Search results for "PTO"
showing 10 items of 28599 documents
A universal optical all-fiber omnipolarizer
2012
International audience; Wherever the polarization properties of a light beam are of concern, polarizers and polarizing beamsplitters (PBS) are indispensable devices in linear-, nonlinear- and quantum-optical schemes. By the very nature of their operation principle, transformation of incoming unpolarized or partially polarized beams through these devices introduces large intensity variations in the fully polarized outcoming beam(s). Such intensity fluctuations are often detrimental, particularly when light is post-processed by nonlinear crystals or other polarization-sensitive optic elements. Here we demonstrate the unexpected capability of light to self-organize its own state-of-polarizatio…
Simultaneous polarization attraction and Raman amplification of a light beam in optical fibers
2012
International audience; In this paper, we demonstrate that it is possible to combine both Raman amplification and polarization attraction of a signal wave in a single optical fiber by means of a counterpropagating scheme. Experiments were performed near 1550 nm in a continuous wave regime and by means of a 10 Gbit ∕ s return-to-zero signal injected in a 20 kmlong low polarization mode dispersion optical fiber. Complete repolarization and 6.7 dB amplification of the signal wave was achieved by injecting a 850 mW, 1480 nm counterpropagating polarized pump wave.
Near‐IR Radiation‐Induced Attenuation of Aluminosilicate Optical Fibers
2021
The X-ray radiation-induced attenuation (RIA) growth kinetics are studied online in different single-mode aluminosilicate optical fibers in the near-IR (NIR) domain to evaluate their potential in terms of dosimetry. The optical fibers differ by Al contents, core sizes, drawing parameters, and also by a preform deposition process. The data show no dependence of the RIA on all these parameters, a positive result for the design of point or distributed radiation detectors exploiting RIA to monitor the dose. The RIA growth rate is unchanged for dose rates changing from 0.073 to 6.25 Gy(SiO2) s−1, and the RIA linearly increases with the dose up to 2 kGy(SiO2). Small but noticeable RIA changes are…
Ge quantum well plasmon-enhanced quantum confined Stark effect modulator
2014
ABSTRACTWe theoretically and experimentally investigate a novel modulation concept on silicon (Si) based on the combination of quantum confinement and plasmon enhancement effects. We experimentally study the suitability of Ge/SiGe quantum wells (QWs) on Si as the active material for a plasmon-enhanced optical modulator. We demonstrate that in QW structures absorption and modulation of light with transverse magnetic (TM) polarization are greatly enhanced due to favorable selection rules. Later, we theoretically study the plasmon propagation at the metal-Ge/SiGe QW interface. We design a novel Ge/SiGe QW structure that allows maximized overlap between the plasmonic mode and the underlying Ge/…
Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition.
2013
A study of transmittance and photoluminescence spectra on the growth of oxygen-rich ultra-thin ZnO films prepared by atomic layer deposition is reported. The structural transition from an amorphous to a polycrystalline state is observed upon increasing the thickness. The unusual behavior of the energy gap with thickness reflected by optical properties is attributed to the improvement of the crystalline structure resulting from a decreasing concentration of point defects at the growth of grains. The spectra of UV and visible photoluminescence emissions correspond to transitions near the band-edge and defect-related transitions. Additional emissions were observed from band-tail states near th…
Optical and structural properties of Al 2 O 3 /ZnO nanolaminates deposited by ALD method
2014
International audience; We report on the investigation of optical and structural properties of Al2O3/ZnO nanolaminates. The nanolaminates were deposited on Si and glass substrates by Atomic layer deposition method. Structural properties of nanolaminates were studied by SEM, GIXRD, and AFM. Optical characterization was performed by transmittance and photoluminescence spectroscopy. Complex analysis of monolayer properties was done by ellipsometry. Optical constants for Al2O3 and ZnO monolayer were calculated.
FREE SPACE OPTICS LINKS AFFECTED BY OPTICAL TURBULENCE: CHANNEL MODELING, MEASUREMENTS AND CODING TECHNIQUES FOR ERROR MITIGATION
2014
FSO is an optical wireless line-of-sight communication system able to offer good broadband performance, electromagnetic interference immunity, high security, license-free operation, low power consumption, ease of relocation, and straightforward installation. It represents a modern technology, significantly functional when it is impossible, expensive or complex to use physical connections or radio links. Unfortunately, since the transmission medium in a terrestrial FSO link is the air, these communications are strongly dependent on various atmospheric phenomena (e.g., rain, snow, optical turbulence and, especially, fog) that can cause losses and fading. Therefore, in worst-case conditions, i…
Optimización del tratamiento de daptomicina mediante índices farmacocinéticos y farmacodinámicos
2023
La antibioterapia óptima implica la utilización del régimen de dosificación del antimicrobiano adecuado para conseguir los mejores resultados clínicos con los mínimos efectos adversos para el paciente y el mínimo impacto en el desarrollo de resistencias. Con el fin de conseguir estos resultados en los tratamientos con daptomicina en la práctica clínica, se ha desarrollado un modelo farmacocinético/farmacodinámico de daptomicina, cuyo objetivo es seleccionar las pautas de administración más adecuadas para cada paciente de acuerdo con la sensibilidad del microorganismo causal de la infección garantizando la consecución de los parámetros farmacocinético/farmacodinámico objetivo (área bajo la c…
Unravelling the Intertwined Atomic and Bulk Nature of Localised Excitons by Attosecond Spectroscopy
2021
The electro-optical properties of most semiconductors and insulators of technological interest are dominated by the presence of electron-hole quasi-particles, called excitons. The manipulation of excitons in dielectrics has recently received great attention, with possible applications in different fields including optoelectronics and photonics. Here, we apply attosecond transient reflection spectroscopy in a sequential two-foci geometry and observe sub-femtosecond dynamics of a core-level exciton in bulk MgF2 single crystals. Furthermore, we access absolute phase delays, which allow for an unambiguous comparison with theoretical calculations. Our results show that excitons surprisingly exhi…
Low dimensional perovskite: synthetic methods and application in optoelectronics
2020
Through the end of contribute to the next generation of photovoltaics and light emitting devices the preparation of no-expensive and high quality materials with high PLQY and reduced non-radiative recombination is crucial. For such a reason the thesis is focus on the develop of high optoelectronic potential hybrid perovskite material and on their processing methods. In the different Chapters, various low dimensional perovskite synthetic approaches and their application are investigated. In the Chapter 2, a low dimension quasi-2D perovskite with a remarkable PLQY was prepared thanks to interplay of different fabrication approaches such us altered stoichiometry, solution engineered deposition…