Doubly resonant optical nanoantenna arrays for polarization resolved measurements of surface-enhanced Raman scattering

We report that rhomb-shaped metal nanoantenna arrays support multiple plasmonic resonances, making them favorable bio-sensing substrates. Besides the two localized plasmonic dipole modes associated with the two principle axes of the rhombi, the sample supports an additional grating-induced surface plasmon polariton resonance. The plasmonic properties of all modes are carefully studied by far-field measurements together with numerical and analytical calculations. The sample is then applied to surface-enhanced Raman scattering measurements. It is shown to be highly efficient since two plasmonic resonances of the structure were simultaneously tuned to coincide with the excitation and the emission wave- length in the SERS experiment. The analysis is completed by measuring the impact of the polarization angle on the SERS signal.Comment: 13 pages, 5 figure

Methods and results of a search for gravitational waves associated with gamma-ray bursts using the GEO 600, LIGO, and Virgo detectors

Paper producido por "The LIGO Scientific Collaboration and the Virgo Collaboration". (En el registro se mencionan solo algunos autores de las decenas de personas que participan).In this paper we report on a search for short-duration gravitational wave bursts in the frequency range 64 Hz–1792 Hz associated with gamma-ray bursts (GRBs), using data from GEO 600 and one of the LIGO or Virgo detectors. We introduce the method of a linear search grid to analyze GRB events with large sky localization uncertainties, for example the localizations provided by the Fermi Gamma-ray Burst Monitor (GBM). Coherent searches for gravitational waves (GWs) can be computationally intensive when the GRB sky position is not well localized, due to the corrections required for the difference in arrival time between detectors. Using a linear search grid we are able to reduce the computational cost of the analysis by a factor of Oð10Þfor GBM events. Furthermore, we demonstrate that our analysis pipeline can improve upon the sky localization of GRBs detected by the GBM, if a high-frequency GW signal is observed in coincidence. We use the method of the linear grid in a search for GWs associated with 129 GRBs observed satellite-based gamma-ray experiments between 2006 and 2011. The GRBs in our sample had not been previously analyzed for GW counterparts. A fraction of our GRB events are analyzed using data from GEO 600 while the detector was using squeezed-light states to improve its sensitivity; this is the first search for GWs using data from a squeezed-light interferometric observatory. We find no evidence for GW signals, either with any individual GRB in this sample or with the population as a whole. For each GRB we place lower bounds on the distance to the progenitor, under an assumption of a fixed GWemission energy of 10−2M⊙c2, with a median exclusion distance of 0.8 Mpc for emission at 500 Hz and 0.3 Mpc at 1 kHz. The reduced computational cost associated with a linear search grid will enable rapid searches for GWs associated with Fermi GBM events once the advanced LIGO and Virgo detectors begin operation.http://journals.aps.org/prd/abstract/10.1103/PhysRevD.89.122004publishedVersionFil: Aasi, J. LIGO. California Institute of Technology; Estados Unidos de América.Fil: Domínguez, E. Argentinian Gravitational Wave Group; Argentina.Fil: Maglione, C. Argentinian Gravitational Wave Group; Argentina.Fil: Reula, O. Argentinian Gravitational Wave Group; Argentina.Fil: Ortega, W. Argentinian Gravitational Wave Group; Argentina.Fil: Wolovick, N. Argentinian Gravitational Wave Group; Argentina.Fil: Schilman, M. Argentinian Gravitational Wave Group; Argentina.Física de Partículas y Campo

Multimessenger Search for Sources of Gravitational Waves and High-Energy Neutrinos: Results for Initial LIGO-Virgo and IceCube

We report the results of a multimessenger search for coincident signals from the LIGO and Virgo gravitational-wave observatories and the partially completed IceCube high-energy neutrino detector, including periods of joint operation between 2007-2010. These include parts of the 2005-2007 run and the 2009-2010 run for LIGO-Virgo, and IceCube's observation periods with 22, 59 and 79 strings. We find no significant coincident events, and use the search results to derive upper limits on the rate of joint sources for a range of source emission parameters. For the optimistic assumption of gravitational-wave emission energy of $10^{-2}$\,M$_\odot$c$^2$ at $\sim 150$\,Hz with $\sim 60$\,ms duration, and high-energy neutrino emission of $10^{51}$\,erg comparable to the isotropic gamma-ray energy of gamma-ray bursts, we limit the source rate below $1.6 \times 10^{-2}$\,Mpc$^{-3}$yr$^{-1}$. We also examine how combining information from gravitational waves and neutrinos will aid discovery in the advanced gravitational-wave detector era

Erforschung spezieller Halbleitersysteme. Kooperation mit dem IOFFE-Institut (PTI) St. Petersburg, Russland Abschlussbericht

