An optical time-domain reflectometer, a signal generation method, an apparatus, a device, and a medium.

Abstract

This application relates to an optical time-domain reflectometer, a signal generation method, apparatus, device, and medium, comprising a laser, a first optical switch, an EDFA amplifier, and a second optical switch connected in sequence. A timing control unit controls the first and second optical switches to periodically open and close to form periodic optical pulse signals. Within one cycle, the second optical switch opens and closes with a delay relative to the first optical switch, and this delayed opening and closing control generates the required pulse width. When the optical signal is normally output in the current cycle, erbium ions excited by the pump light of the EDFA amplifier amplify the signal light. If the input light is cut off, the metastable erbium ions continue to accumulate to a saturation state. When the signal light input is restored in the next cycle, an energy jump occurs, causing an optical surge. The output optical power increases instantaneously, increasing the pulse peak value, thereby improving the dynamic range of the optical time-domain reflectometer and enabling the detection of hollow-core optical fibers.

Description

Technical Field

[0001] This application relates to the field of optical fiber detection technology, and in particular to a signal generation method and its optical time domain reflectometer. Background Technology

[0002] In recent years, with the rapid development of anti-resonant hollow fiber technology, its advantages of low latency, low nonlinearity, and low loss have attracted widespread attention from the optical fiber communication industry and academia, leading to extensive research. Currently, commercially available optical fiber transmission systems are mainly built based on traditional single-mode fibers, with an internal optical signal transmission speed of approximately 2 × 10⁻⁶. 8 Its transmission speed is m / s, and its latency is greater than that of air. Furthermore, due to the high temperature sensitivity of glass, its transmission latency varies significantly with temperature. Its core is solid silicon dioxide (refractive index approximately 1.44), and its backscattering coefficient is typically around -72 dB / m. Hollow-core optical fiber, on the other hand, has an air core (refractive index approximately 1.003), and its internal optical signal transmission speed is approximately 3 × 10⁻⁶ m / s. 8 Compared to traditional single-mode fiber, hollow-core fiber offers a propagation speed of up to 46% higher and a latency reduction of 30%, with approximately 20 times better temperature stability. It also exhibits about 30 dB lower backscattering than traditional single-mode fiber, along with ultra-low nonlinearity and an ultra-wide wavelength range. These advantages mean that higher input power can be used when using hollow-core fiber, allowing for increased fiber optic transmission spans, reducing the number of optical amplification nodes in long-distance transmission, significantly simplifying fiber optic link structure, and lowering network operating power consumption and construction costs. Therefore, future transmission systems based on hollow-core fiber will possess numerous advantages.

[0003] For testing ordinary single-mode optical fibers, optical time-domain reflectometry (OTDR) is generally used. It measures the transmission characteristics of optical fibers based on the backscattering of the silica fiber core and is widely used in the construction and maintenance of optical fibers. However, since the backscattering of hollow fiber is about 30dB lower than that of traditional single-mode fiber, it is not applicable to commercially available OTDRs. Summary of the Invention

[0004] This application provides an optical time domain reflectometer, a signal generation method, an apparatus, a device, and a medium to solve the problem in the related art that current optical time domain reflectometers cannot be used with hollow optical fibers that have a backscattering rate of about 30 dB lower than that of traditional single-mode optical fibers.

[0005] In a first aspect, an optical time-domain reflectometer is provided, comprising: a laser, a first optical switch, an EDFA amplifier, and a second optical switch connected in sequence;

[0006] The first optical switch and the second optical switch are connected to an optical switch timing control unit; the optical switch timing control unit is used to control the first optical switch and the second optical switch to periodically turn on and off to form periodic optical pulse signals;

[0007] In one cycle, the second optical switch is delayed in opening and delayed in closing relative to the first optical switch.

[0008] In some embodiments, the optical switch timing control unit is further configured to adjust a first delay time for the second optical switch to turn on relative to the first optical switch within a cycle.

