Optical time domain reflectometer, signal generation method, device, equipment and medium

Abstract

The invention relates to an optical time domain reflectometer, a signal generation method and device, equipment and a medium. The optical time domain reflectometer comprises a laser, a first optical switch, an EDFA amplifier and a second optical switch which are connected in sequence. The optical switch time sequence control unit controls the first optical switch and the second optical switch to be periodically turned on and turned off so as to form a periodic optical pulse signal; wherein the second optical switch is turned on and turned off in a delayed manner relative to the first optical switch in a period, and the pulse width of the required optical pulse can be generated by controlling the delayed turn-on and the delayed turn-off; when a current period optical signal is normally output, the signal light is amplified by erbium ions excited by the pump light of the EDFA amplifier; if input light is cut off, erbium ions in a metastable state are still continuously gathered to a saturation state, signal light input is recovered in the next period, energy jump is generated, light surge is caused, output light power is instantly increased, and a pulse peak value is increased, so that the dynamic range of the optical time domain reflectometer is improved, and detection of the hollow-core optical fiber is realized.

Description

Technical Field

[0001] The present application relates to the field of optical fiber detection technology, and in particular to a signal generation method and an optical time domain reflectometer thereof. Background Art

[0002] In recent years, with the rapid development of antiresonant hollow-core fiber technology, it has attracted extensive attention from the optical fiber communication industry and academia due to its advantages of low latency, low nonlinearity, and low loss, and has been the subject of extensive research. Currently, commercial optical fiber transmission systems are mainly based on traditional single-mode optical fibers, and the transmission speed of internal optical signals is about 2×10 8 m / s, the time delay is greater than that of air. At the same time, due to the high temperature sensitivity of glass, its transmission delay varies greatly with temperature; its core is solid silica (refractive index is about 1.44), and the backscattering coefficient is generally around -72dB / m. The core of hollow-core fiber is air (refractive index is about 1.003), and the transmission speed of the internal optical signal is about 3×10 8 m / s, the propagation speed can be increased by 46% and the delay can be reduced by 30% compared with the traditional single-mode fiber, and the temperature stability of the delay can be improved by about 20 times. At the same time, the backscattering is about 30dB lower than that of the traditional single-mode fiber, and it also has ultra-low nonlinearity and ultra-wide wavelength range. These advantages mean that when using hollow-core fiber, higher fiber input power can be used, the fiber transmission span can be increased, the number of optical amplification nodes in long-distance transmission can be reduced, the structure of the optical fiber link can be greatly simplified, and the network operation power consumption and construction cost can be reduced. Therefore, the future transmission system based on hollow-core fiber will have many advantages.

[0003] For the detection of ordinary single-mode optical fiber, Optical Time-Domain Reflectometry (OTDR) is generally used for detection. It measures the transmission characteristics of optical fiber based on the backscattering of the silica core and is widely used in the construction and maintenance of optical fiber. However, since the backscattering of hollow-core optical fiber is about 30dB lower than that of traditional single-mode optical fiber, currently ordinary commercial OTDR is not applicable. Summary of the invention

[0004] The embodiments of the present application provide 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 the current optical time domain reflectometer cannot be used for hollow core optical fibers whose backscattering is 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 be periodically turned on and off to form a periodic optical pulse signal;

[0007] Wherein, in one cycle, the second optical switch is turned on and off with a time delay relative to the first optical switch.

[0008] In some embodiments, the optical switch timing control unit is further used to adjust a first delay time of delayed opening of the second optical switch relative to the first optical switch in one cycle.

[0009] In some embodiments, the optical time domain reflectometer further includes an optical fiber link component to be tested and an optical signal receiving component;

[0010] The optical fiber link assembly to be tested is connected to the optical output end of the second optical switch and is used to be connected to the optical fiber to be tested;

[0011] The optical signal receiving component is connected to the optical fiber link component to be tested, and is used to receive and detect the backscattered optical signal returned by the optical fiber link component to be tested, and to draw a backscattering curve.

[0012] In some embodiments, the optical fiber link component to be tested 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 an optical fiber link, and the optical fiber link is used to send the periodic optical pulse signal output by the second optical switch to the optical fiber to be tested;

[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 according to the received backscattered light signal; the signal analysis unit is used to draw a backscattering curve based on the electrical signal; the backscattered light signal is generated by the interaction between the periodic light pulse signal and the optical fiber to be tested.