Aim of the project between Laser Zentrum Hannover e.V. and IOFFE-Institute (PTI) St. Petersburg was the setup of a cooperation in the field of diode laser development and the retain of production technology of diode lasers in Russia. During the project aluminium-free high power diode lasers at a wavelength of 810 nm have been developed. These diode lasers were optimized for longitudinal pumping of solid state lasers. The output power and efficiency of the developed aluminium-free laser diodes are comparable to diode lasers consisting of Ga-Al-As. The long time stability of the aluminium-free diode laser is strongly enhanced comparing with the ordinary devices. Different designs of single mode diode lasers are investigated for application in laser measurement technology. The detection of molecules, like pollution gases NO_2, CO, CO_2, H_2S, NH_3 and O_2 or H_2O, should be possible with these diode lasers by spectroscopic indication. By using of external resonator designs longitudinal single-mode operation and a clear reduction of linewidth have been demonstrated. The results show a successful improvement of quality of diode lasers by controlling the important process parameters. (orig.)Available from TIB Hannover: F95B837+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Grundlagenuntersuchung zur Konzeptionierung, Aufbau und Charakterisierung Laserdioden neuartiger Bauform im Wellenlaengenbereich um 0.8#mu#m, 1.3#mu#m und 1.5#mu#m. Kooperation mit dem IOFFE-Institut (PTI) St. Petersburg, Russland -Laser Zentrum Hannover e.V Abschlussbericht

The goal of the collaboration between the Laser Zentrum Hannover e.V. and the IOFFE Institute (PTI) St. Petersburg was to cooperate in the field of diode laser development, and to help establish semiconductor technology as a key technology in Russia. Aluminium-free high power diode lasers in the wavelength range around 970 nm were developed, to be optimized for the excitation of solid-state lasers such as Cr"4"+:YAG and Er:YAG lasers. Based on aluminium-free laser materials, structures could be realized which are comparable to Gallium-Aluminium-Arsenide (GaAlAs) diodes, concerning output power and efficiency. For laser-based metrology applications, single-mode diode lases with a wavelength from 670 nm to 1.58 #mu#m were conceived. Laser diodes with wavelengths no longer produced by commercial manufactures were also developed. These wavelengths, however, are relevant for scientific research. Investigations on AR coating of partially AR coated laser diodes were carried out using these laser diodes in continuous, tuneable external resonators without mode-hopping. The quality of the laser diodes was continuously improved. Based on the existing cooperation, a scientific exchange between the IOFFE Institute and Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V., Institut fuer Physik der Atmosphaere, Wessling concerning the supplying of laser diodes with special wavelengths could be established. (orig.)Available from TIB Hannover: F96B1161+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

NIR-Diodenlasersystem mit externem Resonator. Teilvorhaben: Untersuchung der Grundlagen eines NIR-Laserspektrometers mit schmalbandiger Wellenlaengenabstimmung Abschlussbericht

The scientific goal of the project was the investigation of the basic principles of a broadly tunable laser diode spectrometer with a narrow linewidth, enabling an effective and simple gas analysis in process gas monitoring and environmental technique. The design of the spectrometer occurs on the basis of commercially available anti-reflection coated VIS- and NIR-laser diodes operating in external resonators. Particularly with the realized different grating resonators, the results of our theoretical investigation concerning mode hop free tuning ranges could be verified. By using these optimized configurations mode hop free tuning ranges across the whole gain region of the laser diodes could be realized. Furthermore, the properties of a spectrometer with a high output power was determined. In order to qualify the spectrometer, absorption measurements of selected gases has been performed. In addition, the basic principles of anti-reflection coatings for laser diodes were investigated. By using a special simulation code, an optimization of the coating parameters could be achieved. By this means, high quality coatings with different materials could be realized. (orig.)SIGLEAvailable from TIB Hannover: F98B896+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Grundlagen zur fasergepumpten Stab- und Slablasern hoher Strahlqualitaet Abschlussbericht

In the beginning of this project the advantages of diode-pumped solid-state lasers with regard to efficiency and reliability were well known. But in the high output power range thermo-optical effects in the laser medium prevented the transformation into industrial products because of limiting the achievable beam qualities. Objective of this project was therefore to quantify these effects and to investigate possibilities to avoid or compensate them. Fiber-coupled diode lasers were used in order enable the examination of various pumping geometries in a flexible way. A numerical model was developed which correctly describes the thermo-optic effects in real laser media. Through the combination of experiments and numerical simulations the realisation of laser systems with output powers up to 750 W cw with 13% optical-to-electrical efficiency was possible. Moreover up to 80 W of output power in transverse fundamental mode operation was demonstrated. (orig.)SIGLEAvailable from TIB Hannover: F98B199+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Femtosecond Enhancement Cavities in the Nonlinear Regime

We combine high-finesse optical resonators and spatial-spectral interferometry to a highly phase-sensitive investigation technique for nonlinear light-matter interactions. We experimentally validate an ab initio model for the nonlinear response of a resonator housing a gas target, permitting the global optimization of intracavity conversion processes like high-order harmonic generation. We predict the feasibility of driving intracavity high-order harmonic generation far beyond intensity limitations observed in state-of-the-art systems by exploiting the intracavity nonlinearity to compress the pulses in time

Yb:YAG Innoslab amplifier: efficient high repetition rate subpicosecond pumping system for optical parametric chirped pulse amplification

We report on a Yb:YAG Innoslab laser amplifier system for generation of subpicsecond high energy pump pulses for optical parametric chirped pulse amplification (OPCPA) at high repetition rates. Pulse energies of up to 20 mJ (at 12.5 kHz) and repetition rates of up to 100 kHz were attained with pulse durations of 830 fs and average power in excess of 200 W. We further investigate the possibility to use subpicosecond pulses to derive a stable continuum in a YAG crystal for OPCPA seeding