Frequency offset detection method and device

Abstract

The invention provides a frequency deviation detection method. The method comprises the following steps: inputting a first detection optical signal and a second detection optical signal with different frequencies to a target optical channel through a detection light source; the target optical channel is an idle optical channel passing through the target optical band-pass device; acquiring a first input optical power of the first detection optical signal and a second input optical power of the second detection optical signal at the input detection point, and acquiring a first output optical power of the first detection optical signal and a second output optical power of the second detection optical signal at the output detection point; wherein in the target optical channel, the input detection point is located between the detection light source and the target optical band-pass device, and the output detection point is located behind the target optical band-pass device; and determining the frequency deviation of the target optical band-pass device according to the first input optical power, the first output optical power, the second input optical power and the second output optical power. The invention further provides a frequency deviation detection device.

Description

Technical Field

[0001] The present disclosure relates to the technical field of frequency offset detection, and particularly to a method and a device for frequency offset detection. Background Art

[0002] In an optical transport network (OTN, Optical Transport Network), there may be a difference between the transmission spectrum of an optical bandpass device and the desired spectrum, that is, there is a frequency offset (frequency deviation).

[0003] In the related art, the frequency offset condition of an idle optical channel cannot be effectively detected, so switching to a faulty idle optical channel may seriously affect the network quality. Summary of the Invention

[0004] The present disclosure provides a method and a device for frequency offset detection.

[0005] In a first aspect, an embodiment of the present disclosure provides a method for frequency offset detection, which includes:

[0006] Detecting a first detection optical signal and a second detection optical signal with different frequencies input by a detection light source to a target optical channel; the target optical channel is an idle optical channel passing through a target optical bandpass device;

[0007] Obtaining a first input optical power of the first detection optical signal and a second input optical power of the second detection optical signal at an input detection point, and obtaining a first output optical power of the first detection optical signal and a second output optical power of the second detection optical signal at an output detection point; wherein, in the target optical channel, the input detection point is located between the detection light source and the target optical bandpass device, and the output detection point is located after the target optical bandpass device;

[0008] Determining the frequency offset of the target optical bandpass device according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power.

[0009] In a second aspect, an embodiment of the present disclosure provides a device for frequency offset detection, which includes:

[0010] A detection light source, which is used to connect to a target optical channel and input a first detection optical signal and a second detection optical signal with different frequencies to the target optical channel; the target optical channel is an idle optical channel passing through a target optical bandpass device;

[0011] A detection module, configured to: obtain a first input optical power of the first detection optical signal and a second input optical power of the second detection optical signal at an input detection point, and obtain a first output optical power of the first detection optical signal and a second output optical power of the second detection optical signal at an output detection point; wherein, in the target optical channel, the input detection point is located between the detection light source and the target optical bandpass device, and the output detection point is located after the target optical bandpass device; and determine a frequency offset of the target optical bandpass device according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power.

[0012] In the embodiments of the present disclosure, a detection optical signal is input into an idle optical channel through a detection light source, and a frequency offset is calculated according to the optical power condition of the detection optical signal. Thus, the embodiments of the present disclosure can realize the detection of the frequency offset of the idle optical channel, improve the network quality according to the detection result, and the detection method is simple and accurate. Description of the Drawings

[0013] In the drawings of the embodiments of the present disclosure:

[0014] Figure 1 is a flowchart of a method for detecting frequency offset provided by an embodiment of the present disclosure;

[0015] Figure 2 is a flowchart of another method for detecting frequency offset provided by an embodiment of the present disclosure;

[0016] Figure 3 is a block diagram of the composition of a device for detecting frequency offset provided by an embodiment of the present disclosure;

[0017] Figure 4 is a block diagram of the composition of an OTN applicable to a method for detecting frequency offset provided by an embodiment of the present disclosure;

[0018] Figure 5 is a schematic diagram of the correspondence between the optical power difference and the frequency offset in another method for detecting frequency offset provided by an embodiment of the present disclosure;

[0019] Figure 6 is a block diagram of the composition of a detection light source in a method for detecting frequency offset provided by an embodiment of the present disclosure;

[0020] Figure 7 is a block diagram of the composition of an OTN applicable to another method for detecting frequency offset provided by an embodiment of the present disclosure;

[0021] Figure 8 is a block diagram of the composition of an OTN applicable to another method for detecting frequency offset provided by an embodiment of the present disclosure. Detailed Description of the Embodiments

[0022] To enable those skilled in the art to better understand the technical solutions of the present disclosure, the methods and apparatuses for frequency offset detection provided in the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0023] The present disclosure will be described more fully hereinafter with reference to the accompanying drawings. However, the illustrated embodiments may be embodied in different forms and the present disclosure should not be construed as limited to the embodiments set forth below. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0024] The accompanying drawings of the embodiments of the present disclosure are used to provide a further understanding of the embodiments of the present disclosure, and constitute a part of the specification, and are used to explain the present disclosure together with the detailed embodiments, and do not constitute a limitation to the present disclosure. By describing the detailed embodiments with reference to the accompanying drawings, the above and other features and advantages will become more apparent to those skilled in the art.

[0025] The present disclosure may be described with reference to the plan view and / or cross-sectional view by means of the ideal schematic diagrams of the present disclosure. Therefore, the example illustrations can be modified according to the manufacturing technology and / or tolerances.

