Laser-induced nanopatterning of PET using a-SiO2 microspheres

A regular lattice of SiO₂ microspheres on a quartz support is used as a microlens array for laser-induced nanopatterning of polyethylene terephthalate foils. Received: 2 January 2002 / Accepted: 6 January 2002 / Published online: 27 March 2002     

Fermion families and chirality through extra dimensions

We give a simple model to explain the origin of fermion families and chirality through the use of a domain wall-anti-domain wall pair placed in a five dimensional space-time. Received: 14 March 2002 / Revised version: 3 July 2002 / Published online: 27 September 2002 RID="a" ID="a" e-mail: erdem@likya.iyte.edu.tr     

Coherent switching of semiconductor resonator solitons

We demonstrate the switching on and off of spatial solitons in a semiconductor microresonator by injection of light coherent with the background illumination. The results give evidence that the formation of the solitons and their switching are not limited by thermal processes. Received: 11 February 2002 / Revised version: 25 April 2002 / Published online: 8 August 2002     

Laser operation and Raman self-frequency conversion in Yb:KYW microchip laser

We present a diode-pumped Yb:KYW microchip laser. The passive Q-switchedand CW regimes of operation for the Yb:KYW microchip laser have been investigated. An efficiency for CW operation of up to 10% with regard to incident pump has been obtained. Raman self-frequency conversion in the Q-switched regime has been observed. Received: 27 May 2002 / Revised version: 4 July 2002 / Published online: 15 November 2002 RID="*" ID="*"Corresponding author. Fax: +375-17/2840-879, E-mail: asg@dragon.bas-net.by     

150-times phase conjugation by degenerate four-wave mixing in a continuous-wave Nd:YVO4 amplifier

The high phase-conjugate reflectivity of 150, by four-wave mixing in a diode-pumped Nd:YVO₄, has been demonstrated. The phase-conjugate mirror was capable of correcting the phase aberration of a probe beam. The experimental diffraction efficiency of the transmission gratings was 60. Received: 8 April 2002 / Revised version: 10 June 2002 / Published online: 25 September 2002 RID="*" ID="*"Corresponding author. Fax: +81/43-290-3490, E-mail: omatsu@image.tp.chiba-u.ac.jp     

Resonances and spectral properties of detuned OPOs pumped by fluctuating sources

Twin-beam fluctuations are analyzed for detuned and mismatched OPO configurations. Resonances and frequency responses to the quantum noise sources (quantum and pump amplitude/phase fluctuations) are examined as functions of cavity decay rates, excitation parameters and detuning. The dependence of self- and mutual correlations of beam amplitudes and phases on detuning, mismatch and damping parameters is discussed. Received: 25 January 2002 / Revised version: 28 May 2002 / Published online: 15 November 2002 RID="*" ID="*"Corresponding author. Fax: +39-81/676-346, E-mail: alberto.porzio@na.infn.it     

A hierarchical phase space generator for QCD antenna structures

We present a ”hierarchical” strategy for phase space generation in order to efficiently map the antenna momentum structures, typically occurring in QCD amplitudes. Received: 4 April 2002 / Revised version: 6 June 2002 / Published online: 20 September 2002 RID="a" ID="a" e-mail: andrevh@inp.demokritos.gr RID="b" ID="b" e-mail: Costas.Papadopoulos@cern.ch     

Observation of light filaments induced in air by visible picosecond laser pulses

We report the observation of light filaments produced by a picosecond laser pulse in the visible. The pulse trapped in the filamentary mode experiences large-scale self-phase modulation, with almost 100-fold spectral broadening along with apparent shortening of the leading edge. Spatial-temporal properties of the light filament reveal rather complex propagation dynamics. Received: 7 August 2002 / Revised version: 12 September 2002 / Published online: 11 December 2002 RID="*" ID="*"Corresponding author. Fax: +370-2/3660-06, E-mail: audrius.dubietis@ff.vu.lt     

\eta_b decay into two photons

We discuss the theoretical predictions for the two photon decay width of the pseudoscalar meson. Predictions from potential models are examined. It is found that various models are in good agreement with each other. Results for are also compared with those from data through the NRQCD procedure. Received: 28 July 2002 / Revised version: 16 September 2002 / Published online: 20 November 2002     

Statistical modeling of imaging process in active night vision systems with gate-light detection

Characteristics of object images observed through scattering media with an active vision system operating in the mode of spatial selection are estimated using the Monte Carlo method. The effect of optical and geometrical conditions of observation on the contrast in images of reflecting objects is considered. Interpretation is given to the obtained dependences. Received: 11 February 2002 / Revised version: 31 May 2002 / Published online: 25 October 2002 RID="*" ID="*"Corresponding author. Fax: +7-38/2225-9086, E-mail: belov@iao.ru     

Ordered thin films of alkyloxy-substituted benzaldehydes on a graphite surface studied by scanning tunneling microscopy

