Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
1999-10-20
2001-05-29
Kim, Robert H. (Department: 2877)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
C385S089000
Reexamination Certificate
active
06238100
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an optical module to be connected with an optical fiber connector used in an optical communication and a method for fabricating the same.
BACKGROUND OF THE INVENTION
In an optical transmission apparatus which is provided with a great number of laser diode, photo-detector or semiconductor optical amplifier array modules and transmits or receives optical signals via optical fiber arrays, disposal of excess pigtails of optical modules mounted on a board is important. Especially, in the transmission apparatus for processing the high bit rate optical signals of several Gb/s, it is necessary to control the lengths of the optical fibers in the order of cm. Two ways can be devised for controlling the lengths of the optical fibers. In the first way, the lengths of the respective pigtails are separately controlled internally in the optical module. In the second way, an optical fiber connector supporting the external optical fibers, the lengths of which are respectively controlled, is fabricated, and the optical module is connected with and removed from the aforementioned optical fiber connector. In the second way, the lengths of the optical fibers can be more easily controlled than in the first way, and the space on the board can be saved.
On the optical module to be connected with the optical fiber connector designed for a multi-mode optical fiber array in which tolerance limits of misalignments of optical axes of the optical fibers are comparatively loose, many developments of optical parallel interconnection modules have been reported. However, with the further expansion of the transmission capacity and the extension of the transmission distance expected in future, the realization of the optical module to be connected with the single mode optical fibers is expected.
Moreover, in order to realize miniaturization of the optical module having the function of an optical switching and a wavelength selecting in the multi-channel optical transmission system, a hybrid integrated structure in which an optical device is integrated with an optical waveguide device, such as a planar optical circuit, is desired. In the aforementioned structure, it becomes necessary to connect the optical waveguides with the single mode optical fiber array with high effeciency.
Hitherto, as means for connecting the optical waveguides with the optical fiber array which lies between the optical waveguides and the optical fiber connector, the structure shown in
FIGS. 1A and 1B
is known (M. Takaya, et. al., Technical Digest Integrated Photonics Research, IWH2, 1996)
As shown in
FIG. 1A
, an optical module
110
is fabricated by sticking a plug component
111
and an optical waveguide chip
112
together. In the optical waveguide chip
112
, plural optical waveguides
113
are formed in parallel each other. On the inner surfaces of the plug component
111
and the optical waveguide chip
112
, V grooves
111
a
and
112
a
are respectively formed, and a positioning of the plug component
111
relative to the optical waveguide chip
112
is performed by inserting pins
114
into the V grooves
111
a
and
112
a.
Near both the side ends of the plug component
111
, guide holes
115
for positioning the plug component
111
relative to the optical fiber connector
120
shown in
FIG. 1B
are formed. As shown in
FIG. 1B
, plural optical fibers
121
running in parallel with each other are buried in the optical fiber connector
120
, and guide holes
122
for positioning the optical fiber connector
120
relative to the optical module
110
are formed near both the side ends of the optical fiber connector
120
.
Positioning of the optical fiber connector
120
relative to the optical module
110
are performed by inserting guide pins (not shown) into the guide holes
122
and
115
, and thereby the optical waveguides
113
of the optical module
110
are connected with the optical fibers
121
of the optical fiber connector
120
.
In the structure for connecting the optical fibers
121
with the optical module
110
by means of the optical fiber connector
120
, it is very important that end faces of the optical fibers
121
and the optical guide
113
are flattened. Accordingly, both the end faces are specularly polished.
However, in the aforementioned conventional optical module, it is necessary to stick the waveguide chip and the plug component together with high accuracy in order to specularly polish the end face of the optical waveguide, but the aforementioned sticking process is very difficult. The reason is that, although positionings of the optical waveguides in the horizontal and vertical directions are successfully performed because of the existence of the pins, the aforementioned structure has no means for positionings the optical waveguides in the direction of the optical axes thereof.
Moreover, a heavy load is applied to the optical module in case that the optical fiber connector is connected with or removed from the optical module. However, since the optical module is formed by sticking the optical waveguide chip and the plug component together with adhesion, the optical module cannot withstand the aforementioned load applied thereto.
As a method for increasing the strength of the optical module, a following one can be devised. That is to say, the optical waveguides are sandwiched by two parallel reinforcing plates near the end face of the optical waveguides, which are opposed to the fiber block (the optical fiber array) face to face. Then, the position of the fiber block relative to the optical waveguides is optimized by monitoring intensities of lights emitted from the fiber block, and the are stuck together. However, according to this method, since complicated works for aligning to the optical axes are added, it is undesirable from viewpoints of an increasing in cost and low productivity.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an optical module which withstands a force applied thereto in case that an external optical fiber connector is connected with an removed from an optical module and makes optical adjustments for aligning optical axes unnecessary.
It is a further object of the invention to provide a method for fabricating an optical module which withstands a force applied thereto in case that an external optical fiber connector is connected with and removed from an optical module and makes optical adjustments for aligning optical axes unnecessary.
According to the first feature of the invention, an optical module to be connected with an removed from an external optical fiber connector supporting plural parallel optical fibers for an optical signal transmission (optical fibers for transmission, hereinafter), comprises:
a substrate on which an optical device is mounted,
a basic member on which the substrate is mounted,
a block which fits to the basic member at a side end thereof, partially projects plural parallel internal optical fibers (optical fibers, hereinafter) to be connected with the optical device at a first end face of the block, and support remainders of the internal optical fibers so that end faces of the remainders are exposed at a second end face of the block, and
plural parallel V grooves (V grooves, hereinafter) which have end walls, are formed on the substrate and supports the respective internal optical fibers projected from the block,
wherein a lateral pitch of the V grooves are a same as that of the optical fibers.
In the optical module according to the invention, the plural optical fibers are supported by a block, which is fitted to the basic member. The optical fibers projected from the first end face of the block are supported by the V grooves, which are respectively formed on the substrate. The position of the optical fiber supported by the V groove on a horizontal axis which corresponds to the width direction of the optical fibers arranged in parallel with each other is determined by a position of the V groove. The height of the aforementioned optical fiber above the substrate
Itoh Masataka
Kato Tomoaki
Sasaki Jun-ichi
Kim Robert H.
McGinn & Gibb PLLC
NEC Corporation
Stafira Michael P.
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