Optical module testing device and optical module testing system

Abstract

The invention relates to the field of optical module testing, and discloses an optical module testing device and an optical module testing system, and the device comprises a housing which is provided with an accommodation cavity; the printed circuit board is arranged in the shell, and a signal transmission interface connected with equipment to be tested is arranged on the printed circuit board; the printed circuit board comprises a first grounding layer, a second grounding layer, a first wiring layer and a second wiring layer; the signal switching module is arranged on the printed circuit board and connected with the signal transmission interface, the signal switching module is provided with a plurality of signal output channels, and when the signal switching module is triggered, the signal output by the equipment to be tested is output through one of the signal output channels; and the adapter is connected with the signal switching module, the adapter is used for being connected with a test display device, and the adapter is used for outputting the signal output by the to-be-tested device through the signal switching module to the test display device. The problem that a connecting device needs to be disassembled and replaced for multiple times when a test fixture performs a multi-module test is solved.

Description

Technical Field

[0001] This invention relates to the field of optical module testing, and more particularly to an optical module testing device and an optical module testing system. Background Technology

[0002] With the application of optical modules in high-speed data transmission, their electrical signal performance must meet compliance requirements regarding signal integrity (such as eye diagram, jitter, insertion loss, etc.). Therefore, conformance testing is a critical step before mass production of optical modules.

[0003] Existing test fixtures for testing optical module electrical interfaces fall into two categories: The first uses a circuit board design with two layers: a two-layer circuit board, optical module gold fingers, adapters, and the optical module housing. The wiring includes four pairs of differential lines (TX) and four pairs of differential lines (RX), connected from the gold fingers to the adapters. Multiple adapters are placed on both sides of the circuit board for interconnection (each adapter corresponds to a signal line connection at the end). The second type uses an optical module gold finger, adapter, and cable design; wiring from the gold fingers leads to the adapters and cables at the ends.

[0004] The aforementioned test fixture, serving as the core bridge connecting the module under test and the test instrument, has the following technical drawbacks: frequent disassembly and assembly of adapters and cables can easily cause interface wear and poor contact, increasing test errors and equipment wear; furthermore, switching between multiple signal channels requires repeated disassembly and replacement, leading to a longer test cycle. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide an optical module testing device and an optical module testing system to solve the problem that the test fixture needs to be disassembled and replaced multiple times when performing multi-module testing.

[0006] The technical solution of the present invention is as follows: An optical module testing device, comprising: The shell has a accommodating cavity; A printed circuit board (PCB) is disposed within the housing. The PCB has a signal transmission interface for connecting the device under test (DUT). The PCB includes a first ground layer, a second ground layer, a first wiring layer, and a second wiring layer. The first wiring layer and the second wiring layer are disposed sequentially from top to bottom between the first ground layer and the second ground layer. Shielding strips are provided on both sides of the first wiring layer and the second wiring layer. The shielding strips are connected to the first ground layer and the second ground layer through return ground vias. Only the differential line routing area is reserved in the first wiring layer and the second wiring layer, and the remaining areas are covered with ground copper foil and return ground vias. A signal switching module is disposed on the printed circuit board. The signal switching module is connected to the signal transmission interface through a signal line. The signal switching module has multiple signal output channels. When triggered, the signal switching module is used to output the signal output by the device under test through one of the multiple signal output channels. An adapter is disposed on the printed circuit board. The adapter is connected to the signal switching module. The adapter is used to connect to the test display device and to output the signal output by the device under test through the signal switching module to the test display device.

[0007] Optionally, the signal switching module includes: A toggle switch includes multiple input interfaces and one output interface. The multiple input interfaces are connected to the signal transmission interface via signal lines, and the output interface is connected to the adapter via signal lines. The toggle switch is used to connect one of the multiple input interfaces to the output interface when triggered.

[0008] Optionally, the housing is a convex frame, which includes a protruding portion and a main body portion. The protruding portion of the housing is used to accommodate the signal transmission interface, and the main body portion of the housing is used to accommodate the printed circuit board. The inner side of the main body portion of the housing is provided with a slot that matches the printed circuit board.

[0009] Optionally, the optical module testing device further includes: A shielding layer is disposed on the inner side of the main body of the housing. The shielding layer is matched with the printed circuit board and is used to shield external electromagnetic interference signals.