[0026] Without conflict, the embodiments of the present disclosure and the features in the embodiments may be combined with each other.

[0027] The terms used in the present disclosure are only for describing specific embodiments and are not intended to limit the present disclosure. As used in the present disclosure, the term "and / or" includes any and all combinations of one or more of the related listed items. As used in the present disclosure, the singular forms "a" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. As used in the present disclosure, the terms "comprising", "made of", specify the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their groups.

[0028] Unless otherwise defined, the meanings of all terms (including technical and scientific terms) used in the present disclosure are the same as those commonly understood by those of ordinary skill in the art. It will also be understood that terms such as those defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted as having an idealized or overly formal meaning unless the present disclosure clearly so defines.

[0029] The present disclosure is not limited to the embodiments shown in the accompanying drawings, but includes modifications to the configurations formed based on the manufacturing process. Therefore, the regions illustrated in the accompanying drawings have schematic properties, and the shapes of the regions shown in the drawings illustrate the specific shapes of the regions of the elements, but are not intended to be restrictive.

[0030] The optical transport network (OTN) is a high-capacity and high-speed communication network that facilitates the transmission of optical signals over optical fibers.

[0031] One of the important basic technologies of OTN is wavelength division multiplexing (WDM) technology, that is, specific frequency range components are separated from the input optical signal through an optical bandpass filter (OBPF) and allowed to pass through (i.e., "bandpass").

[0032] Among them, the specific form of the optical bandpass device is diverse, such as a wavelength selective switch (WSS), an arrayed waveguide grating (AWG), etc. For example, in an OTN based on a reconfigurable optical add / drop multiplexer (ROADM) and an optical cross-connect (OXC), the WSS can independently switch the optical signal of each frequency (wavelength), dynamically adjust the wavelengths of the add / drop services, and improve the quality and efficiency of information transmission.

[0033] However, due to the influence of factors such as temperature, aging, and process, the performance of the optical bandpass device will change, resulting in its transmission spectrum being different from the expected spectrum, that is, there is a "frequency offset".

[0034] This frequency offset will cause misalignment of the transmitted spectrum and spectral damage, affect the protection frequency between channels, deteriorate the transmission quality of optical signals, increase the bit error rate, and ultimately affect the network quality. Therefore, it is necessary to detect the frequency offset of the optical bandpass device to alleviate the filtering cost, especially in an OTN with a high baud rate modulation format, this is even more important.

[0035] In some related technologies, when the OTN is working, the frequency offset can be detected through the bit error rate of the optical channel, service data signals, overhead optical labels, etc.

[0036] However, the above detection is based on the actual transmission of service signals in the optical channel; while OTN may have some idle optical channels that do not transmit service signals when working. There is no service signal in these idle optical channels, so it is impossible to determine their frequency offset, etc., and the faults in them cannot be discovered in time. In some cases (such as service failure), the idle optical channels will be switched to the use state and start to transmit service signals. When switching to the above idle optical channels with faults, not only can the problem not be solved (such as the service cannot be restored), but it will seriously affect the network quality.

[0037] In a first aspect, an embodiment of the present disclosure provides a method for frequency offset detection.

[0038] The disclosed embodiments are used to detect the frequency offset of an optical bandpass device (such as WSS, AWG, etc.) through which an optical channel in an OTN passes, and specifically to detect the frequency offset of an idle optical channel through the optical bandpass device when the OTN is working (transmitting service signals).

[0039] It should be understood that the specific application modes of the embodiments of the present disclosure are various, such as:

[0040] (1) When the OTN is operating normally, the optical bandpass devices of the idle optical channels are detected using the embodiments of the present disclosure to determine the performance of each optical bandpass device, thereby determining which idle optical channels can be used as switching targets.

[0041] (2) The performance of each optical bandpass device in the OTN is detected by using the embodiments of the present disclosure through regular inspections, etc., so as to perform advance maintenance, optimize network configuration, etc., and improve network quality.

[0042] (3) When it is found that the network performance of OTN is poor, such as when the optical signal-to-noise ratio (OSNR) is low, each optical channel is taken as an idle optical channel in turn, and detection is performed through the embodiments of the present disclosure to find or eliminate the faults of each optical bandpass device, thereby achieving more accurate fault location.

[0043] The structure of the OTN to which the embodiments of the present disclosure apply can be referred to Figure 4 , which includes multiple optical channels. In each site, each optical channel will pass through the corresponding optical bandpass device (or the corresponding port of the optical bandpass device). The optical channel to be detected (target optical channel) must be idle (not carrying any business), and there are some other optical channels in operation (carrying business) in the OTN, that is, the OTN as a whole should be in working state, and the idle optical channel is relative to other working optical channels.

[0044] Reference Figure 1 , the method of the embodiment of the present disclosure includes:

[0045] S101. Input a first detection optical signal and a second detection optical signal with different frequencies into a target optical channel through a detection light source.

[0046] Wherein, the target optical channel is an idle optical channel passing through a target optical bandpass device.

[0047] S102. Obtain a first input optical power of the first detection optical signal and a second input optical power of the second detection optical signal at an input detection point, and obtain a first output optical power of the first detection optical signal and a second output optical power of the second detection optical signal at an output detection point.

[0048] Wherein, in the target optical channel, the input detection point is located between the detection light source and the target optical bandpass device, and the output detection point is located after the target optical bandpass device.

