Dichroic Beam-splitters for High-power Copper Vapour Lasers

Abstract

Abstract A methodology for the design of dichroic beam splitters for high-power copper vapour lasers is presented. The increased damage resistance should result as a consequence of the suppression of the standing-wave electric field peaks in the multilayer stack. For a conventional dichroic beam splitter, the admittance locus at a passband wavelength is in the form of a spiral which moves outwards as a pair of layers of the basic stack is deposited, thus resulting in the appearance of peaks in the electric field distribution wherever, for a given layer, the admittance is real and minimum. These peaks can be suppressed by identifying a starting point on the admittance diagram in such a manner that, starting from this point, the admittance locus for each repeating pair of layers does not spread outwards but retraces onto itself. The substrate is then matched with this starting point by a suitable combination of two or more layers of the same materials used for the multilayer stack. This index matching also ...