Patent Application
20230305235
The present invention relates to a multi-coupler having a first group of optical sending elements and a second group of optical receiving elements, wherein either the first group or the second group comprises more than two elements. Each optical sending element is associated with a transmitting element, which is configured and arranged such that a divergent beam bundle emanating from the optical sending element is converted into a convergent beam bundle and diverted to an optical receiving element. The convergent beam bundle converges in a focal point.
An example of such a multi-coupler is an optical multiplexer or demultiplexer.
The so-called wavelength multiplexing method, which represents an optical frequency multiplexing method, is generally used for the transmission of signals to fibre optic. In the multiplexing method, light signals having different frequencies are used for the transmission. Each frequency used provides its own transmission channel to which the actual data to be transmitted can be modulated. The data signals modulated in this manner are then bundled by means of respective optical coupling elements and transmitted simultaneously, but independently of one another. At the receiver of this optical multiplexed link, in a demultiplexer, the individual optical transmission channels are then separated again using respective passive optical filters and converted into electrical signals with corresponding sensor elements.
Optical multiplexers and demultiplexers have long been known. Generally, a multiplexer can also be used as a demultiplexer by reversing the beam path and vice versa. Instead of sensors, which generate the respective light signals to be transmitted, only lasers need be used, which convert the transmitted optical signals into electrical signals. Reference to a demultiplexer is therefore often made below. However, it will be appreciated that the described features of a demultiplexer can also be applicable to multiplexers, wherein the beam direction is simply reversed.
Generally, demultiplexers comprise an optical sending element, which can consist of, for example, a fibre optic via which multiple signal channels are transmitted. A divergent beam bundle is then emanated from the end of the fibre optic, which is transmitted to multiple optical receiving elements by a suitable sending element. In principle, all devices that can receive and/or evaluate optical signals, such as light sensors, waveguide ends, or grid couplers, are considered optical receiving elements.
For example, the divergent beam bundle can first be converted into a substantially parallel beam bundle, which is then passed sequentially through specially arranged optical filters, each allowing a section of the signal channels to pass through while reflecting a different section of the signal channels. Such an arrangement is also known as a filter cascade and is typically configured such that each optical filter separates a wavelength channel from the remaining signal. The separate channels are then also present as parallel beam bundles and are then directed through corresponding focussing elements to the optical receiving element provided for the respective signal channel. For example, if six signal channels are transported over the fibre optic at the same time, the corresponding multiplexer comprises one optical sending element and six optical receiving elements.
It is understood that an optimal signal sensing will only occur when all elements are arranged and aligned exactly to one another. In the production of such demultiplexers, but also in other optical multi-couplers, a relatively large effort is therefore made to position the individual elements very precisely to one another. Despite the greatest effort, this is not always possible, so that a small proportion of produced products cannot achieve the desired specifications and can be classified as a rejection.
It is usually already sufficient that only a single element used in the optical multi-coupler is not positioned precisely enough, so as to render the entire optical multi-coupler unusable.
Thus, against the background of increasing complexity of multiplexers and demultiplexers due to a variety of additional channels, which results in an increase in the elements used in the optical multi-coupler, the rejection rate automatically increases.
In order to meet the increased requirements for the exact positioning and alignment of each individual element in an optical multi-coupler, a much higher effort must therefore be expended, which is in practice hardly feasible and leads to an increased rejection rate despite all efforts.
Against the background of the described prior art, the problem addressed by the present invention is therefore to provide an optical multi-coupler that poses lesser demands for the positioning and orientation of the individual elements and still can map the optical signals provided by the optical sending elements to the optical receiving elements in a highly precise manner. The problem of the present invention is also to specify a method that allows optical multi-couplers to be set very precisely with little effort.
According to the present invention, this problem is solved in that a correcting element is positioned between an optical sending element and an optical receiving element and is configured such that
In other words, faults in the system due to inaccurate positioning and arrangement of individual elements of the optical multi-coupler are corrected using the correcting element. In addition, deviations due to production tolerances of the component used can be corrected very easily.
A misalignment or misorientation of one or more elements of the optical multi-coupler can result in the focal point no longer lying exactly on the optical receiving element or the convergent beam not having the desired angle on the optical receiving element. In addition, the polarization state of the convergent beam bundle may not correspond to the desired polarization state. Also, the field shape of the convergent beam bundle, i.e. the intensity distribution in a sectional view perpendicular to the propagation direction of the convergent beam bundle, may not be homogeneous or may not correspond to the desired field shape.
In all such cases, which can also occur simultaneously, the misalignment can be corrected by providing a correcting element between an optical sending element and an optical receiving element. Optical multi-couplers that do not meet their requirements and have thus been considered as rejects so far can be reused with the aid of the correcting element. Moreover, the requirements for the exact positioning and orientation of the elements can be reduced, because any misalignments that can occur are corrected by the provision of a correcting element.
