Optical waveguide module

It is an object of the present invention to provide an optical waveguide module in which, under the high temperature and high humidity, degradation of characteristics does not occur and which has strength to the oscillation, simple structure, and high reliability. A module unit 30 is formed by bonding a connector 32 provided at one end of a single-optical fiber cable 22 and a connector 31 provided at one end of a ribbon optical fiber cable 21 at both ends of a waveguide substrate 35 having a 1.times.4 branch optical waveguide by an adhesive having light transmission properties. The module unit 30 is provided in a housing 10, and at least a connecting portion between the optical waveguide and the optical fiber cable is covered with the resin contained in the housing 10. The housing 10 is sealed with a cover unit 15, and the single-optical fiber cable 22 and the ribbon optical fiber cable 21 are tightly inserted into a respective hole at end walls of the housing 10 and led out to the outside.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an optical waveguide module which is used 
in an optical fiber communication network and others. 
2. Related Background Art 
An optical waveguide module comprising, e.g., an optical branching filter 
and others, generally comprises a module unit which is formed by bonding 
end faces of optical fiber cables with a respective end face of an optical 
waveguide and which is housed in a housing. In the optical waveguide 
module, under the high temperature and high humidity, an adhesive which is 
used in the connecting portion between the optical waveguide and the 
optical fibers moistens and is degraded, which causes the degradation of 
characteristics: increase of loss and light reflection, degrade of tensile 
strength. 
Therefore, the housing is sealed with, e.g., a nitrogen gas (N.sub.2). 
Alternatively, the housing is filled with a jelly-like resin. As such 
conventional techniques, for example, a technique disclosed in "Japanese 
Patent Laid-Open No. HEI 5-27139 (27139/1993)" is known. As a technique of 
coating the outside of the housing with a resin, for example, a technique 
disclosed in "Japanese Patent Laid-Open No. HEI 5-45531 (45531/1993)" is 
known. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an optical waveguide 
module with high weather resistance and the long-term high reliability. 
It is one object of the present invention to provide an optical waveguide 
module comprising a module unit having a waveguide device with a waveguide 
substrate on which an optical waveguide is formed, and a fiber connector 
for holding a optical fiber cable, the waveguide device being bonded to 
the fiber connector; a housing for housing the module unit, the housing 
having a hole through which the optical fiber is inserted into inside of 
the housing and is led out to outside of the housing, and the housing a 
depth larger than a thickness of the module unit; a member made of a resin 
covering a bonding portion between said waveguide device and the fiber 
connector, the member being filled in the housing, the material being 
introduced in liquid-state into the inside of the housing to immerse said 
bonding portion and thereafter being cured in the inside of the housing; 
and a cover unit having a substantially flat shape for sealing said 
housing. 
In this specification and claims, a waveguide-device means a device 
including a wave-guide substrate itself, a device in which various optical 
elements are added into the wave-guide substrate, or a device in which a 
waveguide forming surface of the waveguide substrate is covered with a 
resin etc. 
According to the present invention, since the housing has a depth deeper 
than a thickness of the module unit, a connecting portion between the 
waveguide device and the fiber connector can be immersed in a liquid resin 
composition by filling the liquid resin composition into the housing, and 
as the resin is cured, the connecting portion can be covered with the 
resin member. Therefore, the module unit can be housed in a container 
constituted with the housing and the cover unit, and the module unit is 
contained in the resin member, so that the characteristics are hardly 
degraded caused by the moisture. 
Further, a protective cover is provided at the housing so as to project to 
the outside, which prevents the stress to be applied to the optical 
fibers, and if the protective cover is constituted with an upper member 
and a lower member, works of assembling the module unit and housing the 
module unit in the housing can be made easier. 
Furthermore, since the cover is made flat, the waveguide module can be made 
very thin, and if a protrusion is formed on the inner rim of the housing, 
this protrusion serves as a sluice for the liquid resin composition. The 
housing is bonded with the cover unit at the outer rim by the adhesive. 
The present invention will become more fully understood from the detailed 
description given hereinbelow and the accompanying drawings which are 
given by way of illustration only, and thus are not to be considered as 
limiting the present invention. 
