Ergodic BSDEs and related PDEs with Neumann boundary conditions under weak dissipative assumptions

We study a class of ergodic BSDEs related to PDEs with Neumann boundary conditions. The randomness of the drift is given by a forward process under weakly dissipative assumptions with an invertible and bounded diffusion matrix. Furthermore, this forward process is reflected in a convex subset of $\R^d$ not necessary bounded. We study the link of such EBSDEs with PDEs and we apply our results to an ergodic optimal control problem

Magnetic field dependence of up-converted photoluminescence in partially ordered GaInP{sub 2}/GaAs up to 23 T

The influence of a strong magnetic field on the up-converted photoluminescence (PL) spectra of partially ordered layers of GaInP{sub 2} grown on GaAs substrate have been investigated. The up-converted PL spectra exhibit 2 peaks. The position of the low energy peak is close to that of the peak observed in Pl spectra excited by above GaInP{sub 2} bandgap light while the other peak occurs at about 30 meV higher in energy. Both peaks show a linear dependence on B between 0 and 23 T suggesting that free carriers with effective masses of 0.084 m{sub 0} and 0.24m{sub 0} (m{sub 0} is the free electron mass) are involved in these transitions. They interpret the low energy peak as originating from the recombination of localized holes with free electrons while the high energy peak is related to the recombination of localized electrons with free holes

Selenium Molecules And Their Possible Role In Deep Emission From Glasses Doped With Selenide Nanocrystals

We report the observation of Raman scattering from a vibration mode with frequency of 320 cm-1 and its higher-order harmonics in silicate glasses doped with selenide semiconductor nanocrystals such as CdSe and ZnSe. Comparison with Raman spectra of glasses and alkali halides doped with Se suggests that these modes are caused by the presence of selenium molecules in the glasses. When excited in the blue and green by an Ar+ laser, glasses containing Se only are found to emit strong near-infrared luminescence whose peak and line shape are very similar to the so-called "deep emission" observed frequently from selenide-doped glasses. Possible effects of Se molecules on the linear and nonlinear optical properties of glasses containing selenide nanocrystals are discussed. © 1996 American Institute of Physics.80210541057Yoffe, A.D., (1993) Adv. Phys., 42, p. 173Beadie, G., Lawandy, N.M., (1995) Opt. Lett., 20, p. 2153Gomes, A.S.L., Dearaujo, C.B., Miliou, A., Srivastava, R., (1993) Electron. Lett., 29, p. 1246Flytzanis, C., Hache, F., Klein, M.C., Richard, D., Roussignol, P., (1991) Progress in Optics, 29. , North-Holland, AmsterdamWilliams, V.S., Olbright, G.R., Fluegel, B.D., Koch, S.W., Peyghambarian, N., (1988) J. Mod. Opt., 35, p. 1979Krull, M., Coutaz, J.-L., (1990) J. Opt. Soc. Am. B, 7, p. 1463. , and references thereinLiu, L.C., Risbud, S.H., (1990) J. Appl. Phys., 68, p. 28Baganich, A.A., Mikla, V.I., Semak, D.G., Sokolov, A.P., Shebanin, A.P., (1991) Phys. Status Solidi, 166, p. 297Griffiths, J.E., Malyj, M., Espinosa, G.P., Remeika, J.P., (1984) Phys. Rev. B, 30, p. 6978Leite, R.C.C., Scott, J.F., Damen, T.C., (1969) Phys. Rev. Lett., 22, p. 780Scott, J.F., Leite, R.C.C., Damen, T.C., (1969) Phys. Rev., 188, p. 1285Martin, T.P., (1976) Phys. Rev., 13, p. 3617Fabian, H., Fischer, F., (1989) J. Raman Spectrosc., 20, p. 515Rebane, L.A., Khaldre, T.Yu., (1977) JETP Lett., 26, p. 51Holtzer, W., Murphy, W.F., Bernstein, H.J., (1969) J. Mol. Spectrosc., 32, p. 13Fabian, H., Fischer, F., (1989) J. Lumin., 43, p. 103Wang, L.S., Niu, B., Lee, Y.T., Shirley, D.A., (1989) Chem. Phys. Lett., 158, p. 1297Yee, K.K., Barrow, R.F., (1972) J. Chem. Soc. Faraday Trans. II, 68, p. 118

