Directional coupler tester and testing method, device thereof

Abstract

This invention relates to the field of optical testing, and in particular to a directional coupler tester, its testing method, and apparatus, comprising an input coupler, an output coupler, a first waveguide, a second waveguide, a multimode interferometer, and a waveguide switching component; the multimode interferometer is used to split the test beam into a first test beam splitter and a second test beam splitter; the first waveguide and the second waveguide have different lengths; the waveguide switching component is disposed on the first waveguide and the second waveguide. This invention achieves a combination of direct measurement and interferometric measurement within the same directional coupler testing structure, avoiding the upper limit of accuracy that can result from fabricating multiple test structures with slightly different structures and performing direct and interferometric measurements separately, thus further improving the accuracy of the directional coupler splitting ratio test results.

Description

Technical Field

[0001] This invention relates to the field of optical testing, and in particular to a directional coupler tester and its testing method and apparatus. Background Technology

[0002] A directional coupler is a passive device in silicon-based optoelectronics, consisting of two parallel waveguides, used to combine or split optical signals. An important parameter of a directional coupler is the splitting ratio, which specifies the energy ratio between the two output ports when light enters through one input port.

[0003] Testing methods for directional couplers include direct testing and interferometric testing. Direct testing involves introducing light from an optical fiber into one input port of the directional coupler, then measuring the optical power at each of the two output ports, and finally calculating the splitting ratio. Interferometric testing involves first introducing light from an optical fiber into a multimode interferometer. The light from the multimode interferometer then passes through two waveguides of different lengths and enters the directional coupler from its two input ports. Finally, the optical power at each of the two output ports is measured. This causes interference / destruction at specific wavelengths between the two output ports of the directional coupler, and the splitting ratio is calculated based on the energy difference between these interference phases.

[0004] In practical applications, the same directional coupler operates at different wavelengths with varying splitting ratios. Some wavelengths have splitting ratios close to 1:1, while others have ratios far from 1:1. The problem is that when the splitting ratio is close to 1:1, the error obtained using direct testing methods is larger, while the error obtained using interferometry is smaller. Conversely, when the splitting ratio is far from 1:1, the error obtained using interferometry methods is larger, while the error obtained using direct measurement methods is smaller. This necessitates designing two separate test structures when testing directional couplers of the same specification. However, due to unavoidable manufacturing errors and other factors, the directional couplers of the same specification in the two test structures are not actually identical. This results in an upper limit to the accuracy of the test results, which is difficult to overcome.

[0005] Therefore, how to further improve the accuracy of the directional coupler splitting ratio test results has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a directional coupler tester and its testing method and apparatus to solve the problem of low accuracy in the prior art for testing the splitting ratio of directional couplers.

[0007] To solve the above-mentioned technical problems, the present invention provides a directional coupler tester, including an input optical coupler, an output optical coupler, a first waveguide, a second waveguide, a multimode interferometer, and a waveguide switching component;

[0008] The optical coupler is used to receive external test light and couple the test light into the multimode interferometer;

[0009] The multimode interferometer is used to split the test beam into a first test beam and a second test beam, and to transmit the first test beam to the first optical inlet of the directional coupler to be measured through the first waveguide, and to transmit the second test beam to the second optical inlet of the directional coupler to be measured through the second waveguide;

[0010] The first waveguide and the second waveguide have different lengths;

[0011] The light output coupler is disposed at the light output port of the direction coupler to be measured;

[0012] The waveguide switching component is disposed on at least one of the first waveguide and the second waveguide.

[0013] Optionally, in the directional coupler tester, the waveguide switching component is disposed on the first waveguide and the second waveguide.

[0014] Optionally, in the directional coupler tester, the waveguide switching component is disposed on one of the first waveguide and the second waveguide.

[0015] Optionally, in the directional coupler tester, at least one of the first waveguide and the second waveguide is a silicon waveguide or a silicon nitride waveguide.

