A signal transmission method, transmission device and optical network

Abstract

Provided are a signal transmission method, a transmission device, and an optical network, which are related to the field of optical transmission and can respectively implement pilot modulation on optical signals of different wavelengths. Meanwhile, the intensity of the optical signals can be obtained based on the pilot-modulated optical signals, and the optical channel performance of a channel transmitting the optical signals can be determined, so as to monitor the optical channel performance of multiple channels. The signal transmission method comprises: obtaining a first optical signal received by a first branch port in multiple branch ports and obtaining a second optical signal received by a second branch port in the multiple branch ports; wherein the wavelengths of the first optical signal and the second optical signal are different; pilot-modulating the first optical signal in the time domain to obtain a first modulated signal; pilot-modulating the second optical signal in the time domain to obtain a second modulated signal; and transmitting the first modulated signal and the second modulated signal to an optical fiber through a common port. Embodiments of the present application are applied to the field of optical transmission.

Description

Technical Field

[0001] This application relates to the field of optical transmission, and more particularly to a signal transmission method, transmission device, and optical network. Background Technology

[0002] Currently, the demand for business data transmission is increasing, and the architecture of optical networks (such as connection methods and the number of links) is becoming more complex. For example, the connection methods and / or the number of links in optical networks are becoming more flexible. In order to meet the transmission requirements of business data, appropriate monitoring methods need to be adopted for the business data transmission process in optical networks to ensure the stable and efficient operation of optical networks and guarantee the normal transmission of business data.

[0003] Among them, dense wavelength division multiplexing (DWDM) systems can meet the transmission requirements of service data and have advantages such as low cost and ease of operation and maintenance, thus they are widely used in production and daily life. Specifically, in order to ensure the stable operation of DWDM systems and reduce interruptions caused by network failures, it is necessary to simultaneously monitor the optical channel performance of each wavelength channel (also known as an optical channel, or simply a channel) in the DWDM system.

[0004] However, there is currently a lack of technical solutions that can effectively monitor the performance of optical channels across multiple wavelength channels. Summary of the Invention

[0005] Embodiments of this application provide a signal transmission method, a transmission device, and an optical network. The signal transmission method can perform pilot modulation on optical signals of different wavelengths. Simultaneously, it can obtain the intensity of the optical signal based on the pilot-modulated optical signal, determine the optical channel performance of the channel transmitting the optical signal, and thereby monitor the optical channel performance of multiple channels.

[0006] A first aspect provides a signal transmission method. This signal transmission method is applied to a first transmission device in an optical network. The first transmission device includes a WSS module, which includes multiple branch ports and a common port. The branch ports are used to connect to an optical transmitter, and the common port is used to connect to an optical fiber. The signal transmission method includes: acquiring a first optical signal received by a first branch port among the multiple branch ports, and acquiring a second optical signal received by a second branch port among the multiple branch ports; wherein the first optical signal and the second optical signal have different wavelengths; performing pilot modulation on the first optical signal in the time domain to acquire a first modulated signal; performing pilot modulation on the second optical signal in the time domain to acquire a second modulated signal; and transmitting the first modulated signal and the second modulated signal to the optical fiber through the common port.

[0007] Therefore, the above scheme can acquire multiple (at least two) optical signals of different wavelengths received from different branch ports, and perform pilot modulation on each of the multiple optical signals of different wavelengths to acquire multiple modulated signals. Further, the acquired multiple modulated signals are output to the optical fiber through a common port. Specifically, it can acquire a first optical signal received from the first branch port and a second optical signal received from the second branch port. The first and second optical signals have different wavelengths. Then, by performing pilot modulation on the first optical signal, a first modulated signal can be acquired; by performing pilot modulation on the second optical signal, a second modulated signal can be acquired. Further, the acquired first and second modulated signals are transmitted to the optical fiber through a common port. Generally, in optical networks such as wavelength division multiplexing (WDM) systems, when optical signals of different wavelengths are transmitted through the same optical fiber, the different wavelengths will be transmitted through different channels in the optical fiber. Taking a DWDM system as an example, the aforementioned first and second modulated signals will be transmitted through different channels in the optical fiber when they are transmitted along the optical fiber. Thus, by determining the transmission quality of the first and second modulated signals after transmission through optical fiber, the optical channel performance of the channels transmitting the first and second modulated signals can be determined separately. Therefore, the above scheme can perform pilot modulation on optical signals of multiple wavelengths using the same transmission device, thereby facilitating the determination of the optical channel performance of multiple channels transmitting multiple modulated signals. Furthermore, this scheme eliminates the need to deploy multiple additional devices or modules in the optical network for pilot modulation, thereby reducing insertion loss and ensuring the transmission quality of the optical network.

[0008] The above scheme can be implemented by a WSS module within the transmission device. Specifically, the WSS module receives multiple (at least two) optical signals of different wavelengths from different branch ports and performs pilot modulation on each of these signals to obtain multiple modulated signals. Further, the WSS module outputs the obtained multiple modulated signals to the optical fiber through a common port. Specifically, the WSS module can acquire a first optical signal received from a first branch port and a second optical signal received from a second branch port. The first and second optical signals have different wavelengths. Then, the WSS module obtains a first modulated signal by performing pilot modulation on the first optical signal; the WSS module obtains a second modulated signal by performing pilot modulation on the second optical signal. Further, the WSS module transmits the first and second modulated signals to the optical fiber through a common port.

[0009] Typically, optical signals within a certain wavelength range and having a certain center wavelength are transmitted within the same channel. That is, the first optical signal is an optical signal within a unit wavelength range and having a certain center wavelength. The second optical signal is an optical signal within a unit wavelength range and having a certain center wavelength.

[0010] Optionally, optical channel performance characterizes transmission parameters such as transmission speed, transmission loss, and transmission bandwidth.

[0011] In one possible implementation, the above signal transmission method further includes: acquiring a third optical signal received by a third branch port among multiple branch ports, wherein the wavelengths of the first optical signal, the second optical signal and the third optical signal are different from each other; performing pilot modulation on the third optical signal in the time domain to acquire a third modulation signal; and transmitting the third modulation signal to an optical fiber through a common port.

[0012] The above scheme allows the acquisition of optical signals received at branch ports, which are then pilot-modulated to obtain modulated signals. The modulated signals are then output to the optical fiber via a common port. Specifically, the transmission device acquires a third optical signal received at the third branch port. The first, second, and third optical signals have different wavelengths. The transmission device then acquires a third modulated signal by pilot-modulating the third optical signal. The modulated third signal is then transmitted to the optical fiber via the common port. Furthermore, based on the other schemes described above, the transmission device can also pilot-modulate the acquired first and second optical signals and transmit these signals to the optical fiber. Therefore, this scheme allows pilot-modulation of multiple wavelengths (at least three or more) of optical signals using the same transmission device, facilitating the determination of the optical channel performance for multiple channels transmitting multiple modulated signals. This scheme offers higher efficiency in pilot-modulating optical signals.

[0013] In one possible implementation, pilot modulation of the first optical signal in the time domain includes: intensity modulation of the first optical signal in the time domain; pilot modulation of the second optical signal in the time domain includes: intensity modulation of the second optical signal in the time domain.

[0014] In the above scheme, pilot modulation of the first optical signal is achieved by intensity modulation of the first optical signal in the time domain. Similarly, pilot modulation of the second optical signal is achieved by intensity modulation of the second optical signal in the time domain. Typically, intensity modulation refers to changing the power of the optical signal through a pilot signal. Based on this, determining the power of the modulated signal after transmission through the corresponding channel allows for the determination of the transmission quality of the modulated signal after transmission through the corresponding channel, thereby determining the optical channel performance of the channels transmitting the first and second modulated signals respectively.

[0015] In one possible implementation, pilot modulation of the first optical signal in the time domain includes: intensity modulation of the first optical signal in the time domain using a first pilot signal; pilot modulation of the second optical signal in the time domain includes: intensity modulation of the second optical signal in the time domain using a second pilot signal; wherein the first pilot signal and the second pilot signal have different frequencies.

[0016] In the above scheme, different wavelengths of optical signals can be intensity modulated in the time domain using pilot signals of different frequencies. Specifically, the transmission device can intensity modulate a first optical signal using a first pilot signal in the time domain. Similarly, the transmission device can intensity modulate a second optical signal using a second pilot signal in the time domain. The first and second pilot signals have different frequencies. Based on this, modulating optical signals of different wavelengths using different frequencies establishes a correlation between the wavelength, the channel transmitting the optical signal of that wavelength, and the frequency of the modulation signal. This facilitates the determination of the channel transmitting an optical signal of a specific wavelength, or the determination of the optical channel performance by detecting the modulation signal transmitted through the channel. For example, the channel corresponding to the modulation signal can be determined by the frequency of the modulation signal transmitted through the channel. Furthermore, the optical channel performance can be determined by determining the transmission quality after the modulation signal is transmitted.

[0017] In one possible implementation, pilot modulation of the first optical signal in the time domain to obtain a first modulation signal includes: in the time domain, pilot modulation of a first portion of the optical signal in the first optical signal using a third pilot signal to obtain a first portion modulation signal of the first optical signal; in the time domain, pilot modulation of a second portion of the optical signal in the first optical signal using a fourth pilot signal to obtain a second portion modulation signal of the first optical signal; and obtaining the first modulation signal based on the first and second portion modulation signals; wherein the phase of the third pilot signal differs from the phase of the fourth pilot signal by 180 degrees, and the third and fourth pilot signals have the same frequency.

[0018] In the above scheme, intensity modulation of the same wavelength optical signal can be achieved by using different pilot signals with opposite phases and the same frequency in the time domain. Specifically, in the time domain, the transmission device can perform pilot modulation on the second part of the first optical signal using a third pilot signal. Similarly, in the time domain, the transmission device can perform pilot modulation on the first part of the first optical signal using a fourth pilot signal. The phases of the third and fourth pilot signals differ by 180 degrees (i.e., they are opposite in phase), and their frequencies are the same. Generally, due to the extremely high SRS crosstalk generated by stimulated Raman scattering (SRS) on low-frequency signals, pilot modulation of optical signals using low-frequency pilot signals has a significant impact on the transmission quality of the modulated optical signal along the channel. This makes it impossible to accurately determine the power of optical signals at different wavelengths, thus affecting the detection of the optical channel performance. Based on this, SRS crosstalk can be suppressed by modulating a pair of pilot signals with opposite phases and the same frequency within the same channel. Thus, the above scheme, by using different pilot signals with opposite phases and the same frequency, can modulate different parts of the optical signal transmitted within the same channel, thereby suppressing SRS crosstalk and ensuring the accuracy of optical channel performance detection.

[0019] Based on the above scheme, in order to further improve the effect of the above scheme in suppressing SRS, multiple pairs of anti-phase pilot pairs with the same frequency (i.e., multiple sets of pilot signals with opposite phases and the same frequency) can also be modulated in the same channel to suppress SRS crosstalk. Among them, when different parts of the optical signal in the same channel (e.g., including the first part of the optical signal to the third part of the optical signal) are pilot modulated by multiple pairs of anti-phase pilot pairs, the pilot signals modulated by two adjacent parts of the optical signal (i.e., the first part of the optical signal and the third part of the optical signal) have opposite phases.

[0020] For example, modulation of the same channel can be achieved using two pairs of anti-phase pilots (including two sets of pilot signals with opposite phases and the same frequency, such as the first and second anti-phase pilot pairs). That is, by using two sets of pilot signals with frequencies and phases of -f1 and +f1 (i.e., the first anti-phase pilot pair) and +f1 and -f1 (i.e., the second anti-phase pilot pair), pilot modulation can be performed on the four parts of the optical signal within the same channel, respectively. Alternatively, by using two sets of pilot signals with frequencies and phases of +f1 and -f1 and -f1 and +f1, pilot modulation can be performed on the four parts of the optical signal within the same channel, respectively. In this case, the pilot signals modulated by non-adjacent optical signals have opposite phases.

[0021] Based on the above scheme, for different channels, it is necessary to use anti-phase pilot pairs with different frequencies to modulate each channel separately.

[0022] For example, modulation of two channels (e.g., the first and second channels) can be achieved using four pairs of anti-phase pilots (including four sets of pilot signals with opposite phases and the same frequency, such as the first to fourth sets of anti-phase pilot pairs). Specifically, pilot modulation can be performed on four parts of the optical signal within the same channel using two sets of pilot signals with frequencies and phases of -f1 and +f1 (i.e., the first set of anti-phase pilot pairs) and +f1 and -f1 (i.e., the second set of anti-phase pilot pairs). Alternatively, pilot modulation can be performed on four parts of the optical signal within the first channel using two sets of pilot signals with frequencies and phases of +f1 and -f1 and -f1 and +f1, respectively. The pilot signals modulated by non-adjacent parts of the optical signal within the same channel have opposite phases. Similarly, pilot modulation can be performed on four parts of the optical signal within the same channel using two sets of pilot signals with frequencies and phases of -f2 and +f2 (i.e., the third set of anti-phase pilot pairs) and +f2 and -f2 (i.e., the fourth set of anti-phase pilot pairs). Alternatively, pilot modulation can be applied to the four optical signals within the second channel using two sets of pilot signals with frequencies and phases of +f2, -f2, and -f2, respectively. The pilot signals modulated by non-adjacent optical signals within the same channel have opposite phases.

