CA2335045A1 - Optical coupling element - Google Patents
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- CA2335045A1 CA2335045A1 CA002335045A CA2335045A CA2335045A1 CA 2335045 A1 CA2335045 A1 CA 2335045A1 CA 002335045 A CA002335045 A CA 002335045A CA 2335045 A CA2335045 A CA 2335045A CA 2335045 A1 CA2335045 A1 CA 2335045A1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/30—Optical coupling means for use between fibre and thin-film device
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- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Couplings Of Light Guides (AREA)
- Optical Integrated Circuits (AREA)
- Mechanical Coupling Of Light Guides (AREA)
Abstract
The invention relates to an optical coupling element (20) comprising at leas t one guide groove (22) for an optical wave guide and a respective guide groov e (21) for an optical fibre. In order to provide a coupling element that is ea sy to produce, whereby a structure is provided in the coupling area that does n ot impair the coupling and the optical fibre core material and the embedding material for the optical fibre can be chosen independently of each other, a connecting member (23) made from a waveguide sheath material is arranged in the coupling area between the guide groove (22) of the optical wave guide an d the guide groove (21) of the optical fibre.
Description
Optical coupling element Description The invention relates to an optical coupling element that is manufactured in one piece molding technology using polymer waveguide cladding material, with at least one guide groove each for an optical waveguide and an optical fiber.
Coupling elements of this type can be used, for example, in optical communications technology or in sensor systems.
The transmission of signals and data in communications systems and in sensor systems is increasingly being done on an optical basis. Instead of electrical connections, optical waveguides are used to establish optical connections which, when properly configured, form an optical network. To construct such a network, a number of different components are required in large numbers and at the lowest possible prices.
These components include, for example, plugs and splices, signal splitters and signal branches, wavelength division multiplexers (WDM) and switches.
Optical waveguides are composed of a waveguide core and a waveguide cladding and are generally made of glass or plastic. The transport of the optical signal thereby takes place essentially in the core of the optical waveguide. One or more optical modes are guided, depending on the transmission wavelength and size or refractive index of the optical waveguide. In particular in the sensor system sector and for the transmission of data over long-distances, a single-mode transmission is used, which requires the use of single-mode optical waveguides. Single-mode optical waveguides of this type, at the common wavelengths (0.4 - 1.6 Nm), have core diameters in the range of 2 - 10 pm.
On account of the small core dimensions, particularly strict requirements are set for the connections of single-mode optical waveguides with each other or with optical components. For applications in optical communications technology, it is thereby necessary for the position of the fibers to maintain an accuracy of ~ 1 Nm in the lateral direction and ~ 0.5° for the angular orientation. Such tolerances can be achieved, for fiber ribbon plugs, for example, which are flat cables that have a plurality of optical waveguides, by manufacturing the plug with positioning structures for the optical waveguides using the injection molding method and a high-precision mold manufactured using micro circuitry techniques (H.-D. Bauer, L. Weber, W.
Ehrfeld:
"LIGA for Applications for Fibre Optics: High Precision Fibre Ribbon Ferrule", MST
News 10 (1994), p. 18-19].
Integrated optical components are increasingly being used for the passive and active processing of optical signals. For this purpose, an optical waveguide system is integrated into a substrate that performs a specific function (signal branching, switching etc.). Optical waveguides can be coupled to the component while staying within the above referenced tolerances, for example, by an active or semi-active assembly process of the components in which the position of the fibers is varied as a function of the measurement of the incident light and the light measured at the output, and thereby optimized to a minimal loss. The cost and complexity of such a manufacturing process are relatively high.
W
A very economical solution for the manufacture of such components lies in the use of polymer materials that are processed in a molding process such as injection molding, injection stamping, hot stamping, reaction molding etc. In this context, it is particularly advantageous, in addition to the wave-conducting areas, to also integrate fiber guide areas into the component, in which the fibers need only be inserted, without any need for further adjustment. Such a fiber coupling is also called a self-adjusting or passive fiber-chip coupling.
The use of LIGA technology is particularly favorable for the manufacture of the components. This technology includes the three process steps lithography, electroplating and molding. In the first step, a resist is deposited on a substrate and printed through a suitable mask, e.g. with synchrotron radiation. After the development, galvanic metal is deposited in the areas removed from the resist, as a result of which a mold insert is formed as a negative of the original structure. This mold insert is used in a molding process (e.g. injection molding) for the manufacture of moldings, e.g.
moldings made of plastic. Using LIGA technology, moldings can be manufactured with a very high precision (< 1 Nm). A detailed description of the LIGA technology is presented, among other places, in: W. Ehrfeld, M. Abraham, U. Ehrfeld, M. Lacher, H.
Lehr:
"Materials for LIGA products", Micro-Electrical Mechanical Systems: An investigation of microstructures, sensors, actuators, ... / edited by W. Benechcke, published by The Institute of Electrical and Electronic Engineers, Piscataway, NJ; IEEE Press, 1994.
In addition to a high coupling efficiency, an additional requirement is generally that the reflection loss must be as high (sic - low?] as possible. In other words, the smallest possible fraction of the light must be reflected back into the incoming fiber.
Such a reflection must be avoided because it interferes with the transmissian laser and thus can lead to a higher noise level. The value for the reflection loss to be achieved for applications in the telecommunications sector is less than -55 dB. (see Bellcore:
"Generic Requirements for Fibre Optic Branching Components, GR1209, ISSUE 1.
November 1994"; Belcore, Morristown, 1994).
DE 42 12 208 describes a method for the manufacture of optical polymer components, in which a microstructure body is manufactured using Si-micromechanics and excimer laser processing. From this microstructure body, by galvano forming, a mold insert is produced which is used for molding with a polymer material. The microstructure body thereby has a V-shaped fiber receptacle and a groove for the waveguides.
US 5,343,544 describes an integrated optical fiber coupler that consists of a substrate with fiber positioning grooves and possibly channels. The optical fibers and the optical waveguides are separated from each other by a groove that is filled with core material of the optical waveguide. This coupling element can be manufactured using a mold that has been galvanically formed from a master.
DE 42 08 278 A1 describes an integrated optical component. In this integrated optical component that comprises a silicon substrate, the glass fibers run in an etched, V-shaped groove. The extraction of the light waves is performed by an optical waveguide made of an optical polymer by pulse coupling. If the cross section surface of the optical waveguide is very much smaller than the cross section surface of the glass fibers, the prior art patent teaches that a second optical waveguide is located between the glass fiber and the first optical waveguide. In that case, the second optical waveguide has a slightly lower refractive index than the first optical waveguide.
