CN111751932A - Wavelength locking method and device - Google Patents

Wavelength locking method and device Download PDF

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Publication number
CN111751932A
CN111751932A CN201910252286.5A CN201910252286A CN111751932A CN 111751932 A CN111751932 A CN 111751932A CN 201910252286 A CN201910252286 A CN 201910252286A CN 111751932 A CN111751932 A CN 111751932A
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Prior art keywords
intermediate variable
power value
coordinate transformation
transformation matrix
wavelength
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CN201910252286.5A
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CN111751932B (en
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张诗劼
冀瑞强
米光灿
张欣
周素杰
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Priority to CN201910252286.5A priority Critical patent/CN111751932B/en
Priority to PCT/CN2020/072666 priority patent/WO2020199726A1/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29331—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by evanescent wave coupling
    • G02B6/29335—Evanescent coupling to a resonator cavity, i.e. between a waveguide mode and a resonant mode of the cavity
    • G02B6/29338—Loop resonators
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29346—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by wave or beam interference
    • G02B6/29361—Interference filters, e.g. multilayer coatings, thin film filters, dichroic splitters or mirrors based on multilayers, WDM filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29346—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by wave or beam interference
    • G02B6/29361—Interference filters, e.g. multilayer coatings, thin film filters, dichroic splitters or mirrors based on multilayers, WDM filters
    • G02B6/29362—Serial cascade of filters or filtering operations, e.g. for a large number of channels

Abstract

The embodiment of the application discloses a wavelength locking method and a wavelength locking device, which are used for improving the accuracy of wavelength locking of a high-order micro-ring. The method specifically comprises the following steps: the wavelength locking device acquires an incident light signal; the wavelength locking device loads an initial voltage value combination for the cascade filter according to a lookup table and the wavelength of target filtering, wherein the lookup table is used for indicating the mapping relation between the filtering wavelength and the voltage value of the cascade filter, and the cascade filter comprises at least two rings; the wavelength locking device generates an intermediate variable combination according to a first coordinate transformation matrix and the initial voltage value combination, wherein the first coordinate transformation matrix is an Nx-Nth order matrix; the wavelength locking device selects a target intermediate variable from the intermediate variable combination to carry out iterative feedback by a first preset step length and the first coordinate transformation matrix, and records the power value of the cascade filter; the wavelength locker filters the target filter from the incoming optical signal when the power value is at a maximum.

Description

Wavelength locking method and device
Technical Field
The present application relates to the field of communications, and in particular, to a method and an apparatus for wavelength locking.
Background
In a conventional optical communication system, precision of uploading and downloading of optical wavelengths is required to be high in a metropolitan area network node. The optical filter is essential to select the optical wavelength, and when a series of optical signals come in at the receiving end, the optical filter needs to selectively download and upload the specified optical signals to the optical wavelength. An optical filter may be composed of cascaded micro-rings, or may be composed of cascaded structures such as MZI. By design, the physical size and the characteristics of the cascade devices are differentiated, so that the vernier effect of the FSR can be used for expanding the tuning range of the filter, namely the filtering wavelength range. The filter based on the cascade micro-ring has the advantages of low power consumption, small volume, easy mass integration and the like, can meet the requirements of optical communication on high bandwidth, low power consumption and high integration level, and is a component with great prospect. The cascade micro-ring filter is formed by connecting N micro-rings In series and is provided with four ports, namely In, Thru, Add and Drop. The filtering spectral lines of all the micro-rings are different, and the filtering spectral lines of all the micro-rings can be moved left and right by heating the micro-rings through a metal layer heater (heater) designed on the micro-rings. When the filter spectrum lines of all the cascade micro-rings have the maximum projection rate under a certain wavelength lambda, the optical signals with the wavelength lambda In a series of optical signals entering from the In port can be filtered out through the Drop port. Since the interval of the incident light wavelength is small for the optical filter, the wavelength point of the lower wave must be accurate to the range of 1nm, and the corresponding wavelength of the lower wave should be kept constant in response to the external environment change in order to make the performance thereof superior. The cascade micro-loop filter can stabilize the resonance peak of the cascade micro-loop filter in a dynamic balance state through continuous feedback control by a feedback system such as that shown in fig. 1.
However, the present invention only provides a feedback control method for a dual-loop cascade micro-loop filter. As shown in fig. 2, for the two-loop cascade filter, the phases corresponding to the two loops are represented by the intermediate variable, two-loop phase sum and two-loop phase difference, where the two-loop phase sum is Φavg＝(φ1+φ2) A phase difference between the two rings of phidiff＝(φ1-φ2) /2, wherein phi1Phase Shift around the first micro-Ring (RTPS), phi2Is the second oneRing corresponds to RTPS. Phi is aavgAnd phidiffIs zero for phi in each iterationavgOr phidiffThe value of (1) is increased by a variable of a small step length so as to change the voltage on two rings at a time, then the reading value of an off-chip Photodetector (PD) is detected, whether the PD value is increased or decreased compared with the last time is compared, and then the judgment and feedback are carried out to continue to increase or decrease phiavgOr phidiffThe value of (2) achieves the purpose of changing the phase positions on the two micro-rings, thereby achieving the effect of voltage linkage of the two rings.
However, as communication systems are developed, the Free Spectral Range (FSR) of the filter is also increased, and therefore, the filter mostly adopts a high-order micro-ring filter with vernier effect or a cascaded MZI filter. The high-order micro-ring filter or the cascaded MZI filter with the vernier effect has higher sensitivity to wavelength, and errors caused by inaccurate wavelength of each ring resonance peak are increased exponentially due to the interference of severe change of external environment temperature, jump of wavelength, jitter, drift and the like. Therefore, the method of converting the voltage on the ring and the phase difference between the ring and the two rings is not suitable for the locking control of the high-order micro-ring.
Disclosure of Invention
The embodiment of the application provides a wavelength locking method and a wavelength locking device, which are used for improving the accuracy of wavelength locking of a high-order micro-ring.
In a first aspect, an embodiment of the present application provides a wavelength locking method, which is applied to a cascaded filter including N rings, where N is an integer greater than or equal to 2, and the wavelength locking method specifically includes: the wavelength locking device establishes a lookup table for indicating the corresponding relation of the filtering wavelength of the cascade filter and the voltage value combination of the cascade filter; then, under the condition that the wavelength locking device acquires an incident light signal and determines the wavelength of the target filtering of the cascade filter, the wavelength locking device loads an initial voltage value combination for the cascade filter; the wavelength locking device determines an intermediate variable combination according to a coordinate transformation matrix and the initial voltage value combination, wherein the coordinate transformation matrix is an N x N matrix; the wavelength locking device adjusts at least one intermediate variable in the intermediate variable combination according to a first preset step length to carry out iterative feedback adjustment, and records the adjusted power value of the cascade filter; the wavelength locker outputs the target filter from the incident optical signal when the power value of the cascade filter is maximum.
In this embodiment, the cascade filter may be composed of N micro-rings, may also be composed of N Mach-Zehnder interferometers (MZIs) or other possible filter devices, and is not limited herein.
In the embodiment, the wavelength locking device generates the intermediate variable by using the coordinate transformation matrix and performs iterative feedback in a linkage manner, so that the wavelength locking precision is higher, the response to the influence of the external environment is quicker, and the judgment on the good locking state becomes more accurate and better.
