WO1998050809A1

WO1998050809A1 - In-coupling and out-coupling devices for radiation guides in a communications network

Info

Publication number: WO1998050809A1
Application number: PCT/CH1998/000183
Authority: WO
Inventors: Bernhard Valk; Olivier Anthamatten; Werner Hunziker
Original assignee: Ascom Tech Ag
Priority date: 1997-05-06
Filing date: 1998-05-06
Publication date: 1998-11-12

Abstract

The invention relates to a device (9) for in-coupling / out coupling radiation which has been guided or is to be guided into radiation guides (7a-7d; 11a-11d) for use in a communications network. In this method, several radiation guides (7a-7d; 11a-11d) are arranged parallel to each other. In accordance with the number of radiation guides (7a-7d; 11a-11d), transmitting and/or receiving diodes (33a-33d) are epitaxially integrated in a detector plate (17) at a mutual distance from the radiation guides. The radiation guides are fitted with elements (45a, 45b, 49) for coupling partial radiation (47) into or out of the diodes (33a-33d), in accordance with the diode positions. The detector plate (27) with integrated diodes (33a-33d) is placed directly on the guides (7a-7d; 11a-11d) with no radiation guide element as an intermediate layer. The invention is characterized by an extremely compact structure as the distance between the coupling element (45a, 45b, 49) and the diodes (33a-33d) is extremely small. Adjustment of the coupling elements (45, 45, 49) is substantially simplified as the diodes (33a-33d) are an integral part of the detector plate (17); a single component has to be adjusted. In an alternative version of the invention, adjustment is further facilitated by positioning members (29a).

Description

One-Z decoupling devices for radiation conductors in a communication network

The invention relates to a method for producing a coupling / decoupling device according to the preamble of patent claim 1 and a coupling / decoupling device according to the preamble of patent claim 4.

In the following, an input / output coupling device for radiation-physical connection conductors of a communication network is referred to as a fiber duplexer, which can have a different number of channels. For example, in the embodiment shown below, the fiber duplexer has four channels. A fiber duplexer is thus understood to mean a coupling / decoupling device in radiation-physical communication, which allows coupling of a transmission signal onto a connecting conductor connecting the subscribers and coupling of the returning signals from the same conductor onto a photodetector.

FIG. 1 shows a typical telecommunications structure for signal transmission between a control center 1 and a plurality of end points 3. In control center 1, a transmission diode 5 and a passive splitter (coupler) 6 are used on a plurality of radiation conductors (single-mode or multimode conductors) 7a to 7n Signals for the corresponding end points 3a and 3b applied. The end points 3a and 3b shown here are only examples; other versions are of course possible. Here, for example, work is carried out at a wavelength of 1.3 μm. The center 1 has the transmitter diode 5 and a multi-channel fiber duplexer 9 with the channels 9a to 9n. Each channel 9a to 9n is connected to the transmitter diode 5 via a radiation conductor 7a to 7n. The output side A of the duplexer 9 is connected to the respective terminal 3 via transmission lines 11a to 11n. The end point 3 can now be designed, inter alia, as a reflecting modulator 3a or as an active duplexer 3b. In terminal 3, the input signal from transmitter diode 5 is superimposed on the terminal signal and sent back towards the transmitter. In the control center 1 the end position signal is then received by means of a photodiode via the relevant channel of the duplexer. These end point signals are each processed with an amplifier 13a to 13n assigned to a channel 9a to 9n of the multi-channel duplexer 9 and processed further in the control center 1. The amplifiers 13a to 13n can also be arranged outside the multi-channel duplexer.

WO 96/00920 describes an optical unit for a single radiation conductor, from which a partial radiation is coupled out, which is detected with a photodiode. The decoupling element is a 45 ° separation point in the radiation conductor, from which the partial radiation passes through an intermediate layer as the radiation conductor. A photodiode for detection is then arranged on the intermediate layer. The intermediate layer is provided with a through hole, at the end of which the photodiode is located.

OBJECT OF THE INVENTION The object of the invention is to demonstrate a manufacturing method which can be carried out simply and inexpensively, and to provide a radiation-physical multi-channel fiber duplexer which is compact and easy to use.