WO 99167667 5 PCTlEP99104298 US 4,865,407 describes a coupling element made of lithium niobate. This material is difficult to process and cannot be used for economical mass production. On the lithium niobate substrate, a thin titanium film is deposited, lithographically structured and thermally diffused into the substrate material. On the end opposite the fiber end, the film thickness is varied so that the refractive index of the resulting waveguide decreases gradually. As a result of the decreasing refraction index, the light guided in the waveguide is deflected into the substrate material and focused. The boundary surface of the fiber receptacle structure lies in the area of the focus. Because the light is deflected into the substrate material, the fiber core must lie lower than the waveguide.
An additional disadvantage is that the boundary surface is not realized vertically with respect to the axis of the fiber, but is inclined so that it can receive the diagonally incident light emitted from the waveguide. The fiber end is also correspondingly cut at an angle. One significant disadvantage of this arrangement is that such a diagonal boundary surface, which has an undercut, cannot be manufactured using molding techniques, but requires complex, time-consuming and expensive precision machining operations. Likewise, the beveling of the end of the fiber is a complex, time-consuming and expensive step.
EP 0 560 043 B1 describes passive integrated optical components with a molding made of polymer material that have optical waveguide structures and fiber guide structures. In this case, the grooves are rectangular grooves, into which the fibers are inserted into the grooves and optical waveguide core material is introduced. As a result of the different diameters of the optical waveguide and the optical fibers, the grooves have different depths. Consequently, at the point of contact where the end of the fiber meets the optical waveguide, there must be a step. Similar stepped structures are described in "Precision components for optical fibre connections fabricated by the LIGA
process", by Arnd Rogner, SPIE., Vol. 1973, pp. 94-100, and EP 0 324 492. Web-like structures are WO 99!67667 6 PCTIEP99104298 used only where exclusively waveguide structures are connected to each other.
The manufacturing methods generally provide that a substrate is provided with a step, the height of which can be precisely achieved, for example, by diamond milling. Then the stepped substrate is provided with a resist. During the subsequent synchrotron irradiation, a mask is used, the waveguide area and fiber area of which each have the shape of a rectangular aperture This mask is oriented with respect to the step of the substrate so that the fiber area and the waveguide area on the mask overlap with the later fiber area and the waveguide area on the coated substrate That means that the transition from the fiber area and the waveguide area of the mask must lie on the step, which requires a complex positioning of the mask. In the next step, the printing and development of the resist are done using galvano forming; a mold insert is manufactured which forms the negative. The mold insert is molded to create the final molding by means of hot stamping or injection molding. This molding has the corresponding groove, into which the optical fiber is inserted or into which the waveguide material is cast.
A disadvantage of this manufacturing process is that the step must be realized with great precision. In particular, the substrate may not have any burrs on the edge of the step, because the burr represents an undercut and can lead to disruptions during the galvano forming and the molding. In this case, the proper function of the coupling of optical waveguides and optical fibers can no longer be performed. Depending on the manufacturing technique used for the substrate and the step, such a burr can be avoided only with a relatively great deal of effort and expense. For example, the burr always occurs during fly-cut milling if the cut of the milling cutter runs from the area of the step over the edge.
.r'.
An additional disadvantage of such a groove structure is that during the filling of the waveguide core material into the optical waveguide structure, the material can flow into the guide structure for the glass fiber, so that the fiber embedding material and the waveguide core material cannot be selected independently of each other.
Finally, the fibers must be provided with a diagonal terminal surface to minimize reflections.
The object of the invention is to create a coupling element that is easy to manufacture, has a structure in the coupling area that does not adversely affect the coupling, and in which the optical waveguide material and embedding material can be selected independently of each other.
The invention teaches a coupling device in which a web made of waveguide cladding material is located as an integral component of the coupling element in the coupling area between the guide groove of the optical waveguide and the guide groove of the optical fiber.
The starting point for the invention was the knowledge that optical fibers and optical waveguides cannot be connected to each other directly, but must be offset by some distance from each other in the axial direction. It was discovered that in contrast to a lateral offset or an angular error, an axial offset has only a slight effect on the coupling loss. One surprising feature of this discovery was that this low caupling loss could be achieved in both single-mode and multi-mode technology if the dimensions and refractive indices of the optical waveguide are appropriately selected.
Because the optical fibers and the optical waveguides do not abut each other directly, but are separated from each other by a web, during the manufacturing process, the v z critical edge of the stepped substrate, e.g. the above-mentioned burr, is covered by the web, as a result of which a significantly simpler manufacturing process becomes possible.
The separation of the optical waveguide and the optical fiber by the web also offers greater flexibility in the selection of the waveguide core material and the embedding material for the optical fiber For example, in couplers of the prior art, the embedding material had to be the same as the waveguide core material. As a result, a reflection occurs at the boundary surface between the optical fiber and its embedding material, so that the reflected portion must be deflected by a relatively complex diagonal cutting of the optical fiber.
With the coupling element claimed by the invention, the embedding material can be selected so that the refractive index need only be appropriately the same as that of the fiber core material. Any remaining reflection at the boundary surface between the fiber embedding material and the web (waveguide cladding material) can be deflected by a diagonally cut surface of the web.
The web thus has the advantage, among other things, that one or both surfaces of the web can have a structure which makes it unnecessary to process the extremity of the optical fiber, for example.
An additional advantage that results from the use of two different materials is that the fiber embedding material can be selected in terms of its adhesive and strength properties, and the waveguide core material in terms of its optical transparency. Any penetration of the materials in question into the other guide groove is prevented by the web.
WQ 99/67667 9 PCTlEP99104298 The surface of the web (light entry surface) facing the guide groove of the optical fiber preferably has an inclined diagonal surface that encloses an angle cp of between 2° and 10° with a line perpendicular to the longitudinal axis of said guide groove. The perpendicular line preferably lies in the plane of the optical coupling element, so that the inclined surface can be seen in an overhead view of the coupling element. The width and height of the inclined surface are preferably equal to or greater than the diameter of the core of the optical fiber that the inclined surface faces. The reflection back into the optical fiber is eliminated by the selection of an appropriate angle for the inclined surface. Thus there is no need to bevel the terminal surface of the optical fiber.
Independently of or in addition to the configuration of the light entry surface, the surface of the web (light exit surface) that faces the guide groove of the optical waveguide can form an angle ~ of between 0.1 ° and 2° with a line perpendicular to the longitudinal axis of the guide groove of the optical fiber. That means that the two longitudinal axes of the guide grooves of the optical fiber and the optical waveguide also enclose the angle ~.
This configuration leads to a bent arrangement, whereby the angle ~ is set to the angle cp, taking into consideration the refractive indexes of the materials used, thereby achieving an optimal coupling efficiency.
The guide structure for the optical waveguide is advantageously widened toward the light exit surface, so that it becomes possible to transmit the light cone realized by the web completely into the core of the optical waveguide.
