U.S. patent application number 09/742179 was filed with the patent office on 2002-01-10 for fiber array with wick-stop trench for improved fiber positioning.
Invention is credited to Hurst, James C. JR., Sherrer, David W..
Application Number | 20020003933 09/742179 |
Document ID | / |
Family ID | 46277194 |
Filed Date | 2002-01-10 |
United States Patent
Application |
20020003933 |
Kind Code |
A1 |
Sherrer, David W. ; et
al. |
January 10, 2002 |
Fiber array with wick-stop trench for improved fiber
positioning
Abstract
A V-groove chip for fiber arrays having a wick stop trench. The
wick stop trench intersects the V-grooves and is preferably deeper
than the V-grooves. The wick stop trench prevents adhesive from
moving via capillary action along the entire length of a V-groove.
This is very useful for manufacturing V-groove fiber arrays because
often it is desirable to adhesive the fiber to the V-groove chip in
multiple gluing steps. For example, two gluing steps are beneficial
if rotational alignment of the fiber (e.g., for polarization
maintaining fiber arrays) is desired. Also, if longitudinal
alignment of the fiber is desired, two gluing steps are beneficial.
Two gluing steps allows the front and rear portions of the optical
fiber to be secured independently, thereby improving precision in
fiber placement. Preferably, the wick stop trench is filled with
solidified adhesive.
Inventors: |
Sherrer, David W.;
(Blacksburg, VA) ; Hurst, James C. JR.;
(Wytheville, VA) |
Correspondence
Address: |
Dan Steinberg
ACT MicroDevices
7586 Peppers Ferry Loop
Radford
VA
24141
US
|
Family ID: |
46277194 |
Appl. No.: |
09/742179 |
Filed: |
December 20, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09742179 |
Dec 20, 2000 |
|
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|
09526922 |
Mar 16, 2000 |
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6215946 |
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Current U.S.
Class: |
385/83 ; 385/137;
385/80 |
Current CPC
Class: |
G02B 6/3861 20130101;
G02B 6/3652 20130101; G02B 6/3812 20130101; G02B 6/3692 20130101;
G02B 6/3636 20130101; G02B 6/3839 20130101 |
Class at
Publication: |
385/83 ; 385/80;
385/137 |
International
Class: |
G02B 006/36 |
Claims
What is claimed is:
1. An optical fiber array, comprising: a) a substrate having a top
surface; b) a groove disposed in the top surface; c) a wick stop
trench intersecting the groove so that the groove is divided into
groove sections; d) an optical fiber disposed in the groove
sections and crossing the wick stop trench; e) solidified adhesive
filling the wick stop trench.
2. The optical fiber array of claim 1 wherein the solidified
adhesive has a fillet boundary.
3. The optical fiber array of claim 2 wherein the fillet boundary
extends to the bottom of the wick stop trench.
4. The optical fiber array of claim 1 wherein the wick stop trench
is deeper than the groove.
5. The optical fiber array of claim 1 wherein the substrate is made
of single crystal silicon and the groove is a crystallographically
defined V-groove.
6. The optical fiber array of claim 1 wherein the wick stop trench
has vertical sidewalls.
7. The optical fiber array of claim 1 wherein the wick stop trench
is a dicing saw cut trench.
8. The optical fiber array of claim 1 wherein the wick stop trench
has a width in the range of 20-500 microns.
9. The optical fiber array of claim 1 wherein the wick stop trench
has a width in the range of 100-200 microns.
10. The optical fiber array of claim 1 further comprising a second
wick stop trench so that the groove is divided into three groove
sections, and wherein the second wick stop trench is filled with
solidified adhesive.
11. The optical fiber array of claim 1 wherein the wick stop trench
intersects a midpoint of the groove so that the groove is divided
into two equal-length groove sections.
12. The optical fiber array of claim 1 wherein the groove sections
are at least 200 microns long.
13. The optical fiber array of claim 1 wherein the groove sections
are at least 1000 microns long.