[0023] In one possible implementation, pilot modulation of the first optical signal in the time domain to obtain a first modulation signal includes: in the time domain, pilot modulation of a first portion of the first optical signal using a fifth pilot signal to obtain a third portion modulation signal of the first optical signal; in the time domain, pilot modulation of a second portion of the first optical signal using a sixth pilot signal to obtain a fourth portion modulation signal of the first optical signal; and obtaining the first modulation signal based on the third and fourth portion modulation signals; wherein the fifth and sixth pilot signals have different frequencies.

[0024] In the above scheme, frequency modulation of the same wavelength optical signal within the same channel can be achieved separately in the time domain using pilot signals of different frequencies. Specifically, in the time domain, the transmission device can perform pilot modulation on the first part of the first optical signal using the fifth pilot signal to obtain the third part of the modulated signal of the first optical signal. Similarly, in the time domain, the transmission device can perform pilot modulation on the second part of the first optical signal using the sixth pilot signal to obtain the fourth part of the modulated signal of the first optical signal. The fifth and sixth pilot signals have different frequencies. Based on this, the power of the different modulated signals (i.e., the third and fourth modulated signals) after transmission through the corresponding channel can be determined, and the transmission quality of the different modulated signals after transmission through the corresponding channel can be determined, thereby determining the optical channel performance of different parts of the channel. Therefore, the above scheme, by using different pilot signals of different frequencies, can modulate different parts of the same optical signal within the same channel, thereby determining the optical channel performance of different parts of the channel, and thus improving the detection accuracy of the channel's optical channel performance.

[0025] In one possible implementation, pilot modulation of the first optical signal in the time domain to obtain a first modulation signal includes: in the time domain, pilot modulation of a first portion of the first optical signal using a seventh pilot signal to obtain a seventh portion modulation signal of the first optical signal; in the time domain, pilot modulation of a second portion of the first optical signal using an eighth pilot signal to obtain an eighth portion modulation signal of the first optical signal; and in the time domain, pilot modulation of a third portion of the first optical signal using a ninth pilot signal to obtain a ninth portion modulation signal of the first optical signal. The seventh, eighth, and ninth modulation signals are used to obtain the first modulation signal; wherein, the wavelength of the first optical signal is shorter than the wavelength of the second optical signal, and the wavelength of the second optical signal is shorter than the wavelength of the third optical signal; or, the wavelength of the second optical signal is shorter than the wavelength of the third optical signal; the wavelength of the first optical signal is longer than the wavelength of the third optical signal; the seventh pilot signal and the eighth pilot signal are 180 degrees out of phase, and the seventh pilot signal and the eighth pilot signal have the same frequency; the seventh pilot signal and the ninth pilot signal have different frequencies.

[0026] In the above scheme, at least three parts of the optical signal of the same wavelength within the same channel can be pilot-modulated in the time domain. Specifically, the wavelengths of the first, second, and third parts of the optical signal are distributed in ascending order, or the wavelengths of the second, third, and first parts of the optical signal are distributed in ascending order. In the time domain, the transmission device can sequentially perform pilot modulation on the first and second parts of the first optical signal using a seventh pilot signal and an eighth pilot signal, respectively, and acquire the seventh and eighth modulated signals of the first optical signal. The seventh and eighth pilot signals are 180 degrees out of phase (i.e., out of phase), and have the same frequency, meaning they form an anti-phase pilot pair. Based on the above scheme, pilot modulation of different parts of the optical signal within the same channel using anti-phase pilots can cancel the SRS effect. Therefore, the SRS effect can be canceled based on the seventh and eighth modulated signals. Simultaneously, this scheme also uses a ninth pilot signal with a different frequency to pilot-modulate the ninth portion of the optical signal within the same channel. Thus, the ninth portion of the modulated signal does not cancel out the SRS effect. Furthermore, by receiving and detecting the intensity difference (e.g., power difference) between the inverted modulation signal (i.e., the seventh and eighth portion modulation signals) and the non-inverted modulation signal (i.e., the ninth portion modulation signal), the numerical value of SRS crosstalk caused by the SRS effect can be determined.

[0027] In some examples, based on the above scheme, pilot modulation of the optical signal within the same channel can be performed separately using multiple pilot signals comprising more sets of anti-phase pilot pairs. For example, pilot modulation of five parts of the optical signal within the same channel can be performed separately using five pilot signals with frequencies and phases of -f1, -f1, +f1 (i.e., the first set of anti-phase pilot pairs) and +f1, -f1 (i.e., the second set of anti-phase pilot pairs). As another example, pilot modulation of five parts of the optical signal within the same channel can be performed separately using five pilot signals with frequencies and phases of +f1, -f1, +f1 (i.e., the first set of anti-phase pilot pairs) and +f1, -f1 (i.e., the second set of anti-phase pilot pairs).

[0028] Since optical signals within a certain wavelength range and having a certain center wavelength are typically transmitted within the same channel, the first, second, and third parts of the optical signal are respectively optical signals within a unit wavelength range and having a certain center wavelength in the first optical signal. The first, second, and third parts of the optical signal may have the same or different wavelength ranges.

[0029] In one possible implementation, pilot modulation of the first optical signal in the time domain to obtain a first modulated signal includes: in the time domain, sequentially pilot-modulating a first portion of the optical signal to an eighth portion of the first optical signal using a tenth pilot signal, an eleventh pilot signal, a twelfth pilot signal, a thirteenth pilot signal, a fourteenth pilot signal, a fifteenth pilot signal, a sixteenth pilot signal, and a seventeenth pilot signal to obtain the first modulated signal; wherein the wavelengths of the first portion of the optical signal to the eighth portion of the optical signal are distributed in ascending order; the tenth pilot signal... The 11th, 12th, 15th, and 17th pilot signals have a first frequency, while the 11th, 13th, 14th, and 16th pilot signals have a second frequency; the first frequency and the second frequency are different; the 10th, 11th, 16th, and 17th pilot signals have the same phase, and the 12th, 13th, 14th, and 15th pilot signals have the same phase; the 11th pilot signal and the 12th pilot signal have a phase difference of 180 degrees.

[0030] Specifically, the above scheme includes: in the time domain, pilot modulation of the first portion of the first optical signal using the tenth pilot signal to obtain the tenth modulated signal of the first optical signal; in the time domain, pilot modulation of the second portion of the first optical signal using the eleventh pilot signal to obtain the eleventh modulated signal of the first optical signal; in the time domain, pilot modulation of the third portion of the first optical signal using the twelfth pilot signal to obtain the twelfth modulated signal of the first optical signal; in the time domain, pilot modulation of the fourth portion of the first optical signal using the thirteenth pilot signal to obtain the thirteenth modulated signal of the first optical signal; and in the time domain, pilot modulation of the fifth portion of the first optical signal using the fourteenth pilot signal. The system obtains the fourteenth modulated signal of the first optical signal; in the time domain, it performs pilot modulation on the sixth part of the first optical signal using the fifteenth pilot signal to obtain the fifteenth modulated signal of the first optical signal; in the time domain, it performs pilot modulation on the seventh part of the first optical signal using the sixteenth pilot signal to obtain the sixteenth modulated signal of the first optical signal; in the time domain, it performs pilot modulation on the eighth part of the first optical signal using the seventeenth pilot signal to obtain the seventeenth modulated signal of the first optical signal; and based on the tenth modulated signal, the eleventh pilot signal, the twelfth pilot signal, the thirteenth pilot signal, the fourteenth pilot signal, the fifteenth pilot signal, the sixteenth pilot signal, and the seventeenth pilot signal, it obtains the first modulated signal.

[0031] In the above scheme, at least eight portions of the optical signal of the same wavelength within the same channel can be pilot-modulated in the time domain. Specifically, in the time domain, the transmission device can sequentially perform pilot modulation on the first to eighth portions of the first optical signal using the seventeenth pilot signal to the seventeenth pilot signal, and acquire the tenth to seventeenth modulated signals of the first optical signal. This scheme enables pilot modulation of the optical signal within the same channel at a smaller granularity, i.e., a smaller unit length (e.g., unit wavelength width, unit spectral width), resulting in a larger number of modulated signals acquired based on pilot modulation within the same channel, and a smaller interval in length (e.g., wavelength width, spectral width) between adjacent modulated signals. Furthermore, by receiving and detecting the acquired multiple modulated signals, the intensity distribution (e.g., power distribution, i.e., power spectrum) of the multiple modulated signals can be obtained. Simultaneously, due to the smaller length interval between adjacent modulated signals, the above scheme can achieve high-resolution power spectrum detection and detect the power flatness of the pilot signal.

[0032] In some examples, pilot modulation can be performed on optical signals of the same wavelength within the same channel using more pilot signals, thereby further improving the resolution of power spectrum detection and making the detection of power flatness of the pilot signals more accurate. For example, sixteen pilot signals with frequencies and phases of -f1, -f2, -f3, -f4, +f1, +f2, +f3, +f4, +f4, +f3, +f2, +f1, -f4, -f3, -f2, -f1 can be used to pilot modulate sixteen portions of the optical signal within the same channel. As another example, pilot modulation can also be performed on sixteen portions of the optical signal within the same channel using sixteen pilot signals with frequencies and phases of +f1, +f2, +f3, +f4, -f1, -f2, -f3, -f4, -f4, -f3, -f2, -f1, +f4, +f3, +f2, +f1.

[0033] It is easy to understand that the embodiments of this application do not limit the frequency values ​​of the multiple pilot signals. For example, the magnitude relationship between f1, f2, f3, and f4 is not limited, nor are the values ​​of f1, f2, f3, and f4 limited. Similarly, the pilot modulation order of multiple pilot signals with the same phase but different frequencies is not limited. For example, sixteen pilot signals with frequencies and phases of +f1, +f2, +f4, +f3, -f1, -f2, -f4, -f3, -f4, -f3, -f1, -f2, +f4, +f3, +f1, +f2 can be used to pilot modulate sixteen parts of the optical signal in the same channel respectively.

[0034] Of course, the above scheme can also use multiple other pilot signals to perform pilot modulation on the optical signal in the same channel, and the embodiments of this application do not limit this.

[0035] Since optical signals within a certain wavelength range and having a certain center wavelength are typically transmitted within the same channel, the first to eighth optical signals are respectively optical signals within a unit wavelength range and having a certain center wavelength in the first optical signal. The wavelength ranges of the first to eighth optical signals can be the same or different.

[0036] In one possible implementation, the waveform of the pilot signal includes a square wave or a triangular sine wave.

[0037] In the above scheme, optical signals can be modulated using pilot signals of square waves or triangular sine waves. Since the ability of the transmission device to modulate pilot signals of triangular sine shapes is related to its own device performance, in order to ensure the effect of pilot modulation, pilot modulation of optical signals can also be performed using pilot signals of other waveforms. The embodiments of this application do not limit this.

[0038] Secondly, a signal transmission method is provided. This signal transmission method is applied to a second transmission device in an optical network; the second transmission device includes a WSS module, the WSS module includes multiple branch ports and a common port, the common port of the second transmission device being used to connect to an optical fiber; the signal transmission method includes: acquiring a first modulation signal and a second modulation signal received by the common port; wherein the first modulation signal and the second modulation signal have different wavelengths; acquiring the intensity of the first modulation signal, and acquiring the intensity of the second modulation signal; wherein the intensity is used to indicate the optical intensity of the modulation signal.

[0039] In the above scheme, different modulated signals can be acquired, and the intensity of each modulated signal can be obtained. Specifically, the transmission device can acquire the first modulated signal and the second modulated signal received at the common port. The first and second modulated signals have different wavelengths. Further, the transmission device can acquire the intensity of the first modulated signal and the intensity of the second modulated signal. The intensity is used to indicate the optical intensity of the modulated signal. For example, the optical intensity can be characterized by power. Based on the other schemes described above, since the modulated signal is pilot-modulated by different pilot signals of different wavelengths, there is a corresponding relationship between the frequency and power of the modulated signal. For example, a pilot signal with frequency f1 modulates the optical signal with wavelength λ1 in the combined signal, and a pilot signal with frequency f2 modulates the optical signal with wavelength λ2 in the combined signal. Thus, by using the frequency of the modulated signal, the optical signal of the corresponding wavelength and the power of the optical signal after transmission through the optical fiber channel can be determined, thereby determining the optical channel performance of the channel transmitting the optical signal, and thus enabling the detection of the optical channel performance of multiple channels.

[0040] In one possible implementation, the above signal transmission method further includes: acquiring a third modulated signal received at a common port; wherein the first modulated signal, the second modulated signal, and the third modulated signal have different wavelengths; and acquiring the intensity of the third modulated signal.