[0016] Optionally, in the directional coupler tester, the multimode interferometer is a 1×2 multimode interferometer.

[0017] Optionally, in the directional coupler tester, at least one of the input optical coupler and the output optical coupler is a grating coupler or an end face coupler.

[0018] Optionally, in the directional coupler tester, the waveguide switching component is an adjustable optical attenuator.

[0019] A method for testing directional couplers, the method being used with any of the directional coupler testers described above, comprising:

[0020] Receive interference test command;

[0021] According to the interference test command, the waveguide switching component is controlled to make both the first waveguide and the second waveguide conduct, and the interference outgoing light signal is received from the outgoing light coupler;

[0022] Receive direct test commands;

[0023] According to the direct test command, control the waveguide switching component to make one of the first waveguide and the second waveguide conduct, and receive the direct emitted optical signal from the optical coupler;

[0024] The splitting ratio of the directional coupler to be measured is determined based on the direct emitted light signal and the interference emitted light signal.

[0025] Optionally, in the directional coupler testing method, the waveguide switching component is disposed on the first waveguide and the second waveguide;

[0026] According to the direct test command, controlling the waveguide switching component to make one of the first waveguide and the second waveguide conduct, and receiving the directly emitted optical signal from the optical coupler includes:

[0027] According to the direct test command, control the waveguide switching component to turn on the first waveguide and turn off the second waveguide, and receive the first direct emitted optical signal from the optical coupler;

[0028] According to the direct test command, control the waveguide switching component to turn on the second waveguide, turn off the first waveguide, and receive the second direct emitted optical signal from the optical coupler;

[0029] Accordingly, determining the splitting ratio of the directional coupler to be measured based on the directly emitted light signal and the interferometric emitted light signal includes:

[0030] The splitting ratio of the directional coupler to be measured is determined based on the first direct emitted light signal, the second direct emitted light signal, and the interference emitted light signal.

[0031] A directional coupler testing apparatus, the directional coupler testing apparatus being used for any of the directional coupler testers described above, comprising:

[0032] Interference receiving module, used to receive interference test commands;

[0033] The interference test module is used to control the waveguide switching component according to the interference test command, so that both the first waveguide and the second waveguide are turned on, and to receive the interference outgoing light signal from the outgoing light coupler;

[0034] The direct receiving module is used to receive direct test commands;

[0035] The direct test module is used to control the waveguide switching component according to the direct test command, so that one of the first waveguide and the second waveguide is turned on, and to receive the directly emitted optical signal from the optical coupler;

[0036] The splitting ratio module is used to determine the splitting ratio of the directional coupler to be measured based on the direct emitted light signal and the interference emitted light signal.

[0037] The directional coupler tester provided by this invention includes an input coupler, an output coupler, a first waveguide, a second waveguide, a multimode interferometer, and a waveguide switching component. The input coupler receives external test light and couples the test light into the multimode interferometer. The multimode interferometer splits the test light into a first test beam and a second test beam, and transmits the first test beam through the first waveguide to the first input port of the directional coupler to be tested, and the second test beam through the second waveguide to the second input port of the directional coupler to be tested. The first waveguide and the second waveguide have different lengths. The output coupler is disposed at the output port of the directional coupler to be tested. The waveguide switching component is disposed on at least one of the first waveguide and the second waveguide. This invention allows switching test modes by adjusting the waveguide switching component. When the waveguide switching component is controlled so that both the first and second waveguides are conducting, light enters through both inlets of the directional coupler under test, allowing for interferometric measurement of the splitting ratio. Conversely, the component can be controlled so that only one of the first and second waveguides is conducting, allowing light to enter through only one inlet of the directional coupler under test, allowing for direct measurement of the splitting ratio. This invention combines direct measurement and interferometric measurement within a single directional coupler test structure, avoiding the accuracy limitations that arise from creating multiple, less identical test structures for each method. In other words, this invention further improves the accuracy of directional coupler splitting ratio testing results. This invention also provides a directional coupler testing method and apparatus with the aforementioned beneficial effects. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of a directional coupler.

