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Claims  |
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There is claimed:
1. Multichannel optical connection process, in particular for optical
fibers, comprising the following steps:
making a multichannel optical connection wafer having a plurality of
optical outlets disposed on a common face in a predetermined configuration
and with a precise pitch,
disposing said connection wafer on a support having mechanical positioning
means,
placing an assembly comprising said connection wafer and said support
facing a reference termination comprising a reference base having
mechanical positioning means adapted to cooperate with those of said
support to define a unique relative position between them and a
multichannel optical connection reference plate fixed rigidly to said base
and having on a common face at least two optical outlets disposed in the
same predetermined configuration as said connecting wafer,
dynamically aligning two outlets of said connection wafer with respective
outlets of said connection plate by three independent relative movements
between said connection wafer and the associated support, and
fixing said connection wafer to said support when said alignment is
obtained.
2. Process according to claim 1 further comprising the step of making a
second assembly comprising a multichannel optical connection wafer and a
support comprising mechanical positioning means by means of the steps of
claim 1 and a step of joining together the two assemblies so obtained by
means of their respective mechanical positioning means.
3. Process according to claim 1 consisting in assembling together two
assemblies receiving respective optical fibers.
4. Process according to claim 1 consisting connecting an assembly receiving
optical fibers to an assembly having a substrate having optical
waveguides.
5. Process according to claim 1 consisting in connecting two assemblies
having fibers or optical waveguides to an intermediate assembly.
6. Process according to claim 1 wherein said reference termination is a
universal termination used to align successive connection wafers of
different assemblies.
7. Process according to claim 1 wherein said reference termination is a
connection assembly comprising a connection wafer and a support.
8. Process according to claim 1 wherein said connection wafer and said
reference base of said reference termination constitute a single member.
9. Process according to claim 1 wherein said predetermined configuration of
said optical outlets of said connection wafer corresponds to a coplanar
disposition of the axes of said outlets.
10. Process according to claim 1 wherein said two aligned outlets of said
connection wafer comprise an outlet disposed substantially in a plane of
symmetry of said predetermined configuration and a second outlet that is
not in said plane of symmetry.
11. Process according to claim 1 wherein said three independent relative
displacements between said connection wafer and the associated support
consists in microdisplacements along two mutually orthogonal axes
orthogonal to the axis of said optical waveguides followed by rotation
about an axis substantially coincident with a central optical waveguide of
said predetermined configuration.
12. Process according to claim 1 comprising the steps of fabricating a
multichannel optical connection wafer by steps consisting in:
placing parallel ferrules on a reference surface,
positioning said ferrules by means of a member having V-grooves, and
molding a thermoplastics material over the positioned ferrules.
13. Process according to claim 12 further comprising the step of placing a
locating member opposite the ends of said ferrules, which locating member
has cones engaged in the ends of said ferrules, before carrying out said
molding step.
14. Process according to claim 12 further comprising the step of cutting
the end of said ferrules emerging from the molded part.
15. Process according to claim 1 further comprising the step of machining
the common face of two connection wafers on to which said optical outlets
open in a plane inclined to a plane normal to the axes of said optical
outlets provided in said connection wafers.
16. Process according to claim 15 wherein the machining operation is
carried out on two opposite faces of said connecting wafer.
17. Process according to claim 1 further consisting in placing an index
matching product between two assemblies each comprising a connection wafer
and a support before joining them together.
18. Process according to claim 1 further consisting in placing a protective
body around two assemblies each comprising a connection wafer and a
support when joined together.
19. Reference termination for implementing the process according to claim 1
comprising a reference base having mechanical positioning means adapted to
cooperate with those of a support to define a unique relative position
between said reference base and said support and a multichannel optical
connection reference plate fixed rigidly to said base and having on a
common face at least two optical outlets disposed in the same
predetermined configuration as a connection wafer.
20. Termination according to claim 19 wherein said reference termination
and said reference plate are combined in a single member.