[0009] In some embodiments, the optical time domain reflectometer further includes a fiber optic link component under test and an optical signal receiving component;

[0010] The fiber optic link component under test is connected to the optical output end of the second optical switch and is used to connect to the fiber optic link under test.

[0011] The optical signal receiving component is connected to the fiber optic link component under test and is used to receive and detect the backscattered optical signal returned by the fiber optic link component under test, and to plot the backscattering curve.

[0012] In some embodiments, the fiber optic link assembly under test includes an optical circulator connected to the optical output end of the second optical switch, and the detection end of the optical circulator is connected to a fiber optic link, which is used to send the periodic optical pulse signal output by the second optical switch to the fiber optic link under test.

[0013] The optical signal receiving component includes a detector and a signal analysis unit; the signal receiving end of the optical circulator is connected to the detector, and the output end of the detector is connected to the signal analysis unit.

[0014] The detector is used to output an electrical signal based on the received backscattered light signal; the signal analysis unit is used to plot the backscattering curve of the electrical signal; the backscattered light signal is generated by the interaction of a periodic light pulse signal with the optical fiber under test.

[0015] In some embodiments, a first coupler is provided between the laser and the first optical switch;

[0016] A second coupler is provided between the signal receiving end of the detector and the optical circulator; the first coupler and the second coupler are connected to send part of the laser light to the input end of the second coupler.

[0017] Secondly, a signal generation method is provided, which is applied to an optical time-domain reflectometer, including:

[0018] Turn off the first and second optical switches and turn on the EDFA amplifier;

[0019] The first optical switch and the second optical switch are controlled to periodically turn on and off to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch is controlled to turn on and off with a delay relative to the first optical switch.

[0020] In some embodiments, controlling the second optical switch to turn on and off with a delay relative to the first optical switch within a cycle includes the following steps:

[0021] Control the first optical switch to open and maintain it for a first duration, and input the optical signal from the laser into the EDFA amplifier;

[0022] The second optical switch is activated after a first delay following the activation of the first optical switch, so that the optical signal amplified by the EDFA amplifier is output through the second optical switch.

[0023] The first delay time is less than the first duration.

[0024] Thirdly, a signal generation device is provided for use in an optical time-domain reflectometer, comprising:

[0025] The first module is used to turn off the first optical switch and the second optical switch, and to turn on the EDFA amplifier;

[0026] The second module is used to control the first optical switch and the second optical switch to periodically turn on and off to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch is controlled to turn on and off with a delay relative to the first optical switch.

[0027] Fourthly, a communication device is provided, comprising: a memory, a processor, and a program stored in the memory and executable on the processor; the processor is configured to read the program in the memory to implement the steps in the above-described signal generation method.

[0028] Fifthly, a computer-readable storage medium is provided for storing a program that, when executed by a processor, implements the steps in the above-described signal generation method.

[0029] The beneficial effects of the technical solution provided in this application include:

[0030] This application provides an optical time-domain reflectometer, a signal generation method, apparatus, device, and medium, comprising a laser, a first optical switch, an EDFA amplifier, and a second optical switch connected in sequence. The first and second optical switches are connected to an optical switch timing control unit. The optical switch timing control unit controls the periodic opening and closing of the first and second optical switches to generate periodic optical pulse signals. Within one cycle, the second optical switch opens and closes with a delay relative to the first optical switch. This delayed opening and closing of the second optical switch relative to the first optical switch generates the desired optical pulse signal. The required pulse width of the optical pulse, in addition to the periodic output optical pulse signal, is caused by the periodic opening and closing of the second and first optical switches. When the optical signal is output normally in the current cycle, the erbium ions excited by the pump light of the EDFA amplifier amplify the signal light. If the first optical switch cuts off the input light, the metastable erbium ions continue to accumulate to the saturation state. When the signal light input is restored in the next cycle, an energy jump will occur, resulting in an optical surge. This causes the output optical power to increase instantaneously, increasing the peak value of the pulse. This can improve the dynamic range of the optical time domain reflectometer and realize the detection of hollow optical fibers. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of the architecture of an optical temporal reflectometer according to a first embodiment of this application;

[0033] Figure 2 A schematic diagram of the architecture of an optical temporal reflectometer according to a second embodiment of this application;

[0034] Figure 3 A timing diagram of the control signal for generating optical pulses provided in an embodiment of this application.