[0040] Figure 2 A schematic diagram of a specific embodiment of the directional coupler tester provided by the present invention;

[0041] Figure 3A schematic diagram of another specific embodiment of the directional coupler tester provided by the present invention;

[0042] Figure 4 A flowchart illustrating a specific implementation of the directional coupler testing method provided by the present invention;

[0043] Figure 5 This is a schematic diagram of a specific embodiment of the directional coupler testing device provided by the present invention.

[0044] The figure includes 10-input optical coupler, 20-output optical coupler, 41-first waveguide, 42-second waveguide, 30-multimode interferometer, 50-waveguide switching component, 100-interference receiving module, 200-interference testing module, 300-direct receiving module, 400-direct testing module, and 500-splitting ratio module. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] The core of this invention is to provide a directional coupler tester, the structural schematic diagram of one specific embodiment of which is shown below. Figure 2 As shown, this is referred to as Specific Implementation Method 1, which includes an input optical coupler 10, an output optical coupler 20, a first waveguide 41, a second waveguide 42, a multimode interferometer 30, and a waveguide switching component 50.

[0047] The optical coupler 10 is used to receive external test light and couple the test light into the multimode interferometer 30;

[0048] The multimode interferometer 30 is used to split the test beam into a first test beam and a second test beam, and to transmit the first test beam to the first light inlet of the directional coupler to be measured through the first waveguide 41, and to transmit the second test beam to the second light inlet of the directional coupler to be measured through the second waveguide 42.

[0049] The first waveguide 41 and the second waveguide 42 have different lengths;

[0050] The light output coupler 20 is disposed at the light output port of the direction coupler to be measured;

[0051] The waveguide switching component 50 is disposed on at least one of the first waveguide 41 and the second waveguide 42.

[0052] A schematic diagram of the directional coupler can be found by referring to... Figure 1 The directional coupler itself has two light inlets and two light outlets. For ease of description, the two light inlets are referred to as the first light inlet and the second light inlet, respectively. Since this invention does not make any improvement to the light outlet of the directional coupler, the term "light outlet" is used to refer to either of the two light outlets. Of course, when the waveguide switching component 50 is disposed on the first waveguide 41, the waveguide switching component 50 is used to control the switching on and off of the first waveguide 41; when the waveguide switching component 50 is disposed on the second waveguide 42, the waveguide switching component 50 is used to control the switching on and off of the second waveguide 42.

[0053] The specific length relationship between the first waveguide 41 and the second waveguide 42 is not limited in this invention. The first waveguide 41 may be longer than the second waveguide 42, or the second waveguide 42 may be longer than the first waveguide 41.

[0054] In one specific implementation, the waveguide switching component 50 is disposed on one of the first waveguide 41 and the second waveguide 42.

[0055] In other words, in this specific embodiment, the waveguide switching component 50 is only disposed on one of the first waveguide 41 and the second waveguide 42. Figure 2 The directional coupler is set on the first waveguide 41. Only one waveguide in the directional coupler can be controlled to open and close. In this way, only the waveguide switching component 50 needs to be closed to achieve the effect of only one light inlet receiving light, which means that direct measurement testing can be performed. On the other hand, only the waveguide switching component 50 needs to be opened to allow both light inlets to receive light, which means that interferometric measurement testing can be performed.

[0056] In addition, at least one of the first waveguide 41 and the second waveguide 42 is a silicon waveguide or a silicon nitride waveguide. Setting at least one of the first waveguide 41 and the second waveguide 42 as a silicon waveguide and / or a silicon nitride waveguide facilitates on-chip integration of the directional coupler tester and enables device miniaturization.