21. Multichannel optical connection process, in particular for optical
fibers, comprising the following steps:
making a multichannel optical connection wafer having a plurality of
optical outlets disposed on a common face in a predetermined configuration
and with a precise pitch,
disposing said connection wafer on a support having mechanical positioning
means,
placing an assembly comprising said connection wafer and said support
facing a reference termination comprising a reference base having
mechanical positioning means adapted to cooperate with those of said
support to define a unique relative position between them and a
multichannel optical connection reference plate fixed rigidly to said base
and having on a common face at least two optical outlets disposed in the
same predetermined configuration as said connecting wafer,
dynamically aligning two outlets of said connection wafer with respective
outlets of said connection plate by three independent relative movements
between said connection wafer and the associated support, and
fixing said connection wafer to said support when said alignment is
obtained wherein said mechanical positioning means comprise a precision
cylindrical peg on said support or said reference base and a V-groove on
said reference base or said support, respectively.
22. Process according to claim 21 wherein said mechanical positioning means
further comprise a precision cylindrical peg on said support or said
reference base and a bearing plane on said reference base or said support,
respectively.
23. Process according to claim 21 wherein two cylindrical pegs are on said
support or on said reference base and said bearing plane is on said
reference base or on said support, respectively.
24. Process according to claim 21 wherein two cylindrical pegs are on said
support or on said reference base and said V-groove is on said reference
base or said support, respectively.
25. Process according to claim 21 wherein a plane of symmetry of said
predetermined configuration is substantially coincident with a plane of
symmetry of said V-groove and/or of the associated cylindrical peg.
26. Multichannel optical connection process, in particular for optical
fibers, comprising the following steps:
making a multichannel optical connection wafer having a plurality of
optical outlets disposed on a common face in a predetermined configuration
and with a precise pitch,
disposing said connection wafer on a support having mechanical positioning
means,
placing an assembly comprising said connection wafer and said support
facing a reference termination comprising a reference base having
mechanical positioning means adapted to cooperate with those of said
support to define a unique relative position between them and a
multichannel optical connection reference plate fixed rigidly to said base
and having on a common face at least two optical outlets disposed in the
same predetermined configuration as said connecting wafer,
dynamically aligning two outlets of said connection wafer with respective
outlets of said connection plate by three independent relative movements
between said connection wafer and the associated support, and
fixing said connection wafer to said support when said alignment is
obtained wherein said mechanical positioning means further comprise a
precision cylindrical peg on said support or said reference base and a
bearing plane on said reference base or said support, respectively.
27. Process according to claim 26 wherein said mechanical positioning means
comprise a precision cylindrical peg on said support or said reference
base and a V-groove on said reference base or said support, respectively.
28. Process according to claim 27 wherein two cylindrical pegs are on said
support or on said reference base and said V-groove is on said reference
base or said support, respectively.
29. Process according to claim 27 wherein a plane of symmetry of said
predetermined configuration is substantially coincident with a plane of
symmetry of said V-groove and/or of the associated cylindrical peg.
30. Process according to claim 26 wherein two cylindrical pegs are on said
support or on said reference base and said bearing plane is on said
reference base or on said support, respectively.
31. Multichannel optical connection process, in particular for optical
fibers, comprising the following steps:
making a multichannel optical connection wafer having a plurality of
optical outlets disposed on a common face in a predetermined configuration
and with a precise pitch,
disposing said connection wafer on a support having mechanical positioning
means,
placing an assembly comprising said connection wafer and said support
facing a reference termination comprising a reference base having
mechanical positioning means adapted to cooperate with those of said
support to define a unique relative position between them and a
multichannel optical connection reference plate fixed rigidly to said base
and having on a common face at least two optical outlets disposed in the
same predetermined configuration as said connecting wafer,
dynamically aligning two outlets of said connection wafer with respective
outlets of said connection plate by three independent relative movements
between said connection wafer and the associated support
fixing said connection wafer to said support when said alignment is
obtained, and
joining together two assemblies each comprising a connection wafer and a
support by means of a leaf spring holding the respective mechanical
positioning means of said two assemblies in interengagement. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns fiber communication systems.
To be more precise, the present invention relates to the field of
multichannel optical connection means designed to connect a plurality of
optical fibers simultaneously to a planar optical component or to connect
a plurality of optical fibers of one cable to a plurality of optical
fibers of another cable.