[0041] The technical effects of the above solution can be referred to the technical effects described in the second aspect above, and will not be repeated here.

[0042] In one possible implementation, obtaining the intensity of the first modulation signal includes: performing photoelectric conversion on the first modulation signal to obtain a first electrical signal; obtaining a first digital signal based on the first electrical signal; and obtaining the intensity of the first modulation signal based on the first digital signal.

[0043] In one possible implementation, obtaining the intensity of the second modulation signal includes: performing photoelectric conversion on the second modulation signal to obtain a second electrical signal; obtaining a second digital signal based on the second electrical signal; and obtaining the intensity of the second modulation signal based on the second digital signal.

[0044] In the above scheme, the intensity of the modulated signal can be obtained by photoelectric conversion of the modulated signal, thereby converting the electrical signal into a digital signal. For example, a pilot signal with frequency f1 modulates the optical signal with wavelength λ1 in the combined signal, and a pilot signal with frequency f2 modulates the optical signal with wavelength λ2 in the combined signal. The power of the electrical signal with frequency f1 is then the power of the modulated optical signal with wavelength λ1, and the power of the electrical signal with frequency f2 is the power of the modulated optical signal with wavelength λ2. Therefore, multiple electrical signals and their powers can be obtained, and the corresponding wavelength of the optical signal and its power after transmission through the optical fiber channel can be determined according to the frequency of the electrical signal. This facilitates the evaluation of the optical channel performance of multiple channels transmitting optical signals of different wavelengths.

[0045] In one possible implementation, the above signal transmission method further includes: in the time domain, pilot modulation of the first modulation signal is performed by the seventh pilot signal to obtain the first optical signal; wherein the seventh pilot signal and the first pilot signal are 180 degrees out of phase and have the same frequency.

[0046] In one possible implementation, the above signal transmission method further includes: in the time domain, pilot modulation of the second modulation signal is performed by the eighth pilot signal to obtain the second optical signal; wherein the eighth pilot signal and the second pilot signal are 180 degrees out of phase and have the same frequency.

[0047] In the above scheme, by modulating the acquired modulation signal with pilot signals of opposite phase and the same frequency, the unmodulated optical signal can be reacquired. Specifically, in the time domain, the first modulation signal is pilot-modulated using the seventh pilot signal to obtain the first optical signal; wherein the seventh pilot signal and the first pilot signal are 180 degrees out of phase and have the same frequency. Similarly, in the time domain, the second modulation signal is pilot-modulated using the eighth pilot signal to obtain the second optical signal; wherein the eighth pilot signal and the second pilot signal are 180 degrees out of phase and have the same frequency. Based on the above other schemes, in the time domain, the first optical signal is intensity-modulated using the first pilot signal to obtain the first modulation signal. In the time domain, the second optical signal is intensity-modulated using the second pilot signal to obtain the second modulation signal. Generally, in order to ensure the normal transmission of services in optical networks (such as DWDM systems) and to facilitate flexible detection of the optical channel performance, it is necessary to erase the pilot signals in the link. Based on the above scheme, by using a pilot signal of the same frequency and in phase but opposite phase (e.g., an inverted pilot signal at frequency f1) to perform pilot modulation on the modulated signal obtained by modulating a pilot signal of the same frequency and in phase (e.g., a pilot signal of the same frequency and in phase), the pilot signal (i.e., the pilot signal of the same frequency f1) can be erased. Therefore, the above scheme can erase the pilot signal, ensuring the normal transmission of optical network services and facilitating flexible testing of the optical channel performance.

[0048] Thirdly, a transmission apparatus is provided. This transmission apparatus is used to perform the signal transmission method as described in any one of the first or second aspects.

[0049] Fourthly, an optical network is provided. The optical network includes: a plurality of optical transmitters, a plurality of optical receivers, and at least one transmission device as described in the third aspect; wherein the transmission device includes a common port and a plurality of branch ports; the branch ports are used to connect to the optical transmitters, and the common port is used to connect to the plurality of optical receivers via optical fibers.

[0050] In one possible implementation, the aforementioned optical network includes a dense wavelength division multiplexing (DWDM) system.

[0051] The technical effects of any of the possible design methods in the third to fourth aspects mentioned above can be referred to the technical effects of any of the design methods in the first and second aspects, and will not be elaborated here. Attached Figure Description

[0052] Figure 1 A schematic diagram of a DWDM system provided for an embodiment of this application;

[0053] Figure 2 A schematic diagram of a multiplexed signal transmission provided for an embodiment of this application;

[0054] Figure 3 A schematic diagram of a coherent optical transmitter provided for an embodiment of this application;

[0055] Figure 4 A schematic diagram of VOA implementation of pilot modulation provided for an embodiment of this application;

[0056] Figure 5 A schematic diagram of a signal transmission method provided for an embodiment of this application;

[0057] Figure 6 A schematic diagram of a signal transmission method provided for another embodiment of this application;

[0058] Figure 7 A schematic diagram of a DWDM system provided for another embodiment of this application;

[0059] Figure 8 A schematic diagram of a WSS provided for an embodiment of this application;

[0060] Figure 9 A schematic diagram of a pilot modulation process provided for an embodiment of this application;

[0061] Figure 10 A schematic diagram of a receiving device provided for an embodiment of this application;

[0062] Figure 11 A schematic diagram of a pilot modulation scheme provided for an embodiment of this application;

[0063] Figure 12 A schematic diagram of a pilot modulation scheme provided for another embodiment of this application;

[0064] Figure 13 A schematic diagram of a pilot modulation scheme provided in another embodiment of this application;

[0065] Figure 14 A schematic diagram of a pilot modulation scheme provided for yet another embodiment of this application;

[0066] Figure 15 A schematic diagram of pilot erasure provided for an embodiment of this application;

[0067] Figure 16 A schematic diagram of a pilot modulation scheme provided for another embodiment of this application;

[0068] Figure 17 This is a schematic diagram of a pilot modulation scheme provided in another embodiment of this application. Detailed Implementation

[0069] This application will present various aspects, embodiments, or features relating to systems that may include multiple devices, components, modules, etc. It should be understood and appreciated that individual systems may include additional devices, components, modules, etc., and / or may not include all devices, components, modules, etc. discussed in conjunction with the accompanying drawings. Furthermore, combinations of these approaches may also be used. It should be noted that in the embodiments of this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0070] The technical terms used in the embodiments of this application are explained as follows:

[0071] DWDM system: An optical network that transmits a set of optical signals with multiple different wavelengths through a single optical fiber is called a DWDM system.

[0072] Pilot tone: refers to a small-amplitude signal superimposed on a single-wavelength optical signal at the transmitting end, used to determine the power of the optical signal superimposed with the pilot tone.

[0073] Optical signal: A signal generated by modulating service data onto an optical carrier and transmitting it along an optical fiber.

[0074] Dummy light (DL): refers to light waves that fill the empty channels in an optical fiber and do not carry service data.

[0075] Stimulated Raman scattering (SRS) effect: It is the effect produced by the coupling of the photoelectric field of a strong laser with the excitation of electrons in atoms, vibrations in molecules, or the lattice in crystals, and has a strong stimulated characteristic.

[0076] Modulated signal: A low-frequency signal derived from the original information. In the embodiments of this application, it refers to the signal generated after the optical signal is modulated by a pilot signal.

[0077] Pilot modulation includes intensity modulation and frequency modulation. Intensity modulation refers to changing the intensity (light strength) of an optical signal through a pilot signal, causing the intensity of the optical signal to change according to the modulation signal. In the embodiments of this application, intensity modulation refers to changing the power of the optical signal through a pilot signal.

[0078] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0079] For example, refer to Figure 1 As shown in the diagram, an embodiment of this application provides a schematic diagram of a DWDM system, illustrating a typical long-distance transmission system. Here, a long-distance transmission system refers to a transmission system with a transmission distance of 600 kilometers (also known as kilometers) or more.

[0080] Combination Figure 1 As shown, the DWDM system includes: multiple optical transmitters (TX) (such as...) Figure 1 (e.g., TX-1 to TX-N and TX-DL), multiple optical receivers (RX) Figure 1 (e.g., RX-1 to RX-N and RX-DL), multiple wavelength selective switches (WSS) (such as...) Figure 1 WSS 101-1 and WSS 101-2 in the series) and multiple amplifiers (such as Figure 1 (as shown in 102-1 to 102-3). All the aforementioned devices are connected via optical fibers. For example, WSS 101-1 and amplifier 102-1, and amplifier 102-1 and amplifier 102-2 are connected via optical fibers.

[0081] in, Figure 1 In the DWDM system, the optical transmitter TX-DL includes a component for transmitting dummy light. Correspondingly, the optical receiver RX-DL is an optical receiver for receiving dummy light.

[0082] Each WSS, such as WSS 101-1 and WSS 101-2, includes one common port and multiple branch ports. Taking WSS 101-1 as an example, the multiple branch ports of WSS 101-1 are used to connect to optical transmitters, and the common port of WSS 101-1 is used to connect to optical fibers.

[0083] The DWDM system can support both downlink and uplink service transmission. Below, we will discuss... Figure 1 The diagram illustrates the downstream service transmission process in a DWDM system:

[0084] Multiple optical transmitters (TX-1 to TX-N) can generate optical carriers of different wavelengths and modulate the service data to be transmitted onto these carriers, thereby generating multiple optical signals of different wavelengths (also known as service signals) and transmitting them to multiple branch ports of WSS 101-1. WSS 101-1 combines the received optical signals of different wavelengths into a combined signal (also known as an optical signal envelope) and transmits it to the optical fiber through a common port. The optical fiber transmits the combined signal to amplifier 102-2, which then amplifies it sequentially through amplifiers 102-2, 102-3, and finally transmits it to the common port of WSS 101-2. WSS 101-2 divides the received combined signal into multiple optical signals of different wavelengths and transmits them to multiple optical receivers (RX-1 to RX-N) through multiple branch ports.

[0085] In a DWDM system, when a multiplexed signal is transmitted along an optical fiber, the multiple optical signals of different wavelengths included in the multiplexed signal are transmitted through different wavelength channels (also called optical channels, or simply channels) in the optical fiber. Therefore, a single optical fiber in a DWDM system typically includes multiple wavelength channels for transmitting optical signals of specific wavelengths. Specifically, when multiple optical signals of different wavelengths included in a multiplexed signal are transmitted along the optical fiber, each wavelength channel is used to transmit an optical signal of a particular wavelength.

[0086] In one possible implementation, the aforementioned DWDM system is a coherent long-distance optical transmission system, in which case the optical transmitters TX-1, TX-2 to TX-N can be implemented as coherent optical transmitters. Optionally, the optical transmitter TX-DL can be implemented as an amplified spontaneous emission (ASE) noise source. For example, the amplifier in the DWDM system can be implemented as an optical amplifier. Of course, for ease of explanation, this is only used as an example... Figure 1 The architecture shown is illustrative and should not be construed as limiting the embodiments of this application. For example, one or more WSSs (e.g., WSSs) may also be installed on the optical fiber in a DWDM system. Figure 1 WSS 101-N (in the context of WSS 101-N).

[0087] As described in the background section, a fault (such as a network failure) in a DWDM system will cause service transmission interruption. However, since the transmission distance of DWDM systems is often long, it is difficult to locate and maintain the fault in a timely manner. Therefore, in order to ensure the stable operation of the DWDM system and reduce interruptions caused by network failures, it is necessary to monitor the optical channel performance of each wavelength channel in the DWDM system simultaneously.

[0088] This technology utilizes optical tagging to detect the performance of multiple wavelength channels in a DWDM system. Specifically, the optical tagging technology includes:

[0089] By using pilot modulation, a specific low-frequency optical signal (also called a pilot signal, measured in megahertz, MHz) is generated for the optical signal transmitted in each channel. The low-frequency optical signals for different channels typically have different frequencies. This generated low-frequency optical signal modulates the optical signal transmitted in the corresponding channel, enabling the pilot-modulated optical signal to be used for tag transmission. Therefore, the pilot-modulated optical signal can also be called the tag signal. This pilot-modulated optical signal is also commonly referred to as the modulation signal. In this way, by modulating the optical signals in different channels with low-frequency optical signals of different frequencies, the modulation signals of different channels have different frequencies, meaning there is a corresponding frequency between each channel and the frequency of the transmitted modulation signal. Therefore, the frequency of the transmitted modulation signal can serve as the tag for the corresponding channel.

[0090] Then, a photodetector (PD) receives and directly detects the pilot-modulated optical signal. The PD's bandwidth is typically only capable of receiving tag signals from a single channel (usually on the order of MHz). However, since optical fibers typically contain multiple channels, and the tag signals for different channels have different frequencies, a receiver (e.g., a photodetector) can simultaneously receive tag signals from multiple channels. The PD then detects the tag signal from a single channel, ultimately monitoring the optical channel performance of all channels in the optical fiber.

