CN114650096B - Optical path self-adaptive dispersion compensation method, optical module and wavelength division multiplexing system - Google Patents
Optical path self-adaptive dispersion compensation method, optical module and wavelength division multiplexing system Download PDFInfo
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Abstract
The present disclosure relates to an optical path adaptive dispersion compensation method, an optical module, and a wavelength division multiplexing system. The optical path self-adaptive dispersion compensation method comprises the following steps: in a non-coherent wavelength division multiplexing system, an optical fiber Bragg grating is introduced into an optical module to perform optical path dispersion compensation. The disclosure proposes integrating an optical fiber Bragg grating at a receiving end of an optical module to realize dispersion compensation of a transmission optical path system, an optical signal cannot generate attenuation after passing through the grating, and extra power budget is not required to be considered when an optical interface index of the optical module is prepared.
Description
Technical Field
The present disclosure relates to the field of optical communications, and in particular, to an optical path adaptive dispersion compensation method, an optical module, and a wavelength division multiplexing system.
Background
In an optical fiber communication system, the problem of chromatic dispersion is one of the main factors limiting the transmission distance, which causes signal pulses to widen, intersymbol interference to occur, and the error rate to increase. Related art WDM (WAVELENGTH DIVISION MULTIPLEXING, coherent wavelength division multiplexing) technology is not two options of the existing long-distance wavelength division system, and a single wave 100G and above rate system can compensate chromatic dispersion (CD, chromatic dispersion) and PMD (Polarization Mode Dispersion ) through DSP (DIGITAL SIGNAL Process, digital signal processing) inside an optical module, so as to improve the transmission capability of the system.
WDM technology has a tendency to sink like metro edge nodes due to the proliferation of 5G and data center traffic. The high cost of optical modules in coherent WDM systems makes incoherent WDM another option. While incoherent schemes use a direct alignment (IM-DD) optical module, electrical domain dispersion compensation is not possible. Even when operating in the low dispersion O-band, accumulated dispersion can produce relatively high dispersion costs after long distance transmission (e.g., 80 km), limiting the level of further transmission by the system.
Disclosure of Invention
The inventors found through research that: the related art generally uses DCF (Dispersion Compensating Fiber ) to compensate the optical path dispersion, and is also the most common dispersion compensation scheme. But because of the extra loss associated with using a length of fiber, it is necessary to increase the power budget or add optical amplifiers to the system to compensate for the attenuation.
In view of at least one of the above technical problems, the present disclosure provides an optical path adaptive dispersion compensation method, an optical module, and a wavelength division multiplexing system, which implement optical path dispersion compensation using and integrating an FBG (Fiber Bragg Grating ) inside the optical module.
According to one aspect of the present disclosure, there is provided an optical path adaptive dispersion compensation method including:
In a non-coherent wavelength division multiplexing system, an optical fiber Bragg grating is introduced into an optical module to perform optical path dispersion compensation.
In some embodiments of the disclosure, the performing optical path dispersion compensation includes:
and compensating chromatic dispersion generated after the optical signals are transmitted through the transmission optical fiber through grating reflection and reflection time delay of the optical signals with different wavelengths.
In some embodiments of the present disclosure, the introducing a fiber bragg grating into the optical module for optical path dispersion compensation includes:
acquiring chromatic dispersion of an optical signal after being transmitted by a transmission optical fiber;
determining a dispersion compensation value based on the chromatic dispersion;
The adjustment of the dispersion compensation value is achieved by changing the grating period or refractive index.
In some embodiments of the present disclosure, the obtaining the chromatic dispersion of the optical signal after being transmitted through the transmission fiber includes:
acquiring the optical fiber length of a transmission optical fiber through which an optical signal passes;
and determining the accumulated dispersion value of the optical signal transmitted by the section of transmission optical fiber according to the length of the optical fiber, the central wavelength of the optical module, the dispersion coefficient and the dispersion slope.
In some embodiments of the present disclosure, the acquiring the fiber length of the transmission fiber through which the optical signal passes includes:
An optical time domain reflectometer module is arranged in the optical module to measure the length of the optical fiber of the transmission optical fiber.
