Abstract: A method of measuring temperature includes positioning an optical fiber in contact with an object or in an environment having a temperature to be determined, where the optical fiber comprises a core surrounded by a cladding; the core comprises an alkaline-earth fluorosilicate glass including defects, and the cladding comprises a silica glass. Infrared light is supplied to the optical fiber, thereby electronically exciting the defects. Green light emitted from the defects is detected, and an intensity value of the green light is obtained and converted to a temperature value for the optical fiber, whereby the temperature of the object or environment is determined. The green light may be detected along a length of the optical fiber, and a plurality of intensity values may be converted to a plurality of temperature values along the fiber length, thereby obtaining a distributed measurement of the temperature of the object or environment.

Abstract: A microheater comprises an optical fiber including a rare earth-doped glass core surrounded by a glass cladding. The rare earth-doped glass core comprises a rare earth dopant at a concentration sufficient for luminescence quenching such that, when the rare earth dopant is pumped with light at an absorption band wavelength, at least about 90% of absorbed pump light is converted into heat.

Abstract: A rare earth-doped optical fiber comprises a fluorosilicate core surrounded by a silica cladding, where the fluorosilicate core comprises an alkaline-earth fluoro-alumino-silicate glass, such as a strontium fluoro-alumino-silicate glass. The rare earth-doped optical fiber may be useful as a high-power fiber laser and/or fiber amplifier. A method of making a rare earth-doped optical fiber comprises: inserting a powder mixture comprising YbF3, SrF2, and Al2O3 into a silica tube; after inserting the powder mixture, heating the silica tube to a temperature of at least about 2000° C., some or all of the powder mixture undergoing melting; drawing the silica tube to obtain a reduced-diameter fiber; and cooling the reduced-diameter fiber. Thus, a rare earth-doped optical fiber comprising a fluorosilicate core surrounded by a silica cladding is formed.

Abstract: A microheater comprises an optical fiber including a rare earth-doped glass core surrounded by a glass cladding. The rare earth-doped glass core comprises a rare earth dopant at a concentration sufficient for luminescence quenching such that, when the rare earth dopant is pumped with light at an absorption band wavelength, at least about 90% of absorbed pump light is converted into heat.

Abstract: A rare earth-doped optical fiber comprises a fluorosilicate core surrounded by a silica cladding, where the fluorosilicate core comprises an alkaline-earth fluoro-alumino-silicate glass, such as a strontium fluoro-alumino-silicate glass. The rare earth-doped optical fiber may be useful as a high-power fiber laser and/or fiber amplifier. A method of making a rare earth-doped optical fiber comprises: inserting a powder mixture comprising YbF3, SrF2, and Al2O3 into a silica tube; after inserting the powder mixture, heating the silica tube to a temperature of at least about 2000° C., some or all of the powder mixture undergoing melting; drawing the silica tube to obtain a reduced-diameter fiber; and cooling the reduced-diameter fiber. Thus, a rare earth-doped optical fiber comprising a fluorosilicate core surrounded by a silica cladding is formed.

Abstract: Acoustically anti-guiding optical structures are provided. In an exemplary acoustically anti-guiding fiber, a suitable cladding size for ant guiding fibers occurs wherein the cladding size is determined such that the net material dampening in the cladding is large enough to dampen acoustic waves. In another embodiment, a cladding can be considered infinite if the round-trip time from a core to an outer cladding boundary (or interface) is greater than a coherence time of an acoustic wave.

Abstract: An optical fiber may be constructed of a material having at least first and second constituents. The constituents and their relative abundance are selected such that the aggregate Brillouin frequency-shift response exhibited by a fiber constructed using the combined material is insensitive to a selected physical condition, such as temperature or strain, or the sensitivity is below an acceptable application-specific level, over an acceptable range of conditions. The constituents are selected such that the slopes or derivatives of the Brillouin frequency-shift response (with respect to the selected physical condition) of two of the constituents have opposite signs, and are combined in proper quantities such that the constituents balance each other to reduce the slope or derivative of the aggregate Brillouin frequency-shift response of the combined material to zero, or to an acceptable application-specific level, over an acceptable range of conditions.

Abstract: A method for creating a composite material for fabricating an optical fiber. The method includes selecting multiple constituents and a concentration for each constituent, conceptually dividing a unit length model rod into a number of segments, computing origin locations for the segments, computing a longitudinal acoustic velocity for an assumed composite material, computing a photoelastic constant for the assumed composite material, computing an acoustic frequency for the assumed composite material, computing an acoustic attenuation coefficient for the assumed composite material, computing a Brillouin Spectral Width for the assumed composite material, and computing a Brillouin Gain Coefficient for the assumed composite material. if the computed Brillouin Gain Coefficient is greater than a preselected value, repeating the above, otherwise, mixing the constituents at an appropriate temperature. The number equals the number of constituents, and each segment is associated with a separate one of the constituents.

Abstract: Acoustically anti-guiding optical structures are provided. In an exemplary acoustically anti-guiding fiber, a suitable cladding size for ant guiding fibers occurs wherein the cladding size is determined such that the net material dampening in the cladding is large enough to dampen acoustic waves. In another embodiment, a cladding can be considered infinite if the round-trip time from a core to an outer cladding boundary (or interface) is greater than a coherence time of an acoustic wave.