[0091] based on Figure 1 As shown, exemplarily, refer to Figure 2 As shown, the process of the combined signal being transmitted sequentially through nodes A, B, and C is illustrated in the diagram.

[0092] A combined signal typically comprises multiple optical signals with different wavelengths. For example, combining... Figure 1 As shown, the combined signal can be generated by combining optical signals with different wavelengths received by WSS 101-1 from multiple optical transmitters.

[0093] Node A can be located at the transmitting end of the DWDM system, i.e., at the location of WSS 101-1. Node B can be located at the receiving end of the DWDM system, i.e., at the location of WSS 101-2. Node C can be located at a certain position on the optical fiber between the transmitting end and the receiving end of the DWDM system, i.e., at a certain position on the optical fiber between WSS 101-1 and WSS 101-2.

[0094] First, combined Figure 2 As shown, the combined signal is pilot-modulated at node A using a pilot signal. For example, the combined signal is modulated using a 50GHz bandwidth polarization division multiplexing (PDM)-16 quadrature amplitude (QAM, QAM) modulated signal (i.e., a 50GHz bandwidth PDM-16QAM signal). The 50GHz-16QAM modulated signal includes multiple modulated signals with different frequencies.

[0095] This 50GHz-16QAM modulation signal can be used to perform low-frequency (e.g., the typical modulation frequency of the modulation signal is 30MHz to 40MHz) intensity modulation on the combined signal, with a modulation depth of 0.01-0.2. The modulation depth is calculated as: (maximum optical signal power - minimum optical signal power) / average optical signal power.

[0096] Then, at node B, between node A and node C, all or part of the pilot-modulated multiplexed signal is detected, thereby monitoring the optical channel performance of all wavelength channels. Optionally, a photodetector can be connected at node B via a coupler to receive a portion of the pilot-modulated multiplexed signal, which is then detected by the photodetector. Further, based on the received portion of the pilot-modulated multiplexed signal, the photodetector can acquire the pilot signal that modulated the multiplexed signal and the transmitted multiplexed signal, and then determine the optical channel performance of the corresponding channel based on the transmitted multiplexed signal. Generally, optical channel performance characterizes transmission parameters such as transmission speed, transmission loss, and transmission bandwidth.

[0097] For example, at point B, a photodetector can acquire the power of multiple optical signals of different wavelengths included in a pilot-modulated multiplexed signal. These multiple optical signals of different wavelengths are transmitted from node A to node B through different channels, and their power is affected by the performance of the optical channels. For instance, if a certain channel has better performance, the power reduction along that channel is less.

[0098] Meanwhile, the multiplexed signal modulated by the pilot at node A will be transmitted normally to node C. That is, while node B determines the optical channel performance of the corresponding channel based on the above process, the service transmission of the DWDM system proceeds normally.

[0099] Therefore, the above solution can monitor the performance of multiple optical channels at a low cost. Furthermore, it ensures normal service transmission while monitoring the optical channel performance.

[0100] Typically, pilot modulation functionality is integrated within the coherent optical transmitter of a DWDM system. Each optical transmitter corresponds to a different center wavelength and can achieve pilot modulation internally using pilot signals of different frequencies. Figure 1 As shown, exemplarily, refer to Figure 3 As shown in the figure, an embodiment of this application provides a schematic diagram of a coherent optical transmitter, illustrating the process of pilot modulation of the coherent optical transmitter at a certain center wavelength.

[0101] Combination Figure 3 As shown, the coherent optical transmitter receives a time-domain digital signal. It then performs a Fast Fourier Transform (FFT) on the received time-domain digital signal, converting it to a frequency-domain signal. Next, the frequency-domain signal is divided into N sub-bands, and an Inverse Fast Fourier Transform (IFFT) is performed to convert them back to a time-domain digital signal. Further, pilot signals of different frequencies (e.g., ...) are used to transmit the signal. Figure 3 Pilot signals 1 and 2 modulate the time-domain digital signal, respectively, to achieve pilot modulation. Finally, the coherent optical transmitter combines multiple pilot-modulated time-domain digital signals and converts them into analog signals via a digital-to-analog converter (DAC). Further, the optical transmitter modulates the analog signal onto an optical carrier to generate and output an optical signal.

[0102] Based on the above, coherent optical transmitters can perform pilot modulation on signals.

[0103] However, the above scheme can only be deployed at the transmitting end of the DWDM system, and cannot perform pilot modulation of the signal outside the coherent optical transmitter (e.g., on the link between two nodes), so it has poor flexibility.

[0104] Furthermore, the above-mentioned scheme cannot perform pilot modulation on spurious light, and therefore cannot be used in DWDM systems (e.g., Figure 1 In the DWDM system shown, the optical communication performance of all channels is monitored when spurious light is transmitted.

[0105] It should be understood that Figure 3 This is an exemplary architecture and should not be construed as limiting the embodiments of this application.

[0106] In some examples, optical power monitoring (OPM) can be used to detect spurious light. However, this method requires detecting each channel by wavelength to identify spurious light propagating in each channel before detecting it. Therefore, it suffers from problems such as long scanning time and high cost, making it difficult to apply widely.

[0107] To address the problem of the inability to perform pilot modulation on spurious light, a variable optical attenuator (VOA) is typically used to achieve pilot modulation.

[0108] based on Figure 1 The architecture shown is exemplary, referencing Figure 4 The diagram illustrates the scheme in simple detail. Specifically, in conjunction with... Figure 4 As shown, this scheme first receives a combined signal containing multiple optical signals of different wavelengths from multiple optical transmitters (such as optical transmitters TX-1 to TX-N and TX-DL). Then, a wavelength division device 401 demultiplexes the combined signal to obtain multiple optical signals of different wavelengths. Finally, multiple fast-adjustable optical attenuators (such as...) are used to... Figure 4 VOA 402-1 to VOA 402-N in the diagram modulate multiple optical signals of different wavelengths using pilot modulation. Finally, the multiple pilot-modulated optical signals of different wavelengths are combined and output.

[0109] Among them, different fast tunable optical attenuators can achieve pilot modulation of multiple optical signals of different wavelengths by pilot signals of different frequencies.

[0110] The wavelength division multiplexing device 401 can be implemented by a wavelength division multiplexing (WDM). However, for ease of explanation, only one example is used here. Figure 4 The architecture shown is for illustrative purposes only and should not be construed as limiting the embodiments of this application.

[0111] based on Figure 4 The scheme shown can achieve pilot modulation of optical signals of different wavelengths.

[0112] However, implementing the above solution requires the introduction of wavelength division multiplexing (WDM) devices, which introduces insertion loss. Furthermore, because this solution requires the deployment of multiple fast-tunable optical attenuators, it results in high cost and large size.

[0113] To address the problem of not being able to perform pilot modulation on spurious light, pilot modulation can usually be achieved through signal encoding.

[0114] Specifically, this method can generate a corresponding tag code based on the channel type of the transmitted spurious light. This tag code is used to identify the channel of the transmitted spurious light. The channel type includes: temporary filling type corresponding to the channel of temporary filling spurious light, and normal filling type corresponding to the channel of continuous filling spurious light.

[0115] Then, in the frequency domain, pilot modulation is performed on a specific dummy light according to the generated tag code via WSS. This establishes a correspondence between the channel transmitting the dummy light and the frequency modulated by that dummy light; that is, the modulated frequency corresponds to the tag code modulated by the channel transmitting the dummy light. Furthermore, at the receiving end, the channel can be identified according to the tag code modulated by the channel.

[0116] Therefore, the above scheme uses pilot modulation on the fake light according to the generated tag code to identify the corresponding channel.

[0117] However, this scheme only modulates the tag corresponding to the spurious light in the frequency domain, thus it can only identify the channel type transmitting the spurious light based on the tag encoding. Since it cannot detect the intensity of the transmitted spurious light, this scheme is difficult to monitor the optical channel performance of the channel.

[0118] Based on the above, there is currently a lack of technical solutions that can effectively monitor the performance of optical channels with multiple wavelengths.

[0119] To address the above issues, for example, refer to Figure 5 As shown, embodiments of this application provide a signal transmission method capable of pilot modulation of optical signals of different wavelengths using the same transmission device. This signal transmission method can be applied to transmission devices in optical networks, which include a WSS module. The transmission module can be the WSS module itself, or it can be implemented by a device integrating a WSS module; embodiments of this application do not limit this. The following will be combined with... Figure 5 The signal transmission method provided in the embodiments of this application will be described in detail below. In the following embodiments, the example of a transmission device in an optical network executing the signal transmission method provided in the embodiments of this application is used for description, and this should not be construed as limiting the embodiments of this application.

[0120] It should be noted that, referring to Figure 1 As shown in the architecture, WSS 101-1 in the DWDM system can be used to execute the methods provided in the following embodiments of this application. Alternatively, a device integrating WSS 101-1 can also be used to execute the methods provided in the following embodiments of this application. Of course, other devices or equipment capable of performing similar functions can also execute the following signal transmission method, and the embodiments of this application do not limit this. The signal transmission method includes steps 501 to 506, which are described in detail below.

[0121] Step 501: Acquire the first optical signal and the second optical signal.

[0122] For example, taking the transmission device WSS 101-1 as an example, combined with Figure 1 As shown, the WSS 101-1 in the DWDM system acquires a first optical signal through a first branch port and a second optical signal through a second branch port. The first and second optical signals have different wavelengths.

[0123] Optional, combined Figure 1 As shown, the first optical signal includes: an optical signal transmitted by any one of the optical transmitters TX-1 to TX-N, or a dummy light transmitted by optical transmitter TX-DL. Similarly, the second optical signal includes: an optical signal transmitted by any one of the optical transmitters TX-1 to TX-N, or a dummy light transmitted by optical transmitter TX-DL.

[0124] It is easy to understand that in a DWDM system, optical signals of different wavelengths will be transmitted through different channels in the fiber when they are transmitted along the same optical fiber.

[0125] Step 502: Perform pilot modulation on the first optical signal to obtain a first modulation signal, and perform pilot modulation on the second optical signal to obtain a second modulation signal.

[0126] Specifically, taking the WSS 101-1 transmission device as an example, combined with... Figure 1 As shown, in the DWDM system, WSS 101-1 performs pilot modulation on the first optical signal to obtain the first modulation signal, and performs pilot modulation on the second optical signal to obtain the second modulation signal.

[0127] The embodiments of this application do not limit the specific method of pilot modulation of optical signals within the same channel. Exemplary methods for pilot modulation of optical signals include the following:

[0128] (Scheme 1) Pilot modulation of the first optical signal includes: intensity modulation of the first optical signal in the time domain; pilot modulation of the second optical signal includes: intensity modulation of the second optical signal in the time domain.

[0129] (Scheme 2) Pilot modulation of the first optical signal in the time domain includes: intensity modulation of the first optical signal by the first pilot signal in the time domain; pilot modulation of the second optical signal in the time domain includes: intensity modulation of the second optical signal by the second pilot signal in the time domain; wherein the first pilot signal and the second pilot signal have different frequencies.

[0130] (Scheme 3) Pilot modulation of the first optical signal in the time domain includes: in the time domain, pilot modulation of the first part of the optical signal in the first optical signal is performed by the third pilot signal to obtain the first part of the modulated signal of the first optical signal; in the time domain, pilot modulation of the second part of the optical signal in the first optical signal is performed by the fourth pilot signal to obtain the second part of the modulated signal of the first optical signal; and a first modulated signal is obtained based on the first part of the modulated signal and the second part of the modulated signal; wherein the phase of the third pilot signal is 180 degrees different from the phase of the fourth pilot signal, and the third pilot signal and the fourth pilot signal have the same frequency.

[0131] To further improve the SRS suppression effect of the above scheme, SRS crosstalk can be suppressed by modulating multiple pairs of anti-phase pilot signals with the same frequency (i.e., multiple sets of pilot signals with opposite phases and the same frequency) in the same channel. Specifically, when different parts of the optical signal in the same channel are pilot modulated by multiple pairs of anti-phase pilot signals (e.g., including), the pilot signals modulated by two non-adjacent parts of the optical signal have opposite phases.

[0132] For example, the same channel can be modulated by two pairs of anti-phase pilots (including two sets of pilot signals with opposite phases and the same frequency, such as the first pair of anti-phase pilots and the second pair of anti-phase pilots).

[0133] Alternatively, for different channels, modulation can be achieved separately for each channel using anti-phase pilot pairs with different frequencies.

[0134] (Scheme 4) Pilot modulation of the first optical signal in the time domain includes: in the time domain, pilot modulation of the first part of the optical signal in the first optical signal using the fifth pilot signal to obtain the third part of the modulation signal of the first optical signal; in the time domain, pilot modulation of the second part of the optical signal in the first optical signal using the sixth pilot signal to obtain the fourth part of the modulation signal of the first optical signal; and obtaining the first modulation signal based on the third part of the modulation signal and the fourth part of the modulation signal; wherein the fifth pilot signal and the sixth pilot signal have different frequencies.

