Abstract: The present invention relates to a method for manufacturing a preform for optical fibers, which method comprises the sequential steps of: i) deposition of non-vitrified silica layers on the inner surface of a hollow substrate tube; ii) deposition of vitrified silica layers inside the hollow substrate tube on the inner surface of the non-vitrified silica layers deposited in step i); iii) removal of the hollow substrate tube from the vitrified silica layers deposited in step ii) and the non-vitrified silica layers deposited in step i) to obtain a deposited tube; iv) optional collapsing said deposited tube obtained in step iii) to obtain a deposited rod comprising from the periphery to the center at least one inner optical cladding and an optical core; v) preparation of an intermediate layer by the steps of: * deposition of non-vitrified silica layers on the outside surface of the deposited tube obtained in step iii) or deposited rod obtained in step iv) with a flame hydrolysis process in an outer reaction zone

Abstract: The invention relates to an optical fiber preform (20) comprising a primary preform (21) and one or more purified silica-based overclad layers (22) surrounding said primary preform (21), the purified silica-based overclad layers (22) comprising lithium and aluminium, and having a ratio between lithium concentration [Li] and aluminium concentration [Al] satisfying the following inequality: 1×10?3?[Li]/[Al]?20×10?3.

Abstract: The present invention relates to a method for manufacturing a preform for optical fibers, which method comprises the sequential steps of: i) deposition of non-vitrified silica layers on the inner surface of a hollow substrate tube; ii) deposition of vitrified silica layers inside the hollow substrate tube on the inner surface of the non-vitrified silica layers deposited in step i); iii) removal of the hollow substrate tube from the vitrified silica layers deposited in step ii) and the non-vitrified silica layers deposited in step i) to obtain a deposited tube; iv) optional collapsing said deposited tube obtained in step iii) to obtain a deposited rod comprising from the periphery to the center at least one inner optical cladding and an optical core; v) preparation of an intermediate layer by the steps of: *deposition of non-vitrified silica layers on the outside surface of the deposited tube obtained in step iii) or deposited rod obtained in step iv) with a flame hydrolysis process in an outer reaction zone u

Abstract: The invention relates to an optical fiber preform (20) comprising a primary preform (21) and one or more purified silica-based overclad layers (22) surrounding said primary preform (21), the purified silica-based overclad layers (22) comprising lithium and aluminium, and having a ratio between lithium concentration [Li] and aluminium concentration [Al] satisfying the following inequality (Formula (I)). 1.103?[Li]/[Al]?20.

Abstract: Disclosed is an amplifying optical fiber that includes a central core that is suitable for transmitting and amplifying an optical signal and a surrounding optical cladding that is suitable for confining the optical signal transmitted in the central core. The central core is formed from a main matrix that contains nanoparticles doped with at least one rare earth element. The weight concentration of the rare earth dopants in the nanoparticles is typically between about 1 and 20 percent, and the nanoparticle concentration in the central core's main matrix is between about 0.05 percent and 1 percent by volume. The disclosed optical fiber incorporates rare earth ions at high concentrations yet avoids the phenomenon of photodarkening at high transmission power.

Abstract: The present invention embraces an amplifying optical fiber having a central core adapted to convey and amplify an optical signal and a cladding that surrounds the central core to confine the optical signal conveyed in the central core. The central core is formed of a core matrix in which nanoparticles are present. The nanoparticles themselves include a nanoparticle matrix and rare-earth-dopant elements. The core matrix may also include one or more additional dopants (i.e., in addition to nanoparticles). The amplifying optical fiber possesses a small numerical aperture and is suitable for use in high-pump-power applications without a degraded gain shape.

Abstract: Disclosed is a stimulated Raman scattering effect (SRS), amplifying optical fiber that includes a central core comprising a dielectric matrix that is capable of vibrating at a given frequency (?Raman) under the effect of a pump signal. The optical fiber includes at least one kind of metallic nanostructure that is capable of generating surface plasmon resonance (SPR) in the optical fiber. The metallic nanostructures have a shape and composition such that the frequency of their surface plasmon resonance (?plasmon) corresponds to the frequency of the pump signal (?pump) and/or the frequency of the optical signal transmitted in the optical fiber (?signal).

Abstract: An optical fiber preform comprises a primary preform that includes at least one inner cladding and a central core deposited inside a fluorine doped silica tube. The fluorine doped silica tube has a cross section area that is no more than about 15 percent smaller than the cross section area of the primary preform. The optical fiber preform has a large capacity, may be manufactured at reduced cost, and may be drawn to produce an optical fiber having reduced transmission losses.

Abstract: A method for manufacturing an optical fiber preform includes the steps of depositing an inner cladding and a central core inside a fluorine doped silica tube and thereafter collapsing the silica tube to form a primary preform. The fluorine doped silica tube has a cross section area that is no more than about 15 percent smaller than the cross section area of the resulting primary preform. The present method facilitates reduced-cost manufacturing of a high-capacity optical fiber preform, which may be drawn to produce an optical fiber having reduced transmission losses.

