Showing papers by "Andrey Popov published in 2010"

Master Robotic Net

Abstract: The main goal of the MASTER-Net project is to produce a unique fast sky survey with all sky observed over a single night down to a limiting magnitude of 19-20. Such a survey will make it possible to address a number of fundamental problems: search for dark energy via the discovery and photometry of supernovae (including SNIa), search for exoplanets, microlensing effects, discovery of minor bodies in the Solar System, and space-junk monitoring. All MASTER telescopes can be guided by alerts, and we plan to observe prompt optical emission from gamma-ray bursts synchronously in several filters and in several polarization planes.

Nonlinear optics of backward waves and extraordinary features of plasmonic nonlinear-optical microdevices

Abstract: Extraordinary properties and unique features of coherent nonlinear-optical coupling of ordinary and backward electromagnetic waves in negative-index metamaterials are described and numerically simulated. The possibility for design of unique microscopic photonic devices and all-optical data processing chips is shown.

Transient Detections and Other Real-Time Data Processing from MASTER-VWF Wide-Field Cameras

Abstract: Construction of robotic observatories has developed into an important and thriving field of astronomy. Their large field of view combined with the capability to be pointed at any direction makes robotic astronomical systems indispensable for tasks involving searches for transients like GRB, supernovae explosions, novae, and so forth, where both the time and direction of the search are impossible to predict. This paper describes prompt GRB observations made with MASTER-VWF wide-field cameras and the methods of image analysis and classification of transients used for real-time data processing. During seven months of operation six synchronous observations of gamma-ray bursts have been made using MASTER VWF facilities deployed in Kislovodsk and Irkutsk. In all cases high upper limits have been obtained.

Coherent nonlinear-optical energy transfer and backward-wave optical parametric generation in negative-index metamaterials

Abstract: The feasibility of all-optically tailored transparency of the negative-index slab, its extraordinary dependence on the intensity of the control field, absorption indices and phase-matching of the parametrically coupled counter-propagating waves is numerically simulated.

Synthesis and glass formation in the BaO-B2O3-BaCl2 system

Abstract: We have studied synthesis, glass formation, and crystallization processes in the oxychloride barium borate system BaO-B2O3-BaCl2 and determined the highest chlorine concentrations at which glasses can be prepared by mold casting for Ba: 2B ratios in the ranges 1.0–2.2 and 0.2–0.5. The process atmosphere has been shown to have a significant effect on the glass composition because of the chlorine release from the melt. We have determined the characteristic temperatures of the glasses and identified the crystalline phases that precipitate during cooling of the melt and heat treatment of the glasses.

Luminescent properties of Yb3+-doped hexagonal Ln3BWO9 (Ln = Gd, Y)

Abstract: We report the synthesis and spectroscopic characterization of polycrystalline Yb3+-doped (1, 2, and 5 at %) Ln3BWO9 (Ln = Gd and Y) borotungstates as candidate gain media for diode-pumped near-IR and visible solid-state lasers. Unpolarized luminescence and absorption spectra for the Yb3+ 2 F 7/2→2 F 5/2 transition are measured at T = 77 and 300 K, the lifetime of the 2 F 5/2 excited state is determined, and the emission cross section of the stimulated Yb3+ 2 F 5/2→2 F 7/2 transition in these compounds is evaluated. Offering a combination of nonlinear optical and lasing properties, the Ln3BWO9 (Ln = Gd, Y) hexagonal borotung-states can be used as bifunctional media for diode-pumped lasers with nonlinear laser frequency self-conversion.

All-Optically Transformable Broad-Band Transparency and Amplification in Negative-Index Films

Abstract: : Negative-index metamaterials (NIMs) exhibit highly unusual optical properties and promise a great variety of unprecedented applications. However, strong optical absorption inherent to such materials imposes severe limitation on such applications. The possibility to overcome this obstacle was proposed based on the coherent energy transfer from the control field to the signal through three-wave mixing, which is accompanied by optical parametric amplification (OPA) in NIMs. It was shown that the transparency exhibits an extraordinary resonance behavior as a function of intensity of the control field and the NIM slab thickness. Basically, such resonances are narrow and the sample remains opaque anywhere beyond the resonance field and sample parameters. Herein, we show that by adjusting the absorption indices for the signal and the idler, the slab can be made transparent and amplifying through the entire negative-index frequency domain and through a broad range of the slab thickness and intensity of the control fields provided that the product of the intensity and the thickness remains above the certain threshold.

Growth, optical parameters, and spectroscopic properties of crystals of disordered scheelite-like molybdates NaLa x Gd 1 − x (MoO 4 ) 2 ( x = 0–1) activated by Tm 3+ ions

Abstract: Polarized optical absorption spectra in the range of 450–2000 nm have been recorded for the Czochralski-grown concentration series of single crystals of mixed scheelite-like molybdates NaLa x Gd1 − x (MoO4)2(x = 0–1) activated by Tm3+ ions. The intensity parameters Ω t (t = 2, 4, 6) of the crystals grown were determined by the Judd-Ofelt method, and the values found were used to estimate the probabilities and emission branching ratios for a number of radiative transitions of Tm3+ ions. The main optical constants of an Na0.909La0.490Gd0.498Tm0.035Mo2.020O8.048 crystal were found and the temperature dependences of the refractive index for the ordinary and extraordinary waves were investigated in the temperature range of 293–373 K. The spectral dependences of the emission cross section for the expected 3 F 4 → 3 H 6 laser transition of Tm3+ ions in an Na0.908La0.301Gd0.676Tm0.048Mo2.019O8.043 crystal were measured in the spectral range of 1500–2000 nm. The gain cross section of the active medium on the 3 F 4 → 3 H 6 laser transition of Tm3+ ions in this crystal was calculated using the spectral dependences of the absorption and emission cross sections.

Backward-wave nonlinear-optical microchip

Abstract: The possibility of creation of remotely all-optically controlled microchip is described based on coherent nonlinear-optical energy exchange between ordinary and backward electromagnetic waves in negative-index metamaterials.