Abstract: A double-clad optical fiber includes a core, an inner cladding and an outer cladding of silica-based glass. The core may have a radius of less than about 5 ?m, a first index of refraction n1 and does not contain any active rare-earth dopants. The inner cladding may surround the core and includes a radial thickness of at least about 25 ?m, a numerical aperture of at least about 0.25, and a second index of refraction n2 such that n2<n1. The relative refractive index percent (? %) of the core relative to the inner cladding may be greater than about 0.1%. The outer cladding may surround the inner cladding and include a radial thickness from about 10 pm to about 50 ?m and a third index of refraction n3 such that n3<n2. The relative refractive index percent (? %) of the inner cladding relative to the outer cladding may be greater than about 1.5%.

Abstract: A double-clad optical fiber includes a core, an inner cladding and an outer cladding of silica-based glass. The core may have a radius of less than about 5 ?m, a first index of refraction n1 and does not contain any active rare-earth dopants. The inner cladding may surround the core and includes a radial thickness of at least about 25 ?m, a numerical aperture of at least about 0.25, and a second index of refraction n2 such that n2<n1. The relative refractive index percent (?%) of the core relative to the inner cladding may be greater than about 0.1%. The outer cladding may surround the inner cladding and include a radial thickness from about 10 ?m to about 50 ?m and a third index of refraction n3 such that n3<n2. The relative refractive index percent (?%) of the inner cladding relative to the outer cladding may be greater than about 1.5%.

Abstract: According to one example of the invention an optical fiber comprises: (i) a silica based core, said core having a core diameter greater than 80 ?m and a numerical aperture NA?0.24; and (ii) a silica based cladding in contact with and surrounding the core and having a second index of refraction n2, such that n1>n2; wherein the cladding includes B and F. Preferably the numerical aperture NA is at least 0.3.

Abstract: A double-clad optical fiber includes a core, an inner cladding and an outer cladding of silica-based glass. The core may have a radius of less than about 5 ?m, a first index of refraction n1 and does not contain any active rare-earth dopants. The inner cladding may surround the core and includes a radial thickness of at least about 25 ?m, a numerical aperture of at least about 0.25, and a second index of refraction n2 such that n2<n1. The relative refractive index percent (?%) of the core relative to the inner cladding may be greater than about 0.1%. The outer cladding may surround the inner cladding and include a radial thickness from about 10 ?m to about 50 ?m and a third index of refraction n3 such that n3<n2. The relative refractive index percent (?%) of the inner cladding relative to the outer cladding may be greater than about 1.5%.

Abstract: According to one example of the invention an optical fiber comprises: (i) a core consisting of Al doped silica having a first index of refraction n1; (ii) at least one silica based cladding surrounding the core and having a second index of refraction n2, such that n1>n2; (iii) a hermetic carbon based coating surrounding said cladding, said hermetic coating being 300 nm-1000 nm thick; and (iv) a second coating surrounding said hermetic coating, said second coating being 5 ?m to 80 ?m thick.

Abstract: An optical fiber includes a core and a cladding, said cladding having a refractive index nc a first coating directly contacting the cladding of said fiber, said coating having a thickness of less than 10 microns, said coating having a refractive index delta %=100×(ni2?nc2)/2ni2 less than ?1 percent. In another aspect, an optical fiber includes a core and a cladding, said cladding having a refractive index nc, a first coating directly contacting the cladding of said fiber, said fiber comprising a glass diameter less than 100 microns, said coating having a thickness of at least 8 microns, said coating having a refractive index delta %=100×(ni2?nc2)/2ni2 less than ?1 percent.

Abstract: An optical fiber, comprising: (i) a core having a core center and a radius or a width a, (ii) a cladding surrounding the core, and (iii) at least one stress member situated proximate to the fiber core within the cladding, said stress member comprising silica co-doped with F and at least one dopant selected from the list consisting of: GeO2, P2O5, Y2O3, TiO2 and Al2O3, wherein distance b between the stress member and the core center satisfies the following equation: 1?b/a<2.

Abstract: An optical fiber includes a core and a cladding, said cladding having a refractive index nc a first coating directly contacting the cladding of said fiber, said coating having a thickness of less than 10 microns, said coating having a refractive index delta %=100×(ni2-nc2)/2ni2 less than ?1 percent. In another aspect, an optical fiber includes a core and a cladding, said cladding having a refractive index nc, a first coating directly contacting the cladding of said fiber, said fiber comprising a glass diameter less than 100 microns, said coating having a thickness of at least 8 microns, said coating having a refractive index delta %=100×(ni2-nc2)/2ni2 less than ?1 percent.

Abstract: A method for measuring fundamental mode cutoff wavelength of single polarization fiber comprising: (i) launching pulsed light of at least one wavelength ?i into one end of the single polarization fiber; (ii) measuring backscattered light intensity corresponding to said wavelength to obtain the backscattered light intensity as a function of fiber position, wherein the backscattered light propagates through the same end of the fiber; and (iii) determining at least one cutoff wavelength and the corresponding position within said fiber for the cutoff wavelength, based on a specified threshold light intensity level.

