Fujitsu Corporation

Koji Okamura

Tadao Arima

Keiko Takeda

Norifumi Shukunami

Shinya Inagaki

Akira Okamoto

Takayuki Masuko

Kaoru Moriya

Takeshi Akamatsu

An optical amplifying fiber including a clad, a first core provided inside the clad and containing Ge, a second core provided inside the first core and containing Er and Al, and a third core provided inside the second core and containing Ge. The second core has a refractive index higher than that of the clad, and the first and third cores have refractive indexes each of which is higher than that of the second core. Since the third core having the high refractive index is provided at a central portion, it is possible to make smaller a mode field diameter and hence to improve a conversion efficiency of pumping light into signal light. Further, since the second core contains Al as an amplification band width increasing element, it is possible to sufficiently ensure a wide amplification band width.

Solution doping method of making an optical amplifying fiber

An optical amplifying fiber including a center core region doped with erbium, aluminum, and phosphor, and a ring region doped with erbium and aluminum, the ring region being radially spaced a given distance from the center core region.

Optically amplifying fiber and optical fiber amplifier

Optical amplifying fiber and process of producing the same

A method of manufacturing an optical module for wavelength-division multiplex optical transmission, which module comprises a first optical fiber having a first port at its one end and a second and a third optical fiber fused to the first optical fiber at its side face such that the first optical fiber is positioned in the center between the second and third optical fibers. The manufacturing method comprises a first step of regulating the aspect ratio at the fused portion while heating the fused portion and elongating the fused portion at zero speed or a very low speed and a second step of regulating the coupling length of the fused portion while elongating the fused portion at a higher speed than in the aspect ratio regulating step under the conditions of the heating temperature of the fused portion lowered and the aspect ratio kept unchanged.

Method of manufacturing an optical module for wavelength division

A star coupler for interconnecting optical fibers to distribute optical signals. The method for fabricating the star coupler comprises the steps of preparing a tubular member and first and second groups of optical fibers having bare fiber portions extending from the ends. The bared fiber portions of the first and second groups of optical fibers are inserted into the tubular member, in the opposite directions, in an end-to-end abutting relationship. The contacting ends of the bared fiber portions are then molten and fused together. The fused fiber portions are finally stretched together with the tubular member. It is possible to preheat the tubular member at a relatively low temperature so that the tubular member shrinks relative to the bared fiber portions to retain the latter. The obtained star coupler comprises first and second groups of optical fibers inserted into a tubular member in an end-to-end abutment relationship, with the ends joined together. The tubular member has an inner surface in a generally polygonal shape.

Method for fabricating star coupler for interconnecting optical fibers

Disclosed is a polarization-splitting fiber coupler capable of stably executing a polarization separation/coupling and a method of stably manufacturing the polarization-splitting fiber coupler at a low cost. The method comprises the steps of (1) arranging a plurality of non-polarization fibers in parallel so that the side surfaces thereof come into contact to each other; (2) heating and fusing a portion of the arranged non-polarization fibers by controlling a heating temperature and a heating time so that the cross section of the fused portion thereof has an aspect ratio of 1.85-1.95; (3) thereafter, forming a fused/drawn portion by drawing the fused portion while keeping the aspect ratio after lowering the heating temperature; and (4) connecting polarization-maintaining fibers to the respective ends of the fused/drawn portion, respectively. Further, a portion of the connected polarization-maintaining fiber is heated and drawn to a taper-shape to provide the heated-fused portion with a polarizer function.

Polarization-splitting fiber coupler and method of making same

Disclosed are a planar wave guide type optical amplifier for amplifying a light signal passing through an optical fiber, a method of manufacturing the above light amplifier, and a laser oscillator using the light amplifier, The planar wave guide type optical amplifier comprises a first core formed to a bar shaped on a substrate and a light amplifying region composed of a part of the first core, having a configuration extending to the longitudinal direction of the first core, and doped with a rare earth element. The method of manufacturing the planar wave guide type optical amplifier comprises the steps of (1) forming a bar-shaped core on a plane substrate, (2) forming a groove to the core which extends to the longitudinal direction thereof, (3) filling the groove with a filler doped with a rare earth element and (4) solidifying the filler. The laser oscillator comprises a first core formed to a bar shape on a substrate, a light amplifying region composed of a part of the first core, having a configuration extending to the longitudinal direction of the first core, and doped with a rare earth element, and light reflecting means provided with the opposite ends of the first core, respectively,

Planar wave guide type optical amplifier

A method for fabricating a waveguide type optical device is disclosed, through which a core and a reference plane are obtained at the same time by etching a core layer using a thin layer of a predetermined shape formed on the core layer as a mask. In this waveguide type optical device, the core is easily coupled with an optical element such as an optical fiber by means of the reference plane.

Waveguide type optical device and method for manufacturing the same

A photo-semiconductor module is disclosed wherein a reliable airtight condition can be obtained and an operability in assembly can be improved. The photo-semiconductor module comprises a substrate carried in a casing, a photo-semiconductor chip mounted on the substrate, and a support member carried on the substrate and having an inclined face which is inclined by an angle of 45 degrees with respect to a surface of the substrate. A semi-spherical lens is securely mounted on the inclined face of the support member, and an opening formed in a side wall of the casing is sealed airtight by a glass member while an upper portion of the casing is sealed airtight by a lid. When an optical fiber is mounted onto the casing such that an end face thereof may be located in the opening in the side wall of the casing, the optical fiber and the photo-semiconductor chip are optically coupled to each other by way of the semi-spherical lens.

Photo-semiconductor module employing semi-spherical lens to enhance

An improved method of producing an optical fiber with a low transmission loss for use in an optical communication system. The method comprises a chemical vapor deposition process wherein starting materials in gas phase are oxidized to form a soot on a glass substrate, and the soot which deposits on the substrate is vitrified in an atmosphere of an inert gas which is easily dissolved in the vitrified glass. A preferable soot contains silicon dioxide, a first dopant for effecting an increase of the refraction index of the silicon dioxide and a second dopant for effecting a reduction of the vitrification temperature of the soot.

Growing community of inventors

Kawasaki, Japan

Koji Okamura