Further scope of applicability of the present invention will become 
apparent from the detailed description given hereinafter. However, it 
should be understood that the detailed description and specific examples, 
while indicating preferred embodiments of the invention, are given by way 
of illustration only, since various changes and modifications within the 
spirit and scope of the invention will become apparent to those skilled in 
the art from this detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The embodiments will be described below. The same components are 
represented by the same reference numerals and the repetitive description 
on the same devices is omitted. 
FIGS. 1-5 show a process of assembling an optical waveguide module 
according to the first embodiment. Its structure will be apparent from the 
explanation of this process. As shown in FIG. 1, a housing 10 has a long 
box shape, and a large-diameter protective cover 11 having a through hole 
to which a ribbon optical fiber cable 21 can be inserted is formed at the 
housing 10 so as to protrude from one end of the housing 10, and a 
small-diameter protective cover 12 having a through hole to which a 
single-optical fiber cable 22 can be inserted is formed so as to protrude 
from the other end. The ribbon optical fiber cable 21 is formed by coating 
four bare fibers 23.sub.1 -23.sub.4 made of silica glass individually with 
a resin layer (not shown), arranging these fibers in a plane, and 
integrating the fibers with internal and external resin layers (integral 
coating layer 24). The integral coating layer 24 touches the inner surface 
of the hole of the large-diameter protective cover 11. The single-optical 
fiber cable 22 is formed by coating one bare fiber 23.sub.0 with external 
and internal resin single-optical fiber coating layers 25. The 
single-optical fiber coating layers 25 touches the inner surface of the 
hole of the small-diameter protective cover 12. 
The module unit 30 is fabricated by connecting fiber connectors 31, 32 at 
both ends of a waveguide substrate 35. With the ribbon optical fiber cable 
21 and the single-optical fiber cable 22 are inserted into the 
large-diameter protective cover 11 and the small-diameter protective cover 
12, respectively, the module unit 30 is assembled as shown in FIGS. 1-2. 
First, the bare fibers 23.sub.1 -23.sub.4 and the bare fiber 23.sub.0 are 
exposed from the ends of the ribbon optical fiber cable 21 and the 
single-optical fiber cable 22, and set in V-shaped grooves of a 
multi-fiber V-shaped groove substrate 31A and a single-fiber V-shaped 
groove substrate 32A, respectively. Next, presser plates 31B and 32B are 
put on the substrates and adhered thereto to form a multi-fiber connector 
31 which holds the bare fibers 23.sub.1 -23.sub.4 and a single-fiber 
connector 32 which holds the bare fiber 23.sub.0. Note that the V-shaped 
groove substrates 31A and 32A are fabricated by mechanically grinding a 
silicon substrate or by physically and chemically etching a silicon 
substrate. 
FIG. 2 shows a state of an assembled module unit 30, and a waveguide 
substrate 35 lies between these connectors 31, 32. A 1.times.4 branch type 
optical waveguide is formed on a surface of the waveguide substrate 35. 
Such an optical waveguide substrate 35 is fabricated by depositing a plane 
lower cladding layer, a 1.times.4-branch-lines-shaped core layer and a 
plane upper cladding layer, and vitrifying these layers, using a method of 
depositing SiO.sub.2 fine particles on a surface of a silicon substrate 
(FHD: flame hydrolysis deposition method). Next, both end faces of the 
waveguide substrate 35 are fixed with the end faces of the multi-fiber 
connector 31 and the single-fiber connector 32 by a photocuring adhesive 
(e.g., ultra violet ray curing adhesive). A protrusion 13 is provided on 
the inner rim of the housing 10 so that the inner rim is high and the 
outer rim is low. 
With a state shown in FIG. 2, as the ribbon optical fiber cable 21 and the 
single-optical fiber cable 22 are pulled toward both sides, the module 
unit 30 is housed in the housing 10. Here, the depth of the housing 10 is 
sufficiently large as compared with the thickness of the module unit 30 to 
entirely store the module unit 30 in the housing 10. The housing 10 is 
fixed at the central part of the base of the module unit 30 by the 
adhesive, and the integral coating layer of the ribbon optical fiber cable 
21 and the single-fiber coating layer 25 are fixed to the large-diameter 
protective cover 11 and the small-diameter protective cover 12 by the 
adhesive, respectively. As apparent from FIG. 2, the optical fiber cables 
21 and 22 and the waveguide substrate 35 are arranged substantially on one 
line. Accordingly, the optical fiber cables 21 and 22 are practically not 
bent. Therefore, this structure is such that excessive stress is not 
applied to the connecting portion between the optical fiber cables 21 and 
22 and the waveguide substrate 35. 