[0057] Furthermore, the multimode interferometer 30 is a 1×2 multimode interferometer 30. By placing a 1×2 multimode interferometer 30 at the light inlet of the directional coupler tester, compared to other types of multimode interferometers 30, the 1×2 multimode interferometer 30 exhibits more uniform beam splitting and more consistent energy and phase of the emitted beam, thereby further improving the accuracy of the interferometric measurement test results.

[0058] Furthermore, at least one of the input coupler 10 and the output coupler 20 is a grating coupler or an end-face coupler. In this preferred embodiment, the present invention provides two different couplers, namely the grating coupler and the end-face coupler. Both couplers can be used at the output port of the directional coupler as the output coupler 20, or at the input port of the directional coupler as the input coupler 10, greatly expanding the application scenarios of the present invention and improving its versatility.

[0059] In a preferred embodiment, the waveguide switching component 50 is an adjustable optical attenuator. The adjustable optical attenuator can quantitatively attenuate the power of the transmitted light, adapting to more application scenarios. Moreover, in the on (conducting) state, it has little impact on the original light transmission in the waveguide, improving the working stability of the device. Of course, other types of waveguide switching components 50 can also be selected, and this invention is not limited thereto.

[0060] The directional coupler tester provided by this invention includes an input coupler 10, an output coupler 20, a first waveguide 41, a second waveguide 42, a multimode interferometer 30, and a waveguide switching component 50. The input coupler 10 receives external test light and couples the test light into the multimode interferometer 30. The multimode interferometer 30 splits the test light into a first test beam and a second test beam, and transmits the first test beam through the first waveguide 41 to the first input port of the directional coupler to be tested, and transmits the second test beam through the second waveguide 42 to the second input port of the directional coupler to be tested. The first waveguide 41 and the second waveguide 42 have different lengths. The output coupler 20 is disposed at the output port of the directional coupler to be tested. The waveguide switching component 50 is disposed on at least one of the first waveguide 41 and the second waveguide 42. This invention allows switching test modes by adjusting the waveguide switching component 50. When the waveguide switching component 50 is controlled so that both the first waveguide 41 and the second waveguide 42 are conducting, light enters through both input ports of the directional coupler under test, allowing for interferometric measurement of the splitting ratio. Conversely, the waveguide switching component 50 can be controlled so that only one of the first waveguide 41 and the second waveguide 42 is conducting, allowing light to enter through only one input port of the directional coupler under test, allowing for direct measurement of the splitting ratio. This invention achieves a combination of direct measurement and interferometric measurement within the same directional coupler test structure, avoiding the accuracy limitations that can result from fabricating multiple, less identical test structures for separate direct and interferometric measurements. In other words, this invention further improves the accuracy of directional coupler splitting ratio test results.

[0061] Based on the above specific embodiments, the placement position of the waveguide switching component 50 is further limited to obtain a second specific embodiment, the corresponding structural diagram of which is shown below. Figure 3 As shown, it includes an input optical coupler 10, an output optical coupler 20, a first waveguide 41, a second waveguide 42, a multimode interferometer 30, and a waveguide switching component 50;

[0062] The optical coupler 10 is used to receive external test light and couple the test light into the multimode interferometer 30;

[0063] The multimode interferometer 30 is used to split the test beam into a first test beam and a second test beam, and to transmit the first test beam to the first light inlet of the directional coupler to be measured through the first waveguide 41, and to transmit the second test beam to the second light inlet of the directional coupler to be measured through the second waveguide 42.

[0064] The first waveguide 41 and the second waveguide 42 have different lengths;

[0065] The light output coupler 20 is disposed at the light output port of the direction coupler to be measured;

[0066] The waveguide switching component 50 is disposed on the first waveguide 41 and the second waveguide 42.

[0067] The difference between this specific embodiment and the above specific embodiment is that the waveguide switching component 50 is added to both waveguides in this specific embodiment. The rest of the structure is the same as the above specific embodiment, and will not be described in detail here.

