Laser-induced diffraction patterns in germanium diselenide amorphous films.
We report the characterization of changes produced on germanium diselenide amorphous semiconductor thin films by a focused He-Ne laser beam. The diffraction pattern produced by the laser spot on the sample is studied as a function of the intensity and the irradiation time. At low intensities the state of polarization of the incident beam generates an asymmetry in the induced diffraction pattern. Moreover, if the polarization of the incident beam is rotated, the corresponding asymmetry rotates as well. These results show the difference between thermal and electromagnetic effects on the material. This system may be used as a high density recording medium.
Thickness dependence of the phase conjugate signal of amorphous selenium thin films
Abstract The dependence of the phase conjugate (PC) signal on the thickness of the nonlinear medium has been studied for amorphous selenium thin film samples, in the range from 1500 to 48000 A. The experiments were performed using a degenerate four wave mixing (DFWM) scheme. The PC signal increases with thickness of the sample in the 1500–15000 A range, for thicker samples the PC signal reaches a saturation value. The results are analyzed using a DFWM model in absorbing media. A novel theoretical treatment where the effect of reflection at the air-film interface plays a dominant role yields good agreement with the experimental data.
The REX-ISOLDE project
The Radioactive Beam Experiment REX-ISOLDE [1–3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy, astrophysics and solid state physics will be addressed by REX-ISOLDE.