Rapid demodulation system and method for on-chip large-scale microcavity array

Abstract

The invention relates to a fast demodulation system and method for an on-chip large-scale microcavity array. The system comprises a sweep frequency laser; the first optical fiber coupler is used for dividing the light source into a first light source and a second light source; the micro-cavity array transmission signal arm is used for receiving a first light source of the sweep frequency laser, the first light source enters the on-chip large-array micro-cavity sensing device after being subjected to polarization processing, and the first light source is converted into an electric signal after receiving disturbance of an external sensing signal; the auxiliary interference reference arm is used for receiving a second light source of the frequency sweeping laser, processing the second light source to obtain two beams of coherent light with opposite phases, and then converting the coherent light into electric signals; the same-frequency trigger arm is used for transmitting a same-frequency trigger signal sent by the sweep-frequency laser; and the signal processing device is used for collecting and processing signals. The method effectively inhibits frequency axis distortion and spectral line broadening caused by frequency sweeping nonlinearity of the laser, and can be suitable for accurate demodulation of a large-scale and high-Q-value microcavity sensing array.

Description

Technical Field

[0001] The present application relates to the field of integrated photonics technology, and more specifically, to a fast demodulation system and method for on-chip large-scale microcavity arrays. Background Art

[0002] In recent years, with the rapid development of on-chip optical processes, light source technology, and optical information processing, emerging optical sensors have attracted widespread attention and application due to their high sensitivity and resistance to electromagnetic interference. In particular, sensors based on on-chip optical microcavities concentrate light field energy in a very small area. Through high-Q optical resonance, they achieve ultra-high measurement accuracy and unprecedented sensitivity, making them potential unit devices for large-scale parallel sensing.

[0003] The current sensing architecture of integrated optical microcavity sensor arrays can be divided into mechanical, spectroscopic and wavelength division multiplexing types. Among them, the integrated optical sensing architecture based on on-chip wavelength division multiplexing can realize multi-channel parallel sensing. By calibrating the corresponding sensing unit signal by wavelength, it not only ensures the quality of the sensing signal, but also eliminates the need for multiple reading devices. This solution has advantages in terms of the number of channels, reading signal quality, and packaging difficulty. There are two commonly used demodulation schemes. One is to use a narrow linewidth tunable laser in conjunction with a photodetector to achieve high-precision sensing, but the ordinary tunable laser has a limited sweep speed and can only demodulate slow-changing applications. The application scenarios are limited. At the same time, the integration of tunable lasers with high tuning range and high output power is difficult, and the realization of miniaturized systems still faces many difficulties. Another solution is to use a broadband light source with a large spectral range in conjunction with a spectrometer. In comparison, broadband light sources are easier to process, but high-throughput and high-precision sensor arrays require a large-bandwidth, high-resolution spectrometer to analyze the output spectrum of the sensor array. This places higher demands on the performance of the spectrometer, and the scanning speed of the spectrometer is limited, so it can only be used for slow-changing applications.

[0004] Effective parallel demodulation methods for large microcavity arrays, particularly for rapidly changing sensing applications, are currently lacking. In recent years, researchers have proposed methods such as optical frequency combs for parallel demodulation of microcavity arrays, but their limited bandwidth limits the number of possible demodulations and complicates the system. Therefore, research on fast demodulation and identification systems for large microcavity arrays remains a niche area. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology in performing fast parallel demodulation for large-scale on-chip optical microcavity arrays, such as a small number of demodulations and a complex system, and to provide a fast demodulation system and method for on-chip large-scale microcavity arrays, which can realize fast parallel demodulation of large-scale microcavity sensor arrays while also reducing the complexity of the system.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A fast demodulation system for large-scale on-chip microcavity arrays is provided, comprising: swept laser; A first optical fiber coupler is used to receive the light source of the frequency-sweeping laser and divide the light source into a first light source and a second light source; Microcavity array transmission signal arm: used to receive the first light source of the swept laser, polarize the first light source before entering the on-chip large array microcavity sensor device, receive the external sensor signal disturbance, convert it into an electrical signal, and obtain the microcavity array transmission spectrum signal; Auxiliary interferometer reference arm: used to receive the second light source of the swept laser, and process the second light source to obtain two coherent light beams with opposite phases, and then convert the coherent light into an electrical signal to obtain an auxiliary interferometer reference signal; Co-frequency trigger arm: used to transmit the co-frequency trigger signal emitted by the sweep laser; Signal processing device: used to collect the microcavity array transmission spectrum signal, auxiliary interference reference signal and co-frequency trigger signal, and obtain the demodulated sensor signal after signal processing.

