CN115833954A

CN115833954A - Wavelength calibration method and device

Info

Publication number: CN115833954A
Application number: CN202111087679.9A
Authority: CN
Inventors: 忻海云; 马会肖; 郑博方
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-09-16
Filing date: 2021-09-16
Publication date: 2023-03-21

Abstract

The application provides a wavelength calibration method and a wavelength calibration device, which comprise the following steps: acquiring a reference optical signal; adjusting the output wavelength of the local laser according to the reference optical signal to generate a reference optical signal, wherein the wavelength of the reference optical signal is the same as that of the reference optical signal; generating a plurality of target optical signals based on the reference optical signal, each of the plurality of target optical signals having a different wavelength, each of the target optical signals having a different and fixed frequency difference from the reference optical signal; a first target optical signal is extracted from a plurality of target optical signals for data transmission. The wavelength calibration method enables the optical signal of the transmission data to keep synchronous with the reference optical signal, and further enables the wavelengths of all nodes of the whole network for data transmission to keep synchronous.

Description

Wavelength calibration method and device

Technical Field

The present application relates to the field of optical communications, and more particularly, to a wavelength calibration method and apparatus.

Background

With the continuous development of optical communication systems, optical fiber networks face dual requirements of high bandwidth and flexible intelligence. Currently, wavelength Division Multiplexing (WDM) techniques using a fixed grid will result in a too low spectrum utilization. Therefore, the flexible grid is introduced such that the signals of different network nodes are spectrally closely spaced, thereby maximizing spectral utilization.

However, in flexible grid deployments, signal impairments such as crosstalk limit the setting of the minimum guard band gap between spectra. Because the lasers of different optical network nodes in the optical fiber network are mutually independent and have higher random frequency difference, the problems of frequency spectrum aliasing, signal quality degradation and the like are inevitably caused.

Therefore, how to ensure that the optical network node has a stable frequency difference, and further improve the utilization efficiency of the network spectrum is an urgent problem to be solved.

Disclosure of Invention

The application provides a wavelength calibration method and device, which can ensure that an optical network node has a stable frequency error, and further improve the utilization efficiency of a network frequency spectrum.

In a first aspect, a method for wavelength calibration is provided, including: acquiring a reference optical signal; adjusting the output wavelength of the local laser according to the reference optical signal to generate a reference optical signal, wherein the wavelength of the reference optical signal is the same as that of the reference optical signal; generating a plurality of target optical signals based on the reference optical signal, each of the plurality of target optical signals having a different wavelength, each of the target optical signals having a different and fixed frequency difference from the reference optical signal; a first target optical signal is extracted from a plurality of target optical signals for data transmission.

According to the scheme provided by the application, reference light is obtained, reference light is generated according to the reference light, and then a first target light signal with stable frequency difference with the reference light is generated and used for loading data during self work. The method is suitable for each network node of the system, adopts the uniform wavelength reference to carry out wavelength calibration, and can ensure that the optical network nodes have stable frequency error, so that the network reduces the protection band gap when adopting flexible grid deployment, improves the utilization efficiency of the network frequency spectrum, and further ensures the signal transmission quality.

The technical scheme of the application is applied to the elastic optical network, such as a multi-level ring network structure. After the wavelength calibration is carried out on the whole network, the frequency spectrum interval of the laser wavelength among all network nodes is stable, so that the frequency spectrum aliasing caused by the random frequency difference of the laser is avoided, the guard band interval among the frequency spectrums can be cancelled, and the frequency spectrum utilization rate is improved. Compared with the traditional optical network, the all-optical network has stronger flexibility, transparency, compatibility and expansibility. In addition, under the condition of ensuring wavelength synchronization, the signal at each network node is connected with the down-path, and the sub-band level optical switching can also be flexibly realized.

It should be noted that the reference optical signal and the reference optical signal have the same wavelength. In order to ensure the current network Node due to signal distortion or path loss difference _X The medium wavelength calibration and the signal transmission quality need to adjust the wavelength of the local laser according to the reference light, so as to obtain the reference light with higher signal quality, thereby realizing the subsequent wavelength calibration mechanism.

For example, the reference optical signal may refer to a wavelength λ ₀ Continuous dc optical signal.

With reference to the first aspect, in certain implementations of the first aspect, acquiring the reference light signal includes: receiving a first signal, wherein the first signal is a light signal received by a current network node from a network node before the current network node; the reference optical signal is filtered from the first signal.

It should be understood that the wavelength calibration method of the present application is mainly directed to a mechanism for performing full-network wavelength synchronization between network nodes in one transmission direction with reference to the wavelength of the same reference optical signal. Therefore, the whole transmission process of the current network node receiving a signal from a network node previous to the current network node and sending a signal to a network node next to the current network node after acquiring the first target optical signal is unidirectional. That is, for the current network node, one pair of transceiving interfaces corresponds to one transmission direction.

It should be noted that, front and back in the embodiments of the present application mainly refer to front and back in the signal transmission direction, including but not limited to a relationship in physical location. Illustratively, the network node preceding the current network node includes, but is not limited to, a network system architecture deployed at a position directly in front of the current node position. For example, the node that is physically connected directly to the current network node a may be the previous network node B, or may be another device C (e.g., an interface device, or a bridge device). Wherein the other device C may be directly or indirectly communicatively interconnected with the previous network node B.

The first signal may be a wavelength division multiplexing signal, which is not limited in this application.

In this implementation, the current network node acquires a first signal from a network node previous to the current network node, and filters out the reference optical signal from the first signal. Reference light signals for wavelength calibration are generated based on the reference light. With the transmission of signals, all network nodes carry out the calibration, and finally, the full-network wavelength synchronization is realized.

It should be noted that the sources of the reference optical signals in the current network nodes in different application scenarios are different. For the reference optical signal in the tree topology, the reference optical signal mainly comes from a signal transmitted by a previous node. For example, in a wavelength division multiplexing passive optical network (WDM-PON), a downstream signal transmitted from an Optical Line Terminal (OLT) to an Optical Network Unit (ONU), a signal transmitted from a root node to a leaf node in a Data Center (DC), and the like are transmitted. For the reference optical signal in the ring topology, the signal mainly comes from the previous node. This is not a specific limitation in the present application.

With reference to the first aspect, in certain implementations of the first aspect, the form of the reference light signal includes one of direct current continuous light, low-speed intensity modulated continuous light, and low-order coherent modulated continuous light.

In this implementation, the reference optical signal has more diversified forms, and the low-speed intensity modulated continuous light and the low-order coherent modulated continuous light for loading the data signal are added.

It should be noted that, in the technical solution of the present application, the device structure of the frequency calibration unit is adapted according to the form of the reference light. For example, in the case that the reference optical signal is in the form of direct current continuous light, a wavelength locking technique or an injection locking technique is adopted; for the case that the reference optical signal is in the form of low-order coherent modulated light, the laser frequency of the current network node is feedback-adjusted by extracting the phase difference, so as to implement optical frequency calibration, for example, an optical phase-locked loop scheme.

With reference to the first aspect, in certain implementations of the first aspect, adjusting an output wavelength of the local laser according to the reference optical signal to generate a reference optical signal includes: when the reference optical signal is in the form of direct continuous light, the output wavelength of the local laser is adjusted according to a wavelength locking technique or an injection locking technique to generate the reference optical signal.

In this implementation, for the case where the reference light is in the form of direct-current continuous light, the reference light signal is generated by using a wavelength locking technique or an injection locking technique (IL). The implementation mode can realize the aim of wavelength calibration and accurately determine the reference optical signal.

It will be appreciated that when the reference optical signal is in the form of dc continuous light, it is easiest to extract the wavelength reference.

For example, the current network node filters and extracts a reference optical signal from the received signal by using a Fiber Bragg Grating (FBG) that satisfies a wavelength matching condition. That is, the reference optical signal goes through the reflection path, and the rest spectrum is transmitted through the FBG for demodulation or continuous transmission. Since the injection locking technique can amplify the injected wavelength while suppressing other sidebands, it is equivalent to active very narrow bandwidth filtering.

With reference to the first aspect, in certain implementations of the first aspect, adjusting an output wavelength of the local laser according to the reference optical signal to generate a reference optical signal includes: when the form of the reference optical signal is low-speed intensity modulation continuous light, the reference optical signal is coupled with an output optical signal input coupler of the local laser; inputting the coupled optical signals into a balance detector to obtain a phase difference; and adjusting the optical frequency of the local laser according to the phase difference feedback to generate a reference optical signal.

In this implementation, for the case that the reference light is in the form of low-speed intensity modulated continuous light, a coupler and balanced detection are adopted to obtain a phase difference, and then a reference light signal is generated. This implementation enables frequency calibration with reference light modulation data. This makes some low-speed control signaling can pass through reference light signal transmission, has improved the utilization ratio of resource.

With reference to the first aspect, in certain implementations of the first aspect, adjusting an output wavelength of the local laser according to the reference optical signal to generate a reference optical signal includes: when the form of the reference optical signal is low-order coherent modulation continuous light, the reference optical signal and the output optical signal of the local laser are input into a 90-degree optical mixer to obtain an in-phase component and a quadrature component of the optical signal; determining a phase difference of the optical signal according to the in-phase component and the quadrature component of the optical signal; and adjusting the optical frequency of the local laser according to the phase difference feedback of the optical signal to generate a reference optical signal.

