An optical link testing method and device based on optical frequency domain reflection

Abstract

The application discloses an optical link test method and device based on optical frequency domain reflection, which comprises the following steps: measuring echo optical signals of an optical link in an initial state by using a frequency domain reflectometer to obtain a first signal; measuring the echo optical signals of the optical link after changing the function state of the optical link again by using the frequency domain reflectometer to obtain a second signal; performing fast Fourier transform on the measured first signal and second signal respectively to obtain corresponding frequency domain signals and a distance-power relationship curve; converting the same frequency band in the two frequency domain signals into time domain signals by sliding window interception; performing cross-correlation operation on the time domain signals of the two groups of signals to obtain Rayleigh scattering frequency shift; and obtaining a distance-power distribution curve by calculation in combination with a coefficient. The application can realize fast and accurate measurement and calibration of optical field amplitude and phase parameters of an integrated system from a device level to a link level, and efficiently measure return loss, insertion loss, spectrum, delay and other parameters of an optical link on a chip.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic information technology, and in particular to an optical link testing method and device based on optical frequency domain reflection. BACKGROUND

[0002] The on-chip optical link has the advantages of seamless connection with fiber communication and sensing network, high-precision wideband sensing and transmission capacity in large scale, and high-efficiency information processing capacity in small scale. The signal consistency across macro, meso and micro scales will avoid energy and information loss caused by frequent electro-optical conversion, and maximize the efficiency. As a prerequisite for the realization of large-scale application of on-chip optical link, the input and output power and noise parameters of the key nodes and in-line devices need to be accurately measured, which are important data for performance optimization of the optical link.

[0003] In the prior art, conventional on-chip optical link calibration methods include temperature compensation calibration, feedback-based adaptive calibration, electrical / optical signal calibration, static calibration of manufacturing deviation, and multi-point sampling and interpolation calibration. However, the above calibration methods have certain defects, for example:

[0004] The temperature compensation calibration method may not be fast enough in responding to sudden temperature changes due to the response speed of the temperature sensor, and the temperature compensation calibration may not be able to eliminate the effects caused by manufacturing process differences; the feedback-based adaptive calibration method relies on complex feedback circuits, which may increase the power consumption and design complexity of the chip, and at the same time, feedback calibration usually reacts slowly to sudden environmental changes; the electrical / optical signal calibration method requires additional conversion circuits, which increases the chip area, and at the same time, as the link rate increases, the noise in the electro-optical / optical-electrical conversion process is difficult to avoid; the static calibration method of manufacturing deviation is only effective in the initial state, and is difficult to adapt to subsequent environmental changes and device aging, and cannot provide long-term link stability; the multi-point sampling and interpolation calibration method is time-consuming in the sampling and interpolation process, which may cause the link calibration to be not real-time, and in addition, this method is invalid when the environmental change exceeds the sampling range. Based on the above-mentioned defects, the present application provides an optical link testing method and device based on optical frequency domain reflection to solve such problems. SUMMARY

[0005] Therefore, in order to solve the problems in the prior art, on the one hand, the present application provides an optical link testing method based on optical frequency domain reflection, which comprises: a frequency domain reflectometer measuring and demodulating a return light signal of a probe light signal of the frequency domain reflectometer in an initial state of an optical link, to obtain a first signal, the return light signal carrying optical field amplitude and phase information of a node to be measured in the link;

[0006] The optoelectronic regulation unit in the on-chip optical link is regulated to change the state of the optical link, the frequency domain reflectometer demodulates the echo optical signal of the probe optical signal of the frequency domain reflectometer in the optical link whose state has changed to obtain a second signal, and the echo optical signal carries the optical field amplitude and phase information of the same to-be-measured node after the link changes;

[0007] The first signal and the second signal are respectively subjected to fast Fourier transform to obtain a frequency domain signal of the first signal and a frequency domain signal of the second signal;

[0008] The signal segments of the frequency domain signal of the first signal and the signal segments of the frequency domain signal of the second signal are respectively subjected to inverse fast Fourier transform to be converted into a time domain signal of the first signal and a time domain signal of the second signal to obtain a distance and frequency shift relationship curve;

[0009] The time domain signal of the first signal and the time domain signal of the second signal are subjected to cross-correlation operation to obtain Rayleigh scattering frequency shifts of each to-be-measured node in the entire optical link.