Optionally, the wavelength locker may generate the intermediate variable combination as follows:
the wavelength locking device selects the first coordinate transformation matrix according to a preset condition based on a matrix condition number, wherein the matrix condition number is within a preset range, and the first coordinate transformation matrix is an N x N matrix; and finally, the wavelength locking device generates the intermediate variable combination by using a matrix equation according to the first coordinate transformation matrix and the initial voltage value combination. Wherein the matrix equation is PPi＝A*φi(ii) a I is equal to N, PPiFor the intermediate variable, the A is the first coordinate transformation matrix, the phiiIs a jitter voltage value between the initial voltage value and a target voltage value, the target voltage value is a voltage value loaded when the cascade filter is stable, phiiIs greater than a noise value of circuitry of the cascaded filter. For example, if the cascaded filter includes 4 micro-loops, the matrix equation is PPi＝A*φi(i ═ 1,2,3, 4). That is, the intermediate variables after coordinate transformation matrix can be as follows:
PP1＝A*φ1+A*φ2+A*φ3+A*φ4；
PP2＝A*φ1+A*φ2+A*φ3+A*φ4；
PP3＝A*φ1+A*φ2+A*φ3+A*φ4；
PP4＝A*φ1+A*φ2+A*φ3+A*φ4；
in practical cases, each micro-ring is subjected to a corresponding voltage value, and each micro-ring corresponds to a corresponding phase shift around the ring. Due to the process tolerance, the micro-ring has a certain deviation between the winding phase shift loaded according to the lookup table and the ideal phase shift, so the voltage value on the micro-ring needs to be adjusted correspondingly, that is, the winding phase shift of the micro-ring is adjusted correspondingly1,φ2,φ3,φ4And the jitter phase shift value corresponding to each micro-ring in the cascade filter. Wherein for a fixed coordinate transformation matrix and a fixed step size, phiiIs also fixed, and to satisfy the effectiveness of the (AD/DA) conversion circuit, the phiiIs a noise value that cannot be less than the entire cascaded filter circuitry. Further, the phi isiThe value also defines the value of the preset step or the selection of the coordinate matrix. I.e. the value of the preset step size or the selection of the coordinate transformation matrix needs to be such that phiiIs greater than or equal to the noise level of the circuitry of the cascaded filter.
Optionally, the wavelength locking device may select the first coordinate transformation matrix according to a preset condition, where the preset condition includes at least one of: each element in the first coordinate transformation matrix is symmetrical based on a zero point; absolute values of all elements in the first coordinate transformation matrix are smaller than a preset value; each element in the first coordinate transformation matrix is relatively single. For example, each element of the first coordinate transformation matrix may be (0, -1, 1).
Optionally, a specific process of the wavelength locking apparatus selecting a target intermediate variable from the intermediate variable combination for iterative feedback may be as follows:
after receiving the incident optical signal, the wavelength locking device records a first power value of the cascade filter, namely the first power value is an initial power value; then the wavelength locking device selects a first intermediate variable from the intermediate variable combination as the target intermediate variable; then the wavelength locking device adjusts the first intermediate variable into a second intermediate variable according to the first preset step length, the first coordinate transformation matrix and the first adjusting mode, and records a second power value of the cascade filter at the moment, wherein the first adjusting mode is used for indicating an increasing or decreasing symbol of the first intermediate variable; then the wavelength locking device determines a second adjustment mode of the second intermediate variable according to the first power value and the second power value, wherein the second adjustment mode is used for indicating an increase/decrease sign of the second intermediate variable; finally, the wavelength locking device adjusts the second intermediate variable into a third intermediate variable according to the first preset step length, the first coordinate transformation matrix and the second adjustment mode, and records a third power value of the cascade filter at the moment; the wavelength locker then performs iterative feedback in turn until the power level of the cascaded filter is stable and at a maximum (also said to be the case when the waveform diagram of the cascaded filter is stable and symmetric). It is understood that the target intermediate variable may include at least one intermediate variable of the combination of intermediate variables, i.e., the wavelength locker may adjust one intermediate variable or may select two or more intermediate variables, which is not limited herein. Here, the iterative feedback is illustrated by selecting two intermediate variables, and it is assumed that the intermediate variable combination includes 4 intermediate variables, PP1, PP2, PP3, and PP 4. After the wavelength locking device receives the incident light signal, recording an initial power value X of the cascade filter; the wavelength locker then selects PP1 and PP2 from the intermediate variable combination as the target intermediate variable; then the wavelength locking device increases the PP1 by the first preset step length to obtain an updated PP1, and at this time, the power value of the cascade filter is recorded as Y; the wavelength locking device increases the PP2 by the first preset step length to obtain an updated PP2, and at this time, the power value of the cascade filter is recorded as Z; then the wavelength locking device compares the X with the Y to obtain the updated adjusting mode of the PP 1; the wavelength locking device compares the Y with the Z to obtain the updated adjustment mode of the PP 2; finally, the wavelength locking device adjusts the updated PP1 again according to the adjustment mode of the updated PP1 and records a new power value A; the wavelength locker readjusts the updated PP2 according to the adjustment method of the updated PP2, and records a new power value B. Namely, the wavelength locking device can sequentially and circularly perform iterative feedback updating until the power value of the cascade filter is stable and the value is maximum, and then the iterative updating is stopped.
Optionally, after the wavelength locking device records the first power value and the second power value, the following technical scheme may be implemented: the wavelength locking device determines a second preset step length according to the first power value and the second power value; and then the wavelength locking device adjusts the second intermediate variable to a fourth intermediate variable according to the second preset step length, the first coordinate transformation matrix and the second adjustment mode, and records a fourth power value of the cascade filter corresponding to the fourth intermediate variable. Wherein, the wavelength locking device determines the second preset step size according to the first power value and the second power value by the following method: the wavelength locking device presets a preset threshold value of the power change rate; then the wavelength locking device calculates a power change rate according to the first power value and the second power value, if the power change rate is greater than the preset threshold, the wavelength locking device determines that the power of the cascade filter is converging towards a steady state, and at the moment, the wavelength locking device determines that the second preset step length is greater than the first preset step length; if the power change rate is smaller than the preset threshold, the wavelength locking device determines that the power of the cascade filter tends to a stable equilibrium state, and at the moment, the wavelength locking device determines that the second preset step length is smaller than the first preset step length. Therefore, the wavelength locking device can automatically reduce the step length in a stable balanced state, and automatically increase the step length to obtain stable balance when the wavelength locking device is in an unbalanced state under the influence of external environment temperature change or large wavelength change, so that the power convergence speed and precision of the cascade filter are further improved.
