Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
1998-08-26
2001-08-07
Spyrou, Cassandra (Department: 2872)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S014000, C385S049000, C385S052000
Reexamination Certificate
active
06270263
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an optical module used for optical communication.
BACKGROUND ART
Conventionally, optical modules for optical communication can be classified into two types, a coaxial pigtail type, which is based on a can type and in which an optical waveguide, e.g., an optical fiber, and a semiconductor optical element are connected optically to each other through a lens, and a receptacle type in which an optical fiber can be attached or detached by means of a connector. Further, pump lasers or laser diode modules of a distribution-feedback type for optical fiber amplifiers include butterfly-type pigtail modules that include a cooler using a Peltier element. In order to obtain high reliability, in this case, the modules of the two types employ a hermetically sealed structure of metal or ceramics. An optical waveguide component, e.g., an optical fiber, receives light from a light emitting element, and is fixed to a module by soldering or YAG-laser welding when the quantity of light projected with the optical fiber being aligned attains a desired value.
On the other hand, optical modules of a new type have been developed in order to meet a demand for the reduction of costs to realize modern optical subscriber systems. An example is disclosed in the Telecommunications Society-Electronics Society Meeting Drafts C-296, 1996, for instance.
This optical module is characterized by being of a plane mounting type such that a dual inline (DIL) is used for a package.
In this optical module, a laser diode (hereinafter referred to as “LD”) is mounted highly accurately on a silicon substrate through picture recognition. A short optical waveguide component, such as an optical fiber, is fixed nonaligned by utilizing a V-groove on the side of light emission from the LD of the substrate. This optical module can be easily sealed by means of a resin adhesive agent. An end portion of the optical fiber may be of a detachable type based on a connector interface or of a pigtail type.
However, the aforesaid module has the following problems. In order to couple the optical waveguide component, such as an optical fiber, accurately to an optical element, the V-groove(s) of the silicon substrate must be worked with high accuracy of about 0.5 &mgr;m. If the optical fiber is a single fiber, the silicon substrate requires only one V-groove. In the case where a plurality of optical fibers are coupled to a plurality of semiconductor optical elements, however, a plurality of V-grooves must be worked with high accuracy.
Conventionally, a wet-etching method based on a potassium hydroxide solution or the like is used to work V-grooves on silicon substrates.
According to this method, however, the substrates are etched very dispersedly, so that it is hard uniformly to work fine V-grooves. In the case where a plurality of V-grooves are all worked uniformly, in particular, the yield of the resulting substrates is low. Moreover, the optical fibers, e.g., single-mode fibers, are fine, having diameters as small as about 125 &mgr;m, so that they cannot be handled with ease when they are positioned in the V-grooves of the silicon substrate. In positioning a plurality of optical fibers, such as tape fibers, in their corresponding V-grooves, in particular, the optical fibers are arranged so disorderly that they cannot be easily fixed to the V-grooves unless force is applied equally to every optical fiber.
The present invention has been contrived in consideration of these circumstances, and its object is to provide optical modules, which can be assembled with ease and of which substrates can be manufactured with good yield, whereby optical waveguide components, such as optical fibers, and semiconductor optical elements are coupled optically.
DISCLOSURE OF THE INVENTION
In order to achieve the above objects, according to the present invention, there is provided an optical module comprising a substrate, formed with wiring patterns for electrical signals and having a mounting surface mounted with one or more semiconductor optical elements, and a package in which the substrate is located, in which the substrate is formed with at least one first positioning section, the package is formed of a synthetic resin and includes a disposition section in which one or more optical waveguide components are opposed to the semiconductor optical elements, and a second positioning section adapted to engage the first positioning section, thereby positioning the semiconductor optical elements and the disposition section.
Preferably, the first positioning section is a V-groove formed in the mounting surface, and the second positioning section is a ridge.
Preferably, moreover, the optical waveguide component is an optical fiber, and the disposition section is a fiber hole.
Preferably, furthermore, the optical fiber is fixed to the fiber hole in a manner such that one end thereof projects toward the semiconductor optical element for 1 to 1,000 &mgr;m.
Preferably, the clearance between the fiber hole and the optical fiber at each end thereof ranges from 0.1 to 0.8 &mgr;m.
Preferably, moreover, the substrate is formed of silicon, silicon oxide, aluminum oxide, or aluminum nitride.
Preferably, furthermore, the package is composed of first and second sections.
Preferably, the package is a tubular body having the disposition section formed in the front portion thereof and having the rear portion thereof open.
Preferably, moreover, the package includes a ferrule of ceramics or glass partially molded with a synthetic resin.
The synthetic resin that constitutes the package is not limited to any specific material only if it ensures high dimensional accuracy for molding. Usually, for example, it is a resin composition prepared by blending 100 parts by weight of a synthetic resin with 30 to 40 parts by weight of a filler. In the case of a filler-rich type (case of polyphenylene sulfide (PPS)), a resin component used is prepared by blending 100 parts by weight of a synthetic resin with 30 to 300 parts by weight of a filler.
Available synthetic resins for these resin compositions include, for example, polyphenylene sulfide (PPS), liquid crystal plastic (LCP), totally aromatic polyester, polybenzimidazole (PBI), polyether-ether ketone (PEEK), polyether imide (PEI), polyether nitrile (PEN), polyether sulfone (PES), epoxy resins, etc.
The filler may be formed of any of free combinations of the aforesaid synthetic resins and silica, carbon, glass fibers, carbon fibers, aramid fibers, glass beads, etc.
In the optical module according to the present invention, the substrate can be positioned with respect to the package in a manner such that the first positioning section is caused to engage the second positioning section, and the semiconductor optical element and the disposition section, and therefore, the semiconductor optical element and the optical waveguide component, such as an optical fiber, can be positioned with high accuracy.
REFERENCES:
patent: 4402568 (1983-09-01), Kulich et al.
patent: 5463708 (1995-10-01), Yui et al.
patent: 5-323159 (1993-12-01), None
patent: 7-63956 (1995-03-01), None
patent: 07294777A (1995-10-01), None
Iwase Masayuki
Mori Hajime
Shigematsu Takashi
Curtis Craig
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Spyrou Cassandra
The Furukawa Electric Co. Ltd.
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