[0135] (Scheme 5) Performing pilot modulation on the first optical signal in the time domain to obtain a first modulation signal includes: in the time domain, performing pilot modulation on a first portion of the first optical signal using a seventh pilot signal to obtain a seventh portion modulation signal of the first optical signal; in the time domain, performing pilot modulation on a second portion of the first optical signal using an eighth pilot signal to obtain an eighth portion modulation signal of the first optical signal; and in the time domain, performing pilot modulation on a third portion of the first optical signal using a ninth pilot signal to obtain a ninth portion modulation signal of the first optical signal; based on the seventh portion... The modulation signal is obtained by dividing the modulation signal into an eighth part and a ninth part; wherein the wavelength of the first part of the optical signal is shorter than the wavelength of the second part of the optical signal, and the wavelength of the second part of the optical signal is shorter than the wavelength of the third part of the optical signal; or, the wavelength of the second part of the optical signal is shorter than the wavelength of the third part of the optical signal; the wavelength of the first part of the optical signal is longer than the wavelength of the third part of the optical signal; the seventh pilot signal and the eighth pilot signal are 180 degrees out of phase, and the seventh pilot signal and the eighth pilot signal have the same frequency; the seventh pilot signal and the ninth pilot signal have different frequencies.

[0136] In some examples, based on the above scheme, pilot modulation of the optical signal within the same channel can be performed separately using multiple pilot signals comprising more sets of anti-phase pilot pairs. For example, pilot modulation of five parts of the optical signal within the same channel can be performed separately using five pilot signals with frequencies and phases of -f1, -f1, +f1 (i.e., the first set of anti-phase pilot pairs) and +f1, -f1 (i.e., the second set of anti-phase pilot pairs). As another example, pilot modulation of five parts of the optical signal within the same channel can be performed separately using five pilot signals with frequencies and phases of +f1, -f1, +f1 (i.e., the first set of anti-phase pilot pairs) and +f1, -f1 (i.e., the second set of anti-phase pilot pairs).

[0137] (Solution 6) Performing pilot modulation on the first optical signal in the time domain to obtain a first modulation signal includes: in the time domain, performing pilot modulation on a first portion of the first optical signal using a tenth pilot signal to obtain a tenth modulation signal of the first optical signal; in the time domain, performing pilot modulation on a second portion of the first optical signal using an eleventh pilot signal to obtain an eleventh modulation signal of the first optical signal; and in the time domain, performing pilot modulation on a third portion of the first optical signal using a twelfth pilot signal to obtain a twelfth modulation signal of the first optical signal. In the time domain, the fourth part of the first optical signal is pilot-modulated using the thirteenth pilot signal to obtain the thirteenth modulated signal of the first optical signal; in the time domain, the fifth part of the first optical signal is pilot-modulated using the fourteenth pilot signal to obtain the fourteenth modulated signal of the first optical signal; in the time domain, the sixth part of the first optical signal is pilot-modulated using the fifteenth pilot signal to obtain the fifteenth modulated signal of the first optical signal; in the time domain, the seventh part of the first optical signal is pilot-modulated using the sixteenth pilot signal to obtain the thirteenth modulated signal of the first optical signal; A portion of the optical signal is pilot-modulated to obtain the sixteenth modulated signal of the first optical signal; in the time domain, the eighth portion of the first optical signal is pilot-modulated using the seventeenth pilot signal to obtain the seventeenth modulated signal of the first optical signal; based on the tenth modulated signal, the eleventh pilot signal, the twelfth pilot signal, the thirteenth pilot signal, the fourteenth pilot signal, the fifteenth pilot signal, the sixteenth pilot signal, and the seventeenth pilot signal, the first modulated signal is obtained; wherein the wavelengths of the first to eighth portions of the optical signal are distributed in ascending order. The tenth, twelfth, and fifteenth pilot signals have a first frequency, while the eleventh, thirteenth, fourteenth, and sixteenth pilot signals have a second frequency. The first and second frequencies are different. The tenth, eleventh, sixteenth, and seventeenth pilot signals have the same phase. The twelfth, thirteenth, fourteenth, and fifteenth pilot signals have the same phase. The eleventh and twelfth pilot signals are 180 degrees out of phase.

[0138] In some examples, pilot modulation can be performed on optical signals of the same wavelength within the same channel using more pilot signals, thereby further improving the resolution of power spectrum detection and making the detection of power flatness of the pilot signals more accurate. For example, sixteen pilot signals with frequencies and phases of -f1, -f2, -f3, -f4, +f1, +f2, +f3, +f4, +f4, +f3, +f2, +f1, -f4, -f3, -f2, -f1 can be used to pilot modulate sixteen portions of the optical signal within the same channel. As another example, pilot modulation can also be performed on sixteen portions of the optical signal within the same channel using sixteen pilot signals with frequencies and phases of +f1, +f2, +f3, +f4, -f1, -f2, -f3, -f4, -f4, -f3, -f2, -f1, +f4, +f3, +f2, +f1.

[0139] It should be noted that the embodiments of this application do not limit the frequency values ​​of the multiple pilot signals. For example, the magnitude relationship between f1, f2, f3, and f4 is not limited, nor are the values ​​of f1, f2, f3, and f4 limited. Similarly, the pilot modulation order of multiple pilot signals with the same phase but different frequencies is not limited. For example, sixteen pilot signals with frequencies and phases of +f1, +f2, +f4, +f3, -f1, -f2, -f4, -f3, -f4, -f3, -f1, -f2, +f4, +f3, +f1, +f2 can be used to pilot modulate sixteen parts of the optical signal in the same channel respectively. Of course, the above scheme can also use other multiple pilot signals to pilot modulate the optical signal in the same channel separately, and the embodiments of this application do not limit this.

[0140] It is easy to understand that pilot modulation of the first or second optical signal can also be achieved through other methods, and the embodiments of this application do not limit this.

[0141] Step 503: Transmit the first modulation signal and the second modulation signal to the optical fiber.

[0142] Specifically, taking the WSS 101-1 transmission device as an example, combined with... Figure 1 As shown, in the DWDM system, WSS 101-1 transmits the first and second modulation signals to the optical fiber through a common port.

[0143] Based on steps 501 to 503 above, the signal transmission method provided in the embodiments of this application further includes the following steps:

[0144] Step 504: Obtain the third optical signal.

[0145] Specifically, taking the WSS 101-1 transmission device as an example, combined with... Figure 1 As shown, the WSS 101-1 in the DWDM system acquires the third optical signal through the third branch port. The wavelengths of the first, second, and third optical signals are different.

[0146] Optional, combined Figure 1 As shown, the third optical signal includes the optical signal transmitted by any one of the optical transmitters TX-1 to TX-N. For example, the third optical signal can be a dummy light transmitted by optical transmitter TX-DL.

[0147] Step 505: Perform pilot modulation on the third optical signal to obtain the third modulation signal.

[0148] Specifically, taking the WSS 101-1 transmission device as an example, combined with... Figure 1 As shown, WSS 101-1 in the DWDM system performs pilot modulation on the third optical signal to obtain the third modulation signal.

[0149] Step 506: Transmit the third modulation signal to the optical fiber.

[0150] Specifically, taking the WSS 101-1 transmission device as an example, combined with... Figure 1 As shown, in the DWDM system, WSS 101-1 transmits the third modulation signal to the optical fiber through the common port.

[0151] Based on steps 501 to 506 above, multiple wavelengths of optical signals can be pilot-modulated separately using the same transmission device, which facilitates the determination of the optical channel performance of multiple channels transmitting multiple modulated signals. Furthermore, this solution eliminates the need to deploy multiple additional devices or modules in the optical network for pilot modulation, thereby reducing insertion loss and ensuring the transmission quality of the optical network.

[0152] For example, refer to Figure 6 As shown, embodiments of this application provide a signal transmission method capable of obtaining the intensity of an optical signal based on a modulation signal and determining the optical channel performance of the channel transmitting the optical signal. This signal transmission method can be applied to a transmission device in an optical network, the transmission device including a WSS module. The transmission module can be the WSS module itself, or it can be implemented by a device integrating a WSS module; embodiments of this application do not limit this. The following will be combined with... Figure 6 The signal transmission method provided in the embodiments of this application will be described in detail below. In the following embodiments, the example of a transmission device in an optical network executing the signal transmission method provided in the embodiments of this application is used for description, and this should not be construed as limiting the embodiments of this application.

[0153] It should be noted that, referring to Figure 1 The architecture shown indicates that the WSS 101-N in the DWDM system can be used to execute the methods provided in the following embodiments of this application. Alternatively, a device integrating the WSS 101-N can also be used to execute the methods provided in the following embodiments of this application. Of course, other devices or equipment capable of performing similar functions can also execute the following signal transmission method, and the embodiments of this application do not limit this. The signal transmission method includes steps 601 to 604, which are described in detail below.

[0154] Step 601: Obtain the first modulation signal and the second modulation signal.

[0155] For example, taking the WSS 101-N transmission device as an example, combined with Figure 1 As shown, the WSS 101-N in the DWDM system acquires a first modulation signal and a second modulation signal through a common port. The first modulation signal and the second modulation signal have different wavelengths.

[0156] In some examples, WSS 101-N can also erase pilot modulation. Combining with step 502 above, WSS 101-1 modulates the first optical signal in the time domain using the first pilot signal. Therefore, based on step 601, the erasure of pilot modulation by WSS 101-N includes: in the time domain, pilot modulation of the acquired first modulation signal using another pilot signal (e.g., identified as the seventh pilot signal) to acquire the first optical signal. The ninth pilot signal is 180 degrees out of phase with the first pilot signal, and the seventh pilot signal has the same frequency as the first pilot signal.

[0157] Similarly, in conjunction with step 502 above, WSS 101-1 modulates the second optical signal in the time domain using the second pilot signal. Based on step 601, the erasure of the pilot modulation by WSS 101-N includes: in the time domain, pilot modulation of the second modulation signal using another pilot signal (e.g., identified as the eighth pilot signal) to obtain the second optical signal. The eighth pilot signal and the second pilot signal are 180 degrees out of phase, and have the same frequency.

[0158] Step 602: Obtain the intensity of the first modulation signal and the intensity of the second modulation signal.

[0159] For example, taking the WSS 101-N transmission device as an example, combined with Figure 1 As shown, the WSS 101-N in the DWDM system acquires the intensity of the first modulation signal and the intensity of the second modulation signal. The intensity is used to indicate the optical intensity of the modulation signal.

[0160] Typically, light intensity can be characterized by power.

[0161] In one possible implementation, obtaining the intensity of the first modulation signal includes: performing photoelectric conversion on the first modulation signal to obtain a first electrical signal; obtaining a first digital signal based on the first electrical signal; and obtaining the intensity of the first modulation signal based on the first digital signal.

[0162] Optionally, obtaining the intensity of the second modulation signal includes: performing photoelectric conversion on the second modulation signal to obtain a second electrical signal; obtaining a second digital signal based on the second electrical signal; and obtaining the intensity of the second modulation signal based on the second digital signal.

[0163] Based on steps 601 and 602 above, the signal transmission method provided in the embodiments of this application further includes the following steps:

[0164] Step 603: Obtain the third modulation signal.

[0165] For example, taking the WSS 101-N transmission device as an example, combined with Figure 1 As shown, the WSS 101-N in the DWDM system acquires the third modulation signal through a common port. The first, second, and third modulation signals have different wavelengths.

[0166] Step 604: Obtain the intensity of the third modulation signal.

[0167] For example, taking the WSS 101-N transmission device as an example, combined with Figure 1 As shown, the WSS 101-N in the DWDM system acquires the strength of the third modulation signal. The specific method for acquiring the strength of the third modulation signal can refer to the method described in step 602 above for acquiring the strength of the first modulation signal or the method for acquiring the strength of the second modulation signal.

[0168] Based on steps 601 to 604 above, the transmission device can determine the intensity of different modulation signals based on different modulation signals, and then determine the optical channel performance of multiple channels transmitting different modulation signals, thereby realizing the detection of the optical channel performance of multiple channels.

[0169] The following will combine Figure 1 The architecture shown will be used to specifically describe the signal transmission method provided by the above-described method embodiments of this application.

[0170] Based on the above signal transmission method, combined with Figure 1 The architecture shown is exemplary, referencing Figure 7 As shown, an embodiment of this application provides a schematic diagram of a DWDM system, illustrating a typical coherent long-distance optical transmission system. Based on Figure 1 As shown, specifically, in combination Figure 7 As shown, the DWDM system includes, Figure 1 In addition to the devices shown, it also includes: multiple couplers (such as...) Figure 7 Coupler 103-1 and coupler 103-2 in the middle) and receiving device (such as Figure 7 (Receiver 104-1 and Receiver 104-2 in the middle).

[0171] In one possible implementation, the wavelength range of the N optical transmitters in the DWDM system covers the entire C+L band, that is, the wavelength range of the light waves output by the N optical transmitters is 1524 nanometers (nm) to 1626 nm.