Optionally, after the wavelength locking device records the first power value and the second power value, the following technical scheme may be implemented: the wavelength locking device determines a second coordinate transformation matrix according to the first power value and the second power value; and then the wavelength locking device adjusts the second intermediate variable to a fifth intermediate variable according to the first preset step length, the second coordinate transformation matrix and the second adjustment mode, and records a fifth power value of the cascade filter corresponding to the fifth intermediate variable. Wherein, the wavelength locking device determines the second coordinate transformation matrix according to the first power value and the second power value in the following manner: the wavelength locking device presets a preset threshold value of the power change rate; then the wavelength locking device calculates a power change rate according to the first power value and the second power value, if the power change rate is larger than the preset threshold value, the wavelength locking device determines that the power of the cascade filter is converging towards a steady state, and at the moment, the wavelength locking device determines that the matrix condition number of the second coordinate transformation matrix is larger than the matrix condition number of the first coordinate transformation matrix; if the power change rate is smaller than the preset threshold value, the wavelength locking device determines that the power of the cascade filter tends to a stable equilibrium state, and at the moment, the wavelength locking device determines that the matrix condition number of the second coordinate transformation matrix is smaller than the matrix condition number of the first coordinate transformation matrix. Therefore, the wavelength locking device can automatically reduce the matrix condition number of the coordinate transformation matrix in a stable balanced state, and automatically increase the matrix condition number of the coordinate transformation matrix to obtain stable balance when the non-balanced state is influenced by external environment temperature change or larger wavelength change, so that the power convergence speed and the precision of the cascade filter are further improved.
Optionally, a specific manner of determining, by the wavelength locking device, the second adjustment manner of the second intermediate variable according to the first power value and the second power value may be as follows: if the second power value is smaller than the first power value, the wavelength locking device determines that the increase or decrease signs of the second adjustment mode of the second intermediate variable are opposite to the increase or decrease signs of the first adjustment mode; if the second power value is greater than the first power value, the wavelength locking device determines that the second adjustment mode of the second intermediate variable is the same as the first adjustment mode in increasing or decreasing signs. Specifically, if the power value obtained after changing an intermediate variable is found to be greater than the initial power value, it is proved that the step-increasing operation in the direction can make the power value become larger, that is, the resonance peak of the lower spectral line moves around the wavelength of the target filtering, and then the step-increasing operation should be continued in the direction for the intermediate variable; if the power value obtained after changing a certain intermediate variable is found to be smaller than the initial power value, it is proved that the operation of increasing the step size in the direction instead makes the power smaller, that is, the resonance peak of the lower spectral line shifts the wavelength of the target filtering, at this moment, the sign of the step size increase should be changed, and the negative increase of the step size should be performed in the next cycle corresponding to the intermediate variable. This can make the power convergence speed of the cascade filter faster.
In a second aspect, embodiments of the present application provide a wavelength locker having functionality for performing the behavior of the wavelength locker of the first aspect. The functions can be realized by hardware, and the functions can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the above-described functions.
In one possible implementation, the apparatus includes means or modules for performing the steps of the first aspect above. For example, the apparatus includes: the acquisition module is used for acquiring an incident light signal; a processing module, configured to load an initial voltage value combination for a cascade filter according to a lookup table and a target filtering wavelength, where the lookup table is used to indicate a mapping relationship between a filtering wavelength and a voltage value of the cascade filter, the cascade filter includes N rings, the initial voltage value combination includes N initial voltage values, the target filtering is an output optical signal of the cascade filter, and N is an integer greater than or equal to 2; generating an intermediate variable combination according to a first coordinate transformation matrix and the initial voltage value combination, wherein the first coordinate transformation matrix is an Nx-Nth order matrix; selecting a target intermediate variable from the intermediate variable combination to perform iterative feedback by using a first preset step length and the first coordinate transformation matrix, and recording a power value of the cascade filter;
and the output module is used for filtering the target filter from the incident light signal when the power value is maximum.
Optionally, the apparatus further comprises a storage module for storing necessary program instructions and data of the wavelength locking device.
In one possible implementation, the apparatus includes: a processor, a transceiver and a memory, the processor being configured to support a wavelength locker to perform the respective functions of the method provided by the first aspect; the memory is configured to be coupled to the processor for storing necessary program instructions and data for the wavelength locker.
In one possible implementation, when the device is a chip within a wavelength-locking device, the chip includes: a processing module and a transceiver module, the processing module may be, for example, a processor, and the processor is configured to load an initial voltage value combination for a cascaded filter according to a lookup table and a target filtered wavelength, the lookup table is used to indicate a mapping relationship between a filtered wavelength and a voltage value of the cascaded filter, the cascaded filter includes N rings, the initial voltage value combination includes N initial voltage values, the target filter is an output optical signal of the cascaded filter, and N is an integer greater than or equal to 2; generating an intermediate variable combination according to a first coordinate transformation matrix and the initial voltage value combination, wherein the first coordinate transformation matrix is an Nx-Nth order matrix; selecting a target intermediate variable from the intermediate variable combination to perform iterative feedback by using a first preset step length and the first coordinate transformation matrix, and recording a power value of the cascade filter; the transceiver module may be, for example, an input/output interface, pin, or circuit on the chip, and receives the incident optical signal or transmits the target filter filtered by the processor to another chip or module coupled to the chip. The processing module may execute computer executable instructions stored by the memory unit to enable the wavelength locker to perform corresponding functions as described above in relation to the method of the first aspect. Alternatively, the storage unit may be a storage unit in the chip, such as a register, a cache, and the like, and the storage unit may also be a storage unit located outside the chip, such as a read-only memory (ROM) or another type of static storage device that can store static information and instructions, a Random Access Memory (RAM), and the like.
In one possible implementation, the apparatus includes: a processor, baseband circuitry, radio frequency circuitry, and an antenna. Wherein the processor is used for realizing the control of the functions of each circuit part. Optionally, the apparatus further comprises a memory that holds necessary program instructions and data for the wavelength locker.
The processor mentioned in any of the above paragraphs may be a general purpose Central Processing Unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of programs for controlling the method of coordinated allocation of channel resources in the above paragraphs.
In a third aspect, an embodiment of the present application provides a computer-readable storage medium, where computer instructions are stored, and the computer instructions are configured to execute the method described in any possible implementation manner in the first aspect.
In a fourth aspect, the present application provides a computer program product containing instructions, which when run on a computer, cause the computer to perform the method described in any of the possible embodiments of the first aspect of the above aspects.
In a fifth aspect, the present application provides a chip system comprising a processor for enabling a wavelength locker to perform the functions referred to in the above aspects, such as generating or processing data and/or information referred to in the above methods. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the wavelength locker to function in any of the above aspects. The chip system may be formed by a chip, and may also include a chip and other discrete devices.
Drawings
FIG. 1 is a schematic diagram of a cascaded filter structure;
FIG. 2 is a schematic flow chart of a feedback control method for a double-loop cascade micro-loop filter;
FIG. 3 is a diagram of an architecture of an application of the wavelength locking method in an embodiment of the present application;
FIG. 4 is a schematic diagram of an embodiment of a wavelength locking method in an embodiment of the present application;
FIG. 5 is a flowchart illustrating a wavelength locking method according to an embodiment of the present application;
FIG. 6 is a schematic flow chart of a wavelength locking method according to an embodiment of the present application;
FIG. 7 is a schematic diagram of an embodiment of a wavelength locker in an embodiment of the present application;
fig. 8 is a schematic diagram of another embodiment of a wavelength locker in an embodiment of the present application.