2. Description of the Prior Art
Until now optical fibers have mainly been used in long distance
transmission systems, trunk networks and interexchange networks.
From now on, however, optical fibers will be increasingly used in
distribution networks with fiber terminations in distribution chambers in
buildings and eventually in the home.
As the number of customers concerned increases, the overall economics of
the network become of vital importance.
Two contrasting scenarios using two types of architecture are emerging for
the design of these networks.
In accordance with the first scenario a single down channel serves multiple
users by means of multiplexers, couplers, and splitters.
The cost of the sender component and the fiber is therefore shared between
the users so served.
In accordance with the second scenario, there is one fiber per user but the
send and receive components are treated collectively. This simplifies
network management and there is a saving in terms of the integration
factor of the component strips used.
These contrasting options necessarily entail:
coupling of send and receive components to couplers and to splitters and
then to the fibers themselves, and
coupling of the send component strips to guides and then to the fibers.
Although these functions are at present implemented by assembling discrete
components, the cost of the latter, the lengths of intermediate fiber
used, the connectors required and the associated space requirements soon
make these uncompetitive in comparison with the planar optics technique
and its associated functions usually called OEIC.
The well-known principle of planar optics consists in forming optical
waveguides of appropriate geometry on plane substrates which can be made
from glass, silicon, silica, lithium niobate or even polymer materials,
for example.
As indicated in the article "Status of glass and silicon-based technologies
for passive components, Martin Mac Court IOOC 93", there are currently
three techniques for aligning an optical fiber with the axis of an optical
waveguide or of a second fiber and maintaining their relative positioning
after alignment.
The first technique is a dynamic alignment technique of optimizing the
power transmitted from the fiber to the guide or from fiber to fiber, and
then gluing the fiber and the guide (or the other fiber) together.
The second technique is a static alignment technique of etching very high
precision V-grooves on a substrate.
The third technique is a semi-static alignment technique of bonding fibers
into highly accurate V-grooves and micropositioning of the resulting
structures in line with a substrate.
These solutions are not entirely satisfactory, however.
The first solution is time-consuming and the time taken is proportional to
the number of outlet fibers to be aligned.
The formation of high-precision V-grooves in a substrate, as required for
the second and third solutions, is a costly high-technology operation.
The techniques used until now, as outlined above, have the further major
disadvantages of not allowing disconnection of the fibers, of poor
stability, and of not easily achieving low levels of reflection at the
component.
An object of the present invention is to improve multichannel optical
connection devices for optical fibers.
To be more precise, subsidiary objects of the invention are:
to reduce connection costs compared to the prior art,
to allow disconnection of the optical fibers,
to enable gluing on site,
to achieve low levels of reflection, and
to achieve better stability than existing products.
SUMMARY OF THE INVENTION
The invention consists in a multichannel optical connection process, in
particular for optical fibers, comprising the following steps:
making a multichannel optical connection wafer having a plurality of
optical outlets disposed on a common face in a predetermined configuration
and with a precise pitch,
disposing said connection wafer on a support having mechanical positioning
means,
placing the assembly comprising said connection wafer and said support
facing a complementary reference termination comprising a reference face
having mechanical positioning means adapted to cooperate with those of
said support to define a unique relative position between them and a
multichannel optical connection reference plate fixed rigidly to said base
and having on a common face at least two optical outlets disposed in the
same predetermined configuration as said connecting wafer,
dynamically aligning two outlets of said connection wafer with respective
outlets of said connection plate by three independent relative movements
between said connection wafer and the associated support, and
fixing said connection wafer to said support when said alignment is
obtained.
To connect a multiple optical fiber cable to an associated system, second
multiple optical fiber cable or planar optical component, it is sufficient
to equip said cable and said associated system with an assembly of this
kind comprising a multichannel optical connection wafer and a support with
accurately defined relative positions and to assemble these two assemblies
together using their respective mechanical positioning means.
In the context of the invention, the reference termination can be a
universal (i.e. general purpose) termination if it is potentially
necessary to connect the connection wafer/support assembly to a plurality
complementary assemblies. In this case, said complementary assemblies are
themselves constituted from the same universal reference termination.