In this implementation, for the case that the reference light is in the form of low-order coherent modulated continuous light, a 90 ° optical mixer is adopted to obtain an in-phase component and a quadrature component, and determine a phase difference of the optical signals, thereby generating the reference optical signal. The implementation is carried out at a reference light lambda ₀ The data is modulated, the utilization rate of resources is improved, and compared with an intensity modulation mode, the method can realize the transmission of signaling data with higher speed and improve the transmission quality of the signaling data.

With reference to the first aspect, in certain implementations of the first aspect, when the reference light signal is in the form of dual light waves, the wavelengths of the dual light waves are λ ₀ And λ ₀ + Δ f, the method further comprising: according to wavelength of λ ₀ Adjusts the output wavelength of the first local laser to generate a reference optical signal having a wavelength λ ₀ The reference optical signal of (a); according to wavelength of λ ₀ The + Δ f reference optical signal adjusts the output wavelength of the second local laser to generate a reference optical signal having a wavelength λ ₀ Optical signal of + Δ f, second local laser output wavelength λ ₀ The optical signal of + Δ f has a wavelength λ corresponding to the output of the first local laser ₀ A part of the optical signal of the reference light is beat-frequency to obtain an electrical signal with a frequency Δ f.

In this implementation, a wavelength reference is provided, along with a reference to the frequency of the electrical signal. Compared with the current method of recovering the clock from the data and further extracting the reference, the circuit part has simple structure.

In the embodiment of the present application, the beat frequency is also referred to as a photo-diode beat (PD beat) and means that two optical signals with different wavelengths enter a PD, and the PD outputs an electrical tone signal, where the frequency of the tone signal is the same as the frequency difference of the optical signals.

With reference to the first aspect, in some implementations of the first aspect, the first target optical signal is loaded with data, and is coupled with the reference optical signal and a second signal and then sent to a subsequent network node, where the second signal is an optical signal directly transmitted to the subsequent network node in the first signal.

In this implementation, there is a stable frequency difference between the first target optical signal and the reference optical signal, and the transfer of the wavelength reference is completed. With the transmission of signals, all network nodes carry out the calibration, and finally, the full-network wavelength synchronization is realized.

Illustratively, the wavelength division multiplexed signal received by the current network node from the node preceding the current network node includes three parts, one part is a signal to be resolved locally, one part is a signal to be transmitted to the next network node, and the other part is a reference optical signal used for the optical frequency reference of the present application. The current network node, after acquiring the optical frequency reference, uses a frequency calibration device to generate the wavelength of its own transmitted data, i.e. the first target optical signal. After the first target signal modulates the data, the data is combined with the wavelength reference signal and other signals transmitted to the next network node, and the signals are sent to the next network node.

With reference to the first aspect, in certain implementations of the first aspect, generating a plurality of target light signals based on the reference light signal includes: a plurality of target optical signals are generated based on a reference optical signal by an Optical Frequency Comb (OFC) technique.

In this implementation manner, the frequency extension unit may ensure that a plurality of target optical signals having relatively stable frequency differences with the reference optical signal are obtained by using the OFC technology, and the wavelength used for its own operation, that is, the first target optical signal, is determined by using the frequency selection unit according to the actual operation requirement of the current network node.

This is because each spectral line in the plurality of target optical signals acquired by the OFC technique has a fixed frequency difference from the reference light. Moreover, the OFC technology is easy to obtain larger frequency difference, so that the system can work in a large wavelength range, and the adjustability of the frequency of small particles and the integration miniaturization are realized.

It is understood that OFC techniques refer to a spectrum that is spectrally composed of a series of uniformly spaced frequency components with coherently stable phase relationships. The OFC is widely used due to its characteristics in optical arbitrary waveform generation, multi-wavelength ultrashort pulse generation, dense wavelength division multiplexing, and the like.

With reference to the first aspect, in certain implementations of the first aspect, extracting a first target optical signal from a plurality of target optical signals includes: the plurality of target optical signals are extracted from the optical frequency comb into a first target optical signal according to an injection-locked IL technique or a tunable optical filter cascade optical amplifier technique.

In this implementation, the frequency selection unit may extract the first target optical signal suitable for its own operating wavelength through an IL technique or a tunable optical filter cascade optical amplifier technique. Compared with the traditional optical network system, the wavelength selection in the whole network wavelength calibration mechanism is more flexible and the adaptability is stronger.

Illustratively, the first target optical signal is extracted from the broadband optical comb using an injection locking technique. The method specifically comprises the following steps: the wide-spectrum optical comb is injected into the local laser through the circulator port, and the wavelength of the local laser is adjusted to be within a locking range by a Micro Controller Unit (MCU). Due to the principle of injection locking technology, the laser finally generates a standard first target optical signal, which is output through the circulator port. And finally, modulating data by using the first target optical signal as a carrier. The operating wavelength of each network node can be flexibly selected by adjusting the target optical signal.

Illustratively, the frequency selective function is achieved by a technique in which optical filters are cascaded with optical amplifiers. Firstly, a first target optical signal required is filtered out from a frequency comb by using a tunable optical filter, then the power is improved by using an optical amplifier, and finally the first target optical signal enters an optical modulator. Based on the first target optical signal, a data signal can be loaded, and the quality of signal transmission is improved.

In a second aspect, there is provided an apparatus for wavelength calibration, comprising: a processing unit for acquiring a reference light signal; the frequency calibration unit is used for adjusting the output wavelength of the local laser according to the reference optical signal to generate a reference optical signal, and the wavelength of the reference optical signal is the same as that of the reference optical signal; a frequency expanding unit configured to generate a plurality of target optical signals based on the reference optical signal, each of the plurality of target optical signals having a different wavelength, and each of the target optical signals having a different and fixed frequency difference from the reference optical signal; and the frequency selection unit is used for extracting the first target optical signal from the plurality of target optical signals so as to carry out data transmission.

With reference to the second aspect, in certain implementations of the second aspect, the apparatus further includes: the receiving and sending unit is used for receiving a first signal, wherein the first signal is a light signal received by a current network node from a previous network node of the current network node; and the processing unit is also used for filtering and extracting the reference light signal from the first signal.

It should be noted that, front and back in the embodiments of the present application mainly refer to front and back in the signal transmission direction, including but not limited to a relationship in physical location. Illustratively, a network node preceding the current network node includes, but is not limited to, a location directly in front of the current node location under the network system architecture. For example, the node that is physically connected directly to the current network node a may be the previous network node B, or may be another device C (e.g., an interface device, or a bridge device). Wherein the other device C may be directly or indirectly communicatively interconnected with the previous network node B.

The first signal may be a wavelength division multiplexing signal, which is not particularly limited in this application.

In this implementation, the current network node acquires a first signal from a previous network node and filters out a reference optical signal from the first signal. Reference light signals for wavelength calibration are generated based on the reference light. With the transmission of signals, all network nodes carry out the calibration, and finally, the full-network wavelength synchronization is realized.

It should be noted that the sources of the reference optical signals in the current network nodes in different application scenarios are different. For the reference optical signal in the tree topology, the reference optical signal mainly comes from a signal transmitted by a previous node. For example, in a wavelength division multiplexing passive optical network WDM-PON, a downstream signal transmitted from an Optical Line Terminal (OLT) to an Optical Network Unit (ONU), a signal transmitted from a root node in a Data Center (DC) to a leaf node, and the like are transmitted. For a reference optical signal in a ring topology, the signal mainly comes from the previous node. This is not a particular limitation of the present application.

With reference to the second aspect, in certain implementations of the second aspect, the form of the reference light signal includes one of direct current continuous light, low-speed intensity modulated continuous light, and low-order coherent modulated continuous light.

It should be noted that, in the technical solution of the present application, the device structure of the frequency calibration unit is adapted according to the form of the reference light. For example, in the case that the reference optical signal is in the form of direct current continuous light, a wavelength locking technique or an injection locking technique is adopted; for the case that the reference optical signal is in the form of low-order coherent modulation light, the laser frequency of the current network node is feedback-adjusted by extracting the phase difference, so as to realize optical frequency calibration, such as an optical phase-locked loop scheme.

With reference to the second aspect, in certain implementations of the second aspect, when the reference optical signal is in the form of direct-current continuous light, the frequency calibration unit is further configured to adjust an output wavelength of the local laser according to a wavelength locking technique or an injection locking technique to generate the reference optical signal.

In this implementation, for the case where the reference light is in the form of direct-current continuous light, the reference light signal is generated by using a wavelength locking technique or an injection locking technique IL. The implementation mode can realize the aim of wavelength calibration and accurately determine the reference optical signal.

It will be appreciated that when the reference optical signal is in the form of a dc continuous light, it is easiest to extract the wavelength reference.

For example, the current network node filters and extracts a reference optical signal from the received signal by using a Fiber Bragg Grating (FBG) that satisfies a wavelength matching condition. That is, the reference optical signal goes through the reflection path, and the rest spectrum is transmitted through the FBG for demodulation or continuous transmission. Since the injection locking technique can amplify the injected wavelength while suppressing the other sidebands, it is equivalent to an active very narrow bandwidth filtering.

With reference to the second aspect, in some implementations of the second aspect, the frequency calibration unit is further configured to couple the reference optical signal with an output optical signal input coupler of the local laser when the reference optical signal is in the form of low-speed intensity modulated continuous light; inputting the coupled optical signals into a balance detector to obtain a phase difference; and adjusting the optical frequency of the local laser according to the phase difference feedback to generate a reference optical signal.

With reference to the second aspect, in certain implementations of the second aspect, when the reference optical signal is in the form of low-order coherent modulated continuous light, the frequency calibration unit is further configured to input the reference optical signal and the output optical signal of the local laser into a 90 ° optical mixer to obtain an in-phase component and a quadrature component of the optical signal; determining a phase difference of the optical signal according to the in-phase component and the quadrature component of the optical signal; and adjusting the optical frequency of the local laser according to the phase difference feedback of the optical signal to generate a reference optical signal.

