Fujikura Limited

Fujikara Ltd.

Tetsuya Sakai

Akira Wada

Ryozo Yamauchi

Tomoharu Kitabayashi

Michihiro Nakai

Kensuke Shima

Satoshi Okude

Tetsuo Nozawa

Takeshi Segi

Daiichirou Tanaka

Hiroshi Hidaka

Kenji Nishide

Takuya Aizawa

Shigefumi Yamasaki

Takafumi Kashima

Masaaki Sudoh

Nobuyuki Tanaka

Kuniharu Himeno

Shoji Tanigawa

Hironori Tanaka

Ryo Sugimoto

Noriaki Shimada

Yasuko Kobayashi

Yasushi Takeda

Yasuyuki Okada

Manabu Saito

Takuya Ienaka

This fiber laser is provided with: a signal light source that outputs a signal light; a rare earth-doped fiber that amplifies and outputs the signal light from the signal light source; a Raman amplifying fiber that is routed as a portion of an optical transmission path in order to output the output light from the rare earth-doped fiber to an outside thereof; and a wavelength selecting element that is provided in the optical transmission path from the Raman amplifying fiber to the signal light source and does not allow transmission of a Stokes light that is generated in the Raman amplifying fiber.

Fiber laser

A MO-PA type optical amplifier is provided which includes an oscillator and an amplifier including a fiber for optical amplification, including: a reflected-light wavelength conversion fiber which is provided on an optical path between the oscillator and the amplifier and which converts a wavelength of reflected-light traveling toward the oscillator due to Stimulated Raman Scattering; and a filter which is provided on the optical path between the oscillator and the amplifier and which eliminates the wavelength-converted light.

Optical amplifier, fiber laser, and method of eliminating reflected light

An optical pumping device is provided in which a multi-core fiber obtained by bundling up a plurality of optical fibers, which are input ports, and a double clad fiber for optical pumping are spliced through a bridge fiber composed of a double clad fiber having a tapered shape. Accordingly, it is possible to efficiently couple signal light and pumping light to the double clad fiber for optical pumping.

Optical pumping device, optical amplifier, fiber laser, and multicore fiber for optical pumping device

A multi-port coupler for coupling an pumping light source to a cladding pump fiber for optical amplification, includes a central signal fiber and a plurality of pumping fibers arranged around the central signal fiber, the central signal fiber and the plurality of pumping fibers being unified and a front side is reduced in diameter, wherein an emitted light confining waveguide part is provided around a core of the signal fiber located at the center, and the emitted light confining waveguide part whose outer diameter is larger than that of the core has a higher refractive index than a cladding and a lower refractive index than the core and the emitted light confining waveguide part is formed continuously from a splicing point of the cladding pump fiber to a coupler front end branched into multiple fibers.

Multi-port coupler, optical amplifier, and fiber laser

An end face structure of an optical fiber includes a coreless fiber fused to an emitting end face of the fiber optical fiber and a coating material disposed around at least the coreless fiber, a refractive index of the coating material being higher than a refractive index of the coreless fiber.

End face structure of optical fiber, optical fiber laser, and laser processing apparatus

An optical fiber laser includes a resonator comprising an erbium-doped glass fiber serving as a gain medium and a pumping light source that launches pumping light into the erbium-doped glass fiber. The pumping light source emits pumping light of a wavelength of 980 nm or longer, and the optical fiber laser emits laser light in a wavelength band of 2.8 &#x3bc;m (2.7 &#x3bc;m to 3.0 &#x3bc;m).

