Optical coupling module, test unit, method for producing an optical coupling module, method for optically testing an element to be tested using a test unit, and control unit

Abstract

The present invention relates to an optical coupling module (100) having a module carrier (110) with a surface (125) and a waveguide (120), which protrudes obliquely from the surface (125) of the module carrier (110) at a connection point (115), for outputting optical test signals (143) to an element (135) to be tested.

Description

[0001] Optical coupling module, test unit, method for manufacturing an optical coupling module, method for optically testing a test element using a test unit and control unit

[0002] The approach presented here relates to an optical coupling module, a test unit, a method for manufacturing an optical coupling module, a method for optically testing a test element using a test unit, and a control unit according to the dependent claims. Such a module and method are known by design from US 2011 / 0279812 and WO 2019 / 029765.

[0003] From W02021 / 078318 A1, a wafer-level test method is known for testing optoelectronic chips arranged on a wafer with electrical interfaces in the form of contact pads and fixed optical interfaces in the form of optical deflection elements. In three adjustment steps, the wafer with one of the chips is aligned with a contacting module such that the electrical interfaces of the chip and the contacting module are in contact with each other and the optical interfaces of the chip and the contacting module (2) assume a maximum position of optical coupling. The method is relatively complex and requires high positioning accuracy of the contacting module.

[0004] US patent 2006 / 0109015 A1 discloses an optoelectronic probe module for testing chips (device under test - DUT) with electrical and optical inputs and outputs. If, as described in US patent 2006 / 0109015 A1, the coupling efficiency of the optical signal is optimized by collimating or focusing the optical beam, the entire probe module must be adjusted with high precision in the sub-pm range, which is very complex.

[0005] US Patent 2011 / 0279812 discloses a contact module for testing chips with electrical and optical inputs and outputs. The chip is mounted on a movable carrier, which allows for rough alignment with the contact module. This rough alignment is sensor-controlled, based on position monitoring of the chip or its alignment marks. This method is complex and prone to errors. US Patent 7412138 discloses optoelectronic alignment structures for wafer-level testing of optical and optoelectronic chips. This wafer-level test system uses optical and electronic probes to locate and align to an optoelectronic alignment structure and includes adjustment for maximum performance. The alignment procedure and structures are relatively complex.

[0006] For testing optoelectronic devices, a suitable test unit is required for wafer-level testing in the high-volume production of, for example, photonic integrated circuits. A key feature of such a test unit is its plug-and-play compatibility with existing wafer-level test equipment and wafer probers used in the high-volume production of conventional ICs. To enable this, the insufficient positioning accuracies of conventional wafer probers for reproducible optical coupling should be compensated for by a suitable, position-tolerance-insensitive optical coupling principle. Currently, test units can be used to measure, for example, PICs where light is coupled to the surface via grating couplers (GCs). However, this method achieves insufficient light coupling for wafer-level testing of optoelectronic chips due to frequent misalignment.

[0007] Against this background, the present invention aims to create a possibility for improved optical testing of an element to be tested.

[0008] This problem is solved by the subject matter of the collateral patent claims.

[0009] The approach presented here creates an optical coupling module with the following features: a module carrier with a surface; and a waveguide protruding obliquely from the surface of the module carrier at a connection point for outputting optical test signals to an element under test.

[0010] A module carrier can be understood, for example, as a single-piece or compact component on which the waveguide is arranged or protrudes. A surface, in this context, can be understood as, for example, a main surface of the module carrier, which is directed towards or pressed onto the element under test. A connection point can be understood as a location where the waveguide is attached, allowing an optical test signal to couple from the module carrier to the waveguide at this point. A waveguide, in this context, can be understood as an optical fiber or a mode-guiding element from which light, coupled into the waveguide, for example, through the entry point, is emitted as an optical test signal to an element under test located external to the waveguide.The waveguide can have a core and a cladding. The core can have a higher refractive index than the cladding. However, the waveguide can also be cladding-free. In this case, the surrounding air with a refractive index close to 1 can ensure optical wave guidance in the core. The waveguide can be single-mode with respect to the wavelength of the optical test signals. It can also be multi-mode. The optical test signals themselves can be single-mode. Single-mode test signals can also be transmitted over short distances through a multi-mode waveguide, so a multi-mode waveguide can be used in this case as well. A multi-mode waveguide can have the advantage over a single-mode waveguide that the waveguide core can have a larger cross-section.This means that a lower degree of alignment accuracy with the element being tested may be sufficient to transmit the optical test signals. Alternatively, the test signals can be multimode. Single-mode test signals can be generated with a laser, while multimode test signals can also be generated with an LED (light-emitting diode).