[0172] Multiple couplers (including coupler 103-1 and coupler 103-2) are disposed on the optical fibers between multiple optical transmitters and multiple optical receivers, and any coupler is also used to connect a receiving device. For example, coupler 103-1 is used to connect receiving device 104-1. Of course, for ease of explanation, only one example is used here. Figure 7 The architecture shown is for illustrative purposes only and should not be construed as limiting the embodiments of this application.

[0173] Among them, reference Figure 8 As shown, Figure 7 The WSS (including WSS 101-1 and WSS 101-2) in the DWDM system shown includes a diffraction grating (labeled 601 in the figure) for wavelength division and a spatial light modulator (SLM) (labeled 602 in the figure) for pilot modulation.

[0174] In one possible implementation, the aforementioned WSS can be implemented using a liquid crystal on silicon (LCOS) based WSS. Based on this, the SLM in the WSS can be implemented using LCOS. Specifically, LCOS can control the propagation direction of the light beam by modulating the phase of the incident light, supports intensity modulation of incident light at various wavelengths, and has the ability to modulate low-frequency signals (LCOS supports intensity modulation of incident light based on pilot signals in the frequency range of 0Hz to 120Hz).

[0175] Of course, for ease of explanation, this is only used as an example. Figure 8 The architecture shown is illustrative and should not be construed as limiting the embodiments of this application. For example, one or more of the optical transmitter functions described above can also be implemented by an optical transform unit (OTU).

[0176] Specifically, in combination Figure 7 As shown, the transmission process in the downstream direction is taken as an example:

[0177] Multiple optical transmitters (i.e., optical transmitters TX-1 to TX-N) can generate optical carriers of different wavelengths respectively, and modulate the service data to be transmitted into the generated optical carriers, thereby generating multiple optical signals of different wavelengths (also known as service signals) and sending them to multiple branch ports of WSS 101-1 respectively.

[0178] WSS 101-1 uses pilot signals of different frequencies to perform pilot modulation on multiple optical signals of different wavelengths included in the received combined signal (i.e., the optical signal envelope) (refer to Scheme 2 in step 502).

[0179] Specifically, refer to Figure 8 As shown, WSS 101-1 receives optical signals of multiple center wavelengths from multiple optical transmitters through multiple branch ports. The diffraction grating 601 in WSS 101-1 can transmit optical signals of different center wavelengths to different positions of SLM 602 according to the wavelength (see reference). Figure 8 The SLM 602, as shown in the diagram, corresponds to the positions of the areas marked by different lines. The SLM 602 can perform pilot modulation of optical signals of different wavelengths in the time domain using pilot signals of different frequencies. Specifically, the SLM 602 can perform intensity modulation (i.e., power modulation) of optical signals with different center wavelengths in the time domain using pilot signals of different frequencies. Furthermore, the WSS 101-1 combines the modulated optical signals of different center wavelengths and outputs them to the optical fiber through a common port.

[0180] Typically, the SLM 602 uses multiple low-frequency pilot signals to modulate different optical signals. These low-frequency pilot signals are those with frequencies between 30MHz and 50MHz. For example, if WSS 101-1 is implemented using an LCOS-based WSS, then the LCOS in WSS 101-1 can control the propagation direction of the beam by modulating the phase of the incident light, supporting intensity modulation of the incident light at each center wavelength.

[0181] For example, in combination Figure 9 As shown in (1), the power distribution of the combined signal (i.e., the optical signal envelope) acquired by WSS 101-1 is illustrated; where the horizontal axis represents time and the vertical axis represents power. Typically, the optical signal envelope acquired by WSS 101-1 includes optical signals of different wavelengths, and the power of optical signals of different wavelengths is almost the same.

[0182] Combination Figure 9As shown in (2), the power distribution of the optical signal envelope modulated by WSS 101-1 is illustrated; where the horizontal axis represents time and the vertical axis represents power. Since WSS 101-1 can achieve pilot modulation of optical signals of different wavelengths through pilot signals of different frequencies, the power of optical signals of different wavelengths included in the modulated optical signal envelope will no longer be consistent.

[0183] Then, the WSS 101-1 combines the modulated optical signals of different wavelengths into a combined signal and outputs it to the optical fiber. The multiple optical signals of different wavelengths included in the combined signal are transmitted along the optical fiber through different channels according to their wavelengths. For example, the signal with wavelength λ1 in the combined signal is transmitted through the first channel of the optical fiber, and the signal with wavelength λ2 in the combined signal is transmitted through the second channel of the optical fiber.

[0184] Furthermore, the optical fiber transmits the multiplexed signal to amplifier 102-2. The multiplexed signal is then amplified sequentially by amplifiers 102-2, 102-3, and 102-3 before being transmitted to the common port of WSS 101-2. WSS 101-2 then splits the received multiplexed signal into multiple optical signals of different wavelengths, which are transmitted to multiple optical receivers (i.e., optical receivers RX-1 to RX-N) through multiple branch ports.

[0185] In one possible implementation, the coupler (including coupler 103-1 and coupler 103-2) is capable of separating a portion of the pilot-modulated multiplexed signal transmitted in the optical fiber and transmitting it to the receiving device (including receiving device 104-1 and receiving device 104-2). The receiving device is capable of receiving the separated portion of the multiplexed signal and detecting the pilot-modulated multiplexed signal to determine the intensity of the multiple optical signals of different wavelengths included in the multiplexed signal, thereby determining the optical channel performance of the channel transmitting the multiplexed signal.

[0186] Optionally, the coupler can be implemented using a WSS, that is, receiving the multiplexed signal through the common port of the WSS. Alternatively, the coupler can be implemented using an optical coupler with an unequal ratio, such as an optical coupler with a splitting ratio of 1:99.

[0187] In one possible implementation, refer to Figure 10 As shown, the receiving device includes a photodetector (labeled 201 in the figure), an amplifier (e.g., a transimpedance amplifier (TIA)) (labeled 202 in the figure), and a digital signal processing (DSP) chip (labeled 203 in the figure). Of course, for ease of explanation, only [the specific example shown here] is used. Figure 10The architecture shown is for illustrative purposes only and should not be construed as limiting the embodiments of this application.

[0188] Based on this, a portion (e.g., 1%) of the pilot-modulated multiplexed signal is transmitted to the receiving device through the common port or coupler of the WSS, converted into an electrical signal by PD processing, amplified by TIA, and finally transmitted to the DSP chip. Since the pilot signals used for pilot modulation of optical signals of different wavelengths have different frequencies, the DSP chip uses relevant algorithms to obtain multiple electrical signals corresponding to the different wavelengths of optical signals included in the pilot-modulated multiplexed signal, as well as the power of these multiple electrical signals. For example, the DSP chip can determine the electrical signal corresponding to any wavelength of optical signal in the multiplexed signal, and the power of that electrical signal.

[0189] Furthermore, since pilot modulation of optical signals of different wavelengths is achieved at the transmitting end using pilot signals of different frequencies, there is a corresponding relationship between the frequency and power of the optical signal of a certain wavelength received by the receiving device. For example, a pilot signal with frequency f1 modulates the optical signal with wavelength λ1 in the combined signal, and a pilot signal with frequency f2 modulates the optical signal with wavelength λ2 in the combined signal. Therefore, the power of the electrical signal with frequency f1 obtained by the DSP chip is the power of the modulated optical signal with wavelength λ1, and the power of the electrical signal with frequency f2 is the power of the modulated optical signal with wavelength λ2. Thus, the DSP chip can obtain multiple electrical signals corresponding to the same wavelength of optical signal and the power of these multiple electrical signals. Based on the frequency of the electrical signals, it can determine the corresponding wavelength of optical signal and its corresponding power, thereby determining the channel for transmitting the optical signal of that wavelength and the transmission parameters of that channel, and ultimately determining the optical channel performance of multiple channels transmitting optical signals of different wavelengths.

[0190] Therefore, the above scheme can determine the power of optical signals of different wavelengths, thereby enabling the monitoring of the optical channel performance of each wavelength channel in the DWDM system.

[0191] Because the SRS effect generates extremely high SRS crosstalk for low-frequency signals, pilot modulation of optical signals using low-frequency pilot signals significantly impacts the transmission quality of the modulated optical signal along the channel. This makes it impossible to accurately determine the power of optical signals at different wavelengths, thus affecting the detection of the optical channel's performance. Therefore, when performing pilot modulation, a scheme of modulating inverse pilot pairs of the same frequency within the same channel can be used (refer to scheme 3 in step 502) to suppress SRS crosstalk.

[0192] Here, a pilot pair can refer to a set of pilot signals. For example, a pilot pair can include two pilot signals with different frequencies or different phases. Pilot pairs can include, but are not limited to, one or more pairs, such as two or more pairs. Modulating anti-phase pilot pairs within the same channel can include: modulating different parts of the optical signal within the same channel separately using a set of pilot pairs with the same frequency but opposite phases.

[0193] Reference Figure 11 As shown, taking an optical signal with a wavelength range of 43 nm from 193 MHz (THz) to 193.2 THz as an example, there are four channels. Here, wavelength range refers to the amount of wavelength variation within a certain frequency range.

[0194] The following pilot modulation process can be achieved through Figure 8 The architecture shown is implemented.

[0195] This section only uses Figure 11 The architecture shown is for illustrative purposes only and should not be construed as limiting the embodiments of this application.

[0196] Combination Figure 11 As shown in (1), a total of four pilot signals with frequencies from f1 to f4 were modulated within a wavelength width of 43 nm. During modulation, each pilot signal occupies a wavelength width of 10.75 nm (i.e., it is used for pilot modulation of an optical signal with a unit wavelength width of 10.75 nm). The horizontal axis represents wavelength in nanometers (nm), and the vertical axis represents power.

[0197] Specifically, taking the modulation of an optical signal within the first unit wavelength width of 1524nm-1534.15nm using a pilot signal with frequency f1 as an example, the optical signal corresponding to the wavelength width range of 1524nm-1526.6875nm can be modulated using an inverted pilot signal sin(2πf1t+π), and the optical signal corresponding to the wavelength width range of 1526.6875nm-1529.375nm can be modulated using a positive-phase pilot signal sin(2πf1t). Since the phase of the inverted pilot signal is opposite to that of the positive-phase pilot signal (i.e., opposite signs and 180 degrees out of phase), the inverted and positive-phase pilot signals within the 1524nm-1529.375nm wavelength width range form an inverted pilot pair, i.e., the first inverted pilot pair. It is not difficult to understand that...

[0198] Similarly, the optical signal corresponding to the wavelength range of 1529.375nm-1532.0625nm is modulated by the positive-phase pilot signal sin(2πf1t), and the optical signal corresponding to the wavelength range of 1532.0625nm-1534.75nm is modulated by the negative-phase pilot signal sin(2πf1t+π). Thus, the negative-phase pilot signal and the positive-phase pilot signal within the wavelength range of 1529.375nm-1534.75nm constitute a negative-phase pilot pair, i.e., the second negative-phase pilot pair.

[0199] Furthermore, a pilot signal with a frequency of f2 can be used to modulate the optical signal within the second unit wavelength width. For example, the wavelength width range of 1534.75nm-1537.4375nm modulates the inverted pilot signal sin(2πf2t+π), the wavelength width range of 1537.4375nm-1540.125nm modulates the positive pilot signal sin(2πf2t), the wavelength width range of 1540.125nm-1542.8125nm modulates the positive pilot signal sin(2πf2t), and the wavelength width range of 1542.8125nm-1545.5nm modulates the inverted pilot signal sin(2πf2t+π).

[0200] It is easy to understand that the pilot signals modulated by optical signals in the same channel (CH) have the same frequency. For example, refer to... Figure 11 As shown in (1), when pilot modulation is performed on an optical signal with a wavelength range of 1524nm-1534.75nm, the frequency of the pilot signal is f1, denoted as CH-m(f1). When pilot modulation is performed on an optical signal with a wavelength range of 1534.75nm-1545.5nm, the frequency of the pilot signal is f2, denoted as CH-m(f2).

[0201] Similarly, the process of modulating an optical signal with a wavelength range of 1545.5nm-1556.25nm using a pilot signal with a frequency of f3, and the process of modulating an optical signal with a wavelength range of 1556.25nm-1567nm using a pilot signal with a frequency of f4, can be referred to the above process.

[0202] Combination Figure 11As shown in (2), the coupler (e.g., WSS or comb filter) can filter out the positive-phase signal from the combined signal with a wavelength range of 43 nm between 193 THz and 193.2 THz. Specifically, the optical signal corresponds to the wavelength ranges of 1526.6875 nm - 1529.375 nm, 1529.375 nm - 1532.0625 nm, 1537.4375 nm - 1540.125 nm, and 1540.125 nm - 1542.8125 nm, and output it. Here, the horizontal axis represents the wavelength in nanometers (nm), and the vertical axis represents the power.

[0203] Of course, the inverted signal can also be filtered out and output using a coupler, but the embodiments of this application do not limit this.

[0204] Furthermore, combined Figure 11 (2) and Figure 11 As shown in (3), the signal filtered out by the coupler (e.g., only the filtered positive phase signal) will be output to the PD.

