Search results for "Toe"
showing 10 items of 3824 documents
Time-Domain Integration of Terahertz pulses
2021
We report on the time-domain integration of terahertz pulses obtained via the tight confinement of the radiation in a tapered two-wire waveguide. Both simulation and experimental results prove the time integration capability of this structure.
CSRZ-ASK and DPSK 40 Gb/s All-Raman WDM Transmission Based on UltraWave Fiber
2006
In this paper, we report a complete experimental and numerical analysis of 40 Gb/s WDM ultra long-haul (ULH) transmission using CSRZ-DPSK and CSRZ-ASK modulation formats on UltraWavetrade fiber spans. Experimental results compare well with full numerical simulations
The RICH counter in the CERN hyperon beam experiment
1992
Abstract The hyperon beam experiment WA89 at the CERN-SPS uses a ring imaging Cherenkov counter (RICH) for identification of secondaries from ∑ − N reactions. Cherenkov photons are generated in a 5 m long radiator volume filled with nitrogen at atmospheric pressure and detected in drift chambers. The drift chambers cover an active surface of 1.6 × 0.75 m 2 , with a maximum drift path of 41 cm. Photoelectrons are counted on 1280 wires with a pitch of 2.54 mm, equipped with multihit TDCs. The counting gas is ethane saturated with TMAE at 30°C. The counter was operated in two beam periods in 1990 and 1991. The spatial resolution of the chambers is better than 2 mm and under normal running cond…
Charge measurement of dust particles on photovoltaic module
2013
Photovoltaic (PV) systems are one of the most promising renewable energy sources in the world, and hence it is important to explore the factors that affect the working / operational efficiency of this source. Many factors can affect the efficiency of the solar cells such as: dust accumulation on the surface of the arrays; cell material; shading; tilt angle of the cells; orientation of the PV modules and cell temperatures. This research is focused on the analyzing the effect of charged dust particles on the PV module performance. A number of studies have demonstrated the effect of dust accumulation on the PV modules' performance. But the relation between the amounts of charge of the dust par…
THE LIMITING EFFICIENCY OF FOUR-BAND CELLS REVISITED
2014
The limiting theoretical efficiency of four-band solar cells is revisited. In previous work, researchers have looked at the theoretical efficiency of four band cells where the smallest of the three sub-band gaps is closest to the valence band and the largest closest to the conduction band. In this work, limits are calculated also for other possible band configurations. In multi-band cells, photon selectivity can be assured by adjusting the band widths. The present work shows that previous authors have put too rigid constraints on the band structure to achieve spectral selectivity. Relieving these constraints gives a considerably higher limiting efficiency for cells with band width restricti…
Electronic structure of the spin-12quantum magnet TiOCl
2005
We have studied the electronic structure of the spin-$1∕2$ quantum magnet TiOCl by polarization-dependent momentum-resolved photoelectron spectroscopy. From that, we confirm the quasi-one-dimensional nature of the electronic structure along the crystallographic $b$ axis and find no evidence for sizable phonon-induced orbital fluctuations as the origin for the noncanonical phenomenology of the spin-Peierls transition in this compound. A comparison of the experimental data to our own $\mathrm{LDA}+\mathrm{U}$ and Hubbard model calculations reveals a striking lack of understanding regarding the quasi-one-dimensional electron dispersions in the normal state of this compound.
Characterization of Al-Schottky CdTe detectors
2011
In the last decades, great efforts are being devoted to the development of CdTe detectors for high resolution X-ray and gamma ray spectroscopy. Recently, new rectifying contacts based on aluminum (Al) are very appealing in the development of CdTe detectors with low leakage currents and anode pixellization. In this work, we report on preliminary results of electrical and spectroscopic investigations on Schottky CdTe diode detectors (4.1 × 4.1 × 0.75 and 4.1 × 4.1 × 2 mm3) with Au/Ti/Al/CdTe/Pt electrode configuration. The detectors are characterized by very low leakage currents even at room temperature (26 pA at 25 °C under a bias voltage of −100 V for the 2 mm thick detector). Polarization …
Kerr frequency comb generation in the normal dispersion regime of dispersion oscillating telecom fiber
2013
The generation of optical frequency combs has a variety of applications from optical metrology to spectroscopy and wavelength division multiplexing. Nonlinear methods to generate frequency combs are based on multiple four-wave mixing (FWM) in highly nonlinear waveguides [1]. The mechanism for the generation of a wideband comb from a CW pump is Kerr-induced phase-matching of the FWM interaction or modulation instability (MI), which requires operating in the anomalous dispersion regime. Such restriction can be circumvented with a cavity geometry, where MI [2] and comb generation [3] may also be observed in the normal dispersion region. Alternatively, one may obtain MI and unequally spaced Ker…
High repetition rates and high quality optical pulse train generator based on solitons over finite background
2013
This work proposes to fully exploit the nonlinear evolution undergone by a sinusoidal modulation with a finite background propagating along an optical fiber. For the original method to overcome this major drawback is to exploit the π phase shift that exists between the pulsed part and the background. By using a simple delay-line interferometer, it is possible to simultaneously double the repetition rate of the pulse train and to annihilate the deleterious background by imprinting a controlled π phase shift.
All-optical fiber-based amplitude jitter magnifier
2010
International audience; We describe the concept of an all-fibered device that enables the optical magnification of the amplitude jitter of low-fluctuation pulse trains, facilitating the measurement of the statistical properties by usual photodiodes and electronic equipments. Taking advantage of a highly nonlinear fiber with anomalous dispersion followed by central optical bandpass filtering, we experimentally demonstrate an amplification of small-scale fluctuations by a factor 10.