In an additional realization, there can be a plurality of guide grooves for optical waveguides and optical fibers next to one another. In this embodiment, there is a common web at a right angle to the guide grooves, whereby both the guide grooves for v z WQ 99!67667 10 PCTIEP99104298 the optical fibers and the guide grooves for the optical waveguides are connected to one another by means of at least one transverse groove that is oriented parallel to the web. Such transverse grooves increase the stability and mechanical strength of the mold insert used during the manufacture and are used to limit shrinkage during the molding.
The guide grooves for the optical waveguide or waveguides as well as the guide grooves for the optical fiber or fibers and the web are preferably fabricated in one piece from polymer material using molding processes.
The invention teaches that it is advantageous to select the web thickness less than 100 Nm, and preferably less than 50 pm.
The invention is explained in greater detail below with reference to the exemplary embodiments illustrated in the accompanying drawings.
Figure 1 is a view of the coupling element in perspective, Figure 2 is a view, in perspective, of a substrate with resist and mask for the printing, Figure 3 is an overhead view of the coupling element illustrated in Figure 1 to show the beam path, Figure 4 is a view in perspective of an additional embodiment of a coupling element, and Figures 5a are a sketch and a diagram respectively to explain the reflection loss as a and 5b function of the axial offset.
Figure 1 shows a coupling element 20 with guide grooves in the farm of a fiber groove 21 and a waveguide groove 22. The fiber grooves 21 and waveguide grooves 22 are not directly in contact with each other, but are separated from each other by a web 23.
The width of the web zs (See Figure 5a) is in the range of 5 - 100 Nm. The waveguide grooves 22 widen in the direction of the web 23, which is designated the taper 25, as a result of which the optical field that widens as it passes through the web 23 can be better received by the waveguide core, which is also explained in greater detail with reference to Figure 3.
The web 23, on its surface 40 (light entry surface) facing the fiber groove 21, has an inclined surface 24, which is inclined, for example, at an angle of cp =
8° with respect to the line 60 (See Figure 3) perpendicular to the longitudinal axis 61 of the fiber guide structure. As illustrated in Figure 3, the total light entry surface is formed by the inclined surface 24. The inclined surface 24 is inclined in the horizontal direction and extends over the entire depth of the groove 21. As a result of this inclined surface 24, light reflected by the light entry surface 40 does not run back into the optical fiber. This feature is particularly advantageous if the refractive index of the material used to embed the optical fiber is approximately equal to that of the core material of the optical fibers.
The coupling element 20 is preferably manufactured by means of a combination of LIGA and precision machining operations, and is described below with respect to the manufacture of a coupling between a standard single-mode fiber (fiber diameter pm, fiber core diameter approximately 8 Nm) and a square single-mode waveguide with an edge length 8 Nm, in conjunction with Figure 2. The starting point for the manufacture is the substrate 1 with a step 4, the height of which is very precisely set, for example, by diamond milling cutters to ho = 58.5 ~ 1 Nm. Then this substrate is coated with resist 3 and the height of the resist is thereby adjusted by polishing so that r~.
WO 99167667 12 PCTlEP99/04298 in the low fiber area 5 it is h2 = 66.5 pm and in the flat waveguide area 7 h~
= 8 Nm.
During the subsequent synchrotron irradiation, a mask 6 is used which has a waveguide area 9 and a fiber area 8 which are separated from each other by a web 28. The mask has structures for waveguide grooves 27 in the form of a rectangular opening with d~ _ 8 pm and for fiber grooves 26 in the form of a rectangular opening with d2 =
125 Nm.
This mask is oriented with respect to the substrate step 4 so that the fiber area 8 and the waveguide area 9 on the mask 6 coincide with the fiber area 5 and the waveguide area 7 on the coated substrate. The next step is the irradiation and development of the resist, as a result of which fiber grooves 21' and waveguide grooves 22' are formed, which are separated from one another by the web 23'. One advantage achieved by the formation of the web 23' is that the burr 9 that is inevitably formed during the manufacture falls on the step 4 of the substrate 1 in the area of the web 23', and is thus completely covered by the resist 3. In this case, the end of the fiber groove 21' is the image of the absorber structure provided on the mask 6, and does not result from the lateral surface 2 of the substrate step 4. The manufacturing process is thereby significantly simplified, and manufacturing-related problems on the substrate 1 cannot influence the coupling of the optical fibers and optical waveguides. As is known from LIGA technology, the next step is the manufacture of a mold insert by the galvano forming and its molding by hot stamping or injection molding. The optical fiber is then inserted into the fiber groove 21 of the coupling element 20 (See Figure 1 ), and the waveguide material is introduced into the waveguide grooves 22.
Using this manufacturing process, an accuracy of the orientation of the waveguide groove 22 with respect to the fiber grooves 21 of less than 1 Nm can be achieved.
Figure 3 illustrates the optical function of the coupling in detail. In the coupling element 20, the figure shows the fiber cladding material 35, the fiber core 36, the waveguide cladding material 37 and the waveguide core 38. The entire coupling element 20 is made of waveguide cladding material. The end of the waveguide facing the web widens in the form of the taper 38b. The inclined surface 24 of the web 23 is also in front of the fiber end surface 42. The space between the fiber end and the inclined surface 24 is filled with a fiber embedding material 41. Exiting from the fiber core 36 is the light cone 39 which is refracted on the beveled surface 24 and then widens. This light cone is completely received by the waveguide 38 that widens an the front end. The adjacent taper 38b causes the field to be transformed back to its original width.
In accordance with Snell's law of refraction, the magnitude of the refractive angle ~ is a function of the angle cp and of the refractive indexes of the fiber embedding material and waveguide material. It is particularly advantageous to orient the waveguide core 38 at an angle so that its longitudinal axis 62 coincides with that of the refracted light cone 39.
That means that the light exit surface 44 of the web 23 facing the waveguide 38 is also oriented at an angle. In this manner, an optimal coupling efficiency is achieved.
With regard to the intensity of the reflection, it is important that the light from the fiber core 36 to the waveguide 38 passes a plurality of boundary surfaces. These surfaces, in order, are the boundary surface (fiber end surface 42) between the fiber core 36 and fiber embedding material 41, the inclined boundary surface 43 between the fiber embedding material 41 and the waveguide cladding 37, and the boundary surface (light exit surface 44) between the waveguide cladding 37 and the waveguide core 38.
Theoretically, the reflection on the individual boundary surfaces is greater, the greater the difference between the refractive indexes on both sides of the boundary surface.