In some embodiments of the present disclosure, the acquiring the fiber length of the transmission fiber through which the optical signal passes includes:
Receiving an optical signal sent by an opposite-end optical module, and analyzing the modulated top signal through a modulated top signal demodulation device to obtain the sending optical power and the center wavelength of the opposite-end optical module, wherein the opposite-end optical module converts the digital diagnosis monitoring information and the center wavelength of the sending optical power into the modulated top signal and superimposes the modulated top signal in a main service signal;
Determining an optical signal attenuation value according to the digital diagnosis monitoring information of the transmitting optical power and the central wavelength of the opposite-end optical module and the receiving optical power of the local-end optical module;
And determining the optical fiber length of the transmission optical fiber through which the optical signal passes according to the attenuation coefficient and the optical signal attenuation value.
In some embodiments of the disclosure, the adjusting of the dispersion compensation value by changing the grating period or the refractive index comprises:
The adjustment of the dispersion compensation value is achieved by changing the grating stress or temperature parameter.
In some embodiments of the present disclosure, the introducing the fiber bragg grating into the optical module for optical path dispersion compensation further includes:
Under the condition that the optical module is changed in application scene, the accumulated chromatic dispersion is recalculated, and the grating stress or temperature parameter is adjusted in real time, so that the adjustment of the chromatic dispersion compensation value is realized.
According to another aspect of the present disclosure, there is provided an optical module including:
The optical fiber Bragg grating FBG dispersion compensation unit is arranged in the optical module and is used for carrying out optical path dispersion compensation in an incoherent wavelength division multiplexing system.
In some embodiments of the present disclosure, the FBG dispersion compensation unit is configured to compensate chromatic dispersion generated after an optical signal is transmitted through a transmission optical fiber by grating reflection and reflection delay of the optical signal with different wavelengths.
In some embodiments of the present disclosure, the optical module further comprises:
the chromatic dispersion measuring and calculating unit is used for obtaining chromatic dispersion of the optical signals after being transmitted by the transmission optical fiber;
An FBG dispersion compensation unit for determining a dispersion compensation value according to the chromatic dispersion; the adjustment of the dispersion compensation value is achieved by changing the grating period or refractive index.
In some embodiments of the present disclosure, a chromatic dispersion measurement unit is configured to obtain an optical fiber length of a transmission optical fiber through which an optical signal passes; and determining the accumulated dispersion value of the optical signal transmitted by the section of transmission optical fiber according to the length of the optical fiber, the central wavelength of the optical module, the dispersion coefficient and the dispersion slope.
In some embodiments of the present disclosure, the chromatic dispersion measurement unit is configured to measure the fiber length of the transmission fiber by using an optical time domain reflectometer module built in the optical module.
In some embodiments of the present disclosure, the optical module further comprises:
The device comprises a top-adjusting signal analyzing unit, a top-adjusting signal demodulating unit and a top-adjusting signal analyzing unit, wherein the top-adjusting signal analyzing unit is used for receiving an optical signal sent by an opposite-end optical module, and analyzing the top-adjusting signal through the top-adjusting signal demodulating unit to obtain the sending optical power and the center wavelength of the opposite-end optical module, wherein the opposite-end optical module converts digital diagnosis monitoring information and the center wavelength of the sending optical power into the top-adjusting signal and superimposes the top-adjusting signal in a main service signal;
The chromatic dispersion measuring and calculating unit is used for determining an optical signal attenuation value according to the digital diagnosis monitoring information of the transmitting optical power and the central wavelength of the opposite-end optical module and the receiving optical power of the local-end optical module; and determining the optical fiber length of the transmission optical fiber through which the optical signal passes according to the attenuation coefficient and the optical signal attenuation value.
In some embodiments of the present disclosure, the FBG dispersion compensation unit is configured to implement the adjustment of the dispersion compensation value by changing the grating stress or temperature parameter.
In some embodiments of the present disclosure, a chromatic dispersion measurement unit for recalculating accumulated dispersion in case of an optical module application scene change;
the FBG dispersion compensation unit is used for adjusting the dispersion compensation value in real time according to the recalculated accumulated dispersion; and adjusting grating stress or temperature parameters in real time to realize adjustment of the dispersion compensation value.
According to another aspect of the present disclosure, there is provided a wavelength division multiplexing system including an optical module as described in any one of the above embodiments.
The present disclosure proposes for the first time that an FBG is integrated at the receiving end of an optical module to implement dispersion compensation for a transmission optical path system, an optical signal will not attenuate after passing through a grating, and no extra power budget is required to be considered when an optical interface index of the optical module is made.
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In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.
Fig. 1 is a schematic diagram of some embodiments of the optical path adaptive dispersion compensation method of the present disclosure.
Fig. 2 is a schematic diagram of a chirped grating dispersion compensation principle in some embodiments of the present disclosure.
