Electro-optical apparatus includes a housing having at least one electrical subassembly (ESA) and at least one optical subassembly (OSA) therein as well as cavities within the housing and paths for transmitting electrical signals between the electrical and optical subassemblies. A glob top material is applied on at least a part of said paths, and hardened mass of a liquid electromagnetic absorber material at least partly fills the cavities in the housing. The hardened absorber material provides radiation absorption for the electro-optical apparatus and the glob top material protects the transmission paths from the absorber material, thereby avoiding undesired absorption of useful signals.