[0049] S103. Determine the frequency offset of the target optical bandpass device according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power.

[0050] In the embodiments of the present disclosure, when OTN is operating, a detection optical signal is input into a target optical channel without a service signal through an external detection light source. The target optical channel passes through a target optical bandpass device to be detected (specifically, it can be a port to be detected passing through the target optical bandpass device). Thus, the detection optical signal will be input into the target optical bandpass device and output after being filtered by the target optical bandpass device. The detection optical signal is specifically a first detection optical signal and a second detection optical signal, and the frequencies (wavelengths) of the first detection optical signal and the second detection optical signal are different.

[0051] Therefore, at a position (input detection point) in the target optical channel before entering the target optical bandpass device, the optical power (first input optical power, second input optical power) of the detection optical signal that has not passed through the target optical bandpass device at this position can be obtained. It can be to detect the optical power with an optical power detection module such as a photodetector at the input detection point, or to obtain the optical power at a specific position in itself through the device at the input detection point (for example, the target optical bandpass device itself can obtain the optical power of the input optical signal).

[0052] And at a position (output detection point) in the target optical channel after the target optical bandpass device, the optical power (first output optical power, second output optical power) of the detection optical signal that has passed through the target optical bandpass device at this position can be obtained. It can be to detect the optical power with an optical power detection module such as a photodetector at the output detection point, or to obtain the optical power at a specific position in itself through the device at the output detection point (for example, the target optical bandpass device itself can obtain the optical power of the output optical signal).

[0053] Based on the first input optical power, the second input optical power, the first input optical power, and the second input optical power obtained above, the frequency offset of the target optical bandpass device (specifically, a specific port of the target optical bandpass device) can be calculated.

[0054] It should be understood that if there are multiple optical bandpass devices between the input detection point and the output detection point, they all belong to the target optical bandpass device. That is, the detected frequency offset is the overall result of these target optical bandpass devices.

[0055] Further, when the detection result shows a frequency offset, the input detection point and / or the output detection point can be reselected, and the frequency offset of all target optical bandpass devices between the newly selected input detection point and the output detection point can be detected again, so as to achieve accurate positioning of the frequency offset.

[0056] For example, if there are two target optical bandpass devices, device X1 and device X2, between the input detection point and the output detection point, and a frequency offset is detected; then the output detection point located between the output target optical bandpass device X1 and the target optical bandpass device X2 can be reselected, so that this detection only targets the target optical bandpass device X1. If the detection result shows no frequency offset, it can be determined that in fact, the target optical bandpass device X2 has a frequency offset.

[0057] In the embodiments of the present disclosure, a detection optical signal is input from a light source to an idle optical channel, and the frequency offset is calculated based on the optical power situation of the detection optical signal. Thus, the embodiments of the present disclosure can detect the frequency offset of the idle optical channel, improve the network quality according to the detection result, and its detection method is simple and accurate.

[0058] In some embodiments, referring to Figure 2 , determining the frequency offset of the target optical bandpass device (S103) according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power includes:

[0059] S1031. Determine the optical power difference according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power.

[0060] Wherein, the optical power difference is the difference between the first optical power loss and the second optical power loss. The first optical power loss is the difference between the first input optical power and the first output optical power, and the second optical power loss is the difference between the second input optical power and the second output optical power.

[0061] S1032. Determine the frequency offset of the target optical bandpass device according to the optical power difference.

[0062] As a way of the embodiments of the present disclosure, the optical power of the detection optical signal obtained above can be further used to calculate the "optical power difference".

[0063] Among them, the optical power difference △P is the difference between the first optical power loss △P1 and the second optical power loss △P2, that is:

[0064] △P = △P1 - △P2.

[0065] Among them, due to the need for filtering, etc., the optical power △P1A of the first detected optical signal when input to the target optical band-pass device ( Figure 4 the optical power at point A in Figure 4 ), is usually not equal to the optical power △P1B when output from the target optical band-pass device (

[0066] the optical power at point A in

[0067] ), but there is a certain gap, which is the first optical power loss △P1, that is:

[0068] △P1 = PA1 - PB1;

[0069] Similarly, the second detected optical signal also has a corresponding second optical power loss △P2, that is:

[0070] △P2 = PA2 - PB2;

[0071] It should be understood that although △P conforms to the above formula, it does not mean that the specific values of PA1, PB1, PA2, and PB2 must be detected separately and then △P is calculated according to the above formula. It can also be obtained through any other mathematically equivalent detection and algorithm.

[0072] Among them, the relationship between the above two optical power losses (△P1, △P2) is determined by the frequency offset of the target optical band-pass device, that is, there is a corresponding relationship between △P and the frequency offset. For example, it is a reference to Figure 5 the corresponding relationship.

[0073] Thus, after determining △P, the frequency offset of the target optical band-pass device can be determined according to the preset corresponding relationship, and the detection of the frequency offset is completed.

[0074] Among them, the above method can obtain the optical power difference through simple operations such as addition and subtraction, and the optical power difference accurately corresponds to the frequency offset, so it is both simple and accurate.

[0075] In some embodiments, the first detected optical signal is a narrow-band light, the second detected optical signal is a narrow-band light, and the narrow-band light of the first detected optical signal and the narrow-band light of the second detected optical signal are symmetrically distributed with respect to the center frequency of the target optical channel.

