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41.
We theoretically predict and numerically demonstrate that narrow beams (of the width of few wavelengths) can be efficiently parametrically amplified in nonlinear photonic crystal (with chi((2)) nonlinearity) tuned to sub-diffractive (self-collimating) regimes. We derive relations and give analytic estimations for the efficiency of amplification. 相似文献
42.
Anatoly M. Zyakun Artem I. Muravyev Boris P. Baskunov Kestutis S. Laurinavichius Vladimir N. Zakharchenko Valentina P. Peshenko 《Isotopes in environmental and health studies》2013,49(1):78-90
Using a theoretical model and mass isotopic balance, biogas (methane and CO2) released from buried products at their microbial degradation was analysed in the landfill of municipal and non-toxic industrial solid organic waste near Kaluga city, Russia. The landfill contains about 1.34×106 tons of waste buried using a ‘sandwich technique’ (successive application of sand–clay and waste layers). The δ13C values of biogenic methane with respect to CO2 were?56.8 (±2.5) ‰, whereas the δ13C of CO2 peaked at+9.12‰ (+1.4±2.3‰ on average), reflecting a virtual fractionation of carbon isotopes in the course of bacterial CO2 reduction at the landfill body. After passing through the aerated soil layers, methane was partially oxidised and characterised by δ13C in the range of?50.6 to?38.2‰, evidencing enrichment in 13C, while the released carbon dioxide had δ13C of?23.3 to?4.04‰, respectively. On the mass isotopic balance for the δ13C values, the methane production in the landfill anaerobic zone and the methane emitted through the aerated landfill surface to the atmosphere, the portion of methane oxidised by methanotrophic bacteria was calculated to be from 10 to 40% (averaged about 25%). According to the theoretical estimation and field measurements, the annual rate of methane production in the landfill reached about 2.9(±1.4)×109 g C CH4 yr?1 or 5.3(±2.6)×106 m3 CH4 yr?1. The average rates of methane production in the landfill and methane emission from landfill to the atmosphere are estimated as about 53 (±26) g C CH4 m?2 d?1 (or 4 (±2) mol CH4 m?2 d?1) and 33 (±12) g C CH4 m?2 d?1 (or 2.7 (±1) mol CH4 m?2 d?1), respectively. The calculated part of methane consumed by methanotrophic bacteria in the aerated part of the landfill was 13(±7) g C CH4 m?2 d?1 (or 1.1(±0.6) mol CH4 m?2 d?1) on average. 相似文献
43.
44.
We propose a nonlinear all-photonic-crystal (PhC) Fabry-Perot cavity tuned to the subdiffractive regime of the interior PhC, and we study angular-resolved nonlinear propagation of monochromatic plane wave excitations. With rigorous numerical simulations, we show that, for sufficiently large negative pump detunings and a focusing nonlinearity, the transmitted field has a bistable dependence on the pump field. Moreover, we reveal that, in contrast to a homogeneous resonator for different inclinations, the hysteresis curve is virtually unchanged for a fairly wide angular range. This may pave the way for obtaining novel kinds of nonlinear localized solutions in driven nonlinear resonators. 相似文献
45.
We investigate band-gap solitons, i.e. the solitons in Kerr-nonlinear media with periodic in space modulation of potential, and show that they are unstable for their eigenfrequencies around the middle of the band-gap, i.e. radiate into mode continua of the upper and lower bands. We identify the mechanism of four-wave mixing that causes the radiation of solitons. We also show that the gap solitons self-stabilize by losing their mass due to the radiation and thus recoil into the non-radiative area of the band-gap. 相似文献
46.
Aidas K Kongsted J Osted A Mikkelsen KV Christiansen O 《The journal of physical chemistry. A》2005,109(35):8001-8010
The combined linear response coupled cluster/molecular mechanics (CC/MM) scheme including mutual polarization effects in the coupling Hamiltonian is applied together with supermolecular CC methods to the study of the gas-to-aqueous solution blue shift of the n --> pi* excitation energy in acetone. The aug-cc-pVDZ basis set is found to be adequate for the calculation of this excitation energy. In the condensed phase, the shift in the excitation energy is obtained by statistical averaging over 800 solute-solvent configurations extracted from a molecular dynamics simulation. We find the shift to be around 1100-1200 cm(-1) depending on the specific model used to describe solvent polarization. The importance of including explicit polarization in both the molecular dynamics simulation as well as the CC/MM calculations is emphasized. Furthermore, the significant dependence of the excitation energy on the CO bond length of acetone is discussed. 相似文献
47.
Temporal periodic modulation of the interatomic s-wave scattering length in Bose-Einstein condensates is shown to excite subharmonic patterns in the atom density through a parametric resonance. The dominant wavelength of the spatial structures is primarily selected by the excitation frequency but also affected by the depth of the spatial modulation via a nonlinear resonance. These phenomena represent analogues of the Faraday patterns excited in vertically vibrated liquids. 相似文献
48.
Staliunas K 《Physical review letters》2003,91(5):053901
We show dissipative spatial solitons in nonlinear optical microresonators in which the refractive index is laterally modulated. In addition to "normal" and "staggered" dissipative solitons, similar to those in spatially modulated conservative systems, a narrow "midband" soliton is shown, having no counterparts in conservative systems. 相似文献
49.
We present a qualitative study of the subdiffractive light beam propagation in photonic crystals, based on the theoretical analysis of full Maxwell equation system beyond the slowly varying envelope and paraxial approximations. We calculate the zero diffraction curve in the parameter space, we calculate the weak asymptotical broadening (spreading in transverse direction), and we also analyze the dependence of subdiffractive propagation on the polarization orientation (both for TM and TE polarization). 相似文献
50.
We experimentally demonstrate the stripe (or roll) patterns in a broad-aperture degenerate optical parametric oscillator in a plane-mirror minicavity. The stabilization of stripes is achieved by seed injection at a subharmonic frequency. We measure the temporal spectra of the stripe pattern and obtain the 1/f-like noise spectra. 相似文献