With reference to the second aspect, in certain implementations of the second aspect, when the reference light signal is in the form of dual light waves, the wavelengths of the dual light waves are λ ₀ And λ ₀ + Δ f, frequency calibration unit, further for λ depending on the wavelength ₀ Adjusts the output wavelength of the first local laser to generate a reference optical signal having a wavelength λ ₀ The reference optical signal of (a); a frequency calibration unit for calibrating the frequency according to wavelength λ ₀ The + Δ f reference optical signal adjusts the output wavelength of the second local laser to generate a reference optical signal having a wavelength λ ₀ An optical signal of + Δ f, wherein the second local laser outputs at a wavelength λ ₀ The optical signal of + Δ f has a wavelength λ corresponding to the output of the first local laser ₀ A part of the optical signal of the reference light is beat-frequency to obtain an electrical signal with a frequency Δ f.

In this implementation, a wavelength reference is provided, along with a reference to the frequency of the electrical signal. Compared with the current method of recovering the clock from the data and further extracting the reference, the circuit part has a simple structure.

With reference to the second aspect, in some implementation manners of the second aspect, the transceiver unit is further configured to load data on the first target optical signal through the processing unit, couple the data with the reference optical signal and a second signal, and send the data to a subsequent network node, where the second signal is an optical signal directly transmitted to the subsequent network node in the first signal.

Illustratively, the wavelength division multiplexed signal received by the current network node from the previous node includes three parts, one part is a signal to be resolved locally, one part is a signal to be transmitted to the next network node, and the other part is a reference optical signal for the optical frequency reference of the present application. The current network node, after acquiring the optical frequency reference, uses a frequency calibration device to generate the wavelength of its own transmitted data, i.e. the first target optical signal. After the first target signal modulates data, the data is combined with the wavelength reference signal and other signals transmitted to the next network node, and the data is sent to the next network node.

With reference to the second aspect, in certain implementations of the second aspect, generating a plurality of target light signals based on the reference light signal includes: a plurality of target optical signals are generated based on a reference optical signal by an Optical Frequency Comb (OFC) technique.

This is because each of the spectral lines in the plurality of target optical signals acquired by the OFC technique has a fixed frequency difference from the reference light. Moreover, the OFC technology is easy to obtain larger frequency difference, so that the system can work in a large wavelength range, and the adjustability of small particle frequency and integration miniaturization are realized.

With reference to the second aspect, in certain implementations of the second aspect, extracting a first target optical signal from a plurality of target optical signals includes: the plurality of target optical signals are extracted from the optical frequency comb into a first target optical signal according to an injection-locked IL technique or a tunable optical filter cascade optical amplifier technique.

In this implementation, the frequency selection unit may extract the first target optical signal suitable for its own operating wavelength through an IL technique or a tunable optical filter cascade optical amplifier technique. Compared with the traditional optical network system, the wavelength selection in the whole network wavelength calibration mechanism is more flexible and has stronger adaptability.

Illustratively, the first target optical signal is extracted from the broadband optical comb using an injection locking technique. The method specifically comprises the following steps: and the broadband optical frequency comb is injected into the local laser through the port of the circulator, and the wavelength of the local laser is adjusted to a locking range by the MCU. Due to the principle of injection locking technology, the laser finally generates a standard first target optical signal, which is output through the circulator port. And finally, modulating data by using the first target optical signal as a carrier. The operating wavelength of each network node can be flexibly selected by adjusting the target optical signal.

In a third aspect, there is provided a full-network wavelength calibration apparatus, including a processor and optionally a memory, where the processor is configured to control a transceiver to transmit and receive signals, and the memory is configured to store a computer program, and the processor is configured to call and execute the computer program from the memory, so that the apparatus performs the method in any one of the foregoing first aspect or possible implementation manners of the first aspect.

Optionally, the number of the processors is one or more, and the number of the memories is one or more.

Alternatively, the memory may be integral to the processor or provided separately from the processor.

Optionally, the apparatus further comprises a transceiver, which may be in particular a transmitter (transmitter) and a receiver (receiver).

In a fourth aspect, there is provided an optical communication apparatus comprising: means or elements for implementing the method of the first aspect or any of its possible implementations.

In a fifth aspect, an optical communication system is provided, including: an optical network node configured to perform the method of the first aspect or any one of the possible implementations of the first aspect.

A sixth aspect provides a computer-readable storage medium storing a computer program or code, which when run on a computer causes the computer to perform the method of the first aspect or any of the possible implementations of the first aspect.

In a seventh aspect, a chip is provided, which includes at least one processor, the at least one processor is coupled with a memory, the memory is used to store a computer program, and the processor is used to invoke and run the computer program from the memory, so that an optical network node in which the chip system is installed executes the method in the first aspect or any one of the possible implementation manners of the first aspect.

Wherein the chip may comprise an input circuit or interface for transmitting information or data, and an output circuit or interface for receiving information or data.

In an eighth aspect, there is provided a computer program product comprising: computer program code which, when run by an optical network node, causes the optical network node to perform the method of the first aspect or any of the possible implementations of the first aspect.

According to the scheme of the embodiment of the application, the method and the device for full-network wavelength calibration are provided, reference light is obtained, reference light is generated according to the reference light, and then a first target light signal with stable frequency difference with the reference light is generated and used for loading data during self work. The method is suitable for each network node of the system, adopts the uniform wavelength reference to carry out wavelength calibration, and can ensure that the optical network nodes have stable frequency error, so that the network reduces the protection band gap when adopting flexible grid deployment, improves the utilization efficiency of the network frequency spectrum, and further ensures the signal transmission quality.

Drawings

Fig. 1 is a schematic diagram of an example of a multi-stage ring network architecture to which the present application is applied.

Fig. 2 is a schematic diagram of an example of the present wavelength calibration method.

Fig. 3 is a schematic diagram illustrating an example of a process for generating an on-frequency optical carrier from a wavelength reference by a slave node.

Fig. 4 is a schematic diagram showing an example of a wavelength calibration method to which the present invention is applied.

Fig. 5 is a schematic diagram illustrating an example of an operation principle of implementing wavelength calibration in a network node to which the present application is applied.

Fig. 6 is a schematic diagram showing an example of the operation principle of the wavelength calibration device to which the present invention is applied.

Fig. 7 is a schematic diagram of an example of an optical frequency calibration apparatus to which the present invention is applied.

Fig. 8 is another exemplary view of the optical frequency calibration apparatus to which the present application is applied.

Fig. 9 is a further exemplary view of the optical frequency calibration apparatus to which the present application is applied.

Fig. 10 is a schematic diagram of an example of an optical frequency selection device to which the present invention is applied.

Fig. 11 is a further explanatory view of the optical frequency calibration apparatus to which the present application is applied.

Fig. 12 is another schematic diagram illustrating a light frequency calibration device to which the present application is applied.

Fig. 13 is another explanatory view of the optical frequency calibration apparatus to which the present application is applied.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

The method is mainly applied to an Elastic Optical Network (EON). Fig. 1 is a schematic diagram of an example of a multi-stage ring network architecture to which the present application is applied. As shown in fig. 1, after the wavelength calibration is performed on the whole network, the spectrum interval of the laser wavelength between each network node is stable, which avoids the spectrum aliasing caused by the random frequency difference of the laser, and thus the guard interval between the spectra can be eliminated. For example, when data of the network node a and the network node B need to be aggregated to the network node C, two adjacent sections of spectra of the node a and the node B may be allocated, and the two sections of spectra are directly aggregated at the node C in a wave-combining manner. Then at node C, super channels (super channels) are formed, and the optical signals carrying information can be seamlessly spliced in spectrum.

Similarly, when the data of the network node C and the network node D need to be converged to the network node E, two adjacent sections of spectra of the node C and the node D may be allocated, and the two adjacent sections of spectra are directly converged at the node E in a wave-combining manner. This may be done when the data from each level of nodes is aggregated upward.

The realization mode can ensure the transmission of end-to-end all-optical information, replaces the traditional mode of arranging optical terminal equipment back to back, saves expensive electric relay cost and avoids the time delay generated by processing data at multiple levels. Meanwhile, compared with the traditional optical network, the all-optical network has stronger flexibility, transparency, compatibility and expandability. In addition, under the condition of ensuring wavelength synchronization, the signal at each node is added and dropped, and the sub-band level switching can also be flexibly realized.

To facilitate understanding of the embodiments of the present application, a brief description of several terms referred to in the present application will be given first.

1. Optical Phase Locked Loop (OPLL): the OPLL is a system for controlling the frequency of the output signal of a laser by signal phase feedback, so that the frequency of the slave laser tracks the frequency of the master laser and is consistent with the change of the frequency of the master laser, thereby realizing a constant output signal frequency difference. Similar to an electrical phase-locked loop, the optical phase-locked loop is divided into three parts, namely phase difference extraction, loop filtering and a voltage-controlled oscillator. Wherein, the voltage controlled oscillator is to control the frequency and phase of the laser by the output signal of the loop filter.

2. Injection Locking (IL): IL means that external light is input to one semiconductor light source through a circulator, and the wavelength of the injected light source is adjusted to be near one wavelength component (i.e., a target wavelength component) of the external input light so that the wavelength of the injected light source is within a lockable region of the target wavelength component. This implementation makes the final output optical frequency equal to the injected light because the laser source is internally similar to a frequency selective filter element, in that only the locked frequency component can oscillate inside it.