[0205] Because pilot modulation of optical signals of different wavelengths is achieved at the transmitting end using pilot signals of different frequencies, there is a corresponding relationship between the frequency and power of an optical signal of a certain wavelength received by the receiving device. Therefore, optical signals corresponding to different wavelength ranges within the same channel are modulated at different frequencies.

[0206] Since only single-phase (including positive or negative phase) signals are transmitted to the PD, and the amplitudes of the positive and negative pilot signals are the same, the PD can determine the power of the optical signals after transmission based on the frequencies modulated by the optical signals of different wavelength ranges in the single-phase signal. Furthermore, by using the power of the optical signals after transmission of different wavelength ranges in the single-phase signal, the power of the optical signals transmitted in the entire channel can be determined.

[0207] For example, combining Figure 11 As shown in (1), the power of optical signals with different wavelength widths in the positive phase signal after transmission is the same as the power of optical signals with different wavelength widths in the negative phase signal after transmission. Therefore, by using the power of optical signals with different wavelength widths in the positive phase signal after transmission, the power of optical signals with different wavelength widths in the negative phase power signal after transmission can be determined, thereby determining the power of the optical signals transmitted in the entire channel.

[0208] Therefore, by using inverted pilot pairs to perform pilot modulation on optical signals with different wavelength widths within the same channel, SRS crosstalk can be suppressed, the signal-to-noise ratio of low-frequency pilot signals can be improved, and the detection accuracy can be significantly enhanced.

[0209] Referring to scheme 5 in step 502, in some examples, pilot modulation can also be performed on multiple parts of the optical signal in a channel using pilot signals of different frequencies. Specifically, this scheme uses a pilot signal of a certain frequency to perform pilot modulation on multiple parts of the optical signal in a channel, and simultaneously uses inverted pilots to perform pilot modulation on each part of the optical signal in a channel, thus enabling the determination of SRS crosstalk.

[0210] based on Figure 7 The architecture shown is exemplary, referencing Figure 12 As shown in (1), the horizontal axis represents wavelength, and the vertical axis represents power. Specifically, the same channel (such as...) Figure 12 The optical signal in CH-1 in (1) is divided into two parts according to wavelength.

[0211] For example, WSS 101-1 can modulate a portion of the optical signal in the channel with a pilot signal of the same phase and frequency f1; and can modulate multiple wavelength widths of optical signals in another portion of the channel using an inverted pilot signal. For example, the first portion of the optical signal in CH-1 can be modulated using an inverted pilot signal of frequency f1; the first wavelength width of the optical signal in the second portion of CH-1 can be modulated using an inverted pilot signal of frequency f2; the first wavelength width of the optical signal in the second portion of CH-1 can be modulated using a normal pilot signal of frequency f2; the first wavelength width of the optical signal in the second portion of CH-1 can be modulated using a normal pilot signal of frequency f2; and the first wavelength width of the optical signal in the second portion of CH-1 can be modulated using an inverted pilot signal of frequency f2.

[0212] Combination Figure 7 The architecture shown is referenced. Figure 12 As shown in (2), the horizontal axis represents frequency and the vertical axis represents power. Specifically, the modulated multiplexed signal is received by a coupler (e.g., 103-1) and transmitted to a receiving device (e.g., receiving device 104-1).

[0213] In this section, since the optical signals of multiple wavelengths in another part of CH-1 are modulated separately using anti-phase pilot pairs, the modulated optical signals of multiple wavelengths are out of phase with each pair. Therefore, the SRS crosstalk of this part of the optical signal will be suppressed, i.e., canceled (see reference). Figure 11 The above).

[0214] Based on this, the power of the optical signal modulated by the frequency of the anti-phase pilot pair can be determined, i.e., the power corresponding to the signal modulated at frequency f2. The power of the optical signal modulated at frequency f2 is not affected by the SRS effect and there is no SRS crosstalk. The receiving device can determine the power of the optical signal modulated by the frequency of the anti-phase pilot signal, i.e., the power of the optical signal modulated at frequency f1. However, the power of the optical signal modulated at frequency f1 is still affected by the SRS effect and there is SRS crosstalk.

[0215] Thus, combined Figure 12 As shown in (2), Raman crosstalk can be determined by the difference between the power of the optical signal modulated at frequency f1 and the power of the optical signal modulated at frequency f2.

[0216] In some examples, modulation is achieved via WSS (e.g.) Figure 7 The architecture shown will introduce quantization errors into the pilot signal. Taking WSS 101-1 as an example, the quantization error generated during the modulation of multiple optical signals of different wavelengths by WSS 101-1 is as follows: quantization error refers to the error generated when quantizing analog signals.

[0217] Referring to step 602, the pilot-modulated optical signal can be detected at the same site where modulation is performed to obtain the intensity of the pilot-modulated optical signal, thereby determining the effect of pilot modulation at that site. The effect of pilot modulation includes whether the power of the pilot-modulated optical signal changes, and whether the signal-to-noise ratio of the pilot-modulated optical signal is low.

[0218] For example, refer to Figure 13 As shown, the effect of pilot modulation can be determined by a receiving device (e.g., receiving device 104-3) coupled at a common port of the same site (e.g., WSS 101-1) that performs pilot modulation on the optical signal.

[0219] Combination Figure 13 As shown, the receiving device 104-3 receives the optical signal modulated by the pilot signal of WSS 101-1. By detecting the optical signal modulated by the pilot signal of WSS-101, the effect of pilot modulation of the optical signal by WSS 101-1 can be determined. For example, the receiving device 104-3 detects the power of the optical signal to determine whether the power of the optical signal modulated by the pilot signal has changed, thus determining the effect of pilot modulation of the optical signal by WSS 101-1.

[0220] Therefore, by using the above method, the effect of pilot modulation of WSS can be determined in a timely manner, and the corresponding parameters of pilot modulation of WSS (such as the power of pilot signal) can be adjusted based on the quality of pilot modulation.

[0221] Furthermore, based on the determined pilot modulation effect, by continuously adjusting the corresponding parameters of the pilot modulation, the quantization error generated during WSS modulation can be reduced, thereby ensuring the detection accuracy of the optical channel performance.

[0222] Since the ability of WSS to modulate a triangular sine-shaped pilot signal is related to its own device performance, in order to ensure the effect of pilot modulation, other waveform pilot signals can also be used to perform pilot modulation on optical signals.

[0223] For example, refer to Figure 14 As shown in (1) and (2), the optical signals of two channels are illustrated, namely the first channel optical signal and the second channel optical signal. The horizontal axis represents time, and the vertical axis represents power.

[0224] Generally, the ability of a WSS to modulate a triangular sinusoidal pilot signal depends on the performance of devices such as the WSS (e.g., refresh rate). Based on this, in one possible implementation, if the effect of the modulated triangular sinusoidal pilot is poor (e.g., low signal-to-noise ratio), the WSS uses a square wave-shaped pilot signal to pilot modulate the optical signal.

[0225] based on Figure 7 The architecture shown, combined with Figure 14 As shown in (3), the first channel optical signal is pilot-modulated using a square-wave shaped pilot signal. Combined with... Figure 14 As shown in (4) in the figure, the second channel optical signal is pilot-modulated by a square wave-shaped pilot signal.

[0226] Based on this, combined Figure 14 As shown in (5), the modulated optical signals of the two channels can be used for code division multiplexing. That is, multiple signals can be transmitted simultaneously within the same frequency range.

[0227] Of course, the optical signal can also be modulated by pilot signals of other waveforms, and the embodiments of this application do not limit this.

[0228] Based on the above scheme, pilot modulation of optical signals can be achieved by using pilot signals of different waveforms.

[0229] In order to ensure that the service transmission of optical networks (such as DWDM systems) can be carried out normally and to facilitate flexible detection of the optical channel performance, it is necessary to erase and remodulate (i.e. write) the pilot signal in the link, that is, to erase and rewrite the pilot signal.

[0230] Referring to step 601, for example, WSS performs pilot modulation on the optical signal modulated by the pilot ...

[0231] based on Figure 7 The architecture shown is exemplary, referencing Figure 15 As shown, the link between the transmitter and receiver in a DWDM system typically includes one or more stations (e.g., WSS 101-3). Optionally, the station may also include a receiving device. For example, WSS 101-3 is also connected to receiving device 104-4.

[0232] Combination Figure 15 As shown, during pilot modulation erasure and write:

[0233] In the link, WSS 101-3 receives the pilot-modulated optical signal. The receiving device 104-4 can determine the frequency and phase of the pilot signal (e.g., identified as the first pilot signal) modulated by the pilot-modulated optical signal based on the frequency of the pilot-modulated optical signal. Furthermore, WSS 101-3 can erase the pilot signal by performing pilot modulation on the pilot-modulated optical signal using a pilot signal with the same frequency but opposite phase to the first pilot signal.

[0234] Furthermore, the WSS 101-3 can also re-pilot modulate the optical signal after erasing the pilot signal by using the first pilot signal determined by the receiving device 104-4.

[0235] Optionally, before performing pilot modulation on the erased multiplexed signal, WSS 101-3 first performs clock synchronization on the erased multiplexed signal to ensure that the remodulated multiplexed signal can be transmitted normally in the link.

[0236] Through the above scheme, the embodiments of this application can realize the erasure and remodulation of pilot modulation at any station in the link, thereby ensuring that the service transmission of the optical network (e.g., DWDM system) can be transmitted normally, and the detection location of the optical channel performance of the channel is more flexible.

[0237] In one possible implementation, overhead information also needs to be transmitted during the optical signal's service transmission.

[0238] Embodiments of this application can also erase pilot signals by using other devices or equipment to modulate the pilot signal. Generally, overhead information can be transmitted by pilot modulation of optical signals using low-frequency pilot signals. Furthermore, based on the above scheme, pilot signals can be erased in the link using WSS, for example, erasing low-frequency pilot signals modulated by optical signals for transmitting overhead information.

[0239] based on Figure 7 The architecture shown is exemplary, referencing Figure 16 As shown, the DWDM system also includes other devices or equipment with pilot modulation capabilities, such as... Figure 16 The modulation device in the system. Specifically, the modulation device can perform pilot modulation on different parts of the optical signal within the same channel using low-frequency pilot signals and high-frequency pilot signals. Furthermore, the WSS in the DWDM system link can recover the portion of the optical signal that has passed through the low-frequency pilot signal.

[0240] In one possible implementation, the modulation device is implemented by a modulator. Alternatively, the modulator can be implemented by an optical transport unit (OTU).

[0241] Combination Figure 16 The coordinate graph shows the modulation signal, where the horizontal axis represents wavelength and the vertical axis represents power. The modulation device in a DWDM system can perform pilot modulation on the optical signal of the same channel (labeled CH-1) using a mixed pilot signal and acquire the modulation signal. The mixed pilot signal includes a low-frequency pilot signal and a high-frequency pilot signal. Specifically, the low-frequency pilot signal (… Figure 16 The optical signal in CH-1 is pilot-modulated using a portion of the optical signal (marked as f1) to obtain the modulated signal; the high-frequency pilot signal ( Figure 16 The other part of the optical signal in CH-1 is pilot-modulated (marked as f2) to obtain the modulated signal.

[0242] Furthermore, combined Figure 15 As shown, the station in the link (i.e., WSS 101-3) can receive the optical signal modulated by the low-frequency pilot signal and erase the low-frequency pilot signal modulated by the optical signal. In this way, the optical signal can continue to be transmitted in the link, thereby ensuring that the service transmission can be carried out normally.

[0243] Through the above-described scheme, the embodiments of this application can modulate optical signals within the same channel using pilot signals of mixed frequencies, thereby transmitting overhead information through low-frequency pilot signals. Furthermore, the low-frequency pilot signals can be erased at any station in the link, thus ensuring the normal operation of service transmission in the DWDM system.

[0244] To determine the transmission performance of an optical network (such as a DWDM system), it is necessary to detect the power flatness of the optical signal transmitted by the system. Power flatness refers to the difference between the maximum and minimum power of the optical signal within a certain unit length (such as wavelength width, frequency width, etc.).

[0245] Referring to Scheme 6 in step 502, high-density pilot modulation can be performed on the optical signal of the same channel to detect the power flatness of the optical signal transmitted by the system. Here, high-density pilot modulation refers to dividing the optical signal into multiple parts with a small unit wavelength width and performing pilot modulation on each part.

[0246] based on Figure 7 The architecture shown is exemplary, referencing Figure 17 As shown in (1), high-density pilot modulation is performed on the optical signal of the same channel within a wavelength range of 0.8 nm. Here, the horizontal axis represents wavelength in nanometers (nm), and the vertical axis represents power. That is, the 0.8 nm wavelength range is subdivided according to smaller unit wavelength widths (such as...). Figure 17 The optical signal (0.05nm) is divided into multiple parts.