WO 99167667 14 PCTlEP99/04298 Because the materials for the waveguide cladding 37 and core 38 are generally selected on the basis of their optical transparency and their processing characteristics, their refractive indexes are already defined. A typical material for the waveguide cladding, for example, is PMMA, which has a refractive index of 1.49, which differs significantly from the refractive index of the optical fiber cladding, which is 1.45. It is particularly advantageous to use a material for the fiber embedding material 41 that is different from the material used for the waveguide core 38 and advantageously has the same refractive index as the fiber core 36. Consequently, practically no backward reflections will occur on the corresponding boundary surface (fiber end surface) 42. The same is true for the light exit surface 44, because the refractive indexes of the waveguide core and waveguide cladding are generally close to each other. The principal portion of the reflection therefore occurs on the boundary surface 43 and the light cone 45 is formed. The light cone is inclined by the angle 2cp as a function of the law of reflection with respect to the fiber end surface. In that case, it is particularly advantageous to select the angle cp large enough (e.g. cp = 4°), so that the light reflected back can no longer be received by the fiber core and therefore there is no reflection back into the optical fiber.
An additional advantageous configuration of the invention is illustrated in Figure 4. The coupling element 30, which is shown in perspective, has a plurality of fiber grooves that lye next to one another, of which the fiber grooves 21 and 31 are visible. The two fiber grooves 21 and 31 are connected to each other by a groove 32 that runs in the transverse direction. The same is true for the waveguide grooves 22 and 33 that lie next to each other and are connected to each other by the likewise transverse groove 34.
This configuration has the advantage that it significantly simplifies assembly, because the core material, when it is introduced into the guide structure, can be distributed more effectively and thereby reduces the risk of unfilled spaces. This advantage becomes particularly important when two different materials are used for the waveguide core and to embed the optical fibers. An additional advantage is that as a result of the transverse W z W,O 99/67667 15 PCT/EP99104298 grooves 32 and 34, a higher stability and mechanical strength of the mold insert is achieved, and that the transverse grooves 32 and 34 limit shrinkage during the molding process.
Figures 5a and 5b show the fiber waveguide coupling losses as a function of the axial offset zS. The geometry on which the calculation is based is illustrated in Figure 5a.
Optical fibers 46 with fiber core 47 and wavve guides with cladding 48 and core 49 are separated from each other by the distance zs. Between the fiber and waveguide end lies the waveguide cladding material 50 which has the refractive index 1.49. The results are calculated in Figure 5b for three typical applications.
(i) shows the coupling of a square step index waveguide with an edge length of 55 Nm and a numerical aperture of 0.219 into a gradient index fiber with a core diameter of 62.5 Nm and a numerical aperture of 0.275.
(ii) shows the coupling in the reverse direction, i.e. from the gradient index fiber into the waveguide. In both cases, the calculations were based on a wavelength of 850 mm, which is typically used for multi-mode systems in the field of short-distance connections.
The increase in the loss in both cases is slow, and for zs = 100 Nm, for example, is less than 2.5 dB.
(iii) shows the coupling of a single-mode fiber with a core diameter of 9 Nm and a numerical aperture of 0.1 into a square step index waveguide with a core diameter of 8 Nm and a numerical aperture of 0.1. For the coupling in the reverse direction, we get the same result. The calculation was based on a wavelength of 1300 nm, which is WO 99!67667 16 PCTIEP99104298 typically used in the field of telecommunications for long-distance connections. The loss increases slowly, and for zs = 100 Nm, for example, is less than 0.75 dB.
Nomenclature 1 Substrate 2 Lateral surface 3 Resist 4 Step Fiber area (substrate) 6 Mask 7 Waveguide area (substrate) 8 Fiber area (mask) 9 Waveguide area (mask) 20 Coupling element 21 Fiber groove 21' Fiber groove 22 Waveguide groove 22' Waveguide groove 23 Web 23" Web 24 Diagonal surface 25 Taper 26 Fiber groove structure 27 Optical waveguide structure 28 Web 29 Burr 30 Coupling element 31 Fiber groove 32 Transverse groove 33 Waveguide groove 34 Transverse groove 35 Fiber cladding 36 Fiber core 37 Waveguide cladding 38 Waveguide core 38b Taper 39 Light cone 40 Light entry surface 41 Fiber embedding material 42 Fiber end surface 43 Boundary surface 44 Light exit surface 45 Light cone 46 Optical fiber 47 Fiber core 48 Optical waveguide cladding 49 Optical waveguide core 50 Optical waveguide cladding material 60 Perpendicular line 61 Longitudinal axis 62 Longitudinal axis _.
Coupling elements of this type can be used, for example, in optical communications technology or in sensor systems.
The transmission of signals and data in communications systems and in sensor systems is increasingly being done on an optical basis. Instead of electrical connections, optical waveguides are used to establish optical connections which, when properly configured, form an optical network. To construct such a network, a number of different components are required in large numbers and at the lowest possible prices.
These components include, for example, plugs and splices, signal splitters and signal branches, wavelength division multiplexers (WDM) and switches.
Optical waveguides are composed of a waveguide core and a waveguide cladding and are generally made of glass or plastic. The transport of the optical signal thereby takes place essentially in the core of the optical waveguide. One or more optical modes are guided, depending on the transmission wavelength and size or refractive index of the optical waveguide. In particular in the sensor system sector and for the transmission of data over long-distances, a single-mode transmission is used, which requires the use of single-mode optical waveguides. Single-mode optical waveguides of this type, at the common wavelengths (0.4 - 1.6 Nm), have core diameters in the range of 2 - 10 pm.
On account of the small core dimensions, particularly strict requirements are set for the connections of single-mode optical waveguides with each other or with optical components. For applications in optical communications technology, it is thereby necessary for the position of the fibers to maintain an accuracy of ~ 1 Nm in the lateral direction and ~ 0.5° for the angular orientation. Such tolerances can be achieved, for fiber ribbon plugs, for example, which are flat cables that have a plurality of optical waveguides, by manufacturing the plug with positioning structures for the optical waveguides using the injection molding method and a high-precision mold manufactured using micro circuitry techniques (H.-D. Bauer, L. Weber, W.
Ehrfeld:
"LIGA for Applications for Fibre Optics: High Precision Fibre Ribbon Ferrule", MST
News 10 (1994), p. 18-19].
Integrated optical components are increasingly being used for the passive and active processing of optical signals. For this purpose, an optical waveguide system is integrated into a substrate that performs a specific function (signal branching, switching etc.). Optical waveguides can be coupled to the component while staying within the above referenced tolerances, for example, by an active or semi-active assembly process of the components in which the position of the fibers is varied as a function of the measurement of the incident light and the light measured at the output, and thereby optimized to a minimal loss. The cost and complexity of such a manufacturing process are relatively high.
