frequencies ν1 and ν2) which are exposed to the same thermal environment, there exists a "synthetic" frequency ν(syn) ∝ (ν1 - ε12ν2) largely immune to the blackbody radiation shift. For example, in the case of 171Yb+ it is possible to create a synthetic-frequency-based clock in which the fractional blackbody radiation shift can be suppressed to the level of 10(-18) in a broad interval near room temperature (300±15 K). We also propose a realization of our method with the use of an optical frequency comb generator stabilized to both frequencies ν1 and ν2, where the frequency ν(syn) is generated as one of the components of the comb spectrum.
Physical Review Letters 07/2011; 107(3):030801. · 7.37 Impact Factor
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ABSTRACT: In this paper are present results of the first investigation of stimulated Raman scattering (SRS) in the “garnet” Lu3Al5O12 crystalline ceramics, which is promising hostmaterial for activator lasants. With picoseconds laser excitation at 0.53207 μm wavelength was observed and analyzed highorder Stokes and anti-Stokes generation related to two χ(3)-promoting vibration modes (≈792 and ≈375 cm–1) of this novel SRS-active oxide material. A brief review of the pioneering papers on lasers based on Lu3Al5O12:Ln3+ single crystals and known SRS-active crystalline “garnet” materials is given in tabular form as well. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 04/2011; 8(6):458 - 464. · 9.97 Impact Factor
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ABSTRACT: Monoclinic Y2SiO5 was found to be an attractive, simultaneously laser and χ(3)-nonlinear active optical crystal. Passively Q-switched LD-pumped nanosecond Nd3+:Y2SiO5 self-Raman laser, operating by nonlinear-cascaded scheme is reported. We achieved also quasi-CW generation of Y2SiO5:Nd3+ at 1.3585 μ m. Many-wavelength Raman-induced χ(3)-lasing in undoped Y2SiO5 under picosecond excitation has been observed, as well. All recorded Stokes and anti-Stokes components were identified and attributed to SRS-promoting vibration modes. Gives a short review of self-Raman lasers and laser potential of rare-earth C2h6-monoclinic orthosilicates doped with Ln3+ lasants. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 02/2010; 7(4):270 - 279. · 9.97 Impact Factor
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ABSTRACT: Raman-induced many-phonons Stokes and anti-Stokes generation in a orthorhombic crystals KHC6H4(COO)2 and (NH4)HC6H4(COO)2 under picosecond pumping has been observed. All recorded nonlinear lasing lines in the visible and near-IR regions are identified and attributed to the χ(3)-promoting vibration modes of these orthorhombic phthalates. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 03/2009; 6(7):544 - 551. · 9.97 Impact Factor
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ABSTRACT: A solution to the key problem of femtosecond metrology — elimination of the frequency offset related to the intracavity dispersion of a femtosecond laser — is proposed. The proposed method involves stabilisation of the intermode interval between equidistant spectral components in a frequency comb produced by a mode-locked femtosecond laser by phase-locking the frequency difference between a pair of discrete spectral components in this comb to the frequency of a reference laser. An introduction of a nonlinear-optical crystal for frequency doubling into the scheme for frequency-comb stabilisation allows the frequency offset related to the intracavity dispersion of the femtosecond laser to be eliminated, thus suggesting the way for absolute stabilisation of frequency combs generated by femtosecond mode-locked lasers. Radiation of a reference laser with such an approach plays the role of an anchor in the femtosecond clockwork.
Quantum Electronics 10/2007; 32(4):311. · 0.83 Impact Factor
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ABSTRACT: A ~20-mW cw radiation source is developed emit-ting at a wavelength of 457 nm with the linewidth less than 30 kHz. The source is based on a Ti:sapphire laser with freq-uency doubling in an external cavity containing a nonlinear LBO crystal. The results of high-resolution spectroscopy of magnesium atoms in separated optical fields, which demonstrate the possibilities of the system, are presented.
Quantum Electronics 10/2007; 31(6):495. · 0.83 Impact Factor
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ABSTRACT: A cw semiconductor laser with external feedback provided by a diffraction grating was investigated experimentally. The laser drive current was modulated at a frequency of 0.3–5 GHz. The spectrum of the output radiation consisted of several equidistant frequencies and the intervals between these frequencies were determined by the current-modulation frequency. Optimal conditions were found for the generation of the maximum number of such frequency components. The maximum width of the spectrum was 48 GHz. A method was developed for measuring the difference frequencies in the optical range with the aid of such lasers.
Quantum Electronics 10/2007; 29(2):109. · 0.83 Impact Factor
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ABSTRACT: Stimulated emission as a result of the inter-Stark transition in the 1-μm 4F3/2→4I11/2 channel of Nd3+ ions was excited for the first time in an acentric disordered SrxBa1-x(NbO3)2 (x≈0.6) crystal. The low-threshold lasing of this crystal at the 1.0626 μm wavelength was accompanied by diffuse intracavity generation of the second harmonic.
Quantum Electronics 10/2007; 28(12):1031. · 0.83 Impact Factor
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ABSTRACT: We developed a new method for fabrication of oxide laser ceramics. Its prospects were conclusively confirmed by efficient lasing at two wavelengths ≈1064 nm (4F3/2 → 4I11/2) and ≈946 nm (4F3/2 → 4I9/2) of Nd3+ ions in Y3Al5O12 ceramics with laser-diode pumping. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Physica Status Solidi (A) Applications and Materials 06/2007; 204(7):2411 - 2415. · 1.46 Impact Factor
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ABSTRACT: This article summarizes a study of the Brownian motion, at small temporal and spatial scales, of microparticles suspended in liquids. Using a phase-sensitive laser spectroscopy method, the thermal diffusion motion of test microparticles have been observed leading to a square law of Brownian motion at sufficiently small time scales.