14. The optical fiber array of claim 1 wherein the optical fiber is
a polarization maintaining optical fiber.
15. The optical fiber array of claim 1 wherein the optical fiber
has a fiber endface, and wherein the substrate has a front face,
and wherein the fiber endface is not coplanar with the substrate
front face.
16. The optical fiber array of claim 1 wherein the solidified
adhesive comprises two fillet boundaries adjacent to the front and
rear groove sections.
17. A method for making an optical fiber array, comprising the
steps of: a) providing a groove chip having a wick stop trench and
a groove, wherein the groove is divided by the trench into a front
groove section and a rear groove section; b) disposing an optical
fiber in the front and rear groove sections so that it crosses the
trench; c) applying liquid adhesive to the rear groove section so
that the liquid adhesive flows along the optical fiber up to the
wick stop trench and forms a fillet; d) curing the adhesive applied
in step (c); e) after step (d), filling the wick stop trench with
adhesive so that the liquid adhesive flows into the front groove
section; f) curing the adhesive applied in step (e)
18. The method of claim 17 wherein different adhesives are used in
steps (c) and (e).
19. The method of claim 17 further comprising the step of providing
rotational alignment of the optical fiber before step (d).
20. The method of claim 17 further comprising the step of providing
longitudinal alignment of the optical fiber before step (d).
21. An optical fiber array made according to the method of claim 17
so that the fiber array has a fillet boundary.
22. A method for making an optical fiber array, comprising the
steps of: a) providing a groove chip having a wick stop trench and
a groove divided into a front groove section, wherein the groove is
divided by the trench into a front groove section and a rear groove
section; b) disposing an optical fiber in the front and rear groove
sections so that it crosses the trench; c) applying liquid adhesive
to the rear groove section so that the liquid adhesive flows along
the optical fiber up to the wick stop trench and forms a fillet; d)
curing the adhesive applied in step (c); e) applying liquid
adhesive to the front groove section so that the liquid adhesive
flows along the optical fiber up to the wick stop trench and forms
a second fillet; f) curing the adhesive applied in step (e); g)
after step (f), filling the wick stop trench with adhesive; h)
curing the adhesive applied in step (g).
23. The method of claim 16 wherein different adhesives are used in
steps (c) and (e).
24. The method of claim 16 further comprising the step of providing
rotational alignment of the optical fiber before step (d).
25. The method of claim 16 further comprising the step of providing
longitudinal alignment of the optical fiber before step (d).
26. An optical fiber array made according to the method of claim 22
so that the fiber array has two fillet boundaries.
Description
RELATED APPLICATIONS
[0001] The present patent application is a continuation-in-part of
copending parent patent application 09/526,922, filed on Mar. 16,
2000. The present application claims the benefit of priority of the
parent application.
FIELD OF THE INVENTION
[0002] The present invention relates generally to optical fiber
arrays and micromachined chips used in optical fiber arrays. More
specifically, it relates to a V-groove chip having a wick stop
trench to prevent the uncontrolled wicking and movement of adhesive
during manufacture of a V-groove fiber array.
BACKGROUND OF THE INVENTION
[0003] Micromachined V-groove chips are commonly used in the
optical fiber industry and photonics industry to align and position
optical fibers. Typically, V-groove fiber arrays are made by
placing optical fibers in V-grooves of a V-groove chip, placing a
lid on the fibers, and then securing the assembly with adhesive.
The lid can be a V-groove chip or a flat silicon or glass plate.
The adhesive is typically a UV-curable or heat-curable epoxy.
[0004] The optical fibers must be carefully located in the
V-grooves during manufacture of the array. Specifically, the
optical fibers must be disposed in contact with the surfaces of the
V-grooves. Also, for fiber arrays having polarization-maintaining
fiber, the optical fibers must have an accurate rotational
alignment. Also, some fiber arrays need to have optical fibers
placed so that the fiber endfaces are fixed at different
longitudinal positions.
