Abstract
In a wideband communications system with optical switching a space division switching unit based on lithium-niobate matrices is used. Such matrices need light of a defined state of polarisation that will be provided via polarization maintaining fibers. These fibers are directly glued to the laser crystal so that the linearly polarized light of the laser matches one of their principal axes as exactly as possible. The influence of an angular mismatch on this coupling is calculated and a criterion for adjustment is determined. This gluing will alter the power balance of the laser and its P-I-characteristic, which is calculated in an appendix. With these formulas the laser-fiber coupling loss will be determined.