Detailed Description
The embodiment of the application provides a wavelength locking method and a wavelength locking device, which are used for improving the accuracy of wavelength locking of a high-order micro-ring.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the present application and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In a conventional optical communication system, precision of uploading and downloading of optical wavelengths is required to be high in a metropolitan area network node. The optical filter is essential to select the optical wavelength, and when a series of optical signals come in at the receiving end, the optical filter needs to selectively download and upload the specified optical signals to the optical wavelength. An optical filter may be composed of cascaded micro-rings, or may be composed of cascaded structures such as MZI. Since the interval of the incident light wavelength is small for the optical filter, the wavelength point of the lower wave must be accurate to the range of 1nm, and the corresponding wavelength of the lower wave should be kept constant in response to the external environment change in order to make the performance thereof superior. The cascade micro-loop filter can stabilize the resonance peak of the cascade micro-loop filter in a dynamic balance state through continuous feedback control by a feedback system such as that shown in fig. 1. However, the present invention only provides a feedback control method for a dual-loop cascade micro-loop filter. As shown in fig. 2, for the two-loop cascade filter, the phases corresponding to the two loops are represented by the intermediate variable, two-loop phase sum and two-loop phase difference, where the two-loop phase sum is Φavg＝(φ1+φ2) A phase difference between the two rings of phidiff＝(φ1-φ2) /2, wherein phi1Phase shift around the first micro-Ring (RTPS), phi2The RTPS for the second micro-ring. Phi is aavgAnd phidiffIs zero for phi in each iterationavgOr phidiffThe value of (1) is increased by a variable of a small step length so as to change the voltage on two rings at a time, then the reading value of an off-chip Photodetector (PD) is detected, whether the PD value is increased or decreased compared with the last time is compared, and then the judgment and feedback are carried out to continue to increase or decrease phiavgOr phidiffThe value of (2) achieves the purpose of changing the phase positions on the two micro-rings, thereby achieving the effect of voltage linkage of the two rings. However, as communication systems are developed, the Free Spectral Range (FSR) of the filter is also increased, and therefore, the filter mostly adopts a high-order micro-ring filter with vernier effect or a cascaded MZI filter. While having vernier effectThe sensitivity of the order micro-ring filter or the cascade MZI filter to the wavelength is higher, and due to the interference of the severe change of the external environment temperature, the jump, the jitter, the drift and the like of the wavelength, the error caused by the inaccurate wavelength of each ring resonance peak is increased exponentially. Therefore, the method of converting the voltage on the ring and the phase difference between the ring and the two rings is not suitable for the locking control of the high-order micro-ring.
In order to solve this problem, an embodiment of the present application provides a wavelength locking method, which is applied to a cascaded filter including N rings, where N is an integer greater than or equal to 2, and specifically includes: the wavelength locking device establishes a lookup table for indicating the corresponding relation of the filtering wavelength of the cascade filter and the voltage value combination of the cascade filter; then, under the condition that the wavelength locking device acquires an incident light signal and determines the wavelength of the target filtering of the cascade filter, the wavelength locking device loads an initial voltage value combination for the cascade filter; the wavelength locking device determines an intermediate variable combination according to a coordinate transformation matrix and the initial voltage value combination, wherein the coordinate transformation matrix is an N x N matrix; the wavelength locking device adjusts at least one intermediate variable in the intermediate variable combination according to a first preset step length to carry out iterative feedback adjustment, and records the adjusted power value of the cascade filter; the wavelength locker outputs the target filter from the incident optical signal when the power value of the cascade filter is maximum.
In the embodiment of the present application, taking a cascaded four-micro-ring filter as an example, an application architecture of the wavelength locking method may be as shown in fig. 3: the left side of fig. 3 is a cascaded four-micro loop filter, which is composed of 4 micro loops (V4, V3, V2, V1, respectively) connected In series and has four ports, In, thr, Add, Drop, respectively. The In port receives an incident light signal, and the Drop port outputs a target for filtering. The filtering spectral lines of all the micro-rings are different, and the filtering spectral lines of all the micro-rings can be moved left and right by heating the micro-rings through metal layer heaters (heater) designed on the micro-rings. The Drop port is connected with a Photodetector (PD), and the PD can record a power value of the cascaded four-micro-ring filter and feed the power value back to the wavelength locking module. Wherein the wavelength locking module is composed of a Coordinate transformation Matrix (TCM), and the wavelength locking module may further include a Step Adaptive module (Adaptive Step).
In this embodiment, the wavelength locking device may be integrated with the cascade filter into an integral device, that is, the cascade filter includes the wavelength locking device, so as to implement the wavelength locking function; the wavelength locking device may also be a separate device from the cascaded filter, and is not limited herein.
Specifically, referring to fig. 4, an embodiment of a wavelength locking method in the embodiment of the present application includes:
401. the wavelength locker receives an incident optical signal.
The cascade filter receives an incident optical signal to activate the wavelength locking device to start operation.
It is understood that the wavelength locking device can be directly the cascaded filter, i.e. the cascaded filter has the function of wavelength locking, or the wavelength locking device is a separate physical device connected to the cascaded filter, so as to control the cascaded filter.
402. The wavelength locking device determines a target filtering of the cascade filter and obtains a wavelength of the target filtering.
The wavelength locking device determines the target filtering to be output by the cascade filter and obtains the wavelength of the target filtering. That is, for example, at the present moment, the cascade filter needs to be filtered next by a target with a wavelength λ, and the wavelength locking device needs to know the wavelength.
403. The wavelength locking device loads an initial voltage value combination for a cascade filter according to the wavelength of the target filtering and a lookup table, wherein the cascade filter comprises N rings, and N is an integer greater than or equal to 2.
Before the wavelength locking device operates, a lookup table for indicating the corresponding relationship between the filtering wavelength of the cascade filter and the voltage value combination of the cascade filter is established for the cascade filter (namely, the wavelength locking device can filter the incident light signal received by the cascade filter by the designated wavelength through the lookup table); the wavelength locker then loads an initial voltage value for the cascaded filter based on the filter length of the target filter and the look-up table.
It can be understood that after the cascade filter is loaded with the initial voltage value, the initial voltage value cannot accurately filter the incident light signal because the metal layer heater on the ring is a thermal modulator, which causes the micro-rings to have serious crosstalk with each other, and the temperature of the surrounding environment is not constant.
404. The wavelength locking device generates an intermediate variable combination according to a first coordinate transformation matrix and the initial voltage value, wherein the first coordinate transformation matrix is an N-by-N matrix.
The wavelength locking device selects the first coordinate transformation matrix according to a preset condition based on a matrix condition number, wherein the matrix condition number is within a preset range; and finally, the wavelength locking device generates the intermediate variable combination by using a matrix equation according to the first coordinate transformation matrix and the initial voltage value combination. Wherein the matrix equation is PPi＝A*φi(ii) a I is equal to N, PPiFor the intermediate variable, the A is the first coordinate transformation matrix, the phiiAnd the jitter voltage value is between the initial voltage value and a target voltage value, and the target voltage value is a voltage value loaded when the cascade filter is stable. For example, if the cascaded filter includes 4 micro-loops, the matrix equation is PPi＝A*φi(i ═ 1,2,3, 4). That is, the intermediate variables after coordinate transformation matrix can be as follows:
PP1＝A*φ1+A*φ2+A*φ3+A*φ4；
PP2＝A*φ1+A*φ2+A*φ3+A*φ4；
PP3＝A*φ1+A*φ2+A*φ3+A*φ4；
PP4＝A*φ1+A*φ2+A*φ3+A*φ4；
in practical cases, each micro-ring is subjected to a corresponding voltage value, and each micro-ring corresponds to a corresponding phase shift around the ring. Due to the process tolerance, the micro-ring has a certain deviation between the winding phase shift loaded according to the lookup table and the ideal phase shift, so the voltage value on the micro-ring needs to be adjusted correspondingly, that is, the winding phase shift of the micro-ring is adjusted correspondingly1,φ2,φ3,φ4And the jitter phase shift value corresponding to each micro-ring in the cascade filter. Wherein for a fixed coordinate transformation matrix and a fixed step size, phiiIs also fixed, and to satisfy the effectiveness of the (AD/DA) conversion circuit, the phiiIs a noise value that cannot be less than the entire cascaded filter circuitry. Further, the phi isiThe value also defines the value of the preset step or the selection of the coordinate matrix. I.e. the value of the preset step size or the selection of the coordinate transformation matrix needs to be such that phiiIs greater than or equal to the noise level of the circuitry of the cascaded filter.