This can significantly reduce production costs as a result.
In a preferred embodiment, it is provided that the transmitting element comprises at least a first collimator and at least a second collimator, wherein a first collimator is associated with each optical sending element, which is configured and arranged in such a way that the first collimator converts a divergent beam bundle emanating from the optical sending element into a parallel beam bundle. Furthermore, each optical receiving element is associated with a second collimator, which is configured and arranged in such a way that a beam bundle directed from the first collimator to the second collimator is converted into a convergent beam bundle and diverted to the respective optical receiving element.
Thus, a divergent beam bundle exiting from an optical sending element is converted by the associated first collimator into a parallel beam bundle and optionally transmitted to a second collimator via one or more optical filters and converted by said collimator into a convergent beam bundle that is diverted towards the optical receiving element associated with the second collimator.
The number of first collimators preferably corresponds to the number of optical sending elements, while the number of second collimators corresponds to the number of optical receiving elements.
In a further preferred embodiment, it is provided that multiple first collimators and/or multiple second collimators are joined together in a material-locking manner, wherein multiple first collimators and/or multiple second collimators are preferably formed from one material piece.
For example, after the arrangement of sending elements and receiving elements as well as the arrangement of the transmitting elements, a test can be performed in order to draw conclusions about the position of the focal point, the angle at which the convergent beam bundle impinges on the optical receiving element, the polarization state of the convergent beam bundle, and/or the field shape of the convergent beam bundle. The test result is then compared to the respective desired values and a corresponding correcting element is then created, which, when positioned in the correct position, brings the test value at least closer to the desired value.
The respective test values can be sensed immediately from multiple transmitting elements and then multiple correcting elements can be produced together and positioned accordingly, such that, in particular when a large number of optical receiving elements are used in the optical multi-coupler, by positioning only one correcting component which includes all correcting elements, the optical multi-coupler can be produced in a significantly more time-saving manner and thus less expensive.
In a further preferred embodiment, it is provided that multiple first collimators and/or multiple second collimators are configured as curved reflective surfaces. It is particularly expedient when the reflective surface has approximately the shape of a section of a rotational paraboloid, a rotational ellipsoid, or a rotational hyperboloid. In other words, the reflective surface follows the outer surface of a rotational body, at least piecewise. This results in a section through the reflective surface along a cutting surface perpendicular to the axis of rotation having approximately a circular section shape, while a section along a plane in which the axis of rotation lies is approximately the shape of a section of a parabola, hyperbola, or ellipse. Such a curved reflective surface has particularly suitable mapping properties.
In a further preferred embodiment, the correcting element comprises an entry surface and an exit surface and is positioned between an optical sending element and an optical receiving element such that the beam bundle enters the correcting element via the entry surface and exits the correcting element via the exit surface. Alternatively, the correcting element could also be configured as a mirror.
For example, the correcting element can be a prism, wherein the entry surface and the exit surface are preferably not arranged parallel to one another.
The entry surface of the prism and/or the exit surface of the prism can be curved in configuration.
Furthermore, the correcting element can be a lens.
In principle, the correcting element can be arranged at any position between an optical sending element and an optical receiving element. In a preferred embodiment, however, it is provided that the correcting element is arranged between a first collimator and a second collimator. Between the first collimator and the second collimator, the beam bundle is substantially parallel.
The optical multi-coupler can be configured as a multiplexer/demultiplexer. In a further preferred embodiment, the optical multi-coupler is configured as an optical rotary transmitter. Such a rotary transmitter is used in order to transmit optical signals between units that are rotated relative to one another. They are therefore also called rotary couplers or rotary transmitters.
In a further preferred embodiment, it is provided that the correcting element comprises a main section and a subsequent compensation section, wherein the main section comprises the entry surface and the compensation section comprises the exit surface, wherein the main section consists of a material having a first refractive index and the compensation section consists of a material having a second refractive index, wherein the first and second refractive indexes are different.
With this measure, the optical multi-coupler will only depend slightly on the correct positioning of the correcting element, so that no increased requirements for the correcting element and its positioning need be posed.
In a preferred embodiment, an interface between the main section and the compensation section is not configured parallel to the entry surface, but the exit surface preferably runs parallel to the entry surface.
Furthermore, a correcting component can be provided, which comprises a plurality of correcting elements, such that by positioning the correcting component, multiple correcting elements are correctly positioned.