[0010] Optionally, the printed circuit board includes a first ground layer, a second ground layer, a first wiring layer, and a second wiring layer. The first wiring layer and the second wiring layer are disposed between the first ground layer and the second ground layer from top to bottom. Shielding strips are provided on both sides of the first wiring layer and the second wiring layer. The shielding strips are connected to the first ground layer and the second ground layer through return ground vias.

[0011] Optionally, the signal transmission interface includes a power supply pin, a ground pin, and a signal terminal. The power supply pin is connected to the first ground layer, the ground pin is connected to the second ground layer, and the signal terminal is connected to the first wiring layer and the second wiring layer.

[0012] Optionally, the printed circuit board further includes: The first pad is located in the middle of the printed circuit board. The first pad is connected to the first ground layer and the second ground layer through a first via. The first pad is used to solder the signal switching module. The second pad is disposed on the edge of the printed circuit board. The second pad is connected to the first ground layer and the second ground layer through a second via. The second pad is used to solder the adapter.

[0013] Optionally, the optical module testing device further includes: An input differential line is disposed on the first wiring layer and the second wiring layer, and the input differential line is used to connect the signal transmission interface and the signal switching module; The output differential lines are disposed on the first wiring layer and the second wiring layer, and the output differential lines are used to connect the signal switching module and the adapter.

[0014] Optionally, the optical module testing device is used to test optical modules of model QSFP28 or QSFP56.

[0015] The present invention also proposes an optical module testing system, including a device under test, a test display device, and an optical module testing apparatus as described above. The device under test is connected to the signal transmission interface in the optical module testing apparatus, and the test display device is connected to the adapter in the optical module testing apparatus.

[0016] This invention provides an optical module testing device comprising a housing, a printed circuit board, a signal switching module, and an adapter. The housing has a cavity; the printed circuit board has a signal transmission interface for connecting the device under test (DUT); the signal switching module connects to the signal transmission interface via signal lines and has multiple signal output channels. When triggered, the signal switching module outputs the signal from the DUT through one of these channels; the adapter connects to the signal switching module and is used to connect to a test display device, transmitting the signal from the DUT via the signal switching module to the test display device. Thus, this optical module testing device can access one of the multiple signals from the DUT by triggering the signal switching module, eliminating the need for frequent disassembly of the adapter and cables, reducing wear, preventing signal attenuation, and shortening the testing cycle. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in 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 the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a functional module schematic diagram of an embodiment of the optical module testing device of the present invention.

[0019] Figure 2 This is a schematic diagram of an embodiment of the optical module testing device of the present invention.

[0020] Figure 3 This is a schematic diagram of an embodiment of the first ground layer of the printed circuit board in the optical module testing device of the present invention.

[0021] Figure 4 This is a schematic diagram of an embodiment of the first wiring layer of the printed circuit board in the optical module testing device of the present invention.

[0022] Figure 5 This is a schematic diagram of another embodiment of the optical module testing device of the present invention.

[0023] Explanation of reference numerals in the attached drawings: 10, housing; 20, printed circuit board; 30, signal transmission interface; 40, signal switching module; 50, adapter. Detailed Implementation

[0024] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] In the implementation methods and claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of the present invention involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0026] It should be further understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0027] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0028] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0029] With the application of optical modules in high-speed data transmission, their electrical signal performance must meet compliance requirements regarding signal integrity (such as eye diagram, jitter, insertion loss, etc.). Therefore, conformance testing is a critical step before mass production of optical modules.

[0030] Existing test fixtures for testing optical module electrical interfaces fall into two categories: The first uses a circuit board design with two layers: a two-layer circuit board, optical module gold fingers, adapters, and the optical module housing. The wiring includes four pairs of differential lines (TX) and four pairs of differential lines (RX), connected from the gold fingers to the adapters. Multiple adapters are placed on both sides of the circuit board for interconnection (each adapter corresponds to a signal line connection at the end). The second type uses an optical module gold finger, adapter, and cable design; wiring from the gold fingers leads to the adapters and cables at the ends.