The wavelength locking device may select the first coordinate transformation matrix according to a preset condition, where the preset condition includes at least one of: each element in the first coordinate transformation matrix is symmetrical based on a zero point; absolute values of all elements in the first coordinate transformation matrix are smaller than a preset value; each element in the first coordinate transformation matrix is relatively single. For example, each element of the first coordinate transformation matrix may be (0, -1, 1).
405. The wavelength locking device selects a target intermediate variable from the intermediate variable combination for iterative feedback, and records the adjusted power value of the cascade filter.
In this embodiment, after receiving the incident optical signal, the wavelength locking device records a first power value of the cascade filter, that is, the first power value is an initial power value; then the wavelength locking device selects a first intermediate variable from the intermediate variable combination as the target intermediate variable; then the wavelength locking device adjusts the first intermediate variable into a second intermediate variable according to the first preset step length, the first coordinate transformation matrix and the first adjusting mode, and records a second power value of the cascade filter at the moment, wherein the first adjusting mode is used for indicating an increasing or decreasing symbol of the first intermediate variable; then the wavelength locking device determines a second adjustment mode of the second intermediate variable according to the first power value and the second power value, wherein the second adjustment mode is used for indicating an increase/decrease sign of the second intermediate variable; finally, the wavelength locking device adjusts the second intermediate variable into a third intermediate variable according to the first preset step length, the first coordinate transformation matrix and the second adjustment mode, and records a third power value of the cascade filter at the moment; the wavelength locker then performs iterative feedback in turn until the power level of the cascaded filter is stable and at a maximum (also said to be the case when the waveform diagram of the cascaded filter is stable and symmetric). It is understood that the target intermediate variable may include at least one intermediate variable of the combination of intermediate variables, i.e., the wavelength locker may adjust one intermediate variable or may select two or more intermediate variables, which is not limited herein. Here, the iterative feedback is illustrated by selecting two intermediate variables, and it is assumed that the intermediate variable combination includes 4 intermediate variables, PP1, PP2, PP3, and PP 4. After the wavelength locking device receives the incident light signal, recording an initial power value X of the cascade filter; the wavelength locker then selects PP1 and PP2 from the intermediate variable combination as the target intermediate variable; then the wavelength locking device increases the PP1 by the first preset step length to obtain an updated PP1, and at this time, the power value of the cascade filter is recorded as Y; the wavelength locking device increases the PP2 by the first preset step length to obtain an updated PP2, and at this time, the power value of the cascade filter is recorded as Z; then the wavelength locking device compares the X with the Y to obtain the updated adjusting mode of the PP 1; the wavelength locking device compares the Y with the Z to obtain the updated adjustment mode of the PP 2; finally, the wavelength locking device adjusts the updated PP1 again according to the adjustment mode of the updated PP1 and records a new power value A; the wavelength locker readjusts the updated PP2 according to the adjustment method of the updated PP2, and records a new power value B. Namely, the wavelength locking device can sequentially and circularly perform iterative feedback updating until the power value of the cascade filter is stable and the value is maximum, and then the iterative updating is stopped.
Optionally, a specific manner of determining, by the wavelength locking device, the second adjustment manner of the second intermediate variable according to the first power value and the second power value may be as follows: if the second power value is smaller than the first power value, the wavelength locking device determines that the increase or decrease signs of the second adjustment mode of the second intermediate variable are opposite to the increase or decrease signs of the first adjustment mode; if the second power value is greater than the first power value, the wavelength locking device determines that the second adjustment mode of the second intermediate variable is the same as the first adjustment mode in increasing or decreasing signs. Specifically, if the power value obtained after changing an intermediate variable is found to be greater than the initial power value, it is proved that the step-increasing operation in the direction can make the power value become larger, that is, the resonance peak of the lower spectral line moves around the wavelength of the target filtering, and then the step-increasing operation should be continued in the direction for the intermediate variable; if the power value obtained after changing a certain intermediate variable is found to be smaller than the initial power value, it is proved that the operation of increasing the step size in the direction instead makes the power smaller, that is, the resonance peak of the lower spectral line shifts the wavelength of the target filtering, at this moment, the sign of the step size increase should be changed, and the negative increase of the step size should be performed in the next cycle corresponding to the intermediate variable. This can make the power convergence speed of the cascade filter faster.
In this embodiment, the wavelength locking device may further perform adaptive step size adjustment during iterative feedback, that is, the wavelength locking device determines a second preset step size according to the first power value and the second power value; and then the wavelength locking device adjusts the second intermediate variable to a fourth intermediate variable according to the second preset step length, the first coordinate transformation matrix and the second adjustment mode, and records a fourth power value of the cascade filter corresponding to the fourth intermediate variable. The example is illustrated with the cascaded four micro-loop filter shown in fig. 3 and with two intermediate variables adjusted (PP 1 and PP 2). Specifically, referring to fig. 5, a schematic flow chart of a wavelength locking method in an embodiment of the present application includes:
the wavelength locking device loads initial voltage values for the four micro-rings of the cascade filter through a lookup table; then, when the cascade filter receives an incident light signal, the PD connected with the Drop port of the cascade filter acquires an initial power value X of the cascade filter; the wavelength locker then sets a preset target power value, which is understood to be greater than the optical power output by the Drop port, thus ensuring that the iterative feedback control process of the wavelength locker continues. The wavelength locking device sets a first preset step length; then the wavelength locking device increases the first preset step size for the PP1, and records the power value at this time as Y; the wavelength locker increments the PP2 by the first preset step size and records the power value at this time as Z. After these two step adjustments, the voltage values on the four microrings change accordingly. Then the wavelength locking device compares the power value Y with the power value X, and compares the power value Z with the power value Y; if Y is greater than X, it means that increasing the step size on the PP1 can make the power value of the cascade filter become larger, i.e. the resonance peak of the lower spectral line moves to the vicinity of the target filtering wavelength, then the step size can be continuously increased for the PP1 in the next adjustment process; if Y is smaller than X, it indicates that increasing the first step size to the PP1 can decrease the power value of the cascade filter, i.e. the resonance peak of the lower spectral line is far away from the target filtering wavelength, then the first preset step size can be subtracted from the PP1 in the next adjustment process; if Z is greater than Y, it indicates that increasing the step size on the PP2 can make the power value of the cascade filter become larger, i.e. the resonance peak of the lower spectral line moves to the vicinity of the target filtering wavelength, then the first preset step size can be continuously increased for the PP2 in the next adjustment process; if Z is smaller than Y, it means that the power value of the cascade filter can be decreased by adding the first preset step to PP2, that is, the resonant peak of the lower spectral line is far away from the target filtering wavelength, and then the first preset step can be subtracted from PP2 in the next adjustment process; meanwhile, the wavelength locking device calculates the power change rate after the iteration according to the power values Z and X; the wavelength locking device judges the relation between the power change rate and a preset threshold value, if the power change rate is larger than the preset threshold value, the cascade filter is shown to be converging towards a steady state, and at the moment, the wavelength locking device can accelerate the convergence speed of the cascade filter so as to adjust the step length, so that the second preset step length of the next iteration is larger than the first preset step length; if the power change rate is smaller than the preset threshold, it indicates that the cascade filter has already approached a stable equilibrium state, and at this time, the wavelength locking device needs to ensure the correctness of convergence, so as to adjust the step length, so that the second preset step length of the next iteration is smaller than the first preset step length; the wavelength locking device then repeats the iterative feedback process according to the following steps, and ends the iterative process when the power value of the cascaded filter is stable.