Solution of the task

The object is achieved in that the duplexer according to the invention is compactly constructed only from an extremely small number of components and no special adjustment handles are required during assembly; Also, no devices have to be used to check the correct adjustment of the built-in components. The invention allows an extremely compact structure, since the distance from the coupling element to the diodes is extremely small. Since the diodes are an integral part of the detector plate, the adjustment with regard to the coupling elements is also considerably simplified; only one component has to be adjusted. The adjustment is also greatly facilitated by positioning means of an embodiment variant. In contrast to WO 96/00920, in the invention, partial radiation is not guided by radiation coupling-in coupling elements through an intermediate layer to a photodiode. In the invention, the partial radiation is guided directly into a detector plate in which the transmitting and / or receiving diodes are integrated. Compared to WO 96/00920, the invention therefore not only has one component less, the diodes are also significantly closer to the coupling element in question. It has been shown that the arrangement of WO 96/00920 can only be used for an arrangement with a single radiation conductor. If several radiation conductors are used, the arrangement of WO 96/00920 does not allow a compact structure, since otherwise the signals from neighboring radiation conductors are crosstalked. The invention, on the other hand, allows an extremely compact structure, since only through it is a short distance from the coupling element to the transmitting and / or receiving diodes possible.

Since the transmitting and / or receiving diodes are an integral part of the detector plate, the adjustment with regard to the coupling elements is also considerably simplified; only one component has to be adjusted. The adjustment is also greatly facilitated by positioning means of a performance variant.

For example, an oblique, end-side grinding of the ends of the radiation conductor, coating of at least one final grind and subsequent joining of the two ends creates a coupling-out element for part of the radiation coming from the end point.

The arrangement according to the invention is designed in such a way that the partial radiation to be coupled out or coupled out from a radiation conductor hits the active region of the diodes integrated in the detector plate without additional imaging optics.

The entire structure is selected such that only the ends of the radiation conductors that belong to one another are inserted in a marked location in guide grooves, pushed together and a detector plate provided with form-fitting adjusting elements has to be inserted into the corresponding adjusting elements of a base plate carrying the guide grooves under self-adjustment and then cast. A complex adjustment is no longer necessary. Since conductor bundles, the individual conductor fibers of which are arranged equidistantly and rigidly in position, are preferably used, there is an assignment of the individual radiation conductors to one another, which is not lost even after a grinding and coating process of the ends. Twisting the individual conductors is no longer possible. Advantages, further exemplary embodiments and variants result from the following description text.

Brief description of the invention

Examples of the method according to the invention and of the fiber duplexer according to the invention are explained in more detail below with reference to figures. Show it:

1 is a block diagram of a typical telecommunications structure for signal transmission between a control center and several end stations,

2 shows a longitudinal section along a radiation conductor longitudinal axis of a multi-channel duplexer for, for example, four radiation conductors, FIG. 3 shows a cross section along the line III-III in FIG. 2,

4 shows a plan view of a base plate of the duplexer shown in FIGS. 2 and 3 without a radiation conductor and with the detector plate removed,

5 shows a top view of the top of the detector plate with four integrated photodiodes, FIG. 6 shows a perspective sketch of three radiation conductors, the radiation coupling / decoupling elements of which are formed from a non-continuous incision with a filter inserted, and

Fig. 7 shows a cross section through one of the coupling elements shown in Figure 7 with indicated beam and coupled out partial beam.

FIG. 2 shows in longitudinal section and FIG. 3 in cross section a four-channel fiber duplexer 9. On the left side of FIG. 2, the conductors 7a to 7d (single-mode or multimode fibers) carrying the radiation come in as radiation conductors coming from the transmitter diode 5 this one. On the right-hand side of the picture, the transmission conductors 11a to 11d leave the control center 1 in the direction of the terminal 3. The conductors 7a to 7d and 11a to 11d each have the fiber protective sheath (primary or secondary coating) 15 or 16 immediately after entering the or before leaving the duplexer 9 removed. The fiber cladding 17 and 18 and the radiation-guiding fiber core (core) 19 and 20 of the conductors 7a to 7d and 11a to 11d are continued. The fiber jackets 17 and 18 are held laterally in guide grooves 21a to 21d of a base plate 23. The guide grooves 21a to 21d are clearly visible in cross section in FIG. 3 and in a plan view in FIG. 4.

The guide grooves 21a to 21d are V-shaped for aligning the inlet and outlet conductors 7 and 11, respectively. They have equidistant lateral distances, which here are, for example, 0.25 mm. In addition to the grooves 21a to 21d, markings 25a to 25e are arranged on a straight line, approximately in their longitudinal central position. Outside the groove arrangement, approximately centrally to the connecting line of the markings 25a to 25e, a positioning recess 26a and 26b is arranged on both sides for a detector plate 27 in the base plate 23. The positioning recesses 26a and 26b have prismoid-like side walls.