3. Elastic Optical Network (EON): conventional optical transport networks are based on WDM technology and have fixed spectral grids, one for each optical channel, with a fixed center frequency and spectral width. However, the WDM architecture has the disadvantages of low spectrum utilization, no dynamic adjustment of the optical channel, and inflexibility. Therefore, EON proposes breaking the constraint of a fixed spectrum grid in a conventional optical network. Through software control, the carrier center frequency can be located at any position on a frequency spectrum, and the distance-adaptive modulation format and the frequency spectrum width are achieved, so that the frequency spectrum utilization efficiency and the flexibility are improved.

4. Optical Frequency Comb (OFC): OFC refers to a spectrum, spectrally, consisting of a series of uniformly spaced frequency components with coherently stable phase relationships. OFC is usually generated by a mode-locked laser, and the expansion of frequency components can be achieved by a highly efficient nonlinear medium.

5. Metropolitan area network: the deployment of communication networks generally includes a backbone network-metropolitan area network-access network three-level architecture, and a national backbone network-metropolitan area network two-level architecture which is gradually presented in recent years. The backbone network mainly focuses on the transmission capacity, and the metropolitan area network plays a role in realizing effective access, grooming and convergence of various services. Meanwhile, the metropolitan area network not only needs to be compatible with various uplink and downlink signals, but also needs to have the bandwidth of corresponding services, and the cost is critical at a node.

The development requirements of the metropolitan area network include: scalability (i.e., flexibility, high efficiency, and strong scalability), sub-rate configuration (i.e., high bandwidth efficiency, and can meet the needs of more users), fast intelligent configuration (i.e., fast connection establishment), node transparency (i.e., support of multiple signal formats, and reduce the conversion cost), and the like.

6. Looped network: also known as ring networking. In a metropolitan area network wavelength division multiplexing system, a ring-shaped networking is adopted in most cases, and the self-healing protection function is achieved. The node uses Optical Add and Drop Module (OADM) to realize flexible uplink and downlink scheduling function.

7. Super channel (super channel): a superchannel has multiple optical wavelength signals, arranged spectrally close together, and typically transmitted and switched as a whole.

In order to facilitate understanding of the embodiments of the present application, the following description is made:

in the embodiments of the present application, unless otherwise specified or conflicting with respect to logic, the terms and/or descriptions in different embodiments have consistency and may be mutually cited, and technical features in different embodiments may be combined to form a new embodiment according to their inherent logic relationship.

In the present application, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that three relationships may exist. For example, a and/or B, may represent: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. In the description of the text of this application, the character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

In the embodiments of the present application, the "first", "second", and various numerical numbers indicate the distinction for the convenience of description, and do not limit the scope of the embodiments of the present application. For example, different indication information is distinguished.

In the embodiment of the application, the descriptions such as 'when 8230', 'when 8230; when', 'when 823030, in the case of' 8230 '\ 8230'; 'if' and 'if' refer to that the device performs corresponding processing under a certain objective condition, are not limited in time, do not require an action which is necessarily judged when the device is implemented, and do not mean that other limitations exist.

At present, with the development of science and technology, data traffic generated by services such as cloud computing, artificial intelligence, live broadcasting, short video and the like has the characteristics of high peak rate, rapid dynamic change and the like. Fiber optic networks, as the foundation of the overall communication system, are therefore also subject to the dual requirements of high bandwidth and flexible intelligence. In addition to traditional backbone networks, metropolitan area networks, and access networks, data networks in more and more scenarios have optical fiber transmission systems as the next generation of technology options. Such as the industrial internet, the car networking, etc. These optical networks all contain multiple network nodes with the need for multipoint-to-multipoint cooperative communication. Therefore, how to improve network flexibility is an important issue that must be solved by the optical fiber communication network, which includes flexible allocation of wavelength and bandwidth, efficient access of traffic at nodes, grooming and aggregation, and the like. Generally, optical networks employ fixed-grid wavelength division multiplexing WDM, where multiple multiplexed wavelengths can only use the same single rate for signal transmission, i.e., "rigid pipe" distribution. With the rise of bandwidth request diversity services and the development of optical network technology, the next generation optical network will be developed towards the flexible optical network trend of mixed rate and flexible grid. In an ideal flexible grid elastic optical network, signals from each network node should be arranged closely on the spectrum, so that the spectrum utilization efficiency is maximized, the limiting factors when the spectrum is allocated are reduced, and the flexibility of the network is improved.

However, physical layer signal impairments such as crosstalk limit the minimum guard band gap setting between spectra. The source of crosstalk includes adjacent channel crosstalk caused by factors such as non-ideal devices, and also includes nonlinear effects of optical fibers such as cross-phase modulation and four-wave mixing. For short-distance transmission scenes such as a metropolitan area network, an access network and an industrial network, the nonlinear effect of the optical fiber is not serious due to the fact that the transmission distance is not long. Therefore, adjacent channel crosstalk caused by non-ideal devices becomes a dominant factor influencing the setting of the minimum protection band gap. The influence of the random frequency difference of the lasers of different network nodes is most prominent, and the frequency difference range of the lasers specified in the 400G ZR standard reaches plus or minus 1.8GHz. For example, in a multipoint-to-point transmission architecture (e.g., XR optics) proposed by infirera, data of a plurality of Edge nodes are respectively loaded onto Nyquist shaping signals whose optical frequencies do not overlap with each other, spectrum aggregation is directly performed on an optical domain at a Hub node, and detection processing is performed through an optical receiver after the data are transmitted to a root node. However, since the lasers of the Edge have random frequency differences, the light convergence at the Hub node may cause spectrum aliasing, resulting in degraded signal quality. Therefore, this problem can be avoided in a frequency band-protected manner. However, the spectrum utilization efficiency also decreases, especially when the number of Edge nodes is large. Therefore, if the optical frequencies of the network nodes have a uniform reference, the limitation of network flexibility and spectrum utilization efficiency caused by random frequency difference of the lasers can be avoided.

Fig. 2 is a schematic diagram illustrating an example of a current wavelength calibration method. As shown in fig. 2, first, a network node is selected as a master node, and a set of spectra with stable wavelength distribution is generated at the master node as a wavelength reference (i.e., a frequency reference is generated). And then the wavelength references are respectively sent to the slave nodes. In each slave node, continuous optical signals with the same frequency are generated based on the reference light and are used as carriers for carrying data streams.

Specifically, an optical frequency comb signal is generated at the master node. Wherein, different spectral lines are respectively the wavelength reference of different slave nodes, and have stable frequency intervals with each other. The optical frequency comb signal is transmitted by the optical fiber and then distributed to the slave nodes.

It should be noted that the distribution process of the optical frequency comb signal is a two-stage filtering process. The first stage is passive filtering as shown in fig. 2, and a plurality of spectral lines are transmitted through one pass band of the splitter and then distributed to the slave nodes by the optical power splitter.

Fig. 3 is a schematic diagram illustrating an example of a process for generating an on-frequency optical carrier from a wavelength reference by a slave node, and the second stage is the active filtering shown in fig. 3. I.e., each slave node actually receives multiple wavelength references, an adaptive wavelength reference is obtained using active filtering techniques. In this implementation, a local laser may be tuned to a position near a reference wavelength by an injection locking technique IL, and due to a frequency pulling effect, the local laser excites an optical signal having the same frequency and phase as the wavelength reference, and the optical signal is used as final carrier loading data.

Illustratively, in the automatic wavelength tracking locking module of the slave node, external light (filtering) is injected into a distributed feedback laser (DFB) through a 1 port and a 2 port of a circulator, and the DFB determines a wavelength corresponding to an input optical line from the DFB and sends the wavelength to the 2 port. Then, the port 2 inputs the optical signal with the wavelength into the port 3, and the output optical signal is fed back to the DFB after being transmitted and processed by a photo-diode (PD), a detector, a microprocessor and a driver, thereby completing the generation of the optical carrier with the same frequency.

In the implementation mode, each slave node and the master node ensure stable frequency difference, and the whole network wavelength synchronization can be realized. In addition, each slave node adopts the automatic locking and tracking technology of the wavelength reference, so that the optical network system has self-adaptability. This means that the small-range adjustment of the wavelength of the injected light source does not affect the synchronous operation between the two light sources, so that the performance damage of the system caused by the uncertain drift of the laser wavelength due to environmental changes can be avoided.

However, since the operating wavelength references of the different network slave nodes are fixed, a wide range of tunability of the operating wavelength cannot be achieved. In addition, in this implementation, the working bandwidth of each network node must be smaller than the spectral line interval of the optical frequency comb OFC, so that a large working bandwidth cannot be allocated to any network node, thereby limiting the flexibility of spectrum allocation in the elastic optical network. Moreover, in the current scheme, the working wavelength of each network node is generated at the master node in a unified manner and then is sent to each branch node, which cannot be flexibly adjusted, and cannot realize flexible spectrum allocation. Finally, the technology is only suitable for networks with tree topology structures, but not suitable for networks with other topology structures, so that the technology has certain limitation.

In summary, it is considered that future networks need to develop towards flexible optical networks and flexible spectrum allocation, and lasers of each network node are independent from each other, and random frequency differences up to gigahertz (GHz) level are easily generated, so that limitations are brought to the development of network flexibility and spectrum utilization efficiency.