[0247] Combination Figure 17 As shown in (1), within the wavelength range of 0nm-0.2nm: the optical signal in the wavelength range of 0nm-0.05nm is pilot-modulated by the anti-phase pilot signal of frequency f1, the optical signal in the wavelength range of 0.05nm-0.1nm is pilot-modulated by the anti-phase pilot signal of frequency f2, the optical signal in the wavelength range of 0.1nm-0.15nm is pilot-modulated by the anti-phase pilot signal of frequency f3, and the optical signal in the wavelength range of 0.15nm-0.2nm is pilot-modulated by the anti-phase pilot signal of frequency f4.

[0248] Within the wavelength range of 0.2nm-0.4nm: the optical signal in the wavelength range of 0.2nm-0.25nm is pilot-modulated using a positive-phase pilot signal of frequency f1; the optical signal in the wavelength range of 0.25nm-0.3nm is pilot-modulated using a positive-phase pilot signal of frequency f2; the optical signal in the wavelength range of 0.3nm-0.35nm is pilot-modulated using a positive-phase pilot signal of frequency f3; and the optical signal in the wavelength range of 0.35nm-0.4nm is pilot-modulated using a positive-phase pilot signal of frequency f4.

[0249] Within the wavelength range of 0.4nm-0.6nm: the optical signal in the wavelength range of 0.4nm-0.45nm is pilot-modulated using a positive-phase pilot signal at frequency f4; the optical signal in the wavelength range of 0.45nm-0.5nm is pilot-modulated using a positive-phase pilot signal at frequency f3; the optical signal in the wavelength range of 0.5nm-0.55nm is pilot-modulated using a positive-phase pilot signal at frequency f2; and the optical signal in the wavelength range of 0.55nm-0.6nm is pilot-modulated using a positive-phase pilot signal at frequency f1.

[0250] Within the wavelength range of 0.4nm-0.6nm: the optical signal in the wavelength range of 0.6nm-0.65nm is pilot-modulated using an inverted pilot signal at frequency f4; the optical signal in the wavelength range of 0.65nm-0.7nm is pilot-modulated using an inverted pilot signal at frequency f3; the optical signal in the wavelength range of 0.7nm-0.75nm is pilot-modulated using an inverted pilot signal at frequency f2; and the optical signal in the wavelength range of 0.75nm-0.8nm is pilot-modulated using an inverted pilot signal at frequency f1.

[0251] In CH-1, the pilot signals modulated by corresponding optical signals within two unit wavelength ranges form an anti-phase pilot pair. For example, the anti-pilot signal modulated by an optical signal within the 0nm-0.05nm wavelength range and the positive pilot signal modulated by an optical signal within the 0.2nm-0.25nm wavelength range form an anti-phase pilot pair. This avoids SRS crosstalk.

[0252] Combination Figure 17 As shown in (2), when filtering a pilot-modulated optical signal with a wavelength range of 0.8 nm, only multiple single-phase signals (including positive-phase or negative-phase signals) can be filtered out. The horizontal axis represents wavelength in nanometers (nm), and the vertical axis represents power. For example... Figure 17 As shown in (2) in the figure, multiple inverted signals are filtered out.

[0253] In conjunction with the above embodiments, the power of optical signals modulated by different wavelength ranges of the positive phase signal of the positive phase pilot signal after transmission in the same channel is the same as the power of optical signals modulated by different wavelength ranges of the anti-phase pilot signal in the same channel after transmission. Therefore, by measuring the power of optical signals in different wavelength ranges of the anti-phase signal, the power of optical signals in different wavelength ranges of the positive phase signal can be determined, thereby determining the power of the optical signals transmitted throughout the entire channel.

[0254] Therefore, based on the filtered out inverted signals of multiple unit wavelength widths, the power of the inverted signals of multiple unit wavelength widths can be determined, thereby determining the power of the optical signals transmitted within multiple unit wavelength widths in the channel. This allows for the determination of the power flatness of the optical signals transmitted in the channel.

[0255] In one possible implementation, embodiments of this application provide a transmission apparatus. This transmission apparatus is used to perform the signal transmission method as described in the above embodiments of this application. For example, the transmission apparatus can be used to perform... Figure 5 and Figure 6 The aforementioned signal transmission method.

[0256] In one possible implementation, an embodiment of this application provides an optical network. The optical network includes: multiple optical transmitters, multiple optical receivers, and at least one transmission device as described in the above embodiments of this application; wherein the transmission device includes a common port and multiple branch ports; the branch ports are used to connect to the optical transmitters, and the common port is used to connect to the multiple optical receivers via optical fibers.

[0257] Optionally, the optical network includes a wavelength division multiplexing (DWDM) system. Exemplary examples of the DWDM system's architecture can be found in... Figure 7 , Figure 13 or Figure 16 The DWDM system shown.

[0258] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software programs, it can be implemented, in whole or in part, in the form of a computer program product. This computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that can be integrated with one or more media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)). In embodiments of this application, the computer may include the aforementioned apparatus.

[0259] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0260] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of this application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from the spirit and scope of this application. Thus, if such modifications and modifications of this application fall within the scope of the claims of this application and their equivalents, this application is also intended to include such modifications and modifications.

Claims

1. A signal transmission method, characterized in that, The signal transmission method is applied to a first transmission device in an optical network. The first transmission device includes a wavelength selective switch (WSS) module. The WSS module includes multiple branch ports and a common port. The branch ports are used to connect to an optical transmitter, and the common port is used to connect to an optical fiber. The signal transmission method includes: Acquire a first optical signal received by a first branch port among the plurality of branch ports, and acquire a second optical signal received by a second branch port among the plurality of branch ports; wherein the wavelengths of the first optical signal and the second optical signal are different; The first optical signal is pilot-modulated in the time domain to obtain the first modulation signal; The second optical signal is pilot-modulated in the time domain to obtain the second modulation signal; The first modulation signal and the second modulation signal are transmitted to the optical fiber through the common port.

2. The signal transmission method according to claim 1, characterized in that, The signal transmission method further includes: Acquire the third optical signal received by the third branch port among the plurality of branch ports, wherein the wavelengths of the first optical signal, the second optical signal and the third optical signal are different from each other; The third optical signal is pilot-modulated in the time domain to obtain the third modulation signal; The third modulation signal is transmitted to the optical fiber through the common port.

3. The signal transmission method according to claim 1 or 2, characterized in that, The step of pilot modulation of the first optical signal in the time domain includes: In the time domain, the first optical signal is intensity modulated; The step of pilot modulation of the second optical signal in the time domain includes: In the time domain, the second optical signal is intensity modulated.

4. The signal transmission method according to any one of claims 1-3, characterized in that, The step of pilot modulation of the first optical signal in the time domain includes: In the time domain, the first optical signal is intensity modulated by the first pilot signal; The step of pilot modulation of the second optical signal in the time domain includes: In the time domain, the second optical signal is intensity modulated by the second pilot signal; The first pilot signal and the second pilot signal have different frequencies.

5. The signal transmission method according to any one of claims 1-3, characterized in that, The step of performing pilot modulation on the first optical signal in the time domain to obtain the first modulation signal includes: In the time domain, the first part of the optical signal in the first optical signal is pilot-modulated by the third pilot signal to obtain the first part of the modulated signal of the first optical signal. In the time domain, the second part of the optical signal in the first optical signal is pilot-modulated by the fourth pilot signal to obtain the second part of the modulated signal of the first optical signal. Based on the first portion of the modulation signal and the second portion of the modulation signal, the first modulation signal is obtained; The phase of the third pilot signal differs from that of the fourth pilot signal by 180 degrees, and the third pilot signal and the fourth pilot signal have the same frequency.

6. The signal transmission method according to any one of claims 1-3, characterized in that, The step of performing pilot modulation on the first optical signal in the time domain to obtain the first modulation signal includes: In the time domain, the first part of the optical signal in the first optical signal is pilot-modulated by the fifth pilot signal to obtain the third part of the modulated signal of the first optical signal; In the time domain, the second part of the optical signal in the first optical signal is pilot-modulated by the sixth pilot signal to obtain the fourth part of the modulated signal of the first optical signal; Based on the third part of the modulation signal and the fourth part of the modulation signal, the first modulation signal is obtained; The fifth pilot signal has a different frequency than the sixth pilot signal.

7. The signal transmission method according to any one of claims 1-3, characterized in that, The step of performing pilot modulation on the first optical signal in the time domain to obtain the first modulation signal includes: In the time domain, the first part of the first optical signal is pilot-modulated using the seventh pilot signal to obtain the seventh part of the modulation signal of the first optical signal; In the time domain, the second part of the optical signal in the first optical signal is pilot-modulated by the eighth pilot signal to obtain the eighth part of the modulated signal of the first optical signal; In the time domain, the third part of the optical signal in the first optical signal is pilot-modulated by the ninth pilot signal to obtain the ninth part of the modulation signal of the first optical signal; Based on the seventh, eighth, and ninth modulated signals, the first modulated signal is obtained; Wherein, the wavelengths of the first portion of the optical signal are all shorter than the wavelengths of the second portion of the optical signal, and the wavelengths of the second portion of the optical signal are all shorter than the wavelengths of the third portion of the optical signal; or, the wavelengths of the second portion of the optical signal are all shorter than the wavelengths of the third portion of the optical signal; and the wavelengths of the first portion of the optical signal are all longer than the wavelengths of the third portion of the optical signal. The seventh pilot signal and the eighth pilot signal are 180 degrees out of phase, and the seventh pilot signal and the eighth pilot signal have the same frequency; The seventh pilot signal has a different frequency than the ninth pilot signal.

8. The signal transmission method according to any one of claims 1-3, characterized in that, The step of performing pilot modulation on the first optical signal in the time domain to obtain the first modulation signal includes: In the time domain, the first to eighth parts of the first optical signal are sequentially pilot-modulated using the tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, sixteenth, and seventeenth pilot signals to obtain the first modulated signal. The wavelengths of the first part of the optical signal to the eighth part of the optical signal are distributed in ascending order; The tenth pilot signal, the twelfth pilot signal, the fifteenth pilot signal, and the seventeenth pilot signal have a first frequency, and the eleventh pilot signal, the thirteenth pilot signal, the fourteenth pilot signal, and the sixteenth pilot signal have a second frequency; the first frequency and the second frequency are different. The tenth pilot signal, the eleventh pilot signal, the sixteenth pilot signal, and the seventeenth pilot signal have the same phase, and the twelfth pilot signal, the thirteenth pilot signal, the fourteenth pilot signal, and the fifteenth pilot signal have the same phase. The eleventh pilot signal is 180 degrees out of phase with the twelfth pilot signal.

9. A signal transmission method, characterized in that, A second transmission device for use in an optical network; the second transmission device includes a WSS module; the WSS module includes multiple branch ports and a common port, the common port of the second transmission device being used to connect an optical fiber; The signal transmission method includes: Acquire the first modulation signal and the second modulation signal received at the common port; wherein the first modulation signal and the second modulation signal have different wavelengths; The intensity of the first modulation signal and the intensity of the second modulation signal are obtained; wherein the intensity is used to indicate the light intensity of the modulation signal.

10. The signal transmission method according to claim 9, characterized in that, The signal transmission method further includes: Obtain the third modulation signal received at the common port; wherein the first modulation signal, the second modulation signal, and the third modulation signal have different wavelengths; Obtain the strength of the third modulation signal.

11. The signal transmission method according to claim 9, characterized in that, The step of obtaining the intensity of the first modulated signal includes: The first modulation signal is photoelectrically converted to obtain a first electrical signal; Based on the first electrical signal, obtain the first digital signal; The intensity of the first modulated signal is obtained based on the first digital signal.

12. The signal transmission method according to claim 9, characterized in that, The step of obtaining the intensity of the second modulated signal includes: The second modulation signal is photoelectrically converted to obtain a second electrical signal; Based on the second electrical signal, obtain the second digital signal; The intensity of the second modulated signal is obtained based on the second digital signal.

13. The signal transmission method according to claim 9, characterized in that, The signal transmission method further includes: In the time domain, the first modulation signal is pilot-modulated using the seventh pilot signal to obtain the first optical signal; The seventh pilot signal is 180 degrees out of phase with the first pilot signal, and the seventh pilot signal has the same frequency as the first pilot signal.

14. The signal transmission method according to claim 9, characterized in that, The signal transmission method further includes: In the time domain, the second modulation signal is pilot-modulated using the eighth pilot signal to obtain the second optical signal; The eighth pilot signal is 180 degrees out of phase with the second pilot signal, and the eighth pilot signal has the same frequency as the second pilot signal.

15. A transmission device, characterized in that, The transmission device is used to perform the signal transmission method as described in any one of claims 1-14.

16. An optical network, characterized in that, The optical network includes: multiple optical transmitters, multiple optical receivers, and at least one transmission device as described in claim 15; The transmission device includes a common port and multiple branch ports; The branch port is used to connect to the optical transmitter, and the common port is used to connect to the plurality of optical receivers via optical fiber.

17. The optical network according to claim 16, characterized in that, The optical network includes a dense wavelength division multiplexing (DWDM) system.

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