A method and system for extracting the coupling strength of a microring based on optical heterodyne detection

Abstract

This invention discloses a method and system for extracting the coupling strength of a micro-ring based on optical heterodyne detection. Using optical heterodyne detection technology, a linearly modulated laser signal is split into two paths: one path serves as the local oscillator reference light; the other path, as the signal light, enters the micro-ring, generating a back-reflected signal light. The back-reflected signal light and the local oscillator reference light undergo optical heterodyne beat frequency interference to generate an original beat frequency signal. The resonant and non-resonant light in the original beat frequency signal are distinguished, and then subjected to FFT transformation to the range domain. In the range domain, the initial signal intensity of the resonant light within the ring waveguide and the signal intensity of the non-resonant light coupled to the straight waveguide are extracted. The difference between the two is used to obtain the micro-ring coupling strength. This method combines range-domain distributed detection and frequency-domain spectral response measurement capabilities, locating the micro-ring position and comparing the light intensity changes along the coupling path to extract the micro-ring coupling strength. Compared to traditional transmission spectrum testing methods, this method improves measurement accuracy, reliability, and repeatability.

Description

Technical Field

[0001] This invention relates to the field of receiving technology, and specifically to a method and system for extracting the coupling strength of a microring based on optical heterodyne detection. Background Technology

[0002] Currently, the coupling strength of microring resonators (microrings) is measured using traditional transmission spectrum testing methods. However, due to polarization state fluctuations causing test instability and the occurrence of mode splitting during the test, coupled with interference from other devices on the chip, problems such as insufficient extraction efficiency of microring coupling strength and susceptibility to external interference can arise. Summary of the Invention

[0003] To address the existing technical problems, improve the efficiency of microring coupling strength extraction, and suppress external interference, this application provides a method and system for microring coupling strength extraction based on optical heterodyne detection.

[0004] Firstly, a method for extracting the coupling strength of microrings based on optical heterodyne detection is provided, adopting the following technical solution:

[0005] Obtaining the original beat frequency signal: The linear frequency modulated laser signal is divided into two paths: one path is used as the local oscillator reference light, and the other path is used as the signal light; the signal light enters the micro-ring and generates a back-reflected signal light that returns along the original path; the back-reflected signal light and the local oscillator reference light undergo optical heterodyne beat frequency interference in the optical coupling device to generate the original beat frequency signal containing resonant light and non-resonant light;

[0006] Distinguish between resonant and non-resonant light in the original beat frequency signal;

[0007] Extract the initial signal intensity of the resonant light within the ring waveguide;

[0008] Extracting the signal intensity of non-resonant light within a coupled straight waveguide;

[0009] Extracting coupling strength: The initial signal intensity of the resonant light in the ring waveguide is subtracted from the signal intensity of the non-resonant light in the coupled straight waveguide to obtain the micro-ring coupling strength.

[0010] Furthermore, when distinguishing between resonant and non-resonant light in the original beat frequency signal, the specific steps are as follows:

[0011] Resonant light and non-resonant light are distinguished based on the beat frequency amplitude: an amplitude threshold is set, which is higher than the maximum value of the beat frequency amplitude in the non-resonant state; if the beat frequency amplitude in the original beat frequency signal exceeds the amplitude threshold, it is determined to be resonant light; if the beat frequency amplitude in the original beat frequency signal does not exceed the amplitude threshold, it is determined to be non-resonant light.

[0012] Furthermore, the initial signal intensity of the resonant light within the ring waveguide is extracted as follows:

[0013] The original beat frequency signal of the distinguished resonant light is converted to the distance domain by fast Fourier transform to obtain the distance domain propagation curve of the resonant light in the ring waveguide; the light intensity value corresponding to the starting point where the light intensity drops from the maximum value to a preset proportion in the distance domain propagation curve of the resonant light in the ring waveguide is the initial signal intensity of the resonant light in the ring waveguide.

[0014] Furthermore, the preset ratio is 10%.

[0015] Furthermore, the signal intensity of the non-resonant light within the coupled straight waveguide is extracted as follows:

[0016] The distinguished non-resonant light is transformed to the range domain using a fast Fourier transform to obtain the range domain propagation curve of the non-resonant light in the coupled straight waveguide; then the coupling region of the micro-ring is calibrated; and the average value of the reflection intensity within the coupling region is obtained.

