Kolokoltsev O.,National Autonomous University of Mexico |
Gomez-Arista I.,National Autonomous University of Mexico |
Trevino-Palacios C.G.,National Autonomous University of Mexico |
Qureshi N.,National Autonomous University of Mexico |
Mejia-Uriarte E.V.,Instituto Nacional Of Astrofsica
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2016
We present a simple modification to a swept source optical system that overcomes the limitations in the depth range associated with the short coherence length of fast swept lasers. It is based on a wavelength dependent delay induced by a diffraction grating pair with negative dispersion incorporated in a reference arm of a Mach-Zehnder optical coherence tomography interferometer. The experimental depth range in air obtained was as large as 1.6 cm for a source coherence length of 4 mm. © 1995-2012 IEEE.
Carrada R.,Instituto Nacional Of Astrofsica |
Arrizon V.,Instituto Nacional Of Astrofsica |
Ruiz U.,Instituto Nacional Of Astrofsica
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
A numerical and experimental comparison between different synthetic holographic codes is presented. Its performance is evaluated considering the generation of Bessel and Laguerre-Gaussian beams, as examples. Some reviews of computer generated holograms (CGHs)1, 2 have been published in the literature but none of them have included a detailed comparison of their performance in the encoding of structured optical fields. The numerical evaluation includes an analysis of the theoretical features of each hologram and a calculation of Signal-to-Noise Ratio of the reconstructed field while the experimental evaluation assume the implementation of the holograms using a pixelated phase modulator. © 2010 SPIE.
Dewangan L.K.,Instituto Nacional Of Astrofsica |
Mayya Y.D.,Instituto Nacional Of Astrofsica |
Luna A.,Instituto Nacional Of Astrofsica |
Ojha D.K.,Tata Institute of Fundamental Research
Astrophysical Journal | Year: 2015
We report on the discovery of an infrared jet from a deeply embedded infrared counterpart of the 6.7 GHz methanol maser emission (MME) in W42 (i.e., W42-MME). We show that W42-MME drives a parsec-scale H2 outflow, with the detection of a bow shock feature at ∼0.52 pc to the north. The inner ∼0.4 pc part of the H2 outflow has a position angle of ∼18° and the position angle of ∼40° is found farther away on either side of the outflow from W42-MME. W42-MME is detected at wavelengths longer than 2.2 μm and is a massive young stellar object with an estimated stellar mass of 19 ± 4 . We map the inner circumstellar environment of W42-MME using Very Large Telescope (VLT)/NACO adaptive optics Ks and L' observations at resolutions of ∼0.″ 2 and ∼0.″1, respectively. We discover a collimated jet in the inner 4500 AU using the L' band, which contains prominent Brα line emission. The jet is located inside an envelope/cavity (extent ∼10,640 AU) that is tapered at both ends and is oriented along the north-south direction. Such observed morphology of the outflow cavity around the massive star is scarcely known and is very crucial for understanding the jet-outflow formation process in massive star formation. Along the flow axis, which is parallel to the previously known magnetic field, two blobs are found in both the NACO images at distances of ∼11800 AU, located symmetrically from W42-MME. The observed W42-MME jet-outflow configuration can be used to constrain the jet launching and jet collimation models in massive star formation. © 2015. The American Astronomical Society. All rights reserved.