The detector plate 27, as can be seen in particular in FIG. 5, is rectangular and has a bridge-like cross section with projections 29a and 29b projecting downwards. The dimensions of the lugs 29a and 29b are selected such that, as will also be explained below, they position the detector plate 27 exactly on the base plate 23 with respect to the markings 25a to 25e. In the detector plate 27, for example, four photodiodes 33a to 33d z. B. integrated by means of an epitaxial method. Their geometric centers are arranged along a straight line 32. The electrical conductors 34 for the photodiodes 33a to 33d run on the surface 31 and are guided laterally above the lugs 29a and 29b to a respective connection field 35a or 35b with the corresponding connection points 37. The connection points 37 are connected to the corresponding conductor tracks 42 on the base plate 23 via bonded or soldered wires 40. The base material of the detector plate 27 is transparent to the radiation guided in the conductors 7 and 11.

The side 43 facing away from the upper side 31, so to speak the underside of the bridge, lies on the conductors 7 and 11 with tolerances in the assembled state.

The conductor ends of the here, for example, four radiation conductors 7 and 11, each combined in a bundle, have an end bevel in a range from approximately 40 ° to 50 ° to the conductor axis. An angle of exactly 45 ° should be avoided so that unwanted radiation reflections are not coupled back into the conductors 11 (11a-11d). The grinding surfaces 45a of the fiber jackets 17 and cores 19 and the grinding surfaces 45b of the fiber jackets 18 and cores 20 lie in a plane running perpendicular to the longitudinal axes of the conductors 7 and 11. One of the grinding surfaces 45a or 45b, here the grinding surface 45b, has an optical coating 49 which has a part 47 the radiation 48 arriving in the core 20 is reflected out of the latter. The radiation coming or passing from the end point 3a or 3b in the continuous radiation conductor is identified by 48 or 46. The coating is selected in such a way that about 50% of the radiation power comes out from the end point 3a or 3b; the same applies to the transmission signal. The ground conductor ends are joined at their connection point 50 such that the conductors 7a to 7d are aligned with the conductors 11a to 11d. The radiation coming from or reflected from the terminal 3 strikes the corresponding photodiodes 33a to 33d through the underside 43 of the detector plate 27 . The other 50% pass the junction 50 to the relevant terminal 3.

The arrangement of the markings 25a to 25e and the positioning recesses 26a and 26b as well as the design of the detector plate 27 and its projections 29a and 29b as well as the locations of the diode integration in the detector plate 27 are selected such that the partial radiation coupled out through the contact surface 45b in each case active area of the photodiodes 33a to 33d, provided the upper end of the respective abutment surface 45a and 45b lies at the location of the respective marking 25a to 25e and the lugs 29a and 29b of the detector plate 27 are inserted into the positioning recesses 26a and 26b.

To construct an optical fiber duplexer 9 for four bundled transmission conductors 11a to 11d, for example, the ends of the bundled transmission conductors 11a to 11d to be combined in the duplexer and those of the likewise bundled conductors 7a to 7d, which lead to the transmitter diode 5, in the end region from Protective jacket 15 and 16 exempt. The cleared area is larger by a grinding and assembly tolerance than the distances of the markings 25a to 25e from the start of the guide grooves 21a to 21d. Subsequently, the bundled conductors 7a to 7d and 11a to 11d, freed from the protective sheath 15 and 16 in the end region, are glued to a grinding base with a detachable resin in order to give the conductor ends stability during the upcoming grinding process. The ends of the conductors 7a to 7d and 11a to 11d are now ground under the angle range listed above (between 40 ° and 50 °). The grinding of the conductor ends of the transmission conductors 11a to 11d is chosen in accordance with FIG. 2 such that the partial radiation 47 to be coupled out can be guided upwards into the detector plate 27. After grinding, the resin is removed again and the grinding surfaces 45a and 45b cleaned. Subsequently, the grinding surfaces, here for example the grinding surfaces 45b, are provided with a coating which, in the assembled and glued state, reflects (decouples) and transmits approximately 50% of the radiation 48 arriving from the terminal 3 as a partial beam 47. The same applies analogously to the radiation 46 coming from the transmitter diode 5. The portion reflected at the connection point 50 penetrates the base plate (if this consists of transparent material) and is absorbed by the absorber 36 on the rear side of the base plate 23.