[0017] Secondly, a microring coupling strength extraction system based on optical heterodyne detection is provided, including a control module, a swept laser, a beam splitter, a circulator, a microring resonator, an optical coupling device, and a signal processing module;

[0018] The control module controls the output of the frequency-sweeping laser to produce linearly frequency-modulated laser light.

[0019] The frequency-sweeping laser outputs linearly frequency-modulated laser light according to the requirements of the control module;

[0020] The beam splitter splits the optical signal output from the swept laser into two paths: one path serves as the local oscillator reference light and directly enters the optical coupler; the other path serves as the signal light and enters the micro-ring resonator under test via the circulator.

[0021] The microring resonator includes a straight waveguide, a ring waveguide, and a coupling region between the straight waveguide and the ring waveguide;

[0022] The circulator is used to separate the signal light from the back-reflected signal light, enabling single-end extraction of the back-reflected light signal.

[0023] The optical coupling device combines the local oscillator reference light and the back-reflected light to generate the original beat frequency signal carrying the optical path difference information of the two arms, and sends the original beat frequency signal to the signal processing module.

[0024] The signal processing module performs data processing on the original beat frequency signal: distinguishing between resonant and non-resonant light in the original beat frequency signal; performing fast Fourier transform on the resonant and non-resonant light respectively to obtain the range domain signal; extracting the initial signal intensity of the resonant light in the ring waveguide; extracting the signal intensity of the non-resonant light in the coupled straight waveguide; and subtracting the initial signal intensity of the resonant light in the ring waveguide from the signal intensity of the non-resonant light in the coupled straight waveguide to obtain the micro-ring coupling strength.

[0025] Thirdly, a computer-readable storage medium is provided, on which a computer program is stored, wherein when the computer program is executed by a processor, the steps of the microring coupling strength extraction method based on optical heterodyne detection as described in the first aspect are implemented.

[0026] The beneficial effects of this invention are as follows:

[0027] This application employs optical heterodyne detection technology, combining range-domain distributed detection and frequency-domain spectral response measurement capabilities to precisely locate the micro-ring position. By comparing changes in light intensity along the coupling path, the coupling strength of the micro-ring is extracted. Compared to traditional transmission spectrum testing methods, this invention avoids testing instability caused by polarization state fluctuations, and effectively circumvents mode splitting phenomena and interference from other on-chip devices during the testing process, significantly improving measurement reliability and repeatability.

[0028] After heterodyne detection and deskewing, the output signal bandwidth is reduced, which lowers the requirements for the sampling rate and memory capacity of the analog-to-digital converter.

[0029] Pulse compression requires only one Fast Fourier Transform (FFT), and the number of FFT points is reduced, which decreases the computational load of digital signal processing and makes engineering implementation simpler. Attached Figure Description

[0030] Figure 1 This is a structural diagram of the micro-ring coupling strength extraction system according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram illustrating the extraction principle of micro-ring coupling strength according to an embodiment of the present invention;

[0032] Figure 3 This is a flowchart of the method for extracting the coupling strength of micro-rings according to an embodiment of the present invention;

[0033] Figure 4 This is the appearance of the tested microring in an embodiment of the present invention;

[0034] Figure 5 This is a waveform diagram of the original beat frequency signal in an embodiment of the present invention;

[0035] Figure 6 This is a waveform diagram of the resonant light in the original beat frequency signal of an embodiment of the present invention;

[0036] Figure 7 This is a waveform diagram of the non-resonant light in the original beat frequency signal of an embodiment of the present invention;

[0037] Figure 8 This is a graph showing the propagation curve of non-resonant light in the original beat frequency signal of micro-ring sample A in an embodiment of the present invention.

[0038] Figure 9This is a graph showing the propagation curve of non-resonant light in the original beat frequency signal of micro-ring sample B in an embodiment of the present invention.

[0039] Figure 10 This is a graph showing the propagation curve of non-resonant light in the original beat frequency signal of micro-ring sample C in an embodiment of the present invention.

