U.S. patent application number 10/462385 was filed with the patent office on 2008-05-08 for device for transferring optical signals by means of planar optical conductors.
Invention is credited to Harry Schilling.
Application Number | 20080107378 10/462385 |
Document ID | / |
Family ID | 7950520 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080107378 |
Kind Code |
A9 |
Schilling; Harry |
May 8, 2008 |
Device for transferring optical signals by means of planar optical
conductors
Abstract
What is described here is a method of or a device for
transferring optical signals. An optical conductor including a
light-conducting core, which has at lest two parallel interfaces
provided with coatings that result in a reflection of the light
guided in the light-conducting core, comprises at least one means
for coupling the emitter or the receiver, respectively, by
diffraction, refraction or diffusion.
Inventors: |
Schilling; Harry;
(Eichstatt, DE) |
Correspondence
Address: |
DAFFER MCDANIEL LLP
P.O. BOX 684908
AUSTIN
TX
78768
US
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Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20040252943 A1 |
December 16, 2004 |
|
|
Family ID: |
7950520 |
Appl. No.: |
10/462385 |
Filed: |
June 16, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/DE01/04575 |
Dec 7, 2001 |
|
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10462385 |
Jun 16, 2003 |
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Current U.S.
Class: |
385/37 |
Current CPC
Class: |
G02B 6/4206 20130101;
G02B 6/00 20130101; G02B 6/26 20130101; G02B 6/2817 20130101; G02B
6/02 20130101; G02B 6/4202 20130101; G02B 6/42 20130101; G02B 6/43
20130101; G02B 2006/12107 20130101; G02B 6/4214 20130101; G02B 6/34
20130101; H05K 1/0274 20130101; G02B 6/2852 20130101 |
Class at
Publication: |
385/037 |
International
Class: |
G02B 6/34 20060101
G02B006/34 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2000 |
DE |
20021834.4 |
Feb 2, 2001 |
DE |
10106297.4 |
Jun 8, 2001 |
DE |
PCT/DE01/02120 |
Claims
1. Device for transferring optical signals, comprising at least one
preferably planar optical conductor composed of a light-conducting
core having at least two parallel interfaces in the regions
provided for the conduction of light, which are provided with
coatings resulting in a reflection of the light guided in the
light-conducting core, and at least one source for the emission of
light, at least one receiver for receiving light, at least one
means for coupling said source or said receiver, respectively to
said optical conductor, characterized in that said means comprises
or comprise, respectively, optical coupling gratings for
redirecting the light by diffraction.
2. Device according to claim 1, characterized in that at least one
optical grating is provided on the outside face of a coating.
3. Device according to any of the preceding claims, characterized
in that at least one optical grating is provided on an interface of
said light-conducting core.
4. Device according to any of the preceding claims, characterized
in that at least one optical grating is embedded in a coating.
5. Device according to any of the preceding claims, characterized
in that at least one optical grating is embedded in said core.
6. Device according to any of the preceding claims, characterized
in that at least one additional optical grating is embedded in said
core for redirecting the orientation of the light.
7. Device according to any of the preceding claims, characterized
in that at least one optical grating is fixed at predetermined
positions.
8. Device according to any of the preceding claims, characterized
in that at least one optical grating is configured in a reversible
design.
9. Device according to any of the preceding claims, characterized
in that at least one optical grating is configured in a reversible
design and is adapted to be activated or deactivated, respectively
by means of a signal or by the supply of energy, respectively.
10. Device according to any of the preceding claims, characterized
in that at least one optical grating is made of liquid
crystals.
11. Device according to any of the preceding claims, characterized
in that said means for coupling comprises or comprise diffusing
centers for redirecting the light by means of diffusion.
12. Device according to any of the preceding claims, characterized
in that at least one zone with diffusing centers is provided in a
coating.
13. Device according to any of the preceding claims, characterized
in that at least one zone with diffusing centers is provided in
said core.
14. Device according to any of the preceding claims, characterized
in that at least one zone with additional diffusion centers is
provided in said core for deflection of the light.