[0010] The distance and power distribution curve is obtained by calculation in combination with the coefficient to obtain the amplitude and phase modulation result of the echo optical signal after passing through the optical link.

[0011] Further, before the step of obtaining the first signal by measuring the echo optical signal by using the frequency domain reflectometer, the method further comprises:

[0012] The output end of the frequency domain reflectometer is connected to the input end of the on-chip optical link through an optical fiber, and the input end of the frequency domain reflectometer is connected to the output end of the on-chip optical link to form a loop.

[0013] Further, before the step of respectively subjecting the frequency domain signal of the first signal and the frequency domain signal of the second signal to inverse fast Fourier transform, the method further comprises:

[0014] The frequency domain signal of the first signal and the frequency domain signal of the second signal of the same to-be-measured node are respectively intercepted by using a fixed moving window to obtain the signal segments of the frequency domain signal of the first signal and the signal segments of the frequency domain signal of the second signal.

[0015] Further, the optical link comprises a protection layer, a link test layer, an isolation layer and a functional layer, and the protection layer, the link test layer, the isolation layer and the functional layer are sequentially overlapped.

[0016] Further, the structure of the functional layer is a Mach-Zehnder structure or a microring structure.

[0017] Further, the laser linear frequency modulation bandwidth of the frequency domain reflectometer is 10-50 nm.

[0018] On the other hand, the application provides an optical link testing device based on optical frequency domain reflection, comprising:

[0019] frequency domain reflectometer;

[0020] at least one group of on-chip optical links, the output end of the frequency domain reflectometer and the input end of the on-chip optical link are connected by an optical fiber, and the input end of the frequency domain reflectometer and the output end of the on-chip optical link are connected by an optical fiber.

[0021] Further, the upper optical link comprises a protection layer, a link test layer, an isolation layer and a functional layer, and the protection layer, the link test layer, the isolation layer and the functional layer are sequentially overlapped.

[0022] Further, the structure of the functional layer is a Mach-Zehnder structure or a micro-ring structure.

[0023] Beneficial effects: by using the test method of the present application, the distance and frequency shift relationship curve and the distance and power distribution curve can be obtained, and through the analysis of the distance and frequency shift relationship curve and the distance and power distribution curve, the fast and accurate measurement and calibration of the optical field amplitude and phase parameters of the integrated system from the device level to the link level can be realized, the return loss, the insertion loss, the spectrum, the delay and other parameters of the on-chip optical link can be efficiently measured, and the defects existing in the prior art can be effectively solved. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0025] Figure 1 for the optical link test method based on optical frequency domain reflection of the present application;

[0026] Figure 2 for the optical link test method based on optical frequency domain reflection of the present application;

[0027] Figure 3 for the overall structure of the optical link test device based on optical frequency domain reflection of the present application;

[0028] Figure 4 for the overall structure of the optical link test device based on optical frequency domain reflection of the present application;

[0029] In the figure: 1, frequency domain reflectometer; 2, on-chip optical link; 21, protection layer; 22, link test layer; 23, isolation layer; 24, functional layer; 3, optical fiber.

[0030] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0032] It should be noted that all directionality indications (such as up, down, left, right, front, back, and the like) in the embodiments of the present application are only used to explain the relative relationships between the components, the motion conditions, and the like of the nodes to be measured, in a certain specific posture (as shown in the drawings). If the specific posture changes, the directionality indications also change accordingly.