[0031] The aforementioned test fixture, serving as the core bridge connecting the module under test and the test instrument, has the following technical drawbacks: frequent disassembly and assembly of adapters and cables can easily cause interface wear and poor contact, increasing test errors and equipment wear; furthermore, switching between multiple signal channels requires repeated disassembly and replacement, leading to a longer test cycle.

[0032] To address the above problems, this invention proposes an optical module testing device.

[0033] Reference Figure 1 In one embodiment, the optical module testing apparatus includes: The shell 10 has a receiving cavity; A printed circuit board 20 is disposed within the housing 10. The printed circuit board 20 is provided with a signal transmission interface 30 for connecting the device under test. The printed circuit board 20 includes a first ground layer, a second ground layer, a first wiring layer, and a second wiring layer. The first wiring layer and the second wiring layer are disposed sequentially from top to bottom between the first ground layer and the second ground layer. Shielding strips are provided on both sides of the first wiring layer and the second wiring layer. The shielding strips are connected to the first ground layer and the second ground layer through return ground vias. Only the differential line routing area is reserved in the first wiring layer and the second wiring layer, and the remaining areas are covered with ground copper foil and return ground vias. A signal switching module 40 is disposed on the printed circuit board 20. The signal switching module 40 is connected to the signal transmission interface 30 through a signal line. The signal switching module 40 has multiple signal output channels. When triggered, the signal switching module 40 outputs the signal output by the device under test through one of the multiple signal output channels. An adapter 50 is disposed on the printed circuit board 20. The adapter 50 is connected to the signal switching module 40. The adapter 50 is used to connect to the test display device and to output the signal output by the device under test through the signal switching module 40 to the test display device.

[0034] In this embodiment, the housing 10 is used to fix the positional relationship of various components on the optical module testing device, ensuring the safety and stability of the cavity formed by the housing 10. The housing 10 also protects the internal components from external environmental influences such as dust, moisture, chemicals, and physical impacts. The printed circuit board 20 is the basic structure for connecting electronic components. The printed circuit board 20 can be made of insulating material (such as epoxy resin or fiberglass) with conductive lines printed on its surface to form a circuit. The signal transmission interface 30 on the printed circuit board 20 connecting the device under test (DUT) can be a gold finger. The gold finger is a metal contact point connecting the DUT and the printed circuit board 20. Gold plating ensures good conductivity and corrosion resistance. During testing, the optical module testing device sends various test signals, such as electrical signals and control signals, to the DUT through the gold finger. Simultaneously, the DUT also transmits feedback signals back to the optical module testing device through the gold finger. The optical module testing device then outputs the signals to a test display device, such as an oscilloscope. Users can directly see the signal test results through the test display device, thereby evaluating the performance of the optical module. The device under test can be a different type of optical module, and different types of optical modules require corresponding gold finger connection contacts. In this embodiment, the printed circuit board 20 can adopt a stacked structure, specifically four layers (100mm×50mm in size), with ultra-low loss material as the interlayer dielectric. For example, the four layers are a first ground layer, a second ground layer, a first wiring layer, and a second wiring layer. The interlayer thickness is controlled as follows: the first ground layer is 0.2mm thicker than the first wiring layer, the first wiring layer is 0.4mm thicker than the second wiring layer, and the second wiring layer is 0.2mm thicker than the second ground layer. The thickness is mainly used to control impedance, and the final design needs to be adjusted according to the actual situation. Furthermore, the first and second ground layers are fully copper-covered as ground planes with a copper thickness of 1oz (35μm) and the surface is gold-plated (0.05μm thick) to ensure grounding continuity. The first and second wiring layers only retain differential line routing areas, and the remaining areas are covered with ground copper foil and return ground vias. Shielding strips (width ≥ 3 times the line width) are provided on both sides of the first and second wiring layers. The shielding strips are connected to the first and second ground layers through return ground vias (spacing ≤ 10 mm, via diameter 0.3 mm) to form a “signal-ground” encircling structure, which can reduce crosstalk. The routing area design and return ground vias in this embodiment can increase anti-interference capability.

[0035] Understandably, to address the aforementioned issues, this solution incorporates a signal switching module 40. The multiple signal output channels of the signal switching module 40 can connect to multiple signals from the device under test (DUT). By triggering the signal switching module 40, one of its multiple signal output channels is activated, thereby connecting one signal from the DUT. Compared to traditional solutions where a single interface corresponds to a single signal channel, this optical module testing device eliminates the need for frequent disassembly and reassembly of the adapter 50 and cables, reducing wear, preventing signal attenuation, and shortening the testing cycle.