[0011] The approach presented here is based on the understanding that using a waveguide extending from or away from the module carrier significantly improves the ability to output optical test signals to the element under test. For example, such a waveguide can compensate for misplacement relative to the element under test, such as at a connection point, because the protruding waveguide typically provides a much larger coupling area than can be achieved with individual coupling pads or coupling areas on the surface of the module carrier.At the same time, the distance between the module carrier and the element under test can be reduced to such an extent that the element under test is pressed against the module carrier, so that the waveguide is positioned between the element under test and the surface, and the corresponding optical test signals can be efficiently coupled into the element under test. Damage to the waveguide is usually not a concern, since the movement paths from the waveguide to the element under test during contact can simply be kept small, which, in the case of a flexible waveguide, only results in non-critical mechanical stresses.

[0012] A further advantage of the approach presented here is an embodiment in which the waveguide is designed as an optical fiber, and / or in which the length of the waveguide corresponds to at least five times, and advantageously at least ten times, its width, and / or in which the waveguide is designed as a glass fiber. Such an embodiment offers the advantage of minimizing the mechanical stress on the waveguide through its specific design and / or enabling the largest possible coupling area for optical test signals from the waveguide to the element under test.

[0013] According to a further embodiment of the approach proposed here, the module carrier and the waveguide can be formed in one piece, or the waveguide can be attached to the module carrier at the connection point, in particular by bonding. Such an embodiment offers the advantage of being able to manufacture the combination of module carrier and waveguide very flexibly and cost-effectively according to the desired optical and material specifications. It is also possible to attach the waveguide to the module carrier, for example, by splicing or by soldering with a glass solder. Splicing can be understood as a welding process in which the connection point can be locally melted.

[0014] To allow for the most flexible possible contact between the waveguide and the element under test, the waveguide can extend in an arc across the surface.

[0015] Another conceivable embodiment of the approach proposed here involves the waveguide being at least partially aligned parallel to the surface and / or having a flexible shape. Such an embodiment offers the advantage of enabling the largest possible coupling area between the waveguide and a corresponding coupling area of ​​the element under test.

[0016] Furthermore, according to another embodiment of the approach proposed here, the waveguide can contact the surface at an end opposite the connection point. Such an embodiment offers the advantage that the coupling behavior of an optical test signal via the waveguide can be monitored and evaluated specifically at the end of the waveguide opposite the connection point, thus enabling a spatial separation of the output of the optical test signal and the monitoring of the coupling behavior.

[0017] One embodiment of the approach proposed here is particularly robust against mechanical stresses, in which the waveguide has a spring element that supports the waveguide against the surface between a region of the connection point and an end opposite the connection point.

[0018] Very low optical losses in the output of the optical test signal are made possible by an embodiment of the approach proposed here in which a module carrier waveguide is embedded in the module carrier, which is designed to guide the optical test signals to the connection point in the waveguide.

[0019] According to another embodiment of the approach proposed here, an additional waveguide projecting obliquely from the surface of the module carrier at a further connection point can be used to output further optical test signals to the element under test. Such an embodiment enables the testing of the element under test with a plurality of optical test signals, which, for example, can be coupled into the element under test at different positions and / or output independently of one another and, for example, simultaneously. In this way, increased flexibility in testing the element under test can be achieved.

[0020] A further advantage is an embodiment of the approach proposed here as a test unit for optically testing a test element, wherein the test unit has the following features: an optical coupling module according to a variant of an embodiment presented here; and an analysis unit configured to send an optical test signal through the optical coupling module to the test element and to evaluate a test signal received from the test element.

[0021] Such an embodiment allows the aforementioned advantages to be realized quickly, cost-effectively, and efficiently. A further advantage is an embodiment of the approach proposed here as a method for manufacturing an optical coupling module according to a variant of an embodiment presented here, wherein the method comprises the following steps:

[0022] Providing a modular support structure, and

[0023] Forming a waveguide protruding obliquely from the surface of the module carrier at a connection point for outputting optical test signals to an element under test.

[0024] Such an embodiment allows the aforementioned advantages to be realized quickly, cost-effectively and efficiently.