In view of this, the present application provides a method for calibrating a wavelength of a whole network, which employs a working mechanism that all nodes of the whole network calibrate an optical frequency based on a uniform wavelength reference. Even if the wavelength of the laser generates jitter drift, each network node can lock and track the network wavelength reference, so that the wavelength of each network node always has stable frequency difference and phase difference. Reference light is acquired, reference light is generated according to the reference light, and then a first target light signal with stable frequency difference with the reference light is generated and used for loading data during self work. The method is suitable for each network node of the system, adopts the uniform wavelength reference to carry out wavelength calibration, and can ensure that the optical network nodes have stable frequency error, so that the network reduces the protection band gap when adopting flexible grid deployment, improves the utilization efficiency of the network frequency spectrum, and further ensures the signal transmission quality. Meanwhile, the design of the device for realizing optical frequency calibration in each network node is provided, and the device comprises a frequency calibration unit, a frequency expansion unit and a frequency selection unit, so that the aim of the whole network optical wavelength synchronization is realized, and each node can flexibly generate the working wavelength of the node.

The wavelength calibration method provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Fig. 4 is a schematic diagram illustrating an example of a full-network wavelength calibration method to which the present invention is applied. The specific implementation step 400 includes:

and S410, acquiring a reference optical signal.

The form of the reference optical signal includes one of direct current continuous light, low-speed intensity modulation continuous light and low-order coherent modulation continuous light.

It should be appreciated that the reference optical signal is more diversified in form, and low-speed intensity modulated continuous light and low-order coherent modulated continuous light for loading the data signal are added.

Illustratively, acquiring the reference optical signal includes: receiving a first signal, wherein the first signal is a light signal received by a current network node from a network node before the current network node; the reference optical signal is filtered and extracted from the first signal.

It should be understood that the wavelength calibration method of the present application is mainly directed to a mechanism for performing full-network wavelength synchronization between network nodes in one transmission direction with reference to the wavelength of the same reference optical signal. Therefore, the entire transmission process in which the current network node receives a signal from a network node previous to the current network node and sends a signal to a network node subsequent to the current network node after acquiring the first target optical signal is unidirectional. That is, for the current network node, one pair of transceiving interfaces corresponds to one transmission direction.

It should be noted that the sources of the reference optical signals in the current network nodes in different application scenarios are different. For the reference optical signal in the tree topology, the reference optical signal mainly comes from a signal transmitted by a previous node. For example, a downstream signal transmitted from the optical line terminal OLT to the optical network unit ONU in the wavelength division multiplexing passive optical network WDM-PON, a signal transmitted from the root node to the leaf node in the data center DC, and the like. For a reference optical signal in a ring topology, the signal mainly comes from the previous node. This is not a particular limitation of the present application.

And S420, adjusting the output wavelength of the local laser according to the reference optical signal to generate a reference optical signal.

Wherein the reference optical signal has the same wavelength as the reference optical signal, and the reference optical signal may have a wavelength λ ₀ Of the optical signal.

It should be noted that the reference optical signal and the reference optical signal have the same wavelength. In order to ensure the current network Node due to signal distortion or path loss difference _X The medium wavelength calibration and the signal transmission quality need to adjust the wavelength of the local laser according to the reference light, so as to obtain the reference light with higher signal quality, thereby realizing the subsequent wavelength calibration mechanism. In one possible implementation, when the reference optical signal is in the form of direct-current continuous light, the output wavelength of the local laser is adjusted according to a wavelength locking technique or an injection locking technique to generate the reference optical signal.

For example, the current network node filters and extracts a reference optical signal from the received signal by using a Fiber Bragg Grating (FBG) that satisfies a wavelength matching condition. That is, the reference optical signal goes through the reflection path, and the rest spectrum is transmitted through the FBG for demodulation or continuous transmission. Since the injection locking technique can amplify the injected wavelength while suppressing other sidebands, it is equivalent to active very narrow bandwidth filtering. In another possible implementation, when the reference optical signal is in the form of low-speed intensity modulated continuous light, the reference optical signal is coupled with an output optical signal input coupler of the local laser; inputting the coupled optical signals into a balance detector to obtain a phase difference; and adjusting the optical frequency of the local laser according to the phase difference feedback to generate a reference optical signal.

In this implementation, for the case that the reference light is in the form of low-speed intensity modulated continuous light, a coupler and balanced detection are adopted to obtain a phase difference, and then a reference light signal is generated. This implementation enables frequency calibration with reference light modulation data. This makes some low-speed control signaling can pass through reference light signal transmission, has improved the utilization ratio of resource. In another possible implementation manner, when the reference optical signal is in the form of low-order coherent modulated continuous light, the reference optical signal and the output optical signal of the local laser are input into a 90 ° optical mixer to obtain an in-phase component and a quadrature component of the optical signal; determining a phase difference of the optical signal according to the in-phase component and the quadrature component of the optical signal; and adjusting the optical frequency of the local laser according to the phase difference feedback of the optical signal to generate a reference optical signal.

In this implementation, for the case where the reference light is in the form of low-order coherent modulated continuous light, a 90 ° optical mixer is employed to obtain an in-phase component and a quadrature component, and determine a phase difference of the optical signals, thereby generating the reference optical signal. The implementation is carried out at a reference light lambda ₀ The data is modulated, the utilization rate of resources is improved, and compared with an intensity modulation mode, the method can realize the transmission of signaling data with higher speed and improve the transmission quality of the signaling data. In yet another possible implementation, the reference optical signal is in the form of a reference optical signalDouble light waves with respective wavelengths of λ ₀ And λ ₀ + Δ f, the method further comprising: according to wavelength of λ ₀ Adjusts the output wavelength of the first local laser to generate a reference optical signal having a wavelength λ ₀ The reference optical signal of (a); according to wavelength of λ ₀ The + Δ f reference optical signal adjusts the output wavelength of the second local laser to generate a reference optical signal having a wavelength λ ₀ Optical signal of + Δ f, the second local laser outputting wavelength λ ₀ The optical signal of + Δ f has a wavelength λ corresponding to the output of the first local laser ₀ A part of the optical signal of the reference light is beat-frequency to obtain an electrical signal with a frequency Δ f.

S430, a plurality of target optical signals are generated based on the reference optical signal.

The wavelength of each of the plurality of target optical signals is different, and the frequency difference between each of the target optical signals and the reference optical signal is different and fixed.

One possible implementation is to generate multiple target optical signals based on a reference optical signal by an optical frequency comb OFC technique.

S440, extracting a first target optical signal from the plurality of target optical signals for data transmission.

Wherein the first target optical signal has a wavelength λ _x The direct current continuous optical signal of (1).

One possible implementation, which extracts a first target optical signal from a plurality of target optical signals, includes: the plurality of target optical signals are extracted from the optical frequency comb into a first target optical signal according to an injection-locked IL technique or a tunable optical filter cascade optical amplifier technique.

Illustratively, the first target optical signal is extracted from the broadband optical comb using an injection locking technique. The method specifically comprises the following steps: the wide-spectrum optical comb is injected into the local laser through the port of the circulator, and the wavelength of the local laser is adjusted to be within a locking range by the MCU. Due to the principle of injection locking technology, the laser finally generates a standard first target optical signal, which is output through the circulator port. And finally, modulating data by using the first target optical signal as a carrier. The operating wavelength of each network node can be flexibly selected by adjusting the target optical signal.

By way of example and not limitation, based on the above implementation, the current network node loads data on the first target optical signal, and couples the data with the reference optical signal and the second signal, and then sends the data to the next network node, where the second signal is an optical signal directly transmitted to the next network node in the first signal.

Illustratively, the wavelength division multiplexed signal received by the current network node from the previous node includes three parts, one part is a signal to be resolved locally, one part is a signal to be transmitted to the next network node, and the other part is a reference optical signal for the optical frequency reference of the present application. The current network node, after acquiring the optical frequency reference, uses a frequency calibration device to generate the wavelength of its own transmitted data, i.e. the first target optical signal. After the first target signal modulates the data, the data is combined with the wavelength reference signal and other signals transmitted to the next network node, and the signals are sent to the next network node.

The technical scheme of the application is applied to the elastic optical network, such as a multi-level ring network structure. After the wavelength calibration is carried out on the whole network, the frequency spectrum interval of the laser wavelength among all network nodes is stable, so that the frequency spectrum aliasing caused by the random frequency difference of the laser is avoided, the guard band interval among the frequency spectrums can be cancelled, and the frequency spectrum utilization rate is improved. Compared with the traditional optical network, the all-optical network has stronger flexibility, transparency, compatibility and expansibility. In addition, under the condition of ensuring wavelength synchronization, the signal at each network node is added and dropped, and the sub-band level optical switching can also be flexibly realized.

Fig. 5 is a schematic diagram illustrating an example of an operation principle of implementing wavelength calibration in a network node to which the present application is applied. Assuming that the whole network uniformly adopts lambda ₀ As a wavelength reference, each network node obtains a low-quality optical signal λ from the received wavelength division multiplexed signal WDM ₀ Generating a frequency reference light lambda corresponding to a high quality by a frequency calibration unit ₀ Then generating reference light λ with high quality by a frequency spreading unit ₀ Target optical carrier lambda with stable frequency difference _x 。

As shown in fig. 5, the network Node x receives a wavelength division multiplexed signal from a previous Node. The wavelength division multiplexed signal comprises three parts, one part needs to be resolved at local Rx, one part needs to be passed through to the next network node, and the other part is used for optical frequency reference.

