Optical link test method and device based on optical frequency domain reflection

Abstract

The invention discloses an optical link test method and device based on optical frequency domain reflection, and the method comprises the steps: employing a frequency domain reflectometer to measure an echo optical signal in an initial state of an optical link, and obtaining a first signal; after the function state of the optical link is changed, the frequency domain reflectometer is utilized again to measure the optical link echo optical signal, and a second signal is obtained; respectively carrying out fast Fourier transform on the measured first signal and second signal to obtain corresponding frequency domain signals, and obtaining a distance and power relation curve; intercepting the same frequency band in the two frequency domain signals through a sliding window, converting the two frequency domain signals into time domain signals, and carrying out cross-correlation operation on the time domain signals of the two groups of signals to obtain Rayleigh scattering frequency shift; and combining the coefficients to obtain a distance and power distribution curve through calculation. According to the invention, rapid and accurate measurement and calibration of light field amplitude and phase parameters of an integrated system from a device level to a link level can be realized, and parameters of return loss, insertion loss, spectrum, delay and the like of an on-chip optical link can be efficiently measured.

Description

Technical Field

[0001] The present invention 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 Art

[0002] With its high efficiency, lightweight, and anti-interference characteristics, on-chip optical links can seamlessly connect with fiber-optic communications and sensor networks. They have high-precision broadband perception and transmission capabilities at large scales, and efficient information processing capabilities at small scales. This signal consistency across macro, meso, and micro scales will avoid energy and information loss caused by frequent electro-optical conversion in the link, and maximize efficiency. As a prerequisite for the large-scale application of on-chip optical links, parameters such as input and output power and noise of key nodes and devices along the line need to be accurately measured as important data for optimizing optical link performance.

[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 deviations, and multi-point sampling and interpolation calibration. However, all of the above calibration methods have certain defects, such as:

[0004] The temperature compensation calibration method may not be able to respond to sudden temperature changes in time because the response speed of the temperature sensor may not be fast enough, and the temperature compensation calibration may not be able to eliminate the impact 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. At the same time, feedback calibration usually responds slowly to sudden environmental changes; the electrical / optical signal calibration method requires additional conversion circuits, which will increase the chip area. At the same time, as the link rate increases, the noise impact in the electro-optical / photoelectric conversion process is difficult to avoid; the static calibration method of manufacturing deviation is only effective in the initial state, and it 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 in real time. In addition, the method fails when the environmental changes exceed the sampling range. Based on the above-mentioned defects, the present application proposes an optical link testing method and device based on optical frequency domain reflection to solve such problems. Summary of the invention

[0005] Based on this, in order to solve the problems existing in the prior art, on the one hand, the present application provides an optical link testing method based on optical frequency domain reflection, comprising a frequency domain reflectometer measuring and demodulating an echo optical signal of a detection optical signal of the frequency domain reflectometer in an optical link in an initial state to obtain a first signal, wherein the echo optical signal carries the optical field amplitude and phase information of the node to be tested in the link;

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

[0007] 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;

[0008] 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, converting them into the time domain signal of the first signal and the time domain signal of the second signal, and obtaining a distance and frequency shift relationship curve;

[0009] Performing a cross-correlation operation on the time domain signal of the first signal and the time domain signal of the second signal to obtain Rayleigh scatter frequency shift of each node to be tested in the entire optical link;

[0010] Combined with the coefficients, the distance and power distribution curves are calculated to obtain the phase-amplitude modulation result of the echo optical signal after passing through the optical link.

[0011] Furthermore, before the step of measuring the echo optical signal using a frequency domain reflectometer system to obtain the first signal, the method further includes:

[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] Furthermore, before the step of performing inverse fast Fourier transform on the frequency domain signal of the first signal and the frequency domain signal of the second signal respectively, the method further includes:

[0014] The frequency domain signal of the first signal and the frequency domain signal of the second signal of the same node to be tested are respectively intercepted 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.

[0015] Furthermore, the upper optical link includes 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 overlapped in sequence.

[0016] Furthermore, the structure of the functional layer is a Mach-Zehnder structure or a micro-ring structure.

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

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

[0019] Frequency domain reflectometry;

[0020] At least one set of on-chip optical links, the output end of the frequency domain reflectometer and the input end of the on-chip optical link, and the input end of the frequency domain reflectometer and the output end of the on-chip optical link are all connected through optical fibers.

[0021] Furthermore, the upper optical link includes 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 overlapped in sequence.