[0036] Adapter 50 is an RF connector that connects two different types of devices. Adapter 50 can be made of copper or brass and plated with gold or nickel to improve conductivity and corrosion resistance. For example, adapter 50 can be a high-precision SMA-K type adapter with a characteristic impedance of 50Ω, an operating frequency range of DC-40GHz, and an M5×0.8 interface thread. It can be connected to the printed circuit board 20 via reflow soldering to ensure mechanical strength.

[0037] The present invention provides an optical module testing device comprising a housing 10, a printed circuit board 20, a signal switching module 40, and an adapter 50. The housing 10 has a receiving cavity. The printed circuit board 20 has a signal transmission interface 30 for connecting to the device under test (DUT). The signal switching module 40 is connected to the signal transmission interface 30 via a signal line and has multiple signal output channels. When triggered, the signal switching module 40 outputs the signal from the DUT through one of these channels. The adapter 50 is connected to the signal switching module 40 and is used to connect to a test display device. The adapter 50 outputs the signal from the DUT through the signal switching module 40 to the test display device. Thus, the optical module testing device of this invention can access one of the multiple signals output by the DUT by triggering the signal switching module 40, eliminating the need for frequent disassembly and reassembly of the adapter 50 and cables, reducing wear, preventing signal attenuation, and shortening the testing cycle.

[0038] Reference Figure 2 In one embodiment, the signal switching module 40 includes: A toggle switch includes multiple input interfaces and one output interface. The multiple input interfaces are connected to the signal transmission interface 30 via signal lines, and the output interface is connected to the adapter 50 via signal lines. The toggle switch is used to connect one of the multiple input interfaces to the output interface when triggered.

[0039] In this embodiment, the signal switching module 40 can be a toggle switch, such as a 4-channel mechanical toggle switch, including 4 sets of input interfaces (corresponding to 4 pairs of TX / RX differential lines) and 1 set of output interfaces (corresponding to 1 pair of output differential lines). The internal contacts of the switch are gold-plated (0.5μm thick), and the contact resistance is ≤50mΩ. The specific number of channels can be set according to the actual situation and user needs. The switching mechanism is achieved by manually toggling the switch position (e.g., 0-3) to switch the 4 pairs of input signals: when switched to "0", the first pair of differential lines is connected to the output line; when switched to "1", the second pair of differential lines is connected to the output line, and so on, ensuring that only 1 pair of differential lines is connected to the adapter 50 through the output line each time. In this way, the test time for 4 pairs of signal channels of a device under test is reduced from 10 minutes in the traditional solution to 2 minutes. The mechanical switching mechanism eliminates the need to repeatedly disassemble the adapter 50 and cables, and the switching time of a single signal channel is reduced from 2 minutes in the traditional solution to 5 seconds. In this embodiment, a toggle switch is used to better switch channels for high-speed differential electrical signals (25Gbps and above). In specific applications, other devices with similar functions to the toggle switch can also be selected according to actual conditions and user needs.

[0040] Reference Figure 5 In another embodiment, a jumper cap solution can be used instead of a toggle switch solution. Switching tests are performed by manually changing the jumper cap connection to each signal channel, eliminating the need for frequent disassembly and reassembly of cables and adapters 50. This also achieves the effect of switching multiple signal channels.

[0041] Reference Figure 2 In one embodiment, the housing 10 is a convex frame, which includes a protruding portion and a main body portion. The protruding portion of the housing 10 is used to accommodate the signal transmission interface 30, and the main body portion of the housing 10 is used to accommodate the printed circuit board 20. A slot matching the printed circuit board 20 is provided on the inner side of the main body portion of the housing 10.

