Search results for "Wavelength"
showing 10 items of 741 documents
Laser photodetachment mass spectrometry
2004
We demonstrate that the technique of laser photodetachment spectroscopy on atomic negative ions can be used as a sensitivity enhancement tool in mass spectrometry, useful for suppressing both isotopic as well as molecular isobaric interferences. In the experiment a beam of negative ions and a laser beam are merged in a collinear geometry and the wavelength of the laser is tuned across the photodetachment threshold region. Due to the large differential Doppler shifts associated with the fast moving ions of different masses, it is possible to selectively detach ions of certain isotopes while leaving others unaffected. By choosing co-propagating laser and ion beams, the heavier isotopes of an …
Site-selective luminescence study of defects. in gamma-irradiated glassy germanium dioxide
1996
Abstract Luminescence of γ-irradiated samples of GeO2 glass was studied using dye laser excitation in the wavelength region between 590 and 656 nm. An inhomogeneously broadened luminescence band with a peak around 1.86 eV, halfwidth of 0.16 eV and decay constant τ ≈ 5.1 μs was found. At temperatures below 20 K a resonance ZPL and a vibronic peak 710 cm−1 below the laser photon energy emerge when laser is tuned to energies between 1.95–1.89 eV. The site-selective luminescence spectra are qualitatively similar to those of the non-bridging oxygen hole center (NBOHC) in SiO2 glass and are attributed to NBOHC in glassy GeO2. The measured ratio between the energies of the observed local vibration…
Optical frequency domain reflectometer distributed sensing using microstructured pure silica optical fibers under radiations
2016
International audience; We investigated the capability of micro-structured optical fibers to develop multi-functional, remotely-controlled, Optical Frequency Domain Reflectometry (OFDR) distributed fiber based sensors to monitor temperature in nuclear power plants or high energy physics facilities. As pure-silica-core fibers are amongst the most radiation resistant waveguides, we characterized the response of two fibers with the same microstructure, one possessing a core elaborated with F300 Heraeus rod representing the state-of-the art for such fiber technology and one innovative sample based on pure sol-gel silica. Our measurements reveal that the Xray radiations do not affect the capaci…
Measurements of the T2K neutrino beam properties using the INGRID on-axis near detector
2012
Precise measurement of neutrino beam direction and intensity was achieved based on a new concept with modularized neutrino detectors. INGRID (Interactive Neutrino GRID) is an on-axis near detector for the T2K long baseline neutrino oscillation experiment. INGRID consists of 16 identical modules arranged in horizontal and vertical arrays around the beam center. The module has a sandwich structure of iron target plates and scintillator trackers. INGRID directly monitors the muon neutrino beam profile center and intensity using the number of observed neutrino events in each module. The neutrino beam direction is measured with accuracy better than 0.4 mrad from the measured profile center. The …
ODMR of cd impurity centers in gg irradiated BaF2crystals
1995
Abstract The magnetic circular dichroism of the optical absorption (MCD), optically detected magnetic resonance (ODMR) as well as ESR and luminescence in Cd- doped BaF2 crystals γ-irradiated at RT were investigated. MCD signals centered at 295 nm, 290 nm and 365 nm are observed, together with corresponding radiation induced optical absorption bands in the same wavelength regions. The ODMR detected in all these bands is caused by hyperfine (hf) interaction of unpaired spin with Cd− nucleus. Three types of different Cd− related defects have been separated: 1) Cd+ c, represented by the MCD of derivative type centered at 295 nm and hf constant ACd = 480 mT, 2) Cd++c -center having lowered symme…
FILTER RESPONSE OF RESONANT WAVEGUIDE DIELECTRIC GRATINGS AT PLANE-WAVE CONICAL INCIDENCE
2009
An accurate and efficient formulation is presented for the electromagnetic analysis of dielectric waveguide gratings under plane-wave conical incidence. An arbitrary number of dielectric bars can be placed inside each one-dimension periodic cell, including the effect of dielectric losses. The reflectance of a dielectric waveguide grating under conical incidence is compared with theoretical results presented by other authors, finding a very good agreement. A single-layer reflection filter has been designed centered at λ0=1.5 μm whose spectral and angular responses are shown. For this structure, the effect of the asymmetry of the distribution of the refraction index in the reflectance has bee…
Dissipative soliton resonance in a full polarization-maintaining fiber ring laser at different values of dispersion
2016
We investigated the dissipative solitons resonance in an ytterbium-doped fiber ring laser in which all the elements are polarization maintaining (PM). A semiconductor saturable absorber mirror was used as a mode-locker. The cavity included a normal dispersion single-mode fiber (SMF) and an anomalous dispersion photonic crystal fiber. The change of the length of the PM SMF allows the variation of the net-normal dispersion of the cavity in the range from 0.022 ps2 to 0.262 ps2. As the absolute value of the net-normal dispersion increases from 0.022 ps2 to 0.21 ps2, a square-shaped single pulse transformed to a single right-angle trapezoid-shaped pulse, and, at the dispersion of 0.262 ps2, to …
Wavelength-codified fiber laser hydrogen detector
2005
We report a scheme for an optical hydrogen detector that codifies the information in wavelength. The system is based on an erbium-doped fiber laser with two coupled cavities and a Palladium-coated tapered fiber within one of the laser cavities. The tapered fiber acts as the hydrogen-sensing element. When the sensing element is exposed to a hydrogen atmosphere, its attenuation decreases changing the cavity losses. This change leads the system to switch lasing from the wavelength of the auxiliary cavity to the characteristic wavelength of the cavity which contains the sensing element. The detection level can be shifted by adjusting the reflective elements of the cavity containing the sensing …
Towards CEP stable sub two cycle IR pulse compression with bulk material
2010
We demonstrate both experimentally and numerically that self-steepening during propagation in a hollow-fiber followed by linear propagation through glass in the anomalous dispersion enables pulse compression down to 1.9 cycles at 1.8 micron wavelength.
Injection-Locked Flashlamp-Pumped Dye Lasers Of Very Narrow Linewidth
1988
Very high spectral quality flashlamp-pumped dye lasers are described, in which spectral narrowing is achieved by injection-locking of pulsed amplifying cavities to the wavelength of low power single-mode cw lasers. With the help of a fast electronic stabilization of the cavity length, we obtain a reliable complete injection. Peak powers up to 12 kW in 300 ns at a bandwith of 6 MHz are achieved over a 150 nm tuning range between 572 and 722 nm. The repetition rate is 10 Hz, limited mainly by the circulating pumps. Applications of these lasers are found in high resolution coherent Raman spectroscopy and nonlinear difference frequency mixing.