[0007] The present invention provides a fast demodulation system for on-chip large-scale microcavity arrays. It utilizes a fast sweeping laser with a large bandwidth and high sweeping rate in conjunction with a photodetector to collect the entire spectrum of the microcavity array for demodulation of the sensor signal. At the same time, it uses an auxiliary interference reference arm to compensate for the error caused by the sweeping nonlinearity of the sweeping laser, effectively suppressing the frequency axis distortion and spectral line broadening caused by the laser sweeping nonlinearity. It can be applied to the precise demodulation of large-scale, high-Q value microcavity sensor arrays, solving the pain points of traditional microring sensor arrays such as the small number of demodulations and the complex demodulation methods, realizing fast parallel demodulation of large-scale microcavity sensor arrays and reducing system complexity.

[0008] In the present invention, a rapidly swept laser is employed as the core device of the overall demodulation system. Its sweep bandwidth determines the number of microcavities that can be covered, and the sweep rate determines the sensing applications that can be demodulated. When this system is used to implement parallel demodulation of on-chip microcavity array devices, the sensing signal is included in the demodulated transmission spectrum signal. For example, by tracking the drift of the microcavity resonance peak in each frame of the transmission spectrum signal, the external sensing signal causing the change can be calibrated. For example, the continuous sweep range of the rapidly swept laser reaches 500 GHz, which can cover more than 100 microrings. When the sweep rate reaches hundreds of hertz or kilohertz, the rapidly swept laser can demodulate and implement low-frequency vibration or stress sensing, such as pulse sensing. When the sweep rate reaches megahertz, it can demodulate and implement high-frequency applications such as ultrasound sensing and photoacoustic imaging.

[0009] Furthermore, the microcavity array transmission signal arm includes a first polarization controller, an on-chip large array microcavity sensor device, and a first photodetector, which are sequentially connected. The input end of the first polarization controller is connected to the first output end of the first fiber coupler; the output end of the first photodetector is connected to a signal processing device. A swept-frequency light source, or the first light source, entering the cavity array transmission signal arm first passes through the first polarization controller and, after polarization processing, enters the on-chip large array microcavity sensor device. At this point, after receiving disturbances from external sensor signals, it enters the first photodetector and is converted into an electrical signal—an auxiliary interference reference signal. Finally, it enters the signal processing device, which performs data acquisition and processing on this auxiliary interference reference signal.

[0010] Furthermore, the auxiliary interference reference arm includes a second fiber coupler, a fiber delay line, a second polarization controller, a third fiber coupler and a second photodetector; the input end of the second fiber coupler is connected to the second output end of the first fiber coupler, the first output end of the second fiber coupler is connected to the first input end of the third fiber coupler, the second output end of the second fiber coupler is connected to the input end of the second polarization controller after passing through the fiber delay line, the output end of the second polarization controller is connected to the second input end of the third fiber coupler, the output end of the third fiber coupler is connected to the input end of the second photodetector, and the output end of the second photodetector is connected to the signal processing device. The swept-frequency light source, i.e., the second light source, entering the auxiliary interference reference arm first enters the second fiber coupler. The second fiber coupler splits the second light source into two beams, one above the other, which enter the upper and lower arms respectively. The light source of the upper arm directly enters the third fiber coupler, and the light source of the lower arm passes through the fiber delay line and the second polarization controller in sequence before also entering the third fiber coupler. In the third fiber coupler, the light from the upper and lower arms interferes, resulting in two coherent lights with opposite phases. The coherent lights enter the second photodetector and are converted into electrical signals - auxiliary interference reference signals. Similarly, the auxiliary interference reference signals enter the signal processing device for data acquisition and processing.

[0011] Furthermore, the fiber delay line length typically needs to be greater than the length of the device under test, as the auxiliary interferometric reference signal must cover the full frequency range of the device under test. In the present invention, the on-chip large-array microcavity sensor device is typically shorter, and a 10m fiber delay line can be used. In practical applications, other lengths are also possible.

[0012] Furthermore, the microcavity array transmission signal arm also includes an adjustable optical attenuator, and the first output end of the first fiber coupler is connected to the first polarization controller after passing through the adjustable optical attenuator. The adjustable optical attenuator is located before the on-chip first polarization controller. The first light source first enters the adjustable optical attenuator and then enters the on-chip large array microcavity sensor device after passing through the first polarization controller. It is used to adjust the optical power entering the on-chip large array microcavity sensor device to avoid excessive light intensity entering the on-chip large array microcavity sensor device, which may cause device detuning. In actual applications, the adjustable optical attenuator can also be omitted depending on the different output optical powers of the aforementioned fast frequency sweeping laser and the different splitting ratios of the first fiber coupler.