Optionally, the wavelength locking device may further perform adaptive adjustment of a coordinate transformation matrix, that is, the wavelength locking device determines a second coordinate transformation matrix according to the first power value and the second power value; and then the wavelength locking device adjusts the second intermediate variable to a fifth intermediate variable according to the first preset step length, the second coordinate transformation matrix and the second adjustment mode, and records a fifth power value of the cascade filter corresponding to the fifth intermediate variable. The example is illustrated with the cascaded four micro-loop filter shown in fig. 3 and with two intermediate variables adjusted (PP 1 and PP 2). Specifically, referring to fig. 6, a schematic flow chart of a wavelength locking method in an embodiment of the present application includes:
the wavelength locking device loads initial voltage values for the four micro-rings of the cascade filter through a lookup table; then, when the cascade filter receives an incident light signal, the PD connected with the Drop port of the cascade filter acquires an initial power value X of the cascade filter; the wavelength locker then sets a preset target power value, which is understood to be greater than the optical power output by the Drop port, thus ensuring that the iterative feedback control process of the wavelength locker continues. The wavelength locking device sets a first preset step length; then the wavelength locking device increases the first preset step size for the PP1, and records the power value at this time as Y; the wavelength locker increments the PP2 by the first preset step size and records the power value at this time as Z. After these two step adjustments, the voltage values on the four microrings change accordingly. Then the wavelength locking device compares the power value Y with the power value X, and compares the power value Z with the power value Y; if Y is greater than X, it means that increasing the step size on the PP1 can make the power value of the cascade filter become larger, i.e. the resonance peak of the lower spectral line moves to the vicinity of the target filtering wavelength, then the step size can be continuously increased for the PP1 in the next adjustment process; if Y is smaller than X, it indicates that increasing the first step size to the PP1 can decrease the power value of the cascade filter, i.e. the resonance peak of the lower spectral line is far away from the target filtering wavelength, then the first preset step size can be subtracted from the PP1 in the next adjustment process; if Z is greater than Y, it indicates that increasing the step size on the PP2 can make the power value of the cascade filter become larger, i.e. the resonance peak of the lower spectral line moves to the vicinity of the target filtering wavelength, then the first preset step size can be continuously increased for the PP2 in the next adjustment process; if Z is smaller than Y, it means that the power value of the cascade filter can be decreased by adding the first preset step to PP2, that is, the resonant peak of the lower spectral line is far away from the target filtering wavelength, and then the first preset step can be subtracted from PP2 in the next adjustment process; meanwhile, the wavelength locking device calculates the power change rate after the iteration according to the power values Z and X; the wavelength locking device judges the relation between the power change rate and a preset threshold value, if the power change rate is larger than the preset threshold value, the cascade filter is shown to be converging towards a steady state, and at the moment, the wavelength locking device can accelerate the convergence speed of the cascade filter, so that a coordinate transformation matrix is updated, and the condition number of a second matrix of a second coordinate transformation matrix of the next iteration is larger than the condition number of a first matrix of the first coordinate transformation matrix; if the power change rate is smaller than the preset threshold, the cascade filter tends to be in a stable balance state, and at the moment, the wavelength locking device needs to ensure the accuracy of convergence, so that the coordinate transformation matrix is updated, and the second matrix condition number of the second coordinate transformation matrix of the next iteration is smaller than the first matrix condition number of the first coordinate transformation matrix; the wavelength locking device then repeats the iterative feedback process according to the following steps, and ends the iterative process when the power value of the cascaded filter is stable.
406. The wavelength locker outputs the target filter from the incident optical signal when the power value is a maximum value.
When the power value of the cascade filter is the maximum value, the wavelength locking device determines that the waveform diagram of the cascade filter at the wavelength of the target filtering is stable and meets the requirement, and then the wavelength locking device determines that the iterative feedback adjustment is finished, so that the cascade filter can filter the target filtering from the incident light signal.
The wavelength locking device generates an intermediate variable by utilizing a coordinate transformation matrix and carries out iterative feedback in a linkage manner, so that the wavelength locking precision is higher, the response to the influence of the external environment is quicker, and the excellent judgment of the locking state becomes more accurate and excellent. Meanwhile, the wavelength locking device can automatically reduce the step length or the matrix condition number of the coordinate transformation matrix in a stable balanced state, and automatically increase the step length or the matrix condition number of the coordinate transformation matrix in an unbalanced state under the influence of the change of the external environment temperature or the change of a larger wavelength to obtain stable balance, so that the power convergence speed and the precision of the cascade filter are further improved.
The wavelength locking method in the embodiment of the present application is described above, and the wavelength locking device in the embodiment of the present application is described below.
Specifically, referring to fig. 7, the wavelength locking device 700 according to the embodiment of the present application includes: an obtaining module 701, a processing module 702 and an output module 703. The apparatus 700 may be one or more chips or other possible physical devices. The apparatus 700 may be used to perform some or all of the functions of the wavelength locker apparatus in the method embodiments described above.
For example, the obtaining module 701 may be configured to execute step 401 in the foregoing method embodiment. For example, the acquisition module 701 acquires an incident light signal;
the processing module 702 may be configured to perform steps 402 to 405 in the above-described method embodiments. For example, the processing module 702 loads an initial voltage value combination for the cascaded filter according to a lookup table and a target filtered wavelength, the lookup table being used for indicating a mapping relationship between the filtered wavelength and a voltage value of the cascaded filter, the cascaded filter including N rings, the initial voltage value combination including N initial voltage values, the target filtered being an output optical signal of the cascaded filter, N being an integer greater than or equal to 2; generating an intermediate variable combination according to a first coordinate transformation matrix and the initial voltage value combination, wherein the first coordinate transformation matrix is an Nx-Nth order matrix; selecting a target intermediate variable from the intermediate variable combination to perform iterative feedback by using a first preset step length and the first coordinate transformation matrix, and recording a power value of the cascade filter;
the output module 703 may be configured to execute step 406 in the foregoing method embodiment. For example, the output module 703 filters the target filter from the incident optical signal when the power value is maximum.