W
A very economical solution for the manufacture of such components lies in the use of polymer materials that are processed in a molding process such as injection molding, injection stamping, hot stamping, reaction molding etc. In this context, it is particularly advantageous, in addition to the wave-conducting areas, to also integrate fiber guide areas into the component, in which the fibers need only be inserted, without any need for further adjustment. Such a fiber coupling is also called a self-adjusting or passive fiber-chip coupling.
The use of LIGA technology is particularly favorable for the manufacture of the components. This technology includes the three process steps lithography, electroplating and molding. In the first step, a resist is deposited on a substrate and printed through a suitable mask, e.g. with synchrotron radiation. After the development, galvanic metal is deposited in the areas removed from the resist, as a result of which a mold insert is formed as a negative of the original structure. This mold insert is used in a molding process (e.g. injection molding) for the manufacture of moldings, e.g.
moldings made of plastic. Using LIGA technology, moldings can be manufactured with a very high precision (< 1 Nm). A detailed description of the LIGA technology is presented, among other places, in: W. Ehrfeld, M. Abraham, U. Ehrfeld, M. Lacher, H.
Lehr:
"Materials for LIGA products", Micro-Electrical Mechanical Systems: An investigation of microstructures, sensors, actuators, ... / edited by W. Benechcke, published by The Institute of Electrical and Electronic Engineers, Piscataway, NJ; IEEE Press, 1994.
In addition to a high coupling efficiency, an additional requirement is generally that the reflection loss must be as high (sic - low?] as possible. In other words, the smallest possible fraction of the light must be reflected back into the incoming fiber.
Such a reflection must be avoided because it interferes with the transmissian laser and thus can lead to a higher noise level. The value for the reflection loss to be achieved for applications in the telecommunications sector is less than -55 dB. (see Bellcore:
"Generic Requirements for Fibre Optic Branching Components, GR1209, ISSUE 1.
November 1994"; Belcore, Morristown, 1994).
DE 42 12 208 describes a method for the manufacture of optical polymer components, in which a microstructure body is manufactured using Si-micromechanics and excimer laser processing. From this microstructure body, by galvano forming, a mold insert is produced which is used for molding with a polymer material. The microstructure body thereby has a V-shaped fiber receptacle and a groove for the waveguides.
US 5,343,544 describes an integrated optical fiber coupler that consists of a substrate with fiber positioning grooves and possibly channels. The optical fibers and the optical waveguides are separated from each other by a groove that is filled with core material of the optical waveguide. This coupling element can be manufactured using a mold that has been galvanically formed from a master.
DE 42 08 278 A1 describes an integrated optical component. In this integrated optical component that comprises a silicon substrate, the glass fibers run in an etched, V-shaped groove. The extraction of the light waves is performed by an optical waveguide made of an optical polymer by pulse coupling. If the cross section surface of the optical waveguide is very much smaller than the cross section surface of the glass fibers, the prior art patent teaches that a second optical waveguide is located between the glass fiber and the first optical waveguide. In that case, the second optical waveguide has a slightly lower refractive index than the first optical waveguide.
WO 99167667 5 PCTlEP99104298 US 4,865,407 describes a coupling element made of lithium niobate. This material is difficult to process and cannot be used for economical mass production. On the lithium niobate substrate, a thin titanium film is deposited, lithographically structured and thermally diffused into the substrate material. On the end opposite the fiber end, the film thickness is varied so that the refractive index of the resulting waveguide decreases gradually. As a result of the decreasing refraction index, the light guided in the waveguide is deflected into the substrate material and focused. The boundary surface of the fiber receptacle structure lies in the area of the focus. Because the light is deflected into the substrate material, the fiber core must lie lower than the waveguide.
An additional disadvantage is that the boundary surface is not realized vertically with respect to the axis of the fiber, but is inclined so that it can receive the diagonally incident light emitted from the waveguide. The fiber end is also correspondingly cut at an angle. One significant disadvantage of this arrangement is that such a diagonal boundary surface, which has an undercut, cannot be manufactured using molding techniques, but requires complex, time-consuming and expensive precision machining operations. Likewise, the beveling of the end of the fiber is a complex, time-consuming and expensive step.
EP 0 560 043 B1 describes passive integrated optical components with a molding made of polymer material that have optical waveguide structures and fiber guide structures. In this case, the grooves are rectangular grooves, into which the fibers are inserted into the grooves and optical waveguide core material is introduced. As a result of the different diameters of the optical waveguide and the optical fibers, the grooves have different depths. Consequently, at the point of contact where the end of the fiber meets the optical waveguide, there must be a step. Similar stepped structures are described in "Precision components for optical fibre connections fabricated by the LIGA
process", by Arnd Rogner, SPIE., Vol. 1973, pp. 94-100, and EP 0 324 492. Web-like structures are WO 99!67667 6 PCTIEP99104298 used only where exclusively waveguide structures are connected to each other.
The manufacturing methods generally provide that a substrate is provided with a step, the height of which can be precisely achieved, for example, by diamond milling. Then the stepped substrate is provided with a resist. During the subsequent synchrotron irradiation, a mask is used, the waveguide area and fiber area of which each have the shape of a rectangular aperture This mask is oriented with respect to the step of the substrate so that the fiber area and the waveguide area on the mask overlap with the later fiber area and the waveguide area on the coated substrate That means that the transition from the fiber area and the waveguide area of the mask must lie on the step, which requires a complex positioning of the mask. In the next step, the printing and development of the resist are done using galvano forming; a mold insert is manufactured which forms the negative. The mold insert is molded to create the final molding by means of hot stamping or injection molding. This molding has the corresponding groove, into which the optical fiber is inserted or into which the waveguide material is cast.
A disadvantage of this manufacturing process is that the step must be realized with great precision. In particular, the substrate may not have any burrs on the edge of the step, because the burr represents an undercut and can lead to disruptions during the galvano forming and the molding. In this case, the proper function of the coupling of optical waveguides and optical fibers can no longer be performed. Depending on the manufacturing technique used for the substrate and the step, such a burr can be avoided only with a relatively great deal of effort and expense. For example, the burr always occurs during fly-cut milling if the cut of the milling cutter runs from the area of the step over the edge.
.r'.
An additional disadvantage of such a groove structure is that during the filling of the waveguide core material into the optical waveguide structure, the material can flow into the guide structure for the glass fiber, so that the fiber embedding material and the waveguide core material cannot be selected independently of each other.
Finally, the fibers must be provided with a diagonal terminal surface to minimize reflections.
The object of the invention is to create a coupling element that is easy to manufacture, has a structure in the coupling area that does not adversely affect the coupling, and in which the optical waveguide material and embedding material can be selected independently of each other.
The invention teaches a coupling device in which a web made of waveguide cladding material is located as an integral component of the coupling element in the coupling area between the guide groove of the optical waveguide and the guide groove of the optical fiber.