Fig. 3 is a schematic diagram of another embodiment of the optical path adaptive dispersion compensation method of the present disclosure.
Fig. 4 is a schematic diagram of some embodiments of the disclosed optical module.
Fig. 5 is a schematic diagram of some embodiments of a wavelength division multiplexing system of the present disclosure.
Fig. 6 is a schematic diagram of other embodiments of the optical module of the present disclosure.
Fig. 7 is a schematic diagram of chromatic dispersion obtained by an OTDR method in some embodiments of the disclosure.
Fig. 8 is a schematic diagram of chromatic dispersion obtained by an optical module topping method according to some embodiments of the present disclosure.
Fig. 9 is a schematic diagram of yet other embodiments of the optical module of the present disclosure.
Detailed Description
The following description of the technical solutions in the embodiments of the present disclosure will be made clearly and completely with reference to the accompanying drawings in the embodiments of the present disclosure, and it is apparent that the described embodiments are only some embodiments of the present disclosure, not all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. Based on the embodiments in this disclosure, all other embodiments that a person of ordinary skill in the art would obtain without making any inventive effort are within the scope of protection of this disclosure.
The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless it is specifically stated otherwise.
Meanwhile, it should be understood that the sizes of the respective parts shown in the drawings are not drawn in actual scale for convenience of description.
Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate.
In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
Fig. 1 is a schematic diagram of some embodiments of the optical path adaptive dispersion compensation method of the present disclosure. Preferably, the present embodiment may be performed by the optical module of the present disclosure. As shown in fig. 1, the optical path adaptive dispersion compensation method may include step 10, in which:
and step 10, introducing an optical fiber Bragg grating into the optical module to perform optical path dispersion compensation in the incoherent wavelength division multiplexing system.
In some embodiments of the present disclosure, the fiber bragg grating may be CFBG (Chirped Fiber Bragg Grating, chirped optical bragg grating).
In some embodiments of the present disclosure, the fiber bragg grating may be a chirped grating with a non-uniform periodic distribution.
In some embodiments of the present disclosure, the step of performing optical path dispersion compensation may include: and compensating chromatic dispersion generated after the optical signals are transmitted through the transmission optical fiber through grating reflection and reflection time delay of the optical signals with different wavelengths.
In some embodiments of the present disclosure, the transmission fiber may be a common single mode fiber.
In some embodiments of the present disclosure, in WDM systems, optical modules of different wavelengths need to take into account grating bandwidth and period when selecting gratings, ensuring that bragg conditions are met to produce strong reflections at a particular wavelength.
According to the embodiment of the disclosure, the dispersion problem caused by the transmission of the signal light through the common single mode fiber is compensated through grating reflection and reflection time delay of the optical signals with different wavelengths, and the original signal is recovered.
The dispersion compensation scheme realized based on the optical module in the embodiment of the disclosure is to compensate each channel of the WDM system respectively, and the dispersion condition of other channels in the system is not required to be considered, so that the method is more suitable for the characteristic of flexible networking of the current optical transmission network.
The fiber bragg grating disclosed by the embodiment of the disclosure is small in size, low in insertion loss, good in compatibility with optical fibers, small in nonlinear influence and easy to integrate with an optical module.
Fig. 2 is a schematic diagram of a chirped grating dispersion compensation principle in some embodiments of the present disclosure. As shown in fig. 2, for an optical signal of an arbitrary wavelength, the short wavelength (blue-shift) component is transmitted at a high speed, and the long wavelength (red-shift) component is transmitted at a low speed, so that the optical signal is widened after being transmitted through the optical fiber. Therefore, a grating whose period of use varies in the axial direction is selected, and when the Bragg condition is satisfied, optical signals of different wavelength components enter the grating to be reflected at different positions. If the end with the larger grating period is placed in front, the red shift component reaches the Bragg condition first and is reflected; the end with small grating period is placed at the back, so that blue shift component is reflected at the back end of the grating, and the widened signal can be restored.
Fig. 3 is a schematic diagram of another embodiment of the optical path adaptive dispersion compensation method of the present disclosure. Preferably, the present embodiment may be performed by the optical module of the present disclosure. As shown in fig. 3, the optical path adaptive dispersion compensation method may include at least one of steps 11 to 14, wherein:
And step 11, in the incoherent wavelength division multiplexing system, acquiring chromatic dispersion of the optical signal after being transmitted by the transmission optical fiber.
In some embodiments of the present disclosure, step 11 may comprise at least one of steps 111-112, wherein:
step 111, obtaining the optical fiber length of the transmission optical fiber through which the optical signal passes.
