Fujikura Limited

Panasonic Corporation

Kensuke Shima

Tetsuya Sakai

Ryozo Yamauchi

Akira Wada

Michihiro Nakai

Satoshi Okude

Kenji Nishide

Masahiro Kashiwagi

Hiroshi Hidaka

Shigefumi Yamasaki

Nobuyuki Tanaka

Masaaki Sudoh

Kazuhisa Yamamoto

Hiroyuki Furuya

Kuniharu Himeno

Shinichi Kadowaki

Shinichi Sakamoto

Tomoharu Kitabayashi

Yoshikiyo Noguchi

Yuu Ishii

Yasuhiro Mashiko

Takuya Ienaka

Yasuo Nakanishi

A fiber laser device includes a pumping light source, an amplifying fiber, an input side fiber fusion-spliced on an input side of the amplifying fiber and formed with a HR-FBG, an output side fiber fusion-spliced on an output side of the amplifying fiber and formed with an OC-FBG having a reflectivity smaller than that of the HR-FBG, an output end, and a mode filter, wherein the input side fiber or an intermediate fiber disposed between the amplifying fiber and the input side fiber is fusion-spliced with the amplifying fiber via a fusion splice portion, and at least a portion of the mode filter is disposed in a region between the fusion splice portion and a position separated from the fusion splice portion by a coherence length of beating caused by mode interference of signal light propagating in the amplifying fiber.

Fiber laser device

A filter device includes: an optical fiber that allows light having a predetermined wavelength to propagate in multimode; a first higher-order mode filter that removes at least part of the light in any higher order mode than a predetermined mode in the light in the multimode propagating in the optical fiber; and a fiber Bragg grating that transmits the light having the predetermined wavelength and reflects light having a particular wavelength longer than the predetermined wavelength.

Filter device and laser apparatus

An optical fiber combinerhas: a plurality of input optical fibers; a plurality of divergence angle reducing memberswhich lights emitted from the respective input optical fibersenter and which emits the lights from the input optical fibersat divergence angles made lower than divergence angles upon entrance; a bridge fiberwhich the lights emitted from the respective divergence angle reducing membersenter and which has a tapered portionwhich has a portion in which the lights propagate and a diameter of which is gradually reduced apart from a divergence angle reducing memberside; and an output optical fiberwhich a light emitted from a side of the bridge fiberopposite to the divergence angle reducing memberside enters.

Optical fiber combiner, and laser system using the same

[Object] An object of the invention is to provide a fiber laser device capable of stabilizing intensity of laser light output therefrom. [Means to attain the object] A fiber laser deviceincludes: an pumping light sourceconfigured to output pumping light; a rare earth-doped fiberto which the pumping light is input; and a first FBGformed on one side of the rare earth-doped fiberand a second FBGformed on the other side of the rare earth-doped fiberthat are configured to reflect light amplified in the rare earth-doped fiber, wherein the second FBGhas a reflectance lower than that of the first FBG, a reflection wavelength band in that of the first FBG, and Bragg wavelength on short wavelength side of Bragg wavelength of the first FBG

There are provided an amplification optical fiber, and an optical fiber amplifier and a resonator using the same capable of outputting light of high beam quality even when a higher-order mode that is axially symmetric is excited in addition to LP01 mode. An amplification optical fiberincludes: a core; a cladcoating the core; and an outer cladcoating the clad, wherein the corehas a larger refractive index than the clad, the coreallows light having a predetermined wavelength to propagate in at least LP01 mode and LP02 mode, and in the core, active element that stimulates to emit light of the predetermined wavelength is doped at a higher concentration at a position where an intensity of the LP02 mode becomes zero than center of the core

Amplification optical fiber, and optical fiber amplifier and resonator using the same

Provided is a fiber laser including a mode filter for selectively attenuating, among modes included in laser light propagating through a multi-mode fiber, any mode other than a radially polarized mode. Among the modes included in the laser light propagating through the multi-mode fiber, the fiber laser causes the radially polarized mode to resonate, so as to emit radially polarized laser light. The mode filter includes a long-period fiber grating obtained by writing, to a multi-mode fiber capable of guiding the radially polarized mode, a grating for selectively attenuating any waveguide mode other than the radially polarized mode.