The starting point for the invention was the knowledge that optical fibers and optical waveguides cannot be connected to each other directly, but must be offset by some distance from each other in the axial direction. It was discovered that in contrast to a lateral offset or an angular error, an axial offset has only a slight effect on the coupling loss. One surprising feature of this discovery was that this low caupling loss could be achieved in both single-mode and multi-mode technology if the dimensions and refractive indices of the optical waveguide are appropriately selected.
Because the optical fibers and the optical waveguides do not abut each other directly, but are separated from each other by a web, during the manufacturing process, the v z critical edge of the stepped substrate, e.g. the above-mentioned burr, is covered by the web, as a result of which a significantly simpler manufacturing process becomes possible.
The separation of the optical waveguide and the optical fiber by the web also offers greater flexibility in the selection of the waveguide core material and the embedding material for the optical fiber For example, in couplers of the prior art, the embedding material had to be the same as the waveguide core material. As a result, a reflection occurs at the boundary surface between the optical fiber and its embedding material, so that the reflected portion must be deflected by a relatively complex diagonal cutting of the optical fiber.
With the coupling element claimed by the invention, the embedding material can be selected so that the refractive index need only be appropriately the same as that of the fiber core material. Any remaining reflection at the boundary surface between the fiber embedding material and the web (waveguide cladding material) can be deflected by a diagonally cut surface of the web.
The web thus has the advantage, among other things, that one or both surfaces of the web can have a structure which makes it unnecessary to process the extremity of the optical fiber, for example.
An additional advantage that results from the use of two different materials is that the fiber embedding material can be selected in terms of its adhesive and strength properties, and the waveguide core material in terms of its optical transparency. Any penetration of the materials in question into the other guide groove is prevented by the web.
WQ 99/67667 9 PCTlEP99104298 The surface of the web (light entry surface) facing the guide groove of the optical fiber preferably has an inclined diagonal surface that encloses an angle cp of between 2° and 10° with a line perpendicular to the longitudinal axis of said guide groove. The perpendicular line preferably lies in the plane of the optical coupling element, so that the inclined surface can be seen in an overhead view of the coupling element. The width and height of the inclined surface are preferably equal to or greater than the diameter of the core of the optical fiber that the inclined surface faces. The reflection back into the optical fiber is eliminated by the selection of an appropriate angle for the inclined surface. Thus there is no need to bevel the terminal surface of the optical fiber.
Independently of or in addition to the configuration of the light entry surface, the surface of the web (light exit surface) that faces the guide groove of the optical waveguide can form an angle ~ of between 0.1 ° and 2° with a line perpendicular to the longitudinal axis of the guide groove of the optical fiber. That means that the two longitudinal axes of the guide grooves of the optical fiber and the optical waveguide also enclose the angle ~.
This configuration leads to a bent arrangement, whereby the angle ~ is set to the angle cp, taking into consideration the refractive indexes of the materials used, thereby achieving an optimal coupling efficiency.
The guide structure for the optical waveguide is advantageously widened toward the light exit surface, so that it becomes possible to transmit the light cone realized by the web completely into the core of the optical waveguide.
In an additional realization, there can be a plurality of guide grooves for optical waveguides and optical fibers next to one another. In this embodiment, there is a common web at a right angle to the guide grooves, whereby both the guide grooves for v z WQ 99!67667 10 PCTIEP99104298 the optical fibers and the guide grooves for the optical waveguides are connected to one another by means of at least one transverse groove that is oriented parallel to the web. Such transverse grooves increase the stability and mechanical strength of the mold insert used during the manufacture and are used to limit shrinkage during the molding.
The guide grooves for the optical waveguide or waveguides as well as the guide grooves for the optical fiber or fibers and the web are preferably fabricated in one piece from polymer material using molding processes.
The invention teaches that it is advantageous to select the web thickness less than 100 Nm, and preferably less than 50 pm.
The invention is explained in greater detail below with reference to the exemplary embodiments illustrated in the accompanying drawings.
Figure 1 is a view of the coupling element in perspective, Figure 2 is a view, in perspective, of a substrate with resist and mask for the printing, Figure 3 is an overhead view of the coupling element illustrated in Figure 1 to show the beam path, Figure 4 is a view in perspective of an additional embodiment of a coupling element, and Figures 5a are a sketch and a diagram respectively to explain the reflection loss as a and 5b function of the axial offset.
Figure 1 shows a coupling element 20 with guide grooves in the farm of a fiber groove 21 and a waveguide groove 22. The fiber grooves 21 and waveguide grooves 22 are not directly in contact with each other, but are separated from each other by a web 23.
The width of the web zs (See Figure 5a) is in the range of 5 - 100 Nm. The waveguide grooves 22 widen in the direction of the web 23, which is designated the taper 25, as a result of which the optical field that widens as it passes through the web 23 can be better received by the waveguide core, which is also explained in greater detail with reference to Figure 3.
The web 23, on its surface 40 (light entry surface) facing the fiber groove 21, has an inclined surface 24, which is inclined, for example, at an angle of cp =
8° with respect to the line 60 (See Figure 3) perpendicular to the longitudinal axis 61 of the fiber guide structure. As illustrated in Figure 3, the total light entry surface is formed by the inclined surface 24. The inclined surface 24 is inclined in the horizontal direction and extends over the entire depth of the groove 21. As a result of this inclined surface 24, light reflected by the light entry surface 40 does not run back into the optical fiber. This feature is particularly advantageous if the refractive index of the material used to embed the optical fiber is approximately equal to that of the core material of the optical fibers.
The coupling element 20 is preferably manufactured by means of a combination of LIGA and precision machining operations, and is described below with respect to the manufacture of a coupling between a standard single-mode fiber (fiber diameter pm, fiber core diameter approximately 8 Nm) and a square single-mode waveguide with an edge length 8 Nm, in conjunction with Figure 2. The starting point for the manufacture is the substrate 1 with a step 4, the height of which is very precisely set, for example, by diamond milling cutters to ho = 58.5 ~ 1 Nm. Then this substrate is coated with resist 3 and the height of the resist is thereby adjusted by polishing so that r~.
WO 99167667 12 PCTlEP99/04298 in the low fiber area 5 it is h2 = 66.5 pm and in the flat waveguide area 7 h~
= 8 Nm.