In some embodiments of the present disclosure, step 111 may include: an optical time domain reflectometer module is arranged in the optical module to measure the length of the optical fiber of the transmission optical fiber.
In other embodiments of the present disclosure, step 111 may comprise at least one of step 1111-step 1113, wherein:
And 1111, receiving the optical signal sent by the opposite-end optical module, and analyzing the modulated top signal by a modulated top signal demodulation device to obtain the sending optical power and the center wavelength of the opposite-end optical module, wherein the opposite-end optical module converts the digital diagnosis monitoring information and the center wavelength of the sending optical power into the modulated top signal, and the modulated top signal is superposed in the main service signal.
Step 1112, determining an optical signal attenuation value according to the digital diagnostic monitoring information of the transmitting optical power and the center wavelength of the opposite optical module and the receiving optical power of the local optical module.
Step 1113, determining the optical fiber length of the transmission optical fiber through which the optical signal passes according to the attenuation coefficient and the optical signal attenuation value.
And step 112, determining the accumulated dispersion value of the optical signal transmitted by the section of transmission optical fiber according to the length of the optical fiber, the central wavelength of the optical module, the dispersion coefficient and the dispersion slope.
And step 12, determining a dispersion compensation value according to the chromatic dispersion.
In some embodiments of the present disclosure, the FBG dispersion compensation value D FBG can be preconfigured according to equation (1):
Ds(λ)*L＝-α*DFBG(λ) (1)
In the formula (1), D s (λ) is the dispersion coefficient of the wavelength λ in the common single mode fiber, L is the fiber length, and the grating length is negligible with respect to the fiber length. Considering zero dispersion tends to make the optical signal satisfy the phase matching condition, thereby generating a nonlinear effect. If transmission performance is degraded due to non-linearity problems, the dispersion compensation value DFBG can be adjusted to make overcompensation or undercompensation, and then the conversion factor alpha is not equal to 1.
In some embodiments of the present disclosure, the setting of the dispersion compensation value requires consideration in combination with a plurality of parameters such as the transmission distance, the operating wavelength, etc. of the optical module, so as to evaluate the accumulated dispersion value generated after the transmission through the common single mode fiber. The above embodiments of the present disclosure provide a method for dynamically adjusting the dispersion compensation value, in which the reflection wavelength is adjusted by stressing the grating or changing the temperature, and a relationship between the dispersion compensation and the chromatic dispersion actually generated is established, because the reflection wavelength is related to the grating period and the effective refractive index of the grating region.
In some embodiments of the present disclosure, the chromatic dispersion of a common single-mode fiber is calculated by means of real-time measurement or out-of-band modulation (e.g., roof-shifting) of an optical module.
And step 13, adjusting the dispersion compensation value by changing the grating period or the refractive index.
In some embodiments of the present disclosure, step 13 may include: the adjustment of the dispersion compensation value is achieved by changing the grating stress or temperature parameter.
And step 14, under the condition that the optical module applies scene change, calculating accumulated chromatic dispersion again, and adjusting grating stress or temperature parameters in real time to realize adjustment of the chromatic dispersion compensation value.
The above embodiments of the present disclosure propose to integrate FBGs at the receiving end of an optical module to realize dispersion compensation for a transmission optical system for the first time. The FBG of the embodiment of the disclosure is small in size, low in insertion loss, good in compatibility with optical fibers, small in nonlinear influence, easy to integrate with an optical module and high in cost performance.
Unlike DCF schemes, the optical signals of the above embodiments of the present disclosure hardly attenuate after passing through the grating, and no extra power budget is required to be considered when the optical interface index of the optical module is prepared. The dispersion compensation scheme realized based on the optical module in the above embodiment of the present disclosure is to compensate each wavelength separately, so that the configuration of the whole wavelength division system can be prevented from being changed, and the influence on other channels in the wavelength division system is reduced.
Fig. 4 is a schematic diagram of some embodiments of the disclosed optical module. As shown in fig. 4, the optical module of the present disclosure may include an FBG dispersion compensating unit 41 disposed inside the optical module, wherein:
the FBG dispersion compensation unit 41 is used for performing optical path dispersion compensation in the incoherent wavelength division multiplexing system.
In some embodiments of the present disclosure, the FBG dispersion compensation unit is configured to compensate chromatic dispersion generated after an optical signal is transmitted through a transmission optical fiber by grating reflection and reflection delay of the optical signal with different wavelengths.
