Browse Prior Art Database

Plastic Optical Subassemblies and their Fabrication

IP.com Disclosure Number: IPCOM000118739D
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 6 page(s) / 243K

Publishing Venue

IBM

Related People

Cohen, MS: AUTHOR [+3]

Abstract

Disclosed is a method and apparatus for an optical subassembly that requires relaxed mechanical tolerances, greater flexibility in material selection and alignment along all three axes to achieve an inexpensive but nonetheless functional and durable assembly. It provides X, Y and Z axis alignment in the manufacture of an optical subassembly that achieves acceptable feedback-induced noise along with acceptable coupling efficiency.

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Plastic Optical Subassemblies and their Fabrication

      Disclosed is a method and apparatus for an optical subassembly
that requires relaxed mechanical tolerances, greater flexibility in
material selection and alignment along all three axes to achieve an
inexpensive but nonetheless functional and durable assembly.  It
provides X, Y and Z axis alignment in the manufacture of an optical
subassembly that achieves acceptable feedback-induced noise along
with acceptable coupling efficiency.

      According to the invention, there is provided a process of
aligning and fixing in place a packaged solid-state optoelectronic
converter, such as a photodetector or laser, with a housing.  The
housing has a lens firmly mounted therein and is adapted to position
a ferrule-held optical fiber.  In the practice of the process of the
invention, an oversized region of the housing is provided within
which a portion of the outside of the packaged solid-state
optoelectronic converter fits.  The range of motion of the packaged
solid-state optoelectronic converter, in two directions perpendicular
to the common  optical axis and in one direction parallel to the
common optical axis,  is limited, each direction of motion being
limited to approximately +0.2mm.  The fiber face of the optical fiber
of the ferrule-held optical  fiber is arranged in a ferrule-accepting
bore of the housing.  A position  fixing adhesive is applied while in
its compliant state in the space between the portion of the outside
of the packaged solid-state optoelectronic converter and the
oversized region of said housing. The  packaged solid-state
optoelectronic converter is moved within the oversized region,
according to an optimization prescription, while monitoring the power
level of the optical signal.  The movement experienced by said
packaged solid state optoelectronic converter is in  two directions
perpendicular to the common optical axis and in the direction
parallel to the common optical axis.

      In the transferring of optical signals between an optical fiber
and an optoelectronic converter, highly precise Optical SubAssemblies
(OSAs) are employed to hold the end of the optical fiber in alignment
with the optoelectronic converter in such a way that an acceptable
power transfer takes place.  The optoelectronic converter is a
semiconductor device.  It converts between light and electrical
signals.  The optoelectronic converter may be selected to favor a
particular direction such as transmission by using a light power
projecting laser and it may be selected to favor reception by using a
sensitive light responsive diode.  Such subassemblies are referred to
as Transmitting Optical Subassemblies (TOSAs) and Receiving Optical
Subassemblies (ROSAs), respectively.

      Fig. 1 shows a cross-sectional view of the fiber optic plastic
optoelectronic converter subassembly of the invention, showing a
fiber mounted in a ferrule which in turn is inserted into the
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