Abstract: A fiber optic article can comprise a core, an inner region disposed about the core and a cladding disposed about the inner region. The index of refraction of the cladding can be less than that of the inner region, and the index of refraction of the inner region can be less than that of the core. The fiber can include a second cladding disposed about the cladding, where the second cladding has an index of refraction that is less than the index of refraction of the cladding. The inner region can have a non circular outer perimeter that includes at least one inwardly oriented section. The article can be elongate along a longitudinal axis and can include at least one longitudinally extending region, such as a stress inducing region, for providing birefringence and the inwardly oriented region can face the longitudinally extending region. The fiber optic article can include active material for providing light responsive to the article receiving pump light, such as, for example, one or more rare earths.

Abstract: An optical fiber comprises a photosensitive core that includes a concentration of a first material that increases the refractive index of the core and a concentration of a second material that is other than boron and that reduces the refractive index of the core. A cladding is disposed about the core for tending to confine light to the core. The fiber also includes at least one longitudinally extending region having a thermal coefficient of expansion that is different from the thermal coefficient of expansion of the cladding. In another embodiment, the core includes a concentration of germanium and a concentration of boron. Also disclosed is a polarization-maintaining double-clad (PM DC) fiber comprising one or both of at least one circular axially extending stress inducing region(s) and an inner cladding comprising a circular outer perimeter.

Abstract: An optical fiber comprises a photosensitive core that includes a concentration of a first material that increases the refractive index of the core and a concentration of a second material that is other than boron and that reduces the refractive index of the core. A cladding is disposed about the core for tending to confine light to the core. The fiber also includes at least one longitudinally extending region having a thermal coefficient of expansion that is different from the thermal coefficient of expansion of the cladding. In another embodiment, the core includes a concentration of germanium and a concentration of boron. Also disclosed is a polarization-maintaining double-clad (PM DC) fiber comprising one or both of at least one circular axially extending stress inducing region(s) and an inner cladding comprising a circular outer perimeter.

Abstract: A fiber optic article, such as an optical fiber or an optical preform, can include a core comprising a concentration of erbium, a concentration of fluorine and a concentration of ytterbium for sensitizing the erbium by absorbing pump light and transferring energy to the erbium. The erbium can provide light having a second wavelength different than the wavelength of the pump light. The article can also include a concentration of phosphorus. The fiber optic article can include a cladding disposed about the core, where the cladding has an index of refraction that is less than the index of refraction of the core, and a second cladding disposed about the first cladding, where the second cladding includes an index of refraction than is less than the index of refraction of the cladding. The fiber optic article can be elongate along a longitudinal axis and can include a longitudinally extending region for providing birefringence.

Abstract: An optical fiber comprises a photosensitive core that includes a concentration of a first material that increases the refractive index of the core and a concentration of a second material that is other than boron and that reduces the refractive index of the core. A cladding is disposed about the core for tending to confine light to the core. The fiber also includes at least one longitudinally extending region having a thermal coefficient of expansion that is different from the thermal coefficient of expansion of the cladding. In another embodiment, the core includes a concentration of germanium and a concentration of boron. Also disclosed is a polarization-maintaining double-clad (PM DC) fiber comprising one or both of at least one circular axially extending stress inducing region(s) and an inner cladding comprising a circular outer perimeter.

Abstract: A polarization maintaining optical fiber has a core extending along a longitudinal axis, where the core includes a rare earth and a first index of refraction. A cladding is disposed about the core and has a first thermal coefficient of expansion (TCE) and a second index of refraction that is less than the first index of refraction. The fiber can include a pair of longitudinally extending members, and each of the members can have a TCE that is different than the first TCE of the cladding. The pair can be spaced apart by a distance di. A second cladding can be disposed about the first cladding, and the second cladding can have a third index of refraction that is less than the second index of refraction. The fiber can have a fundamental mode having a mode field diameter (MFD). The core can be a multimode core having a diameter dc that is greater than or equal to 15 microns, the numerical aperture of the core relative to the first cladding can be less than or equal to 0.

Abstract: A fiber optic article can comprise a core, an inner region disposed about the core and a cladding disposed about the inner region. The index of refraction of the cladding can be less than that of the inner region, and the index of refraction of the inner region can be less than that of the core. The fiber can include a second cladding disposed about the cladding, where the second cladding has an index of refraction that is less than the index of refraction of the cladding. The inner region can have a non circular outer perimeter that includes at least one inwardly oriented section. The article can be elongate along a longitudinal axis and can include at least one longitudinally extending region, such as a stress inducing region, for providing birefringence and the inwardly oriented region can face the longitudinally extending region. The fiber optic article can include active material for providing light responsive to the article receiving pump light, such as, for example, one or more rare earths.

Abstract: A fiber optic article, such as an optical fiber or an optical preform, can include a core comprising a concentration of erbium, a concentration of fluorine and a concentration of ytterbium for sensitizing the erbium by absorbing pump light and transferring energy to the erbium. The erbium can provide light having a second wavelength different than the wavelength of the pump light. The article can also include a concentration of phosphorus. The fiber optic article can include a cladding disposed about the core, where the cladding has an index of refraction that is less than the index of refraction of the core, and a second cladding disposed about the first cladding, where the second cladding includes an index of refraction than is less than the index of refraction of the cladding. The fiber optic article can be elongate along a longitudinal axis and can include a longitudinally extending region for providing birefringence.