In some embodiments of the present disclosure, as shown in fig. 4, a service signal light with a certain wavelength is transmitted through an optical fiber with a certain length to generate chromatic dispersion, and then enters an FBG chromatic dispersion compensation unit inside an optical module, wavelength components meeting bragg conditions are strongly reflected in sequence, and the remaining small amount of light is not processed as transmitted light. The FBG dispersion compensation unit is a periodically-changing fiber grating, so that the widened service signal is adjusted and recovered. The recovered service signals are sequentially transmitted through core photoelectric devices such as a light signal receiving and detecting unit (PIN/APD), a TIA (Trans-IMPEDANCE AMPLIFIER, a transimpedance amplifier), a LA (LINEAR AMPLIFIER, a linear amplifier) and the like, and finally converted into complete electric signals to be output, wherein the PIN is a photodiode, and the APD is AVALANCHE PHOTON DIODE (avalanche photodiode).
Fig. 5 is a schematic diagram of some embodiments of a wavelength division multiplexing system of the present disclosure. As shown in fig. 5, the wavelength division multiplexing system of the present disclosure may include a first optical module 51 and a second optical module 52, where the first optical module 51 and the second optical module 52 are connected by an optical fiber, and the first optical module 51 and the second optical module 52 are opposite optical modules.
In some embodiments of the present disclosure, the wavelength division multiplexing system of the present disclosure may be a non-coherent wavelength division multiplexing system.
The wavelength division multiplexing system can realize optical path self-adaptive dispersion compensation based on the optical module.
In some embodiments of the present disclosure, the first optical module 51 and the second optical module 52 may be single channel IM-DD optical modules.
In some embodiments of the present disclosure, the first optical module 51 and the second optical module 52 each include a transmitting side structure and a receiving side structure.
In some embodiments of the present disclosure, the first and second light modules 51 and 52 may be implemented as the light modules described in any of the embodiments described above (e.g., the embodiment of fig. 4).
In some embodiments of the present disclosure, a single channel optical module (e.g., the first optical module 51) using IM-DD technology has only one laser on the transmit side, and is modulated to produce an output optical signal with a unique center wavelength. The output optical signal is transmitted in the optical fiber, and the propagation speed of different frequency components is different, so that the optical signal pulse is widened, and chromatic dispersion is formed, thereby influencing the transmission performance.
In some embodiments of the present disclosure, the laser of the first optical module 51 is modulated to produce an output optical signal having a unique center wavelength. The output optical signal is transmitted in an 80km optical fiber, and the optical signal pulse is widened due to the different propagation speeds of different frequency components, so that chromatic dispersion is generated. The second optical module 52 integrates a chromatic dispersion measuring and calculating unit at the receiving end, and performs dispersion calculation on the optical signal transmitted by the common single-mode optical fiber. The length of the optical fiber is obtained, and the accumulated dispersion value of the optical signal at the wavelength is calculated by combining the dispersion coefficient and the dispersion slope.
Fig. 6 is a schematic diagram of other embodiments of the optical module of the present disclosure. The optical module as shown in fig. 5 (e.g., the second optical module 52 of the embodiment of fig. 5) may include a chromatic dispersion measurement unit 42 and an FBG dispersion compensation unit 41, wherein:
In some embodiments of the present disclosure, the optical module as shown in fig. 6 may be a single channel optical module using IM-DD technology.
The chromatic dispersion measuring unit 42 is configured to obtain chromatic dispersion of the optical signal after being transmitted through the transmission fiber.
In some embodiments of the present disclosure, the chromatic dispersion measurement unit 42 may be configured to obtain a fiber length of a transmission fiber through which the optical signal passes; and determining the accumulated dispersion value of the optical signal transmitted by the section of transmission optical fiber according to the length of the optical fiber, the central wavelength of the optical module, the dispersion coefficient and the dispersion slope.
In some embodiments of the present disclosure, the chromatic dispersion measurement unit 42 may be configured to perform dispersion calculation on an optical signal transmitted through a common single-mode fiber, that is, obtain the length of the optical fiber, and calculate the cumulative dispersion value of the optical signal at the wavelength by combining the dispersion coefficient and the dispersion slope.
An FBG dispersion compensating unit 41 for determining a dispersion compensation value according to the chromatic dispersion; the adjustment of the dispersion compensation value is achieved by changing the grating period or refractive index.
