Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Corporation

Toru Iwashima

Masakazu Shigehara

Akira Inoue

Michiko Harumoto

Shinji Ishikawa

Kiyotaka Murashima

Masayuki Nishimura

Hiroshi Suganuma

Toshiaki Okuno

Makoto Katayama

Masayuki Shigematsu

Tomomi Sano

Manabu Shiozaki

Masumi Ito

Yoshiaki Terasawa

Tomohiko Kanie

Shigeru Semura

Yoshiaki Miyajima

Tetsuya Hattori

Ken Hashimoto

Shin-ichi Furukawa

Toshinori Wakami

Michiko Takushima (nee Harumoto)

An optical signal, which is to become the subject of dispersion compensation, is split by optical combining/splitting unit, and each frequency component of the optical signal that is split is reflected by the corresponding reflective mirrorincluded in reflective mirror groupto apply a predetermined phase shift to the respective frequency components Each reflected frequency component is then combined using optical combining/splitting unit, to give dispersion compensated optical signal Furthermore, in regards to reflective mirror group, which is used to apply phase shift to each frequency component of an optical signal, each of the respective plurality of reflective mirrorsis made a movable mirror having a movable reflection position that reflects the frequency components. Through this, dispersion that develops in an optical signal may be compensated with favorable controllability and high accuracy. Therefore, the precision and controllability of dispersion compensation will become superior, and realized is a variable dispersion compensator having a miniaturized optical circuit, and an optical transmission system comprising such variable dispersion compensator,

Variable dispersion compensator and optical transmission system

In a diffraction grating device (), index modulations are formed along the longitudinal direction of an optical fiber () serving as an optical waveguide. The optical fiber () has a core region (), an inner cladding region (), and an outer cladding region () sequentially from the optical axis center. Index modulations are formed in both the core region () and the inner cladding region () of the optical fiber () in each of a plurality of regions Ato A(N is an integer; N&#x2267;2) separated from each other along the longitudinal direction of the optical fiber (). In the diffraction grating device (), regions A(n=1 to N) in which index modulations are formed in both the core region () and the inner cladding region () and regions B(n=1 to N&#x2212;1) in which no index modulations are formed alternately exist along the longitudinal direction.

Diffraction grating device

The present invention provides a method for determining a condition of aging for an optical waveguide grating. In this method, the aged deterioration,curve of the optical waveguide grating is set as a forms of C&middot;t , t represents time, and &agr; and C represent parameters. Then, the condition of the aging is determined based on the aged deterioration curve.

Method for determining an aging condition for an optical waveguide grating and temperature sensor

This invention relates to a diffraction grating device having a refractive index modulation formed in an optical waveguide region in a predetermined region in the longitudinal direction of the optical waveguide. In the diffraction grating device, a refractive index modulation is formed in the core region in a predetermined region in the longitudinal direction of the optical waveguide. In this diffraction grating device, the optical period of the refractive index modulation is substantially constant, the phase of the refractive index modulation is inverted at a phase inversion portion, and the number of phase inversion portions is one or two. In this diffraction grating device, the absolute value of a parameter R (equation ( )) is smaller than . According to this invention, a diffraction grating device capable of shortening the region where the refractive index modulation is formed and flattening the reflectance characteristic in the reflection wavelength band is provided.

The present invention concerns an optical waveguide device having a structure for effectively suppressing variation in optical characteristics due to temperature change without causing increase in device size, and a fabrication method thereof. The optical waveguide device has a structure in which a first main member having a positive coefficient of linear expansion is fixed to a sub member having a negative coefficient of linear expansion. The first main member is provided with an undercladding, a core functioning as an optical waveguide provided on a plane of the undercladding, and an overcladding provided so as to cover the core between the undercladding and the overcladding. The first main member is made, for example, of a silica glass or silicon based material and the core is doped with a dopant for increasing the refractive index. While covering the whole of at least one major surface of the first main member, the sub member is fixed to the major surface.

Optical waveguide devices and methods of fabricating the same

The present invention provides a method for determining a condition of aging for an optical waveguide grating. In this method, the aged deterioration curve of the optical waveguide grating is set as a form of C&middot;t,, where t represents time, and &agr; and C represent parameters. Then, the condition of the aging is determined based on the aged deterioration curve.

The present invention provides a method for determining a condition of aging for an optical fiber grating. This method comprises a step of setting the aged deterioration curve of the optical fiber grating as a form proportional to t.sup.-n, where t represents time, and n represents a parameter dependent on temperature; and a step of determining the condition of the aging according to the aged deterioration curve.

Method for determining a condition of aging for optical fiber grating

In an optical filter formed with a grating whose refractive index fluctuates along an optical axis of an optical waveguide so as to reflect light in a predetermined wavelength band, assuming that a position in the grating area is defined by a positional coordinate value z which is standardized by -.pi. to .pi. in a light propagating direction, an amplitude .DELTA.n of refractive index changing width in z satisfies: ##EQU1## by use of predetermined parameters x.sub.1 and x.sub.2 and proportional constants k.sub.1 and k.sub.2, .DELTA.n monotonously increasing or decreasing depending on whether the expression -.pi..ltoreq.z.ltoreq.0 or 0.ltoreq.z.ltoreq..pi. is satisfied, respectively.

Optical filter

Optical fiber diffraction grating, a method of fabricating thereof and a

A band-pass filter formed in an optical waveguide, provided with a diffraction grating group having a period .LAMBDA. of refractive index fluctuation changing in an axial direction with substantially a constant changing width .DELTA.n, comprises two periodic refractive index variable areas having periodes .LAMBDA. different from each other; a zero area, disposed therebetween, having substantially a constant refractive index; and boundary areas, disposed between the zero area and the respective periodic refractive index variable areas, in which the changing width of refractive index monotonously changes between 0 and .DELTA.n.

Diffraction grating type band-pass filter and method of making the same

The optical connector according to the present invention comprises, at least, an optical filter with a waveguide structure having a grating with a predetermined reflection wavelength and a plug attached to a tip of the optical filter. The grating is disposed at a tip portion of the optical filter and accommodated in the plug attached to the tip portion of the optical filter. Further, the optical connector has various light-blocking structures for preventing unnecessary light from traveling a filter region of the optical filter including the grating.

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Yokohama, Japan

Toru Iwashima