Alkoxide-based precursors for direct drawing of metal oxide micro- and nanofibres.

The invention of electrospinning has solved the problem of producing micro- and nanoscaled metal oxide fibres in bulk quantities. However, until now no methods have been available for preparing a single nanofibre of a metal oxide. In this work, the direct drawing method was successfully applied to produce metal oxide (SnO, TiO, ZrO, HfO and CeO) fibres with a high aspect ratio (up to 10 000) and a diameter as small as 200 nm.

Bessel-Gauss pulse as an appropriate mathematical model for optically realizable localized waves.

We show that the field of the optically feasible luminal localized wave solutions of the scalar homogeneous wave equation can be modeled by means of Bessel-Gauss pulses. As the Bessel-Gauss pulses have a closed-form expression, this fact may be of great value in numerical simulations of various experimental situations.

Generation and classification of localized waves by Lorentz transformations in Fourier space.

The Lorentz transformations of propagation-invariant localized waves (also known as nondispersive or nondiffracting or undistorted progressive waves) are studied in the frequency-momentum space. For supports of wave functions in this space rules of transformation are derived which allow one to group all localized waves into distinct classes: subluminal, luminal, and superluminal localized waves. It is shown that for each class there is an inertial frame in which any given localized wave takes a particularly simple form.

Experimental demonstration of realizability of optical focus wave modes.

The homogeneous scalar wave equation has a number of so-called localized wave (LW) solutions, instantaneous, Gaussian pulselike intensity distribution of which propagates without any spread or distortions in free space. Despite the undoubtedly intriguing properties and considerable effort that has been made to implement such wave fields, in the optical domain only their limiting case-the so-called Bessel-X pulses-has been experimentally launched so far. In this paper we report on experimental evidence of the optical realizability of the "fundamental" special case of the LW's-the focus wave modes.

Optically realizable localized wave solutions of the homogeneous scalar wave equation.

One of the most frequently discussed problems in construction of localized wave (LW) solutions of the homogeneous scalar wave equation has been their energy content--the LW's generally have infinite energy content and special methods have to be used to obtain physically realizable wave fields. So far the problem has mainly been addressed as a pure mathematical one and the proposed LW's can hardly be implemented in optics. In this paper we propose an approach for constructing physically realizable LW's that have a transparent interpretation in terms of optical setups.

Self-imaging of three-dimensional images by pulsed wave fields.

Recently, the classical Talbot effect (self-imaging of optical wave fields) has attracted a renewed interest, as the concept has been generalized to the domain of pulsed wave fields by several authors. In this paper we discuss the self-imaging of three-dimensional images. We construct pulsed wave fields that can be used as self-imaging "pixels" of a three-dimensional image and show that their superpositions reproduce the spatial separated copies of its initial three-dimensional intensity distribution at specific time intervals.