Optical fibre feedthrough with bi-directional sealing using axial seals

An optical waveguide feedthrough assembly 900 passes at least one optical waveguide 922 through a bulk head, a sensor wall, or other such member. The waveguide assembly comprises a cane-based optical waveguide, having a first section 920 of larger diameter than a second section. The shouldered plug thus formed is sealingly disposed in the feedthrough housing. Seals 931,932 fill an annular space between the thicker section of the waveguide and the housing. The seal may be energized by a fluid pressure in the housing to establish sealing engagement. Further, the seal may provide bidirectional sealing. The sealing arrangements may include a containment member (713) having features that mate with the profile of the waveguide element. The sealing arrangement may also comprise a plurality of v-ring seals (630). The feedthrough assembly is operable in high temperature and high pressure environments.