During the subsequent synchrotron irradiation, a mask 6 is used which has a waveguide area 9 and a fiber area 8 which are separated from each other by a web 28. The mask has structures for waveguide grooves 27 in the form of a rectangular opening with d~ _ 8 pm and for fiber grooves 26 in the form of a rectangular opening with d2 =
125 Nm.
This mask is oriented with respect to the substrate step 4 so that the fiber area 8 and the waveguide area 9 on the mask 6 coincide with the fiber area 5 and the waveguide area 7 on the coated substrate. The next step is the irradiation and development of the resist, as a result of which fiber grooves 21' and waveguide grooves 22' are formed, which are separated from one another by the web 23'. One advantage achieved by the formation of the web 23' is that the burr 9 that is inevitably formed during the manufacture falls on the step 4 of the substrate 1 in the area of the web 23', and is thus completely covered by the resist 3. In this case, the end of the fiber groove 21' is the image of the absorber structure provided on the mask 6, and does not result from the lateral surface 2 of the substrate step 4. The manufacturing process is thereby significantly simplified, and manufacturing-related problems on the substrate 1 cannot influence the coupling of the optical fibers and optical waveguides. As is known from LIGA technology, the next step is the manufacture of a mold insert by the galvano forming and its molding by hot stamping or injection molding. The optical fiber is then inserted into the fiber groove 21 of the coupling element 20 (See Figure 1 ), and the waveguide material is introduced into the waveguide grooves 22.
Using this manufacturing process, an accuracy of the orientation of the waveguide groove 22 with respect to the fiber grooves 21 of less than 1 Nm can be achieved.
Figure 3 illustrates the optical function of the coupling in detail. In the coupling element 20, the figure shows the fiber cladding material 35, the fiber core 36, the waveguide cladding material 37 and the waveguide core 38. The entire coupling element 20 is made of waveguide cladding material. The end of the waveguide facing the web widens in the form of the taper 38b. The inclined surface 24 of the web 23 is also in front of the fiber end surface 42. The space between the fiber end and the inclined surface 24 is filled with a fiber embedding material 41. Exiting from the fiber core 36 is the light cone 39 which is refracted on the beveled surface 24 and then widens. This light cone is completely received by the waveguide 38 that widens an the front end. The adjacent taper 38b causes the field to be transformed back to its original width.
In accordance with Snell's law of refraction, the magnitude of the refractive angle ~ is a function of the angle cp and of the refractive indexes of the fiber embedding material and waveguide material. It is particularly advantageous to orient the waveguide core 38 at an angle so that its longitudinal axis 62 coincides with that of the refracted light cone 39.
That means that the light exit surface 44 of the web 23 facing the waveguide 38 is also oriented at an angle. In this manner, an optimal coupling efficiency is achieved.
With regard to the intensity of the reflection, it is important that the light from the fiber core 36 to the waveguide 38 passes a plurality of boundary surfaces. These surfaces, in order, are the boundary surface (fiber end surface 42) between the fiber core 36 and fiber embedding material 41, the inclined boundary surface 43 between the fiber embedding material 41 and the waveguide cladding 37, and the boundary surface (light exit surface 44) between the waveguide cladding 37 and the waveguide core 38.
Theoretically, the reflection on the individual boundary surfaces is greater, the greater the difference between the refractive indexes on both sides of the boundary surface.
WO 99167667 14 PCTlEP99/04298 Because the materials for the waveguide cladding 37 and core 38 are generally selected on the basis of their optical transparency and their processing characteristics, their refractive indexes are already defined. A typical material for the waveguide cladding, for example, is PMMA, which has a refractive index of 1.49, which differs significantly from the refractive index of the optical fiber cladding, which is 1.45. It is particularly advantageous to use a material for the fiber embedding material 41 that is different from the material used for the waveguide core 38 and advantageously has the same refractive index as the fiber core 36. Consequently, practically no backward reflections will occur on the corresponding boundary surface (fiber end surface) 42. The same is true for the light exit surface 44, because the refractive indexes of the waveguide core and waveguide cladding are generally close to each other. The principal portion of the reflection therefore occurs on the boundary surface 43 and the light cone 45 is formed. The light cone is inclined by the angle 2cp as a function of the law of reflection with respect to the fiber end surface. In that case, it is particularly advantageous to select the angle cp large enough (e.g. cp = 4°), so that the light reflected back can no longer be received by the fiber core and therefore there is no reflection back into the optical fiber.
An additional advantageous configuration of the invention is illustrated in Figure 4. The coupling element 30, which is shown in perspective, has a plurality of fiber grooves that lye next to one another, of which the fiber grooves 21 and 31 are visible. The two fiber grooves 21 and 31 are connected to each other by a groove 32 that runs in the transverse direction. The same is true for the waveguide grooves 22 and 33 that lie next to each other and are connected to each other by the likewise transverse groove 34.
This configuration has the advantage that it significantly simplifies assembly, because the core material, when it is introduced into the guide structure, can be distributed more effectively and thereby reduces the risk of unfilled spaces. This advantage becomes particularly important when two different materials are used for the waveguide core and to embed the optical fibers. An additional advantage is that as a result of the transverse W z W,O 99/67667 15 PCT/EP99104298 grooves 32 and 34, a higher stability and mechanical strength of the mold insert is achieved, and that the transverse grooves 32 and 34 limit shrinkage during the molding process.
Figures 5a and 5b show the fiber waveguide coupling losses as a function of the axial offset zS. The geometry on which the calculation is based is illustrated in Figure 5a.
Optical fibers 46 with fiber core 47 and wavve guides with cladding 48 and core 49 are separated from each other by the distance zs. Between the fiber and waveguide end lies the waveguide cladding material 50 which has the refractive index 1.49. The results are calculated in Figure 5b for three typical applications.
(i) shows the coupling of a square step index waveguide with an edge length of 55 Nm and a numerical aperture of 0.219 into a gradient index fiber with a core diameter of 62.5 Nm and a numerical aperture of 0.275.
(ii) shows the coupling in the reverse direction, i.e. from the gradient index fiber into the waveguide. In both cases, the calculations were based on a wavelength of 850 mm, which is typically used for multi-mode systems in the field of short-distance connections.
The increase in the loss in both cases is slow, and for zs = 100 Nm, for example, is less than 2.5 dB.
(iii) shows the coupling of a single-mode fiber with a core diameter of 9 Nm and a numerical aperture of 0.1 into a square step index waveguide with a core diameter of 8 Nm and a numerical aperture of 0.1. For the coupling in the reverse direction, we get the same result. The calculation was based on a wavelength of 1300 nm, which is WO 99!67667 16 PCTIEP99104298 typically used in the field of telecommunications for long-distance connections. The loss increases slowly, and for zs = 100 Nm, for example, is less than 0.75 dB.