[0068] In this specific embodiment, the waveguide switching component 50 is installed on both the first waveguide 41 and the second waveguide 42. Of course, when performing the direct measurement method test, it is only necessary to ensure that the two waveguides are on and off under the control of the waveguide switching component 50. It does not matter which of the first waveguide 41 and the second waveguide 42 is on or off.

[0069] On the one hand, installing the waveguide switching component 50 on both waveguides can effectively improve the working stability of the device and the accuracy of the measurement results. If one of the two waveguides fails, the waveguide switching component 50 can be used to directly shut down the faulty waveguide and use the other normal waveguide for direct measurement testing. On the other hand, even if both the first waveguide 41 and the second waveguide 42 are functioning properly, the result can be measured once through the first waveguide 41 and then once through the second waveguide 42 during the direct measurement test. The final result of the direct measurement test can then be obtained based on the results obtained from the two waveguide tests, further improving the measurement accuracy and working stability.

[0070] This invention also provides a method for testing directional couplers, the flowchart of one specific embodiment of which is shown below. Figure 4 As shown, referred to as Specific Implementation Method Three, the directional coupler testing method is used in any of the directional coupler testers described above, including:

[0071] S101: Receive interference test command.

[0072] S102: According to the interference test command, control the waveguide switching component 50 to make both the first waveguide 41 and the second waveguide 42 conduct, and receive the interference outgoing light signal from the outgoing light coupler 20.

[0073] S103: Receive direct test commands.

[0074] S104: According to the direct test command, control the waveguide switching component 50 to make one of the first waveguide 41 and the second waveguide 42 conduct, and receive the direct emitted optical signal from the optical coupler 20.

[0075] S105: Determine the splitting ratio of the directional coupler to be measured based on the direct emitted light signal and the interference emitted light signal.

[0076] It can be seen that steps S101 and S102 in the preceding text are interference testing processes, while steps S103 and S104 are direct testing processes. That is, the combination of S101 and S102 can be interchanged with the combination of S103 and S104 without affecting the final beam splitting ratio of the directional coupler to be measured.

[0077] The directional coupler testing method in this invention is applied to the directional coupler tester mentioned above. For specific technical details, please refer to the previous text. This invention will not repeat them here.

[0078] In a preferred embodiment, the waveguide switching component 50 is disposed on the first waveguide 41 and the second waveguide 42;

[0079] According to the direct test command, controlling the waveguide switching component 50 to make one of the first waveguide 41 and the second waveguide 42 conduct, and receiving the directly emitted optical signal from the optical coupler 20 includes:

[0080] A1: According to the direct test command, control the waveguide switching component 50 to turn on the first waveguide 41 and turn off the second waveguide 42, and receive the first direct emitted optical signal from the optical coupler 20.

[0081] A2: According to the direct test command, control the waveguide switching component 50 to turn on the second waveguide 42, turn off the first waveguide 41, and receive the second direct emitted optical signal from the optical coupler 20.

[0082] Accordingly, determining the splitting ratio of the directional coupler to be measured based on the directly emitted light signal and the interferometric emitted light signal includes:

[0083] A3: Determine the splitting ratio of the directional coupler to be measured based on the first direct emitted light signal, the second direct emitted light signal, and the interference emitted light signal.

[0084] In this preferred embodiment, two direct measurement tests were performed, each conducted through two different waveguides. The final test result of the direct measurement method for the directional coupler under test can be determined by combining the first and second directly emitted light signals. For example, the average of the first and second directly emitted light signals can be used as the final emitted light signal as the test result of the direct measurement method. Alternatively, if the difference between the first and second directly emitted light signals is too large, the first waveguide 41 and the second waveguide 42 of the directional coupler tester can be checked for faults.

