A method of processing by controlling one or more beam characteristics of an optical beam may include: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP and one or more confinement regions; modifying the one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; confining the modified one or more beam characteristics of the optical beam within the one or more confinement regions of the second length of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP may differ from the second RIP.

The field of integrated health monitoring using Bragg grating optical fibre sensors including a sensor and methods for locating and installing this sensor on a support. The Bragg grating optical fibre sensor includes an optical fibre wherein at least one set of patterns forming a Bragg grating is written, the optical fibre further including a set of microstructures in the vicinity of each Bragg grating, the microstructures being separate from the patterns forming the Bragg grating, each microstructure being capable of scattering a portion of a light beam within a predetermined range of scattering wavelengths.

An optical fiber amplifier according to one embodiment includes a multicore fiber doped with erbium, and the multicore fiber is twisted and helically wound to form a fiber coil.

One embodiment of the present disclosure relates to an SFG (slanted fiber grating) that can easily realize a high-performance gain equalizer. The SFG includes an optical fiber comprised of silica-based glass and including a core, a first cladding containing a photosensitive material, and a second cladding. A specific section between two different points arranged along a fiber axis in the optical fiber is configured with a first region, a pair of second regions, and a third region. The first region includes a slanted Bragg grating provided in a region as the first cladding. The pair of second regions are arranged to sandwich the first region. The third region is disposed to sandwich both the first region and the pair of second regions. An MFD at a wavelength of 1.55 μm in the third region is smaller than an MFD at a wavelength of 1.55 μm in the first region.

An optical fiber may include a first core, a second core, and a cladding surrounding the first core and the second core. The second core may be at an off-center location with respect to a center of the optical fiber, or the second core may include an azimuthally nonuniform section at the off-center location. The second core may twist about an axis of the optical fiber along a length of the optical fiber, and the second core being twisted about the axis may cause an optical beam, launched into the second core at a first end of the optical fiber, to be at least partially converted to a rotary optical beam at a second end of the optical fiber.

A manufacturing method for an optical fiber, includes: drawing, while heating in a heating furnace, a lower end of an optical fiber preform that is to be an optical fiber having a core consisting of silica glass containing a rare earth element compound. The heating furnace has a temperature profile in which a temperature of the heating furnace increases to a maximum temperature T.sub.max and then decreases from an upstream side of the heating furnace toward a downstream side of the heating furnace. The temperature profile has a changing point at which the temperature decreases more steeply on the downstream side from a position where the maximum temperature T.sub.max is reached. At the maximum temperature, a temperature of the silica glass is higher than or equal to a glass transition temperature and the silica glass is in a single phase.

An apparatus for sensing a value of a property in a borehole having hydrogen gas penetrating a subsurface formation includes an optical fiber configured to be disposed in the borehole having the hydrogen gas and comprising a core having a fiber Bragg grating that is responsive to the value of the property and a cladding disposed about the core, wherein (i) the core is doped with a first dopant that is photo-sensitive for writing the fiber Bragg grating and that has a concentration in the core of 2 Mole % or less and (ii) the cladding is doped with a second dopant that lowers an index of refraction of the cladding.

A method for determining a curvature and/or torsion of an optical waveguide of a fibre-optic sensor, comprising at least two Bragg gratings introduced into the optical waveguide and extending through a common cross-sectional plane, situated in a radial direction, through the optical waveguide, wherein the Bragg gratings are introduced in the core and/or on the boundary between the core and the cladding and/or in an inner edge region of the cladding within an evanescence region of the light, the method comprising: providing reference data of intensities of reflected light portions of light coupled into the optical waveguide, in particular depending on known reference deformations of the optical waveguide, measuring at least one light intensity of reflected light portions of light coupled into the optical waveguide, wherein the optical waveguide has a deformation to be determined, and determining the deformation by comparing the light intensity with the reference data.

An optical dispersion compensator integrated with a silicon photonics system including a first phase-shifter coupled to a second phase-shifter in parallel on the silicon substrate characterized in an athermal condition. The dispersion compensator further includes a third phase-shifter on the silicon substrate to the first phase-shifter and the second phase-shifter through two 2×2 splitters to form an optical loop. A second entry port of a first 2×2 splitter is for coupling with an input fiber and a second exit port of a second 2×2 splitter is for coupling with an output fiber. The optical loop is characterized by a total phase delay tunable via each of the first phase-shifter, the second phase-shifter, and the third phase-shifter such that a normal dispersion (>0) at a certain wavelength in the input fiber is substantially compensated and independent of temperature.

Systems, apparatuses, and methods are described for modifying a beam parameter product of a laser beam. The modified beam parameter product may increase the number of tasks that may be performed using a given laser with its original beam parameter product. By increasing the beam parameter product of a laser, an initial low beam parameter product beam may be used to perform tasks requiring a higher beam parameter product. The beam may be modified to redirect portions of the beam at different angles via one or more non-imaging refracting optical components or by one or more Fiber Bragg gratings.