Sumitomo Electric Industries, Limited

Sumitomo Electric Optifrontier Co., Ltd.

Okayama University

Shigehiro Nagano

Takemi Hasegawa

Motoki Kakui

Jun Kinugasa

Manabu Shiozaki

Shinobu Tamaoki

Hiroshi Kohda

Yasuomi Kaneuchi

Tetsuya Hayashi

Masakazu Shigehara

Yoshiaki Tamura

Hirotaka Sakuma

Masayuki Yamazaki

Yoshiyuki Uno

Yasuhiro Okamoto

Kenta Takahashi

Kazuaki Masui

A gain flattening filter includes a first optical fiber that has a core, a first cladding, and a second cladding and that has a uniform composition in a length direction; and a pair of second optical fibers fused to both ends of the first optical fiber. The first optical fiber has a first section in which a slanted refractive index grating is formed and a pair of second sections connecting both ends of the first section to the pair of second optical fibers. The first cladding contains a photosensitive material whose refractive index increases upon irradiation with light having a specific wavelength. In the core, a tensile stress remains in the first section. An average MFD of the second sections is larger than an average MFD of the second optical fibers and smaller than an average MFD of the first section.

Gain flattening filter, and method for manufacturing gain flattening filter

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 &#x3bc;m in the third region is smaller than an MFD at a wavelength of 1.55 &#x3bc;m in the first region.

Slant-type fiber grating

The present embodiment relates to an optical amplifier and the like having a structure for enabling efficient use of pumping light while avoiding complication of a device structure. In such an optical amplifier, since pumping light from a pumping light source is supplied to each core of an amplification MCF, a coupling MCF in which adjacent cores form a coupled core is arranged between the amplification MCF and the pumping light source. The pumping light source is optically connected to a specific core of the coupling MCF, and pumping light is coupled from the specific core to remaining cores except the specific core in the coupling MCF before pumping light is supplied to each core of the amplification MCF. This enables coupling of pumping light between optically connected cores between the amplification MCF and the coupling MCF.

Optical amplifier and multi-core optical fiber

An object is to provide, for example, an optical wavelength conversion device capable of highly efficient wavelength conversion on the surface of, or inside, the main body of any of various shapes, such as a bulky shape and a fiber shape. The optical wavelength conversion device includes a main body configured to allow light to propagate therein, and a plurality of crystal regions arranged inside the main body along a propagation direction of the light. The plurality of crystal regions each have a spontaneous polarization oriented along the propagation direction (i.e., spontaneous polarization having a polarization orientation coinciding with the propagation direction).

Optical wavelength conversion device

An optical fiber according to an embodiment includes a core having a single-peaked and graded refractive index profile, an inner cladding surrounding the core, and an outer cladding surrounding the inner cladding. The inner and outer claddings have refractive indices lower than the maximum refractive index of the core. A photosensitive region constituted by the core and the inner cladding contains a photosensitive material. The inner cladding has an outer diameter one time or more and two times or less the MFD of an LPmode in a 1310-nm wavelength band.

Optical fiber and optical fiber grating

An optical fiber is made of silica-based glass and includes a core, a first cladding that surrounds the core and that has a refractive index lower than a refractive index of the core; and a second cladding that surrounds the first cladding and that has a refractive index lower than the refractive index of the core and higher than the refractive index of the first cladding. At least a part of the first cladding contains a photosensitive material whose refractive index increases by irradiation with light having a specific wavelength. A difference &#x394;n between a refractive index of a portion of the first cladding, the portion being nearest to the core, and the refractive index of the core is in a range of 0.25% to 0.30%. The radius ra of the core is larger than 4.3 &#x3bc;m and smaller than or equal to 5.0 &#x3bc;m.

Optical fiber and slanted fiber grating

An embodiment of the invention relates to an optical device which is capable of realizing a secondary nonlinear optical phenomenon. The optical device is a fiber-type optical device which is comprised of glass containing SiO, and includes a core region, a first cladding region, and a second cladding region. At least a part of a glass region configured by the core region and the first cladding region has such a repetition structure that a first section serving as a poled crystal region and a second section serving as an amorphous region are alternately disposed along a longitudinal direction of the optical device.

Optical device and method for manufacturing optical device

An object is to provide, for example, a method for manufacturing an optical wavelength conversion device having a structure that enables efficient formation of crystal regions on the surface of, or inside, an amorphous material. An amorphous main body is intermittently irradiated with a first laser beam for generating a high-density excited electron region inside the main body and a second laser beam for heating the high-density excited electron region, with respective focus regions of the first and second laser beams overlapping each other. During the intermittent irradiation with the first and second laser beams, the relative position of the main body and the overlapping focus region of the first and second laser beams are varied. This enables part of the main body where the overlapping focus region moves to serve as a heat source for forming a crystal region.

Optical wavelength conversion device and method for manufacturing the same

Optical device including poled crystal region and amorphous region

The present embodiment relates to an MCF and the like suitable for fabricating an FBG with improved ripple characteristics. The MCF is mainly composed of silica glass, and comprises a plurality of light guiding structures and a common cladding. Each of the light guiding structures includes a core, a first cladding, and a second cladding. The refractive index of the second cladding is higher than that of the first cladding and is lower than those of the core and the common cladding. Further, at least a part of an inner cladding region, constituted by the first cladding and the second cladding, contains a photosensitive material having photosensitivity of changing a refractive index of a glass region containing the photosensitive material in response to irradiation of light with a specific wavelength.

Multicore optical fiber with a core and a common cladding having a higher refractive index than the core, fiber Bragg grating, and method for manufacturing fiber Bragg grating

The present invention relates to a laser light source which reduces wavelength-dependent difference of focal position of condensed light when multicolor light with a wide spectral width is collimated and then condensed. The laser light source incorporates a collimator device, in which an installation position of a collimating lens with respect to a laser light entrance portion is set so that a beam waist position of laser light having passed through the collimating lens shifts closer to the collimating lens with a shorter-wavelength-side wavelength component out of wavelength components included in the laser light.

Laser light source

The present invention relates to a laser light source capable of suppressing variation in propagation state of randomly-polarized laser light. In the laser light source, an isolator including a Faraday rotation crystal having a positive thermooptic constant, and a nonlinear optical crystal having a negative thermooptic constant are arranged in order along a traveling direction of laser light. The nonlinear optical crystal is arranged in a state off normal incidence of incident light so that a propagation axis of light propagating in the crystal is parallel to an optic axis of the crystal.

There is obtained a laser processing method by which an excellent shape of a cut surface can be achieved and an increase in cost can be suppressed. A laser processing method includes the steps of: preparing a material to be processed; and forming a modified area in the material to be processed, by irradiating the material to be processed with laser beam. In the aforementioned step, pulsed laser beam having a continuous spectrum is focused with a lens, thereby forming a focusing line constituted by a plurality of focuses that are obtained by predetermined bands forming the continuous spectrum of the laser beam, and the material to be processed is irradiated with the laser beam such that at least a part of the focusing line is located on a surface of the material to be processed, thereby forming the modified area on an axis of the focusing line.

Laser processing method

The present invention relates to a laser light source and others for decreasing wavelength-by-wavelength differences of focal positions of focused components in collimating and then focusing polychromatic light with a wide spectrum width. The laser light source includes a collimator device, in which relative positions of emergence of a laser beam emitted from a polychromatic light source and a collimating lens composed of an achromatic lens can be adjusted at a 10 &#x3bc;m level or less.

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Yokohama, Japan

Shigehiro Nagano