PROCESS FOR MANUFACTURING A MICRO-STRUCTURED OPTICAL FIBRE

摘要

Forming an intermediate polymer preform of elongated shape for manufacturing a microstructured optical fibre can comprise: making a mould with a tubular par (21) containing a pattern of hole generating elements (23) (wires, rods or tubes) extending along it, the hole generating elements being releasably attached to an upper (25) and to a lower (22) base of the mould; cleaning the mould by circulating a filtered solvent in it; filling the mould with a fluid polymer optical material or polymer precursor; consolidating the polymer material or precursor so that it cannot change its shape under operating stress conditions at ambient temperature: releasing the hole generating elements from the upper and lower base; extracting the consolidated core preform from the mould and, if required, extracting the hole-generating elements from the core preform (40), in order to create the microstructure. The process can further include calibrating the intermediate preform, wherein calibrating comprises: stretching the intermediate preform during a stretching period by heating it (51) at a predetermined stretching temperature avove Tg and applying a tensional load (F) to the intermediate preform (50) along its elongation axis, so as to cause its straining along the elongation axis, the stetching temperature, the tensional laod and the stretching period being selected so as to impress a viscoelastic deformation to the intermediate preform; cooling the intermediate preform to a temperature below Tg during a cooling period, while maintaining the stretched preform in tension, so as to avoid a substantial release of said viscoelastic deformation; inserting the intermediate preform in a calibration tube (53) having a cylindrical inner shape; and heating (52) the intermediate polymer preform to a calibration temperature above Tg during a calibration period sufficient to achieve a substantial release of said viscoelastic deformation.