[0025] An optical coupling module can be manufactured particularly easily and cost-effectively if, according to one embodiment, the forming step involves exposing, in particular etching, the waveguide from a material of the module carrier and / or forming the waveguide by means of 3D printing and / or bonding the waveguide to the surface of the module carrier at the connection point. In this case, technically mature and cost-effective methods for manufacturing such an optical coupling module can be used.

[0026] A further advantage is an embodiment of the approach proposed here as a method for optically testing a test element using a variant of an embodiment of a test unit presented here, wherein the method comprises the following steps:

[0027] Applying the optical test signal to the element under test using the optical coupling module; and

[0028] Evaluating a test signal or evaluation signal received from the element under test.

[0029] Advantageously, the optical test signal can be transmitted from the waveguide to the element under test via evanescent coupling. For example, the cladding of the waveguide can be thinned or removed at a point designated for transmission. Alternatively, the core of the waveguide can be flattened at the transmission point to increase the degree of evanescent coupling. The evanescent coupling between the waveguide and the element under test can be achieved by placing the waveguide, with the transmission point designated, directly onto the element under test. Alternatively, the evanescent coupling can also be achieved via a gap between the waveguide and the element under test, without the need to place the waveguide directly onto the element under test. This latter method can therefore be contactless and thus wear-free with respect to the waveguide.In contrast, contact contact can have a higher degree of coupling than non-contact contact.

[0030] Furthermore, the optical testing procedure for a component under test can include decreasing the distance between the component under test and the coupling module before the test and increasing the distance between the component under test and the coupling module after the test. The decreasing and increasing of the distance can be performed in a direction normal to the surface of the component under test, which can be defined as a z-direction. This normal direction can be normal to the wafer plane if the components under test are located on the wafer. This wafer plane can be referred to as an xy plane, where xyz can form a Cartesian coordinate system. Decreasing the distance can be achieved, for example, by lowering the coupling module onto the component under test if the component under test is located in a plane below the coupling module.However, the distance can also be reduced by raising the element under test if the coupling module is located in a fixed plane above the element under test. Reducing the distance can be achieved, for example, by raising the coupling module onto the element under test if the element under test is located in a plane above the coupling module. It can also be achieved by lowering the element under test if the coupling module is located in a fixed plane below the element under test. Increasing the distance can then be done in the opposite direction. The terms "above" and "below" can be interpreted in terms of the force of gravity.

[0031] If the element under test is located above the coupling module, it can be inspected upside down. This can reduce the likelihood of contamination, for example, by falling particles. However, the likelihood of contamination of the coupling module may be increased compared to an upside-down inspection. Alternatively, the inspection can be performed vertically. This can mean that the normal direction of the element under test with respect to gravity is horizontal.

[0032] The above-mentioned methods can be implemented, for example, in software or hardware, or in a hybrid form of software and hardware, for example in a control unit.

[0033] The approach presented here further creates a control unit designed to execute, control, and implement the steps of a variant of the method presented here in appropriate devices. This embodiment of the invention, in the form of a control unit, also allows the underlying problem to be solved quickly and efficiently.

[0034] For this purpose, the control unit can have at least one processing unit for processing signals or data, at least one storage unit for storing signals or data, at least one interface to a sensor or actuator for reading sensor signals from the sensor or for outputting data or control signals to the actuator, and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The processing unit can be, for example, a signal processor, a microcontroller, or the like, and the storage unit can be flash memory or a magnetic storage device.The communication interface can be configured to read or output data wirelessly and / or via wired connections, whereby a communication interface that can read or output wired data can, for example, read this data electrically or optically from or output it into a corresponding data transmission line.

[0035] In this context, a control unit can be understood as an electrical device that processes sensor signals and outputs control and / or data signals accordingly. The control unit can have an interface, which may be implemented in hardware and / or software. In the case of a hardware-based interface, the interfaces can, for example, be part of a so-called system ASIC, which incorporates various functions of the control unit. However, it is also possible that the interfaces are separate integrated circuits or at least partially comprised of discrete components. In the case of a software-based interface, the interfaces can be software modules, which, for example, are located on a microcontroller alongside other software modules.

[0036] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular if the program product or program is executed on a computer, a control unit or generally a device.