[0013] Furthermore, the first fiber coupler divides the light source into a first light source and a second light source according to a splitting ratio of N1:N2, and the value of N1 is greater than the value of N2. The splitting ratio of the first fiber coupler is 9:1, in which 90% of the light, that is, most of the light enters the microcavity array transmission signal arm, taking into account the large device loss that may be introduced by the subsequent on-chip large array microcavity sensor device. And 10% of the light passes through the second fiber coupler and enters the auxiliary interference reference arm. The loss of this part is very small, and the required light intensity is also small. In actual application, according to the different losses of the microcavity array transmission signal arm and the auxiliary interference reference arm, fiber couplers with other splitting ratios can also be selected, such as 8:2, 99:1, etc.

[0014] Furthermore, the second optical fiber coupler splits the second light source into a third light source and a fourth light source at a splitting ratio of 1:1.

[0015] Furthermore, the microcavity structure of the on-chip large-array microcavity sensor device includes a microring resonant cavity, a Fabry-Perot resonant cavity, or a photonic crystal resonant cavity, and is fabricated using a chalcogenide material. The microcavity structure of the on-chip large-array microcavity sensor device can be a microring resonant cavity, a Fabry-Perot resonant cavity, a photonic crystal microcavity, or the like. In the present invention, a chalcogenide material is used to fabricate an array microcavity device comprising 100 microring resonant cavities. The fabrication process for the large-array microcavity sensor device on a large chip includes: depositing a high-quality chalcogenide thin film on a silicon dioxide substrate by vacuum thermal evaporation, spin-coating an electron beam exposure resin, and etching the microcavity array structure using electron beam lithography. After development, the microcavity array structure is then subjected to reactive ion beam etching.

[0016] Furthermore, the first photodetector is an avalanche photodetector; the second photodetector is a balanced photodetector. The avalanche photodetector utilizes the avalanche multiplication effect to perform secondary amplification of photogenerated carriers inside the device, and has a high gain. Since the microcavity array has large device losses, which will cause the optical power to drop significantly, the avalanche photodetector is suitable for detecting weak optical signals after passing through the microcavity array. In actual use, when there is no avalanche photodetector, ordinary photodetectors such as PIN diodes can also be used for detection, but it is necessary to introduce additional amplifiers at the front end to further amplify the optical signal, such as erbium-doped fiber amplifiers, and may introduce additional spontaneous radiation noise.

[0017] Furthermore, the frequency-sweeping laser, the first fiber coupler, the second fiber coupler, the fiber delay line, the second polarization controller, the third fiber coupler, the second photodetector, the first photodetector, the on-chip large-array microcavity sensor device, and the first photodetector are all connected through optical fibers; the frequency-sweeping laser, the first photodetector, and the second photodetector are all connected to the signal processing device through cables; and the on-chip large-array microcavity sensor device is connected to the optical fiber through fiber end face coupling or grating vertical coupling.

[0018] The present invention also provides a fast demodulation method for an on-chip large-scale microcavity array, which uses the fast demodulation system for an on-chip large-scale microcavity array described above, comprising the following steps: S1. At the signal processing device, the microcavity array transmission spectrum signal, the auxiliary interferometer reference signal, and the co-frequency trigger signal are obtained respectively; S2. Signal alignment is performed through cross-correlation, subtracting the time delay difference between the microcavity array transmission spectrum signal, the auxiliary interferometer reference signal, and the co-frequency trigger signal, and performing filtering and denoising. S3. Based on the rising edge of the sweep laser's co-frequency trigger signal, the microcavity array transmission spectrum signal and the auxiliary interferometer reference signal are synchronously sliced ​​into multiple sweep cycle segments. Each frame is a complete sweep cycle. S4. Extract the reference phase of the auxiliary interferometer reference signal within each sweep cycle through Hilbert transform to characterize the nonlinearity of the sweep process. Calculate the instantaneous phase from the reference phase, and remove phase jumps through unwrapping. S5. Calculate the instantaneous frequency based on the time derivative of the reference phase and compare it with the expected frequency of an ideal linear frequency sweep to obtain the frequency deviation. S6. Based on the nonlinear characteristics of the instantaneous frequency, the microcavity array transmission spectrum signal is non-uniformly resampled and remapped onto a uniform frequency axis to obtain a compensated and corrected microcavity array transmission spectrum signal. S7. Identify the position and morphology of the microcavity array resonance peaks for each frame of the compensated and corrected microcavity array transmission spectrum signal; S8. Track the position or shape change of each microcavity resonance peak in each frame, and demodulate and read the external sensor signal.