[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 detector and the signal receiving end of 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] In a second aspect, a signal generation method is provided, which is applied to an optical time domain reflectometer, comprising:

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

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

[0020] In some embodiments, controlling the second optical switch to be turned on and off with a delay relative to the first optical switch in a cycle comprises the following steps:

[0021] Controlling the first optical switch to open and maintain a first duration, and inputting the optical signal of the laser into the EDFA amplifier;

[0022] Controlling the second optical switch to be turned on after a first delay time after the first optical switch is turned on, so that the optical signal amplified by the EDFA amplifier is output through the second optical switch;

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

[0024] In a third aspect, a signal generating device is provided, which is applied to an optical time domain reflectometer, comprising:

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

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

[0027] In a fourth aspect, 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-mentioned signal generation method.

[0028] In a fifth aspect, a computer-readable storage medium is provided for storing a program, wherein the program, when executed by a processor, implements the steps in the above-mentioned signal generation method.

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

[0030] The embodiments of the present application provide an optical time domain reflectometer, a signal generation method, an apparatus, a device, and a medium. The laser, the first optical switch, the EDFA amplifier, and the second optical switch are connected in sequence; 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 be periodically turned on and off to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch is delayed to be turned on and off relative to the first optical switch, and the above control of the second optical switch to be delayed to be turned on and off relative to the first optical switch can generate the above The pulse width of the optical pulse is required. In addition, the periodic optical pulse signal output is caused by the periodic opening and closing of the second optical switch and the first optical switch. When the optical signal of the current cycle is output normally, the erbium ions excited by the pump light of the EDFA amplifier complete the amplification of the signal light; if the first optical switch cuts off the input light, the metastable erbium ions continue to gather to the saturation state, and the signal light input is restored in the next cycle, which will produce an energy jump, resulting in an optical surge, so that the output optical power increases instantly, and the pulse peak value is increased, thereby improving the dynamic range of the optical time domain reflectometer and realizing the detection of hollow-core optical fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 A schematic diagram of the architecture of an optical time domain reflectometer of a first embodiment provided in the embodiments of the present application;

[0033] Figure 2 A schematic diagram of the architecture of an optical time domain reflectometer of a second embodiment provided in the embodiments of the present application;

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

[0035] In the figure: 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 DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

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

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

[0039] That is to say, when the input signal energy changes suddenly, the gain adjustment of EDFA cannot keep up with the change, resulting in an instantaneous increase in the output optical power and a spike. The optical power of this spike may reach several watts, causing damage to devices such as optoelectronic converters and optical connectors. The surge phenomenon is more obvious in periodic pulse signals.

[0040] Generally, in order to eliminate or reduce the impact of optical surges, it is necessary to install an optical surge protection device. By controlling the EDFA pump power, 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 detection of 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 core and is widely used in the construction and maintenance of optical fibers. However, since the backscattering of hollow-core optical fibers is about 30 dB lower than that of traditional single-mode optical fibers, currently common commercial OTDRs are not applicable. The reason for this is that the backscattering is about 30 dB lower than that of traditional single-mode optical fibers, requiring a higher peak power of pulsed light, thereby improving the dynamic range of the optical time-domain reflectometer and achieving the measurement and characterization of the transmission loss coefficient of hollow-core optical fibers.

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

[0043] First, refer to Figure 1 and Figure 3, an optical time domain reflectometer is provided, which comprises: 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 turn on and off to form a periodic optical pulse signal;

[0045] In one cycle, the second optical switch 4 is turned on and off with a delay relative to the first optical switch 2 .

[0046] The above control of the second optical switch 4 to delay opening and closing relative to the first optical switch 2 can generate the required pulse width of the optical pulse. In addition, the periodic optical pulse signal output 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 normally output, the erbium ions excited by the pump light of the EDFA amplifier 3 complete the amplification of the signal light; if the first optical switch 2 cuts off the input light, since the metastable erbium ions continue to gather to the saturation state, the signal light input is restored in the next cycle, which will generate energy jumps, resulting in optical surges, so that the output optical power increases instantly, and the pulse peak value is increased, thereby improving the dynamic range of the optical time domain reflectometer and realizing the detection of hollow core optical fibers.

[0047] The above utilizes the optical surge phenomenon of the EDFA amplifier 3 that needs to be suppressed in the related art to increase the peak value of the optical pulse signal, so that the optical time domain reflectometer is suitable for hollow-core optical fiber whose backscattering is about 30 dB lower than that of traditional single-mode optical fiber.