15. Device according to any of the preceding claims, characterized
in that at least one diffusing centre is fixed at predetermined
positions.
16. Device according to any of the preceding claims, characterized
in that at least one diffusing centre is configured as a reversible
design and is adapted to be activated or deactivated, respectively,
by means of a signal or by the supply of energy, respectively.
17. Device according to any of the preceding claims, characterized
in that at least one diffusing centre is made of liquid
crystals.
18. Device according to the introductory clause of claim 1 or any
of the preceding claims, characterized in that said means for
coupling comprise parts or structures having an index of refraction
different from the refractive index of said core, for deflection of
the light by means of refraction.
19. Device according to the introductory clause of claim 1 or any
of the preceding claims, characterized in that at least one recess
is provided in said light-conducting core, which is filled with a
material that presents an index of refraction different from the
refractive index of said core.
20. Device according to any of the preceding claims, characterized
in that at least one zone is provided that presents an index of
refraction different from the refractive index of said core, for
deflection of the light in said core.
21. Device according to any of the preceding claims, characterized
in that at least one coating has reflecting characteristics.
22. Device according to any of the preceding claims, characterized
in that at least one coating presents an index of refraction
different from the refractive index of said core.
23. Method of coupling at least one source for the emission of
light and at least one receiver for receiving light to at least one
preferably planar optical conductor consisting of a
light-conducting core having at least two parallel interfaces in
the regions provided for the conduction of light, which are
provided with coatings resulting in a reflection of the light
guided in the light-conducting core, by employing at least one
means for coupling said source or said receiver, respectively, to
said optical conductor, using at least one optical grating for
redirecting the light by diffraction.
24. Method of coupling at least one source for the emission of
light and at least one receiver for receiving light to at least one
preferably planar optical conductor consisting of a
light-conducting core having at least two parallel interfaces in
the regions provided for the conduction of light, which are
provided with coatings resulting in a reflection of the light
guided in said light-conducting core, by employing at least one
means for coupling said source or said receiver, respectively, to
said optical conductor, using at least one diffusing centre for
redirecting the light by diffusion.
25. Method of coupling at least one source for the emission of
light and at least one receiver for receiving light to at least one
preferably planar optical conductor consisting of a
light-conducting core having at least two parallel interfaces in
the regions provided for the conduction of light, which are
provided with coatings resulting in a reflection of the light
guided in said light-conducting core, by employing at least one
element connected to said light-conducting core, which has an index
of refraction different from the refractive index of said core, for
redirecting the light by refraction.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a device for or a method of
optical signal transfer, respectively. To this end, light is
coupled or decoupled at different sites of a preferably planar
optical conductor.
PRIOR ART
[0002] For the transfer of optical signals over short distances,
frequently optical-fiber cables are also used in other
configurations, in addition to the known light-conducting fibers.
For example, two-dimensional or planar optical-fiber cables have
become known for connecting components or modules. Such
optical-fiber cables are also used in hybrid components or modules,
in combination with electrical conductor structures. This is
particularly expedient because in such a case the electrical
signals can be supplied, on the one hand, which are necessary for
the operation of the active electronic components, and, on the
other hand, a reliable noise-immune and wide-band communication via
the optical-fiber cables becomes possible by optical means.
[0003] For reasons of clarity in the description, the following
statements refer always to the term of "planar optical-fiber
cables". This term does not exclusively refer to complete planar
structures but is rather meant to cover exclusively those regions
of the structures, which are envisaged for light conduction. Hence
this term also encompasses a system composed of several planar
optical conductors that are made of a single piece and comprise
impressions for decoupling between the various light paths. Here,
only the light-conducting zone but no longer the complete structure
is of a planar configuration. Moreover, reference is made to the
German Utility Model DE 200 21 834.4. The essence of this Utility
Model is also meant to constitute part of the present patent
application.