Abstract: A fiber optic article can comprise a core, an inner region disposed about the core and a cladding disposed about the inner region. The index of refraction of the cladding can be less than that of the inner region, and the index of refraction of the inner region can be less than that of the core. The fiber can include a second cladding disposed about the cladding, where the second cladding has an index of refraction that is less than the index of refraction of the cladding. The inner region can have a non circular outer perimeter that includes at least one inwardly oriented section. The article can be elongate along a longitudinal axis and can include at least one longitudinally extending region, such as a stress inducing region, for providing birefringence and the inwardly oriented region can face the longitudinally extending region. The fiber optic article can include active material for providing light responsive to the article receiving pump light, such as, for example, one or more rare earths.

Abstract: A fiber optic article, such as an optical fiber or an optical preform, can include a core comprising a concentration of erbium, a concentration of fluorine and a concentration of ytterbium for sensitizing the erbium by absorbing pump light and transferring energy to the erbium. The erbium can provide light having a second wavelength different than the wavelength of the pump light. The article can also include a concentration of phosphorus. The fiber optic article can include a cladding disposed about the core, where the cladding has an index of refraction that is less than the index of refraction of the core, and a second cladding disposed about the first cladding, where the second cladding includes an index of refraction than is less than the index of refraction of the cladding. The fiber optic article can be elongate along a longitudinal axis and can include a longitudinally extending region for providing birefringence.

Abstract: A fiber optic article can comprise a core, an inner region disposed about the core and a cladding disposed about the inner region. The index of refraction of the cladding can be less than that of the inner region, and the index of refraction of the inner region can be less than that of the core. The fiber can include a second cladding disposed about the cladding, where the second cladding has an index of refraction that is less than the index of refraction of the cladding. The inner region can have a non circular outer perimeter that includes at least one inwardly oriented section. The article can be elongate along a longitudinal axis and can include at least one longitudinally extending region, such as a stress inducing region, for providing birefringence and the inwardly oriented region can face the longitudinally extending region. The fiber optic article can include active material for providing light responsive to the article receiving pump light, such as, for example, one or more rare earths.

Abstract: An optical fiber for use in making components of an optical communication system has cladding and core materials the constituents of which cause a component made from the fiber to have a rate of change with respect to temperature of a response to a signal which passes through zero at a temperature Tm, where the temperature Tm is at or near a selected temperature, or falls within a selected temperature range; and the value of Tm of a fiber can be controllably changed by changing the concentration of a selected constituent of the fiber, such as, for example, the concentration of boron.

Abstract: A polarization maintaining optical fiber has a core extending along a longitudinal axis, where the core includes a rare earth and a first index of refraction. A cladding is disposed about the core and has a first thermal coefficient of expansion (TCE) and a second index of refraction that is less than the first index of refraction. The fiber can include a pair of longitudinally extending members, and each of the members can have a TCE that is different than the first TCE of the cladding. The pair can be spaced apart by a distance di. A second cladding can be disposed about the first cladding, and the second cladding can have a third index of refraction that is less than the second index of refraction. The fiber can have a fundamental mode having a mode field diameter (MFD). The core can be a multimode core having a diameter dc that is greater than or equal to 15 microns, the numerical aperture of the core relative to the first cladding can be less than or equal to 0.

Abstract: An optical fiber for use in making components of an optical communication system has cladding and core materials the constituents of which cause a component made from the fiber to have a rate of change with respect to temperature of a response to a signal which passes through zero at a temperature Tm which is at or near a selected temperature, or falls within a selected temperature range; and the value of Tm of a fiber can be controllably changed by changing the concentration of B2O3 in the fiber core material.

Abstract: A polarization maintaining optical fiber has a core extending along a longitudinal axis, where the core includes a rare earth and a first index of refraction. A cladding is disposed about the core and has a first thermal coefficient of expansion (TCE) and a second index of refraction that is less than the first index of refraction. The fiber can include a pair of longitudinally extending members, and each of the members can have a TCE that is different than the first TCE of the cladding. The pair can be spaced apart by a distance di. A second cladding can be disposed about the first cladding, and the second cladding can have a third index of refraction that is less than the second index of refraction. The fiber can have a fundamental mode having a mode field diameter (MFD). The core can be a multimode core having a diameter dc that is greater than or equal to 15 microns, the numerical aperture of the core relative to the first cladding can be less than or equal to 0.

Abstract: An optical fiber comprises a photosensitive core that includes a concentration of a first material that increases the refractive index of the core and a concentration of a second material that is other than boron and that reduces the refractive index of the core. A cladding is disposed about the core for tending to confine light to the core. The fiber also includes at least one longitudinally extending region having a thermal coefficient of expansion that is different from the thermal coefficient of expansion of the cladding. In another embodiment, the core includes a concentration of germanium and a concentration of boron. Also disclosed is a polarization-maintaining double-clad (PM DC) fiber comprising one or both of at least one circular axially extending stress inducing region(s) and an inner cladding comprising a circular outer perimeter.

Abstract: An optical fiber for use in making components of an optical communication system has cladding and core materials the constituents of which cause a component made from the fiber to have a rate of change with respect to temperature of a response to a signal which passes through zero at a temperature Tm, where the temperature Tm is at or near a selected temperature, or falls within a selected temperature range; and the value of Tm of a fiber can be controllably changed by changing the concentration of a selected constituent of the fiber, such as, for example, the concentration of boron.

Abstract: An optical fiber for use in making components of an optical communication system has cladding and core materials the constituents of which cause a component made from the fiber to have a rate of change with respect to temperature of a response to a signal which passes through zero at a temperature Tm which is at or near a selected temperature, or falls within a selected temperature range; and the value of Tm of a fiber can be controllably changed by changing the concentration of B2O3 in the fiber core material.