[0033] In addition, the descriptions of “first”, “second”, and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as “first” and “second” can explicitly or implicitly include at least one of the features. In addition, “and / or” throughout the text includes three solutions, for example, A and / or B includes A technical solution, B technical solution, and A and B simultaneously meet the technical solution. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of a person of ordinary skill in the art. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0034] The present application is beneficial to the development of integration and miniaturization, and can be applied to communication, artificial intelligence, structural health monitoring and other fields, and solves the problems of online error correction and distributed measurement in optical links.

[0035] As shown in Figures 1-4 The embodiment of the present application provides an optical link test method based on optical frequency domain reflection, which comprises the following steps:

[0036] S1, connecting the output end of the frequency domain reflectometer with the input end of the on-chip optical link through an optical fiber, and connecting the input end of the frequency domain reflectometer with the output end of the on-chip optical link, to form a loop;

[0037] S2, the frequency domain reflectometer demodulates the echo optical signal of the probe optical signal of the frequency domain reflectometer in the optical link in the initial state to obtain a first signal, and the echo optical signal carries the optical field amplitude and phase information of the node to be measured in the link;

[0038] S3, regulating the optoelectronic regulation unit in the on-chip optical link to change the state of the optical link, and the frequency domain reflectometer demodulates the echo optical signal of the probe optical signal of the frequency domain reflectometer in the optical link whose state has changed to obtain a second signal, and the echo optical signal carries the optical field amplitude and phase information of the same to-be-measured node after the link changes;

[0039] S4, performing fast Fourier transform on the first signal and the second signal respectively to obtain a frequency domain signal of the first signal and a frequency domain signal of the second signal;

[0040] S5, intercepting the frequency domain signal of the first signal and the frequency domain signal of the second signal of the same to-be-measured node through a fixed moving window to obtain a signal segment of the frequency domain signal of the first signal and a signal segment of the frequency domain signal of the second signal;

[0041] S6, performing inverse fast Fourier transform on the signal segment of the frequency domain signal of the first signal and the signal segment of the frequency domain signal of the second signal respectively to convert them into a time domain signal of the first signal and a time domain signal of the second signal, and obtain a distance and frequency shift relationship curve of the frequency domain reflectometer to the to-be-measured node of the optical link;

[0042] S7, performing cross-correlation operation on the time domain signal of the first signal and the time domain signal of the second signal to obtain Rayleigh scattering frequency shift of each to-be-measured node of the entire optical link;

[0043] S8, combining the coefficient, calculating the distance and power distribution curve of the frequency domain reflectometer to the to-be-measured node of the optical link to obtain the phase amplitude modulation result of the echo optical signal passing through the optical link.

[0044] In the embodiment, the on-chip optical link is provided with a protective layer, a link test layer, an isolation layer and a functional layer, the measurement echo optical signal of the optical frequency reflectometer is connected with the functional layer through an optical fiber, the backscattering signal of the measurement light enters the test layer through evanescent wave coupling, and then is returned to the optical frequency reflectometer, and processes such as interference, photoelectric conversion, data sampling and analog-digital conversion are completed in the demodulation system of the optical frequency reflectometer, and finally the demodulation is completed through a signal processing algorithm to obtain the on-chip optical link test result.

[0045] The similarity between the two groups of time domain signals is calculated through cross-correlation operation to obtain Rayleigh scattering frequency shift, and the Rayleigh scattering frequency shift reflects the state change in the optical link, such as power change or link disturbance.

[0046] In the step, the distance and frequency shift relationship curve of the frequency domain reflectometer to the to-be-measured node of the optical link reflects the state change of the optical link at different positions, and the distance and power distribution curve of the frequency domain reflectometer to the to-be-measured node of the optical link reflects the power intensity of the echo signal at each point in the optical link.

[0047] A multi-layer structure is designed, and an evanescent wave coupling is performed using an on-chip waveguide structure to form a monitoring network. This enables amplitude and phase calibration from the device to the link, and can efficiently measure parameters such as return loss, insertion loss, spectrum, and delay of the link, thus realizing distributed measurement functions.