[0048] Furthermore, 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 a cycle, and adjust the second delay time of the second optical switch 4 relative to the first optical switch 2 in a cycle; the second delay time is related to the time length to complete each cycle. The above realizes that the bandwidth of different optical pulse signals can be controlled by controlling the first delay time, which can be referred to Figure 3 As shown in the timing diagram of the control signal generated by the optical pulse, after the first optical switch 2 is turned on, the second optical switch 4 is turned on after the first delay time T2, and the high-power optical pulse signal amplified by the EDFA amplifier 3 is finally output from the second optical switch 4, and the output optical pulse width is T3 = T1-T2. The first optical switch 2 is turned on and maintained for the first duration T1.

[0049] Ultimately, the optical pulse width is precisely controlled by controlling the timing difference between the opening of the second optical switch 4 and the opening of the first optical switch 2, and a high-power optical pulse signal is generated by utilizing the optical surge effect of the EDFA amplifier 3.

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

[0051] The optical fiber link component to be tested includes an optical circulator 6 connected to the optical output end of the second optical switch 4, and 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 optical fiber to be tested; the optical fiber to be tested is Figure 1 The light output terminal of the second optical switch 4 is Figure 1 The detection end of the optical circulator 6 is marked as a. Figure 1 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 ... Figure 1 The mark in is c.

[0053] The detector 7 is used to output an electrical signal according to the received backscattered light signal; the backscattered signal propagates in the opposite direction of the periodic light pulse signal; the signal analysis unit 8 is used to draw a backscattering curve for the electrical signal; the backscattered light signal is generated by the interaction between the periodic light pulse signal and the optical fiber to be tested, that is, the periodic light pulse signal interacts with the optical fiber to be tested and continuously generates a backscattered light signal; for ordinary single-mode optical fibers with silica as the core, the backscattered signal is mainly Rayleigh scattering; for hollow-core optical fibers, the backscattered signal mainly comes from the gas in the core. The backscattering curve can be used to obtain information such as the attenuation and length of the hollow-core optical fiber, and can also be used for fault diagnosis of optical fiber links.

[0054] The above signal analysis unit 8 and detector 7 are conventional structures used in an optical time domain reflectometer using a common single-mode optical fiber, and the specific analysis method thereof will not be explained and illustrated in detail in this application.

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

[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 detector 7 and the signal receiving end of the optical circulator 6 ; the first coupler 9 and the second coupler 10 are connected to send part of the light of 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 end of the second coupler 10, that is, sends the local oscillator light to the input end of the second coupler 10; the second coupler 10 couples the returned backscattered light signal to complete coherent reception to improve the detection sensitivity; that is, by comparing the phase and amplitude differences between the backscattered light signal and the local oscillator light, the coherent detection technology can realize the accurate measurement and analysis of the optical signal.

[0059] In a second aspect, a signal generation method is provided, which is applied to an optical time domain reflectometer, comprising 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 in a closed state, the EDFA amplifier 3 is in a working state, 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 spontaneously radiated optical signal, and the optical signal is blocked by the second optical switch 4, and there is no optical signal at the optical output end of the second optical switch 4;

[0061] Step 200: Control the first optical switch 2 and the second optical switch 4 to be periodically turned on and off to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch 4 is controlled to be turned on and off with a delay relative to the first optical switch 2. Figure 3 , step 200 is specifically as follows:

[0062] Controlling the first optical switch 2 to open and maintain a first duration T1, and inputting the optical signal of the laser 1 into the EDFA amplifier 3;

[0063] The second optical switch 4 is controlled to be turned on after the 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 controlled to be turned off after the 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 shorter than the first duration T1.

[0065] The above control of the second optical switch 4 to delay opening and closing relative to the first optical switch 2 can generate the required pulse width of the optical pulse. In addition, the periodic optical pulse signal output 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 normally output, the erbium ions excited by the pump light of the EDFA amplifier 3 complete the amplification of the signal light; if the first optical switch 2 cuts off the input light, since the metastable erbium ions continue to gather to the saturation state, the signal light input is restored in the next cycle, which will generate energy jumps, resulting in optical surges, so that the output optical power increases instantly, and the pulse peak value is increased, thereby improving the dynamic range of the optical time domain reflectometer and realizing the detection of hollow core optical fibers.

[0066] In a third aspect, a signal generating device is provided, which is applied to an optical time domain reflectometer, comprising:

[0067] A first module, which is used to turn off the first optical switch 2 and the second optical switch 4, and 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 be periodically turned on and off to form a periodic optical pulse signal; wherein the second optical switch 4 is controlled to be delayed in opening and closing relative to the first optical switch 2 in one cycle.