Next, as shown in FIG. 3, a liquid resin 40 containing a jelly-like resin 
composition is injected and filled into the housing 10. Here, since the 
housing 10 has a depth larger than the thickness of the module unit 30, 
the entire module unit 30 is immersed in the liquid resin 40. Further, 
since the protrusion 13 is formed along the inner rim of the housing 10, 
the liquid resin 40 hardly overflows. 
Next, the housing 10 is sealed with a cover unit 15. A state before sealing 
is shown in FIG. 4, and a state after sealing is shown in FIG. 5. Here, 
the cover unit 15 has a groove (not shown) along the perimeter of the 
lower surface corresponding to the protrusion 13 formed along the inner 
rim of the housing 10. The adhesive is applied to the outer rim 14 of the 
housing 10, and the cover unit 15 is adhered thereto. As described above, 
the optical waveguide module according to the present embodiment is 
completed. 
In the above embodiment, the housing 10 and the cover unit 15 can be made 
of ceramic, plastic or metal, e.g., Al (aluminum). Various kinds of 
adhesives such as an adhesive which cures upon light irradiation 
(photocuring adhesive) such as a UV ray, an adhesive which cures upon 
application of heat (thermosetting adhesive), or an adhesive which cures 
upon mixture of two liquids: a main agent and a curing agent, can be 
utilized for an adhesive between the large-diameter protective cover 11 
and the integral coating layer 24, an adhesive between the small-diameter 
protective cover 12 and the single-fiber coating layer 25, an adhesive for 
the formation of the multi-fiber connector 31 and the single-fiber 
connector 31, and an adhesive between the housing 10 and the cover unit 
15. For example, epoxy adhesive EPO-TEC 302-3 (manufactured by RIKEI CO., 
LTD) and epoxy adhesive STAYCAST 2057 (manufactured by GRACE JAPAN CO., 
LTD) are used for an adhesive between the housing 10 and the cover unit 
15, and the EPO-TEC is used for the formation of the multi-fiber connector 
31 and the single-fiber connector 32. Epoxy adhesive OPTDAIN UV-2100, 3100 
(manufacture by DAIKIN KOUGYOU COMPANY) is used for the connection of the 
waveguide substrate 35, the multi-fiber connector 31 and the single-fiber 
connector 32. The OPTDAIN contains a material having light (signal light) 
transmission properties in which loss hardly occurs, and is suitable for 
an adhesive between the optical waveguide and the end face of the optical 
fiber. 
On the other hand, as the liquid resin 40 for filling, a resin which, 
before curing, is liquid with high fluidity and which, after curing, is 
solid, e.g., gel, having a suitable elasticity is desirable. In 
particular, the preferred properties are as follows. First, it is superior 
in fluidity before curing and able to fill a narrow space. Second, it is 
superior in stickiness and adhesion, and has a sealing property and a 
moisture resistance. Third, it is comparatively soft after curing and 
easily transformed by small weight or pressure. Fourth, it has a low 
elastic module after curing and able to relax the stress due to thermal 
expansion. Fifth, it has an oscillation absorptivity after curing. 
SILICONE GEL (manufactured by SHINETU SILICONE COMPANY) is an example of 
such a liquid resin 40. XNR-4950 (manufactured by NIPPON CHIBA GAIGI 
COMPANY) which is a super-reflective thermosetting epoxy resin, or 
PERU-URETHANE MU-102A/B (manufactured by NIPPON PERUNOX CO., LTD) which is 
a two liquid mixture curing polyurethane resin can be used. 
Next, referring to FIG. 6-FIG. 9, an optical waveguide module of the second 
embodiment will be explained. In this embodiment, the module is also a 
1.times.4 branch type optical waveguide module, and the components as same 
as FIG. 1-FIG. 5 are represented by the same reference numerals. As shown 
in FIG. 6 and FIG. 7, in this embodiment, the large-diameter protective 
cover 11 and the small-diameter protective cover 12 at both sides of the 
housing 10 are constituted with lower half units 11A and 12A and upper 
half units 11B and 12B, respectively. The lower half units 11A and 12A and 
the housing 10 are integrally formed. These are easily formed of a 
polycarbonate resin or a ceramic material. This is because the 
large-diameter protective cover 11 and the small-diameter protective cover 
12 are divided into the upper and lower half units. 