[0048] The formulas used to calculate the distance and power distribution curves include:

[0049] Formula 1: ;

[0050] Formula 2: ;

[0051] Substituting Formula 1 into Formula 2, we obtain Formula 3: ;

[0052] Spatial resolution calculation formula: ΔR = c / (2 × B), B = c / (2 × ΔR)

[0053] In the formula, R represents the distance from the frequency domain reflectometer to the optical link detecting the node under test, ΔR represents the spatial resolution, B represents the bandwidth of the laser linear frequency modulated signal in the frequency domain reflectometer, S represents the linear modulation frequency, T represents the signal duration, and f represents the intermediate frequency signal frequency. is a coefficient, and c represents the speed of light.

[0054] The cross-correlation calculation formula in step S7 is:

[0055] In the formula, A(λ): the first signal, with wavelength λ on the x-axis and amplitude on the y-axis; B(λ): the second signal, with wavelength λ on the x-axis and amplitude on the y-axis; Δλ: the wavelength shift (similar to time domain delay). Cross-correlation results under wavelength shift;

[0056] Using the test method of this application, distance-frequency shift curves and distance-power distribution curves can be obtained. By analyzing the results of the distance-frequency shift curves and distance-power distribution curves, rapid and accurate measurement and calibration of optical field amplitude and phase parameters of integrated systems from the device level to the link level can be achieved. The return loss, insertion loss, spectrum, delay and other parameters of on-chip optical links can be measured efficiently, which can effectively solve the defects of various test methods in the prior art.

[0057] In one embodiment, the on-chip optical link includes a protective layer 21, a link test layer 22, an isolation layer 23, and a functional layer 24, which are arranged in an overlapping manner.

[0058] In the embodiment, the functional layer 24 is in a Mach-Zehnder structure or a micro-ring structure, so that the waveguide layer is added without changing the original structure of the optical link device, the amplitude and phase information of the specified to-be-measured node can be quickly and efficiently obtained, and great advantages can be achieved in a large-scale optical link.

[0059] In one embodiment, the laser chirp bandwidth of the frequency domain reflectometer 1 is 10-50 nm.

[0060] In the embodiment, the frequency domain reflectometer 1 is composed of two directional couplers and a phase shifter, has a length of about 200 um and a width of 50 um, two monitoring points are arranged at the input and output of the structure, the spatial interval between the two points is about 100 um, so that the spatial resolution of the frequency domain reflectometer 1 needs to be less than 50 um to distinguish the echo optical signals of the two monitoring points, and according to the spatial resolution calculation formula, the laser chirp bandwidth of the frequency domain reflectometer 1 needs to reach 10-50 nm.

[0061] The embodiment of the application provides an optical link testing device based on optical frequency domain reflection, which comprises:

[0062] The frequency domain reflectometer 1;

[0063] The input end and the output end of the frequency domain reflectometer 1 are connected to the input end and the output end of the on-chip optical link 2 through the optical fiber 3.

[0064] In the embodiment, the on-chip optical link comprises a protection layer 21, a link testing layer 22, an isolation layer 23 and a functional layer 24, and the protection layer 21, the link testing layer 22, the isolation layer 23 and the functional layer 24 are arranged in sequence.

[0065] In the embodiment, the functional layer 24 is in a Mach-Zehnder structure or a micro-ring structure, so that the waveguide layer is added without changing the original structure of the optical link device, the amplitude and phase information of the specified to-be-measured node can be quickly and efficiently obtained, and great advantages can be achieved in a large-scale optical link;

[0066] The measurement echo optical signal of the optical frequency reflectometer is connected to the functional layer 24 through the optical fiber 3, the backscattering signal of the measurement light is coupled into the testing layer through evanescent waves and is returned to the optical frequency reflectometer, the processes of interference, photoelectric conversion, data sampling and analog-digital conversion are completed in the demodulation system of the optical frequency reflectometer, and finally the demodulation is completed through a signal processing algorithm.