[0005] It can be difficult to position optical fibers in
conventional V-groove chips. This is because adhesive used to
secure the fibers wicks by capillary action into the small spaces
between the fibers and V-grooves. Since the adhesive wicks into
these spaces, the entire length of the fiber is secured to the
V-groove chip in a single step. It is not possible to secure the
fiber in the V-groove in multiple gluing steps. This is a problem
for certain fiber arrays because multiple gluing steps can improve
the alignment of optical fibers.
[0006] U.S. Pat. No. 5,257,332 to Pimpinella discloses a fiber
coupler having V-groove chips.
[0007] U.S. Pat. No. 5,748,822 to Miura et al. discloses a module
for connecting an optical fiber to an optical element such as a
laser diode. The module has a vertical groove cut perpendicular to
the V-grooves. The vertical groove is positioned to abut the fiber
endface and provide longitudinal positioning of the optical
fiber.
OBJECTS AND ADVANTAGES OF THE INVENTION
[0008] Accordingly, it is a primary object of the present invention
to provide a V-groove chip that:
[0009] 1) controls wicking of adhesive so that optical fibers can
be glued in multiple gluing steps;
[0010] 2) provides for improved alignment of optical fibers in a
V-groove chip;
[0011] 3) provides for improved longitudinal alignment of optical
fibers;
[0012] 4) provides for improved rotational alignment optical
fibers.
[0013] These and other objects and advantages will be apparent upon
reading the following description and accompanying drawings.
SUMMARY OF THE INVENTION
[0014] These objects and advantages are attained by a V-groove chip
having a wick stop trench. The wick stop trench intersects the
V-groove. An optical fiber is disposed in the V-groove and crosses
over the wick stop trench. The wick stop trench is filled with
adhesive. The wick stop trench prevents adhesive from moving via
capillary action along the entire length of the V-groove. This
provides increased control over adhesive application and placement
of the fiber in the V-groove. Preferably, the wick stop trench is
deeper than the V-groove.
[0015] Preferably, the wick stop trench has vertical sidewalls.
Also, the trench can be cut using a dicing saw.
[0016] The trench can have a width of about 20-500 microns or
wider. More preferably the width is in the range of 100-200
microns. The wick stop trench can even be 1-5 mm wide if
desired.
[0017] Preferably, the trench is perpendicular to the V-groove.
[0018] Also preferably, the trench divides the V-groove into groove
sections of equal length. Preferably, the groove sections are at
least 200 or 1000 microns long. Alternatively, the groove sections
can be 10, 50, or 100 microns long.
[0019] The present invention includes a method for making a fiber
array having a wick stop trench. In this method, an optical fiber
is disposed in the V-groove. The fiber is glued to front and rear
groove sections in separate gluing steps. Optionally, different
adhesives are used in gluing the front and rear groove sections.
Also, rotational or longitudinal alignment can be provided for the
fiber before the fiber is glued to the front groove section. In a
final step, the wick stop trench is filled with adhesive, and the
adhesive is cured.
DESCRIPTION OF THE FIGURES
[0020] FIG. 1 is a V-groove chip according to the present
invention.
[0021] FIG. 2 is a side view of a V-groove chip of the present
invention.
[0022] FIGS. 3a-b are side views of V-groove arrays of the present
invention.
[0023] FIGS. 4a-b illustrate a preferred method for making the
present invention.
[0024] FIGS. 5a-d illustrate a preferred method of the present
invention.
[0025] FIG. 6 is a top view illustrating longitudinal positioning
according to the present invention.
[0026] FIG. 7 is a side view of a V-groove chip having two wick
stop trenches.
[0027] FIG. 8 is a top view of an embodiment where the wick stop
trench is not perpendicular to the V-grooves.
[0028] FIG. 9 shows a side view of the present fiber array having a
filled wick stop trench.
[0029] FIGS. 10a-10b illustrate a preferred method for making the
present fiber array with a filled wick stop trench.
[0030] FIG. 11 shows a close-up side view of the wick stop trench,
illustrating a fillet boundary.