[0076] As a way of an embodiment of the present disclosure, both the first detection optical signal and the second detection optical signal emitted by the detection light source can be narrowband light, and the two narrowband lights are symmetric with respect to the center frequency of the target optical channel, that is, the widths of the two narrowband lights are the same, and the distances from the center frequency are the same. That is to say, the first detection optical signal and the second detection optical signal form a pair of narrowband lights (left and right narrowband lights) within a service channel.

[0077] Among them, when there is no frequency offset in the optical bandpass device, for the left and right narrowband lights, the change in the filtered optical power (optical power loss) should be equal, that is:

[0078] △P1 = △P2;

[0079] If there is a frequency offset, the filtering degrees of the optical bandpass device for the left and right narrowband lights are different, that is, the changes in the filtered optical power (optical power losses) are not equal, that is, △P1 is not equal to △P2. Moreover, the degree of frequency offset determines the relative magnitudes of △P1 and △P2 and the specific value of the difference between the two.

[0080] Thus, referring to Figure 5 , when △P = 0, it can be determined that the target optical bandpass device has no frequency offset (or the frequency offset is 0); and if △P is not 0, then the direction and magnitude of the frequency offset of the target optical bandpass device can be determined according to its positive or negative value and specific value.

[0081] In some embodiments, the detection light source includes: a doped optical amplification module and an optical filter module connected to the output end of the doped optical amplification module; inputting the first detection optical signal and the second detection optical signal with different frequencies into the target optical channel through the detection light source (S101), including:

[0082] S1011. Output a broadband optical signal to the optical filter module through the spontaneous emission of the doped optical amplification module.

[0083] S1012. Perform a first filtering operation on the broadband optical signal through the optical filter module to obtain the first detection optical signal, and input the first detection optical signal into the target optical channel, and perform a second filtering operation on the broadband optical signal through the optical filter module to obtain the second detection optical signal, and input the second detection optical signal into the target optical channel.

[0084] In some embodiments, the doped optical amplification module includes: a doped fiber amplifier; or, a plurality of cascaded doped fiber amplifiers.

[0085] Referring to Figure 6, the detection light source can specifically be composed of a doped optical amplification module and an optical filter module; among them, the doped optical amplification module includes a doped fiber amplifier (DFA, Doped Fiber Amplifier), such as an erbium-doped fiber amplifier (EDFA, Erbium Doped Fiber Amplifier); the output end of the doped optical amplification module is connected to an optical filter module (such as WSS, AWG, etc.) that can perform filtering of the required frequency, and the output end of the optical filter module serves as the output end of the overall detection light source.

[0086] Among them, the doped optical amplification module can have only one doped fiber amplifier; it can also be multiple cascaded doped fiber amplifiers (that is, the output of the previous-stage doped fiber amplifier is connected to the input of the next-stage doped fiber amplifier), so as to improve the output efficiency.

[0087] Refer to Figure 6 , since the doped optical amplification module is a "doped" optical amplifier (OA, Optical Amplifier), it can continuously and automatically generate optical signals through spontaneous emission, and the optical signals are broadband optical signals within a relatively large frequency range, and the broadband optical signals are then output to the optical filter module; and then refer to Figure 6 , the optical filter module can perform filtering operations (the first filtering operation, the second filtering operation) on the broadband optical signals respectively to generate two optical signals with different frequencies (such as the above left and right narrowband lights), and when these two optical signals are input into the target optical channel, they are the first detection optical signal and the second detection optical signal.

[0088] Thus, the devices used in the detection light source of the embodiments of the present disclosure are all common devices in OTN such as OA and WSS, and there is no need to externally add a "laser (such as a tunable laser)", nor other devices such as a coupler; therefore, the structure of the detection light source is simple and easy to implement.

[0089] In some embodiments, inputting the first detection optical signal and the second detection optical signal with different frequencies into the target optical channel by the detection light source, (S101) includes:

[0090] S101A. Input the first detection optical signal and the second detection optical signal into the target optical channel simultaneously by the detection light source.

[0091] As a way of the embodiments of the present disclosure, the detection light source can "simultaneously" output two detection optical signals with different frequencies.

[0092] In some embodiments, obtaining the first input optical power of the first detection optical signal and the second input optical power of the second detection optical signal at the input detection point, and obtaining the first output optical power of the first detection optical signal and the second output optical power of the second detection optical signal at the output detection point includes (S102), including:

[0093] S102A1. Obtain the input optical power distribution spectrum at the input detection point and obtain the output optical power distribution spectrum at the output detection point.

[0094] S102A2. Determine the first input optical power and the second input optical power according to the input optical power distribution spectrum, and determine the first output optical power and the second output optical power according to the output optical power distribution spectrum.

[0095] As a way of the embodiments of the present disclosure, when the detection light source inputs the first detection optical signal and the second detection optical signal simultaneously, the optical signal in the target optical channel actually includes the components of the first detection optical signal and the second detection optical signal at the same time.

[0096] Thus, the input optical power distribution spectrum (i.e., the optical power value of the optical signal at each frequency) of the optical signal input to the target optical bandpass device can be obtained at the input detection point (such as point A in Figure 4 ); and the output optical power distribution spectrum of the optical signal output from the target optical bandpass device can be obtained at the output detection point (such as point B in Figure 4 ).