[0004] Such planar optical conductors, to which the present
invention relates, comprise at least one light-conducting core that
comprises at least two parallel interfaces. These interfaces, in
their turn, present coatings that result in a reflection of the
light guided in the light-conducting core. The invention does not
relate to optical conductors without coatings of the core, wherein
this core is surrounded by air, for example, as these optical
conductors are not suitable for reliable application specifically
in densely packed or highly integrated components or modules. It
must be permanently ensured that there is a sufficient distance
from the light-conducting core to the environment. Furthermore, the
light-conducting core is highly sensitive to soiling or mechanical
damage, respectively. The coatings of the parallel interfaces
render the array largely independent of external influences. As a
matter of fact, however, it is also substantially more difficult to
couple and decouple light in such arrangements.
[0005] The German Utility Model DE 90 07 809 describes a
high-precision measuring means including a planar optical-fiber
cable. This measuring means is based, as a matter of fact, on a
principle of direct light conduction without reflections. The
optical-fiber cable serves here to convey the light from a laser
interferometer to an optical detector. In order to allow for the
detection of variations of path lengths in the order of the
wavelength of the light by means of a laser interferometer it is
necessary that the optical path throughout the system be constant
at least in the order of a wave-length of the light or even
fractions thereof. The optical-fiber cable described there is
therefore designed for an indirect propagation of the light coupled
through an optical grating into the optical-fiber cables towards
the receiver. If reflections of the conveyed light would occur on
surfaces in that optical conductor the angle of reflection and
hence the number of reflection events or the optical path,
respectively, would be strongly dependent on the angle of incidence
of the light coupled onto the optical-fiber cable. Then a
high-resolution measurement of the angle could be implemented but a
reliable measurement of the distance could by no means e realized.
By contrast, the invention relates to optical fiber cables in which
several multiple reflections are possible on interfaces of the
light-conducting core. As a result, a far-reaching independence
from the optical angles of the coupling or decoupling elements is
achieved with respect to the core, along with a higher efficiency,
as light, too, can be transmitted at different angles.
[0006] In the known hybrid components or modules, in which
electrical or optical functions are integrated the light is
preferably coupled or decoupled, respectively, on the optical
components such as LEDs, laser diodes or photodiodes become
possible. Specifically in densely packed arrays, it is not possible
to couple the light into the optical conductor on the face ends. In
any case, expensive solutions are required here which operate on
optical or micro-optical elements such as micro lenses, mirrors or
prisms.
[0007] An illustration of the present state of the art can be found
in "Fachverband Elektronik-Design (FED) 2000", Transactions
Electronic Design 2000 & Component Production 2000, pages 110
to 117.
[0008] Moreover, the reference "Multifunctional Grating Couplers
for Bidirectional In-Coupling into Planar Waveguides" by
Bafcklu8nd, Johan, et al., in: IEEE Photonics Technology Letters,
vol. 12, No. 3, March 2000, pages 314 to 316 describes an optical
grating for coupling light into a planar wave guide. His
arrangement, however, is unsuitable for the practical application
in highly integrated systems because in that case the coupling of
light is described exclusively. The problem of light decoupling is
not solved or must take place on face sides of the optical-fiber
cable in correspondence with prior art.
BRIEF DESCRIPTIONS OF THE INVENTION
[0009] Therefore, the problem arises to provide a device or a
method, respectively, for coupling optical components to preferably
planar optical-fiber cables, wherein light decoupling, too, is
possible in addition to light coupling at any sites desired.
[0010] In accordance with the invention, the problem is solved with
the means defined in the independent claims. Expedient improvements
of the invention are the subject matters of the dependent further
claims.
[0011] In correspondence with the invention, a device for the
transfer of optical signals, which comprises at least one optical
conductor, at least one source for the emission of light, at least
one receiver for receiving light and at least one means for
coupling the source and the receiver to the optical conductor, is
designed in such a way that the means for coupling comprises or
comprise optical gratings for redirecting the light by diffraction.
The optical conductor consists of at least one light-conducting
core that includes at least two parallel interfaces provided with
coatings. The core may present any structure desired that is, for
instance, homogeneous, presents a stepped index profile or a
gradient index profile. The light is conducted by reflections of
the light guided in the light-conducting core on the interfaces or
the coatings, respectively. The core, in its turn, is preferably
designed as solid light-conducting body such as glass or Plexiglas.