In some embodiments of the present disclosure, the FBG dispersion compensating unit 41 may be used to compensate for dispersion generated in the system by a chirped FBG integrated inside an optical module (e.g., the second optical module 52 of the embodiment of fig. 5); selecting a proper dispersion compensation value according to the calculated accumulated dispersion; and then the desired dispersion compensation value is called out by changing the grating stress or temperature parameter.
In some embodiments of the present disclosure, when the optical module changes the application scene, such as the transmission distance changes, the chromatic dispersion measuring unit 42 at the receiving end of the optical module recalculates the accumulated dispersion, and the FBG dispersion compensating unit 41 adjusts the relevant parameters in real time to meet the system dispersion compensation requirement.
In some embodiments of the present disclosure, the chromatic dispersion measurement unit 42 may be configured to calculate the chromatic dispersion of the ordinary single-mode fiber by real-time measurement or by out-of-band modulation (e.g., roof-of-band modulation) of the optical module.
The following describes the way of using two ways to obtain the chromatic dispersion of the common single-mode fiber for the chromatic dispersion measuring unit through a specific embodiment.
Mode one, real-time measurement
In some embodiments of the present disclosure, the chromatic dispersion measurement unit 42 may be used to measure the fiber length of the transmission fiber by an OTDR (Optical Time-Domain Reflectometer, optical Time domain reflectometer) module built in the Optical module.
Fig. 7 is a schematic diagram of chromatic dispersion obtained by an OTDR method in some embodiments of the disclosure. Fig. 7 also shows a schematic structural diagram of the transmitting side of the optical module of the present disclosure.
As shown in fig. 7, the optical module incorporates an OTDR module to measure the length of an optical fiber, and calculate the dispersion after transmission through the optical fiber. As shown in fig. 7, the OTDR function module is integrated on the transmitting side of the optical module and coupled with the main service optical signal through the combiner-splitter. The method can detect the length of the optical fiber transmitted by the optical module, calculate and obtain the accumulated dispersion transmitted by the optical fiber according to the central wavelength of the optical module, and report the result through an IIC (Inter-INTEGRATED CIRCUIT integrated circuit bus) interface.
Mode two, optical module out-of-band roof-adjusting mode calculation
Fig. 8 is a schematic diagram of chromatic dispersion obtained by an optical module topping method according to some embodiments of the present disclosure. Fig. 8 also provides a schematic diagram of other embodiments of the wavelength division multiplexing system of the present disclosure. The embodiment of fig. 8 uses optical module roofing techniques for dispersion estimation. The embodiment of fig. 8 performs some OAM (Operation Administration Maintenance ) information transfer of the optical module by superimposing a low frequency small amplitude signal on the high speed traffic signal. As shown in fig. 8, the transmission optical power DDM (Digital Diagnostic Monitoring, digital diagnostic monitor) information and the center wavelength of the optical module 2 are converted into a modulated top signal, which is superimposed in the main service signal. The optical module 1 receives the optical information or analyzes the modulated top signal by a modulated top signal demodulation device, thereby obtaining the transmission optical power and the center wavelength of the optical module 2. The optical module MCU (Microcontroller Unit, micro control unit) obtains the optical signal attenuation based on these information and the received optical power DDM of the optical module 1. Under the condition of known attenuation coefficient, the length of the optical fiber can be calculated, and the accumulated dispersion transmitted through the section of optical fiber can be calculated according to the method of the first mode. Compared with the first mode, the second mode does not need to introduce an extra light source and a detection device, and has low cost.
Fig. 9 is a schematic diagram of yet other embodiments of the optical module of the present disclosure. The optical module as shown in fig. 9 (e.g., the second optical module 52 of the embodiment of fig. 5 or the optical module 1 of the embodiment of fig. 8) may include a tunable top signal analyzing unit 43, a chromatic dispersion measuring unit 42, and an FBG dispersion compensating unit 41, in which:
The top-adjusting signal analyzing unit 43 is configured to receive an optical signal sent by the opposite-end optical module, perform top-adjusting signal analysis through a top-adjusting signal demodulating device, and obtain a sending optical power and a center wavelength of the opposite-end optical module, where the opposite-end optical module converts digital diagnostic monitoring information and the center wavelength of the sending optical power into a top-adjusting signal, and superimposes the top-adjusting signal in the main service signal;
A chromatic dispersion measuring and calculating unit 42, configured to determine an optical signal attenuation value according to digital diagnostic monitoring information of the transmission optical power and the center wavelength of the opposite optical module, and the reception optical power of the local optical module; determining the optical fiber length of a transmission optical fiber through which the optical signal passes according to the attenuation coefficient and the optical signal attenuation value; and determining the accumulated dispersion value of the optical signal transmitted by the section of transmission optical fiber according to the length of the optical fiber, the central wavelength of the optical module, the dispersion coefficient and the dispersion slope.