[0040] Figure 11 This is a graph showing the propagation curve of non-resonant light in the original beat frequency signal of micro-ring sample D in an embodiment of the present invention.

[0041] Figure 12 This is a graph showing the propagation curves of resonant light in the original beat frequency signals of micro-ring samples A, B, C, and D in an embodiment of the present invention. Detailed Implementation

[0042] The present invention will now be described in further detail.

[0043] One embodiment of the present invention is a microring coupling strength extraction system based on optical heterodyne detection, such as... Figure 1 As shown, it includes a control module, a swept laser, a beam splitter, a circulator, a micro-ring resonator, an optical coupling device, and a signal processing module.

[0044] The control module controls the output frequency of the frequency-scanning laser.

[0045] A swept-frequency laser is a light source based on a micro-ring coupling intensity extraction system using optical heterodyne detection. It has a constant sweep speed and outputs a linearly frequency-modulated coherent laser signal.

[0046] The beam splitter splits the optical signal output from the swept laser into two paths: one path serves as the local oscillator reference light, which directly enters the optical coupler; the other path serves as the signal light, which enters the micro-ring under test via the circulator.

[0047] A microring resonator (microring) is a device under test (DUT) comprising a straight waveguide, a ring waveguide, and a coupling region between the two. Signal light is transmitted through the straight waveguide. When a specific wavelength of light in the signal light satisfies the microring resonance condition, it is coupled into the ring waveguide through the coupling region and resonates within the ring waveguide, resulting in enhanced resonance. During the cyclic propagation of the resonant light within the ring waveguide, due to surface defects, roughness, or structural inhomogeneities on the sidewalls of the ring waveguide, some light undergoes backscattering, generating back-reflected light that propagates in the opposite direction of the original transmission. This back-reflected light returns along the original path: passing sequentially through the coupling region and the straight waveguide, and finally exiting from the input end of the straight waveguide, where it is extracted by the circulator and guided to the optical coupling device.

[0048] The circulator is used to separate the signal light from the back-reflected signal light, enabling single-end extraction of the back-reflected light signal.

[0049] An optical coupling device combines the local oscillator reference light and the back-reflected light to generate a beat frequency interference signal (i.e., the original beat frequency signal) carrying information about the optical path difference between the two arms. This original beat frequency signal is then sent to the signal processing module. Since the local oscillator reference light and the back-reflected light are two frequency-modulated continuous waves with the same modulation slope, they generate a beat frequency signal with a fixed frequency after mixing. After low-pass filtering, a single-frequency sine wave signal can be obtained (by deskewing, the linear frequency-modulated signal is converted into a single-frequency signal, thereby reducing the sampling rate requirement and extracting distance information). The frequency of this signal is proportional to the time delay between the two signals.

[0050] The signal processing module performs data processing on the beat frequency interference signal. For example... Figure 2 As shown, the signal processing module distinguishes between the resonant and non-resonant wavelengths in the original beat frequency signal based on amplitude characteristics. Fast Fourier Transform is performed on both the resonant and non-resonant wavelengths to obtain the range-domain signals. The spectral characteristics of the resonant wavelength in the range domain are analyzed to extract the initial signal intensity within the ring waveguide. The spectral characteristics of the non-resonant wavelength in the range domain are also analyzed to extract the signal intensity of the coupled straight waveguide (the section of the straight waveguide adjacent to the ring waveguide in the micro-ring, which enables optical coupling input / output). The difference between the initial signal intensity within the ring waveguide and the signal intensity of the coupled straight waveguide is calculated to obtain the micro-ring coupling strength.

[0051] The working principle of the micro-ring coupling strength extraction system is as follows: The control module controls the swept-frequency laser to output a linearly frequency-modulated coherent laser signal. This signal is split into two paths by a beam splitter: one path serves as the local oscillator reference light, directly entering the optical coupler; the other path serves as the signal light, entering the micro-ring under test via a circulator, coupling into the ring waveguide, and generating a back-reflected signal light returning along the original path (the back-reflected signal light is the light returning to the input port along the original path in the micro-ring, including resonant and non-resonant light). The back-reflected light returns to the circulator via the original path and then enters the optical coupler. In the optical coupler, the back-reflected light undergoes heterodyne beat frequency interference with the local oscillator reference light, generating a raw beat frequency signal which is sent to the signal processing and acquisition module. The signal processing module acquires and processes the raw beat frequency signal to extract the micro-ring coupling strength.