In a subsequent work step, the ends of the conductors 7a to 7d and 11a to 11d are inserted or pushed into the guide grooves 21a to 21d in such a way that the contact surfaces 45a and 45b take into account the correct alignment, as already explained above, are at the location of the markings 25a to 25e. Inserting the conductor ends is made easier by the inlets 51 and 52 shown in FIG. The position is checked optically (microscope, stereo microscope, camera, ...). The detector plate 27 is placed on the inserted conductor ends and everything is fixed with an adhesive (epoxy resin, UV-curing adhesive, ...) that is transparent to the radiation carried in the conductors. The conductor ends are pushed together in such a way that a gap remains which is sufficient for the adhesive to penetrate. The detector plate 27, i.e. whose photodiodes 33a to 33d are automatically aligned via their projections 29a and 29b, which rest in the positioning recesses 26a and 26b, to the exact course of the partial beams 47, the connection point 50 of which was previously aligned with the markings 25a to 25e.

The base plate 23 will preferably be made of silicon using the so-called "silicon motherboard" technology. It is a technology that is already well established in semiconductor manufacturing. Such a silicon base plate can also be used as a "master" for an injection molding process. This "master" can also be pressed into a thermoplastic material to produce the structures of a base plate. For the wavelength range from 1 μm to 1.6 μm mentioned here, the detector plate consists of indium phosphide with epitaxially grown photodiodes made of indium gallium arsenide. An execution in the infrared radiation range is of course not mandatory; with a suitable choice of materials, it can also be worked in the visible.

The (multi-channel) duplexer according to the invention, as described above, is characterized in particular by its compact structure and inexpensive manufacture, which uses techniques which are already sufficiently known. The construction elements (base plate 23, detector plate 27 with integrated diodes and the bevelled grinding of the conductor ends) are designed according to the invention in such a way that they no longer have to be actively adjusted. Everything is just put together (self-adjustment). After being plugged together, both the conductors and the beam splitters are precisely aligned with regard to the detectors 33a-33d for the partial radiation. All components can be easily fixed to each other with a single glue.

Instead of designing the duplexer for four incoming and four outgoing (mono or multimode) conductors, as is explained here for example, it can also be designed for more or fewer conductors. Since the conductors are arranged firmly to one another due to the bundling, fewer markings than the five shown in FIG. 4 are sufficient for identifying the position of the decoupling element (contact surfaces).

Instead of grinding the conductor ends at the angles listed above and only then inserting and gluing them into the guide grooves, you can also insert them into the guide grooves arranged on a base plate without grinding and then grind and coat the base plate and conductor together. In this case the base plate would be two pieces instead of one. The exact joining of the two base plates could take place via aligned blind holes or further guide grooves on the surface of the base plates by means of dowel pins.

Instead of using form-fitting positioning elements for self-adjustment on the detector plate and the base plate, overlapping soldering points can be arranged for self-adjustment on both adjacent surfaces. When the solder becomes liquid, the detector plate then floats automatically into the desired position specified by the solder points on the base plate.

The base plate 23 can be dispensed with if the guide grooves for the conductors are arranged directly on the detector plate. The conductor ends could only be glued directly to the detector plate. The adhesive point could also be covered with a cover plate. In this case, the markings will be placed on the detector plate.

The detector plate with the photodiodes integrated in the top can also be mounted with this top down directly above the radiation conductors. In this case, the detector plate can consist of non-transparent material.

Instead of just a coupling-out coating (mirroring) on one end of the conductor, both adjacent conductor ends can also be coated. It a decoupling that deviates from 50% can also be selected depending on the intended use. The coating can also be formed by a suitable selection of a layer ensemble in such a way that only certain wavelength ranges are coupled out or in. A certain polarization direction can also be preferred in this way.

Instead of a bevel and a coating of the conductor ends, a structure can also be produced in a continuous conductor, for example as a lattice-like change in refractive index by UV radiation. This grid then carries out the appropriate coupling or decoupling. It can also be used to generate a decoupling element

Groove 53 are sawn into the continuous conductor (multimode fiber), for example with a diamond saw. The continuous conductors are designated 55a to 55c in FIG. The "sawing angle" (cutting angle) to the conductor axis has a value slightly different from 45 ° in order to avoid back reflections. A correspondingly coated plate 57 (plate made of glass, plastic film,... With a thickness of ~ 30 μm) is then inserted into this groove 53, possibly using an adhesive to adjust the refractive index. The plate 57 is placed over the sawn-in conductors 55a to 55c of the conductor bundle 59, as indicated in FIG. 6. The plate 57 decouples only a part 60 of the beam cross-section 61 (FIG. 7) that propagates in the conductors 55a to 55c, provided that a cross-section can be spoken of in the case of a wave guided in a radiation conductor. Here too, a detector plate 63 with integrated diodes, of which only a 64 is shown, lies directly on the conductors 55a to 55c. The plate 57 can be coated in order to achieve a filter effect when coupling out the partial radiation. A filter sheet can also be inserted in addition to the plate.