The aforementioned problem is also solved by a method for producing an optical multi-coupler, having the following steps:
Advantageously, at least a first collimator and at least a second collimator are used as the transmitting element, wherein
Furthermore, the present invention relates to a method for producing a correcting element that can be used in an optical multi-coupler as described above or in a method as described above. The method comprises the following steps:
In order to produce the correcting element according to the invention, a punch is therefore produced which has a mould surface that is formed as the negative to the desired surface of the correcting element. In the simplest case, the surface of the correcting element is level but inclined towards a reference plane. In this case, the punch also has a planar mould surface, which however in step 3) is pressed onto the surface of the material in an inclined configuration. If the correcting element is to have a convex surface, the mould surface must be concave.
The following further developments of the method can be carried out altogether or in any combination with one another:
In step 1), the material can consist of two material sections. For example, a glass panel can be provided with a thermoplastic coating, such that in step 2) only the thermoplastic coating is heated until the coating transitions into the thermoplastic or liquid state.
In step 2), the heating can be carried out with the aid of a laser beam, which is preferably focused on the part of the surface that is to come into contact with the mould surface.
For example, the laser beam can be diverted into the material from the side facing away from the surface to be heated.
Step 3) can be carried out several times in a row when the transparent material is displaced from time to time so that the punch comes into contact with different surface portions. As a result, a correcting component comprising multiple correcting elements is created. Alternatively, the punch can also be moved laterally between two successive steps 3).
If step 3) is performed several times in a row, the angle at which the punch is oriented towards the surface of the material can be changed between operations. In successive pressing-in steps, different punches having different mould surfaces can also be used.
Further advantages, features, and possible applications of the present invention will become apparent from the examples shown in the following figures. The following are shown:
In
Due to incorrect positioning and incorrect adjustments, however, it may be that the parallel light beam or beam bundle does not impinge as desired on the collimator 3, but rather tilts opposite the optimal direction of impingement. This is shown in
In
The two examples clearly show that even small misalignments can lead to the signal no longer reaching the optical receiving elements or no longer reaching them at full signal strength.
If the optical sending element is now not arranged at the actually provided position 7, but rather laterally offset at the position bearing the reference number 8 and from there a diverging beam bundle is directed onto the first collimator 6, this leads, as can be seen in
If this distance is too large, the optical multi-coupler cannot be used. It must therefore be ensured in the prior art that the optical sending element is precisely arranged at the position provided for it.
Instead of the exact positioning of the optical receiving element, as suggested according to the invention, a correcting element can instead be positioned in the beam path. In this case, as shown in
It can immediately be discerned that a small deviation of the position of the correcting element 10 has almost no effect on the focal point 4, so that it is much easier to position the correcting element 10 in the beam path than to position the optical sending element exactly at the intended position.
In
In this case, a concave lens is used as the correcting element 12, which changes the profile of the parallel beam bundle such that it is mapped in the desired focal point 4.
In
According to the invention, it is therefore provided that a glass plate 15 is placed in the beam path, as shown in
In
In
The parallel beam bundle then impinges on a second collimator 3, which converts the beam bundle into a convergent beam bundle, which is to be directed towards the associated optical receiving element 19.
Again, a misalignment has occurred in the bottom-most case, so that, as shown by the dashed line, the focal point lies outside of the optical receiving element 19. By providing a correcting element 23, the beam path is corrected and now impinges on the optical receiving element 19, as made clear by the solid line.
In
According to the present invention, a correcting element 25 is therefore also provided here, as shown in
In
According to the present invention, it is therefore provided that the exact position of the focal points is measured and then, if it does not match the desired position of the focal points, a corresponding correcting element is determined and produced. Such a correcting element is shown in
The correcting element can consist of a prism, as already explained. In
First, a material consisting of a bearing plate 40, e.g. a glass plate, and a thermoplastic layer 41 arranged thereon is provided (
Next, as shown in
The punch is then optionally inclined opposite a vertical on the surface of the thermoplastic coating 41 and then moved towards the thermoplastic layer 41 until approximately the position shown in
With the laser beam 42, the thermoplastic coating 41 has become soft so that the punch 43 can penetrate into the thermoplastic layer 41. The laser beam 42 is then turned off so that the thermoplastic coating 41 cools again and becomes dimensionally stable. As soon as it is ensured that the thermoplastic layer 41 retains its shape, the punch 43 can be moved away from the material again.
Now, either the punch 43 or the material can be moved laterally and the heating step as well as the pressing-in step can be repeated at another position such that a plurality of correcting elements 44 are formed on the thermoplastic layer 41. The result is a correcting component 45 having multiple (in the example shown, three) correcting elements 44.
The individual correcting elements 44 can differ from one another by, for example, changing the angle that the punch 43 encloses with a vertical on the surface of the coating 41. Alternatively, other punches, such as the alternative punches 43′ and 43″ shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 102022107005.0 | Mar 2022 | DE | national |