[0035] In the diagram: 1. Laser; 2. First optical switch; 3. EDFA amplifier; 4. Second optical switch; 5. Optical switch timing control unit; 6. Optical circulator; 7. Detector; 8. Signal analysis unit; 9. First coupler; 10. Second coupler. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] The following should be understood regarding this application:

[0038] Firstly, the main reason for the surge phenomenon is that the dynamic gain of the EDFA changes slowly and cannot quickly adapt to the energy jumps of the input signal. When the optical path is normal, erbium ions excited by the pump light amplify the signal light. If the input light is cut off, because the metastable erbium ions continue to accumulate to the saturation state, an energy jump will occur once the signal light input is restored, resulting in an optical surge.

[0039] In other words, when the input signal energy changes suddenly, the gain adjustment of the EDFA cannot keep up with this change, causing a sudden increase in output optical power, resulting in a spike. This spike in optical power can reach several watts, damaging devices such as photoelectric converters and optical connectors. The surge phenomenon is even more pronounced in periodic pulse signals.

[0040] In order to eliminate or reduce the impact of optical surges, it is generally necessary to install optical surge protection devices. By controlling the pump power of the EDFA, the pump power can be adjusted in time when the input signal energy changes, thereby avoiding the generation of optical surges.

[0041] Secondly, for the testing of ordinary single-mode optical fibers, optical time-domain reflectometry (OTDR) is generally used. It measures the transmission characteristics of the fiber based on the backscattering of the silica fiber core and is widely used in fiber optic construction and maintenance. However, because the backscattering of hollow-core optical fibers is about 30 dB lower than that of traditional single-mode fibers, currently available commercial OTDRs are not suitable. The reason for this inapplicability is that the 30 dB lower backscattering necessitates a higher peak power pulse, which would improve the dynamic range of the optical time-domain reflectometry and enable the measurement and characterization of the transmission loss coefficient of hollow-core optical fibers.

[0042] Therefore, this application utilizes the surge phenomenon of EDFA, which is generally considered to need to be eliminated or suppressed, to improve the peak power of pulsed light. The specific technical solution is described in detail below:

[0043] Firstly, reference Figure 1 and Figure 3An optical time domain reflectometer is provided, which includes: a laser 1, a first optical switch 2, an EDFA amplifier 3, and a second optical switch 4 connected in sequence.

[0044] The first optical switch 2 and the second optical switch 4 are connected to an optical switch timing control unit 5; the optical switch timing control unit 5 is used to control the first optical switch 2 and the second optical switch 4 to periodically open and close, so as to form a periodic optical pulse signal.

[0045] In one cycle, the second optical switch 4 is delayed in opening and delayed in closing relative to the first optical switch 2.

[0046] The above-mentioned control of the second optical switch 4 to turn on and off with a delay relative to the first optical switch 2 can generate the required pulse width of the optical pulse. In addition, the output periodic optical pulse signal is caused by the periodic opening and closing of the second optical switch 4 and the first optical switch 2. When the optical signal of the current cycle is output normally, the erbium ions excited by the pump light of the EDFA amplifier 3 amplify the signal light. If the first optical switch 2 cuts off the input light, since the metastable erbium ions continue to accumulate to the saturation state, the next cycle when the signal light input is restored will produce an energy jump, resulting in an optical surge, which will cause the output optical power to increase instantaneously and increase the peak value of the pulse. This can improve the dynamic range of the optical time domain reflectometer and realize the detection of hollow optical fiber.

[0047] The above utilizes the optical surge phenomenon of the EDFA amplifier 3, which needs to be suppressed in related technologies, to increase the peak value of the optical pulse signal, thereby enabling the optical time domain reflectometer to be used with hollow fiber that has a backscattering of about 30dB compared to traditional single-mode fiber.