[0042] In this embodiment, the housing 10 is configured as a convex frame to accommodate the printed circuit board 20 and the signal transmission interface 30. Since the signal transmission interface 30 is mounted on the printed circuit board 20 and is an integral structure, the printed circuit board 20 has a convex structure overall. Therefore, the housing 10 is designed as a convex frame to accommodate the printed circuit board 20. The specific frame dimensions can be designed according to the dimensions of the signal transmission interface 30 and the printed circuit board 20. Specifically, the housing 10 can be made of 1.2mm thick aluminum alloy, with an overall "convex frame + top cover" structure. The inner side of the main body of the housing 10 frame has a slot (tolerance ±0.05mm) that matches the edge of the printed circuit board 20. It is fixed to the printed circuit board 20 by four M2 screws. The M2 screw settings can be referenced... Figure 2The top cover is the slot above the entire signal transmission interface 30. The specific thickness of the housing 10 can also be set according to actual conditions and user needs. The slots on the inner side of the main body of the housing 10 that match the printed circuit board 20 can be referred to... Figure 2 70.

[0043] It is understandable that high-speed signals (data transmission rate ≥ 25Gbps) are susceptible to external electromagnetic interference and crosstalk during transmission, which can lead to deviations in test results.

[0044] Therefore, in one embodiment, the optical module testing device further includes: A shielding layer is disposed on the inner side of the main body of the housing 10. The shielding layer is matched with the printed circuit board 20 and is used to shield external electromagnetic interference signals.

[0045] In this embodiment, the shielding layer is a 3μm thick nickel-gold layer electroplated on the inner side of the main body of the housing 10 frame. The shielding layer is shaped to match the printed circuit board 20. The shielding layer can wrap the printed circuit board 20 to form an electromagnetic shielding cavity (shielding effectiveness ≥60dB@1-10GHz), which can isolate the influence of external electromagnetic interference on high-speed signals. The specific thickness can also be set according to actual conditions and user needs. In addition to the nickel-gold layer, other materials that meet shielding performance can also be used for the shielding layer. Compared with the traditional "separate fixed + independent shielding" design, where the outer shell only plays a fixed support role, this embodiment integrates the mechanical support and electromagnetic shielding functions of the housing 10 and the printed circuit board 20. The inner side of the housing 10 is electroplated with a nickel-gold layer to form a closed shielding cavity, which isolates the influence of external electromagnetic interference on high-speed signals and can solve the problem of result deviation caused by noise interference in the test environment.

[0046] Furthermore, in one embodiment, the signal transmission interface 30 includes a power supply pin, a ground pin, and a signal terminal. The power supply pin is connected to the first ground layer, the ground pin is connected to the second ground layer, and the signal terminal is connected to the first wiring layer and the second wiring layer.

[0047] The printed circuit board 20 also includes: The first pad is located in the middle of the printed circuit board 20. The first pad is connected to the first ground layer and the second ground layer through the first via. The first pad is used to solder the signal switching module 40. The second pad is disposed on the edge of the printed circuit board 20. The second pad is connected to the first ground layer and the second ground layer through a second via. The second pad is used to solder the adapter 50.

[0048] In this embodiment, the signal transmission interface 30 is described using a gold finger as an example. This embodiment uses a QSFP standard gold finger (compliant with SFF-8636 specification), with a total of 38 pins. The power supply pins and ground pins are directly connected to the first ground layer and the second ground layer, respectively. The signal pins are connected to the differential lines of the first wiring layer and the second wiring layer, respectively. The first pad can reserve 8 groups of 2.54mm pitch pads (16 pins in total) in the middle of the printed circuit board 20. The first and second ground layers of the printed circuit board 20 are designed symmetrically, and are used to solder the signal switching module 40. The first pad is connected to the first and second ground layers through a first via (0.3mm diameter) to ensure reliable grounding. The second pad can reserve 2 groups of 50Ω pads (center pin diameter 0.8mm, grounding ring diameter 3mm) at the edge of the printed circuit board 20. The first and second ground layers of the printed circuit board 20 are designed symmetrically, and the second pad is connected to the first and second ground layers through a second via to reduce impedance abrupt changes. For details on the configuration of the signal switching module 40 and the adapter 50 on the first ground plane, please refer to [reference needed]. Figure 3 .

[0049] Reference Figure 2 In one embodiment, the optical module testing device further includes: An input differential line is disposed on the first wiring layer and the second wiring layer, and the input differential line is used to connect the signal transmission interface 30 and the signal switching module 40; Output differential lines are disposed on the first wiring layer and the second wiring layer, and the output differential lines are used to connect the signal switching module 40 and the adapter 50.