Alternatively, the reference termination can be constituted by an assembly
comprising a connection wafer and a support fixed together beforehand in
an arbitrary manner if there is no requirement for the connection to be
universal.
In accordance with one advantageous feature of the invention said
predetermined configuration of said optical outlets of said connection
wafer corresponds to a coplanar disposition of the axes of said outlets.
In accordance with another advantageous feature of the invention the
complementary mechanical positioning means comprise a precision
cylindrical peg on said support of said reference bases and a V-groove on
said reference base or said support, respectively.
In accordance with another advantageous feature of the invention the
complementary mechanical positioning means further comprise a precision
cylindrical peg on said support or said reference base and a bearing plane
on said reference base or said support, respectively.
In accordance with another advantageous feature of the invention the two
cylindrical pegs are on said support or on said reference base and said
V-groove and said bearing plane are on said reference base or said
support, respectively.
In accordance with another advantageous feature of the invention the two
aligned outlets of said positioning wafer comprise an outlet disposed
substantially in the plane of symmetry of said predetermined configuration
and a second outlet that is not in said plane of symmetry.
In accordance with another advantageous feature of the invention the plane
of symmetry of said predetermined configuration is substantially
coincident with the plane of symmetry of said V-groove and/or of the
associated cylindrical peg.
Other features, objects and advantages of the present invention will emerge
from a reading of the following detailed description given by way of
non-limiting example with reference to the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic perspective view of two assemblies of a
multichannel optical connection system in accordance with the present
invention, before they are joined together.
FIG. 2 is an end-on lateral view of one of these assemblies.
FIG. 3 shows part of this same assembly in longitudinal section.
FIG. 4 shows an intermediate step in the fabrication of one of the
connection assemblies.
FIG. 5 is an end-on view of the component shown in FIG. 4 during the same
fabrication step.
FIGS. 6 and 7 are diagrammatic perspective views of two reference
terminations used in the context of the present invention.
FIG. 8 shows an alternative embodiment of a support in accordance with the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The appended FIG. 1 shows a connection system in accordance with the
present invention comprising a connector assembly 100 adapted to receive a
plurality of optical fibers and an assembly 200 comprising a substrate 210
with a corresponding number of optical waveguides 220.
Each of the assemblies 100 and 200 comprises a wafer 110, 210 on a support
150, 250.
The wafers 110, 210 each have a plurality of optical outputs 122, 222
disposed on a common face 112, 212 of the wafers 110, 210 in a
predetermined configuration and with a precise pitch p. To be more
precise, in the preferred embodiment of the invention shown in the
appended figures said predetermined configuration of the optical outputs
122, 222 corresponds to a coplanar disposition of the axes of said
outputs. Also, the pitch p of the optical outputs 122, 222 is identical on
both wafers 110, 210 forming the respective assemblies 100, 200.
The supports 150, 250 comprise respective complementary mechanical
positioning means 152, 155 and 252, 255 described in detail below and
adapted to define a unique relative position of the two supports 150 and
250.
There is next described the preferred process for fabricating the connector
assembly 100 adapted to receive a plurality of optical fibers. The first
step is to make the plane and generally parallelepipedal wafer 110
comprising ferrules 120 with coplanar parallel axes.
The ferrules 120 have an outside diameter D less than the pitch p of the
optical outputs and an inside diameter d to suit the outside diameter of
the optical fibers they are to receive, typically in the order of 126
.mu.m.
The person skilled in the art knows how to make accurate ferrules for
receiving optical fibers, in particular using known fiber drawing
techniques. The process of fabricating such ferrules 120 is not described
hereinafter for this reason. In particular, the person skilled in the art
knows how to make silica ferrules whose outside diameter D, inside
diameter d and eccentricity between the inside diameter d and the outside
diameter D are defined to an accuracy of 1 micron.
Referring to FIG. 3, the internal passage 121 of each ferrule 120
preferably has a conical end 123 to facilitate insertion of the optical
fibers into said ferrules.
Referring to FIGS. 4 and 5, to make a wafer 110 with n channels adapted to
receive the fibers in a common plane and at a precise pitch p, n ferrules
120 are placed on a plane reference surface 502 formed on a member 500.