[0048] Furthermore, the optical switch timing control unit 5 is also used to adjust the first delay time for the second optical switch 4 to turn on relative to the first optical switch 2 within one cycle, and to adjust the second delay time for the second optical switch 4 to turn off relative to the first optical switch 2; the second delay time is related to the length of time to complete each cycle. This achieves the control of the bandwidth of different optical pulse signals by controlling the first delay time, which can be referred to... Figure 3 The timing diagram of the control signal for the generated optical pulse is shown. After the first optical switch 2 is opened, the second optical switch 4 is opened after a first delay time T2. The high-power optical pulse signal, amplified by the EDFA amplifier 3, is finally output from the second optical switch 4, and the width of the output optical pulse is T3 = T1 - T2. The first optical switch 2 is opened and maintained for a first duration T1.

[0049] Ultimately, by controlling the timing difference between the opening of the second optical switch 4 and the first optical switch 2, precise control of the optical pulse width is achieved. At the same time, the optical surge effect of the EDFA amplifier 3 is used to generate a high-power optical pulse signal.

[0050] In some preferred embodiments, the optical time domain reflectometer further includes a fiber optic link component under test and an optical signal receiving component; the fiber optic link component under test is connected to the optical output end of the second optical switch 4 and is used to connect to the fiber under test; the optical signal receiving component is connected to the fiber optic link component under test and is used to receive and detect the backscattered optical signal returned by the fiber optic link component under test, and to plot the backscattering curve.

[0051] The fiber optic link assembly under test includes an optical circulator 6 connected to the optical output end of the second optical switch 4. The detection end of the optical circulator 6 is connected to a fiber optic link, which is used to send the periodic optical pulse signal output from the second optical switch 4 to the fiber optic link under test. The fiber optic link under test is... Figure 1 Mark A in the diagram. The light output terminal of the second optical switch 4 is located at... Figure 1 The middle is marked as 'a', and the optical circulator 6 detection end is at... Figure 1 The middle part is marked as b.

[0052] The optical signal receiving component includes a detector 7 and a signal analysis unit 8; the signal receiving end of the optical circulator 6 is connected to the detector 7, and the output end of the detector 7 is connected to the signal analysis unit 8; the signal receiving end of the optical circulator 6 is... Figure 1 The label in the text is c.

[0053] Detector 7 outputs an electrical signal based on the received backscattered light signal; the backscattered signal propagates in the opposite direction to the periodic optical pulse signal; signal analysis unit 8 plots the backscattering curve from the electrical signal; the backscattered light signal is generated by the interaction between the periodic optical pulse signal and the fiber under test, i.e., the periodic optical pulse signal interacts with the fiber under test to continuously generate a backscattered light signal; for ordinary single-mode optical fibers with silica core, the backscattering signal is mainly Rayleigh scattering; for hollow-core optical fibers, the backscattering signal mainly originates from the gas in the core. The backscattering curve can be used to obtain information such as the attenuation and length of hollow-core optical fibers, and can also be used for fault diagnosis of optical fiber links.

[0054] The signal analysis unit 8 and detector 7 described above are conventional structures used in optical time domain reflectometers for ordinary single-mode optical fibers. The specific methods of analysis will not be explained or described in detail in this application.

[0055] In some preferred embodiments, reference Figure 2 As shown, the following settings are used to improve the detection sensitivity of detector 7:

[0056] A first coupler 9 is provided between the laser 1 and the first optical switch 2;

[0057] A second coupler 10 is provided between the signal receiving end of the detector 7 and the optical circulator 6; the first coupler 9 and the second coupler 10 are connected to send part of the light from the laser 1 to the input end of the second coupler 10.