Abstract: Disclosed is a method of heat treating quartz glass deposition tubes at between 900° C. and 1200° C. for at least 115 hours. The resulting deposition tubes are useful in forming optical preforms that can yield optical fibers having reduced added loss.

Abstract: An optical fiber includes a central core and an optical cladding. The central core includes a core matrix surrounding nanoparticles. The nanoparticles include rare earths, a nanoparticle matrix, and an outer layer. The nanoparticle matrix surrounds the rare earths, and the outer layer surrounds the nanoparticle matrix. The atomic ratio of nanoparticle matrix atoms other than oxygen to rare earth atoms is typically between about 300 and 1,000. The outer layer, which typically has a thickness of between about 1 nanometer and 2 nanometers, includes an outer layer matrix that is substantially free from rare earths.

Abstract: The invention relates to a method for manufacturing a final optical fiber preform by overcladding, said method comprising the steps of providing a primary preform; positioning said primary preform within at least one tube, wherein the at least one tube partly covers the primary preform to create a zone to be overcladded, being an overclad zone, which overclad zone is located on the primary preform outside the at least one tube; injecting a gas into the annular space between the primary preform and the at least one tube under overpressure relative to the pressure outside the at least one tube; overcladding the primary preform in the overclad zone with an overcladding material using an overcladding device. The invention also relates to an apparatus for carrying out the method. The invention allows overcladding a primary preform at low cost while maximally limiting the incorporation of impurities into the silica overclad.

Abstract: Disclosed is a method of heat treating quartz glass deposition tubes at between 900° C. and 1200° C. for at least 115 hours. The resulting deposition tubes are useful in forming optical preforms that can yield optical fibers having reduced added loss.

Abstract: Disclosed is a method of heat treating quartz glass deposition tubes at between 900° C. and 1200° C. for at least 115 hours. The resulting deposition tubes are useful in forming optical preforms that can yield optical fibers having reduced added loss.

Abstract: The present invention embraces an amplifying optical fiber having a central core adapted to convey and amplify an optical signal and a cladding that surrounds the central core to confine the optical signal conveyed in the central core. The central core is formed of a core matrix in which nanoparticles are present. The nanoparticles themselves include a nanoparticle matrix and rare-earth-dopant elements. The core matrix may also include one or more additional dopants (i.e., in addition to nanoparticles). The amplifying optical fiber possesses a small numerical aperture and is suitable for use in high-pump-power applications without a degraded gain shape.

Abstract: Disclosed is a plasma torch for overcladding a primary preform of an optical fiber. The plasma torch includes a confinement tube for confining an induced plasma and a torch base. The torch base has a ceramic surface internal to the confinement tube. The plasma torch has extended life even at high input powers.

Abstract: Disclosed is a stimulated Raman scattering effect (SRS), amplifying optical fiber that includes a central core comprising a dielectric matrix that is capable of vibrating at a given frequency (?Raman) under the effect of a pump signal. The optical fiber includes at least one kind of metallic nanostructure that is capable of generating surface plasmon resonance (SPR) in the optical fiber. The metallic nanostructures have a shape and composition such that the frequency of their surface plasmon resonance (?plasmon) corresponds to the frequency of the pump signal (?pump) and/or the frequency of the optical signal transmitted in the optical fiber (?signal).

Abstract: A method for manufacturing an optical fiber preform includes the steps of depositing an inner cladding and a central core inside a fluorine doped silica tube and thereafter collapsing the silica tube to form a primary preform. The fluorine doped silica tube has a cross section area that is no more than about 15 percent smaller than the cross section area of the resulting primary preform. The present method facilitates reduced-cost manufacturing of a high-capacity optical fiber preform, which may be drawn to produce an optical fiber having reduced transmission losses.

Abstract: An optical fiber preform comprises a primary preform that includes at least one inner cladding and a central core deposited inside a fluorine doped silica tube. The fluorine doped silica tube has a cross section area that is no more than about 15 percent smaller than the cross section area of the primary preform. The optical fiber preform has a large capacity, may be manufactured at reduced cost, and may be drawn to produce an optical fiber having reduced transmission losses.

Abstract: Disclosed is an amplifying optical fiber that includes a central core that is suitable for transmitting and amplifying an optical signal and a surrounding optical cladding that is suitable for confining the optical signal transmitted in the central core. The central core is formed from a main matrix that contains nanoparticles doped with at least one rare earth element. The weight concentration of the rare earth dopants in the nanoparticles is typically between about 1 and 20 percent, and the nanoparticle concentration in the central core's main matrix is between about 0.05 percent and 1 percent by volume. The disclosed optical fiber incorporates rare earth ions at high concentrations yet avoids the phenomenon of photodarkening at high transmission power.