[0097] Furthermore, according to the input optical power distribution spectrum, the "partial optical power" corresponding to the frequency of the first detection optical signal can be separated therefrom as the first input optical power PA1, and the optical power of the corresponding part of the frequency of the second detection optical signal can be separated as the second input optical power PA2. Correspondingly, the first output optical power PB1 and the second output optical power PB2 can also be separated through the output optical power distribution spectrum.

[0098] Furthermore, the above △P can be calculated according to PA1, PA2, PB1, and PB2.

[0099] In some embodiments, referring to Figure 2 , input the first detection optical signal and the second detection optical signal (S101) with different frequencies into the target optical channel through the detection light source, including:

[0100] S101B. Through the detection light source, input the first detection optical signal and the second detection optical signal into the target optical channel at different times respectively.

[0101] As another way of the embodiments of the present disclosure, referring to Figure 2 , the detection light source can also input the first detection optical signal and the second detection optical signal into the target optical bandpass device at different times respectively.

[0102] In some embodiments, obtaining a first input optical power of a first detection optical signal and a second input optical power of a second detection optical signal at an input detection point, and obtaining a first output optical power of the first detection optical signal and a second output optical power of the second detection optical signal at an output detection point (S102) includes:

[0103] S102BA1. When the first detection optical signal is input to the target optical channel, obtain the first input optical power at the input detection point and obtain the first output optical power at the output detection point.

[0104] S102BA2. When the second detection optical signal is input to the target optical channel, obtain the second input optical power at the input detection point and obtain the second output optical power at the output detection point.

[0105] It should be understood that the description and numbering order of the above steps S102BA1 and S102BA2 do not represent their necessary execution order.

[0106] As another way of the embodiments of the present disclosure, when the first detection optical signal and the second detection optical signal are respectively input, the optical powers of the optical signals can be respectively obtained at the input detection point and the output detection point when the first detection optical signal is input, that is, the first input optical power PA1 and the first output optical power PB1; and the second input optical power PA2 and the second output optical power PB2 are respectively obtained at the input detection point and the output detection point when the second detection optical signal is input.

[0107] Furthermore, the above △P can be calculated based on PA1, PA2, PB1, and PB2.

[0108] In some embodiments, referring to Figure 2 , when multiple optical channels including the target optical channel pass through the input detection point and the optical channels passing through the output detection point are the same as those passing through the input detection point;

[0109] S102BB1. When the first detection optical signal is input to the target optical channel, obtain the first total input optical power at the input detection point and obtain the first total output optical power at the output detection point.

[0110] Among them, the first total input optical power includes a fixed-value input optical power and the first input optical power, and the first total output optical power includes a fixed-value output optical power and the first output optical power.

[0111] S102BB2. When the second detection optical signal is input to the target optical channel, obtain the second total input optical power at the input detection point and obtain the second total output optical power at the output detection point.

[0112] Among them, the second input total optical power includes a fixed input optical power and a second input optical power, and the second output total optical power includes a fixed output optical power and a second output optical power.

[0113] It should be understood that the description and numbering order of the above steps S102BB1 and S102BB2 do not represent their necessary execution order.

[0114] As a way of the embodiments of the present disclosure, the input detection point and the output detection point may not be separately located on the "target optical channel", but on the "total channel" of multiple optical channels, for example, located in front of the demultiplexing port and behind the multiplexing port respectively.

[0115] Thus, when the first detection optical signal and the second detection optical signal are respectively input, the optical power obtained at the input detection point is not the first input optical power and the second input optical power, but the sum of the optical powers of multiple optical channels, that is, the first input total optical power and the second input total optical power respectively. Among them, the first input total optical power is equal to "the total value of the input optical powers of other optical channels + the first input optical power", and the second input total optical power is equal to "the total value of the input optical powers of other optical channels + the second input optical power"; similarly, when the first detection optical signal and the second detection optical signal are respectively input, the optical powers obtained at the output detection point are the first output total optical power and the second output total optical power respectively. Among them, the first output total optical power is equal to "the total value of the output optical powers of other optical channels + the first output optical power", and the second output total optical power is equal to "the total value of the output optical powers of other optical channels + the second output optical power".

[0116] When the OTN works stably, it can be considered that except for the target optical channel, the optical signals in other optical channels are generally stable, that is, at different times, at the same position, the total value of the optical powers of other optical channels remains unchanged.

[0117] Thus, it can be considered that the above "total value of the input optical powers of other optical channels" is a fixed value (fixed input optical power M), and the "total value of the output optical powers of other optical channels" is also a fixed value (fixed output optical power N). Therefore, there are:

[0118] The first input total optical power = M + PA1;

[0119] The first output total optical power = N + PB1;

[0120] The second input total optical power = M + PA2;

[0121] The second output total optical power = N + PB2;

[0122] Furthermore, there are:

[0123] M + PA1 - N - PB1 - M - PA2 + N + PB2 = PA1 - PB1 - PA2 + PB2 = ΔP.

[0124] That is, ΔP can also be calculated by the first total input optical power, the first total output optical power, the second total input optical power, and the second total output optical power.

[0125] Therefore, in the embodiments of the present disclosure, instead of separately detecting the optical power of the target optical channel, the first total input optical power, the first total output optical power, the second total input optical power, and the second total output optical power of all optical channels can be directly detected, and ΔP can be directly calculated using these total optical powers.