[0085] The directional coupler testing method provided by this invention is used in any of the directional coupler testers described above, comprising: receiving an interference test command; controlling the waveguide switching component 50 according to the interference test command, so that both the first waveguide 41 and the second waveguide 42 are turned on, and receiving an interference emitted light signal from the output coupler 20; receiving a direct test command; controlling the waveguide switching component 50 according to the direct test command, so that one of the first waveguide 41 and the second waveguide 42 is turned on, and receiving a direct emitted light signal from the output coupler 20; and determining the splitting ratio of the directional coupler to be tested based on the direct emitted light signal and the interference emitted light signal. This invention allows switching test modes by adjusting the waveguide switching component 50. When the waveguide switching component 50 is controlled so that both the first waveguide 41 and the second waveguide 42 are conducting, light enters through both input ports of the directional coupler under test, allowing for interferometric measurement of the splitting ratio. Conversely, the waveguide switching component 50 can be controlled so that only one of the first waveguide 41 and the second waveguide 42 is conducting, allowing light to enter through only one input port of the directional coupler under test, allowing for direct measurement of the splitting ratio. This invention achieves a combination of direct measurement and interferometric measurement within the same directional coupler test structure, avoiding the accuracy limitations that can result from fabricating multiple, less identical test structures for separate direct and interferometric measurements. In other words, this invention further improves the accuracy of directional coupler splitting ratio test results.

[0086] The directional coupler testing device provided in the embodiments of the present invention will be described below. The directional coupler testing device described below can be referred to in correspondence with the directional coupler testing method described above.

[0087] Figure 5 This is a structural block diagram of the directional coupler testing device provided in an embodiment of the present invention, with reference to... Figure 5 A directional coupler testing apparatus for any of the directional coupler testers described above includes:

[0088] Interference receiving module 100 is used to receive interference test commands;

[0089] The interference test module 200 is used to control the waveguide switching component 50 according to the interference test command, so that both the first waveguide 41 and the second waveguide 42 are turned on, and to receive the interference emitted light signal from the output coupler 20.

[0090] The direct receiving module 300 is used to receive direct test commands;

[0091] The direct test module 400 is used to control the waveguide switching component 50 according to the direct test command, so that one of the first waveguide 41 and the second waveguide 42 is turned on, and to receive the direct emitted optical signal from the optical coupler 20.

[0092] The splitting ratio module 500 is used to determine the splitting ratio of the directional coupler to be measured based on the direct emitted light signal and the interference emitted light signal.

[0093] In a preferred embodiment, the waveguide switching component 50 is disposed on the first waveguide 41 and the second waveguide 42;

[0094] The interference testing module 200 includes:

[0095] The first waveguide 41 is a single-pass unit used to control the waveguide switching component 50 according to the direct test command, so that the first waveguide 41 is turned on, the second waveguide 42 is turned off, and the first direct emitted optical signal is received from the optical coupler 20.

[0096] The second waveguide 42 is a separate single-pass unit used to control the waveguide switching component 50 according to the direct test command, so that the second waveguide 42 is turned on, the first waveguide 41 is turned off, and the second direct emitted optical signal is received from the optical coupler 20.

[0097] The spectrophotometer module 500 includes:

[0098] The beam splitting ratio verification unit is used to determine the beam splitting ratio of the directional coupler to be measured based on the first direct emitted light signal, the second direct emitted light signal, and the interference emitted light signal.

[0099] The directional coupler testing device provided by the present invention includes an interference receiving module 100 for receiving interference test commands; an interference test module 200 for controlling the waveguide switching component 50 according to the interference test commands, so that both the first waveguide 41 and the second waveguide 42 are turned on, and receiving interference emitted light signals from the output coupler 20; a direct receiving module 300 for receiving direct test commands; a direct test module 400 for controlling the waveguide switching component 50 according to the direct test commands, so that one of the first waveguide 41 and the second waveguide 42 is turned on, and receiving direct emitted light signals from the output coupler 20; and a splitting ratio module 500 for determining the splitting ratio of the directional coupler to be tested according to the direct emitted light signals and the interference emitted light signals. This invention achieves a balance between direct measurement and interferometric measurement within the same test structure for a directional coupler, avoiding the upper limit on the accuracy of measurement results caused by fabricating multiple test structures with slightly different structures and performing direct and interferometric measurements separately. In other words, this invention further improves the accuracy of the directional coupler splitting ratio test results.