Instead of sawing in, it can also be sawed through at the location of the marking with radiation guides already inserted. A plate with or without a filter sheet is then inserted into this cut for decoupling.

Claims

claims

1 . Method for producing a coupling / decoupling device (9) for radiation guided or to be guided in radiation conductors (7a - 7d; 11a - 11d; 55a - 55c) for use in a communication network, characterized in that several radiation conductors (7a - 7d; 11a - 11d; 55a - 55c) arranged parallel to each other, corresponding to the number of radiation conductors (7a - 7d, 11a - 11d; 55a - 55c) at their mutual spacing, transmitting and / or receiving diodes (33a - 33d; 64) in a detector plate ( 17; 63) epitaxially integrated and the radiation conductors with radiation coupling elements (45a, 45b, 49; 57) corresponding to the diode positions for coupling / decoupling a partial radiation (47; 60) into and from the diodes (33a - 33d; 64) and the detector plate (27; 63) having the integrated diodes (33a - 33d; 64) is placed directly on the radiation conductors (7a-7d; 55a - 55c) without the interposition of a radiation guide element.

2. The method according to claim 1, characterized in that the radiation conductors (7a - 7d, 55a - 55c) laterally immovable by markings (24a - 25e) for the position of the coupling elements (45a, 45b, 49; 57) and positioning means (26a, 26b, 29a, 29b) are held for the base plate (23) having the detector plate (17; 63), and the detector plate (17; 63) is merely inserted into the positioning means (26a, 26b, 29a, 29b) and preferably detector and Base plate (17, 23) and the radiation conductors (7a - 7d; 55a - 55c) are glued with an adhesive that is transparent to the radiation they supply.

3. The method according to claim 1 or 2, characterized in that the radiation conductors (55a-55c) are partially sawn through to form the coupling elements, preferably sawn through, preferably sawing with radiation conductors (55a-55c) inserted in a base plate, in particular is carried out in one operation over all inserted radiation conductors (55a - 55c).

4. coupling / decoupling device (9) for in a radiation conductor (7a-7d, 11a-11d) guided or to be guided radiation of a communication network, produced by a method according to one of the claims 1 to 3, characterized by several in parallel Radiation conductors (7a-7d, 55a - 55c) and a detector plate (17; 63) with epitaxially integrated transmitting and / or receiving diodes (33a - 33d.) arranged opposite each other, each having a radiation coupling / decoupling element (45a, 45b; 49; 57) ; 64), the detector plate (17; 63) being aligned in this way directly, without any radiation-conducting intermediate layer, on the radiation conductors (7a - 7d; 55a - 55c) or the coupling elements (45a, 45b; 49; 57).

5. Device according to claim 4, characterized by a base plate (23) with lateral guides (21a-21d) for each radiation conductor, the base plate (23) in particular a marking for identifying the position of the respective coupling element (45a, 45b; 49; 57) and preferably positioning means (26a, 26b, 29a, 29b) for exact positioning of the detector plate and thus its integrated diodes (33a - 33d; 64) with respect to the coupling elements (45a, 45b; 49; 57).

6. Device according to claim 4 or 5, characterized by radiation conductor end faces, which have a slightly different angle from 45 ° to the conductor axis and are connected to one another to form a coupling element, in particular are glued.

7. Device according to claim 5 and 6, characterized in that the lateral guides (21a - 21d) have an inlet for the radiation conductor ends to be inserted.

8. Device according to claim 4 or 5, characterized in that the coupling elements are formed as a groove (53) sawn into the radiation conductors (55a-55c), the angle of intersection with the conductor axis having a slightly different angle from 45 °, and preferably into that A radiation filter (57) is inserted.

9. Device according to one of claims 4 to 8, characterized in that

the radiation conductors (7a - 7d; 55a - 55c) are glued to the detector plate (17; 63) and preferably also to the base plate (23) with a transparent adhesive.