[0052] Another embodiment of the present invention is a method for extracting the coupling strength of microrings based on optical heterodyne detection, such as... Figure 3 As shown, it includes the following steps:

[0053] Step 1: Obtain the raw beat frequency signal.

[0054] The control module controls the swept-frequency laser to output a linearly frequency-modulated coherent laser signal. This signal is split into two paths by a beam splitter: one path serves as the local oscillator reference light, directly entering the optical coupler; the other path serves as the signal light, entering the input port of the micro-ring via a circulator, coupling into the micro-ring waveguide, and generating back-reflected light (which includes resonant and non-resonant light). In this embodiment, the micro-ring under test is as follows: Figure 4 As shown, the red arrow indicates light passing through a straight waveguide to the output port, and the blue arrow indicates back-reflected light returning to the input port via the original path. After reaching the circulator from the input port, the back-reflected light enters the optical coupler. In the optical coupler, the back-reflected light interferes with the local oscillator reference light, forming a raw beat frequency signal containing both resonant and non-resonant light, such as... Figure 5 As shown.

[0055] Step 2: Distinguish between resonant and non-resonant light in the original beat frequency signal.

[0056] Since optical heterodyne detection is a distributed detection technique, there is spatial overlap between the non-resonant light and the resonant light signal just coupled into the micro-ring in the range domain image. Therefore, it is necessary to separate and measure the non-resonant light to achieve accurate resolution of the coupling strength.

[0057] The original beat frequency signal exhibits periodic resonance characteristics, and the beat frequency amplitude of the resonant light is significantly enhanced. For example... Figure 5 In the signal, non-resonant light appears as a continuously distributed background signal, while resonant light appears as a localized peak. Based on the beat frequency amplitude, resonant and non-resonant light are distinguished as follows: An amplitude threshold is set (e.g., 0.1 mV; 0.1 mV is only an example value, and in actual applications, this threshold needs to be dynamically adjusted according to parameters such as laser output power and echo intensity). This threshold is higher than the maximum value of the beat frequency amplitude in the non-resonant state. If the beat frequency amplitude in the original beat frequency signal exceeds this amplitude threshold, it is determined to be resonant light; if the beat frequency amplitude in the original beat frequency signal does not exceed this amplitude threshold, it is determined to be non-resonant light. In this embodiment, the waveform in the resonant region is as follows: Figure 6 As shown, the waveform in the non-resonant region is as follows: Figure 7 As shown.

[0058] There is no fixed execution order for the extraction of non-resonant optical signal intensity in coupled straight waveguides and the extraction of initial signal intensity of resonant optical signal in ring waveguides. In this specification, steps three and four are used only for ease of description and should not be construed as limiting the execution order.

[0059] Step 3: Extract the initial signal intensity of the resonant light within the ring waveguide.

[0060] Since the sweeping speed of the frequency-sweeping laser is constant, the frequency of the original beat frequency signal is proportional to the distance from the reflection point, and the amplitude of the original beat frequency signal is proportional to the reflection intensity. The original beat frequency signal of the resonant light separated in step two (such as...) Figure 6 The time-domain signal shown (horizontal axis represents detection time, i.e., laser wavelength at different times) is converted to a frequency-domain signal (horizontal axis represents beat frequency, corresponding to the distance to the reflection point) through a Fast Fourier Transform (FFT). Then, based on the linear relationship between beat frequency and distance, the frequency-domain signal is transformed to the distance domain, and the propagation characteristics of the resonant light are extracted to obtain the distance-domain propagation curve of the resonant light in the ring waveguide. Light at the resonant frequency is effectively coupled into the ring waveguide of the micro-ring and propagates multiple times within the ring waveguide. Its reflected signal appears as a series of distributed signals in the distance-domain image, eventually attenuating to the system's noise floor. The light intensity value corresponding to the starting point where the light intensity drops from its maximum value by more than a preset proportion (e.g., 10%) in the distance-domain propagation curve of the resonant light in the ring waveguide is the initial signal intensity of the resonant light in the ring waveguide.