Cosme I.,Instituto Nacional Of Astrofsica |
Kosarev A.,Instituto Nacional Of Astrofsica |
Temoltzi F.,Instituto Nacional Of Astrofsica |
Itzmoyotl A.,Instituto Nacional Of Astrofsica
CCE 2011 - 2011 8th International Conference on Electrical Engineering, Computing Science and Automatic Control, Program and Abstract Book | Year: 2011
This paper reports the study of Ge ySi 1-y:H films deposited at temperatures in the range of T d= 70 to 300 °C. The films were grown in capacitive low-frequency (f=110 KHz) discharge from Si:H 4 and Ge:H 4 feed gases diluted with H 2. Other parameters were as follow: hydrogen flow Q H2= 3750 sccm, silane flow Q SiH4=50 sccm, germane flow Q GeH4= 500 sccm hydrogen dilution ratio R= Q H2/(Q SiH4+Q GeH4)=75, discharge power W= 300 Watt and pressure P= 0.76 Torr. The deposition rate of the films was varied not monotonically in the range of Td from 70 to 300 °C. Hydrogen bonding was characterized by Fourier transform infrared (FTIR) spectroscopy. The electrical parameters were extracted from the measurements of temperature dependence of conductivity σ(T). Activation energy and room temperature conductivity of the films were observed in the range of the values E a=0.27 to 0.37 eV and σ RT=5.7 × 10 -5 to 9.6 × 10 -4 Ω -1 cm -1, respectively. The electronic properties characterized by different electrical and optical measurements showed optimal properties within the deposition temperature range T d∼160 °C to 220 °C © 2011 IEEE.
Eichelkraut T.,Friedrich - Schiller University of Jena |
Vetter C.,Friedrich - Schiller University of Jena |
Perez-Leija A.,Friedrich - Schiller University of Jena |
Moya-Cessa H.,Instituto Nacional Of Astrofsica |
And 2 more authors.
Optica | Year: 2014
Two-dimensional continuous time quantum random walks (CTQRW) are physical processes where quantum particles simultaneously evolve in different permissible directions within discrete graphs. In order to force the quantum walkers (QWs) to evolve in such a fashion, one generally requires periodic potentials. Here, we demonstrate that two-dimensional CTQRW can be generated in free space by properly tailoring the initial wave functions. We analytically show that within a certain spatial region the arising probability distribution quantitatively resembles the probability pattern exhibited by a QW traversing a periodic lattice potential. These theoretical predictions were experimentally verified using classical laser light, appropriately shaped by a spatial light modulator. Expanding the presented results to the case of multiple walkers may open new possibilities in quantum information technology using bulk optics. © 2014 Optical Society of America.
Vzquez-Snchez R.A.,University of Arts and Science of Chiapas |
Kuzin E.A.,Instituto Nacional Of Astrofsica |
Garca-Lara C.M.,University of Arts and Science of Chiapas |
May-Alarcn M.,University Autnoma Del Carmen |
And 3 more authors.
Optik | Year: 2010
A fiber laser sensor, which consists of two coupled cavities based on three fiber Bragg gratings (two of them acting as sensing elements) and is interrogated via the longitudinal mode beating frequency, is presented. The two resonant cavities have lengths of 4250 m and 4297 m, respectively. Their beating frequency is of the order of 24 kHz, and its shift as a function of the variation of the period of one (or both) of the sensing gratings, induced by strain or temperature changes, can be measured by a radio-frequency analyzer. The system is suitable for long-distance sensing with high spatial resolution and high sensitivity. © 2009 Elsevier GmbH All rights reserved.
Bon E.,Astronomical Observatory |
Bon E.,Isaac Newton Institute of Chile |
Zucker S.,Tel Aviv University |
Netzer H.,Tel Aviv University |
And 19 more authors.
Astrophysical Journal, Supplement Series | Year: 2016
We present an analysis of 43 years (1972 to 2015) of spectroscopic observations of the Seyfert 1 galaxy NGC 5548. This includes 12 years of new unpublished observations (2003 to 2015). We compiled about 1600 Hβ spectra and analyzed the long-term spectral variations of the 5100 Å continuum and the Hβ line. Our analysis is based on standard procedures, including the Lomb-Scargle method, which is known to be rather limited to such heterogeneous data sets, and a new method developed specifically for this project that is more robust and reveals a ∼5700 day periodicity in the continuum light curve, the Hβ light curve, and the radial velocity curve of the red wing of the Hβ line. The data are consistent with orbital motion inside the broad emission line region of the source. We discuss several possible mechanisms that can explain this periodicity, including orbiting dusty and dust-free clouds, a binary black hole system, tidal disruption events, and the effect of an orbiting star periodically passing through an accretion disk. © 2016. The American Astronomical Society. All rights reserved.