[0019] The present invention provides a fast demodulation method for on-chip large-scale microcavity arrays, which uses a fast frequency sweeping laser combined with a high-speed photodetector to achieve parallel demodulation of microcavity array sensing. This solves the pain points of traditional microring sensor arrays, such as a small number of demodulations and complex demodulation methods. The fast frequency sweeping feature also overcomes the problem of being limited by slow-changing applications, further broadening the application scenarios of on-chip microcavity array sensing.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a fast demodulation system and method for on-chip large-scale microcavity arrays. The system utilizes a fast sweeping laser with a large bandwidth and high sweeping rate in conjunction with a photodetector to collect the entire spectrum of the microcavity array for demodulation of the sensor signal. At the same time, an auxiliary interference reference arm is used to compensate for the error caused by the sweeping nonlinearity of the sweeping laser, effectively suppressing the frequency axis distortion and spectral line broadening caused by the laser sweeping nonlinearity. The system is suitable for the precise demodulation of large-scale, high-Q-value microcavity sensor arrays, solving the pain points of the traditional microring sensor array, such as the small number of demodulations and the complex demodulation methods, and realizing fast parallel demodulation of large-scale microcavity sensor arrays, thereby reducing the system complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FIG1 is a schematic structural diagram of a fast demodulation system for an on-chip large-scale microcavity array in one embodiment; Figure 2 Schematic diagram of a 10*10 micro-ring cavity array in one embodiment; Figure 3 Schematic diagram of the transmission spectrum of 100 micro-ring cavity arrays in one embodiment; Figure 4 FIG. 4 is a flow chart of a method for rapid demodulation to an on-chip large-scale microcavity array in another embodiment.

[0022] In the accompanying drawings: 100, microcavity array transmission signal arm; 200, auxiliary interference reference arm; 300, co-frequency trigger arm; 1, swept frequency laser; 2, first fiber coupler; 3, adjustable optical attenuator; 4, first polarization controller; 5, on-chip large array microcavity sensor device; 6, first photodetector; 7, second fiber coupler; 8, fiber delay line; 9, second polarization controller; 10, third fiber coupler; 11, second photodetector; 12, signal processing device; 101, microcavity array transmission spectrum signal; 201, auxiliary interference reference signal; 301, co-frequency trigger signal. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only and are schematic, not actual, representations. They should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced in size, and do not represent the actual dimensions of the products. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the drawings.

[0024] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "up", "down", "left", "right", etc. indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0025] Example 1 This embodiment is the first embodiment of a fast demodulation system for large-scale microcavity arrays on a chip. Figure 1 As shown, including: Swept laser 1; The first fiber coupler 2 is used to receive the light source of the frequency-sweeping laser 1 and divide the light source into a first light source and a second light source; The microcavity array transmission signal arm 100 is used to receive the first light source of the swept laser 1, perform polarization processing on the first light source before entering the on-chip large array microcavity sensor device 5, receive the disturbance of the external sensor signal, and convert it into an electrical signal to obtain the microcavity array transmission spectrum signal 101; Auxiliary interference reference arm 200: used to receive the second light source of the swept laser 1, and obtain two coherent light beams with opposite phases after processing the second light source, and then convert the coherent light into an electrical signal to obtain an auxiliary interference reference signal 201; The same-frequency trigger arm 300 is used to transmit the same-frequency trigger signal 301 emitted by the frequency-sweeping laser 1; The signal processing device 12 is used to collect the microcavity array transmission spectrum signal 101, the auxiliary interference reference signal 201 and the same-frequency trigger signal 301, and obtain the demodulated sensing signal after signal processing.

[0026] The present invention provides a fast demodulation system for on-chip large-scale microcavity arrays. It utilizes a fast sweeping laser 1 with a large bandwidth and a high sweeping rate in conjunction with a photodetector to collect the entire spectrum of the microcavity array for demodulation of the sensor signal. At the same time, it uses an auxiliary interference reference arm 200 to compensate for the error caused by the sweeping nonlinearity of the sweeping laser 1, effectively suppressing the frequency axis distortion and spectral line broadening caused by the laser sweeping nonlinearity. It can be applied to the precise demodulation of large-scale, high-Q value microcavity sensor arrays, solving the pain points of the traditional microring sensor array, such as the small number of demodulations and the complex demodulation methods, realizing fast parallel demodulation of large-scale microcavity sensor arrays, and reducing the system complexity.