[0061] In this embodiment, microring samples with coupling lengths of 200 μm, 400 μm, 600 μm, and 800 μm were prepared, and named A, B, C, and D, respectively. The propagation curves of the resonant light in the original beat frequency signals of microring samples A, B, C, and D are shown below. Figure 12 As shown, the signal intensities within the ring waveguides of the four micro-ring samples A, B, C, and D are -121.9±0.1 dB, -116.3±0.1 dB, -113.1±0.1 dB, and -110.6±0.1 dB, respectively. It can be seen that as the coupling length increases, the initial light intensity coupled into the ring waveguide increases, indicating an increase in coupling strength. Sample A, with the lowest coupling strength, has the lowest resonant optical loss amplitude because it emits the least amount of light each time; while sample D, with the highest coupling strength, has the highest resonant optical loss amplitude.

[0062] Step 4: Extract the intensity of the non-resonant optical signal within the coupled straight waveguide.

[0063] 4-1) The non-resonant light separated in step two (such as...) Figure 7 The time-domain beat frequency signal shown is represented by the horizontal axis, which is the detection time (i.e., the laser wavelength at different times). It is then converted to a frequency-domain signal using FFT (the horizontal axis represents the beat frequency, corresponding to the distance to the reflection point). Based on the linear relationship between the beat frequency and the distance, the frequency-domain signal is transformed to the distance domain. The non-resonant light propagation characteristics are extracted to obtain the distance-domain propagation curve of the non-resonant light in the coupled straight waveguide (referring to the straight waveguide section adjacent to the ring waveguide in the micro-ring, which realizes optical coupling input / output).

[0064] 4-2) Calibrate the coupling region of the microring, as follows:

[0065] like Figures 8-11As shown, the propagation curve of non-resonant light within a coupled straight waveguide exhibits a strong reflection peak at both the beginning and end of the curve, with the reflection intensity exceeding that of the middle straight waveguide by more than 25 dB. These two strong reflection peaks are caused by... Figure 4 The reflected light is formed at the locations of the input and output ports shown. First, based on the actual distance measurement of the test sample, the specific position of the micro-ring coupling point relative to the input or output port can be determined. Then, in Figures 8-11 The location marked on the curve is the coupling region of the micro-ring.

[0066] In this embodiment, microring samples with coupling lengths of 200 μm, 400 μm, 600 μm and 800 μm were prepared and named A, B, C and D, respectively. Figures 8-11 In the diagram, boxes indicate the coupling regions between the straight waveguides and the loop waveguides of samples A, B, C, and D.

[0067] 4-3) Obtain the intensity of the non-resonant optical signal in the coupled straight waveguide.

[0068] The signal intensity within the coupled straight waveguide is the same as the non-resonant optical signal intensity, reflecting the optical power level of the straight waveguide. After calibrating the coupling region of the microring, the arithmetic mean of the reflection intensity within the coupling region is calculated.

[0069] In this embodiment, the non-resonant optical signal intensities in the straight waveguides of micro-ring samples A, B, C, and D are -97.1±0.2dB, -97.0±0.8dB, -97.4±0.7dB, and -97.3±0.5dB, respectively.

[0070] Step 5: Extract coupling strength

[0071] The method for calculating coupling strength is as follows:

[0072] The difference between the initial signal intensity of the resonant light in the ring waveguide and the signal intensity of the non-resonant light in the coupled straight waveguide is the coupling strength of the micro-ring.

[0073] The results of this embodiment are shown in Table 1.

[0074] Table 1. Coupling strength extraction results of four samples in this embodiment of the invention.

[0075]

[0076] The results show that the coupling strength increases monotonically with the increase of coupling length, which verifies the effectiveness and repeatability of the proposed method.