[0126] According to the above method, as long as detection points are set at the total ports (such as multiplexing ports) of all optical channels, the frequency offset of any optical bandpass device (or any port of the optical bandpass device) can be detected, so that richer functions can be realized through a simple system.

[0127] It should be understood that the premise of the above method is that "the total value of the optical power of other optical channels remains unchanged (that is, there is a fixed input optical power and a fixed output optical power)", so it can be carried out at night or other times when the overall optical signal volume is small and stable.

[0128] In some embodiments, when a first detection optical signal is input to the target optical channel, obtaining the first total input optical power at the input detection point and obtaining the first total output optical power at the output detection point (S102BB1) includes:

[0129] S102BB11. When a first detection optical signal is input to the target optical channel, multiple instantaneous first total input optical powers are detected at the input detection point, and multiple instantaneous first total output optical powers are detected at the output detection point; the mean value of the multiple instantaneous first total input optical powers is determined as the first total input optical power, and the mean value of the multiple instantaneous first total output optical powers is determined as the first total output optical power.

[0130] When a second detection optical signal is input to the target optical channel, obtaining the second total input optical power at the input detection point and obtaining the second total output optical power at the output detection point (S102BB2) includes:

[0131] S102BB21. When a second detection optical signal is input to the target optical channel, multiple instantaneous second total input optical powers are detected at the input detection point, and multiple instantaneous second total output optical powers are detected at the output detection point; the mean value of the multiple instantaneous second total input optical powers is determined as the second total input optical power, and the mean value of the multiple instantaneous second total output optical powers is determined as the second total output optical power.

[0132] As a way of the embodiments of the present disclosure, for each of the above total optical powers (the first input total optical power, the second input total optical power, the first output total optical power, the second output total optical power), the instantaneous values (the instantaneous first input total optical power, the instantaneous second input total optical power, the instantaneous first output total optical power, the instantaneous second output total optical power) can be detected multiple times under the same conditions, and then the average value is taken as the final result.

[0133] As mentioned above, the premise of the above method is that "the total value of the optical powers of other optical channels remains unchanged". In actual work, the total value of the optical powers of other optical channels generally fluctuates, but on average it should remain unchanged. Therefore, the method of detecting multiple times and taking the average can better achieve "the total value of the optical powers of other optical channels remains unchanged" and reduce or eliminate errors.

[0134] In the embodiments of the present disclosure, the specific detection methods for the input and output optical powers (including the optical power of the target optical channel and the total optical power; including specific optical power values and optical power distribution spectra) are diverse.

[0135] For example, an optical power detection module can be externally connected to the detection points (input detection point, output detection point) of the target optical channel, such as at specific positions inside a splitter, WSS, AWG, optical demultiplexing unit (ODU), optical multiplexing unit (OMU), etc., or outside a specific port, and the optical power detection module is connected.

[0136] Among them, the optical power detection module can be a device such as a photodetector or a spectrometer for detecting the specific optical power at one frequency, or it can be a device such as an optical performance monitor (OPM) that can directly detect the optical power distribution spectrum.

[0137] Alternatively, the devices passed by the target optical channel can obtain the optical powers at specific positions inside themselves, so these positions can be directly used as the corresponding detection points (input detection point, output detection point). For example, the multiplexing ports of a splitter / WSS / AWG / ODU / OMU, the monitoring ports of an OA, the demultiplexing ports of a power distribution unit (PDU), etc. are used as detection points.

[0138] Example 1:

[0139] Next, a method for detecting frequency offset provided by the embodiments of the present disclosure will be specifically introduced.

[0140] In this Example 1, the method of accessing and detecting the light source through the local port is adopted. The applicable OTN structure can be referred to Figure 7 of.

[0141] Among them, there are bi-directional services in the OTN. The optical paths and devices passed by the bi-directional services can be regarded as two independent unidirectional optical paths, and the methods of the embodiments of the present disclosure can be respectively used for processing. Only one direction is introduced in this Example 1.

[0142] Referring to Figure 7 , site P and site Q are ROADM sites that are direction-independent and wavelength-dependent. The transmitting end is site P, and the receiving end is site Q. The optical channel includes multiple optical bandpass devices such as WSS, OMU, and ODU in each site, and may also include other devices such as multiple OAs.

[0143] Taking the WSS in site P to be detected as an example, the input port of the Splitter of site P can be used as the input detection point (point A), and the corresponding output port of the WSS can be used as the output detection point (point B).

[0144] In the drawings of the embodiments of the present invention (such as Figure 7 , Figure 8 etc.), the marked positions of the detection points only indicate their relative positions in the optical path, rather than their true physical positions.

[0145] For example, the detection point can be on the connection structure (such as an optical fiber) between the devices on both sides, or it can also be directly inside the device (such as the device itself has the function of detecting the optical power at a specific position).

[0146] Among them, it is assumed that the center frequency of the target optical channel is 192.1 THz and the width is 50 GHz, that is, the frequency range of the target optical channel is 192.075 - 192.125 THz.

[0147] It is assumed that when the service light enters the OMU, the optical power within 50 GHz is 1 dBm, and the narrowband optical power with a bandwidth of 12.5 GHz is adjusted to -5 dBm.