Further, since the large-diameter protective cover 11 and the 
small-diameter protective cover 12 are divided into the upper and lower 
half units, a module unit 30 is easily assembled. That is, in the first 
embodiment, as shown in FIG. 1 and FIG. 2, after the ribbon optical fiber 
cable 21 and the single-optical fiber cable 22 are inserted into the 
through holes of the large-diameter protective cover 11 and the 
small-diameter protective cover 12, the formation of the fiber connector 
31 and the single-fiber connector 32, and the connection of the 
multi-fiber connector 31 and the single-fiber connector 32 to the 
waveguide substrate 35, that is, the assembling of the module unit 30 are 
performed. According to the present embodiment, before the optical fiber 
cables 21 and 22 are installed in the housing 10, the module unit 30 can 
be formed. Then, after the module unit 30 is completed, it is housed in 
the housing 10 without bending the optical fiber cables, so that the 
module unit 30 is not damaged by the excessive stress in the manufacturing 
process. 
As shown in FIG. 7, the module unit 30 is formed by connecting a 
multi-fiber connector 31 for a ribbon optical fiber cable 21 and a 
single-fiber connector 32 for a single-optical fiber cable 22 at both 
sides of a waveguide substrate 35. Next, the module unit 30 is housed in 
the housing 10. The ribbon optical fiber cable 21 is set and adhered in a 
groove of the lower half unit 11A of the large-diameter protective cover 
11, and the single-optical fiber cable 22 is set and adhered in a groove 
of the lower half unit 12A of the small-diameter protective cover 12. 
Next, the upper half units lib and 12B are bonded with the lower half 
units 11A and 12A, so that the housing 10 having the large-diameter 
protective cover 11 and the small-diameter protective cover 12, protruding 
from the both ends is formed. 
As shown in FIG. 7, the upper half units 11B and 12B have substantially T 
shapes with holding parts for the optical fiber cables 21 and 22 as 
vertical axes, and their horizontal parts are put in cutouts at both ends 
of the housing 10, whereby the housing 10 has a box shape. Accordingly, as 
shown in FIG. 8, a liquid resin 40 is injected into the housing 10, and 
the entire module unit 30 can be immersed in the liquid resin 40. FIG. 9 
is a perspective view of a completed optical waveguide module. The same 
adhesive and liquid resin 40 as the first embodiment can be used in this 
embodiment. According to the second embodiment, after the module unit 30 
is assembled, it is set in the housing 10, so that the process is very 
simple and any excessive stress is not applied to the optical fiber cables 
21 and 22. Further, the formation of the housing 10 is made easier. 
Ceramics or plastic can be used as a material of the housing 10. Further, 
the adhesive between the optical fiber cables 21 and 22 and the protective 
covers 11 and 12 of the housing can be made perfect, so that the 
improvement of the mechanical strength and the improvement of sealing 
property can be achieved. 
FIG. 10 is a perspective view of an optical waveguide module according to 
the third embodiment, and FIG. 11 is its vertical sectional view. In this 
embodiment, a ribbon optical fiber cable 21 and a single-optical fiber 
cable 22 are inserted into holes 152 at both ends of a housing 10 from the 
inside, and a module unit 30 is assembled and housed in the housing 10. 
Next, the housing 10 is sealed with a cover plate 15 having a hole 151 at 
the central portion. 
The above module unit 30 is formed by connecting the optical fiber cables 
21 and 22 at both ends of an optical waveguide substrate 35. The optical 
waveguide substrate 35 is a silica waveguide substrate which is 
constructed as a 1.times.8 branch filter on an Si substrate by a flame 
hydrolysis deposition method. Further, connectors 32 and 31 holding the 
single-optical fiber cable 22 and the arrayed-multi-optical fiber cable 21 
are fixed at both ends of the waveguide substrate 35 by an adhesive 301, 
respectively. 