[0077] This application employs optical heterodyne detection technology to split a linearly frequency-modulated laser signal into two paths: one path serves as the local oscillator reference light; the other path, as the signal light, enters the micro-ring, generating a back-reflected signal light. The back-reflected signal light and the local oscillator reference light undergo optical heterodyne beat frequency interference to generate the original beat frequency signal. The resonant and non-resonant light in the original beat frequency signal are distinguished, and then subjected to FFT transformation to the range domain. In the range domain, the initial signal intensity of the resonant light within the ring waveguide and the signal intensity of the non-resonant light coupled to the straight waveguide are extracted. The difference between the two is used to obtain the micro-ring coupling strength. This method combines range-domain distributed detection and frequency-domain spectral response measurement capabilities, enabling precise location of the micro-ring and extraction of its coupling strength by comparing changes in light intensity along the coupling path. Compared with traditional transmission spectrum testing methods, this invention avoids the instability caused by polarization state fluctuations, and can effectively avoid mode splitting and interference from other on-chip devices during the testing process, significantly improving measurement reliability and repeatability.

[0078] This application also has the following advantages:

[0079] After heterodyne detection deskewing (referring to the process of mixing two frequency-modulated continuous wave signals (local oscillator reference light and back-reflected light) with the same frequency modulation slope and then obtaining a single-frequency sine wave signal (original beat frequency signal) through low-pass filtering), the output signal bandwidth is significantly reduced, thereby reducing the requirements for the sampling rate and memory capacity of the analog-to-digital converter.

[0080] Pulse compression requires only one FFT and reduces the number of FFT points, significantly reducing the computational load of digital signal processing and making engineering implementation simpler.

[0081] Heterodyne detection de-chirping converts the delay information of the target echo into frequency information, effectively compressing the echo signal bandwidth and reducing signal processing complexity. However, it also imposes certain limitations on the target detection range. The bandwidth after compression depends on the radial size of the target; the larger the target, the wider the bandwidth. Optical microring structures can efficiently constrain the light field in both time and space. Their extremely small size confines the light field within a micrometer-scale volume, significantly enhancing the interaction intensity between light and matter. Because the microring resonates only at specific frequencies, it possesses excellent frequency selectivity and spectral modulation capabilities, contributing to the research and development and manufacturing of high-performance optical frequency modulation devices.

[0082] In some embodiments, certain aspects of the above-described techniques may be implemented by one or more processors of a processing system executing software. The software includes one or more sets of executable instructions stored or otherwise tangibly implemented on a non-transitory computer-readable storage medium. The software may include instructions and certain data that, when executed by one or more processors, manipulate one or more processors to perform one or more aspects of the above-described techniques. The non-transitory computer-readable storage medium may include, for example, magnetic or optical disk storage devices, solid-state storage devices such as flash memory, cache, random access memory (RAM), or other non-volatile memory devices. The executable instructions stored on the non-transitory computer-readable storage medium may be source code, assembly language code, object code, or other instruction formats interpreted or otherwise executed by one or more processors.

[0083] Computer-readable storage media can include any storage medium or combination of storage media that can be accessed by a computer system during use to provide instructions and / or data to the computer system. Such storage media can include, but are not limited to, optical media (e.g., optical discs (CDs), digital versatile optical discs (DVDs), Blu-ray discs), magnetic media (e.g., floppy disks, magnetic tapes, or magnetic hard disks), volatile memory (e.g., random access memory (RAM) or cache), non-volatile memory (e.g., read-only memory (ROM) or flash memory), or microelectromechanical systems (MEMS) based storage media. Computer-readable storage media can be embedded in a computing system (e.g., system RAM or ROM), fixedly attached to a computing system (e.g., a magnetic hard disk drive), removably attached to a computing system (e.g., an optical disc or universal serial bus-based (USB) flash memory), or coupled to a computer system via a wired or wireless network (e.g., network-accessible storage (NAS)).

[0084] While the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the invention. Any equivalent changes or modifications made without departing from the spirit and scope of the invention are also within the scope of protection of the invention. Therefore, the scope of protection of the present invention should be determined by the claims of this application.

