The extraordinary properties of second harmonic generation in negative-index metamaterials, where the Poynting vector and the wavevector have opposite directions are investigated. The "backward" phase-matching condition results in significant changes in the Manley-Rowe relations and in spatial distributions of the field intensities of the coupled waves. 0 0

The feasibility and extraordinary properties of mirrorless optical parametric oscillations in a microscopic strongly absorbing slab of negative-index metamaterial are shown. They stem from the backwardness of electromagnetic waves inherent with this type of metamaterial. © 2009 Optical Society of America OCIS codes: 190.4975, 190.4970, 160.4236, 270 BWMOPO [4], proposes independent engineering of a ͑3͒ nonlinearity through embedded, resonant, NLO centers. In the vicinity of the resonances, ͑3͒ is exceptionally strong and optical properties of the composite can be tailored by means of quantum control.Figure 1(a) depicts the coupling geometry for the proposed TWM BWMOPO. The signal h 1 at 1 with the wave vector k 1 along the z axis is a backward wave (BW); i.e., its energy flow S 1 is directed against the z axis. The signal enters the slab of length L at z = L. The slab is also illuminated by a higherfrequency PI wave h 3 traveling along the z axis. The two coupled waves with codirected k 3 and k 1 generate an idler, h 2 , at 2 = 3 − 1 , which is also assumed to be a PI wave. The idler contributes back to the signal through TWM and thus enables optical parametric amplification (OPA) at 1 through coherent energy transfer from the control field h 3 to the signal. Thus, all wave vectors are codirected along z, whereas S 1 is counterdirected to S 2 and S 3 . This is in strict contrast with the conventional optical parametric oscillator (OPO), where all energy flows and phase velocities are codirected, with the early proposed frequency-quasidegenerate TWM BWMOPO [5], and with the recent breakthrough realization of a nondegenerate TWM BWMOPO in a periodically poled crystal [6]. In the latter two cases, both the energy flow and the wave vector of one of the waves are opposite to all others. Assuming magnetic nonlinearity ͑2͒ [2,3], the equations for the signal and the idler are given byHere, h j are the magnetic components of the fields,2 , and ⌬k = k 3 − k 2 − k 1 ; ␣ j are the absorption indices. The change of h 3 along the slab is neglected, which suffices for proving the possibility of BWMOPO and for the estimate of the oscillation threshold. The depletion of the control field drops sharply outside the plasmonic resonance associated with the NI. Equation (1) exhibits three fundamental differences as compared with TWM of copropagating waves in ordinary materials; an opposite sign of 1 because of ⑀ 1 Ͻ 0, an opposite sign with ␣ 1 because S 1 is against the z axis, and the boundary conditions for h 1 to be defined at z = L, i.e., at the opposite edge of the slab as compared to h 2 . The trans-

We investigate extraordinary features of optical parametric amplification of Stokes electromagnetic waves that originate from the three-wave mixing of a backward phonon wave with negative group velocity and two ordinary electromagnetic waves. Such properties were earlier shown to exist only in plasmonic negative-index metamaterials that are very challenging to fabricate. Nonlinear optical photonic devices with properties similar to those predicted for negative-index metamaterials are proposed.

The feasibility of light-driven engineering of isolated colloidal silver nanoparticles or, alternatively, of large fractaltype aggregates comprising hundreds to thousands of nanoparticles is investigated. Control over the size and shape of such nanostructures is shown by varying the type of optical irradiation and the amount and type of stabilizing agent. Manipulation of the morphology of plasmonic nanoparticles and composites provides control their optical properties, ability to concentrate electromagnetic radiation on subwavelength scales and ability to dramatically enhance nonlinear optical processes on the nanoscale. nm 500 nmSilver nanoprism, nanopolyhedron and nanoaggregate

The article presents an overview of the theoretical and experimental work related to unmanned aerial vehicles (UAVs) motion parameters estimation based on the integration of video measurements obtained by the on-board optoelectronic camera and data from the UAV’s own inertial navigation system (INS). The use of various approaches described in the literature which show good characteristics in computer simulations or in fairly simple conditions close to laboratory ones demonstrates the sufficient complexity of the problems associated with adaption of camera parameters to the changing conditions of a real flight. In our experiments, we used computer simulation methods applying them to the real images and processing methods of videos obtained during real flights. For example, it was noted that the use of images that are very different in scale and in the aspect angle from the observed images in flight makes it very difficult to use the methodology of singular points. At the same time, the matching of the observed and reference images using rectilinear segments, such as images of road sections and the walls of the buildings look quite promising. In addition, in our experiments we used the projective transformation matrix computation from frame to frame, which together with the filtering estimates for the coordinate and angular velocities provides additional possibilities for estimating the UAV position. Data on the UAV position determining based on the methods of video navigation obtained during real flights are presented. New approaches to video navigation obtained using the methods of conjugation rectilinear segments, characteristic curvilinear elements and segmentation of textured and colored regions are demonstrated. Also the application of the method of calculating projective transformations from frame-to-frame is shown which gives estimates of the displacements and rotations of the apparatus and thereby serves to the UAV position estimation by filtering. Thus, the aim of the work was to analyze various approaches to UAV navigation using video data as an additional source of information about the position and velocity of the vehicle.