[0037] Examples of the approach presented here are shown in the drawings and explained in more detail in the following description. It shows:

[0038] Fig. 1 shows a schematic representation of an embodiment of an optical coupling module;

[0039] Fig. 2 shows a further embodiment of an optical coupling module;

[0040] Fig. 3 shows a schematic representation of an embodiment of an optical coupling module, now in a side view;

[0041] Fig. 4 shows a flowchart of an embodiment of a method for manufacturing an optical coupling module;

[0042] Fig. 5 shows a flowchart of an embodiment of a method for optically testing a test element;

[0043] Figure 6 shows a block diagram of an exemplary embodiment of a control unit for the manufacture of an optical coupling module;

[0044] Figure 7 shows a block diagram of an embodiment of a control unit for optical testing of a test element; and Figure 8 shows a schematic representation of another embodiment of an optical coupling module.

[0045] In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and acting similarly, without repeating these elements.

[0046] Figure 1 shows a schematic representation of an embodiment of an optical coupling module 100. The optical coupling module 100 comprises a module carrier 110 on which a waveguide 120 is arranged at a connection point 115. The waveguide 120 is arranged such that it exits obliquely from a surface 125 of the module carrier 110 at the connection point 115 and is guided in an arc or as a curved web over the surface 124, so that it contacts the surface 125 again, for example, at an end 130 opposite the connection point 115. The surface 120 can be a primary surface facing a device under test (DuT = Device under Test).To couple optical test signals into the waveguide 120, a module carrier waveguide 140 is formed in the module carrier 110. Light signals from a light source 142 are coupled as optical test signals 143 into the waveguide 120 via this waveguide to the connection point 115. During a test operation of the element 135 under test, the distance shown in Figure 1 is significantly reduced, for example, because for one test mode the optical coupling module 100 is pressed onto the surface of the element 135 under test. This brings the waveguide 120 very close to a coupling area 145, so that, through evanescent coupling, at least some of the light from the optical test signals couples from the waveguide 120 into the coupling area 145, thereby enabling the testing of optical parameters or properties of the element 135 under test.

[0047] It is also conceivable that by reflecting a portion of the light from the optical test signal at the end 130 or by detecting it at a location, it can be determined what proportion of the light power from the waveguide 120 has coupled into the coupling area 145, so that a corresponding evaluation of the coupling quality can also be performed here. It is also conceivable that in a return path, light from the coupling area 145 is coupled into the waveguide 120 and, for example, as evaluation signals 147, is coupled into the module carrier waveguide 140 via the connection point 115, which then acts as the entry point, and is led to an evaluation unit 150, which is located, for example, in the area of ​​the light source 142.By evaluating the evaluation signals 147, the element 135 to be tested can then be checked for correct functionality, for example, a test unit 155 with the light source 142, the optical coupling module 100 and the evaluation unit 150 can be realized.

[0048] It is also possible that several of the waveguides 120 shown in Figure 1 protrude from the module carrier 110 at different positions or at an angle, and thus different coupling areas 145 of the element 135 to be tested can be supplied with corresponding optical test signals 143.

[0049] The direction z shown can be the direction of gravity. In this case, the DUT is tested upside down. In a first variation of this example, the direction z can be opposite to gravity. In this case, the DUT is tested upside down, i.e., from above. In a second variation of this example, the direction z can be perpendicular to the direction of gravity. In this case, the DUT is tested vertically.

[0050] Figure 2 shows a representation of another embodiment of an optical coupling module 100. In contrast to the optical coupling module 100 constructed according to Figure 1, the waveguide 120 is now not stretched in an arc over the surface 125, but has a straight section 200. In addition, the waveguide 120 is supported by a spring element 210, which provides resilient support to the waveguide 120 in the region of the end 130.If, for a test mode, the optical coupling module 100 is pressed downwards in a test direction 220, so that, for example, the straight section 200 of the waveguide 120 is pressed onto the coupling area 145, the optical test signal 143 can be coupled into a waveguide 230 of the device under test (DUT) by means of the design of this coupling area 145 as an evanescent coupler. An optical signal fed back from the coupling area 145 can then be fed back into the waveguide 120 via the coupling area 145. In this way, an optical function of the element 135 under test can be tested by evaluating a received and transmitted evaluation signal 147. Figure 3 shows a schematic representation of an embodiment of an optical coupling module 100 in a side view. It can be seen that the module carrier waveguide 140 has a smaller cross-section than the waveguide 120.In this way, it can be ensured that the light power of the optical test signal 143 from the module carrier waveguide 140 is fully coupled into the waveguide 120 and thus delivered as efficiently as possible. For this purpose, the waveguide under test 230 can also have a smaller width in the coupling area 145 than the waveguide 120, so that there is as large an overlap as possible between the waveguide under test 230 and the waveguide 120, thus enabling the most efficient coupling of light from the waveguide 120 into the waveguide under test 230.