[0067] In one embodiment, the laser chirp bandwidth of the frequency domain reflectometer 1 is 10-50 nm.

[0068] In the embodiment, the frequency domain reflectometer 1 is composed of two directional couplers and a phase shifter, with a length of about 200 um and a width of 50 um, two monitoring points are arranged at the input and output of the structure, and the spatial interval of the two points is about 100 um, which requires that the spatial resolution of the frequency domain reflectometer 1 is less than 50 um to distinguish the echo light signals of the two monitoring points, and according to the spatial resolution calculation formula, the laser linear frequency modulation bandwidth of the frequency domain reflectometer 1 needs to reach 10-50 nm.

[0069] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made under the inventive concept of the present application, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present application.

Claims

1. A method of optical link testing based on optical frequency domain reflectometry, characterized in that, The method comprises the following steps: A frequency domain reflectometer measures and demodulates a return light signal of a probe light signal of the frequency domain reflectometer in an initial state of an optical link, to obtain a first signal, the return light signal carrying amplitude and phase information of an optical field of a node to be measured in the link; An optoelectronic control unit in an on-chip optical link is controlled to change the state of the optical link, and a frequency domain reflectometer measures and demodulates a return light signal of a probe light signal of the frequency domain reflectometer in the optical link with the changed state, to obtain a second signal, the return light signal carrying amplitude and phase information of an optical field of the same node to be measured after the change of the link; The first signal and the second signal are respectively subjected to fast Fourier transform, to obtain a frequency domain signal of the first signal and a frequency domain signal of the second signal; The signal segments of the frequency domain signal of the first signal and the frequency domain signal of the second signal are respectively subjected to inverse fast Fourier transform, to be converted into a time domain signal of the first signal and a time domain signal of the second signal, to obtain a distance and frequency shift curve of the frequency domain reflectometer to the node to be measured in the optical link; The time domain signal of the first signal and the time domain signal of the second signal are subjected to cross-correlation operation, to obtain Rayleigh scattering frequency shift of each node to be measured in the optical link; In combination with a coefficient, a distance and power distribution curve of the frequency domain reflectometer to the node to be measured in the optical link is obtained by calculation, to obtain a phase and amplitude modulation result of the return light signal after passing through the optical link.

2. The optical link testing method based on optical frequency domain reflection according to claim 1, characterized in that, Before the step of measuring the return light signal by the frequency domain reflectometer to obtain the first signal, the method further comprises: An output end of the frequency domain reflectometer is connected to an input end of the on-chip optical link by an optical fiber, and an input end of the frequency domain reflectometer is connected to an output end of the on-chip optical link, to form a loop.

3. The optical link testing method based on optical frequency domain reflectometry according to claim 1, characterized in that, Before the step of respectively subjecting the frequency domain signal of the first signal and the frequency domain signal of the second signal to inverse fast Fourier transform, the method further comprises: The frequency domain signal of the first signal and the frequency domain signal of the second signal of the same node to be measured are respectively intercepted by a fixed moving window, to obtain signal segments of the frequency domain signal of the first signal and the frequency domain signal of the second signal.

4. The optical link testing method based on optical frequency domain reflectometry according to claim 2, characterized in that, The on-chip optical link comprises a protection layer, a link test layer, an isolation layer and a functional layer, and the protection layer, the link test layer, the isolation layer and the functional layer are sequentially overlapped.

5. The optical link testing method based on optical frequency domain reflectometry according to claim 4, characterized in that, The functional layer has a Mach-Zehnder structure or a microring structure.

6. The optical link testing method based on optical frequency domain reflectometry according to claim 1, wherein, The laser linear frequency modulation bandwidth of the frequency domain reflectometer is 10-50 nm.

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