[0148] Correspondingly, the method for detecting frequency offset in this Example 1 includes:

[0149] A101. Determine the target optical channel passing through the target WSS (target optical bandpass device), connect the detection light source to the corresponding idle input port of the OMU of site P, and connect the photodetector to the corresponding idle output port of site Q.

[0150] Among them, the other ports of the OMU of site P and the ODU of site Q are not idle, but are connected to the optical conversion unit (OTU, Optical Transform Unit).

[0151] A102. Configure the optical filter module in the detection light source, and set the left and right narrow-band lights output therefrom to be respectively:

[0152] Narrow-band light #1: 192.075 - 192.0875 THz (first detection optical signal);

[0153] Narrow-band light #2: 192.1125 - 192.125 THz (second detection optical signal).

[0154] A103. Set the passbands of the WSS at site P to the frequency bands of narrow-band light #1 and narrow-band light #2 respectively in chronological order, and perform corresponding optical power detections respectively.

[0155] Among them, when narrow-band light #1 is input, the input port of the Splitter automatically obtains PA1, and PB1 is detected through a photodetector.

[0156] Among them, when narrow-band light #2 is input, the input port of the Splitter automatically obtains PA2, and PB2 is detected through a photodetector.

[0157] A104. Calculate △P1 and △P2 respectively according to △P1 = PA1 - PB1 and △P2 = PA2 - PB2.

[0158] A105. Calculate △P according to △P = △P1 - △P2.

[0159] A106. Find the corresponding frequency offset value according to △P as the frequency offset detection result of the WSS.

[0160] A107. Analyze the possible deterioration degree of the service according to the frequency offset, and optimize relevant parameters in advance to ensure the service quality.

[0161] Example 2:

[0162] The following specifically introduces a method for detecting frequency offset provided by an embodiment of the present disclosure.

[0163] The OTN structure applicable to this Example 2 can refer to Figure 8 .

[0164] Among them, the OTN structure and the method for detecting frequency offset in this Example 2 are similar to those in Example 1, the difference being that it adopts a method of accessing the detection light source through remote ports, that is:

[0165] (1) The OTN includes two transmitting sites R, site P, and one receiving site Q.

[0166] (2) The detection light source is connected to the corresponding input port of the add / drop unit at site R, while the input detection point (point A) and the output detection point (point B) can be set remotely relative to the detection light source, both located in site P and externally connected to an OPM.

[0167] In a second aspect, referring to Figure 3 , an embodiment of the present disclosure provides a device for frequency offset detection, which includes:

[0168] A detection light source, which is used to connect to a target optical channel and input a first detection optical signal and a second detection optical signal with different frequencies to the target optical channel; the target optical channel is an idle optical channel passing through a target optical bandpass device;

[0169] A detection module, which is configured to: obtain the first input optical power of the first detection optical signal and the second input optical power of the second detection optical signal at the input detection point, and obtain the first output optical power of the first detection optical signal and the second output optical power of the second detection optical signal at the output detection point; wherein, in the target optical channel, the input detection point is located between the detection light source and the target optical bandpass device, and the output detection point is located after the target optical bandpass device; and determine the frequency offset of the target optical bandpass device according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power.

[0170] Those of ordinary skill in the art can understand that all or some of the steps, systems, and functional modules / units in the devices disclosed above can be implemented as software, firmware, hardware, and their appropriate combinations.

[0171] In a hardware implementation, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component can have multiple functions, or a function or step can be executed by several physical components in cooperation.

[0172] Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit (CPU), a digital signal processor, or a microprocessor, or may be implemented as hardware, or may be implemented as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, random access memory (RAM, more specifically SDRAM, DDR, etc.), read only memory (ROM), electrically erasable programmable read only memory (EEPROM), flash memory (FLASH), or other magnetic disk storage; compact disc read only memory (CD-ROM), digital versatile disc (DVD), or other optical disk storage; magnetic cassette, tape, magnetic disk storage, or other magnetic storage; and any other medium that can be used to store the desired information and that can be accessed by a computer. Additionally, as is well known to those of ordinary skill in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0173] The present disclosure has disclosed example embodiments, and although specific terms have been employed, they are used only and should be construed only for general illustrative purposes and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly stated, features, characteristics, and / or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and / or elements described in connection with other embodiments. Accordingly, those skilled in the art will understand that various forms and details may be changed without departing from the scope of the present disclosure as set forth by the appended claims.

Claims

1. A method for frequency offset detection, wherein, it includes: detecting a first detection optical signal and a second detection optical signal with different frequencies input by a light source to a target optical channel; the target optical channel is an idle optical channel passing through a target optical bandpass device; acquiring a first input optical power of the first detection optical signal and a second input optical power of the second detection optical signal at an input detection point, and acquiring a first output optical power of the first detection optical signal and a second output optical power of the second detection optical signal at an output detection point; wherein, in the target optical channel, the input detection point is located between the detection light source and the target optical bandpass device, and the output detection point is located after the target optical bandpass device; determining the frequency offset of the target optical bandpass device according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power.

2. The method according to claim 1, wherein, the determining the frequency offset of the target optical bandpass device according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power includes: determining an optical power difference according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power; the optical power difference is the difference between a first optical power loss and a second optical power loss, the first optical power loss is the difference between the first input optical power and the first output optical power, and the second optical power loss is the difference between the second input optical power and the second output optical power; determining the frequency offset of the target optical bandpass device according to the optical power difference.

