Do columnar defects produce bulk pinning?

From magneto-optical imaging performed on heavy-ion-irradiated YBa(2)Cu(3)O(7-delta) single crystals, it is found that at fields and temperatures where strong single vortex pinning by individual irradiation-induced amorphous columnar defects is to be expected, vortex motion is limited by the nucleation of vortex kinks at the specimen surface. In the material bulk, vortex motion occurs through (easy) kink sliding. Depinning in the bulk determines the screening current only at fields comparable to or larger than the matching field, at which the majority of vortices is not trapped by an ion track.     

Generation of radially polarized terahertz pulses via velocity-mismatched optical rectification

We demonstrate the generation of radially polarized terahertz pulses via optical rectification in a Cherenkov geometry exploiting velocity mismatch, contrary to the traditional approach for generating linearly polarized terahertz beams. A compact system is implemented using 001-cut ZnTe pumped by an ultrafast Yb-doped fiber amplifier.     

Copper vapor laser with intracavity radiation scanning by a spatial and temporal light modulator based on PLZT ceramics

The results of an experimental study of the output radiation parameters of a copper vapor laser (CVL) with a self-conjugate resonator are presented. TheQ-factor was controlled by diaphragms (slit or circular) and spatial and temporal light modulators (STLM) based on PLZT ceramics.