[0100] The directional coupler testing device of this embodiment is used to implement the aforementioned directional coupler testing method. Therefore, the specific implementation of the directional coupler testing device can be found in the embodiment section of the directional coupler testing method above. For example, the interference receiving module 100, the interference testing module 200, the direct receiving module 300, the direct testing module 400, and the splitting ratio module 500 are respectively used to implement steps S101, S102, S103, S104, and S105 in the above-mentioned directional coupler testing method. Therefore, its specific implementation can be referred to the description of the corresponding embodiments, which will not be repeated here.

[0101] The present invention also provides a directional coupler testing device, comprising:

[0102] Memory, used to store computer programs;

[0103] A processor is configured to execute the computer program to implement the steps of any of the above-described directional coupler testing methods. The directional coupler tester provided by this invention includes an input coupler 10, an output coupler 20, a first waveguide 41, a second waveguide 42, a multimode interferometer 30, and a waveguide switching component 50. The input coupler 10 receives external test light and couples the test light into the multimode interferometer 30. The multimode interferometer 30 splits the test light into a first test beam and a second test beam, and transmits the first test beam through the first waveguide 41 to the first input port of the directional coupler to be tested, and transmits the second test beam through the second waveguide 42 to the second input port of the directional coupler to be tested. The first waveguide 41 and the second waveguide 42 have different lengths. The output coupler 20 is disposed at the output port of the directional coupler to be tested. The waveguide switching component 50 is disposed on at least one of the first waveguide 41 and the second waveguide 42. This invention allows switching test modes by adjusting the waveguide switching component 50. When the waveguide switching component 50 is controlled so that both the first waveguide 41 and the second waveguide 42 are conducting, light enters through both input ports of the directional coupler under test, allowing for interferometric measurement of the splitting ratio. Conversely, the waveguide switching component 50 can be controlled so that only one of the first waveguide 41 and the second waveguide 42 is conducting, allowing light to enter through only one input port of the directional coupler under test, allowing for direct measurement of the splitting ratio. This invention achieves a combination of direct measurement and interferometric measurement within the same directional coupler test structure, avoiding the accuracy limitations that can result from fabricating multiple, less identical test structures for separate direct and interferometric measurements. In other words, this invention further improves the accuracy of directional coupler splitting ratio test results.

[0104] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the above-described directional coupler testing methods. The directional coupler tester provided by this invention includes an input coupler 10, an output coupler 20, a first waveguide 41, a second waveguide 42, a multimode interferometer 30, and a waveguide switching component 50. The input coupler 10 receives external test light and couples the test light into the multimode interferometer 30. The multimode interferometer 30 splits the test light into a first test beam and a second test beam, and transmits the first test beam through the first waveguide 41 to the first input port of the directional coupler to be tested, and transmits the second test beam through the second waveguide 42 to the second input port of the directional coupler to be tested. The first waveguide 41 and the second waveguide 42 have different lengths. The output coupler 20 is disposed at the output port of the directional coupler to be tested. The waveguide switching component 50 is disposed on at least one of the first waveguide 41 and the second waveguide 42. This invention allows switching test modes by adjusting the waveguide switching component 50. When the waveguide switching component 50 is controlled so that both the first waveguide 41 and the second waveguide 42 are conducting, light enters through both input ports of the directional coupler under test, allowing for interferometric measurement of the splitting ratio. Conversely, the waveguide switching component 50 can be controlled so that only one of the first waveguide 41 and the second waveguide 42 is conducting, allowing light to enter through only one input port of the directional coupler under test, allowing for direct measurement of the splitting ratio. This invention achieves a combination of direct measurement and interferometric measurement within the same directional coupler test structure, avoiding the accuracy limitations that can result from fabricating multiple, less identical test structures for separate direct and interferometric measurements. In other words, this invention further improves the accuracy of directional coupler splitting ratio test results.