[0027] Example 2 This embodiment is a second embodiment of a fast demodulation system for a large-scale microcavity array on a chip. This embodiment is similar to the first embodiment, except that: Figure 1 As shown, in this embodiment, the microcavity array transmission signal arm 100 includes a first polarization controller 4, an on-chip large array microcavity sensor device 5, and a first photodetector 6, which are connected in sequence. The input end of the first polarization controller 4 is connected to the first output end of the first fiber coupler 2; and the output end of the first photodetector 6 is connected to the signal processing device 12. The swept frequency light source, i.e., the first light source, entering the cavity array transmission signal arm first passes through the first polarization controller 4 and, after polarization processing, enters the on-chip large array microcavity sensor device 5. At this time, after receiving the disturbance of the external sensor signal, it enters the first photodetector 6 and is converted into an electrical signal - the auxiliary interference reference signal 201. Finally, it enters the signal processing device 12, which performs data acquisition and processing on the auxiliary interference reference signal 201.

[0028] The auxiliary interference reference arm 200 includes a second fiber coupler 7, a fiber delay line 8, a second polarization controller 9, a third fiber coupler 10 and a second photodetector 11; the input end of the second fiber coupler 7 is connected to the second output end of the first fiber coupler 2, the first output end of the second fiber coupler 7 is connected to the first input end of the third fiber coupler 10, the second output end of the second fiber coupler 7 is connected to the input end of the second polarization controller 9 after passing through the fiber delay line 8, the output end of the second polarization controller 9 is connected to the second input end of the third fiber coupler 10, the output end of the third fiber coupler 10 is connected to the input end of the second photodetector 11, and the output end of the second photodetector 11 is connected to the signal processing device 12. The swept frequency light source, i.e., the second light source, entering the auxiliary interference reference arm 200 first enters the second fiber coupler 7. The second fiber coupler 7 splits the second light source into two upper and lower light sources, which enter the upper and lower arms respectively. Among them, the light source of the upper arm directly enters the third fiber coupler 10, and the light source of the lower arm passes through the fiber delay line 8 and the second polarization controller 9 in sequence, and then enters the third fiber coupler 10. In the third fiber coupler 10, after the light of the upper and lower arms interferes, two coherent lights with opposite phases are obtained. The coherent lights enter the second photodetector 11 and are converted into electrical signals - auxiliary interference reference signals 201. Similarly, the auxiliary interference reference signals 201 enter the signal processing device 12 for data acquisition and processing.

[0029] In the present invention, a rapidly swept laser 1 is employed as the core device of the overall demodulation system. Its sweep bandwidth determines the number of microcavities that can be covered, and the sweep rate determines the sensing applications that can be demodulated. When this system is used to implement parallel demodulation of on-chip microcavity array devices, the sensing signal is included in the demodulated transmission spectrum signal. For example, by tracking the drift of the microcavity resonance peak in each frame of the transmission spectrum signal, the external sensing signal causing the change can be calibrated. For example, the continuous sweep range of the rapidly swept laser 1 reaches 500 GHz, which can cover more than 100 microrings. When the sweep rate of the rapidly swept laser 1 reaches hundreds of hertz or kilohertz, it can demodulate low-frequency vibration or stress sensing, such as pulse sensing. When the sweep rate reaches megahertz, it can demodulate high-frequency applications such as ultrasound sensing and photoacoustic imaging.

[0030] In this embodiment, the length of the optical fiber delay line 8 is typically greater than the length of the device under test, as the auxiliary interferometric reference signal 201 must cover the entire frequency range of the device under test. In the present invention, the on-chip large-array microcavity sensor device 5 is typically shorter, and a 10m optical fiber delay line 8 can be used. In actual applications, other lengths may also be used.

[0031] In this embodiment, the first fiber coupler 2 divides the light source into a first light source and a second light source according to a splitting ratio of N1:N2, and the value of N1 is greater than the value of N2. The splitting ratio of the first fiber coupler 2 is 9:1, in which 90% of the light, that is, the vast majority of the light, enters the microcavity array transmission signal arm 100. This is to take into account the large device losses that may be introduced by the subsequent large array microcavity sensor device 5 on the chip. 10% of the light passes through the second fiber coupler 7 and enters the auxiliary interference reference arm 200. The loss of this part is very small, and the required light intensity is also relatively low. In actual application, according to the different losses of the microcavity array transmission signal arm 100 and the auxiliary interference reference arm 200, fiber couplers with other splitting ratios can also be selected, such as 8:2, 99:1, etc.

[0032] In this embodiment, the second optical fiber coupler 7 splits the second light source into a third light source and a fourth light source at a splitting ratio of 1:1.