Specifically, node x is obtaining the optical frequency reference λ of low quality ₀ Thereafter, the wavelength λ of the local laser is controlled ₀ ' Generation of high-quality reference light λ within a lockable range using a frequency calibration device ₀ . Subsequent determination of the wavelength lambda for the data transmitted by itself by means of the frequency spreading unit and the frequency selection unit _x I.e. the target optical carrier lambda _x . Modulated by data and then compared with a wavelength reference signal lambda ₀ And other signals transmitted to the next network node are combined and then sent to the next network node. In this implementation, the transfer of the wavelength reference is done, and λ _x And λ ₀ The stable frequency difference of the wavelength reference is fixed. Along with the transmission of optical signals, all network nodes carry out frequency calibration, and finally, the wavelength synchronization of the whole network is realized.

It should be noted that the light signal sources are different in different application scenarios. For tree topology, optical signal λ ₀ Derived from transmission by a preceding nodeA signal. For example, a downstream signal transmitted from the optical line terminal OLT to the optical network unit ONU in the wavelength division multiplexing passive optical network WDM-PON, a signal transmitted from the root node to the leaf node in the data center DC, and the like. For ring topology, optical signal λ ₀ A signal originating from a previous node. In addition, the optical signal λ ₀ Can take a variety of forms, including: at least one of continuous light, low-speed intensity modulated light, and low-order coherent modulated light.

Fig. 6 is a schematic diagram showing an example of the operation principle of the wavelength calibration device to which the present invention is applied. As shown in fig. 6, the device mainly comprises three parts, namely a frequency calibration unit, a frequency spreading unit and a frequency selection unit.

Wherein the frequency calibration unit is used for calibrating the frequency according to the reference light lambda ₀ Signal conditioning of the output wavelength lambda of the local laser ₀ ' to generate high quality reference light, which means wavelength λ ₀ Of the optical signal.

It should be noted that the device structure of the frequency calibration unit needs to be based on the reference light λ ₀ Is adapted. Exemplarily, at reference light λ ₀ In the case of direct current continuous light, a wavelength locking technique or an injection locking technique is employed. At reference light lambda ₀ In the case of low-order coherent modulated light, the laser frequency needs to be adjusted by extracting phase difference feedback, so as to realize optical frequency calibration, such as an optical phase-locked loop scheme.

The function of the frequency spreading unit is based on the reference light lambda ₀ Expanding the frequency of the light to generate a plurality of reference lights lambda ₀ Optical signal lambda with stable frequency difference _x . Illustratively, this can be achieved by the technique of optical frequency combing. First, each spectral line has a fixed frequency difference from the reference light. Secondly, a large frequency difference can be obtained through the optical frequency combing technology, so that the optical network system can work in a large wavelength range. Meanwhile, the technology can also realize the adjustability of the frequency of small particles and the integration miniaturization. For example, there are currently technologies that generate optical frequency combs on-chip (e.g., semiconductor mode-locked lasers, nonlinear photonic chips, etc.).

The frequency selection unit has the functions ofTarget optical carrier lambda _x Filtered and amplified from the optical-frequency comb as a carrier wave of transmission data. In the embodiment of the present application, an injection locking technique IL may be used, and a technique of a tunable optical filter and an optical amplifier may also be used.

It should be appreciated that the tunable function of the frequency selection unit may ensure that each network node flexibly generates an adaptive operating wavelength.

Fig. 7 is a schematic diagram of an example of an optical frequency calibration apparatus to which the present invention is applied. As shown in fig. 7, the reference light λ ₀ In the form of a direct current continuous light, inserted in the received wavelength division multiplexed WDM spectrum. Among them, the direct current continuous light form is the easiest to extract the wavelength reference.

Specifically, the WDM spectrum is filtered to extract the reference light λ after passing through an Optical Band Pass Filter (OBPF) ₀ . In the embodiment of the present application, a Fiber Bragg Grating (FBG) that satisfies a wavelength matching condition is used to realize this function. I.e. the reference light lambda ₀ The reflected path is followed, and the rest spectrum is transmitted through the FBG for demodulation or continuous transmission.

In the frequency calibration unit, the received reference light λ ₀ Injecting the light into the local laser through the 1 port and the 2 port of the circulator so that the wavelength of the output optical signal of the local laser is equal to the reference light lambda ₀ Are close in wavelength. The local laser will then modulate the optical signal, i.e. the reference light λ of high quality ₀ Input into the 3 ports. At this time, the reference light is divided into two by 3 ports. One part provides a feedback signal, and a Micro Controller Unit (MCU) controls the wavelength lambda of the local laser through a frequency difference capture circuit ₀ ' is in a lockable range. The injection locking technique IL can amplify the injected wavelength while suppressing other sidebands, which is equivalent to active very narrow bandwidth filtering. The other part is output to the frequency spreading unit. In this implementation, high quality reference light λ output by 3 ports ₀ With reference light lambda ₀ Are of the same frequency. In addition, because the device has a tracking function, the frequency can be realized under the condition that the reference light can be ensured to driftAnd (6) calibrating.

In the frequency spreading unit, reference light λ is transmitted ₀ A low V pi optical Phase Modulator (PM) is injected and driven with a sinusoidal signal. In order to ensure that the frequencies of different network nodes are consistent, it is necessary to extract a clock frequency from received data by Clock Data Recovery (CDR), and then perform frequency conversion to generate a corresponding sine wave signal. According to the principle of the optical phase modulator, when the peak-to-peak value of the injected sinusoidal signal is large, the optical phase modulator outputs a plurality of spectral lines, and the intervals of the spectral lines are sinusoidal wave frequencies, namely the intervals of the optical frequency combs. When the output of the optical phase modulator is injected into the nonlinear photonic chip, the photonic chip realizes ultra-wide frequency expansion based on the four-wave mixing effect. Multiple and reference lights lambda generated in frequency spreading unit ₀ The optical carrier having a fixed frequency difference includes a target optical carrier lambda _x . Wherein, the phases of each spectral line are mutually locked and have stable frequency difference.

In the frequency selection unit, the injection locking technology is adopted to extract a target optical signal lambda from a wide-spectrum optical frequency comb _x . The specific process is that the wide-spectrum optical frequency comb is injected into the local laser through a port 1 and a port 2 of the circulator, and the wavelength of the local laser is adjusted to lambda by the MCU _x ' at (in lock range), the laser ultimately produces a standard λ due to the principles of injection locking technology _x And light is output through a port of the circulator 3. Finally by λ _x As a carrier, data is modulated. Here by adjusting λ _x And the working wavelength of each network node is flexibly selected.

In summary, in this implementation manner, the optical frequency calibration apparatus can achieve the goal of wavelength calibration, and meanwhile, it is ensured that each node can flexibly generate its own working wavelength. At the same time, the wavelength allocation of the optical network system has more flexibility.

Fig. 8 is another exemplary view of a light frequency calibration unit to which the present application is applied. Unlike the optical frequency calibration apparatus shown in fig. 7, the reference light λ of this implementation is ₀ A low speed data signal may be loaded.

When the intensity modulation is used to load data, the frequency calibration part adopts the structure shown in fig. 8, and the principle is the same as that of the balanced phase-locked loop.

First, reference light λ is passed through an optical bandpass filter ₀ The signal is filtered out. Then, the wavelength of the local laser is adjusted to λ ₀ Nearby, corresponds to a local oscillator. And, the reference light λ ₀ And the coupled optical signal enters a balance detector to carry out signal detection. Because the intensity modulation signal itself contains a large carrier capacity, the output signal of the balanced detector contains a phase difference generated after coherent reception of the signal carrier and the local oscillator. The phase difference is fed back to the local oscillator laser through a loop filter (loop filter), so that optical carrier synchronization is realized, that is, the wavelength of the local laser and the reference wavelength are synchronized. Meanwhile, the output signal of the balance detector can be recovered after further demodulation.

Alternatively, in this implementation, the frequency spreading unit and the frequency selecting unit in the wavelength calibration device may use the same structure as fig. 7, and this application is not limited in this respect.

In summary, in this implementation, the apparatus is capable of frequency calibration with reference light modulation data. This allows some low speed control signaling to pass through λ ₀ And the resource utilization rate is improved.

Fig. 9 is a further exemplary view of a light frequency calibration unit to which the present application is applied. Unlike the optical frequency calibration apparatus shown in fig. 7, the reference light λ of this implementation is ₀ A low speed data signal may be loaded. Based on reference light lambda ₀ And the data is modulated, so that the utilization rate of resources can be further improved. Compared with the intensity modulation mode adopted in fig. 8, the implementation mode adopts a low-order coherent modulation mode, so that signaling data transmission with higher speed can be realized, and the transmission quality of the signaling data is improved.

When the data is loaded by using the low-order coherent modulation, the frequency calibration part adopts the structure shown in fig. 9, and the principle of the frequency calibration part is the same as that of the costas phase-locked loop.

First, a reference light λ is passed through an optical bandpass filter ₀ The signal is filtered out. Then, the wavelength of the local laser is adjusted to λ ₀ Nearby, corresponds to a local oscillator. And, the reference light λ ₀ And the output optical signal of the local laser are input into a 90-degree optical mixer together. Wherein, the

output ports

1 and 2 of the optical mixer enter into the balanced receiver 1, and the in-phase component of the signal is obtained. The 3 and 4 output ports of the optical mixer enter the balanced receiver 2, resulting in the quadrature component of the signal. The frequency difference is extracted by frequency difference acquisition circuitry based on the in-phase and quadrature components of the signal. The frequency difference is passed through a voltage controlled oscillator and fed back to a phase modulator to adjust the phase of the local laser. After the optical network system is stabilized, the local laser outputs the reference light lambda ₀ The data demodulation is also completed by the local oscillation optical signals with the same frequency.

It should be noted that the output optical signal of the local laser will split a part of λ ₀ As reference light, for use in subsequent frequency-spreading modules.