The molecular assembly of three different trialkyloxy-substituted benzaldehydes on graphite has been studied using scanning tunneling microscopy (STM). It is found that these benzaldehydes, which do not have intermolecular hydrogen bonding, could form a lamella arrangement in which the headgroups are aligned side by side. The effect due to the alkyl chain length on the lamella structure is also presented. Received: 21 January 2002 / Accepted: 22 March 2002 / Published online: 10 September 2002 RID="*" ID="*"Corresponding author. Fax: +86-10/6255-7908     

Random deflection of the white light beam during self-focusing and filamentation of a femtosecond laser pulse in water

Ti:sapphire femtosecond laser pulse filamentation in competition with optical breakdown in condensed matter is studied both experimentally and numerically using water as an example. Strong random deflection and modulation of the supercontinuum under tight focusing conditions were observed. They manifest the beginning of the filamentation process near the highly disordered plasma created by optical breakdown at the geometrical focus. Received: 13 June 2002 / Revised version: 16 August 2002 / Published online: 25 October 2002 RID="*" ID="*"Corresponding author. Fax: +1-418/656-2623, E-mail: wliu@phy.ulaval.ca     

Simultaneous measurement of absolute OH concentration,temperature and flow velocity in a flame by photothermal deflection spectroscopy

We demonstrate the use of photothermal deflection spectroscopy for a simultaneous measurement of absolute minority-species concentration, temperature and flow velocity in a flame from the analysis of a single data trace. The ability to make absolute concentration measurements, as well as the ability to measure three important combustion parameters simultaneously, may make this technique quite useful in many circumstances. Received: 27 August 2002 / Revised version: 26 September 2002 / Published online: 11 December 2002 RID="*" ID="*"Corresponding author. Fax: +1-479/575-4580, E-mail: rgupta@uark.edu     

One loop scalar functions in the heavy-quark effective theory

We find general solutions for the dimensionally regularized scalar one-loop three-point and four-point functions with one heavy-quark propagator. The scalar one-point function vanishes, while the expression for the two-point function has been found before. For the latter we give a detailed derivation. We also discuss some special cases and compile useful formulae. Received: 15 February 2002 / Revised version: 15 April 2002 / Published online: 12 July 2002     

Present knowledge of atomic masses

Progress is reviewed of available data for evaluation of atomic masses since the 1995 one. Many more direct mass measurements have become available, especially in the region of proton-rich nuclides. The number of alpha- and, especially, proton-decay data increased considerably. In the region of superhigh mass numbers, many very interesting new observations were made. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: wapstra@nikhef.nl     

Particle on a conical surface

The motion of a particle on the conical surface interacting with a scalar and a vector potential is studied in the path integral framework following the technique of constraints. The propagators are evaluated taking into account the problem of the angle periodicity. The result is given in a compact form. Received: 10 April 2002 / Revised version: 2 September 2002 / Published online: 25 October 2002     

Bichromatic pulsed source in the visible and infrared

A source of bichromatic coherent radiation is described with independent tunability in wavelength, energy and pulse duration. The system is able to deliver pulses in the visible to infrared region with possible extension into the ultraviolet. Pulse durations can be tailored to be from 15 ps to 310 fs with collimated beam fluences of several mJ/cm². Received: 28 January 2002 / Revised version: 24 April 2002 / Published online: 12 July 2002     

Diffractive heavy vector meson production from the BFKL equation

Diffractive heavy vector meson photoproduction accompanied by proton dissociation is studied for arbitrary momentum transfer. The process is described by the non-forward BFKL equation, for which a complete analytical solution is found, giving the scattering amplitude. The impact of non-leading corrections to the BFKL equation is also analysed. Results are compared to the HERA data on production. Received: 2 July 2002 / Revised version: 29 August 2002 / Published online: 18 October 2002     

Lasers in nuclear physics --A review

Lasers have played an important role for the development of new spectroscopy techniques yielding spins, electromagnetic moments and charge radii of many unstable nuclei. More recently, similar techniques have been introduced to manipulate atoms and thus to prepare beams or samples of radioactive atoms for various applications including nuclear spectroscopy and decay studies. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: rainer.neugart@uni-mainz.de     

100-W average-power, high-energy nanosecond fiber amplifier

We report on the fiber-based amplification of a Q-switched Nd:YAG thin-disk laser. At repetition rates between 3 and 50 kHz output powers up to 100 W are generated. Pulse energies up to 4 mJ, with diffraction-limited beam quality, are generated in a 30-μm Yb-doped large-mode-area fiber, furthermore pulse energies up to 8 mJ are achieved from a multimode fiber amplifier. Received: 8 May 2002 / Revised version: 10 July 2002 / Published online: 25 October 2002 RID="*" ID="*"Corresponding author. Fax: +49-3641/65-7680, E-mail: Jens.Limpert@uni-jena.de