[0033] In this embodiment, the microcavity structure of the large array microcavity sensor device 5 on a chip includes a microring resonant cavity, a Fabry-Perot resonant cavity or a photonic crystal resonant cavity; and is made of chalcogenide materials. The microcavity structure of the large array microcavity sensor device 5 on a chip can be a microring resonant cavity, a Fabry-Perot resonant cavity, a photonic crystal microcavity, etc. In the present invention, a chalcogenide material is used to prepare an array microcavity device containing 100 microring resonant cavities, and its structure and transmission spectrum are as follows: Figure 2 and Figure 3 The fabrication process of the large-array microcavity sensor device 5 on a large wafer includes: depositing a high-quality chalcogenide thin film on a silicon dioxide substrate by vacuum thermal evaporation, spin-coating an electron beam exposure resin, and etching the microcavity array structure using electron beam lithography. After development, the microcavity array structure is then subjected to reactive ion beam etching.

[0034] In this embodiment, the first photodetector 6 is an avalanche photodetector; the second photodetector 11 is a balanced photodetector. The avalanche photodetector utilizes the avalanche multiplication effect to perform secondary amplification of photogenerated carriers inside the device, and has a high gain. Since the microcavity array has large device losses, which will cause the optical power to drop significantly, the avalanche photodetector is suitable for detecting weak optical signals after passing through the microcavity array. In actual use, when an avalanche photodetector is not available, ordinary photodetectors such as PIN diodes can also be used for detection, but it is necessary to introduce an additional amplifier at the front end to further amplify the optical signal, such as an erbium-doped fiber amplifier, and may introduce additional spontaneous emission noise.

[0035] In this embodiment, the swept-frequency laser 1, the first fiber coupler 2, the second fiber coupler 7, the fiber delay line 8, the second polarization controller 9, the third fiber coupler 10, the second photodetector 11, the first photodetector 6, the on-chip large array microcavity sensor device 5 and the first photodetector 6 are all connected through optical fibers; the swept-frequency laser 1, the first photodetector 6 and the second photodetector 11 are all connected to the signal processing device 12 through cables; the on-chip large array microcavity sensor device 5 is connected to the optical fiber through fiber end face coupling or grating vertical coupling.

[0036] The working principle of a fast demodulation system for a large-scale on-chip microcavity array in this embodiment is as follows: A swept laser 1 emits swept light, which passes through the first fiber coupler 2 and is split into two components: 10% of the second light source and 90% of the first light source. 10% of the light enters the second fiber coupler 7, serving as the light source for the auxiliary interferometer reference arm 200. The remaining 90% of the light enters the first polarization coupler, serving as the light source for the microcavity array transmission signal arm 100. After entering the second fiber coupler 7, the 10% light is further split into a 50% / 50% component, entering the upper and lower arms. The light from the upper arm directly enters the third fiber coupler 10, while the light from the lower arm passes through the fiber delay line 8 and the second polarization controller 9 before also entering the third fiber coupler 10. In the third fiber coupler 10, the light from the upper and lower arms interferes, generating two coherent beams with opposite phases. These coherent beams enter the second photodetector 11, where they are converted into electrical signals for data acquisition and processing by the signal processing device 12. The swept-frequency light entering the first polarization coupler passes through the second polarization controller 9 before entering the on-chip large-array microcavity sensor device 5. After receiving the external sensor signal disturbance, it enters the first photodetector 6 and is converted into an electrical signal. It then enters the signal processing device 12 for data acquisition and processing. Simultaneously, the swept-frequency laser 1 continuously transmits a synchronous trigger signal for the swept frequency to the signal processing device 12 via the co-frequency trigger arm 300.

[0037] Example 3 This embodiment is the third embodiment of a fast demodulation system for a large-scale on-chip microcavity array. This embodiment is similar to the second embodiment, except that the microcavity array transmission signal arm 100 further includes an adjustable optical attenuator 3. The first output end of the first fiber coupler 2 is connected to the first polarization controller 4 after passing through the adjustable optical attenuator 3. The adjustable optical attenuator 3 is located before the on-chip first polarization controller 4. The first light source first enters the adjustable optical attenuator 3 and then enters the large-scale on-chip microcavity array sensor device 5 after passing through the first polarization controller 4. The adjustable optical attenuator 3 is used to adjust the optical power entering the large-scale on-chip microcavity array sensor device 5 to prevent excessive light intensity from entering the large-scale on-chip microcavity array sensor device 5 and causing device detuning. In actual applications, depending on the output optical power of the aforementioned fast-sweep laser 1 and the splitting ratio of the first fiber coupler 2, the adjustable optical attenuator 3 can be omitted.