Optionally, the wavelength locking device 700 may further include a storage module coupled to the processing module, so that the processing module may execute computer-executable instructions stored in the storage module to implement the functions of the wavelength locking device in the above-described method embodiments. In an example, the storage module optionally included in the apparatus 700 may be a storage unit inside the chip, such as a register, a cache, or the like, and the storage module may also be a storage unit located outside the chip, such as a read-only memory (ROM) or another type of static storage device that can store static information and instructions, a Random Access Memory (RAM), or the like.
It should be understood that the flow executed between the modules of the wavelength locker in the corresponding embodiment of fig. 7 is similar to the flow executed by the wavelength locker in the corresponding method embodiments of fig. 4 to fig. 6, and detailed description thereof is omitted here.
Fig. 8 shows a possible structure diagram of a wavelength locker 800 in the above embodiment, and the wavelength locker 800 may be configured as the wavelength locker. The apparatus 800 may include: a processor 802, a computer-readable storage medium/memory 803, a transceiver 804, an input device 805, and an output device 806, and a bus 801. Wherein the processor, transceiver, computer readable storage medium, etc. are connected by a bus. The embodiments of the present application do not limit the specific connection medium between the above components.
In one example, the transceiver 804 acquires an incident optical signal;
the processor 802 loads an initial voltage value combination for a cascade filter according to a lookup table and a target filtering wavelength, where the lookup table is used to indicate a mapping relationship between a filtering wavelength and a voltage value of the cascade filter, the cascade filter includes N rings, the initial voltage value combination includes N initial voltage values, the target filtering is an output optical signal of the cascade filter, and N is an integer greater than or equal to 2; generating an intermediate variable combination according to a first coordinate transformation matrix and the initial voltage value combination, wherein the first coordinate transformation matrix is an Nx-Nth order matrix; selecting a target intermediate variable from the intermediate variable combination to perform iterative feedback by using a first preset step length and the first coordinate transformation matrix, and recording a power value of the cascade filter;
the transceiver 804 filters the target filter from the incoming optical signal when the power value is at a maximum.
In yet another example, the processor 802 may run an operating system that controls functions between various devices and appliances. The transceiver 804 may include baseband circuitry and radio frequency circuitry.
The transceiver 804 and the processor 802 may implement corresponding steps in any of the embodiments of fig. 4 to fig. 6, which are not described herein in detail.
It is understood that fig. 8 only shows a simplified design of the wavelength locker, and in practical applications, the wavelength locker may comprise any number of transceivers, processors, memories, etc., and all wavelength lockers that may implement the present application are within the scope of the present application.
The processor 802 involved in the apparatus 800 may be a general-purpose processor, such as a Central Processing Unit (CPU), a Network Processor (NP), a microprocessor, etc., or an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the program according to the present disclosure. But also a Digital Signal Processor (DSP), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components. The controller/processor can also be a combination of computing functions, e.g., comprising one or more microprocessors, DSPs, and microprocessors, among others. Processors typically perform logical and arithmetic operations based on program instructions stored within memory.
The bus 801 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 8, but this is not intended to represent only one bus or type of bus.
The computer-readable storage medium/memory 803 referred to above may also hold an operating system and other application programs. In particular, the program may include program code including computer operating instructions. More specifically, the memory may be a read-only memory (ROM), other types of static storage devices that may store static information and instructions, a Random Access Memory (RAM), other types of dynamic storage devices that may store information and instructions, a disk memory, and so forth. The memory 803 may be a combination of the above memory types. And the computer-readable storage medium/memory described above may be in the processor, may be external to the processor, or distributed across multiple entities including the processor or processing circuitry. The computer-readable storage medium/memory described above may be embodied in a computer program product. By way of example, a computer program product may include a computer-readable medium in packaging material.
Alternatively, embodiments of the present application also provide a general-purpose processing system, such as that commonly referred to as a chip, including one or more microprocessors that provide processor functionality; and an external memory providing at least a portion of the storage medium, all connected together with other supporting circuitry through an external bus architecture. The memory stores instructions that, when executed by the processor, cause the processor to perform some or all of the steps of the wavelength locking apparatus in the wavelength locking methods of the embodiments described in fig. 4-6 and/or other processes for the techniques described herein.
The steps of a method or algorithm described in connection with the disclosure herein may be embodied in hardware or in software instructions executed by a processor. The software instructions may consist of corresponding software modules that may be stored in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such 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 wavelength locker assembly. Of course, the processor and the storage medium may reside as discrete components in a wavelength locker apparatus.
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 manners. 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 integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit 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 may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes 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: a U-disk, a removable hard disk, a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.

Claims (21)

1. A method of wavelength locking, comprising:
the wavelength locking device acquires an incident light signal;
the wavelength locking device loads an initial voltage value combination for a cascade filter according to a lookup table and a target filtering wavelength, wherein the lookup table is used for indicating a mapping relation between a filtering wavelength and a voltage value of the cascade filter, the cascade filter comprises N rings, N is an integer greater than or equal to 2, the initial voltage value combination comprises N initial voltage values, and the target filtering is an output optical signal of the cascade filter;
the wavelength locking device generates an intermediate variable combination according to a first coordinate transformation matrix and the initial voltage value combination, wherein the first coordinate transformation matrix is an Nx-Nth order matrix;
the wavelength locking device selects a target intermediate variable from the intermediate variable combination to perform iterative feedback by using a first preset step length and the first coordinate transformation matrix, and records the power value of the cascade filter;
the wavelength locker filters the target filter from the incoming optical signal when the power value is at a maximum.
2. The method of claim 1, wherein the wavelength locker generating intermediate variable combinations from the first coordinate transformation matrix and the initial voltage value combinations comprises:
the wavelength locking device selects the first coordinate transformation matrix according to a preset condition, and the matrix condition number of the first coordinate transformation matrix is within a preset range;
the wavelength locking device generates an intermediate variable combination by using a matrix equation according to the first coordinate transformation matrix and the initial voltage value combination;
the matrix equation is: PP (polypropylene)i＝A*φi；
I is equal to N, PPiFor the intermediate variable, the A is the first coordinate transformation matrix, the phiiIs a jitter voltage value between the initial voltage value and a target voltage value, the target voltage value is a voltage value loaded when the cascade filter is stable, phiiIs greater than or equal to a noise value of circuitry of the cascaded filter.
3. The method according to claim 2, wherein the preset conditions include at least one of: each element in the first coordinate transformation matrix is symmetrical based on a zero point; absolute values of all elements in the first coordinate transformation matrix are smaller than a preset value; and the values of all elements in the first coordinate transformation matrix are relatively single.
4. The method of claim 1, wherein the wavelength locker selects a target intermediate variable from the set of intermediate variables for iterative feedback with a first preset step size and the first coordinate transformation matrix, and records the power values of the cascaded filters comprises:
the wavelength locking device records a first power value of the cascade filter when the incident light signal is incident;
the wavelength locking device selects a first intermediate variable from the intermediate variable combination as the target intermediate variable;
the wavelength locking device adjusts the first intermediate variable into a second intermediate variable according to the first preset step length, the first coordinate transformation matrix and a first adjustment mode, and records a second power value of the cascade filter at the moment, wherein the first adjustment mode is used for indicating an increase/decrease sign of the first intermediate variable;
the wavelength locking device determines a second adjustment mode of the second intermediate variable according to the first power value and the second power value, wherein the second adjustment mode is used for indicating an increasing or decreasing symbol of the second intermediate variable;
and the wavelength locking device adjusts the second intermediate variable into a third intermediate variable according to the first preset step length, the first coordinate transformation matrix and the second adjustment mode, and records a third power value of the cascade filter at the moment.