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

[0023] Beneficial effect: By adopting the test method of the present application, a distance and frequency shift relationship curve and a distance and power distribution curve can be obtained. By analyzing the results of the distance and frequency shift relationship curve and the distance and power distribution curve, 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 achieved, and the return loss, insertion loss, spectrum, delay and other parameters of the on-chip optical link can be efficiently measured, which can effectively solve the defects existing in various test methods in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0025] Figure 1 It is a schematic diagram of the steps of the optical link testing method based on optical frequency domain reflection of the present invention;

[0026] Figure 2 This is a signal processing flow chart of an optical link testing method based on optical frequency domain reflection according to the present invention;

[0027] Figure 3 It is a schematic diagram of the overall structure of an optical link testing device based on optical frequency domain reflection according to the present invention;

[0028] Figure 4 It is a schematic diagram of the on-chip optical link structure of the optical link testing device based on optical frequency domain reflection of the present invention;

[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 realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relationship between the components relative to the nodes to be measured, the movement status, etc. under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, "and / or" in the full text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] This application is conducive to the development of integration and miniaturization, and can be applied to multiple fields such as communications, artificial intelligence, structural health monitoring, etc., to solve the problems of online error correction and distributed measurement in optical links.

[0035] like Figure 1-4 As shown, the embodiment of the present application provides an optical link testing method based on optical frequency domain reflection, including:

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

[0037] S2, the frequency domain reflectometer measures and demodulates the echo optical signal of the detection optical signal of the frequency domain reflectometer in the optical link in the initial state to obtain a first signal, where 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 control unit in the on-chip optical link to change the state of the optical link, and the frequency domain reflectometer measures and demodulates the echo optical signal of the detection 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 node to be measured 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. intercept the frequency domain signal of the first signal and the frequency domain signal of the second signal of the same node to be tested respectively 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. Perform 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 the time domain signal of the first signal and the time domain signal of the second signal, and obtain a distance and frequency shift relationship curve from the frequency domain reflectometer to the optical link detection node to be tested;

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

[0043] S8. Combining the coefficients, the distance and power distribution curve from the frequency domain reflectometer to the optical link detection node to be tested are obtained by calculation, and the phase amplitude modulation result of the echo optical signal after passing through the optical link is obtained.

[0044] In this embodiment, the on-chip optical link is provided with a protection layer, a link test layer, an isolation layer and a functional layer. The measurement echo optical signal of the optical frequency reflectometer is connected to the functional layer through an optical fiber. The backscattered signal of the measurement light enters the test layer through evanescent wave coupling and then is transmitted back to the optical frequency reflectometer. Interference, photoelectric conversion, data sampling and analog-to-digital conversion are completed in the demodulation system of the optical frequency reflectometer. The demodulation is finally completed through a signal processing algorithm to obtain the on-chip optical link test result.

[0045] By performing cross-correlation operations on two sets of time domain signals and calculating the similarity between the signals, the Rayleigh scattered frequency shift is obtained. The Rayleigh scattered frequency shift reflects the state changes in the optical link, such as power changes or link disturbances.

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

[0047] Design a multi-layer structure and use the on-chip waveguide structure to couple evanescent waves to form a monitoring network, realize the amplitude and phase calibration from the device to the link, and efficiently measure the return loss, insertion loss, spectrum, delay and other parameters of the link to realize distributed measurement function;

[0048] The formulas for calculating the distance and power distribution curves include:

[0049] Formula 1: B = S × T;

[0050] Formula 2:

[0051] Substituting formula 1 into formula 2, we get formula 3:

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

[0053] Where R represents the distance from the frequency domain reflectometer to the optical link detection node to be tested, ΔR represents the spatial resolution, B represents the bandwidth of the laser linear frequency modulation signal in the frequency domain reflectometer, S represents the linear modulation frequency, T represents the time width of the signal, and f represents the intermediate frequency signal frequency. is the coefficient and c represents the speed of light.

[0054] The cross-correlation calculation formula in step S7 is: AB (Δλ)=∫A(λ)·B(λ+Δλ)dλ

[0055] Where A(λ): first signal, with wavelength λ on the horizontal axis and amplitude on the vertical axis; B(λ): second signal, with wavelength λ on the horizontal axis and amplitude on the vertical axis; Δλ: wavelength shift (similar to delay in the time domain); C AB (Δλ): cross-correlation result under wavelength shift;

[0056] By adopting the test method of the present application, a distance and frequency shift relationship curve and a distance and power distribution curve can be obtained. By analyzing the results of the distance and frequency shift relationship curve and the distance and power distribution curve, 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 achieved, and the return loss, insertion loss, spectrum, delay and other parameters of the on-chip optical link can be efficiently measured, which can effectively solve the defects existing in various test methods in the prior art.

[0057] In one embodiment, the on-chip optical link includes a protection layer 21, a link test layer 22, an isolation layer 23 and a functional layer 24, and the protection layer 21, the link test layer 22, the isolation layer 23 and the functional layer 24 are overlapped in sequence.

[0058] In this embodiment, the structure of the functional layer 24 is a Mach-Zehnder structure or a micro-ring structure. By setting it in this way, the waveguide layer is added without changing the original structure of the optical link device, and the amplitude and phase information of the specified node to be measured can be quickly and efficiently obtained, which can play a huge advantage in large-scale optical links.

