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Search Results: 1 - 10 of 534709 matches for " A. Tünnermann "
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High dispersive and monolithic 100% efficiency grisms
J. Reinhold,M. Schulze,E. -B. Kley,A. Tünnermann
Physics , 2012,
Abstract: We present a type of grism, a series combination of transmission grating and prism, in which we reduce the number of diffraction orders and achieve a configuration with very high angular dispersion. The grism can be fabricated from a single dielectric material and requires no metallic or dielectric film layers for high transmission diffraction efficiency. One can reach 100% in the -1st transmission diffraction order and the equal damage threshold as the dielectric bulk material. We realized such an element in fused silica with an efficiency of more then 99%. The bevel backside reflection is reduced by a statistical antireflective structure, so we measured an efficiency of the entire grism of 95% at a single wavelength.
Diffractive Optics for Gravitational Wave Detectors
A. Bunkowski,O. Burmeister,K. Danzmann,R. Schnabel,T. Clausnitzer,E. -B. Kley,A. Tünnermann
Physics , 2007, DOI: 10.1088/1742-6596/32/1/051
Abstract: All-reflective interferometry based on nano-structured diffraction gratings offers new possibilities for gravitational wave detection. We investigate an all-reflective Fabry-Perot interferometer concept in 2nd order Littrow mount. The input-output relations for such a resonator are derived treating the grating coupler by means of a scattering matrix formalism. A low loss dielectric reflection grating has been designed and manufactured to test the properties of such a grating cavity.
Optical characterization of ultra-high diffraction efficiency gratings
A. Bunkowski,O. Burmeister,T. Clausnitzer,E. -B. Kley,A. Tünnermann,K. Danzmann,R. Schnabel
Physics , 2007, DOI: 10.1364/AO.45.005795
Abstract: We report on the optical characterization of an ultra-high diffraction efficiency grating in 1st order Littrow configuration. The apparatus used was an optical cavity built from the grating under investigation and an additional high reflection mirror. Measurement of the cavity finesse provided precise information about the grating's diffraction efficiency and its optical loss. We measured a finesse of 1580 from which we deduced a diffraction efficiency of (99.635$\pm$0.016)% and an overall optical loss due to scattering and absorption of just 0.185 %. Such high quality gratings, including the tool used for their characterization, might apply for future gravitational wave detectors. For example the demonstrated cavity itself presents an all-reflective, low-loss Fabry-Perot resonator that might replace conventional arm cavities in advanced high power Michelson interferometers.
Optical coupling of fundamental whispering gallery modes in bi-spheres
L. I. Deych,C. Schmidt,A. Chipouline,T. Pertsch,A. Tünnermann
Physics , 2007, DOI: 10.1103/PhysRevA.77.051801
Abstract: What will happen if two identical microspheres, with fundamental whispering gallery modes excited in each of them, become optically coupled? Conventional wisdom based on coupled-mode arguments says that two new modes, bonding and anti-bonding, with two split frequencies would be formed. In this paper we demonstrate, using exact multi-sphere Mie theory, that in reality an attempt to couple two fundamental modes of microspheres would result in a complex multi-resonance optical response with the field distribution significantly deviating from predictions of coupled-mode type theories.
Asymmetric transmission of linearly polarized light at optical metamaterials
C. Menzel,C. Helgert,C. Rockstuhl,E. -B. Kley,A. Tünnermann,T. Pertsch,F. Lederer
Physics , 2010, DOI: 10.1103/PhysRevLett.104.253902
Abstract: We experimentally demonstrate a three-dimensional chiral optical metamaterial that exhibits an asymmetric transmission for forwardly and backwardly propagating linearly polarized light. The observation of this novel effect requires a metamaterial composed of three-dimensional chiral metaatoms without any rotational symmetry. Our analysis is supported by a systematic investigation of the transmission matrices for arbitrarily complex, lossy media that allows deriving a simple criterion for asymmetric transmission in an arbitrary polarization base. Contrary to physical intuition, in general the polarization eigenstates in such three-dimensional and low-symmetry metamaterials do not obey fxed relations and the associated transmission matrices cannot be symmetrized.
La calidad de la educación superior y su acreditación: la experiencia centroamericana
Tünnermann Bernheim, Carlos;
Avalia??o: Revista da Avalia??o da Educa??o Superior (Campinas) , 2008, DOI: 10.1590/S1414-40772008000200005
Abstract: this chapter presents a comparative study of the accreditation processes in central america and of the institutions that are responsible for developing them.
América Latina: identidad y diversidad cultural. El aporte de las universidades al proceso integracionista
Carlos Tünnermann Bernheim
Polis : Revista de la Universidad Bolivariana , 2007,
Abstract: En este artículo se analiza el proceso de formación de la nacionalidad latinoamericana, así como las pistas que ayuden a descubrir las características de nuestra identidad, reconociendo el mestizaje como definitorio de nuestro ser y quehacer como latinoamericanos. Se advierten las potencialidades que se desprenden de la riqueza que significa la diversidad étnica y cultural de la región. La integración de América Latina es vista como un reto que nuestros pueblos deben asumir, partiendo de una concepción que supere la visión puramente economicista y se afirme en la dimensión humana y solidaria. Finalmente se examinan las tareas que las universidades deberían asumir para contribuir a hacer realidad ese desafío, tales como auspiciar estudios e investigaciones interdisciplinarias sobre las posibilidades de dise ar un proyecto latinoamericano de Desarrollo Humano, Endógeno y Sostenible, además de contribuir a crear una conciencia integracionista y establecer institutos de estudios latinoamericanos, entre otros aspectos.
La autonomía universitaria en el contexto actual
Carlos Tünnermann Bernheim
Universidades , 2008,
La aotonomía universitaria frente al mundo globalizado
Carlos Tünnermann Bernheim
Universidades , 2006,
El constructivismo y el aprendizaje de los estudiantes
Carlos Tünnermann Bernheim
Universidades , 2011,
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