To be more precise, the n ferrules 120 are pressed onto the reference
surface 502 by a high-precision wafer 510 having V-grooves 512 of very
precise depth and pitch p.
The wafer 510 can be of the type used in the conventional prior art
processes, for example an etched silicon wafer. An etched silicon wafer
510 is undoubtedly costly. However, in the context of the invention, the
wafer 510 is used only to position the ferrules 120. It is not an integral
part of the connection assembly and consequently can be used an unlimited
number of times.
At the end of the ferrules 120, to be more precise facing their conical
ends 123 is a locating member 520 carrying cones 522 at the same pitch p
as the grooves 512 in the wafer 510. The cones 522 engage in the conical
ends 123 of the ferrules 120 and have the same cone angle as the latter.
The cones 522 therefore block off the entries 123 of the ferrules 120.
The reference plate 500 has two lateral walls 530, 532. After placing the
ferrules 120, the grooved wafer 510 and the chock 520 as described, the
ferrules 120 are embedded in a molding resin cast in the space between the
grooved wafer 510, the locating member 520 and the walls 530, 532.
This molding operation produces the wafer 110. After it, the ends of the
ferrules 120 which project from the wafer 110 are sawn off in a plane 514
(FIG. 4) at which the molded wafer 110 and the grooved component 510 meet.
This yields a thermoplastic material wafer 110 containing the ferrules 120
with parallel and coplanar axes 124. The ferrules 120 are disposed in
passages 125 which respectively open onto the aforementioned face 112 of
the wafer 110 and onto its opposite face 114.
To be more precise, the conical ends 123 of the ferrules 120 open into
pre-centering cones 115 formed by the cones 522 and which themselves open
onto the outside face 114 of the wafer 110. The opposite ends of the
ferrules 120 are flush with the outside surface 112 of the wafer 110.
The resulting wafer 110 is placed on a support 150. The support 150 is
preferably a rectangular parallelepiped. The support 150 has two plane
parallel main faces 156, 157.
The wafer 110 is disposed on the first face 156 of the support 150.
The support 150 has mechanical positioning means on its second face 157.
To be more precise, the support 150 preferably has a V-groove 152 on its
face 157. The V-groove 152 is preferably in a plane of symmetry 153 of the
support 150 orthogonal to the aforementioned faces 156, 157.
The support 150 has on the same face 157 a rebate 154 adjacent one lateral
face 158 of the support. The rebate 154 defines a plane bearing surface
155 parallel to the main faces 156 and 157 of the support 150 and which
opens onto its lateral surface 158.
In the context of the invention, there are no particular dimensional
accuracy requirements with regard to the groove 152 or the rebate 154.
They are merely required to be flat.
The support 150 preferably has a rebate 162 adjacent to its lower surface
157 on its transverse face 160 orthogonal to the previously mentioned main
faces 156, 157 and lateral face 158 and which coincides with the
aforementioned face 112 of the wafer 110. The purpose of the rebate 162 is
to facilitate inclined polishing of the face 112 of the wafer 110 and of
the corresponding face 160 of the support 150 and the ends of the ferrules
120 (see below).
The resulting assembly comprising the wafer 110 disposed on the support 150
is then placed on a reference termination 300 of the type shown in FIG. 6.
This reference termination 300 includes a reference plate 310 and a
reference base 350.
The reference plate 310 comprises two optical waveguides 320, 321. The
optical waveguides 320, 321 can be optical fibers, possibly optical fibers
in ferrules similar to the ferrules 120; they can instead be fabricated
using planar optics technology.
The optical waveguides 320, 321 have their outlet on a common face 312 of
the reference plate 310. These outlets correspond to the predetermined
configuration of the ferrules 120 in the wafer 110.
The reference base 350 comprises mechanical positioning means complementary
to the groove 152 and the bearing surface 155 on the support 150.
In the preferred embodiment of the invention shown in FIG. 6 the mechanical
positioning means of the reference base 350 comprise two precision
cylindrical pegs 352, 355. The two pegs 352, 355 preferably have parallel
axes. They project from a transverse lateral face 360 of the support base
350. The pegs 352, 355 preferably have the same diameter.
The axes of the pegs 352, 355 are parallel to the main faces 356, 357 of
the support base 350 and orthogonal to its transverse face 360.