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

[0060] In this embodiment, the frequency domain reflectometer 1 system is composed of two directional couplers and a phase shifter, with a length of about 200um and a width of 50um. Two monitoring points are set at the input and output of the structure, and the spatial interval between the two points is about 100um. This requires that the spatial resolution of the frequency domain reflectometer 1 system is less than 50um to distinguish the echo light signals of the two monitoring points. According to the spatial resolution calculation formula, it can be obtained that the laser linear frequency modulation bandwidth of the frequency domain reflectometer 1 system needs to reach 10-50nm.

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

[0062] Frequency domain reflectometer 1;

[0063] At least one set of on-chip optical links 2 , the input end and the output end of the frequency domain reflectometer 1 are correspondingly connected to the input end and the output end of the on-chip optical link 2 through the optical fiber 3 .

[0064] In this embodiment, the on-chip optical link includes a protection layer 21, a link test layer 22, an isolation layer 23 and a functional layer 24, and the protection layer 21, the link test layer 22, the isolation layer 23 and the functional layer 24 are overlapped in sequence.

[0065] In this embodiment, the structure of the functional layer 24 is a Mach-Zehnder structure or a micro-ring structure. By adding a waveguide layer without changing the original structure of the optical link device, the amplitude and phase information of the specified node to be measured can be quickly and efficiently obtained, which can play a huge advantage in large-scale optical links.

[0066] The measurement echo optical signal of the optical frequency reflectometer is connected to the functional layer 24 through the optical fiber 3, and the backscattered signal of the measurement light enters the test layer through evanescent wave coupling and is transmitted back to the optical frequency reflectometer. The interference, photoelectric conversion, data sampling and analog-to-digital conversion processes are completed in the demodulation system of the optical frequency reflectometer, and the demodulation is finally completed through the signal processing algorithm.

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

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

[0069] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An optical link testing method based on optical frequency domain reflection, characterized in that: include: The frequency domain reflectometer measures and demodulates the echo optical signal of the detection optical signal of the frequency domain reflectometer in the optical link in the initial state to obtain a first signal, wherein the echo optical signal carries the optical field amplitude and phase information of the node to be measured in the link; The optoelectronic control unit in the on-chip optical link is regulated to change the state of the optical link, and the frequency domain reflectometer measures and demodulates the echo optical signal of the detection optical signal of the frequency domain reflectometer in the optical link whose state has changed to obtain a second signal, wherein the echo optical signal carries the optical field amplitude and phase information of the same node to be measured after the link changes; 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; Performing inverse fast Fourier transform on 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 respectively, converting them into the time domain signal of the first signal and the time domain signal of the second signal, and obtaining a distance and frequency shift relationship curve from the frequency domain reflectometer to the optical link detection node to be tested; Performing a cross-correlation operation on the time domain signal of the first signal and the time domain signal of the second signal to obtain Rayleigh scatter frequency shift of each node to be tested in the entire optical link; Combined with the coefficients, the distance and power distribution curve from the frequency domain reflectometer to the node to be tested in the optical link detection are obtained by calculation, and the phase-amplitude modulation result of the echo optical signal after passing through the optical link is obtained.

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 echo optical signal by using a frequency domain reflectometer system to obtain the first signal, the method further includes: 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.

3. The optical link testing method based on optical frequency domain reflection according to claim 1, characterized in that: Before the step of performing inverse fast Fourier transform on the frequency domain signal of the first signal and the frequency domain signal of the second signal respectively, the method further includes: The frequency domain signal of the first signal and the frequency domain signal of the second signal of the same node to be tested are respectively intercepted 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.

4. The optical link testing method based on optical frequency domain reflection 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, wherein 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 reflection according to claim 4, characterized in that: The structure of the functional layer is a Mach-Zehnder structure or a micro-ring structure.

6. The optical link testing method based on optical frequency domain reflection according to claim 1, characterized in that: The laser linear frequency modulation bandwidth of the frequency domain reflectometer system is 10-50nm.

7. An optical link test device based on optical frequency domain reflection, characterized in that: include: Frequency domain reflectometry; 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, and the input end of the frequency domain reflectometer and the output end of the on-chip optical link are all connected through optical fibers.

8. The optical link test device based on optical frequency domain reflection according to claim 7, characterized in that: The on-chip optical link comprises a protection layer, a link test layer, an isolation layer and a functional layer, wherein the protection layer, the link test layer, the isolation layer and the functional layer are sequentially overlapped.

9. The optical link test device based on optical frequency domain reflection according to claim 8, characterized in that: The structure of the functional layer is a Mach-Zehnder structure or a micro-ring structure.

10. The optical link test device based on optical frequency domain reflection according to claim 7, characterized in that: The laser linear frequency modulation bandwidth of the frequency domain reflectometer system is 10-50nm.

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