It may equally consist, however, of a liquid or a gaseous medium.
As used in this document, the terms of the source or the receiver,
respectively, relate generally to light sources or light sinks,
respectively. In the case of sources, for instance, they may be
various emitters in the form of LEDs, laser diodes or even
incandescent lamps. With respect to the receivers, there are not
any limitations so that they may also be photodiodes or even the
human eye, for example. With respect to the inventive device, any
means for conveying light or for guiding or shaping a beam of light
may equally be considered as light source, such as light-conducting
fibers conveying the light from a distant light source to the
inventive device. The essential aspect of the invention is the fact
that light is introduced from the outside (source) and that light
can also be emitted to the outside (receiver).
[0012] In a particularly expedient embodiment of the invention, at
least one optical grating is provided on the outside of a coating.
Such an optical grating permits only the coupling of light into the
light-conducting core only on the outside of a coating. Such an
element, however, can be employed in combination with other
inventive elements for decoupling light with appropriate
elements.
[0013] In a further expedient embodiment of the invention, at least
one optical grating is provided on an interface of the
light-conducting core. Due to such an arrangement on an interface
of the light-conducting core, it is not only possible to couple
light into the light-conducting core but also to decouple the
light. In combination with such embodiments, such a complete
transfer of light between a source and a receiver is possible.
Compared against the arrangement of an optical grating on the
outside of a coating, an arrangement of an optical grating on an
interface of the light-conducting core offers the advantage of
higher sturdiness and reliability because here the optical grating
is additionally protected by a coating above it. Hence any contact
from the outside and soiling are precluded. Moreover, this
embodiment has a lower loss throughout the system than an
arrangement of an optical grating on the outside of a coating. In
the latter case, light orthogonally incident from the outside is
deflected by the optical grating into an oblique angle, which can
be conducted in the core, already on the outside of the coating. In
this configuration, it passes through the coating at a
comparatively flat angle and hence over a comparatively long
distance. As a rule, the coating presents a definitely stronger
attenuation than the core. When the light enters orthogonally
through the coating is deflected only on the surface of the core it
passes through a substantially shorter path distance in the coating
and is hence subjected to a lower attenuation. This creates a
positive effect on the performance balance of the overall transfer
system.
[0014] When the coating contains a material that presents
reflecting properties, in its turn, either the optical grating as
such must be incorporated into this coating, which can be realized,
for instance, in the form of perforations, or a recess must be
provided in the coating at the site of the optical grating.
[0015] An optical grating on the interface of the light-conducting
core can preferably be manufactured in a single operation, together
with the surface of the core. It is possible, for instance, to
impress the optical grating already by means of a die that shapes
the contour of the surface at the same time.
[0016] In another expedient embodiment of the invention, at least
one optical grating is embedded in a coating. With the optical
grating being embedded into the coating, it is possible to achieve,
on the one hand, a mechanical protection of the optical grating
and, on the other hand, also a lower attenuation than that achieved
with an arrangement of the optical grating on the surface of the
coating. Such an arrangement, too, can be expediently manufactured
when the core must be produced in a separate independent process.
Then, the optical grating is applied together with the coating in a
second process step.
[0017] Another embodiment of the invention provides for at least
one optical grating that is embedded into the core. This embedding
into the core permits the manufacture in a single production step
and offers an optimum protection from external influences.
[0018] In a further expedient embodiment of the invention at least
one additional optical grating is embedded into the core for
deflection of the light. In complex light-conducting systems in
particular it may be desirable that the light is guided not only in
a straight direction but also through curves or around curves or
corners, respectively. This is possible with optical gratings for
light deflection in the core. This design equally permits the
implementation of a subdivision of light beams into several partial
beams.
[0019] Another expedient embodiment of the invention consists in
the aspect that at least one optical grating is fixed at
predetermined positions. Such optical gratings are hence
manufactured already by the manufacturing process at defined
predetermined positions. They excel themselves by a high mechanical
stability and sturdiness.
[0020] In a further expedient embodiment of the invention, at least
one optical grating has a reversible design. Depending on the
requirements and demands on the instantaneous operating condition,
such a reversible optical grating can be activated or deactivated.