[0050] In this embodiment, the input differential line can be composed of 4 pairs of TX differential lines and 4 pairs of RX differential lines. Each pair of differential lines has an impedance of 100Ω ± 10% and a line length error of ≤ 5mm. The TX differential lines are disposed on the first wiring layer of the printed circuit board 20. After being led out from the signal pins of the gold fingers, they are all routed on the first wiring layer and connected to the first pad on the first ground layer. For details, please refer to... Figure 4TX_lane0, TX_lane1, TX_lane2, and TX_lane3 represent four pairs of TX differential lines. The RX differential lines are located on the second wiring layer of the printed circuit board 20. After being led out from the signal pins of the gold fingers, they are all routed on the second wiring layer and connected to the second pad on the second ground layer. The RX differential line configuration can refer to the TX differential line configuration. It should be noted that in this embodiment, the RX signal differential lines can be mirrored in the TX design (TX is located on the first ground layer and the first wiring layer, and RX is located on the second wiring layer and the second ground layer). This requires two toggle switches (4 inputs and 1 output) and four adapters, symmetrically placed on the first and second ground layers respectively. The output differential lines are led out from the first pad as a pair of differential lines, routed mixed on the first and second wiring layers (selecting the corresponding layer according to the switched signal channel), and finally connected to the second pad. The trace length is controlled within 50mm (to reduce high-frequency loss). For details, please refer to... Figure 4 Where lane represents the output differential line. In this embodiment, the differential line impedance is controlled at 100Ω±10% (verified by simulation / testing with line width / spacing: line width 0.25mm, line spacing 0.3mm), which can reduce signal reflection.

[0051] Furthermore, in another embodiment, the printed circuit board can employ a two-layer design for testing the TX signal. The two-layer design means that only the TX signal is present, with the traces routed on the first layer. A toggle switch (4 inputs, 1 output) and two adapters are also located on the first layer. For details, please refer to [reference needed]. Figure 2 The second layer is entirely ground plane. In the above embodiment, the four-layer design of the printed circuit board is used to test the TX and RX signals. This is a compliance test for the RX signal in the Ethernet protocol, primarily testing the bit error rate (BER) of the loopback. The TX compliance test mainly measures requirements such as eye diagram jitter. The test display equipment used for the two is also different: an oscilloscope is used for the TX signal, and a bit error rate tester is used for the RX signal. Furthermore, the testing is performed separately and independently using either an oscilloscope or a bit error rate tester. The four-layer design of the printed circuit board, with the TX and RX signals connected to their own independent toggle switches and adapters, offers better signal integrity. A two-layer design of the printed circuit board is simpler in structure and more efficient in testing. Specific printed circuit boards can be designed according to actual conditions and user requirements.

[0052] In one embodiment, the optical module testing device is used to test optical modules of model QSFP28 or QSFP56.

[0053] In this embodiment, the optical modules under test, specifically the QSFP28 and QSFP56 models, are four-channel optical modules, characterized by their small size and high density, making them suitable for high-speed data transmission applications. The optical module testing device in this solution is a verification fixture for the electrical signals of QSFP28 or QSFP56 models. Other models, such as SFP / SFP+ / XFP / QSFPDD, differ mainly in the pin design of the gold fingers; therefore, this optical module testing device is not a universal testing device for all models. This is because the number of pins on the gold fingers differs—for example, QSFP28 has 38 pins, while SFP+ has only 20—and the structural dimensions also differ. It should be noted that the differential line impedance design requirements differ for different interfaces. In this embodiment, the electrical signals of the QSFP28 optical module are generally controlled between 90 and 100 ohms impedance.

[0054] This invention also proposes an optical module testing system.