In order to achieve high-quality error extraction, a low-order coherent modulation mode such as Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK) may be adopted in the embodiment of the present application.

In summary, in this implementation manner, the optical frequency calibration apparatus can implement signaling data transmission at a higher rate, and improve the transmission quality of the signaling data.

Fig. 10 is a schematic diagram of an example of an optical frequency selecting unit to which the present invention is applied. As shown in fig. 10, in the frequency selective unit, the function of frequency selection can be realized by a technique of cascading optical amplifiers through optical filters.

Illustratively, first, a tunable optical filter is used to filter out a desired target optical carrier λ from a frequency comb _x . Then, the optical amplifier is used againIncreasing optical power and outputting target optical carrier lambda _x . Finally, the target optical carrier λ _x The optical signal enters an optical module and is modulated by an optical modulator.

Alternatively, in this implementation, the frequency spreading unit in the wavelength calibration device may use the same structure as that of fig. 6. The frequency calibration unit can be used in the same configuration as in fig. 7 (direct current continuous light), fig. 8 (low-speed intensity modulated light), and fig. 9 (low-order coherent modulated light), respectively, depending on the form of the reference light. This is not a particular limitation of the present application.

Fig. 11 is a further explanatory view of the optical frequency calibration apparatus to which the present application is applied. Unlike the optical frequency calibration apparatus provided in fig. 7 to 10, the reference light is in the form of dual light waves having wavelengths λ ₀ And λ ₀ + Δ f. I.e. two spectral lines are input, the frequency interval of the two spectral lines is Δ f, and the two spectral lines are used for generating a reference input radio frequency signal of the optical frequency comb, i.e. the frequency difference between two adjacent spectral lines in the optical frequency comb. This implementation can ensure that the electrical clocks of each network node are synchronized.

In particular, as shown in fig. 11, each network node filters out two reference spectral lines, i.e. λ, from the received WDM signal by using an optical bandpass filter OBPF ₀ And λ ₀ + Δ f. Since the two reference optical lines do not differ much in frequency, they can pass through the OBPF at the same time. Then, the two reference spectral line signals are divided into two parts by an optical power splitter and respectively injected into the two sets of frequency calibration devices. In this case, the input to the frequency calibration device is two spectral lines, each corresponding to λ ₀ And λ ₀ + Δ f. And respectively tracking the two spectral lines by adopting active filtering injection locking. Wherein, in the frequency calibration device 1, the wavelength is λ ₀ Adjusts the output wavelength of the local laser 1, i.e. tunes the optical frequency of the local laser to lambda ₀ To (3). In the frequency calibration device 2, λ is the wavelength ₀ The reference light of + Δ f adjusts the output wavelength of the local laser 2, i.e. the optical frequency of the local laser 2 is tuned to λ ₀ At + Δ f. The specific frequency calibration process may refer to the implementation shown in fig. 7, in order toFor brevity, no further description is provided herein. In summary, the reference light λ can be generated by the frequency calibration device 1 ₀ Common-frequency high-quality reference optical signal lambda ₀ The reference light lambda can be generated by the frequency calibration means 2 ₀ High-quality reference optical signal lambda with same frequency of + delta f ₀ +Δf。

This implementation is equivalent to active filtering, while suppressing phase noise generated by the reference light during transmission. Output optical signal lambda of the frequency calibration device 1 ₀ The optical power splitter is divided into two parts, one part is used as beat frequency, and the other part is used as the input of the phase modulator. Output optical signal lambda of the frequency calibration means 2 ₀ + Δ f and λ ₀ After coupling through the coupler, a photodetector (e.g., a photodiode) is input. I.e. the wavelength of the local laser 2 output is lambda ₀ The optical signal of + deltaf is used to match the local laser 1 output at a wavelength lambda ₀ A part of the optical signal of the reference light is beat-frequency to obtain an electrical signal with a frequency Δ f. According to the square law detection principle, the electrical signal output by the photodetector is just a sine wave signal with a frequency Δ f. After the sine wave signal is input into the phase modulator PM, seed light of the optical frequency comb is generated, and finally, the wider optical frequency comb is realized by using the nonlinear photonic chip.

The arrangement shown in figure 11 provides a reference for the frequency of the electrical signal, while providing a wavelength reference. Compared with the method for recovering the clock from the data and further extracting the wavelength reference shown in fig. 7, the circuit part structure of the implementation mode is simpler.

In summary, the present application provides a method and an apparatus for calibrating a wavelength of a whole network, which can improve spectrum utilization efficiency and network flexibility. Specifically, the method is realized by combining units in a frequency calibration device: namely, the frequency calibration unit generates high-quality reference light based on the reference light by using the techniques of frequency locking, phase locking and the like, and can be adapted to various forms of the reference light. The frequency expansion unit realizes high-precision frequency expansion of the reference light by utilizing the phase locking relation of each spectral line in the optical frequency comb. The frequency selection unit has tunability, so that each network node can flexibly generate the self-adaptive working wavelength.

According to the method and the device for calibrating the wavelength of the whole network, the unified wavelength reference is adopted, so that the wavelength synchronization of the whole network is ensured, and the frequency spectrum utilization efficiency and the network flexibility are improved. From the aspect of transmission performance, the aliasing of frequency spectrums among signals can be avoided, and the signal transmission quality is improved. From the aspect of network resource allocation, flexible allocation of small-granularity spectrum resources can be realized, so that guard bands are reduced, system allowance is further released, and spectrum utilization rate is improved. From the aspect of hardware deployment, the colorless can be realized, and the wavelength of each node is continuously adjustable and flexibly configured.

The wavelength calibration method side embodiment of the present application is described in detail above with reference to fig. 1 to 11, and the device side embodiment of the wavelength calibration of the present application will be described in detail below with reference to fig. 12 and 13. It is to be understood that the description of the apparatus embodiments corresponds to the description of the method embodiments. Therefore, reference may be made to the preceding method embodiments for portions that are not described in detail.

Fig. 12 is a schematic block diagram of a wavelength calibration device provided in an embodiment of the present application. As shown in fig. 12, the apparatus 1000 may include a processing unit 1100, a transceiver unit 1200, a frequency calibration unit 1300, a frequency spreading unit 1400, and a frequency selection unit 1500.

It is to be understood that the apparatus 1000 may include means for performing the method of method 400 in fig. 4. Also, the units and other operations and/or functions described above in the apparatus 1000 are respectively for realizing the corresponding flow of the method 400 in fig. 4.

Exemplarily, the processing unit is configured to acquire a reference light signal;

the frequency calibration unit is used for adjusting the output wavelength of the local laser according to the reference optical signal to generate a reference optical signal, and the wavelength of the reference optical signal is the same as that of the reference optical signal;

a frequency spreading unit for generating a plurality of target optical signals based on the reference optical signal, each of the plurality of target optical signals having a different wavelength, and each of the target optical signals having a different and fixed frequency difference from the reference optical signal;

and the frequency selection unit is used for extracting the first target optical signal from the plurality of target optical signals so as to carry out data transmission.

Optionally, the transceiver unit is configured to receive a first signal, where the first signal is an optical signal received by the current network node from a network node previous to the current network node;

and the processing unit is also used for filtering and extracting the reference light signal from the first signal.

It is also understood that the transceiving unit 1200 in the apparatus 1000 may be implemented by a transceiver, and the processing unit 1100 in the apparatus 1000 may be implemented by at least one processor.

It is further understood that the transceiving unit 1200 in the apparatus 1000 may be implemented by an input/output interface, a circuit, etc., and the processing unit 1100 in the apparatus 1000 may be implemented by a processor, a microprocessor, an integrated circuit, etc., integrated on the chip or the chip system.

Fig. 13 is another schematic block diagram of a tracking compensation apparatus 2000 provided in an embodiment of the present application. As shown in fig. 13, the apparatus 2000 includes a processor 2010, a transceiver 2020, and a memory 2030. Wherein the processor 2010, the transceiver 2020, and the memory 2030 are in communication with each other via the internal connection path, the memory 2030 is configured to store instructions, and the processor 2010 is configured to execute the instructions stored in the memory 2030 to control the transceiver 2020 to transmit and/or receive signals.

It is to be understood that the apparatus 2000 may be adapted to perform the various steps and/or processes of the above-described method embodiments.

Alternatively, the memory 2030 may include a read-only memory and a random access memory, and provide instructions and data to the processor. The portion of memory may also include non-volatile random access memory. The memory 2030 may be a separate device or may be integrated into the processor 2010. The processor 2010 may be configured to execute instructions stored in the memory 2030, and when the processor 2010 executes instructions stored in the memory, the processor 2010 is configured to perform the various steps and/or flows of the above-described method embodiments.

The transceiver 2020 may include a transmitter and a receiver, among others. The processor 2010 and the memory 2030 and the transceiver 2020 may be devices integrated on different chips. For example, the processor 2010 and the memory 2030 may be integrated within a baseband chip and the transceiver 2020 may be integrated within a radio frequency chip. The processor 2010 and the memory 2030 and the transceiver 2020 may also be integrated devices on the same chip. This is not a limitation of the present application.

The transceiver 2020 may also be a communication interface, such as an input/output interface, a circuit, or the like. The transceiver 2020 may be integrated with the processor 2010 and the memory 2020 on the same chip, such as a baseband chip.

It should be understood that the specific examples in the embodiments of the present application are only for helping those skilled in the art to better understand the technical solutions of the present application, and the above specific implementation can be considered as the best implementation of the present application, and not for limiting the scope of the embodiments of the present application.

It should also be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

It should be understood that, in the above embodiments, the wavelength calibration method flow provided by the present application is only illustrated, and the protection scope of the present application is not limited in any way.