Laser-induced Heating Of Nanocrystals Embedded In Glass Matrices

Laser-induced heating of nanocrystals embedded in silicate glass matrices has been studied by photoluminescence and Raman scattering. No nonequilibrium optical phonons were found both for cw and 150-ps-long laser pulses in contrast to bulk samples. The measured laser-induced I temperature rise in one sample where the nanocrystal radii are ∼5 nm was found to be in quantitative agreement with a nonlinear theory proposed by Lax for bulk semiconductors. However, in another sample where the nanocrystal radii are only 3 nm, the observed temperature rise at high laser powers was significantly higher than the theoretical prediction. © 1996 American Institute of Physics.801059635966Asada, M., Migamoto, Y., Suematsu, Y., (1986) IEEE J. Quantum Electron., QE-22, p. 1915Hoyer, P., Könenkamp, R., (1995) Appl. Phys. Lett., 66, p. 349Yoffe, A.D., (1993) Adv. Phys., 42, p. 173Shah, J., (1992) Hot Carriers in Semiconductor Nanostructures, Physics and Applications, , Academic, New YorkLax, M., (1977) J. Appl. Phys., 48, p. 3919(1978) Appl. Phys. Lett., 33, p. 786Dobal, P.S., Bist, H.D., Mehta, S.K., Jain, R.K., (1994) Appl. Phys. Lett., 65, p. 2469Duval, E., Boukenter, A., Champagnon, B., (1986) Phys. Rev. Lett., 56, p. 2052Tanaka, A., Onari, S., Arai, T., (1993) Phys. Rev. B, 47, p. 1237Liu, L.C., Risbud, S.H., (1990) J. Appl. Phys., 68, p. 28Rodrigues, P.A.M., Tamulaitis, G., Yu, P.Y., Risbud, S.H., (1995) Solid State Commun., 94, p. 583Borrelli, N.F., Hall, D.W., Holland, H.J., Smith, D.W., (1987) J. Appl. Phys., 61, p. 5399Tu, A., Persans, P.D., (1991) Appl. Phys. Lett., 58, p. 1506Logothetidis, S., Cardona, M., Lautenschlager, P., Garriga, M., (1986) Phys. Rev. B, 34, p. 2458Nomura, S., Kobayashi, T., (1992) Phys. Rev. B, 45, p. 1305Malhotra, J., Hagan, D.J., Potter, B.G., (1991) J. Opt. Soc. Am. B, 8, p. 1531Roussignol, J., Ricard, D., Lukasik, J., Flytzanis, C., (1987) J. Opt. Soc. Am. B, 4, p. 5Kim, D.S., Yu, P.Y., (1991) Phys. Rev. B, 43, p. 4158Mattos, J.C.V., Leite, R.C.C., (1973) Solid State Commun., 12, p. 465Babcock, C.L., (1977) Silicate Glass Technology, , Wiley, New YorkAmmar, M.M., Gharib, S.A., Halawa, M.M., El-Batal, H.A., El-Badry, K., (1983) J. Am. Ceram. Soc., 66, pp. C76Touloukian, Y.S., Thermophysical Properties of Matter (1970) The Thermophysical Properties Research Center Data Series. Vol. 2. Thermal Conductivity-Non-metallic Solids, 2, p. 933. , Plenum, New YorkKapitza, P.L., (1941) J. Phys., 4, p. 181. , Mosco

Relations between parameters of fracture processes on different scale levels

© 2018, Pleiades Publishing, Ltd. Abstract: The processes of ultrasonically-assisted drilling (UAD) and the dynamic tests on split Hopkinson pressure bar (SHPB), fracture in which is implemented at various structural-scale levels, are considered. The simulation of UAD based on the Hertz contact problem and the structural−time criterion is presented. The problem of using the value of the fracture incubation time and its linear size obtained from the tests on SHPB in the simulation is considered. A principle of equal power is used for converting the strength parameters into another structural−scale level. The theoretical curve obtained in the simulation is compared with the results of experiments on conventional drilling (CD) and UAD

Interaction potential between dynamic dipoles: polarized excitons in strong magnetic fields

The interaction potential of a two-dimensional system of excitons with spatially separated electron-hole layers is considered in the strong magnetic field limit. The excitons are assumed to have free dynamics in the $x$-$y$ plane, while being constrained or `polarized' in the $z$ direction. The model simulates semiconductor double layer systems under strong magnetic field normal to the layers. The {\em residual} interaction between excitons exhibits interesting features, arising from the coupling of the center-of-mass and internal degrees of freedom of the exciton in the magnetic field. This coupling induces a dynamical dipole moment proportional to the center-of-mass magnetic moment of the exciton. We show the explicit dependence of the inter-exciton potential matrix elements, and discuss the underlying physics. The unusual features of the interaction potential would be reflected in the collective response and non-equilibrium properties of such system.Comment: REVTEX - 11 pages - 1 fi

Quantum Maxwell-Bloch equations for spatially inhomogeneous semiconductor lasers

We present quantum Maxwell-Bloch equations (QMBE) for spatially inhomogeneous semiconductor laser devices. The QMBE are derived from fully quantum mechanical operator dynamics describing the interaction of the light field with the quantum states of the electrons and the holes near the band gap. By taking into account field-field correlations and field-dipole correlations, the QMBE include quantum noise effects which cause spontaneous emission and amplified spontaneous emission. In particular, the source of spontaneous emission is obtained by factorizing the dipole-dipole correlations into a product of electron and hole densities. The QMBE are formulated for general devices, for edge emitting lasers and for vertical cavity surface emitting lasers, providing a starting point for the detailed analysis of spatial coherence in the near field and far field patterns of such laser diodes. Analytical expressions are given for the spectra of gain and spontaneous emission described by the QMBE. These results are applied to the case of a broad area laser, for which the frequency and carrier density dependent spontaneous emission factor beta and the evolution of the far field pattern near threshold are derived.Comment: 22 pages RevTex and 7 figures, submitted to Phys.Rev.A, revisions in abstract and in the discussion of temporal coherenc

Electron Spin Decoherence in Bulk and Quantum Well Zincblende Semiconductors

A theory for longitudinal (T1) and transverse (T2) electron spin coherence times in zincblende semiconductor quantum wells is developed based on a non-perturbative nanostructure model solved in a fourteen-band restricted basis set. Distinctly different dependences of coherence times on mobility, quantization energy, and temperature are found from previous calculations. Quantitative agreement between our calculations and measurements is found for GaAs/AlGaAs, InGaAs/InP, and GaSb/AlSb quantum wells.Comment: 11 pages, 3 figure