Abstract: A design of a semiconductor saturable absorber that offers a convenient and reliable way to control/decrease the recovery time of the absorption. The absorption recovery time is controlled during the epitaxial growth by using lattice-mismatched layer(s) to induce dislocations, and implicitly non-radiative recombination centers within the nonlinear absorbing region. These lattice reformation layer(s) are interposed between the distributed Bragg reflector and the nonlinear absorption region, containing quantum-wells, quantum-dots or bulk semiconductor material. The thickness and composition of the lattice reformation layer(s) is an instrumental to control the amount of non-radiative recombination centers used to trap the optically excited carriers generated in the absorption region.

Abstract: Optical fiber lasers and components for optical fiber laser. An optical fiber laser can comprise a fiber laser cavity having a wavelength of operation at which the cavity provides output light, the cavity including optical fiber that guides light having the wavelength of operation, the fiber having first and second lengths, the first length having a core having a V-number at the wavelength of operation and a numerical aperture, the second length having a core that is multimode at the wavelength of operation and that has a V-number that is greater than the V-number of the core of the first length optical fiber at the wavelength of operation and a numerical aperture that is less than the numerical aperture of the core of the first length of optical fiber. At least one of the lengths comprises an active material that can provide light having the wavelength of operation via stimulated emission responsive to the optical fiber receiving pump light.

Abstract: Optical fiber source for providing polarized optical pulses, comprising a Q-switched fiber laser for providing substantially unpolarized seed pulses of optical energy, where the Q-switched fiber laser can comprise a laser cavity having a Q-switch and an optical fiber comprising a gain medium, where the optical fiber need not be a polarizing or polarization maintaining optical fiber; a passive polarizing element arranged to receive and substantially polarize the substantially unpolarized seed pulses; and a polarization maintaining fiber amplifier arranged for receiving the polarized seed pulses. The polarization maintaining fiber amplifier can comprise a selected polarizing or polarization maintaining fiber having a core comprising a gain medium for amplifying the substantially polarized seed pulses, where the core can be normally multimode at a an operating wavelength of the optical fiber source. The fiber amplifier can provide substantially polarized output pulses.

Abstract: Optical apparatus (110, 500, 600, 800, 1000) for providing light having a selected linear polarization having a polarization ratio, the apparatus (110, 500, 600, 800, 1000) comprising a length of optical fiber (120, 504, 604, 804, 1001) comprising a rare earth for providing light having a first wavelength responsive to receiving pump light having a second wavelength that is different than said first wavelength, wherein if the length of optical fiber (120, 504, 604, 804, 1004) were placed in a first position between the length of fiber (120, 504, 604, 804, 1004) is substantially linearly oriented (20) the fiber (120, 504, 604, 804, 1004) could propagate at the first wavelength a fundamental mode and a plurality of higher order modes and the apparatus (110, 500, 600, 800, 1000) could provide light having a first polarization ratio for the selected linear polarization and an M2 parameter, and wherein the length of fiber (120, 504, 604, 804, 1004) is positioned in a second position that increases the bend loss of

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 comprising a multimode glass core having a diameter of at least 250 microns and an index of refraction and a polymer cladding having a thickness and contactingly surrounding a glass portion of the fiber so as to define an interface between the glass portion and the polymer cladding. The polymer cladding can have a first index of refraction that is less than the index of refraction. The fiber can comprise a density of less than 0.25 non-conforming regions having a diameter of 25 microns or greater per millimeter of length along the fiber, where each of the non-conforming regions is a region visible to the human eye under an optical microscope and having at least a portion thereof within a selected distance of the interface. The selected distance can be less than or equal to the thickness of the polymer cladding. The optical microscope can have a total magnification of about 200. The polymer cladding can be applied to at least a part of the optical fiber in at least a class 1000 environment.

Abstract: A fiber amplifier for amplifying an optical signal, comprising a pump energy source capable of emitting energy at a pump wavelength: optical apparatus for transmitting the optical signal, the optical apparatus having a plurality of discrete portions, each discrete portion comprising a length of optical fiber and first and second components disposed at first and second respective locations and configured to substantially prevent energy having an intermediate wavelength in the discrete portion from entering other discrete portions of the optical apparatus; and a plurality of waveguides, each waveguide coupled to the pump energy source and to one of the plurality of discrete portions, each waveguide for providing energy at the pump wavelength from the pump energy source to its corresponding discrete portion, thereby increasing an intensity of light at the discrete portion's intermediate wavelength.

Abstract: A method of making an optical fiber article can include providing an optical fiber including at least a core; providing a preform; and subsequent to the foregoing providing of the optical fiber and the preform, drawing the preform so as to dispose a region about the optical fiber. An optical fiber article can include a core; a pump cladding disposed about the core, the pump cladding for propagating pump light; and a second cladding disposed about the pump cladding, where the second cladding can provide a photonic bandgap for tending to confine pump light to a region about which the second cladding is disposed. The second cladding can comprise a plurality of layers including a first layer having a different optical property than a second layer, and the plurality of layers can be arranged as to provide the photonic bandgap effect.

