Streuung elektromagnetischer Oberflächen- und Volumenwellen an rauhen Oberflächen. Teil I. Allgemeine Grundlagen

Scattering of Electromagnetic Surface and Bulk Waves from Rough Surfaces. Part I. General Theory A classical theory of scattering of electromagnetic surface and bulk waves on rough surfaces (dielectrics or conductors) is given. The primary wave creates a surface polarization on the rough boundary presenting the source for the radiation of scattering. These roughness-caused polarization must be considered in the wave equations and in the boundary conditions of the fields, too. General expressions for the spectral power density of surface and bulk scattering waves will be given. The excitation of surface polarization can result from primary waves homogenously or inhomogenously.     

The Time-space-dependent Power Spectrum for the Description of Nonstationary and Inhomogeneous Electromagnetic Fields

The nonstationary analogue to the stationary Wiener Khintchine theorem is considered and applied to the multi-dimensional case of temporally nonstationary and spatially inhomogeneous electromagnetic fields. The time-space-dependent power spectrum of these fields is introduced, and its connection with important measurable quantities is discussed. The dispersions relations (the mutual dependence of the Fourier variables ω, k belonging to the time and space coordinates t, ??) are included into the consideration. The variable Fourier amplitudes are compared with the conventionally used slowly varying field amplitudes. The transition to the stationary limiting case is carried out.     

TE mode photon echo in slab waveguides

A theory of TE mode photon echo in slab waveguides is developed. It is found that the conditions for generation of a photon echo in waveguides can substantially differ from those in bulk material. For the photon echo in waveguides there is an optimum value of the Rabi frequency, and the echo energy does not depend periodically on the Rabi frequency as in the case of bulk material photon echo. Moreover, it is shown that the capability for echo generation is different for different modes. In particular there are several modes in the waveguide which cannot, in principle, generate an echo.     

Streuung elektromagnetischer Oberflächen- und Volumenwellen an rauhen Oberflächen. Teil II. Die Streulichtverteilung; Ein- und Auskopplung von Oberflächenwellen

Scattering of Electromagnetic Surface and Bulk Waves from Rough Surfaces. Part II. The Indicatrix of Scattering; the Coupling of Surface and Bulk Waves In this paper, we present the calculation of the spectral power density of light scattered from homogenously isotropic and rough surfaces which are influenced by bulk or surface waves. A classification of all possible scattering cases in dependence on the wave types which arise in the regions z > O and z < O is given. The dependence of scattered light on scattering angles for the different possibilities of polarisation variantes (∥ and ?) will be presented. The relationship between the correlation function of roughness and the efficiency of coupling between bulk and surface modes will be discussed and compared with the results of other authors.     

Theorie der nichtstationären Anregung von Exziton-Polaritonen durch Zweiphotonenabsorption

Theory of nonstationary Exciton-Polariton Generation by Two-photon Absorption A theory of nonstationary two-photon absorption for nonlinear non-centrosymmetric crystals is presented. The time-dependent radiation flux density of the generated polariton beam is calculated under the condition of an ultrashort laser pulse duration T_L ? ΓT^?1 (ΓT is the exciton line width) and a stationary incoherent test field. The “mechanical” response of the excitons and different group velocities of the polariton and the laser and test fields are taken into account. the spatial dispersion of the exciton motion being neglected. With a rectangular laser pulse shape the analytically nonstationary solutions are discussed for identical and for different group velocities of laser and test fields. Using the conservation laws for energy and quasimomentum we illustrate, by considering the polariton dispersion branches, the various possible cases of two-photon absorption in uniaxial piezocrystals.     

Mechanistic Studies on the Organocatalytic α‐Chlorination of Aldehydes: The Role and Nature of Off‐Cycle Intermediates

Herein we report the isolation and characterization of aminal intermediates in the organocatalytic α‐chlorination of aldehydes. These species are stable covalent ternary adducts of the substrate, the catalyst and the chlorinating reagent. NMR‐assisted kinetic studies and isotopic labeling experiments with the isolated intermediate did not support its involvement in downstream stereoselective processes as proposed by Blackmond. By tuning the reactivity of the chlorinating reagent, we were able to suppress the accumulation of rate‐limiting off‐cycle intermediates. As a result, an efficient and highly enantioselective catalytic system with a broad functional group tolerance was developed.     

Theoretical Treatment of Nonstationary Scattering by Phonons and Polaritons Part II. Transient Raman Scattering by Polaritons and Dipole Active Phonons

The stimulated Raman scattering by polaritons and phonons generated by the fluctuations of the crystal vibrations is investigated for the transient regime. The transient gain and the scattering energy is given for the case of retarded or advanced Stokes and polariton pulses in relation to the laser pulse. Moreover, the influence of phase modulation of the laser pulse on the transient SRS by polaritons is discussed.     

Solitonen in Wellenleitern mit nichtlinearer optischer Beschichtung

Solitons in a Waveguide with a Thin Nonlinear Optical Slab Starting from Maxwell's equations the influence of a thin nonlinear optical slab embed in a waveguide on the propagation of a monomode (TE) pulse is investigated. The amplitude of the pulse is described by a nonlinear Schrödinger equation (NLS) containing parameters of the waveguide with the nonlinear slab and leading to solitons in the nonlinear modified waveguide.     

Eine neue Methode zur Bestimmung der Rauhigkeitsautokorrelationsfunktion von optischen Oberflächen

A New Method of Determining the Autocorrelation Function of Polished Optical Surfaces Starting with a general theory of light scattering a measuring procedure for determining the autocorrelation function of surface roughness of well polished substrates is deduced. In this method light intensity scattered into a fixed direction has to be measured in dependence on the dimensions of the scattering area. The results are tested for a glass surface polished by different methods.