Claims

1. A method for extracting the coupling strength of microrings based on optical heterodyne detection, characterized in that, Includes the following steps: Obtaining the original beat frequency signal: The linear frequency modulated laser signal is divided into two paths: one path is used as the local oscillator reference light, and the other path is used as the signal light; the signal light enters the micro-ring and generates a back-reflected signal light that returns along the original path; the back-reflected signal light and the local oscillator reference light undergo optical heterodyne beat frequency interference in the optical coupling device to generate the original beat frequency signal containing resonant light and non-resonant light; Distinguish between resonant and non-resonant light in the original beat frequency signal; Extract the initial signal intensity of the resonant light within the ring waveguide; Extracting the signal intensity of non-resonant light within a coupled straight waveguide; Extracting coupling strength: The initial signal intensity of the resonant light in the ring waveguide is subtracted from the signal intensity of the non-resonant light in the coupled straight waveguide to obtain the micro-ring coupling strength.

2. The method for extracting micro-ring coupling strength based on optical heterodyne detection according to claim 1, characterized in that, When distinguishing between resonant and non-resonant light in the original beat frequency signal, the specific steps are as follows: Resonant light and non-resonant light are distinguished based on the beat frequency amplitude: an amplitude threshold is set, which is higher than the maximum value of the beat frequency amplitude in the non-resonant state; if the beat frequency amplitude in the original beat frequency signal exceeds the amplitude threshold, it is determined to be resonant light; if the beat frequency amplitude in the original beat frequency signal does not exceed the amplitude threshold, it is determined to be non-resonant light.

3. The method for extracting micro-ring coupling strength based on optical heterodyne detection according to claim 2, characterized in that, The initial signal intensity of the resonant light within the ring waveguide is extracted as follows: The original beat frequency signal of the distinguished resonant light is converted to the distance domain by fast Fourier transform to obtain the distance domain propagation curve of the resonant light in the ring waveguide; the light intensity value corresponding to the starting point where the light intensity drops from the maximum value to a preset proportion in the distance domain propagation curve of the resonant light in the ring waveguide is the initial signal intensity of the resonant light in the ring waveguide.

4. The method for extracting micro-ring coupling strength based on optical heterodyne detection according to claim 3, characterized in that, The preset ratio is 10%.

5. The method for extracting micro-ring coupling strength based on optical heterodyne detection according to claim 2, characterized in that, When extracting the signal intensity of non-resonant light within a coupled straight waveguide, the specific steps are as follows: The distinguished non-resonant light is transformed to the range domain using a fast Fourier transform to obtain the range domain propagation curve of the non-resonant light in the coupled straight waveguide; then the coupling region of the micro-ring is calibrated. Obtain the average value of the reflection intensity within the coupling region.

6. A microring coupling strength extraction system based on optical heterodyne detection, used to implement the microring coupling strength extraction method based on optical heterodyne detection as described in claim 1, characterized in that, It includes a control module, a swept laser, a beam splitter, a circulator, a micro-ring resonator, an optical coupling device, and a signal processing module; The control module controls the output of the frequency-sweeping laser to produce linearly frequency-modulated laser light. The frequency-sweeping laser outputs linearly frequency-modulated laser light according to the requirements of the control module; The beam splitter splits the optical signal output from the swept laser into two paths: one path serves as the local oscillator reference light and directly enters the optical coupler; the other path serves as the signal light and enters the micro-ring resonator under test via the circulator. The microring resonator includes a straight waveguide, a ring waveguide, and a coupling region between the straight waveguide and the ring waveguide; The circulator is used to separate the signal light from the back-reflected signal light, enabling single-end extraction of the back-reflected light signal; The optical coupling device combines the local oscillator reference light and the back-reflected light to generate the original beat frequency signal carrying the optical path difference information of the two arms, and sends the original beat frequency signal to the signal processing module. The signal processing module performs data processing on the original beat frequency signal: distinguishing between resonant and non-resonant light in the original beat frequency signal; performing fast Fourier transform on the resonant and non-resonant light respectively to obtain the range domain signal; extracting the initial signal intensity of the resonant light in the ring waveguide; extracting the signal intensity of the non-resonant light in the coupled straight waveguide; and subtracting the initial signal intensity of the resonant light in the ring waveguide from the signal intensity of the non-resonant light in the coupled straight waveguide to obtain the micro-ring coupling strength.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the microring coupling strength extraction method based on optical heterodyne detection as described in any one of claims 1-5.

Images