Abstract: A method for detecting faulty laying down of an optical cable exhibiting a measured cut-off wavelength includes providing an optical cable for transmitting optical signals including at least one single-mode optical fiber having an attenuation equal to or larger than a first threshold value as measured when wound for one turn around a bending radius equal to or smaller than 5 mm at at least one predetermined test wavelength, the test wavelength being smaller than the measured cut-off wavelength, and an attenuation smaller than a second threshold value as measured when wound for one turn around a bending radius equal to at least a minimum bending radius at an operative wavelength equal to or larger than the measured cut-off wavelength; laying the optical cable; and measuring the attenuation in the at least one optical fiber at the predetermined test wavelength.

Abstract: A method for detecting faulty laying down of an optical cable exhibiting a measured cut-off wavelength includes providing an optical cable for transmitting optical signals including at least one single-mode optical fibre having an attenuation equal to or larger than a first threshold value as measured when wound for one turn around a bending radius equal to or smaller than 5 mm at at least one predetermined test wavelength, the test wavelength being smaller than the measured cut-off wavelength, and an attenuation smaller than a second threshold value as measured when wound for one turn around a bending radius equal to at least a minimum bending radius at an operative wavelength equal to or larger than the measured cut-off wavelength; laying the optical cable; and measuring the attenuation in the at least one optical fibre at the predetermined test wavelength.

Abstract: An intermediate polymer preform of elongated shape for manufacturing a microstructured optical fibre is made from a mould with a tubular par containing a pattern of hole generating elements (wires, rods or tubes) extending along it. The hole generating elements are releasably attached to an upper and to a lower base of the mould. The mould is cleaned by circulating a filtered solvent in it. The mould is filled with a fluid polymer optical material or polymer precursor. The polymer material or precursor is consolidated so that it cannot change its shape under operating stress conditions at ambient temperature. The hole generating elements are released from the upper and lower base. The consolidated core preform is extracted from the mould. The process can further include calibrating the intermediate preform.

Abstract: An intermediate polymer preform of elongated shape for manufacturing a microstructured optical fibre is made from a mould with a tubular par containing a pattern of hole generating elements (wires, rods or tubes) extending along it. The hole generating elements are releasably attached to an upper and to a lower base of the mould. The mould is cleaned by circulating a filtered solvent in it. The mould is filled with a fluid polymer optical material or polymer precursor. The polymer material or precursor is consolidated so that it cannot change its shape under operating stress conditions at ambient temperature. The hole generating elements are released from the upper and lower base. The consolidated core preform is extracted from the mould. The process can further include calibrating the intermediate preform.