An FBG dispersion compensating unit 41 for determining a dispersion compensation value according to the chromatic dispersion; the adjustment of the dispersion compensation value is achieved by changing the grating period or refractive index.
The above embodiments of the present disclosure introduce chirped fiber bragg gratings in an optical module to implement dispersion compensation in a non-coherent WDM system.
The above embodiments of the present disclosure establish a relationship between a dispersion compensation value and an actual chromatic dispersion, and employ a mechanism for adaptively adjusting the dispersion compensation value. The chromatic dispersion of the transmission fiber is calculated or measured to find the dispersion compensation value to be adjusted, and then the adjustment of the dispersion compensation value is realized by changing the grating period or refractive index.
The above embodiments of the present disclosure use and integrate a Fiber Bragg Grating (FBG) inside an optical module to achieve optical path dispersion compensation. According to the embodiment of the disclosure, the dispersion problem caused by the transmission of the signal light through the common single mode fiber is compensated through grating reflection and reflection time delay of the optical signals with different wavelengths, and the original signal is recovered. According to the optical module disclosed by the embodiment of the disclosure, the accumulated chromatic dispersion is calculated, so that the chromatic dispersion compensation value can be adjusted in real time to meet the requirements of scenes with different transmission distances.
The above embodiments of the present disclosure achieve low cost adaptive dispersion compensation through optical modules without replacing existing network equipment.
The above embodiments of the disclosure propose that the grating dispersion compensation method is realized based on the existing optical device (such as grating and OTDR) and the technical scheme (such as top modulation), and the industrial chain support is good. The chirped grating has small volume, low insertion loss, good compatibility with optical fibers, small nonlinear influence, easy integration with an optical module and high cost performance. The embodiment of the disclosure is introduced into the optical module in an integrated manner, and can utilize the existing network equipment only by increasing the cost of a certain optical module.
The modulated top signal parsing unit 43 and the chromatic dispersion measurement unit 42 described above may be implemented as general purpose processors, programmable Logic Controllers (PLCs), digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any suitable combination thereof, for performing the functions described herein.
Thus far, the present disclosure has been described in detail. In order to avoid obscuring the concepts of the present disclosure, some details known in the art are not described. How to implement the solutions disclosed herein will be fully apparent to those skilled in the art from the above description.
Those of ordinary skill in the art will appreciate that all or a portion of the steps implementing the above embodiments may be implemented by hardware, or may be implemented by a program indicating that the relevant hardware is implemented, where the program may be stored on a non-transitory computer readable storage medium, where the storage medium may be a read-only memory, a magnetic disk or optical disk, etc.
The description of the present disclosure has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.
Claims (11)
1. An optical path adaptive dispersion compensation method, comprising:
In a non-coherent wavelength division multiplexing system, introducing an optical fiber Bragg grating into an optical module to perform optical path dispersion compensation;
The optical path dispersion compensation by introducing the fiber Bragg grating into the optical module comprises the following steps:
acquiring chromatic dispersion of an optical signal after being transmitted by a transmission optical fiber;
determining a dispersion compensation value based on the chromatic dispersion;
The adjustment of the dispersion compensation value is realized by changing the grating period or refractive index;
Wherein, the chromatic dispersion of the obtained optical signal after being transmitted by the transmission optical fiber comprises:
acquiring the optical fiber length of a transmission optical fiber through which an optical signal passes;
Determining the accumulated dispersion value of the optical signal transmitted by the transmission optical fiber according to the length of the optical fiber, the central wavelength of the optical module, the dispersion coefficient and the dispersion slope;
wherein, the optical fiber length of the transmission optical fiber through which the acquired optical signal passes includes:
Receiving an optical signal sent by an opposite-end optical module, and analyzing the modulated top signal through a modulated top signal demodulation device to obtain the sending optical power and the center wavelength of the opposite-end optical module, wherein the opposite-end optical module converts the digital diagnosis monitoring information and the center wavelength of the sending optical power into the modulated top signal and superimposes the modulated top signal in a main service signal;
Determining an optical signal attenuation value according to the digital diagnosis monitoring information of the transmitting optical power and the central wavelength of the opposite-end optical module and the receiving optical power of the local-end optical module;
And determining the optical fiber length of the transmission optical fiber through which the optical signal passes according to the attenuation coefficient and the optical signal attenuation value.