[0031] FIG. 12 shows a close-up side view of the wick stop trench,
illustrating a fillet boundary that extends to the bottom of the
wick stop trench.
[0032] FIG. 13 shows a close-up side view of a fiber array having
two fillets created by separate adhesive applications to the front
groove section and rear groove section.
[0033] FIG. 14 show a clasp side view of a fiber array with a
fillet wick stop trench and two fillet boundaries. The fiber array
of FIG. 14 is made by filling the wick stop trench of the fiber
array of FIG. 13.
DETAILED DESCRIPTION
[0034] A V-groove chip according to the present invention has a
wick stop trench that prevents adhesive from wicking the entire
length of a V-groove. The wick stop trench is perpendicular to the
V-groove and preferably deeper than the V-groove. The wick stop
trench divides the V-groove into groove sections which can be glued
separately in distinct gluing steps. The ability to secure a fiber
in multiple gluing steps facilitates improved fiber positioning.
The present invention is particularly well suited for accurate
longitudinal and rotational positioning of an optical fiber in a
V-groove.
[0035] FIG. 1 shows a V-groove chip according to a preferred
embodiment of the present invention. The V-groove chip has a
substrate 20 with a top surface 22. V-grooves 24a-f are disposed in
the substrate 20. A wick stop trench 26 intersects the V-grooves
24a-f. Groove sections 24a-b are aligned across the wick stop
trench 26 and in the present application are considered to comprise
a single V-groove. Similarly, groove sections 24c-d and 24e-f are
aligned and considered to comprise single V-grooves.
[0036] V-groove sections 24a-f are aligned in a longitudinal
direction 28, and the wick stop trench 26 is aligned in a
transverse direction 30. Preferably, the wick stop trench 26 is
perpendicular to the V-grooves 24a-f.
[0037] Also preferably, the substrate 20 is made of single crystal
silicon, and the top surface 22 is aligned with the
<100>crystal plane. V-grooves 24a-f are preferably made by
wet anisotropic orientation dependent etching (e.g. using KOH) as
is known in the art of silicon micromachining. The wick stop trench
26 is preferably made by a dicing saw, and can have a wide range of
depths and widths. The wick stop trench 26 is preferably deeper
than the V-grooves 24a-f. Alternatively, the wick stop can be made
by any other micromachining technique (e.g. reactive ion etching is
a possibility). The location and dimensions of the wick stop trench
do not need to be precisely defined.
[0038] It is noted that V-groove chips are sometimes made from
quartz or similar materials with V-grooves formed by grinding. The
present invention is equally applicable to such V-groove chips.
[0039] FIG. 2 shows a side view of the wick stop trench 26. Dotted
lines 32 indicate the bottom corners of the V-grooves 24a-f. The
wick stop trench has sidewalls 38. In some embodiments, the
sidewalls 38 are vertical (i.e. perpendicular to the top surface).
The sidewalls 38 are vertical in embodiments where the trench is
made using a dicing saw. The wick stop trench 26 has a width 34 and
a depth 36. As noted, the wick stop trench is preferably deeper
than the V-grooves (i.e. deeper than the dotted lines 32). The wick
stop trench may be slightly deeper than the V-grooves (e.g. 50,
100, or 200 microns deeper than the V-grooves); the wick stop
trench may also be slightly shallower than the V-grooves (e.g. 5,
10, or 20 microns shallower. In either case, the wick stop trench
must be deep enough to stop capillary action of adhesive between
the V-groove and a fiber disposed in the V-groove. The required
depth may depend on the size of the optical fiber, the viscosity of
the adhesive, and the wetting properties of the chip, optical fiber
and adhesive.
[0040] The trench width 34 can be in the range of 20-500 microns.
Preferably, the width 34 is about 150 microns, or in the range of
100-200 microns. The trench width should be kept relatively short
to prevent microbending of an optical fiber in the V-groove. The
trench can be relatively wide (e.g. 1-3 millimeters) although this
is not preferred.