Abstract: An optical fiber comprising: (i) a silica based passive core having a first index of refraction n1; (ii) a silica based cladding surrounding the core and having a second index of refraction n2, such that n1>n2, said cladding having at least one stress rod and at least one air hole extending longitudinally through the length of said optical fiber; and (iii) wherein said optical fiber supports a single polarization mode or poses polarization maintaining properties within the operating wavelength range.

Abstract: An optical fiber including: (i) a silica based, rare earth doped core having a first index of refraction n1; and (ii) at least one silica based cladding surrounding the core and having a second index of refraction n2, such that n1>n2, said cladding having a plurality of stress rods and a plurality of air holes extending longitudinally through the length of said optical fiber; wherein said optical fiber supports a single polarization mode or poses-polarization maintaining properties within the operating wavelength range.

Abstract: An optical fiber comprising: (i) a silica based passive core having a first index of refraction n1; (ii) a silica based cladding surrounding the core and having a second index of refraction n2, such that n1>n2, said cladding having at least one stress rod and at least one air hole extending longitudinally through the length of said optical fiber; and (iii) wherein said optical fiber supports a single polarization mode or poses polarization maintaining properties within the operating wavelength range.

Abstract: An optical fiber including: (i) a silica based, rare earth doped core having a first index of refraction n1; (ii) a silica based inner cladding surrounding the core and having a second index of refraction n2, such that n1>n2, said inner cladding having a plurality of air holes extending longitudinally through the length of said optical fiber; (iii) a silica based outer cladding surrounding said inner cladding and having a third index of refraction n3, such that n2>n3, wherein said optical fiber supports a single polarization mode within the operating wavelength range.

Abstract: An optical fiber including: (i) a silica based, rare earth doped core having a first index of refraction n1; and (ii) at least one silica based cladding surrounding the core and having a second index of refraction n2, such that n1>n2, said cladding having a plurality of stress rods and a plurality of air holes extending longitudinally through the length of said optical fiber; wherein said optical fiber supports a single polarization mode or poses-polarization maintaining properties within the operating wavelength range.

Abstract: A method for measuring fundamental mode cutoff wavelength of single polarization fiber comprising: (i) launching pulsed light of at least one wavelength ?i into one end of the single polarization fiber; (ii) measuring backscattered light intensity corresponding to said wavelength to obtain the backscattered light intensity as a function of fiber position, wherein the backscattered light propagates through the same end of the fiber; and (iii) determining at least one cutoff wavelength and the corresponding position within said fiber for the cutoff wavelength, based on a specified threshold light intensity level.

Abstract: An optical fiber, comprising: (i) a rare earth doped silica based elongated core with a first refractive index (n1) with an aspect ratio of 1:5 to 1; (ii) a silica based moat abutting and at least substantially surrounding the core, the moat having a refractive index n2, wherein n2<n1; (iii) a silica based inner cladding surrounding the moat, the inner cladding having a third refractive index (n3), wherein n1>n3; and n3>n2; (iv) a silica based outer cladding surrounding said inner cladding, the outer cladding having a fourth refractive index (n4), such that n4<n3; the optical fiber exhibits single polarization at the operating wavelength band.

Abstract: An optical fiber, comprising: a central core having a maximum dimension (A) greater than a minimum dimension (B) and a substantially elliptical shape, the fiber having at least one air hole positioned each opposite side of the central core wherein the optical fiber exhibits (i) single polarization propagation within a single polarization band and (ii) polarization maintaining property, such that the fiber beat length normalized at 1550 nm is less than 10 mm; and the polarization maintaining band is situated within wavelengths which are (a) adjacent to and below the single polarization band; and (b) above the higher order mode cutoff wavelength.

Abstract: Disclosed is an optical fiber (20) having a centermost laterally-elongated core (30) having a short dimension (a), a long dimension (b) and a first refractive index (n1), a moat (40) surrounding the central laterally-elongated core, the moat (40) having a second refractive index (n2), an outer dimension (c) and an outer dimension (d), and a cladding (50) surrounding the moat (40), the cladding (50) having a third refractive index (n3), wherein n1>n3>n2, a ratio of b/a is between 1.5 and 5.0, and a ratio of d/a is between 2.0 and 7.0. The fiber exhibits polarization maintaining properties in a PMB situated below (i.e., at shorter wavelength than SPB), such that beat length normalized to 1550 nm wavelength is preferably less than 10 mm. The fiber (20) may be coupled to optical components in apparatus where single polarization or polarization maintaining properties are desired.

Abstract: An optical fiber comprising: (i) a silica based, rare earth doped core having a first index of refraction n1; (ii) a silica based inner cladding surrounding the core having a second index of refraction n2, such that n1>n2; (iii) a silica based outer cladding surrounding the inner cladding having a third index of refraction n3 such that n2>n3, wherein inner cladding diameter is at least 125 ?m.

Abstract: An optical fiber including: (i) a silica based, rare earth doped core having a first index of refraction n1; (ii) a silica based inner cladding surrounding the core and having a second index of refraction n2, such that n1>n2, said inner cladding having a plurality of air holes extending longitudinally through the length of said optical fiber; (iii) a silica based outer cladding surrounding said inner cladding and having a third index of refraction n3, such that n2>n3, wherein said optical fiber supports a single polarization mode within the operating wavelength range.