Laser oscillator and filtering method

A fiber laser light source is provided with a laser resonator including a pair of fiber gratings optically connected to a fiber in a state that the fiber is interposed between the paired fiber gratings. The reflection center wavelength of a laser-exit side fiber grating, out of the paired fiber gratings, lies in a wavelength range where the reflectance of a fiber grating, out of the paired fiber gratings, closer to the pump laser light source is not smaller than 80% but not larger than 98%.

Fiber laser light source

An inner cladding exposure sectionis formed by removing a part of an outer claddingof an optical amplification medium fiberwhich has a porous layerbetween the inner claddingand the outer claddingin a longitudinal direction. An end surfaceof an optical fiberfor the excited light incidence is cemented on an outer periphery of the exposed inner cladding. The excited lightis incident into the optical amplification medium fiberfrom the optical fiberfor the excited light incidence. By doing this, it is possible to provide a method for exciting a light in an optical amplification medium fiber which can realize a superior amplitude while emitting the excited light so as to be incident into the optical amplification medium fiber highly efficiently.

Method for exciting light for optical amplification medium fiber, structure for emitting excited light into optical amplification medium fiber optical fiber amplifier, and optical fiber laser

The invention provides a method and apparatus that precisely and efficiently improves the optical properties of an optical fiber grating. Preferably hydrogen loading processing, grating formation processing that forms a grating part by irradiation with ultraviolet light at a predetermined period, and preferably dehydrogenation, adjusting the optical properties by a suitable combination of uniform ultraviolet irradiation processing that irradiates the grating part as a whole with ultraviolet light and heat trimming processing, and finally heat aging is carried out.

Optical fiber grating, optical fiber grating manufacturing method, and optical fiber grating manufacturing apparatus

An optical fiber grating is manufactured by heating intermittently an optical fiber, provided with a core having residual stress in the longitudinal direction, softening a peripheral cladding of the core, and forming spatial periodical changes for the relative refractive index-difference between the core and the cladding, in the longitudinal direction of the aforementioned optical fiber by having the index of refraction of the core change, through the releasing of the aforementioned residual stress. As a result, an optical fiber grating and the manufacturing method thereof, which do not require expensive equipment and which exhibit high productivity, and furthermore a grating characteristic which is stable over time can be provided.

Optical fiber grating and manufacturing method thereof

Optical fiber grating and manufacturing method therefor

An optical waveguide grating with radiative mode-coupling properties, with exceptional stability and reliability as an optical component, wherein the central wavelength of the rejection band has a low temperature dependence, due to the use of silica glass doped with germanium and boron for the core. The rejection bandwidth can be narrowed without increasing the grating length by forming the radiative mode-coupled optical waveguide grating in an optical waveguide wherein the mean relative refractive index difference of the core is greater than that of optical communication waveguides. The rejection can be increased by reducing the occurrence of cases wherein propagation modes of the core coupled to cladding modes once again couple to the core in palnar optical waveguide gratings formed by making periodic changes in the waveguide structure along the direction of propagation of light in an optical waveguide having a cladding with a lower refractive index than the core surrounding the core, by making the thickness of the cladding at least thirteen times the thickness of the core.

Optical waveguide grating and production method therefor

Core comprises a main stem which is formed on a substrate, linearly extending in the beam propagating direction and short branches with a certain length which extend perpendicularly to the beam propagating direction toward both sides along the plane of the substrate and are arranged at regular intervals in the beam propagating direction. Thus, the branches are arranged in a ladder geometry when it is viewed from the top, forming a rectangular waveform arrangement. The core constitutes a grating structure in which the width of the core is made to vary periodically with the branches in the beam propagating direction.

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Sakura, Japan

Kensuke Shima