[0105] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0106] It should be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0107] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0108] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0109] The directional coupler tester, its testing method, and apparatus provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of this invention.

Claims

1. A directional coupler tester characterized by, It includes an input optical coupler, an output optical coupler, a first waveguide, a second waveguide, a multimode interferometer, and a waveguide switching assembly; The optical coupler is used to receive external test light and couple the test light into the multimode interferometer; The multimode interferometer is used to split the test beam into a first test beam and a second test beam, and to transmit the first test beam to the first optical inlet of the directional coupler to be measured through the first waveguide, and to transmit the second test beam to the second optical inlet of the directional coupler to be measured through the second waveguide; The first waveguide and the second waveguide have different lengths; The light output coupler is disposed at the light output port of the direction coupler to be measured; The waveguide switching component is disposed on at least one of the first waveguide and the second waveguide.

2. The directional coupler tester of claim 1, wherein, The waveguide switching component is disposed on the first waveguide and the second waveguide.

3. The directional coupler tester of claim 1, wherein, The waveguide switching component is disposed on one of the first waveguide and the second waveguide.

4. The directional coupler tester of claim 1, wherein, At least one of the first waveguide and the second waveguide is a silicon waveguide or a silicon nitride waveguide.

5. The directional coupler tester of claim 1, wherein, The multimode interferometer is a 1×2 multimode interferometer.

6. The directional coupler tester of claim 1, wherein, At least one of the input optical coupler and the output optical coupler is a grating coupler or an end face coupler.

7. The directional coupler tester of any one of claims 1 to 6, wherein, The waveguide switching component is an adjustable optical attenuator.

8. A directional coupler testing method characterized by, The directional coupler testing method is used with the directional coupler tester as described in any one of claims 1, 4 to 7, comprising: Receive interference test command; According to the interference test command, the waveguide switching component is controlled to make both the first waveguide and the second waveguide conduct, and the interference outgoing light signal is received from the outgoing light coupler; Receive direct test commands; According to the direct test command, control the waveguide switching component to make one of the first waveguide and the second waveguide conduct, and receive the direct emitted optical signal from the optical coupler; The splitting ratio of the directional coupler to be measured is determined based on the direct emitted light signal and the interference emitted light signal.

9. The directional coupler test method of claim 8, wherein, The waveguide switching component is disposed on the first waveguide and the second waveguide; According to the direct test command, controlling the waveguide switching component to make one of the first waveguide and the second waveguide conduct, and receiving the directly emitted optical signal from the optical coupler includes: According to the direct test command, control the waveguide switching component to turn on the first waveguide and turn off the second waveguide, and receive the first direct emitted optical signal from the optical coupler; According to the direct test command, control the waveguide switching component to turn on the second waveguide, turn off the first waveguide, and receive the second direct emitted optical signal from the optical coupler; Accordingly, determining the splitting ratio of the directional coupler to be measured based on the directly emitted light signal and the interferometric emitted light signal includes: The splitting ratio of the directional coupler to be measured is determined based on the first direct emitted light signal, the second direct emitted light signal, and the interference emitted light signal.

10. A directional coupler test device characterized by, The directional coupler testing apparatus is used for the directional coupler tester as described in any one of claims 1 to 7, comprising: Interference receiving module, used to receive interference test commands; The interference test module is used to control the waveguide switching component according to the interference test command, so that both the first waveguide and the second waveguide are turned on, and to receive the interference outgoing light signal from the outgoing light coupler; The direct receiving module is used to receive direct test commands; The direct test module is used to control the waveguide switching component according to the direct test command, so that one of the first waveguide and the second waveguide is turned on, and to receive the directly emitted optical signal from the optical coupler; The splitting ratio module is used to determine the splitting ratio of the directional coupler to be measured based on the direct emitted light signal and the interference emitted light signal.

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