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Search Results: 1 - 10 of 2431 matches for " Ole Bang "
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Highly sensitive refractometer with photonic crystal fiber long-period grating
Lars Rindorf,Ole Bang
Physics , 2007, DOI: 10.1364/OL.33.000563
Abstract: We present highly sensitive refractometers based on a long-period grating in a large mode area PCF. The maximum sensitivity is 1500 nm/RIU at a refractive index of 1.33, the highest reported for any fiber grating. The minimal detectable index change is $2\times 10^{-5}$. The high sensitivity is obtained by infiltrating the sample into the holes of the photonic crystal fiber to give a strong interaction between the sample and the probing field.
Sensitivity of photonic crystal fiber grating sensors: biosensing, refractive index, strain, and temperature sensing
Lars Rindorf,Ole Bang
Physics , 2007, DOI: 10.1364/JOSAB.25.000310
Abstract: We study the sensitivity of fiber grating sensors in the applications of strain, temperature, internal label-free biosensing, and internal refractive index sensing. It is shown that optical dispersion plays a central role in determining the sensitivity, and the dispersion may enhance or suppress sensitivity as well as change the sign of the resonant wavelength shifts. We propose a quality factor, $Q$, for characterizing LPGs.
Solitons in nonlocal nonlinear media: exact results
Wieslaw Krolikowski,Ole Bang
Physics , 2000, DOI: 10.1103/PhysRevE.63.016610
Abstract: We investigate the propagation of one-dimensional bright and dark spatial solitons in a nonlocal Kerr-like media, in which the nonlocality is of general form. We find an exact analytical solution to the nonlinear propagation equation in the case of weak nonlocality. We study the properties of these solitons and show their stability.
Modulational instability in periodic quadratic nonlinear materials
J. F. Corney,Ole Bang
Physics , 2001, DOI: 10.1103/PhysRevLett.87.133901
Abstract: We investigate the modulational instability of plane waves in quadratic nonlinear materials with linear and nonlinear quasi-phase-matching gratings. Exact Floquet calculations, confirmed by numerical simulations, show that the periodicity can drastically alter the gain spectrum but never completely removes the instability. The low-frequency part of the gain spectrum is accurately predicted by an averaged theory and disappears for certain gratings. The high-frequency part is related to the inherent gain of the homogeneous non-phase-matched material and is a consistent spectral feature.
Solitons in quadratic nonlinear photonic crystals
Joel F. Corney,Ole Bang
Physics , 2000, DOI: 10.1103/PhysRevE.64.047601
Abstract: We study solitons in one-dimensional quadratic nonlinear photonic crystals with modulation of both the linear and nonlinear susceptibilities. We derive averaged equations that include induced cubic nonlinearities and numerically find previously unknown soliton families. The inclusion of the induced cubic terms enables us to show that solitons still exist even when the effective quadratic nonlinearity vanishes and conventional theory predicts that there can be no soliton. We demonstrate that both bright and dark forms of these solitons are stable under propagation.
The complete modulational instability gain spectrum of nonlinear QPM gratings
J. F. Corney,Ole Bang
Physics , 2003, DOI: 10.1364/JOSAB.21.000617
Abstract: We consider plane waves propagating in quadratic nonlinear slab waveguides with nonlinear quasi-phase-matching gratings. We predict analytically and verify numerically the complete gain spectrum for transverse modulational instability, including hitherto undescribed higher order gain bands.
Nonlocal incoherent solitons
Wieslaw Krolikowski,Ole Bang,John Wyller
Physics , 2004, DOI: 10.1103/PhysRevE.70.036617
Abstract: We investigate the propagation of partially coherent beams in spatially nonlocal nonlinear media with a logarithmic type of nonlinearity. We derive analytical formulas for the evolution of the beam parameters and conditions for the formation of nonlocal incoherent solitons.
Chromatic dispersion of liquid crystal infiltrated capillary tubes and photonic crystal fibers
Per Dalgaard Rasmussen,Jesper Laegsgaard,Ole Bang
Physics , 2006, DOI: 10.1364/JOSAB.23.002241
Abstract: We consider chromatic dispersion of capillary tubes and photonic crystal fibers infiltrated with liquid crystals. A perturbative scheme for inclusion of material dispersion of both liquid crystal and the surrounding waveguide material is derived. The method is used to calculate the chromatic dispersion at different temperatures.
Robustness of Quadratic Solitons with Periodic Gain
Lluis Torner,Juan P. Torres,Ole Bang
Physics , 2000, DOI: 10.1016/S0030-4018(00)01028-2
Abstract: We address the robustness of quadratic solitons with periodic non-conservative perturbations. We find the evolution equations for guiding-center solitons under conditions for second-harmonic generation in the presence of periodic multi-band loss and gain. Under proper conditions, a robust guiding-center soliton formation is revealed.
LARCs after unsafe abortion in Libreville (Gabon): Women accept quickly but the time interval for the insertion is longer than that of injectable contraceptives  [PDF]
Sosthène Mayi-Tsonga, Jacques Bang Ntamack, Boniface Sima-Ole, Pamphile Assoumou Obiang, Ulysse Minkobame, Doris Ngouafo
Open Journal of Obstetrics and Gynecology (OJOG) , 2014, DOI: 10.4236/ojog.2014.41005
Abstract:

Objectives: To determine the percentage of women who accepted a LARC after abortion, specify the interval time for the insertion of the LARC and compare such interval time with that of injectable and oral contraceptives. Patients and Methods: This is a prospective, descriptive and comparative study conducted in Libreville (Gabon), from February 1, 2013 to August 31, 2013. After receiving post-abortion care (PAC), all patients with stable general states were counseled about three types of contraceptive methods: combined oral contraceptive pills, LARCs (Jadelle? implants, Copper IUDs) and injectable Medroxyprogesterone Acetate (DMPA). Results: 231 women received PAC and among them 215 (93%) wanted to use one of the three proposed contraceptive methods. At the end of the study, only 193 women (89.7%) used contraception and 22 others (10.3%) abandoned their intentions. LARCs were used by 31 (16.0%) women. The average period for the insertion of LARCs was 15.4 ± 15.5 days with extremes of 1 to 53 days. This period for the insertion of LARCS was significantly longer than that of other methods (p < 0.001). LARCs were inserted more often after the 2nd day than immediately (same day) with a highly significant difference (p < 0.0001). Conclusion: LARCs could constitute an appropriate approach to reducing unintended pregnancies in Gabon. However, in order to increase their rates of use, it is necessary to improve women awareness.

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