Optical fiber laser and laser light emitting method

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

An optical fiber coupling structure for optically coupling an emission-side optical fiber and an incidence-side optical fiber includes: an emission-side base; and an incidence-side base, wherein the emission-side optical fiber is secured to the emission-side base, and an end of the emission-side optical fiber is exposed at the coupling end surface, wherein the incidence-side optical fiber is secured to the incidence-side base, and an end of the incidence-side optical fiber is exposed at a slope provided in said incidence side base, and wherein the coupling end surface of the emission-side base is abutted against the abutting surface of the incidence-side base, the emission-side optical fiber exposed at the coupling end surface of the emission-side base and the incidence-side optical fiber exposed at the slope of the incidence-side base are spaced apart with a clearance, and the emission-side optical fiber and the incidence-side optical fiber are optically coupled.

Optical fiber coupling structure and method for coupling optical fibers

A method for detecting a connector disengagement of an optical fiber amplifier and a transmission optical fiber connected thereto, the optical fiber amplifier including a doped optical fiber and a pumping light source, and a transmission optical fiber including at least one connecting portion connected to an output of the optical fiber amplifier, includes the steps of: measuring a reflection from the transmission optical fiber to the optical fiber amplifier; and comparing the reflection to an allowable range between a first threshold that is greater than a predetermined reflection in the absence of a connector disengagement, and a second threshold that is smaller than the predetermined reflection in the absence of a connector disengagement; determining that there is no connector disengagement when the measured reflection is within the allowable range; and determining that there is a connector disengagement otherwise.

Method for detecting disengagement of an optical fiber, an optical fiber amplifier, and a unit of an optical fiber amplifier with a transmission optical fiber

An optical amplifier has a gain flatness which is maintained to be substantially constant regardless of temperature changes. The optical amplifier includes an EDF amplifying section and a Raman amplifying section, the Raman amplifying section having a temperature dependent gain profile which enables compensating for the temperature dependent gain profile of the EDF amplifying section. The Raman amplifying section includes a wavelength lock grating whose transmission wavelengths shift toward the short wavelength side as the temperature increases. The wavelength lock grating is preferably disposed to have the same temperature as that of an EDF of the EDF amplifying section. A method for compensating for temperature dependency of gain flatness of an optical amplifier and an optical transmission path including an optical amplifier are also disclosed.

Optical amplifier, method for compensating for temperature dependency of gain flatness of an optical amplifier and optical transmission path including optical amplifier

An optical fiber amplifier having improved gain and reduced noise, and an optical amplifier which restrains an unnecessary polarization component in the signal output light, maintains polarization of a signal light and performs optical amplification in which a polarizer is connected between a first optical fiber and a second optical fiber. An amplified spontaneous emission is emitted from the output end of the first fiber with the amplified signal light and is incident to the polarizer. The polarizer is disposed so as to transmit a polarization component which is parallel with the signal light. Among the different light components which are incident to the polarizer, a light having a polarization component which is orthogonal with the signal light is rejected.

Polarization maintaining optical fiber amplifier and optical amplifier

An optical fiber amplifier comprises an optical fiber for light loss which is provided in a later stage than an optical fiber amplification section or midway therein, the amount of light absorption and the wavelength dependency of the absorption of the optical fiber changing according to the power of input light; whereby the optical fiber amplifier can maintain flat gain in a wide wavelength band, the gain flatness not changing over a wide dynamic range and being maintained irrespective of variation in the power of input signal light.

Gain tilt free optical fiber amplifier in a wide dynamic gain range

In an optical amplifier using a rare earth element-doped optical fiber such as an erbium-doped optical fiber, a variation of amplification gain resulting from temperature change is suppressed and the gain-temperature characteristic is enhanced. Moreover, the quantity of temperature compensation in the gain is easily adjustable. Light from an excitation light source is input to an optical fiber for optical amplification comprising a rare earth element-doped optical fiber, via a temperature compensation optical fiber comprising a rare earth element-doped optical fiber such as an erbium-doped optical fiber. By changing the length of this temperature compensation optical fiber, the quantity of temperature compensation is finely adjusted.

Optical amplifier utilizing rare earth element-doped optical fibers for temperature compensation

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.

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Sakura, Japan

Tetsuya Sakai