One of the reference optical waveguides 320 is preferably in a plane of
symmetry of the base 350 perpendicular to the aforementioned faces 356,
357 and 360 of the base 350. This plane of symmetry preferably coincides
with the axis 353 of the peg 352.
The optical waveguide 321 is preferably the outermost waveguide in the
predetermined configuration adopted.
The axes of the outlets of the optical waveguides 320, 321 are in a plane
parallel to the plane passing through the axes of the pegs 352, 355.
Finally, the distance between the axes of the outlets of the optical
waveguide 300, 321 is preferably equal to the distance between the axes of
the pegs 352, 355. In other words, the optical waveguides 320, 321 are
vertically aligned with the respective pegs 352, 355 and the distance
between the axis of the waveguide 320 and the peg 352 is equal to the
distance between the axis of the waveguide 321 and the peg 355.
Accordingly, the distance between the axes of the two optical waveguides
321 is a multiple of the pitch p of the configuration adopted.
As shown in FIG. 6, the reference plate 310 is fixed to the reference
support base 350 by means of a layer of glue 390 or alternatively by
welding or any equivalent technique.
As an alternative to this, the reference plate 310 and the reference
support base 350 can be made in one piece.
In the assembly 100 the depth of the V-groove 152 and of the rebate 154 are
preferably such that when the assembly 100 is resting on the reference
termination 300 the plane passing through the axes of the ferrules 120 is
parallel to the plane containing the axes of the pegs 352, 355 and
coincides with the plane passing through the axes of the reference optical
waveguides 320, 321.
After positioning the wafer 110 on the support 150 in this way, respecting
the symmetry of the ferrules 120 relative to the groove 152, the wafer
110/support 150 assembly is placed on the reference termination 300.
Because of the cooperation defined between the pegs 352, 355 and the
groove 152 and the bearing surface 355, respectively, the support 150 is
located in a unique position relative to the reference support base 350
and therefore relative to the reference plate 310 which is attached to it.
The positioning of the central ferrule 120 on the central reference optical
waveguide 320 is optimized by microdisplacements between the wafer 110 and
the support 150 in x and y directions, controlled (for example) by
monitoring the transmitted flux. By "microdisplacement in x and y
directions" is-meant a relative displacement between the wafer 110 and the
support 150 in two directions orthogonal to each other and orthogonal to
the axes of the pegs 352, 355, the x direction being parallel to the main
faces 156, 157 of the support and the y direction being orthogonal to
these main faces 156, 157 (see FIG. 2).
By "monitoring the transmitted flux" is meant monitoring of the power of
the flux transmitted between the central ferrule 120 and the optical
waveguide 320 during this microdisplacement.
Again by monitoring the transmitted flux, for example, relative rotation
between the plate 110 and the support 150 about an axis substantially
coincident with the central optical waveguide 320 in the direction of the
arrow .theta. (see FIG. 2) aligns the outside ferrule 120 with the outside
reference guide 320.
When these operations have been completed, the ferrules 120 occupy the same
position relative to the mechanical positioning means 152, 155 as the
reference waveguides 320, 321 of the reference termination occupy relative
to the pegs 352, 355.
The relative positions of the wafer 110 and the support 150 are then fixed
by any appropriate conventional means, for example by welding or by means
of a layer of glue 190 between the wafer 110 and the support 150.
The pre-alignment of the central ferrule 120 guarantees a symmetrical
distribution of displacements due to dimensional variations associated
with thermal effects and therefore a minimal error relative to the
optimized initial position.
The assembly 100 previously described is then ready for use.
The assembly 200 including the substrate 210 is prepared in a similar
manner.
The substrate 210 is in the form of a plane wafer with optical waveguides
220 whose outlets 222 are on a common face 212 with the same predetermined
configuration and the same precise pitch p as the ferrules 120 on the
wafer 110. Integrated optical technologies which usually employ
photolithography and masking techniques can now fabricate the optical
waveguides 220 at an extremely accurate pitch (to within better than 0.5
.mu.m). The depth of the optical waveguides 220, usually formed by
diffusion, deposition or selective etching, also yields an accuracy to
within one micron.