[0058] The first coupler 9 sends part of the light from the laser 1 to the input of the second coupler 10, that is, sends the local oscillator light to the input of the second coupler 10; the second coupler 10 couples the returned backscattered light signal to complete coherent reception, thereby improving the detection sensitivity; that is, by comparing the phase and amplitude differences between the backscattered light signal and the local oscillator light, coherent detection technology can achieve accurate measurement and analysis of optical signals.

[0059] Secondly, a signal generation method is provided, which is applied to an optical time-domain reflectometer, including the following steps:

[0060] Step 100: Close the first optical switch 2 and the second optical switch 4, and turn on the EDFA amplifier 3. Step 100 is an initial state in which the first optical switch 2 and the second optical switch 4 are closed, the EDFA amplifier 3 is in operation, the pump laser is turned on, and the erbium ions in the erbium-doped fiber are in an excited state. At this time, the EDFA amplifier 3 outputs a spontaneous emission light signal, and this light signal is blocked by the second optical switch 4. There is no light signal at the light output end of the second optical switch 4.

[0061] Step 200: Control the first optical switch 2 and the second optical switch 4 to periodically turn on and off to form a periodic optical pulse signal; wherein, within one cycle, control the second optical switch 4 to turn on and off with a delay relative to the first optical switch 2. (Reference) Figure 3 Step 200 specifically involves:

[0062] The first optical switch 2 is controlled to open and remain open for a first duration T1, and the optical signal from the laser 1 is input into the EDFA amplifier 3.

[0063] The second optical switch 4 is turned on after a first delay time T2 after the first optical switch 2 is turned on, so that the optical signal amplified by the EDFA amplifier 3 is output through the second optical switch 4; the second optical switch 4 is turned off after a second delay time after the first optical switch 2 is turned off, so as to control the time required to complete the cycle.

[0064] The first delay time T2 is less than the first duration T1.

[0065] The above-mentioned control of the second optical switch 4 to turn on and off with a delay relative to the first optical switch 2 can generate the required pulse width of the optical pulse. In addition, the output periodic optical pulse signal is caused by the periodic opening and closing of the second optical switch 4 and the first optical switch 2. When the optical signal of the current cycle is output normally, the erbium ions excited by the pump light of the EDFA amplifier 3 amplify the signal light. If the first optical switch 2 cuts off the input light, since the metastable erbium ions continue to accumulate to the saturation state, the next cycle when the signal light input is restored will produce an energy jump, resulting in an optical surge, which will cause the output optical power to increase instantaneously and increase the peak value of the pulse. This can improve the dynamic range of the optical time domain reflectometer and realize the detection of hollow optical fiber.

[0066] Thirdly, a signal generation device is provided for use in an optical time-domain reflectometer, comprising:

[0067] The first module is used to turn off the first optical switch 2 and the second optical switch 4, and to turn on the EDFA amplifier 3;

[0068] The second module is used to control the first optical switch 2 and the second optical switch 4 to periodically turn on and off to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch 4 is controlled to turn on and off with a delay relative to the first optical switch 2.

[0069] The apparatus provided in this application embodiment can execute the above method embodiment, and its implementation principle and technical effect are similar, so it will not be described again here.

[0070] It should be noted that the division of units in the embodiments of this application is illustrative and only represents one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units described above can be implemented in hardware or as software functional units.

[0071] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a processor-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0072] This application provides a communication device, including: a memory, a processor, and a program stored in the memory and executable on the processor; the processor is configured to read the program in the memory to implement the steps in the signal generation method described above.

[0073] This application also provides a readable storage medium storing a program. When executed by a processor, this program implements the various processes of the above-described signal generation method embodiments and achieves the same technical effect. To avoid repetition, it will not be described again here. The readable storage medium can be any available medium or data storage device that the processor can access, including but not limited to magnetic storage (e.g., floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (e.g., CDs, DVDs, BDs, HVDs, etc.), and semiconductor storage (e.g., ROMs, EPROMs, EEPROMs, non-volatile memory (NAND flash), solid-state drives (SSDs)).