The signal light incidence side of the optical waveguide is coupled and 
aligned with the single-optical fiber cable 22 so that its optical axis 
matches an optical axis of an optical fiber 23 led out from the 
single-optical fiber cable 22 through the left-hand side single-fiber 
connector 32. The signal light emerging side, which is branched into 
plural (eight), of the optical waveguide is coupled and aligned with the 
waveguide substrate 35 so that their optical axes match optical axes of 
arrayed eight optical fibers 23 led out from the ribbon optical fiber 
cable 21 through the right-hand side multi-fiber connector 31. 
Each connector 31 and 32 has a V-shaped groove formed on an Si chip, and 
the optical fibers 23 are inserted in the V-shaped grooves. End faces of 
the connectors 31 and 32 are fixed at the end faces of the waveguide 
substrate 35 using the adhesive 301. Further, for the adhesive 301, an 
ultra violet ray curing adhesive which is transparent against signal light 
and which has a refractive index matching with refractive indices of the 
optical waveguide and the optical fibers 23 is used. 
The holes 152 are formed at both end walls of the housing 10. When the 
module unit 30 is provided in the housing 10, the single-optical fiber 
cable 22 and the ribbon optical fiber cable 21, which are connected to the 
connectors 31 and 32, respectively are inserted into the respective hole 
152 and led out to the outside of the housing 10. Note that a gap between 
the hole 152 and the single-optical fiber cable 22 and a gap between the 
hole 152 and the ribbon optical fiber cable 21 are preferably small, and 
these gaps are filled with the adhesive to fix the single-optical fiber 
cable 22 and the ribbon optical fiber cable 21 at the housing 10. 
As described above, the module unit 30 is provided in the housing 10, and 
the single-optical fiber cable 22 and the ribbon optical fiber cable 21 
are led out to the outside of the housing 10. Thereafter, a jelly-like 
resin 40, e.g., a silicone gel as an elastic filling material is poured 
into the housing 10 (see FIG. 11). Next, an opening of the housing 10 is 
sealed with the cover plate 15 having the hole 151. 
In the above case, a larger amount of the jelly-like resin 40 is preferable 
and the resin 40 may fill up the housing 10 in order to prevent the 
moisture from moistening the adhesive 301 of the connecting portion 
between the optical waveguide and the bare optical fibers 23. However, in 
this case, the resin 40 may be expanded according to heat depending upon 
the working temperature and its volume becomes larger than the volume of 
the inner space of the housing 10. If the housing 10 has airtight 
structure, the module unit 30 is expanded and the optical connecting 
portion may be damaged. Thus, in the present embodiment, the hole 151 is 
formed in the cover plate 15, so that a part of the thermally expanded 
resin 40 flows out through the hole 151, which solves the problem of the 
expansion of the module unit 30. 
The inventors of the present application experimented a damp heat test 
(60.degree. C., 90% RH, 200 hours) in a case of the module unit 30 
provided in the housing 10 being covered with the jelly-like resin 40 and 
in a case of not covered with the resin 40. The results are shown in FIG. 
12. In a graph shown in FIG. 12, a vertical axis shows the amount of a 
reflection decrease, a horizontal axis shows the amount of a testing time 
in damp-heating and a white circle shows a the result in a module unit 
covered with jelly-like resin and a black circle shows the result in a 
module unit which is not covered with the jelly like resin. It is 
recognized from the graph that a reflective characteristic of signal light 
is degraded at the connecting portion due to moisture moistening the 
adhesive 301. 
In an optical waveguide module of the fourth embodiment shown in FIG. 13, a 
cover plate 15 does not have a hole, which is different from the third 
embodiment, and a module unit 30 and a jelly-like resin 40 are housed in a 
housing 10, and the housing 10 is sealed by the cover plate 15. The 
remaining structure is the same as the third embodiment. In the fourth 
embodiment, since the housing 10 is sealed, the optical waveguide module 
may be used in water. 
In an optical waveguide module of the fifth embodiment shown in FIG. 14, 
the jelly-like resin 40 to be contained in the housing 10 does not fill up 
the housing 10, which makes a space therein. An amount of the resin 40 is 
limited to the amount such that the amount of the expanded resin 40 does 
not become larger than the volume of the inner space of the housing 10 
even though the resin 40 is expanded according to heat depending upon the 
working temperature. Further, the cover plate 15 does not have a hole, and 
the housing 14 is sealed with the cover plate 15. Therefore, a coefficient 
of thermal expansion of the resin 40 is large, and in the case of the 
resin 40 thermally expanded, the expanded resin 40 only occupies the inner 
space of the housing 10, and the stress due to the resin 40 is not applied 
to the module unit 30. Accordingly, the connection loss between the 
optical waveguide and the end faces of the optical fibers does not 
increase. 