Abstract: A narrow-linewidth micropulse LIDAR transmitter based on a low-SBS single clad, small-mode-area optical fiber. High narrow-linewidth peak powers are achieved through the use of an erbium doped fiber with an acoustic waveguide. Over 6 ?J per pulse (100 ns pulse width) is achieved before a weak form of stimulated Brillouin scattering appears. This laser has the potential to scale to very high power in a low-SBS dual clad fiber.

Abstract: A narrow linewidth injection-seeded Q-switched fiber ring laser based on a low-SBS optical fiber. High peak powers are achieved through the use of a single-clad erbium doped fiber with an acoustic waveguide. 12.5 ?J per pulse (250ns pulse width) is achieved before a weakened form of stimulated Brillouin scattering appears. This laser has the potential to scale to very high power in a low-SBS dual clad fiber.

Abstract: A narrow linewidth, injection seeded, Q-switched Er fiber ring oscillator, that provides over 600 ?W of average output power at 500 Hz, with 1.2 ?J per pulse, before the output appears to be significantly affected by stimulated Brillouin scattering. This laser configuration provides multiple advantages in LIDAR systems because it offers the possibility of broad and rapid tunability.

Abstract: A waveguide configuration comprising a core, a first cladding, a second cladding, and a buffer. The core includes an index of refraction and an acoustic shear velocity. The first cladding extends about the core and has an acoustic shear velocity which is less than that of the core and an index of refraction which is less than the core. The second cladding extends about the first cladding. The second cladding has an acoustic shear velocity which is greater than that of the first cladding and less than the acoustic shear velocity of the core. The second cladding has an index of refraction which is less than that of an optical mode. The buffer extends about the second cladding.

Abstract: A waveguide configuration comprising an optical core, an optical cladding, an acoustic core and an acoustic cladding. The acoustic core has two regions. The first region radial thickness is smaller than the optical core radial thickness and the sum of the first region radial thickness and the second region radial thickness is greater than the optical core radial thickness. The first region acoustic velocity is greater than the second region acoustic velocity and the acoustic cladding acoustic velocity is greater than the second region acoustic velocity. In one variation, the first region acoustic velocity is less than the second region acoustic velocity and the acoustic cladding acoustic velocity is less than the second region acoustic velocity.

Abstract: A waveguide configuration comprising a core, a first cladding, a second cladding, and a buffer. The core includes an index of refraction and an acoustic shear velocity. The first cladding extends about the core and has an acoustic shear velocity which is less than that of the core and an index of refraction which is less than the core. The second cladding extends about the first cladding. The second cladding has an acoustic shear velocity which is greater than that of the first cladding and less than the acoustic shear velocity of the core. The second cladding has an index of refraction which is less than that of an optical mode. The buffer extends about the second cladding.

Abstract: A waveguide configuration comprising a core, a first cladding, a second cladding, and a buffer. The core includes an index of refraction and an acoustic shear velocity. The first cladding extends about the core and has an acoustic shear velocity which is less than that of the core and an index of refraction which is less than the core. The second cladding extends about the first cladding. The second cladding has an acoustic shear velocity which is greater than that of the first cladding and less than the acoustic shear velocity of the core. The second cladding has an index of refraction which is less than that of an optical mode. The buffer extends about the second cladding.

Abstract: A narrow linewidth injection-seeded Q-switched fiber ring laser based on a low-SBS optical fiber. High peak powers are achieved through the use of a single-clad erbium doped fiber with an acoustic waveguide. 12.5 ?J per pulse (250 ns pulse width) is achieved before a weakened form of stimulated Brillouin scattering appears. This laser has the potential to scale to very high power in a low-SBS dual clad fiber.

Abstract: A narrow-linewidth micropulse LIDAR transmitter based on a low-SBS single clad, small-mode-area optical fiber. High narrow-linewidth peak powers are achieved through the use of an erbium doped fiber with an acoustic waveguide. Over 6 ?J per pulse (100 ns pulse width) is achieved before a weak form of stimulated Brillouin scattering appears. This laser has the potential to scale to very high power in a low-SBS dual clad fiber.

Abstract: A waveguide configuration comprising an optical core, an optical cladding, an acoustic core and an acoustic cladding. The acoustic core has two regions. The first region radial thickness is smaller than the optical core radial thickness and the sum of the first region radial thickness and the second region radial thickness is greater than the optical core radial thickness. The first region acoustic velocity is greater than the second region acoustic velocity and the acoustic cladding acoustic velocity is greater than the second region acoustic velocity. In one variation, the first region acoustic velocity is less than the second region acoustic velocity and the acoustic cladding acoustic velocity is less than the second region acoustic velocity.

Abstract: A waveguide configuration comprising a core, a first cladding, a second cladding, and a buffer. The core includes an index of refraction and an acoustic shear velocity. The first cladding extends about the core and has an acoustic shear velocity which is less than that of the core and an index of refraction which is less than the core. The second cladding extends about the first cladding. The second cladding has an acoustic shear velocity which is greater than that of the first cladding and less than the acoustic shear velocity of the core. The second cladding has an index of refraction which is less than that of an optical mode. The buffer extends about the second cladding.