3. The method according to claim 1, wherein, the detection light source includes: a doped optical amplification module and an optical filter module connected to the output end of the doped optical amplification module; the detecting a first detection optical signal and a second detection optical signal with different frequencies input by a light source to a target optical channel includes: outputting a broadband optical signal to the optical filter module through spontaneous emission of the doped optical amplification module; performing a first filtering operation on the broadband optical signal through the optical filter module to obtain the first detection optical signal, and inputting the first detection optical signal into the target optical channel, and performing a second filtering operation on the broadband optical signal through the optical filter module to obtain the second detection optical signal, and inputting the second detection optical signal into the target optical channel.

4. The method according to claim 3, wherein, the doped optical amplification module includes: a doped fiber amplifier; or, a plurality of cascaded doped fiber amplifiers.

5. The method according to claim 1, wherein, the first detection optical signal is a narrowband light, the second detection optical signal is a narrowband light, and the narrowband light of the first detection optical signal and the narrowband light of the second detection optical signal are symmetrically distributed with respect to the center frequency of the target optical channel.

6. The method according to claim 1, wherein, the detecting a first detection optical signal and a second detection optical signal with different frequencies input by a light source to a target optical channel includes: Input the first detection optical signal and the second detection optical signal into the target optical channel simultaneously through the detection light source.

7. The method according to claim 6, wherein, the obtaining the first input optical power of the first detection optical signal and the second input optical power of the second detection optical signal at the input detection point, and obtaining the first output optical power of the first detection optical signal and the second output optical power of the second detection optical signal at the output detection point includes: Obtain the input optical power distribution spectrum at the input detection point, and obtain the output optical power distribution spectrum at the output detection point; Determine the first input optical power and the second input optical power according to the input optical power distribution spectrum, and determine the first output optical power and the second output optical power according to the output optical power distribution spectrum.

8. The method according to claim 1, wherein, the inputting the first detection optical signal and the second detection optical signal with different frequencies into the target optical channel through the detection light source includes: Input the first detection optical signal and the second detection optical signal into the target optical channel at different times respectively through the detection light source.

9. The method according to claim 8, wherein, the obtaining the first input optical power of the first detection optical signal and the second input optical power of the second detection optical signal at the input detection point, and obtaining the first output optical power of the first detection optical signal and the second output optical power of the second detection optical signal at the output detection point includes: When inputting the first detection optical signal into the target optical channel, obtain the first input optical power at the input detection point and obtain the first output optical power at the output detection point; When inputting the second detection optical signal into the target optical channel, obtain the second input optical power at the input detection point and obtain the second output optical power at the output detection point.

10. The method according to claim 8, wherein, when multiple optical channels including the target optical channel pass through the input detection point and the optical channels passing through the output detection point are the same as those passing through the input detection point; the obtaining the first input optical power of the first detection optical signal and the second input optical power of the second detection optical signal at the input detection point, and obtaining the first output optical power of the first detection optical signal and the second output optical power of the second detection optical signal at the output detection point includes: When inputting the first detection optical signal into the target optical channel, obtain the first total input optical power at the input detection point and obtain the first total output optical power at the output detection point; the first total input optical power includes a fixed-value input optical power and the first input optical power, and the first total output optical power includes a fixed-value output optical power and the first output optical power; When the second detection optical signal is input into the target optical channel, obtain the second total input optical power at the input detection point and the second total output optical power at the output detection point; the second total input optical power includes the fixed-value input optical power and the second input optical power, and the second total output optical power includes the fixed-value output optical power and the second output optical power.

11. The method according to claim 10, wherein, when the first detection optical signal is input into the target optical channel, obtaining the first total input optical power at the input detection point and the first total output optical power at the output detection point includes: when the first detection optical signal is input into the target optical channel, detecting a plurality of instantaneous first total input optical powers at the input detection point and detecting a plurality of instantaneous first total output optical powers at the output detection point; determining the mean value of the plurality of instantaneous first total input optical powers as the first total input optical power, and determining the mean value of the plurality of instantaneous first total output optical powers as the first total output optical power; when the second detection optical signal is input into the target optical channel, obtaining the second total input optical power at the input detection point and the second total output optical power at the output detection point includes: when the second detection optical signal is input into the target optical channel, detecting a plurality of instantaneous second total input optical powers at the input detection point and detecting a plurality of instantaneous second total output optical powers at the output detection point; determining the mean value of the plurality of instantaneous second total input optical powers as the second total input optical power, and determining the mean value of the plurality of instantaneous second total output optical powers as the second total output optical power.

12. A device for frequency offset detection, wherein, comprising: a detection light source, which is used to connect to a target optical channel and input a first detection optical signal and a second detection optical signal with different frequencies into the target optical channel; the target optical channel is an idle optical channel passing through a target optical bandpass device; a detection module, which is configured to: obtain the first input optical power of the first detection optical signal and the second input optical power of the second detection optical signal at the input detection point, and obtain the first output optical power of the first detection optical signal and the second output optical power of the second detection optical signal at the output detection point; wherein, in the target optical channel, the input detection point is located between the detection light source and the target optical bandpass device, and the output detection point is located after the target optical bandpass device; and determining the frequency offset of the target optical bandpass device according to the first input optical power, the first output optical power, the second input optical power, and the second output optical power.

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