Atomic force microscope tip spontaneous retraction from dielectric surfaces under applied electrostatic potential.

A time-resolved method for tip' retraction at micros-scale away from dielectric surfaces has been developed. Analysis of the forces in the system comprising AFM tip, water meniscus, and polymer film suggests that an electrostatic repulsion of the tip from the surface in the double-layered (water and polymer) system, and water condensation in the tip-surface junction are the dominant factors enabling the mechanical work for tip retraction. Nanostructures of 5-80 nm height are formed in polymeric surfaces as a result. This interesting physical phenomenon could be used for nanostructures patterning in polymeric materials at enhanced aspect ratio.

Spectral equalization and autosweeping effects in a pulsed dye laser with an intracavity photorefractive element.

A pulsed dye laser with an intracavity photorefractive element is reported. It is shown that the element can be used for storage of spectral information. New effects for this system such as spectral equalization and oscillation-frequency autosweeping are demonstrated.

Three-wave and four-wave forward phase-conjugate imaging in photorefractive bismuth silicon oxide.

Phase-conjugate images in the forward direction are obtained by a new type of four-wave interaction and by the Heer-Griffin type of three-wave interaction. The nonlinear medium is bismuth silicon oxide in which the interaction is optimized by detuning the input beam(s). Measurements are made for several test objects and interbeam angles.