Actual Problems of Electronic Instrument Engineering, 2006. APEIE '06. 8th International Conference on; 10/2006
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ABSTRACT: The processes of diffusion and filtration are slow, and therefore a full cycle of gas exchange and metabolism at the level of capillaries of the blood circulation system cannot be realized in such a short time. A special laser setup was created for noncontact, noninvasive investigation of microcirculation and transcapillary exchange in a living object. With the help of investigations by using this setup, a phenomenon unknown before, that of the formation of an acoustic field in the lumens of microvessels (arterioles, capillaries, and venules) was discovered. With the help of the laser method, we detected that the transverse motion of the walls of microvessels in the high-frequency range really takes place. The authors advanced the problem of active interaction of moving erythrocytes in microvessels with smooth muscle cells of their walls for the first time. In blood vessels, smooth muscle elements are packed spirally. We suggest that there exists a special mechanism of regulation of metabolic processes.
Actual Problems of Electronic Instrument Engineering, 2006. APEIE '06. 8th International Conference on; 10/2006
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ABSTRACT: Efficient room-temperature high-order Stokes and anti-Stokes steady-state generation in two wide-used hostcrystals LuVO4 and CaF2 for lanthanide lasants has been discovered. All recorded χ(3)-lasing components are identified to the SRS-promoting phonon modes of these crystals. We classi- fied lutetium vanadate and fluorite as media for promising for up- and down-Raman laser-frequency converters, as well as for self-SRS lasers. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 05/2006; 3(8):385 - 391. · 9.97 Impact Factor
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ABSTRACT: We report on the first achievement of CW oscillation in Yb3+:Lu2O3 ceramic lasers (2F5/2 → 2F7/2 channel) under LD-pumping at 0.976 µm wavelength, as well as present of the thickness of grain boundary layers in Lu2O3 ceramics was estimated under non-equilibrium acoustic phonon propagation kinetics at helium temperature (2.4–3.8 K). (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 04/2006; 3(8):375 - 379. · 9.97 Impact Factor
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ABSTRACT: Stokes and anti-Stokes picosecond generation in potential laser-host YbVO4 single crystal has been observed for the first time. All measured stimulated Raman scattering (SRS) wavelengths in the visible and near-IR are identified and attributed to the SRS-promoting vibration mode of this tetragonal vanadate. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 01/2006; 3(5):263 - 267. · 9.97 Impact Factor
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ABSTRACT: A new stage of development of optical clocks and synthesizers is possible with the use of highly stable femtosecond lasers.
Using femtosecond lasers and special optical fibres, a highly stable frequency comb covering the frequency interval up to
several hundreds of THz with a spacing from 100 MHz to 1 GHz has been developed. Experimental schemes for the femtosecond
optical clock based on the He-Ne/CH4 and Nd:YAG/I2 frequency standards are presented. The possibility of using tapered fibres for optical clocks and synthesizers is investigated.
It is shown that, depending on their influence on the frequency characteristics of the spectral components of the transmitted
radiation, tapered fibres can be used in femtosecond optical clocks and synthesizers.
12/2005: pages 87-108;
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ABSTRACT: We report on a high-energy ceramic Nd3+:Y3Al5O12 laser. Under the pyrotechnic explosion pumping, quasi-CW output power of about 1.1 KW (≈5.5 J) at 1.06415 µm wavelength (4F3/2 → 4I11/2 lasing channel) was achieved. Pyrotechnically pumped crystalline lasers are characterized by low size and cost, and the highest reported ratio of output energy to their weight. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Laser Physics Letters 10/2005; 3(3):124 - 128. · 9.97 Impact Factor
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ABSTRACT: The method of the experiment consisted in the measurement of the stability of the intermode frequency of the Ti:S laser (100 MHz) at the input and output of the fiber. Besides, two spectral areas of output radiation were extracted with the help of light filters, and the stability of intermode beats in extracted spectral regions was measured. To make these high-precision measurements, we developed and created a device. This device is based on the following principle. The intermode frequency is transferred by transformation into the low-frequency region, and then high-precision measurements of the chosen frequency (200 Hz) are made. It is noted that at the passage of a sequence of highly stable femtosecond pulses through a tapered fiber in the process of nonlinear transformation of modes, there is some decrease in the intermode frequency stability
Advanced Optoelectronics and Lasers, 2003. Proceedings of CAOL 2003. First International Conference on; 10/2003
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ABSTRACT: We present a theoretical study of broadened femtosecond frequency comb, affected by nonlinear fiber noises, by use of semi-qualitative numerical model based on the noise statistics and pulse propagation in fiber problem.
Quantum Electronics Conference, 2003. EQEC '03. European; 07/2003
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A. A. Kaminskii,
M. Sh. Akchurin,
V. I. Alshits,
K. Ueda,
K. Takaichi,
J. Lu,
T. Uematsu,
M. Musha,
A. Shirikawa,
V. Gabler,
H. J. Eichler,
H. Yagi,
T. Yanagitani, S. N. Bagayev,
J. Fernandez,
R. Balda
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ABSTRACT: Microhardness and fracture toughness of highly transparent Y3Al5O12-and Y3Al5O12: Nd3+-based nanocrystalline ceramics are measured for the first time. For the Y3Al5O12: Nd3+ laser ceramics, the use of a longitudinal scheme with a diode-laser pumping at a wavelength of 1.3186 mm (4
F
3/2 → 4
I
13/2 channel) enabled one to attain an output power of continuous-wave lasing of ∼3.7 W with 35% efficiency.
Crystallography Reports 01/2003; 48(3):515-519. · 0.47 Impact Factor
