An optical device is described comprising at least one fiber-optic component arrange inside said device and a particular polymer composition capable of holding said optical component(s) in a predetermined position and protecting them inside said device. The polymer composition is a silicone elastomer obtained by crosslinking a mixture comprising at least one polysiloxane containing two or more hydrogen-siloxane functional groups of formula >SiH—O—, and at least one polysiloxane containing at least two vinyl groups of formula —CH═H2, where said polysiloxane are reacted in an amount such that the molar ratio between the hydrogen-siloxane groups and the vinyl groups is less than or equal to 1:1. The polymer composition has extremely low emission of hydrogen, less than 1 cm3 per kg of composition.