[0051] An important aspect of the approach presented here is that an existing UFO probe technology for testing PICs can be extended to systems where light is coupled evanescently. For this purpose, an optical coupling module 100 can be modified by extending one or more waveguides 120 out of the coupling module 100. These waveguides, for example, in the form of thin glass structures (thickness in the range of a few pm), guide the light under the coupling module 100, as shown in Fig. 2. To establish contact between the optical coupling module 100 and the element 135 (DuT) under test, the module 100 is brought so close to the element 135 (DuT) that these structures, or in this case the waveguides 120, press against the element 135 (DuT), thus enabling near-field coupling. Since the structures, or rather the waveguides 120, are thin, the optical coupling module 100 can be positioned as close as possible to the element 135 (DuT) under test.Because the waveguide 120 is relatively flexible due to its small size, a certain degree of positional inaccuracy in the z-direction (i.e., axially) can be compensated for. The lateral (x, y) positional tolerance of the probe system can be compensated for by the width of the extended waveguide 120, as schematically illustrated in Fig. 3. The coupling efficiency can be adjusted via the length of the structures.

[0052] The extraction of the waveguide(s) 120 from the optical chip as an optical coupling module 100 can be achieved additively or subtractively: In a first approach, structures for forming the waveguide 120 can be applied to the aforementioned structures or waveguides 120, or to the optical chip or module carrier 110 (for example, by 3D printing or deposition). In a second approach, these structures or waveguides 120 can be isolated from the glass block as the module carrier 110 of the optical coupling module 100. This is possible, for example, by laser-selective etching. The structures or waveguides 120 themselves can be implemented in different designs: They can be realized as a curved bridge (for example, as shown in Fig. 1) under the optical coupling module 100. This allows the signals 143 and 1443 to be transmitted.The signal 147 is fed back into coupling module 100, thus enabling, for example, feedback measurement (regarding the coupled intensity). The disadvantage is that the actual coupling path is difficult to implement due to the bending.

[0053] A particularly suitable solution is the implementation by means of a double solid-state joint, as shown in Fig. 2. This ensures that the coupling path between the coupling structure and the evanescent coupler remains constant. This can be achieved by providing the straight section 200 in the waveguide 120, which then enables or ensures a constant distance from the element 135 under test.

[0054] The approach presented here allows the UFO probe technology for wavelevel testing to be extended to PICs, where the light can be coupled in evanescently. Compared to the "classic" UFO, no grid couplers are required on the PICs. Furthermore, a significantly increased coupling efficiency can be expected, since less overexposure occurs during coupling (i.e., the transmission of the optical test signal 142 from the optical coupling module 100 to the element 135 or DuT under test), and no imaging of the emitted light into a waveguide 120 is necessary during output coupling (i.e., the transmission of the evaluation signal 147 from the element 135 or DuT under test to the optical coupling module 100).

[0055] Figure 4 shows a flowchart of an embodiment of a method 400 for manufacturing an optical coupling module according to a variant presented here, wherein the method 400 includes a step 410 of providing a module carrier 100 and a step 420 of forming a waveguide at a connection point projecting obliquely from the surface of the module carrier for outputting optical test signals to an element to be tested.

[0056] Figure 5 shows a flowchart of an embodiment of a method 500 for optically testing a test element using a variant of a test unit presented here, wherein the method 500 includes a step 510 of applying the optical test signal to the element to be tested using the optical coupling module and a step 520 of evaluating a test signal or evaluation signal received from the element to be tested.

[0057] Figure 6 shows a block diagram of an embodiment of a control unit 600 for manufacturing an optical coupling module according to a variant presented here, wherein the control unit 600 comprises a provision unit 610 for providing a module carrier 100 and a training unit 620 for forming a waveguide projecting obliquely from the surface of the module carrier at a connection point for outputting optical test signals to an element to be tested.

[0058] Figure 7 shows a block diagram of an embodiment of a control unit 700 for optically testing a test element using a variant of a test unit presented here, wherein the control unit 700 comprises an application unit for applying the optical test signal to the element under test using the optical coupling module and an evaluation unit 720 for evaluating a test signal or evaluation signal received from the element under test.

