Gedämpfter Laserverstärker und Phasenunschärfe

Damped Laser Amplifier and Phase Uncertainty In extension of a paper about the possibility to measure the phase of a microscopic field by linear amplification the damping is introduced in the linear amplifier. For this end the Fokker-Planck equation is solved and a quasiprobability distribution is obtained for an arbitrary initial state. With the help of this distribution the phase uncertainty for the largely amplified field is calculated. It is shown that appreciable damping destroys the result which was obtained for a lossless laser amplifier.     

Physikalisch-chemische Vorgänge beim Plasmaätzen mit fluorhaltigen Ätzgasen

Examples are given for three main processes determining the reactions in plasma etching:

• i The interaction between plasma particles and the surfaces of solids;
• ii The conversion of the gas composition in the plasma;
• iii The transport phenomena of reaction products in the reactor and the vacuum system.

In the glow discharge the behaviour of saturated and unsaturated perfluorocarbon gases is very similar. Both classes of compounds are converted in a few seconds in the homologous series of perfluoroalcanes up to products of high molecular weight. The main products are CF₄, C₂F₆, C₃F₈. Unsaturated compounds lead to the deposition of thin polymer films on the walls and the electrodes, whereas saturated ones are only capable of producing films on the surface of the reaction vessel. The deposition results from the recombination of free radicals arising from the plasma interactions in the gas and at the surfaces. Vice versa sputtering of polymer fragments acts on the gas composition in the plasma. Conversion processes are controled by current density and gas pressure. The cathode fall region of the discharge is found to be the zone of the highest reaction activity.