[0069] The device provided in the embodiment of the present application can execute the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0070] It should be noted that the division of units in the embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, each functional unit in each embodiment of the present application may be integrated into a processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0071] If the integrated unit is implemented in the form of 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 the present application is essentially 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, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) or a processor (processor) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0072] An embodiment of the present 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 used to read the program in the memory to implement the steps in the signal generation method as described above.

[0073] The embodiment of the present application also provides a readable storage medium, on which a program is stored, and when the program is executed by the processor, each process of the above-mentioned signal generation method embodiment is implemented, and the same technical effect can be achieved. To avoid repetition, it is not repeated here. Among them, the readable storage medium can be any available medium or data storage device that can be accessed by the processor, including but not limited to magnetic storage (such as floppy disk, hard disk, magnetic tape, magneto-optical disk (MO), etc.), optical storage (such as CD, DVD, BD, HVD, etc.), and semiconductor storage (such as ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid-state drive (SSD)), etc.

[0074] The embodiment of the present application also provides a computer program product, including computer instructions. When the computer instructions are executed by a processor, the various processes of the above-mentioned signal generation method embodiment are implemented and the same technical effect can be achieved. To avoid repetition, they are not repeated here.

[0075] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0076] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, disk, CD), including a number of instructions for a terminal (which can be a mobile phone, computer, server, air conditioner, or network equipment, etc.) to execute the methods described in each embodiment of the present application.

[0077] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

[0078] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present 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) 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 turn on and off, so as to form a periodic optical pulse signal; Wherein, in one cycle, the second optical switch (4) is turned on and off with a time delay relative to the first optical switch (2).

2. The optical time domain reflectometer according to claim 1, wherein: The optical switch timing control unit (5) is also used to adjust a first delay time for delayed opening of the second optical switch (4) relative to the first optical switch (2) in one cycle.

3. The optical time domain reflectometer according to claim 1 or 2, characterized in that: The optical time domain reflectometer also includes an optical fiber link component to be tested and an optical signal receiving component; The optical fiber link component to be tested is connected to the optical output end of the second optical switch (4) and is used to be connected to the optical fiber to be tested; The optical signal receiving component is connected to the optical fiber link component to be tested, and is used to receive and detect the backscattered optical signal returned by the optical fiber link component to be tested, and to draw a backscattering curve.

4. The optical time domain reflectometer according to claim 3, wherein: The optical fiber link component to be tested comprises 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, and the optical fiber link is used to send the periodic optical pulse signal output by the second optical switch (4) to the optical fiber to be tested; The optical signal receiving component comprises 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 according to the received backscattered light signal; the signal analysis unit (8) is used to draw a backscattering curve based on the electrical signal; the backscattered light signal is generated by the interaction between a periodic light pulse signal and the optical fiber to be tested.

5. The optical time domain reflectometer according to claim 4, 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 detector (7) and the signal receiving end of the optical circulator (6); the first coupler (9) and the second coupler (10) are connected to send part of the light of the laser (1) to the input end of the second coupler (10).

6. A signal generation method, characterized in that: Its applications in optical time domain reflectometry include: Turning off the first optical switch (2) and the second optical switch (4), and turning on the EDFA amplifier (3); The first optical switch (2) and the second optical switch (4) are controlled to be periodically turned on and off to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch (4) is controlled to be delayed in opening and delayed in closing relative to the first optical switch (2).

7. The signal generating method according to claim 6, characterized in that: Controlling the second optical switch (4) to delay opening and delay closing relative to the first optical switch (2) in one cycle comprises the following steps: Controlling the first optical switch (2) to open and maintain a first duration, and inputting the optical signal of the laser (1) into the EDFA amplifier (3); Controlling the second optical switch (4) to be turned on after a first delay time 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 shorter than the first duration time.

8. A signal generating device, characterized in that: Applications in optical time domain reflectometry, including: A first module, which is used to close the first optical switch (2) and the second optical switch (4), and to open the EDFA amplifier (3); The second module is used to control the first optical switch (2) and the second optical switch (4) to be periodically turned on and off so as to form a periodic optical pulse signal; wherein, in one cycle, the second optical switch (4) is controlled to be turned on and off with a delay relative to the first optical switch (2).

9. A communication device, comprising: A memory, a processor, and a program stored in the memory and executable on the processor; wherein the processor is used to read the program in the memory to implement the steps in the signal generation method as described in any one of claims 6 to 7.

10. A computer-readable storage medium for storing a program, characterized in that: When the program is executed by a processor, the steps in the signal generating method according to any one of claims 6 to 7 are implemented.

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