[0055] In one embodiment, the optical module testing system includes a device under test (DUT), a test display device, and an optical module testing apparatus as described above. The DUT is connected to the signal transmission interface 30 in the optical module testing apparatus, and the test display device is connected to the adapter 50 in the optical module testing apparatus. In this embodiment, the overall testing process of the optical module testing system of the present invention is as follows: First, the DUT is powered on and enters the compliance test mode, sending the corresponding pseudo-random code signal according to the IEEE (Institute of Electrical and Electronics Engineers) 802.3 protocol. The signal transmission interface 30 of the optical module testing apparatus is inserted into the DUT, and the toggle switch is set to position 0, corresponding to the first signal channel. The adapter 50 of the optical module testing apparatus is connected to the test display device via a cable. The test display device can be an oscilloscope, etc., so that testing can be performed on the oscilloscope and a compliance report can be output. Then, the toggle switch is switched to position 1, corresponding to the second signal channel, and so on, until the testing of all four signal channels of one DUT is completed. The optical module testing device is then plugged in and unplugged to test the next device under test (DUT), and so on. This allows multiple DUTs to be tested. Furthermore, when testing a single DUT, it is not necessary to disassemble multiple signal channels, reducing interface wear and shortening the testing time for a single DUT.

[0056] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An optical module testing device, characterized in that, include: The shell has a accommodating cavity; A printed circuit board (PCB) is disposed within the housing. The PCB has a signal transmission interface for connecting the device under test (DUT). The PCB includes a first ground layer, a second ground layer, a first wiring layer, and a second wiring layer. The first wiring layer and the second wiring layer are disposed sequentially from top to bottom between the first ground layer and the second ground layer. Shielding strips are provided on both sides of the first wiring layer and the second wiring layer. The shielding strips are connected to the first ground layer and the second ground layer through return ground vias. Only the differential line routing area is reserved in the first wiring layer and the second wiring layer, and the remaining areas are covered with ground copper foil and return ground vias. A signal switching module is disposed on the printed circuit board. The signal switching module is connected to the signal transmission interface through a signal line. The signal switching module has multiple signal output channels. When triggered, the signal switching module is used to output the signal output by the device under test through one of the multiple signal output channels. An adapter is disposed on the printed circuit board. The adapter is connected to the signal switching module. The adapter is used to connect to the test display device and to output the signal output by the device under test through the signal switching module to the test display device.

2. The optical module testing device as described in claim 1, characterized in that, The signal switching module includes: A toggle switch includes multiple input interfaces and one output interface. The multiple input interfaces are connected to the signal transmission interface via signal lines, and the output interface is connected to the adapter via signal lines. The toggle switch is used to connect one of the multiple input interfaces to the output interface when triggered.

3. The optical module testing device as described in claim 1, characterized in that, The housing is a convex frame, which includes a protruding part and a main body. The protruding part of the housing is used to accommodate the signal transmission interface, and the main body of the housing is used to accommodate the printed circuit board. The inner side of the main body of the housing is provided with a slot that matches the printed circuit board.

4. The optical module testing device as described in claim 3, characterized in that, The optical module testing device also includes: A shielding layer is disposed on the inner side of the main body of the housing. The shielding layer is matched with the printed circuit board and is used to shield external electromagnetic interference signals.

5. The optical module testing device as described in claim 1, characterized in that, The signal transmission interface includes a power pin, a ground pin, and a signal terminal. The power pin is connected to the first ground layer, the ground pin is connected to the second ground layer, and the signal terminal is connected to the first wiring layer and the second wiring layer.

6. The optical module testing device as described in claim 1, characterized in that, The printed circuit board also includes: The first pad is located in the middle of the printed circuit board. The first pad is connected to the first ground layer and the second ground layer through a first via. The first pad is used to solder the signal switching module. The second pad is disposed on the edge of the printed circuit board. The second pad is connected to the first ground layer and the second ground layer through a second via. The second pad is used to solder the adapter.

7. The optical module testing device as described in claim 1, characterized in that, The optical module testing device also includes: An input differential line is disposed on the first wiring layer and the second wiring layer, and the input differential line is used to connect the signal transmission interface and the signal switching module; The output differential lines are disposed on the first wiring layer and the second wiring layer, and the output differential lines are used to connect the signal switching module and the adapter.

8. The optical module testing device as described in claim 1, characterized in that, The optical module testing device is used to test optical modules of model QSFP28 or QSFP56.

9. An optical module testing system, characterized in that, It includes a device under test, a test display device, and an optical module test apparatus as described in any one of claims 1-8, wherein the device under test is connected to the signal transmission interface in the optical module test apparatus, and the test display device is connected to the adapter in the optical module test apparatus.

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