It is also to be understood that the terminology and/or descriptions herein may be consistent between different embodiments and may be mutually inconsistent, if not expressly stated or logically conflicting, and that features of different embodiments may be combined to form new embodiments based on their inherent logical relationships. It should be understood that in the embodiments of the present application, the processor may be a Central Processing Unit (CPU), and the processor may also be other general-purpose processors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs) or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general purpose processor may be a microprocessor, any conventional processor, etc.

It will also be appreciated that the memory in the embodiments of the subject application can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. The non-volatile memory may be a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an electrically Erasable EPROM (EEPROM), or a flash memory. Volatile memory can be Random Access Memory (RAM), which acts as external cache memory. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), synchronous Dynamic Random Access Memory (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct bus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

The method steps in the embodiments of the present application may be implemented by hardware, or may be implemented by software instructions executed by a processor. The software instructions may be comprised of corresponding software modules that may be stored in random access memory, flash memory, read only memory, programmable read only memory, erasable programmable read only memory, electrically erasable programmable read only memory, registers, a hard disk, a removable hard disk, a CD-ROM, or any other form of storage medium known in the art. Illustratively, a storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. Of course, the storage medium may also be integral to the processor. The processor and the storage medium may reside in an ASIC. Additionally, the ASIC may reside in a network node. Of course, the processor and the storage medium may reside as discrete components in a network node.

In the above embodiments, all or part of the implementation may be realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are performed in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, a network appliance, a user device, or other programmable apparatus. The computer program or instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer program or instructions may be transmitted from one website, computer, server or data center to another website, computer, server or data center by wire or wirelessly. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that integrates one or more available media. The usable medium may be a magnetic medium, such as a floppy disk, a hard disk, a magnetic tape; optical media such as digital video disks; but also semiconductor media such as solid state disks. The computer readable storage medium may be volatile or nonvolatile storage medium, or may include both volatile and nonvolatile types of storage media.

It should be understood that in the above embodiments, the embodiments may be independent solutions or may be combined according to the inherent logic, and the solutions all fall into the protection scope of the present application. The network node may perform some or all of the steps in various embodiments. These steps or operations are merely examples, and other operations or variations of various operations may be performed herein. Further, the various steps may be performed in a different order presented in the embodiments, and not all of the operations in the embodiments of the application may be performed.

It is to be understood that the various numerical references referred to in the embodiments of the present application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of the present application. The sequence numbers of the above processes do not mean the sequence of execution, and the execution sequence of each process should be determined by its function and inherent logic, and should not limit the implementation process of the embodiment of the present application.

As used in this specification, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between 2 or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from two components interacting with each other with a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a U disk, a removable hard disk, a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of wavelength calibration, the method comprising:

acquiring a reference optical signal;

adjusting the output wavelength of a local laser according to the reference optical signal to generate a reference optical signal, wherein the wavelength of the reference optical signal is the same as that of the reference optical signal;

generating a plurality of target optical signals based on the reference optical signal, each of the plurality of target optical signals having a different wavelength, a different and fixed frequency difference from the reference optical signal;

and extracting a first target optical signal from the plurality of target optical signals for data transmission.

2. The method of claim 1, wherein the acquiring the reference optical signal comprises:

receiving a first signal, wherein the first signal is a light signal received by a current network node from a network node previous to the current network node;

and filtering and extracting the reference light signal from the first signal.

3. The method of claim 1 or 2, wherein the reference optical signal comprises one of a dc continuous light, a low-speed intensity modulated continuous light, and a low-order coherent modulated continuous light.

4. The method of claim 3, wherein adjusting the output wavelength of the local laser based on the reference optical signal to generate the reference optical signal comprises:

when the reference optical signal is in the form of the direct-current continuous light, adjusting an output wavelength of the local laser according to a wavelength locking technique or an injection locking technique to generate a reference optical signal.

5. The method of claim 3, wherein adjusting the output wavelength of the local laser based on the reference optical signal to generate the reference optical signal comprises:

coupling the reference optical signal with an output optical signal input coupler of the local laser when the reference optical signal is in the form of the low-speed intensity modulated continuous light;

inputting the coupled optical signals into a balance detector to obtain a phase difference;

and adjusting the optical frequency of the local laser according to the phase difference feedback to generate the reference optical signal.

6. The method of claim 3, wherein adjusting the output wavelength of the local laser based on the reference optical signal to generate the reference optical signal comprises:

when the reference optical signal is in the form of the low-order coherent modulation continuous light, inputting the reference optical signal and an output optical signal of the local laser into a 90-degree optical mixer to obtain an in-phase component and a quadrature component of an optical signal;

determining a phase difference of the optical signal according to an in-phase component and a quadrature component of the optical signal;

and adjusting the optical frequency of the local laser according to the phase difference feedback of the optical signal to generate the reference optical signal.

7. The method according to any one of claims 1 to 6, wherein when the reference light signal is in the form of a dual light wave, the dual light waves each have a wavelength λ ₀ And λ ₀ + Δ f, the method further comprising:

according to wavelength of λ ₀ Adjusts the output wavelength of the first local laser to generate a reference optical signal having a wavelength λ ₀ The reference optical signal of (a);

according to wavelength of λ ₀ The + Δ f reference optical signal adjusts the output wavelength of the second local laser to generate a reference optical signal having a wavelength λ ₀ An optical signal of + Δ f, wherein the second local laser outputs at a wavelength λ ₀ An optical signal of + Δ f is used at a wavelength λ with the output of the first local laser ₀ A part of the optical signal of the reference light is beat-frequency to obtain an electrical signal with a frequency Δ f.

8. The method according to any one of claims 1 to 7, further comprising:

and loading data on the first target optical signal, coupling the first target optical signal with the reference optical signal and a second signal, and sending the first target optical signal to a next network node, wherein the second signal is an optical signal directly transmitted to the next network node in the first signal.

9. A wavelength calibration device, comprising:

a processing unit for acquiring a reference light signal;

the frequency calibration unit is used for adjusting the output wavelength of a local laser according to the reference optical signal to generate a reference optical signal, and the wavelength of the reference optical signal is the same as that of the reference optical signal;

a frequency spreading unit configured to generate a plurality of target optical signals based on the reference optical signal, each of the plurality of target optical signals having a different wavelength, and a frequency difference between each of the target optical signals and the reference optical signal being different and fixed;

and the frequency selection unit is used for extracting a first target optical signal from the plurality of target optical signals so as to carry out data transmission.

10. The apparatus of claim 9, further comprising:

a transceiver unit, configured to receive a first signal, where the first signal is a light signal received by a current network node from a network node previous to the current network node;

the processing unit is further configured to filter and extract the reference light signal from the first signal.

11. The apparatus of claim 9 or 10, wherein the reference optical signal comprises one of a dc continuous light, a low-speed intensity modulated continuous light, and a low-order coherent modulated continuous light.

12. The apparatus of claim 11, wherein when the reference light signal is in the form of the DC continuous light,

the frequency calibration unit is further configured to adjust an output wavelength of the local laser according to a wavelength locking technique or an injection locking technique to generate a reference optical signal.

13. The method of claim 11, wherein when the reference light signal is in the form of the low-speed intensity modulated continuous light,

the frequency calibration unit is further configured to couple the reference optical signal with an output optical signal input coupler of the local laser;

14. The apparatus of claim 11 wherein when the reference optical signal is in the form of the low order coherently modulated continuous light,

the frequency calibration unit is further configured to input the reference optical signal and the output optical signal of the local laser into a 90 ° optical mixer to obtain an in-phase component and a quadrature component of the optical signal;

15. The apparatus according to any one of claims 9 to 14, wherein when the reference light signal is in the form of dual light waves, the dual light waves have respective wavelengths λ ₀ And λ ₀ +Δf，

The frequency calibration unit is also used for calibrating the frequency according to the wavelength of lambda ₀ Adjusts the output wavelength of the first local laser to generate a reference optical signal having a wavelength λ ₀ The reference optical signal of (a);

the frequency calibration unit is also used for calibrating the frequency according to the wavelength of lambda ₀ The + Δ f reference optical signal adjusts the output wavelength of the second local laser to generate a reference optical signal having a wavelength λ ₀ An optical signal of + Δ f, wherein the second local laser outputs at a wavelength λ ₀ An optical signal of + Δ f is used at a wavelength λ with the output of the first local laser ₀ A part of the optical signal of the reference light is beat-frequency to obtain an electrical signal with a frequency Δ f.

16. The apparatus according to any one of claims 9 to 15,

the transceiver unit is further configured to load data on the first target optical signal through the processing unit, couple the first target optical signal with the reference optical signal and a second signal, and send the first target optical signal to a subsequent network node, where the second signal is an optical signal directly transmitted to the subsequent network node from the first signal.

17. A communications apparatus, comprising: a processor and interface circuitry for receiving and transmitting signals to or from a communication device other than the communication device, the processor implementing the method of any of claims 1 to 8 for the communication device by logic circuitry or executing code instructions.

18. A resilient optical network system, characterized in that the resilient optical network comprises a first network node comprising a communication apparatus according to any of claims 9 to 16 or 17.

19. A chip, comprising: a processor for calling and running a computer program from a memory so that the chip is installed to perform the method of any one of claims 1 to 8.

20. A computer storage medium having stored therein computer instructions which, when executed on a computer, cause the computer to perform the method of any one of claims 1 to 8.

21. A computer program product, characterized in that the computer program code or instructions, when executed on a computer, cause the computer to perform the method of any of claims 1 to 8.