2. The optical path adaptive dispersion compensation method according to claim 1, wherein the performing optical path dispersion compensation includes:
and compensating chromatic dispersion generated after the optical signals are transmitted through the transmission optical fiber through grating reflection and reflection time delay of the optical signals with different wavelengths.
3. The optical path adaptive dispersion compensation method according to claim 1 or 2, wherein the optical fiber length of the transmission optical fiber through which the acquired optical signal passes includes:
An optical time domain reflectometer module is arranged in the optical module to measure the length of the optical fiber of the transmission optical fiber.
4. The optical path adaptive dispersion compensation method according to claim 1 or 2, wherein said adjusting the dispersion compensation value by changing the grating period or refractive index comprises:
The adjustment of the dispersion compensation value is achieved by changing the grating stress or temperature parameter.
5. The method for optical path adaptive dispersion compensation according to claim 1 or 2, wherein the introducing the fiber bragg grating into the optical module for optical path dispersion compensation further comprises:
Under the condition that the optical module is changed in application scene, the accumulated chromatic dispersion is recalculated, and the grating stress or temperature parameter is adjusted in real time, so that the adjustment of the chromatic dispersion compensation value is realized.
6. An optical module, comprising:
the optical fiber Bragg grating FBG dispersion compensation unit is arranged in the optical module and is used for carrying out optical path dispersion compensation in an incoherent wavelength division multiplexing system;
the chromatic dispersion measuring and calculating unit is used for obtaining chromatic dispersion of the optical signals after being transmitted by the transmission optical fiber;
the FBG dispersion compensation unit is used for determining a dispersion compensation value according to the chromatic dispersion; the adjustment of the dispersion compensation value is realized by changing the grating period or refractive index;
The chromatic dispersion measuring and calculating unit is used for obtaining the optical fiber length of the transmission optical fiber through which the optical signal passes; determining the accumulated dispersion value of the optical signal transmitted by the transmission optical fiber according to the length of the optical fiber, the central wavelength of the optical module, the dispersion coefficient and the dispersion slope;
wherein, the optical module further includes:
The device comprises a top-adjusting signal analyzing unit, a top-adjusting signal demodulating unit and a top-adjusting signal analyzing unit, wherein the top-adjusting signal analyzing unit is used for receiving an optical signal sent by an opposite-end optical module, and analyzing the top-adjusting signal through the top-adjusting signal demodulating unit to obtain the sending optical power and the center wavelength of the opposite-end optical module, wherein the opposite-end optical module converts digital diagnosis monitoring information and the center wavelength of the sending optical power into the top-adjusting signal and superimposes the top-adjusting signal in a main service signal;
The chromatic dispersion measuring and calculating unit is used for determining an optical signal attenuation value according to the digital diagnosis monitoring information of the transmitting optical power and the central wavelength of the opposite-end optical module and the receiving optical power of the local-end optical module; and determining the optical fiber length of the transmission optical fiber through which the optical signal passes according to the attenuation coefficient and the optical signal attenuation value.
7. The optical module of claim 6, wherein the optical module is configured to,
And the FBG dispersion compensation unit is used for compensating chromatic dispersion generated after the optical signals are transmitted through the transmission optical fiber through grating reflection and reflection time delay of the optical signals with different wavelengths.
8. The light module of claim 6 or 7, wherein the light module comprises a plurality of light modules,
The chromatic dispersion measuring and calculating unit is used for measuring the optical fiber length of the transmission optical fiber through an optical time domain reflectometer module arranged in the optical module.
9. The light module of claim 6 or 7, wherein the light module comprises a plurality of light modules,
And the FBG dispersion compensation unit is used for realizing the adjustment of the dispersion compensation value through the change of the grating stress or the temperature parameter.
10. The light module of claim 6 or 7, wherein the light module comprises a plurality of light modules,
The chromatic dispersion measuring and calculating unit is used for calculating accumulated dispersion again under the condition that the optical module is subjected to scene change;
the FBG dispersion compensation unit is used for adjusting the dispersion compensation value in real time according to the recalculated accumulated dispersion; and adjusting grating stress or temperature parameters in real time to realize adjustment of the dispersion compensation value.
11. A wavelength division multiplexing system comprising an optical module according to any of claims 6-10.
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| CN103281129A (en) * | 2013-05-20 | 2013-09-04 | 青岛海信宽带多媒体技术有限公司 | Optical module and electric domain dispersion compensation method thereof |
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