If the optical grating is activated at a defined site coupling or
decoupling is possible at this site; if the optical grating is
deactivated coupling or decoupling is no longer possible. Hence,
the distribution of the light from various emitters to various
receivers may be controlled. When a reversible optical grating is
integrated into the core for light deflection the direction of the
light or the distribution of the beam can be controlled by the
optical grating as well. As far as the reversible optical grating
is concerned reference is made to the international publication WO
99/04309 whose essence is also incorporated as an element into the
present patent application.
[0021] A further expedient configuration consists in the provision
that at least one reversible optical grating can be activated or
deactivated by means of a signal or by the supply of energy,
respectively. As a result, controllable optical gratings are
achieved that may be used to implement an active control of the
optical signal flow. Hence, the supply of light to or from defined
receivers or emitters, respectively, can be controlled.
[0022] In another expedient embodiment of the invention, at least
one optical grating consists of liquid crystals. Liquid crystals
permit the implementation of controllable or reversible optical
gratings in a particularly simple manner.
[0023] Another expedient configuration of the invention consists in
the provision that the means for coupling comprise diffusing
centers for light deflection by means of diffusion. Various types
of the diffusing centers such as particles of a different material
or zones of a different state of the core material, e.g. in a
different crystal structure, or of a different state of matter,
e.g. in the form of small gas bubbles in a liquid, are suitable for
diffusing the light. As far as the configuration by means of
diffusing centers reference is also made to the preceding
description of the optical gratings.
[0024] Another expedient embodiment of the invention consists in
the aspect that at least one zone with diffusing centers is
provided in a coating. This permits a particularly simple
manufacture.
[0025] In a further expedient embodiment of the invention, at least
one zone with diffusing centers is provided in the core. This
provision allows for particularly efficient coupling.
[0026] Another expedient embodiment of the invention provides for a
zone with additional diffusing centers for deflection of the light
in the core.
[0027] A further expedient embodiment of the invention provides for
at least one diffusing center fixed at a predetermined
position.
[0028] In another particularly expedient embodiment of the
invention, at least one diffusing center is of a reversible design
and can be activated or deactivated, respectively, by means of a
signal or by the supply of energy.
[0029] In a further expedient embodiment of the invention, at least
one diffusing center is made of liquid crystals. In this case, the
orientation of the liquid crystals and hence the diffusion effect
can be controlled in a particularly simple manner.
[0030] In another particularly expedient embodiment of the
invention, the means for coupling encompass elements or structures
presenting an index of refraction different from the refractive
index of the core for deflecting the light by refraction. As far as
the configuration by means of different indices of refraction is
concerned reference is also made to the description of the optical
gratings or the diffusing centers, respectively, which is set out
above.
[0031] Another expedient embodiment of the invention provides for
at least one recess in the light-conducting core, which is filled
with a material that has an index of refraction different from the
refractive index of the core. This results in on orientation at the
junction between the core and the material. The material having a
different index of refraction may be a solid, a liquid or even a
gaseous material. It may also be a material whose index of
refraction varies in response to electrical signals or the supply
of energy, respectively.
[0032] Another expedient embodiment of the invention provides for
at least one zone having an index of refraction different from the
refractive index of the core for the deflection of the light in the
core. In this manner, it is possible to implement control of the
light or of the orientation within the core.
[0033] In another embodiment of the invention, at least one coating
presents reflecting characteristics. Hence, a reflection on the
coating material is used to guide the light in the core.
[0034] A further embodiment of the invention comprises at least one
coating that has an index of refraction different from the
refractive index of the core. This provision permits the conduction
of the light in the core by total reflection of the light on the
interface between the core and the coating. In the case of a core
made of a synthetic resin, for example, the coating may consist of
a different synthetic resin having a different index of refraction.
The coating may, of course, also present a gradient profile of the
index of refraction.