[0041] Preferably, the wick stop trench 26 is centered on a
midpoint 39 of the V-grooves so that the V-grooves are divided into
sections 40 of equal length. Alternatively, the wick stop trench 26
is located off the midpoint 39 so that the V-grooves are divided
into unequal lengths. In this case, each section of the V-grooves
should be at least 50-200-500 microns long. More preferably, each
length is at least 2-4 millimeters long.
[0042] FIG. 3a shows a side view of an optical fiber array
according to the present invention. An optical fiber 42 is disposed
in the V-groove 24. Dotted line 32 indicates the bottom of the
V-groove 24. A lid 44 is disposed on top of the optical fiber and
holds the fiber 42 in the V-groove. The lid 44 can be made of
glass, silica or silicon, for example. The wick stop trench 26 may
be filled with adhesive, or may be empty. Also, the lid 44 can be
replaced with a V-groove chip (with or without a wick stop trench).
A front face 47 of the array is preferably polished for optical
connection to other optical components.
[0043] FIG. 3b shows an alternative embodiment where the lid 44
only covers one front length 45 of the V-groove. This embodiment
may be useful if hardened adhesive residue 43 is adhered to the
optical fiber 42 because such adhesive residue can prevent the
proper placement of the lid.
[0044] FIGS. 4a-b illustrate a method for making the chips of the
present invention. In FIG. 4a, a V-groove 24 is formed in a single
crystal silicon substrate 20 using wet anisotropic etching.
Optionally, a recessed area 46 for bonding coated fibers is etched
to a level as deeper than the V-grooves. Next, in FIG. 4b, the wick
stop trench 26 is cut across the V-groove 24, dividing the V-groove
into front groove section 24t and rear groove section 24k. Groove
sections 24k and 24t can be equal or unequal in length. Preferably,
the trench 26 is cut using a dicing saw or similar device.
Preferably, a large number of V-groove chips are cut with the
dicing saw while still connected in wafer form.
[0045] FIGS. 5a-5c illustrate a preferred method of the present
invention for securing an optical fiber in a V-groove chip
according to the present invention. First, in FIG. 5a, the optical
fiber 42 is disposed in the front 24t and rear 24k V-groove
sections. The rotational alignment of the fiber may be adjusted,
and the longitudinal alignment of the fiber may be adjusted. Next,
in FIG. 5b, adhesive 48 (e.g. UV curable epoxy) is disposed in the
rear groove section 24k. The adhesive 48 travels by capillary
action (wicking) along the rear groove section 24k and stops at the
wick stop trench 26. The adhesive may partially fill the wick stop
trench 26. The adhesive does not travel to the front groove section
24t because of the wick stop trench 26. Next, the adhesive in the
rear groove section 24k is hardened using UV illumination.
Hardening the adhesive 48 secures the rotational and longitudinal
alignment of the optical fiber 42. At this point, the fiber 42 is
not attached to the front groove section 24t.
[0046] It is noted that the fiber may not be accurately disposed in
the front groove section 24t during or after adhesive 48 is set in
the rear groove section 24k. This is because the fiber 42 is not
pressed into the front groove section 24t. FIG. 5c illustrate a
possible mispositioning of the fiber in the front groove section
24t.
[0047] Next, in FIG. 5d, a lid 44 is placed on top of the fiber 42.
In the embodiment shown, the lid 44 only covers the front groove
section and does not cover the rear groove section 24k. Placement
of the lid presses the optical fiber into the front groove section
24t thereby providing accurate positioning of the fiber. The
rotational and longitudinal alignment of the fiber is fixed by the
adhesive 48 in the rear groove section before the lid is placed.
After the lid is placed, adhesive is disposed in the front groove
section 24t from either the wick stop trench 26 or the front face
47 and hardened using UV illumination. Since the
rotational/longitudinal alignment and position of the fiber with in
the V-groove are set independently in two separate gluing steps,
each alignment can be done with higher precision. In the prior art,
rotational/longitudinal alignment and pressing of the fiber into
the groove must be performed in the same gluing step.