[0038] Example 4 This embodiment is an embodiment of a fast demodulation method for a large-scale microcavity array on a chip. This embodiment adopts any one of the fast demodulation systems for a large-scale microcavity array on a chip described in any one of the above embodiments 1 to 3. Figure 4 As shown, the following steps are included: S1. In the signal processing device 12, respectively, obtains the microcavity array transmission spectrum signal 101, the auxiliary interference reference signal 201, and the same frequency trigger signal 301; S2 is performed by cross-correlation operation to align the signals, subtract the delay difference of the microcavity array transmission spectrum signal 101, the auxiliary interference reference signal 201, and the same frequency trigger signal 301, and perform filtering and denoising; S3. According to the rising edge of the sweep laser 1 with the same frequency trigger signal 301, the microcavity array transmission spectrum signal 101 and the auxiliary interference reference signal 201 are sliced ​​synchronously and divided into multiple sweep cycle segments. After cutting each frame, a complete sweep cycle is formed. S4. Extracting the reference phase of the auxiliary interference reference signal 201 within each sweep cycle by Hilbert transform to characterize the nonlinearity of the sweep process; calculating the instantaneous phase by the reference phase and removing the phase jump by unwrapping operation; S5. Calculate the instantaneous frequency based on the time derivative of the reference phase and compare it with the expected frequency of an ideal linear frequency sweep to obtain the frequency deviation. S6. Based on the nonlinear characteristics of the instantaneous frequency, the microcavity array transmission spectrum signal 101 is non-uniformly resampled and the signal is remapped to a uniform frequency axis to obtain the compensated and corrected microcavity array transmission spectrum signal 101; S7. After compensation and correction, each frame of the microcavity array transmission spectrum signal 101 is subjected to position identification and morphological resolution of the microcavity array resonance peak; S8. Track the position or shape change of each microcavity resonance peak in each frame, and demodulate and read the external sensor signal.

[0039] The present invention provides a fast demodulation method for on-chip large-scale microcavity arrays, which uses a fast frequency sweeping laser 1 combined with a high-speed photodetector to achieve parallel demodulation of microcavity array sensing, solving the pain points of traditional microring sensor arrays, such as a small number of demodulations and complex demodulation methods. The fast frequency sweeping feature also overcomes the problem of being limited by slow-changing applications, further broadening the application scenarios of on-chip microcavity array sensing.

[0040] The existing frequency sweeping laser 1 has difficulty maintaining completely linear frequency sweeping when the frequency sweeping rate is fast. In the transmission spectrum of the microcavity sensor, the position of the resonance peak is the core parameter of the sensor. If the frequency sweeping rate of the laser is uneven, the frequency intervals corresponding to the data points collected at equal time intervals will be inconsistent. In the transmission spectrum finally generated, the scale of the frequency axis will be nonlinearly distorted, causing the actual position of the resonance peak to deviate from the measured position, and even causing the spectral line shape to be distorted and the resolution to be reduced. The present invention proposes a fast demodulation system and method for on-chip large-scale microcavity arrays. The system and method use auxiliary interferometer arms to compensate for the errors caused by the frequency sweeping nonlinearity of the frequency sweeping laser 1, effectively suppressing the frequency axis distortion and spectral line broadening caused by the laser frequency sweeping nonlinearity. The system is suitable for the precise demodulation of large-scale, high-Q-value microcavity sensor arrays, opening up new avenues for the application of integrated optical microcavity sensing, and has broad application potential in the fields of material detection, trace analysis, wearable physiological signal monitoring, etc.

[0041] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0042] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A fast demodulation system for large-scale on-chip microcavity arrays, characterized by: include: swept laser (1); A first optical fiber coupler (2) is used to receive the light source of the frequency-sweeping laser (1) and to divide the light source into a first light source and a second light source; A microcavity array transmission signal arm (100) is used to receive the first light source of the frequency-sweeping laser (1). The first light source enters the on-chip large array microcavity sensor device (5) after polarization processing, receives the disturbance of the external sensor signal, and converts it into an electrical signal to obtain a microcavity array transmission spectrum signal (101). Auxiliary interference reference arm (200): used for receiving the second light source of the frequency-sweeping laser (1), processing the second light source to obtain two coherent light beams with opposite phases, and then converting the coherent light beams into electrical signals to obtain auxiliary interference reference signals (201); A co-frequency trigger arm (300) is used to transmit a co-frequency trigger signal (301) emitted by the frequency sweep laser (1); A signal processing device (12) is used to collect the microcavity array transmission spectrum signal (101), the auxiliary interference reference signal (201) and the same-frequency trigger signal (301), and obtain a demodulated sensing signal after signal processing.

2. The fast demodulation system for on-chip large-scale microcavity arrays according to claim 1, characterized in that: The microcavity array transmission signal arm (100) comprises a first polarization controller (4), an on-chip large array microcavity sensor device (5), and a first photodetector (6) connected in sequence; the input end of the first polarization controller (4) is connected to the first output end of the first optical fiber coupler (2); and the output end of the first photodetector (6) is connected to a signal processing device (12).

