Über die endlichen Ringe mit gegebener additiver Gruppe

Ohne Zusammenfassung     

Über die Realisierbarkeit eines Laser-gepumpten parametrischen Mikrowellen-Verstärkers

Summary The realizability of a parametric microwave amplifier with a laser-pumped electrooptic crystal as a nonlinear element is investigated theoretically for ideal and lossy crystals. It is found that even with the best presently available crystals a 10-db-travelling wave amplifier needs a pump power flux of the order of 10⁷W/cm². Consequentlycw-operation is impossible. Phase matching can be achieved either by a suitable choice of the propagation directions or by increasing the phasevelocity of the signal with a waveguide. Both possibilities are treated. With given parameters of the nonlinear material, the formulas and graphs permit a quick estimation of the required pump power and the proper crystal- and waveguide dimensions. Finally the introduction of a resonator at signal frequency is being considered. However, it is found, that only a small amount of pump power can be saved, as even with low resonatorQ the amplitude fluctuations of the pump deteriorate the gain stability very much. With high resonatorQ a parametric oscillator is obtained.

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Gewidmet Herrn Professor Dr. K. P. Meyer zu seinem 60. Geburtstag     

Über die Anzahl Abelscher Gruppen gegebener Ordnung. I

Ohne Zusammenfassung