Glass manufacturing – Processes of manufacturing fibers – filaments – or preforms – Process of manufacturing optical fibers – waveguides – or...
Reexamination Certificate
2000-02-25
2002-08-20
Colaianni, Michael (Department: 1731)
Glass manufacturing
Processes of manufacturing fibers, filaments, or preforms
Process of manufacturing optical fibers, waveguides, or...
C065S102000, C065S106000, C065S111000, C065S404000, C065S408000
Reexamination Certificate
active
06434976
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a molding method capable of molding a glass product with high precision of a fine structure without creating molding burrs, even if the glass product has a weak symmetry as of an optical fiber fixing member and the fine structure such as an optical fiber engagement portions.
2. Description of Related Art
An optical fiber used for optical communication is generally a fine glass fiber. For example, a quartz single mode optical fiber used for long distance optical communication is constituted of a core having an outer diameter of about 10 micron meters and a clad covering the core and having an outer diameter of 125 micron meters. A quartz multi-mode optical fiber is constituted of a core having an outer diameter of 50 to 100 micron meters and a clad covering the core and having an outer diameter of 125 micron meters. Accordingly, high alignment precision is required to reduce a connection loss at optical connecting points when optical fibers are optically connected to each other or when an optical fiber is optically connected to an optical device such as an optical waveguide, a lens, an light emitting device, a photo-receiving device, etc. In particular, optical connections between quartz single mode optical fibers and between a quartz single mode optical fiber and a quartz glass single mode optical waveguide require a high alignment precision of around ±1 micron meter.
To optically connect an optical fiber with another optical fiber or optical device, the optical fiber is fixed in advance by an optical fiber fixing member such as an optical connector or optical fiber array. The optical fiber array here means a member at least including an optical fiber guide block and a fiber fixing lid. The optical fiber guide block is made of a thin plate formed with engagement portions for fixing optical fibers to position the optical fibers. The fiber fixing lid is made of a thin plate for pressing the optical fibers engaging with the engagement member to fix the optical fibers. For example, Japanese Unexamined Patent Publication, Heisei No. 7-5,341 discloses an optical fiber array for fixing a tape fiber in which plural optical fibers arranged in a row are protected by a resin cover. This optical fiber array is shown in FIG.
7
.
As shown in
FIG. 7
, the optical fiber array
200
includes an optical fiber guide block
204
and a fiber fixing lid for optical fibers
205
. The optical fiber guide block
204
is a block in a thin plate shape on which a prescribed number of V-shaped grooves
203
serving as engagement portions for fixing optical fibers are formed for fixing optical fibers
202
striped from a tape fiber
201
. The fiber fixing lid
205
for optical fibers is a block in a thin plate shape to press the optical fibers to fix the optical fibers
202
engaged with the V-shaped grooves
203
. The optical fiber guide block
204
constituting the optical fiber array
200
has, in addition to the V-shaped grooves
203
, a seat
207
for fixing a covered portion
206
of the tape fiber
201
. The seat
207
is formed at a position lower than the V-shaped grooves
203
. The optical fiber array
200
includes a fiber fixing lid
208
having a prescribed cross section to securely hold the covered portion
206
fixed at the seat
207
.
To optically connect optical fibers fixed by optical fiber fixing members such as optical connectors and optical fiber arrays with each other or connect optical fibers fixed by an optical fiber fixing member with an optical device under a high alignment precision, an active alignment is conventionally used in using a precision stage. The active alignment is implemented in the following manner, for optical fibers fixed by optical fiber arrays and connected with each other.
First, an optical fiber array to which optical fibers are fixed (hereinafter referred to as “optical fiber array A”) is fixed to a holder on a precision stage, and another optical fiber array to which optical fibers are fixed (hereinafter referred to as “optical fiber array B”) is fixed to another holder on the precision stage. Light is made to enter in an optical fiber fixed on the optical fiber array A from an optical fiber end in opposition to an optical connection side end (end positioned on a side where the optical fiber array is connected to another optical fiber array or optical device, between the opposing ends of the optical fiber) of the optical fiber array A, and an optical detector is set at an end located in opposition to the optical connection side end in the optical fiber array B. Then, the precision stage is scanned over a wide range to explore a position at which the optical detector detects optical power even of a small amount (this stage is referred to as “first step”). Then, the precision stage is scanned by a very small distance as to pick up the maximum optical power by the optical detector, thereby obtain the aimed high precision alignment (this stage is referred to as “second step”).
Because a considerable time is required to scan the stage over the wide range at the first step during the active alignment, it is desirable to substantially complete the first step when the optical fiber fixing member is fixed to the stage's holder to make the high precision alignment easy. To do so, it is desired that the optical fiber engagement portions on the optical fiber fixing member is built with high precision, as well as that the optical fiber engagement portions are built with high precision such that positional precision, when measured in reference with the bottom face or side face of the optical fiber fixing member, are within {fraction (1/10)} or less of the core diameter of the optical fibers to optically connected in use of the optical fiber fixing member. For example, in the case where quartz single mode optical fibers having a core diameter of around 10 micron meters are optically connected to each other, or in the case where a quartz single mode optical fiber is connected to a quartz glass single mode optical waveguide, the positional precision is desirably within 10 micron meters or less, and if the positional precision is within 5 micron meters or less, the alignment can be done easily.
When the position precision is reduced to about {fraction (1/10)} or less of the core diameter of the optical fibers, the fibers can be optically connected by a passive alignment. The passive alignment is an alignment method for mechanically adjusting the positions of the optical fiber fixing members or the fixing member and an optical device, using the side or bottom faces of the optical fiber fixing members as reference faces without detecting light entering into and emerging from the optical fibers. Thus, the optical fiber fixing members such as optical fiber arrays are required to have a high precision not only of the engagement portions for optical fibers for fixing the arranged optical fibers but also of the side or bottom face used as reference faces for alignment.
Glass, ceramic, silicon, resin, etc. are used as a material constituting a member for fixing optical fibers (hereinafter referred to as “optical fiber fixing member”) such as optical fiber array or the like. Ultraviolet ray setting type adhesives having good property for work are desirable for fixing the fiber fixing lid on the optical fiber guide block and for connecting the optical fiber array with other optical fiber array or the like. Therefore, glasses having good ultraviolet transparency are getting favored as a material for optical fiber arrays. An optical fiber guide block required to have a high precision in size at optical fiber engagement portions, among optical fiber fixing members, has been fabricated by mechanically processing a glass block and the like in use of a dicing saw, diamond hone, etc. Such a fabrication process, however, raises a problem about mass production, production costs, and yields.
A method applying a method for molding optical glass lens has been known as a mass production method for optical
Fukazaki Reikou
Uno Ken
Yamashita Teruo
Yokoo Yoshiatsu
Yoshida Masahiro
Burns Doane Swecker & Mathis L.L.P.
Colaianni Michael
Hoya Corporation
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