3. The fast demodulation system for on-chip large-scale microcavity arrays according to claim 2, characterized in that: The auxiliary interference reference arm (200) comprises a second optical fiber coupler (7), an optical fiber delay line (8), a second polarization controller (9), a third optical fiber coupler (10) and a second photodetector (11); the input end of the second optical fiber coupler (7) is connected to the second output end of the first optical fiber coupler (2), the first output end of the second optical fiber coupler (7) is connected to the first input end of the third optical fiber coupler (10), the second output end of the second optical fiber coupler (7) is connected to the input end of the second polarization controller (9) after passing through the optical fiber delay line (8), the output end of the second polarization controller (9) is connected to the second input end of the third optical fiber coupler (10), the output end of the third optical fiber coupler (10) is connected to the input end of the second photodetector (11), and the output end of the second photodetector (11) is connected to the signal processing device (12).

4. The fast demodulation system for on-chip large-scale microcavity arrays according to claim 3, characterized in that: The microcavity array transmission signal arm (100) further includes an adjustable optical attenuator (3), and the first output end of the first optical fiber coupler (2) is connected to the first polarization controller (4) through the adjustable optical attenuator (3).

5. The fast demodulation system for on-chip large-scale microcavity arrays according to claim 3, characterized in that: The first optical fiber coupler (2) divides the light source into a first light source and a second light source according to a splitting ratio of N1:N2, and the value of N1 is greater than the value of N2.

6. The fast demodulation system for on-chip large-scale microcavity arrays according to claim 3, characterized in that: The second optical fiber coupler (7) splits the second light source into a third light source and a fourth light source at a splitting ratio of 1:

1.

7. The fast demodulation system for on-chip large-scale microcavity arrays according to any one of claims 3 to 6, characterized in that: The microcavity structure of the on-chip large array microcavity sensor device (5) includes a microring resonant cavity, a Fabry-Perot resonant cavity or a photonic crystal resonant cavity; and is made of chalcogenide materials.

8. The fast demodulation system for on-chip large-scale microcavity arrays according to claim 7, characterized in that: The first photodetector (6) is an avalanche photodetector; the second photodetector (11) is a balanced photodetector.

9. The fast demodulation system for on-chip large-scale microcavity arrays according to claim 6, characterized in that: The frequency sweeping laser (1), the first fiber coupler (2), the second fiber coupler (7), the fiber delay line (8), the second polarization controller (9), the third fiber coupler (10), the second photodetector (11), the first photodetector (6), the on-chip large array microcavity sensor device (5) and the first photodetector (6) are all connected via optical fibers; the frequency sweeping laser (1), the first photodetector (6) and the second photodetector (11) are all connected to the signal processing device (12) via cables; and the on-chip large array microcavity sensor device (5) is connected to the optical fiber via fiber end face coupling or grating vertical coupling.

10. A fast demodulation method for large-scale on-chip microcavity arrays, characterized in that: A fast demodulation system for an on-chip large-scale microcavity array according to any one of claims 1 to 9 comprises the following steps: S1. At the signal processing device (12), a microcavity array transmission spectrum signal (101), an auxiliary interference reference signal (201), and a co-frequency trigger signal (301) are obtained respectively; S2. performing signal alignment through cross-correlation operation, subtracting the delay difference between the microcavity array transmission spectrum signal (101), the auxiliary interference reference signal (201), and the same-frequency trigger signal (301), and performing filtering and denoising processing; S3. Based on the rising edge of the same-frequency trigger signal (301) of the sweep laser (1), the microcavity array transmission spectrum signal (101) and the auxiliary interference reference signal (201) are data-synchronized and sliced ​​into multiple sweep cycle segments, and each frame is cut into a complete sweep cycle; S4. extracting the reference phase of the auxiliary interference reference signal (201) in each frequency sweep cycle by Hilbert transform, which is used to characterize the nonlinearity of the frequency sweep process; calculating the instantaneous phase by the reference phase, and removing the phase jump by unwrapping operation; S5. Calculate the instantaneous frequency based on the time derivative of the reference phase and compare it with the expected frequency of an ideal linear frequency sweep to obtain the frequency deviation. S6. Based on the nonlinear characteristics of the instantaneous frequency, the microcavity array transmission spectrum signal (101) is non-uniformly resampled and the signal is remapped to a uniform frequency axis to obtain the compensated and corrected microcavity array transmission spectrum signal (101); S7. performing position identification and morphological resolution of the microcavity array resonance peak for each frame of the microcavity array transmission spectrum signal (101) after compensation correction; S8. Track the position or shape change of each microcavity resonance peak in each frame, and demodulate and read the external sensor signal.

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