In a similar way to the assembly 100, the assembly 200 is positioned on a
support 250. The substrate 210 can be fixed direct to the support 250.
However, the substrate 210 is preferably fixed first to an intermediate
support member 270. This intermediate support member 270 is needed to
compensate for the fact that the height of the substrates 210 can differ
markedly from one substrate to another, depending on the technologies
used. This intermediate member 270 preferably has an L-shape
cross-section. The intermediate member 270 comprises two orthogonal
branches 272, 274. The longer branch 272 supports the outside surface 273
of the substrate 210. The inside surface 275 of the shorter branch 274
constitutes a reference surface perpendicular to the axes of the optical
waveguides 220 and provides an abutment for the support 250.
The substrate 210 can be fixed to the intermediate support 270 by any
appropriate conventional means.
Like the reference base 350 of the termination 300 previously described,
the support 250 has mechanical positioning means adapted to cooperate with
the V-groove 152 and the bearing surface 155 of the assembly 100.
Accordingly, the support 250, which is a rectangular parallelepiped,
comprises two precision pegs 252, 255 projecting from its transverse face
260.
The pegs 252, 255 can be identical as to their geometry, dimensions and
relative disposition to the aforementioned pegs 352, 355. For this reason
the pegs 252, 255 are not described in more detail below.
The assembly 200 comprising the wafer 210 disposed on the support 250 and
the intermediate support 270 is then placed on a complementary reference
termination 400 of the type shown in FIG. 7.
The reference termination 400 comprises a reference plate 410 and a
reference support base 450.
The reference plate 410 comprises two reference optical waveguides 420, 421
homologous to the respective optical waveguides 320, 321 on the reference
termination 300. In other words, the predetermined configuration of the
optical waveguides 420, 421 is the same as the predetermined configuration
of the waveguides 320, 321.
The support base 450 comprises mechanical positioning means 452, 454, 455
complementary to the pegs 252, 255 on the support 250. The mechanical
positioning means 452, 454, 455 are identical to the groove 152, the
rebate 154 and the bearing surface 155 on the support 150.
Accordingly, the support 450 comprises a V-groove 452 and a rebate 454
delimiting a bearing surface 455 which opens onto its lower surface 457.
The optical waveguide 420 and the groove 452 are preferably in the plane
of symmetry 453 of the termination 400.
The wafer 410 is fixed to the upper surface 456 of the support base 450 by
any appropriate means, for example by soldering or by means of a layer of
glue 490.
The positioning of the guides 420, 421 relative to the mechanical
positioning means 452, 455 is such that when the reference termination 400
is placed on the pegs 352, 355 of the reference termination 300 the
optical waveguides 420, 421 are respectively aligned with the optical
waveguides 320, 321.
After thus placing the reference termination 400 on the pegs 252, 255 of
the support 250 of the assembly 200, the substrate 210 is adjusted by
microdisplacement in the x and y directions relative to the support 250,
controlled (for example) by monitoring the transmitted flux, to align the
central optical waveguide 220 with the central reference optical waveguide
420. Then rotation of the substrate 210 relative to the support 250 about
an axis substantially coincident with that of the central reference
waveguide 420 aligns the external optical waveguide 220 with the reference
optical waveguide 421.
Once these operations have been completed the optical waveguides 220 on the
substrate 210 occupy the same position relative to the pegs 252, 255 as
the reference waveguides 420, 421 relative to the groove 452 and the
bearing surface 455.
The substrate 210 and the support 250 are then fixed in this optimized
position by welding or by means of a layer of glue 290 between the
intermediate support 270 and the support 250.
In the implementation as previously described, the two assemblies 100 and
200 are each positioned relative to complementary universal reference
terminations 300, 400. Accordingly, for both assemblies 100 and 200, the
ferrules 120 and optical waveguides 220 occupy a precise universal
position relative to the respective mechanical positioning means 152, 155
and 252, 255.
Both assemblies 100 and 200 are therefore universal assemblies and can be
combined or mixed and matched by family.
The accuracy of the alignment of the waveguides 220 and the fibers in the
ferrules 120 is guaranteed by a non-trivial optimization operation which
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