[0035] An inventive method serves to couple at least one source for
the emission of light and at least one receiver for receiving light
to at least one preferably planar optical conductor. This optical
conductor comprises a light-conducting core having at least two
parallel interfaces in the regions provided for the conduction of
light, which are provided with coatings resulting in a reflection
of the light guided in the light-conducting core. Here, coupling is
realized by at least one means for coupling the source or the
receiver, respectively to the optical conductor, with at least one
optical grating being employed for redirecting the light by
diffraction.
[0036] Another method serves to couple at least one source for the
emission of light and at least one receiver for receiving light to
at least one preferably planar optical conductor. There, this
optical conductor comprises a light-conducting core having at least
two parallel interfaces in the regions provided for the conduction
of light, which are provided with coatings resulting in a
reflection of the light guided in the light-conducting core.
Coupling is realized by at least one means for coupling the source
or the receiver, respectively, to the optical conductor, using at
least one diffusing center for redirecting the light by
diffusion.
[0037] A further inventive method serves to couple at least one
source for the emission of light and at least one receiver for
receiving light to at least one preferably planar optical
conductor. There, this optical conductor comprises a
light-conducting core that has at least two parallel interfaces in
the regions provided for the conduction of light, which are
provided with coatings resulting in a reflection of the light
guided in the light-conducting core. Here, Coupling is realized by
at least one means for coupling the source or the receiver,
respectively, to the optical conductor, using at least one element
connected to the light-conducting core, which has an index of
refraction different from the refractive index of the core, for
redirecting the light by refraction.
DESCRIPTION OF THE DRAWINGS
[0038] In the following, the invention will be described by
exemplary embodiments, without any restriction of the general
inventive idea, with reference to the drawings.
[0039] FIG. 1 shows a preferred embodiment of the invention in the
form of a hybrid printed-circuit board.
[0040] FIG. 2 is an exemplary view of one embodiment of the
invention, which comprises diffusing centers or an optical grating
structure for coupling light.
[0041] FIG. 3 illustrates an exemplary embodiment of the invention,
which comprises an optical grating structure on the
light-conducting core.
[0042] FIG. 1 shows a longitudinal section taken through an
electro-optical printed-circuit board in hybrid design, which
includes two electrical layers (1) between which an optical layer
(2) is sandwiched. The latter comprises a light-conducting core (4)
that is enclosed by two parallel coatings (3) on the interfaces.
For coupling light by means of a light source (3), a discontinuity
(5) is provided in the conductive layer. It is equally possible to
use a conductive material having permeable characteristics for the
wavelength used to transfer the light. In this case, a
discontinuity is not required in this conductive layer.
[0043] At the position of the discontinuity (5), a means is
provided for coupling the light. This means may optionally comprise
an optical grating, diffusing centers or a material having a
different index of refraction.
[0044] FIG. 2 shows a schematic view of the process of coupling
light through diffusing centers or optical gratings, respectively.
In part (a), a process of coupling by means of diffusing centers
(7) is shown, which is provided in the core. Light is incident on
these diffusing centers and is deflected into different directions.
One part of the light is deflected at angles that permit a
conduction of light within the core. The further conduction of
light is realized by reflection on the interfaces of the core with
the coating. Part (b) illustrates the process of coupling by means
of an optical grating (8). There, incident light is deflected by
diffraction on the optical grating at angles that may be conducted
within the core. This configuration does not allow for light
decoupling by means of the optical grating because the light, which
is guided within the core, does not reach the optical grating
because it is reflected before on the interface with the coating.
When the optical grating is now provided don the outside of the
core, rather than on the outside of the coating, as is illustrated
in FIG. 2(b), the light that is guided in the core may be incident
on this optical grating, too, and may undergo a corresponding
deflection. In this manner, it is also possible to decouple
light.
[0045] FIG. 3 shows an exemplary configuration of the invention,
which comprises a grating structure on the light-conducting
core.
[0046] The light-conducting core (4) is provided with coatings (3)
on its parallel interfaces. An optical grating (8) for diffraction
of the light is applied directly on an interface of the core. Light
(9), which propagates in the light-conducting core and is incident
on the optical grating, may now be deflected into regions outside
the light-conducting core. This is detected, for instance, by means
of a receiver (10).
* * * * *