Comparison of diffraction patterns exposed by pulsed and CW lasers on positive-tone photoresist.

Two different grating formation geometries for recording onto the positive-tone photoresist with pulsed laser and continuous-wave sources are analyzed and compared. Diffraction efficiency measurements and atomic force microscopy (AFM) examination have been performed in order to investigate the optical and topographical properties of the recorded structures. Gratings patterned by a continuous-wave laser and by a pulsed laser working in the single pulse and multipulse regimes showed different surface roughness and optical properties.

Rectified oscillatory motion of the self-ordered front under zero-mean ac force: role of symmetry of the rate function.

The rectified oscillatory motion of the "bistable" fronts (BFs) joining two states of the different stability in a spatially extended system with two stable equilibria is studied by use of the macroscopic kinetic equation of the reaction-diffusion type. The adiabatic approximation is used: We assume that the period of the ac force acting on the front in the system significantly exceeds the characteristic relaxation time of the system. By using the arguments based on the symmetry properties of the rate function in the governing equation of the ac driven front, we show that a close corelation (one-to-one correspondence) between the rate functions of the different symmetry, the symmetrical and asymmetrical ones, and the response functions performing the "input-output" conversion between the oscillatory forcing (input) function and the speed (output) function, which describes the temporal oscillations of the moment velocity of the ac driven BF, exists.

Unidirectional drift of bistable front under asymmetrically oscillating zero-mean force.

The unidirectional drift of bistable fronts (BFs) that separate two stable uniform states of a bistable system under the action of an asymmetrically oscillating zero-mean force (driver) is considered within the "pseudolinear" (piecewise-linear) model of the system. The particular case of the symmetrical (symmetrically shaped) rate functions is studied. To perform a rigorous analytic treatment for arbitrary strengths of the driving force we assume that the applied ac force is quasistatically slow.

Unidirectional drift of fronts under zero-mean force, and broken symmetries of the rate function.

The deterministic front-ratchet effect, namely, the unidirectional transport of the bistable fronts (BFs) under the additive zero-mean ac forcing, is considered within the piecewise-linear model of the bistable system. Two different mechanisms underlying the front ratchet, two cases of the broken symmetry of (i) the rate function, and/or (ii) the external zero-mean ac forcing are analyzed. Types of unidirectional motion, some versions of the "unforced" migration of BFs, are found in both cases of the travelling (initially propagating) and the static (motionless) fronts.