5. The method of claim 4, further comprising:
the wavelength locking device determines a second preset step length according to the first power value and the second power value;
and the wavelength locking device adjusts the second intermediate variable into a fourth intermediate variable according to the second preset step length, the first coordinate transformation matrix and the second adjustment mode, and records a fourth power value of the cascade filter at the moment.
6. The method of claim 5, wherein the wavelength locker determining a second preset step size based on the first power value and the second power value comprises:
the wavelength locking device calculates a power change rate according to the first power value and the second power value;
if the power change rate is greater than a preset threshold, the wavelength locking device determines that the second preset step length is greater than the first preset step length;
if the power change rate is smaller than the preset threshold, the wavelength locking device determines that the second preset step length is smaller than the first preset step length.
7. The method of claim 4, further comprising:
the wavelength locking device determines a second coordinate transformation matrix according to the first power value and the second power value;
and the wavelength locking device adjusts the second intermediate variable into a fifth intermediate variable according to the first preset step length, the second coordinate transformation matrix and the second adjustment mode, and records a fifth power value of the cascade filter at the moment.
8. The method of claim 7, wherein the wavelength locker determines a second coordinate transformation matrix based on the first power value and the second power value comprises:
the wavelength locking device calculates a power change rate according to the first power value and the second power value;
if the first power change rate is larger than a preset threshold value, the wavelength locking device determines that the matrix condition number of the second coordinate transformation matrix is larger than the matrix condition number of the first coordinate transformation matrix;
if the first power change rate is smaller than the preset threshold, the wavelength locking device determines that the matrix condition number of the second coordinate transformation matrix is smaller than the matrix condition number of the first coordinate transformation matrix.
9. The method according to any of claims 4 to 8, wherein the determining by the wavelength locker a second adjustment of the second intermediate variable based on the first power value and the second power value comprises:
if the second power value is smaller than the first power value, the wavelength locking device determines that the increase or decrease signs of the second adjustment mode of the second intermediate variable are opposite to the increase or decrease signs of the first adjustment mode;
if the second power value is greater than the first power value, the wavelength locking device determines that the second adjustment mode of the second intermediate variable is the same as the first adjustment mode in increasing or decreasing signs.
10. A wavelength locker, comprising:
the acquisition module is used for acquiring an incident light signal;
a processing module, configured to load an initial voltage value combination for a cascade filter according to a lookup table and a target filtering wavelength, where the lookup table is used to indicate a mapping relationship between a filtering wavelength and a voltage value of the cascade filter, the cascade filter includes N rings, the initial voltage value combination includes N initial voltage values, the target filtering is an output optical signal of the cascade filter, and N is an integer greater than or equal to 2; generating an intermediate variable combination according to a first coordinate transformation matrix and the initial voltage value combination, wherein the first coordinate transformation matrix is an Nx-Nth order matrix; selecting a target intermediate variable from the intermediate variable combination to perform iterative feedback by using a first preset step length and the first coordinate transformation matrix, and recording a power value of the cascade filter;
and the output module is used for filtering the target filter from the incident light signal when the power value is maximum.
11. The apparatus according to claim 10, wherein the processing module is specifically configured to select the first coordinate transformation matrix according to a preset condition, and a matrix condition number of the first coordinate transformation matrix is within a preset range;
generating an intermediate variable combination by using a matrix equation according to the first coordinate transformation matrix and the initial voltage value combination;
the matrix equation is: PP (polypropylene)i＝A*φi；
I is equal to N, PPiIs the intermediate variable, the A is the secondA coordinate transformation matrix of said phiiIs a jitter voltage value between the initial voltage value and a target voltage value, the target voltage value is a voltage value loaded when the cascade filter is stable, phiiIs greater than or equal to a noise value of circuitry of the cascaded filter.
12. The apparatus according to claim 11, wherein the preset condition comprises at least one of: each element in the first coordinate transformation matrix is symmetrical based on a zero point; absolute values of all elements in the first coordinate transformation matrix are smaller than a preset value; and the values of all elements in the first coordinate transformation matrix are relatively single.
13. The apparatus according to claim 10, wherein the processing module is specifically configured to record a first power value of the cascaded filter when the incident optical signal is incident;
selecting a first intermediate variable from the intermediate variable combination as the target intermediate variable;
adjusting the first intermediate variable into a second intermediate variable according to the first preset step length, the first coordinate transformation matrix and a first adjustment mode, and recording a second power value of the cascade filter at the moment, wherein the first adjustment mode is used for indicating an increasing or decreasing symbol of the first intermediate variable;
determining a second adjustment mode of the second intermediate variable according to the first power value and the second power value, wherein the second adjustment mode is used for indicating an increasing or decreasing symbol of the second intermediate variable;
and adjusting the second intermediate variable into a third intermediate variable according to the first preset step length, the first coordinate transformation matrix and the second adjustment mode, and recording a third power value of the cascade filter at the moment.
14. The apparatus of claim 13, wherein the processing module is further configured to determine a second preset step size according to the first power value and the second power value;
and adjusting the second intermediate variable into a fourth intermediate variable according to the second preset step length, the first coordinate transformation matrix and the second adjustment mode, and recording a fourth power value of the cascade filter at the moment.
15. The apparatus according to claim 14, wherein the processing module is specifically configured to calculate a power change rate from the first power value and the second power value;
if the power change rate is larger than a preset threshold value, determining that the second preset step length is larger than the first preset step length;
and if the power change rate is smaller than the preset threshold, determining that the second preset step length is smaller than the first preset step length.
16. The apparatus of claim 13, wherein the processing module is further configured to determine a second coordinate transformation matrix according to the first power value and the second power value;
and adjusting the second intermediate variable into a fifth intermediate variable according to the first preset step length, the second coordinate transformation matrix and the second adjustment mode, and recording a fifth power value of the cascade filter at the moment.
17. The apparatus according to claim 16, wherein the processing module is specifically configured to calculate a power change rate according to the first power value and the second power value;
if the power change rate is larger than a preset threshold value, determining that the matrix condition number of the second coordinate transformation matrix is larger than the matrix condition number of the first coordinate transformation matrix;
and if the power change rate is smaller than the preset threshold value, determining that the matrix condition number of the second coordinate transformation matrix is smaller than the matrix condition number of the first coordinate transformation matrix.
18. The apparatus according to any one of claims 13 to 17, wherein the processing module is specifically configured to determine that the second adjustment manner of the second intermediate variable is opposite to the increase or decrease sign of the first adjustment manner if the second power value is smaller than the first power value;
and if the second power value is larger than the first power value, determining that the increasing and decreasing signs of the second adjusting mode of the second intermediate variable are the same as the increasing and decreasing signs of the first adjusting mode.
19. A wavelength locker comprising: a plurality of processors and a memory, wherein the memory has a computer readable program stored therein, and the processors are configured to execute the program in the memory for performing the method of any one of claims 1 to 9.
20. A computer-readable storage medium comprising instructions which, when executed on a computer, cause the computer to perform the method of claims 1 to 9.
21. A computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of claims 1 to 9.
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