The present invention relates to the field of bacteriology. Within the STI region, a germanium material is deposited adjacent an end facet of the semiconductor optical waveguide. The polymeric organic iridium compositions employed are referred to as Type organic iridium compositions and are constituted such that at least one ligand of the polymeric organic iridium compound has a number average molecular weight of 2,000 grams per mole or greater. In a further aspect, an isopressing method and mold is provided in which the cylindrical pressure bearing element thereof is provided with an enlarged end bore to form an enlarged end section in the finished ceramic tube for sealing purposes.