[0048] The ability of the wick stop trench 26 to stop the adhesive
travel is an essential feature of the present invention. Since the
wick stop trench can control the movement of liquid adhesive,
different portions of the optical fiber 42 can be glued in distinct
gluing steps. The ability to glue different portions of the fiber
in distinct steps provides for improved fiber alignment and other
benefits in certain kinds of fiber arrays. This is because
longitudinal/rotational alignment can be fixed in a separate step
from pressing the fiber into the groove.
Example 1
Polarization-maintaining Optical Fiber Array
[0049] The present invention is particularly well suited for making
polarization-maintaining (PM) optical fiber V-groove arrays. A
method for making PM fiber V-groove arrays according to the present
invention includes the following steps:
[0050] 1) Place a PM fiber in the rear groove section and front
groove section.
[0051] 2) Rotate the PM fiber until properly aligned.
[0052] 3) Apply adhesive to the rear groove section and cure the
adhesive, thereby fixing the rotational alignment.
[0053] 4) Place a lid on the PM fiber and press the fiber into the
front groove section to accurately position the fiber in the front
groove section.
[0054] 5) Apply adhesive to the front groove section and cure
adhesive.
EXAMPLE 2
Optical Fiber Array with Longitudinally Located Fibers.
[0055] FIG. 6 shows an optical fiber array where the optical fibers
42a-c are located longitudinally. Endfaces 50 are not flush
(coplanar) with the front face 47 of the array and substrate. A
method for making fiber V-groove arrays with longitudinally located
fibers according to the present invention includes the following
steps:
[0056] 1) Place a fiber in the rear groove section and front groove
section.
[0057] 2) Longitudinally move the fiber until properly aligned.
[0058] 3) Apply adhesive to the rear groove section and cure the
adhesive, thereby fixing the longitudinal alignment.
[0059] 4) Place a lid on the fiber and press the fiber into the
front groove section to accurately position the fiber in the front
groove section.
[0060] 5) Apply adhesive to the front groove section and cure
adhesive.
[0061] It is noted that a jig having fiber stops can be used to
longitudinally locate the optical fibers in this embodiment.
[0062] It is noted that the present invention can be used in any
situation where multiple gluing steps are desired. For example,
different adhesives can be used in different groove sections. This
may be useful, for example, where an adhesive having good polishing
properties is used in the front groove section and a different
adhesive having good adhesion/expansion properties is used in the
rear groove section.
[0063] It is also noted that the present invention includes
embodiments having more than one wick stop trench. FIG. 7, for
example, shows a side view of a V-groove chip having two wick stop
trenches 26a, 26b dividing the V-groove into three groove sections
24x, 24y, 24z.
[0064] It is also noted that the wick stop trench does not need to
be perpendicular to the V-groove. The wick stop trench can be
located at almost any angle provided that the wick stop prevents
the wicking of adhesive. The wick stop trench could be oriented at
60 degrees with respect to the V-grooves, for example. FIG. 8 shows
a top view of an embodiment with a nonperpendicular wick stop
trench.
[0065] FIG. 9 is a side view of a fiber array made according to a
preferred embodiment of the present invention. The wick stop trench
is filled (filled up to the bottom of the optical fiber) with
hardened adhesive 52. Although the wick stop trench 26 functioned
as a wick stop when liquid adhesive was placed into the rear groove
section 24k, in the step of adhering the fiber to the front groove
section 24t of the array, the wick stop trench 26 is filled with
adhesive. The liquid adhesive flows from the wick stop trench into
the front groove section 24t. Filling the wick stop trench with
adhesive simplifies the task of adhering the front portions of the
optical fibers to the front V-groove section, and provides other
benefits.
[0066] FIGS. 10a-10b illustrate a preferred method for making the
fiber array with a filled wick stop trench. FIGS. 10a-10b Are
close-up side views of the wick stop trench and optical fiber and
only show a portion of the V-groove chip and fiber.