Nomenclature 1 Substrate 2 Lateral surface 3 Resist 4 Step Fiber area (substrate) 6 Mask 7 Waveguide area (substrate) 8 Fiber area (mask) 9 Waveguide area (mask) 20 Coupling element 21 Fiber groove 21' Fiber groove 22 Waveguide groove 22' Waveguide groove 23 Web 23" Web 24 Diagonal surface 25 Taper 26 Fiber groove structure 27 Optical waveguide structure 28 Web 29 Burr 30 Coupling element 31 Fiber groove 32 Transverse groove 33 Waveguide groove 34 Transverse groove 35 Fiber cladding 36 Fiber core 37 Waveguide cladding 38 Waveguide core 38b Taper 39 Light cone 40 Light entry surface 41 Fiber embedding material 42 Fiber end surface 43 Boundary surface 44 Light exit surface 45 Light cone 46 Optical fiber 47 Fiber core 48 Optical waveguide cladding 49 Optical waveguide core 50 Optical waveguide cladding material 60 Perpendicular line 61 Longitudinal axis 62 Longitudinal axis _.
Claims (6)
1. Optical coupling element which is manufactured in one piece using molding technology from polymer waveguide cladding material, with at least one each guide groove for an optical wav guide and an optical fiber, characterized by the fact that in the coupling area between the guide groove (22) of the optical waveguide and the guide groove (21 ) of the optical fibers, there is a web (23) of waveguide cladding material which is an integral component of the coupling element.
2. Coupling element as claimed in Claim 1, characterized by the fact that the surface (40) of the web (23) (light entry surface) that faces the guide groove (21 ) of the optical fiber has an inclined surface (24), which encloses an angle ~
between 2° and 10° with a line (60) perpendicular to the longitudinal axis (61 ) of this guide groove.
between 2° and 10° with a line (60) perpendicular to the longitudinal axis (61 ) of this guide groove.
3. Coupling element as claimed in one of the Claims 1 or 2, characterized by the fact that the surface (44) of the web (23) (light exit surface) facing the guide groove (22) of the optical waveguide forms an angle ~ between 0.1 ° and 2° with a line (60) perpendicular to the longitudinal axis (61 ) of this guide groove (21 ).
4. Coupling element as claimed in one of the Claims 1 to 3, characterized by the fact that the guide groove (22) for the optical waveguide widens toward the light exit surface (44).
5. Coupling element as claimed in one of the Claims 1 to 4, characterized by the fact that a plurality of guide grooves (21, 22, 31, 33) for optical waveguides and optical fibers are located next to one another, that a common web (23) extends transverse to the guide grooves (21, 22, 31, 33), and that both the guide grooves (21, 31 ) for the optical fibers and the guide grooves (22, 33) for the optical waveguides are connected to one another by means of at least one transverse groove (32, 34) that is oriented parallel to the web (23).
6. Coupling element as claimed in one of the Claims 1 to 5, characterized by the fact that the web thickness is < 100 µm, and is preferably < 50 µm.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19827553.6 | 1998-06-20 | ||
| DE19827553A DE19827553A1 (en) | 1998-06-20 | 1998-06-20 | Optic coupling element for optical sensors and communication systems |
| PCT/EP1999/004298 WO1999067667A1 (en) | 1998-06-20 | 1999-06-21 | Optical coupling element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2335045A1 true CA2335045A1 (en) | 1999-12-29 |
Family
ID=7871522
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002335045A Abandoned CA2335045A1 (en) | 1998-06-20 | 1999-06-21 | Optical coupling element |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP1090319B1 (en) |
| JP (1) | JP2002519711A (en) |
| AT (1) | ATE230120T1 (en) |
| CA (1) | CA2335045A1 (en) |
| DE (2) | DE19827553A1 (en) |
| WO (1) | WO1999067667A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8644662B2 (en) | 2010-05-24 | 2014-02-04 | Nitto Denko Corporation | Optical connection structure and production method of optical waveguide to be used for the optical connection structure |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2376754A (en) * | 2001-06-22 | 2002-12-24 | Bookham Technology Plc | Optical chip substrate with a channel having a stepped profile |
| KR100846241B1 (en) * | 2003-11-28 | 2008-07-16 | 히다치 가세고교 가부시끼가이샤 | Optical element coupling structure |
| JP2010015135A (en) * | 2008-06-03 | 2010-01-21 | Hitachi Cable Ltd | Optical waveguide substrate with optical fiber fixation groove, process for its production, stamp for use in this production process, and opto-electronic hybrid integrated module including the optical waveguide substrate |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4865407A (en) * | 1987-10-22 | 1989-09-12 | Brother Kogyo Kabushiki Kaisha | Optical waveguide element, method of making the same and optical coupler employing optical waveguide element |
| EP0560043B1 (en) * | 1992-03-07 | 1997-06-18 | Minnesota Mining And Manufacturing Company | Manufacturing method of devices for lightguide networks and elements produced using this method |
| DE4208278A1 (en) * | 1992-03-13 | 1993-09-16 | Bosch Gmbh Robert | Integrated optical component eg modulator or switch - provides polymer optical conductor running on polymer material filling positioning slanted trench at connection with glass fibre |
| JP2975499B2 (en) * | 1993-04-28 | 1999-11-10 | 京セラ株式会社 | End structure of optical waveguide substrate and method of manufacturing the same |
| US5343544A (en) * | 1993-07-02 | 1994-08-30 | Minnesota Mining And Manufacturing Company | Integrated optical fiber coupler and method of making same |
| JPH08122561A (en) * | 1994-10-21 | 1996-05-17 | Fujitsu Ltd | Method for connection between optical waveguide and optical fiber and optical waveguide type device |
| WO1998057206A1 (en) * | 1997-06-10 | 1998-12-17 | Minnesota Mining And Manufacturing Company | Rib-type integrated optical interconnect |
-
1998
- 1998-06-20 DE DE19827553A patent/DE19827553A1/en not_active Withdrawn
-
1999
- 1999-06-21 EP EP99929295A patent/EP1090319B1/en not_active Expired - Lifetime
- 1999-06-21 AT AT99929295T patent/ATE230120T1/en not_active IP Right Cessation
- 1999-06-21 JP JP2000556267A patent/JP2002519711A/en active Pending
- 1999-06-21 CA CA002335045A patent/CA2335045A1/en not_active Abandoned
- 1999-06-21 WO PCT/EP1999/004298 patent/WO1999067667A1/en active IP Right Grant
- 1999-06-21 DE DE59903844T patent/DE59903844D1/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8644662B2 (en) | 2010-05-24 | 2014-02-04 | Nitto Denko Corporation | Optical connection structure and production method of optical waveguide to be used for the optical connection structure |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2002519711A (en) | 2002-07-02 |
| WO1999067667A1 (en) | 1999-12-29 |
| EP1090319B1 (en) | 2002-12-18 |
| ATE230120T1 (en) | 2003-01-15 |
| DE59903844D1 (en) | 2003-01-30 |
| EP1090319A1 (en) | 2001-04-11 |
| DE19827553A1 (en) | 1999-12-30 |
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