Abstract: An optical waveguide can include a first region (12), a core (14) and a cladding (16). The core (14) surrounds the first region (12), and the cladding (16) surrounds the core (14). Typically, the core (14) includes an active material. In a further aspect, the invention features a system that includes two fibers (10, 48). One of the fibers has a first region, a first core (e.g., a multimode core) surrounding the first region, and a cladding surrounding the core. The other fiber has a core (e.g., a single mode core). The fibers can optically communicate so that energy can propagate from one of the cores to the other of the cores of the two fibers. Typically, at least one of the cores includes an active material.

Abstract: An optical fiber coupler can include at least a first input optical fiber and an output optical fiber, where the first input optical fiber can comprise an antiguiding core, a first cladding disposed about the antiguiding core and a second cladding disposed about the first cladding so as to tend to confine light to said first cladding. The output fiber can comprise a guiding core, a first cladding disposed about the guiding core and a second cladding disposed about the first cladding of the output fiber for tending to confine light to the first cladding of the output fiber. Optical fibers are also disclosed, as are methods.

Abstract: Disclosed is an optical apparatus (10, 110, 410, 610) for accommodating optical fiber, such as one or more loops of optical fiber. The optical apparatus (10, 110, 410, 610) can include a body (12, 112, 412, 612) comprising an inwardly facing surface (16, 116, 416, 616) adapted for receiving a plurality of loops of a length of optical fiber. The body (16, 116, 416, 616) can include at least a portion (75) wherein the inwardly facing surface is continuous between two adjacent loops (79). Methods and apparatus are disclosed for disposing the optical fiber with an optical apparatus (10, 110, 410, 610) for accommodating the optical fiber.

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: Disclosed is an optical apparatus including an optical fiber having a wavelength of operation, the optical fiber comprising a first length of the optical fiber joined to a second length of the optical fiber with a splice such that the first and second lengths are in optical communication; a photodetector for sensing light leaking from the splice; and wherein the splice has a splice loss of not greater than 0.5 dB at the wavelength of operation. Methods of sensing light are also disclosed.

Abstract: In one aspect, the invention relates to optical fibers and systems that include such fibers. In another aspect, the invention provides an optical fiber that includes a core, a cladding surrounding the core, a layer surrounding the cladding, and a region between the layer and the cladding. The region can comprise an index of refraction that is different than an index of refraction comprised by the cladding. In one embodiment, the region can include a void containing air or a liquid. The void can be evacuated. The region can include a solid, such as, for example, a polymer. The layer can contact the cladding. The fiber can comprise rare earth ions.

Abstract: The invention features a fiber that includes an optical fiber (110) containing a gain medium having a Raman active material with a Raman gain spectrum. The optical fiber is configured to receive energy at a wavelength ?p. The fiber also includes at least three pairs of reflectors (120, 125, 150, 130, 160) disposed in the optical fiber. Each pair of reflectors forms a resonance cavity (140) with a resonance frequency.

Abstract: An optical fiber can include a glass core that is multimode at a selected wavelength and that comprises an index of refraction and a diameter Dcore, a glass cladding disposed about said glass core, said glass cladding comprising an outer diameter Dcladding and a first index of refraction that is less than said index of refraction of said core, and a second cladding disposed about said glass cladding, said second cladding comprising an optically cured polymer, said polymer comprising an index of refraction that is less than said first index of refraction. In certain embodiments, the fiber can include various other features. For example, [Dcladding/Dcore]2 can be no greater than 1.

Abstract: Optical fibers (e.g., fiber amplifiers and fiber lasers), and systems containing optical fibers (e.g., fiber amplifier systems and fiber laser systems) are disclosed.

Abstract: An optical waveguide can include a first region (12), a core (14) and a cladding (16). The core (14) surrounds the first region (12), and the cladding (16) surrounds the core (14). Typically, the core (14) includes an active material. In a further aspect, the invention features a system that includes two fibers (10, 48). One of the fibers has a first region, a first core (e.g., a multimode core) surrounding the first region, and a cladding surrounding the core. The other fiber has a core (e.g., a single mode core). The fibers can optically communicate so that energy can propagate from one of the cores to the other of the cores of the two fibers. Typically, at least one of the cores includes an active material.

Abstract: An optical fiber for the transmission of electromagnetic energy, where the fiber can have increased input power threshold for the onset of Stimulated Brillouin Scattering (SBS). The fiber can comprise a core and a cladding disposed about the core. The core can have a distribution of velocities for an acoustic wave associated with SBS, where the distribution of propagation velocities of the core for the acoustic wave is at least one of a) azimuthally asymmetric or b) non-constant in an azimuthal plane and longitudinally asymmetric. The fiber can be longitudinally asymmetric wherein the core includes a first portion having a propagation velocity for the acoustic wave that is substantially the same throughout interposed between longitudinally spaced portions each having a propagation velocity different than that of said first portion. Methods, such as, for example, methods for fabricating and/or using a fiber having an increased threshold input power for the onset of SBS, are also disclosed.

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.