[0067] FIG. 10a The optical fiber is disposed in the V-groove 24k
24t. Liquid adhesive (e.g. UV-curable epoxy) is applied to the rear
groove section 24k, forming a fillet 54 due to surface tension
forces. The wick stop trench 26 prevents the liquid adhesive from
flowing into the front groove section 24t. The liquid adhesive is
cured so that the fillet 54 becomes solid. Before application and
curing of the adhesive in the rear groove section 24k, longitudinal
and/or rotational alignment of the optical fiber may be
provided.
[0068] FIG. 10b The wick stop trench is filled with liquid adhesive
56. Preferably, the wick stop trench is filled completely (up to
the top surface of the V-groove chip). The liquid adhesive flows
into the front groove section 24t by capillary action as the wick
stop trench is filled. The adhesive in the wick stop and front
groove section is then cured. A fillet boundary 58 may be present.
The fillet boundary 58 indicates that the two adhesive applications
were solidified in separate steps.
[0069] An adhesive-filled wick stop trench provides several
distinct advantages:
[0070] 1) A filled wick stop trench provides improved strength for
the V-groove chip. If the wick stop trench is not filled, then the
chip is substantially weakened by the wick stop trench.
[0071] 2) Applying adhesive to the front groove sections by filling
the wick stop trench simplifies the task of applying adhesive to
the front groove sections. Only a single adhesive application is
necessary; a separate adhesive application is not required for each
optical fiber in the fiber array.
[0072] 3) Filling the wick stop trench reduces the occurrence of
trapped air bubbles in the fiber array. Trapped air bubbles are
often formed if the wick stop trench is not filled and a lid is
glued onto the fiber array. Trapped air bubbles are best avoided
because they can cause adhesive delamination when the array is
exposed to temperature cycling.
[0073] Although the fillet boundary is a preferred feature of the
present invention, it is not essential. The present invention
includes a fiber array having a wick stop trench filled with
adhesive.
[0074] FIG. 11 shows a magnified side view of the filled wick stop
trench having a fillet boundary 58 created by two separate
application and solidification steps. The fillet boundary will be
readily apparent if different adhesives are used in the front and
rear groove sections. If the same adhesive is used in the front and
rear groove sections, the fillet boundary may be difficult to
observe. An optical fiber array made according to the preferred
method of the present invention will have a fillet boundary,
although the fillet boundary may be difficult to observe.
[0075] FIG. 12 shows an alternative embodiment where the fillet
boundary extends to the bottom of the wick stop trench. In this
embodiment, the bottom of the wick stop trench was partially wetted
by the first adhesive application.
[0076] FIG. 13 shows another embodiment of the present invention
where both the front groove section 24t and rear groove section 24k
are filled with liquid adhesive so that two fillets 54, 60 are
formed. The embodiment of FIG. 13 is made by applying liquid
adhesive to the front groove section instead of the wick stop
trench.
[0077] FIG. 14 shows yet another embodiment where the wick stop
trench of the fiber array of FIG. 13 is filled with liquid adhesive
61 (in a third adhesive application). The fiber array of FIG. 14
has two fillet boundaries 58, 62.
[0078] It is noted that a fiber array made according to the method
of the present invention will have a fillet boundary.
[0079] It is further noted that the V-groove does not necessarily
have a pointed, V-shaped bottom. The V-groove can have a flat
bottom. V-grooves with flat bottoms are commonly used in the art
and are readily made in silicon using wet anisotropic etching
techniques.
[0080] Although the present invention has been described with
reference to using V-grooves, the present invention can be used
with grooves of any cross sectional shape. For example, the present
invention can be used with grooves having U-shapes or rectangular
shapes. Also, the wick stop trench can have essentially any shape
(e.g. V-shaped, U-shaped), provided that it functions as a wick
stop.
[0081] Also, the V-groove chips of the present invention can be
made of materials other than silicon including ceramic, quartz,
plastic and metal.
[0082] It will be clear to one skilled in the art that the above
embodiment may be altered in many ways without departing from the
scope of the invention. Accordingly, the scope of the invention
should be determined by the following claims and their legal
equivalents.
* * * * *