[0059] Fig. 8 shows a schematic representation of another embodiment of an optical coupling module. During the testing process of the element 135 under test, unlike the example shown in Fig. 1, the waveguide 120 of the optical coupling module 100 is placed on the surface of the element 135 under test, thus optimizing the coupling degree of the evanescent coupling of the optical test signals between the coupling area 145 and the waveguide 120. Fig. 8 also shows that an offset in the placement of the waveguide 120 relative to the coupling area 145, here in the x-direction, is tolerable within a certain tolerance range without impairing the coupling. In the illustration, the vertex of the optical waveguide is not exactly in the center of the coupling area 145, but slightly shifted to the left.After the testing process, the optical coupling module 100 can be lifted in the z-direction, for example to place it over another element 135 to be tested and to lower it for another testing process.

Claims

Patent claims 1. Optical coupling module (100) with the following features: a module carrier (110) with a surface (125); and a waveguide (120) projecting obliquely from the surface (125) of the module carrier (110) at a connection point (115) for outputting optical test signals (143) to an element (135) to be tested.

2. Optical coupling module (100) according to claim 1, wherein the waveguide (120) is configured as an optical fiber, and / or wherein a length of the waveguide (120) corresponds to at least five times a width of the waveguide (120), and / or wherein the waveguide (120) is configured as an optical fiber.

3. Optical coupling module (100) according to one of the preceding claims, wherein the module carrier (110) and the waveguide (120) are formed in one piece or wherein the waveguide (120) is attached to the module carrier (110) at the connection point (115), in particular by splicing, soldering or gluing.

4. Optical coupling module (100) according to one of the preceding claims, wherein the waveguide (120) extends in an arc shape over the surface (125).

5. Optical coupling module (100) according to one of the preceding claims, wherein the waveguide (120) is at least partially aligned parallel to the surface (125) and / or wherein the waveguide (120) is flexibly shaped.

6. Optical coupling module (100) according to one of the preceding claims, wherein the waveguide (120) contacts the surface (125) at an end (130) opposite the connection point (115).

7. Optical coupling module (100) according to one of the preceding claims, wherein the waveguide (120) has a spring element (210) which supports the waveguide (120) against the surface (125) between a region of the connection point (115) and an end (130) opposite the connection point (115).

8. Optical coupling module (100) according to one of the preceding claims, in which a module carrier waveguide (140) is embedded in the module carrier (110), which is configured is to guide the optical test signals (143) to the junction (115) in the waveguide (120), in particular wherein the module carrier waveguide (140) has a smaller width than the waveguide (120).

9. Optical coupling module (100) according to one of the preceding claims, comprising a further waveguide (120) projecting obliquely from the surface (125) of the module carrier (110) at a further connection point (115) for outputting further optical test signals (143) to the element (135) to be tested.

10. Test unit (155) for optically testing a test element (135), wherein the test unit (155) has the following features: an optical coupling module (100) according to one of the preceding claims; and an analysis unit (142, 150) configured to send an optical test signal (143) through the optical coupling module (100) to the test element (135), in particular wherein the optical test signal can be transmitted from the waveguide (120) to the test element (135) by means of evanescent coupling, and to evaluate a test signal or evaluation signal (147) received from the test element (135).

11. Method (400) for manufacturing an optical coupling module (100) according to any one of the preceding claims 1 to 9, wherein the method (400) comprises the following steps: Providing (410) a module carrier (110), and Forming (420) a waveguide (120) protruding obliquely from the surface (125) of the module carrier (110) at a connection point (115) for outputting optical test signals (143) to an element (135) to be tested.

12. Method (4009 according to claim 11, wherein in step (420) of forming, an exposure, in particular an etching of the waveguide (120) from a material of the module carrier (110) and / or a forming of the waveguide (1209) by means of a 3D printing and / or an gluing of the waveguide (120) at the connection point (115) to the surface (125) of the module carrier (110) is carried out.

13. Method (500) for optically testing a test element (135) using a test unit (155) according to claim 10, wherein the method (500) comprises the following steps: Applying (510) the optical test signal (143) to the element (135) to be tested using the optical coupling module (100); and Evaluating (520) a test signal or evaluation signal (147) received from the element (135) under test.

14. Control unit (400, 500) configured to execute and / or control the steps (410, 420; 510, 520) of one of the methods (600; 700) according to one of the preceding claims 11 to 12 or 13 in corresponding units (610, 620; 710, 720).

15. Computer program configured to execute and / or control the steps (410, 420; 510, 520) of one of the methods (600; 700) according to one of the preceding claims 11 to 12 or 13.

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