[0074] This application also provides a computer program product, including computer instructions. When executed by a processor, the computer instructions implement the various processes of the above-described signal generation method embodiments and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0075] It should be noted that, in this document, 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. Unless otherwise specified, 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 that element.

[0076] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0077] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0078] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

Claims

1. An optical time-domain reflectometer, characterized in that, It includes: A laser (1), a first optical switch (2), an EDFA amplifier (3), and a second optical switch (4) are connected in sequence. The first optical switch (2) and the second optical switch (4) are connected to an optical switch timing control unit (5); the optical switch timing control unit (5) is used to control the first optical switch (2) and the second optical switch (4) to periodically open and close, so as to form a periodic optical pulse signal; In one cycle, the second optical switch (4) is delayed in opening and delayed in closing relative to the first optical switch (2); The optical time domain reflectometer also includes a fiber optic link component under test and an optical signal receiving component; the fiber optic link component under test is connected to the optical output end of the second optical switch (4) and is used to connect to the fiber optic link under test; the optical signal receiving component is connected to the fiber optic link component under test and is used to receive and detect the backscattered optical signal returned by the fiber optic link component under test, and to plot the backscattering curve. The fiber optic link assembly under test includes an optical circulator (6) connected to the optical output end of the second optical switch (4). The detection end of the optical circulator (6) is connected to an optical fiber link, which is used to send the periodic optical pulse signal output by the second optical switch (4) to the fiber optic link under test. The optical signal receiving component includes a detector (7) and a signal analysis unit (8); the signal receiving end of the optical circulator (6) is connected to the detector (7), and the output end of the detector (7) is connected to the signal analysis unit (8); the detector (7) is used to output an electrical signal based on the received backscattered optical signal; the signal analysis unit (8) is used to plot the backscattering curve of the electrical signal; the backscattered optical signal is generated by the interaction of a periodic optical pulse signal with the optical fiber under test.

2. The optical time-domain reflectometer as described in claim 1, characterized in that: The optical switch timing control unit (5) is also used to adjust the first delay time of the second optical switch (4) relative to the first optical switch (2) in one cycle.

3. The optical time-domain reflectometer as described in claim 1, characterized in that: A first coupler (9) is provided between the laser (1) and the first optical switch (2); A second coupler (10) is provided between the signal receiving end of the detector (7) and the optical circulator (6); the first coupler (9) and the second coupler (10) are connected to send part of the light from the laser (1) to the input end of the second coupler (10).

4. A signal generation method, characterized in that, Its application in the optical time-domain reflectometer as described in claim 1 includes: Close the first optical switch (2) and the second optical switch (4), and turn on the EDFA amplifier (3); The first optical switch (2) and the second optical switch (4) are controlled to periodically open and close to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch (4) is controlled to open and close with a delay relative to the first optical switch (2).

5. The signal generation method as described in claim 4, characterized in that, Controlling the second optical switch (4) to turn on and off with a delay relative to the first optical switch (2) within one cycle includes the following steps: Control the first optical switch (2) to open and maintain it for a first duration, and input the optical signal of the laser (1) into the EDFA amplifier (3); The second optical switch (4) is turned on after a first delay after the first optical switch (2) is turned on, so that the optical signal amplified by the EDFA amplifier (3) is output through the second optical switch (4); The first delay time is less than the first duration.

6. A signal generation device, characterized in that, Applied to the optical time-domain reflectometer as described in claim 1, comprising: The first module is used to turn off the first optical switch (2) and the second optical switch (4) and turn on the EDFA amplifier (3); The second module is used to control the first optical switch (2) and the second optical switch (4) to periodically turn on and off to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch (4) is controlled to turn on and off with a delay relative to the first optical switch (2).

7. A communication device, comprising: A memory, a processor, and a program stored in the memory and executable on the processor; characterized in that the processor is configured to read the program in the memory to implement the steps of the signal generation method as described in any one of claims 4 to 5.

8. A computer-readable storage medium for storing a program, characterized in that, When the program is executed by the processor, it implements the steps in the signal generation method as described in any one of claims 4 to 5.

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