In the sixth embodiment shown in FIG. 15, the housing 10 is divided by two 
diaphragms 101 and 102, and connecting portions between the optical 
waveguide substrate 35 and the optical fibers 23 are located in two 
regions formed between the diaphragm 101 and a side wall and between the 
diaphragm 102 and a side wall. Further, the jelly-like resin 40 is 
contained only in these region and provided for covering at least the 
connecting portions. In this embodiment, only a minimum amount of the 
jelly-like resin 40 required for covering at least the connecting portions 
is contained in the housing 10, which makes the amount of the resin 40 
very little. Further, since the sufficient internal space is formed at the 
upper part in the housing 10 and especially the upper surface of the 
waveguide substrate 35 is not covered with the jelly-like resin 40, this 
embodiment is effective in a case that an optical device such as an 
isolator or others, an electrode for switching, or others are integrated 
on the upper surface of the waveguide substrate 35. 
In the above-described embodiments, the silica waveguide formed on a 
silicon substrate is used as the optical waveguide substrate 35 but 
besides this, the optical waveguide substrate can be made of 
semiconductor, dielectric substance, glass or others. For the jelly-like 
resin 40, a silicone rubber, a silicone grease or others can be used 
besides a silicone gel, and especially a resin which has high water 
resistance is desirable. The module unit 30 may be fixed at the base of 
the housing 10 (FIG. 1-FIG. 9), may be floated in the liquid resin 40 
(FIG. 10-FIG. 15), or may comprise a protrusion part 105 for supporting 
the module unit 30 at the base of the housing 10 as shown in FIG. 16. The 
module unit 30 is fixed with the upper surface of the protrusion part 105, 
and the large-diameter protective cover 11 is fixed with the ribbon 
optical fiber cable 21 by the adhesive 201, and the small-diameter 
protective cover 12 is fixed with the single-optical fiber cable by the 
adhesive 202. 
The structure of a joint of the cover unit 15 with the rim of the housing 
10 may be constructed as the horizontal sectional views of FIG. 17-FIG. 
19. In FIG. 17, cutouts are formed on the cover unit 15 to fit with the 
rim of the housing 10, and an adhesive 108 lies therebetween. In FIG. 18, 
the protrusion is formed along the inner rim of the housing 10, and the 
protrusion is formed along the perimeter of the cover unit 15 
corresponding to the outer rim of the housing 10. The adhesive 108 lies 
between the outer rim of the housing 10 and the protrusion of the cover 
unit 15. In FIG. 19, the protrusion is formed along the inner rim of the 
housing 10, and the groove is formed along the perimeter of the cover unit 
15 to fit with the protrusion on the rim of the housing 10. The adhesive 
108 lies between the outer rim of the housing 10 and the perimeter of the 
cover unit 15. 
Thus, as described above, according to the present invention, a housing the 
depth of which is larger than the thickness of a module unit, so that the 
module unit is easily immersed into a liquid resin composition. Therefore, 
a connecting portion between an optical waveguide and optical fiber cables 
is covered with an elastic filling material such as, rubber, a jelly-like 
resin or others, so that the prevention of the moisture from moistening 
the adhesive of the connecting portion is ensured. Further, the housing is 
sealed by a cover unit, which improves the weather resistance. Therefore, 
an optical waveguide module in which, under the high temperature and high 
humidity, degradation of characteristics, such as increase of loss and 
light reflection, degrade of tensile strength or others does not occur and 
which has strength to the oscillation, simple structure, and high 
reliability can be achieved. 
From the invention thus described, it will be obvious that the invention 
may be varied in many ways. Such variations are not to be regarded as a 
departure from the spirit and scope of the invention, and all such 
modifications as would be obvious to one skilled in the art are intended 
to be included within the scope of the following claims. 
The basic Japanese Applications No. 188348/1993 filed on Jul. 29, 1993 and 
No. 154916/1994 filed on Jul. 6, 1994 are hereby incorporated by 
reference.