A single micro-ring resonator based FBG tactile sensing real-time processing system

Abstract

The present application relates to the field of tactile sensing and integrated photonics technology, and particularly relates to a FBG tactile sensing real-time processing system based on a single micro-ring resonator, comprising a single-wavelength laser, a circulator, a FBG tactile sensor, a micro-ring resonator, an MPD with avalanche gain, a TIA, an ADC and a PC terminal, the wavelength of the laser falls within the 3dB bandwidth of the FBG sensor, and the micro-ring resonator is provided with an electric tuning structure to regulate the transmitted light intensity; when the electric tuning is fixed, signal demodulation is realized, and when the electric tuning is adjustable, convolution weighting is completed; after photoelectric conversion, amplification and analog-digital conversion, the signal is sent to the PC terminal for processing, and the system has compact structure and high real-time performance. In the present application, through the single micro-ring resonator with an electric tuning structure, integrated processing of tactile signal demodulation and convolution weighting is realized, and demodulation and feature extraction are completed in a single device, thereby shortening the processing link, reducing the cumulative delay and improving the real-time response speed of the system.

Description

Technical Field

[0001] This invention relates to the field of conceptual verification of tactile sensing and integrated photonics technology, and more particularly to a real-time FBG tactile sensing processing system based on a single microring resonator. Background Technology

[0002] Tactile sensing technology is a core underlying sensing technology in fields such as tactile feedback for intelligent robots, precision detection in minimally invasive medical procedures, and high-precision assembly in industry. Among these, tactile sensing technology based on fiber Bragg gratings (FBGs) has become one of the important research directions and mainstream application technologies in the field of high-precision tactile detection due to its outstanding advantages such as strong anti-electromagnetic interference capability, excellent environmental stability, high detection sensitivity, and small size and easy integration. Currently, FBG tactile sensing systems have formed a standardized signal processing technology framework, which corely covers four major stages: tactile light signal perception, wavelength demodulation, feature extraction, and tactile recognition. The wavelength demodulation stage is mostly implemented using mature electro-demodulation schemes such as spectrometers and fiber interferometers, while the convolutional feature extraction stage of tactile signals is mostly completed using general-purpose computing platforms such as GPUs. At the same time, integrated photonic devices, represented by single microring resonators, have been gradually applied to wavelength demodulation scenarios for FBG signals due to their ultra-fast response speed, high-precision light field control capability, and miniaturization integration advantages, providing a feasible technical path for the miniaturization and high-speed development of FBG tactile sensing systems.

[0003] Traditional FBG haptic sensing real-time processing systems mostly use separate electromodulation modules and convolution calculation modules. Due to the long signal processing link and the cumulative delay caused by serial transmission and processing of multiple links, the overall system processing cycle is long and the real-time response capability is insufficient. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides a real-time FBG tactile sensing system based on a single microring resonator, aiming to improve the problems of traditional FBG tactile sensing real-time processing systems, which mostly use discrete electromodulation modules and convolution calculation modules, easily resulting in long overall system processing cycles and insufficient real-time response capabilities.

[0005] This invention provides the following technical solution: a real-time processing system for FBG tactile sensing based on a single microring resonator includes a single-wavelength laser, a circulator, a reflective FBG (Fiber Bragg Grating) tactile sensor, a photodetector, a TIA (Trans-Impedance Amplifier), an ADC (Analog-to-Digital Converter), and a PC terminal; it also includes a single microring resonator; the output of the single-wavelength laser is optically connected to the first port of the circulator, the second port of the circulator is optically connected to the reflective FBG tactile sensor, and the third port of the circulator is optically connected to the optical input of the single microring resonator. The output terminal is sequentially connected to the PC terminal via the photodetector, TIA, and ADC; the output wavelength of the single-wavelength laser falls within the 3dB bandwidth range of the reflective FBG tactile sensor; the single microring resonator is equipped with an electrically tuned structure, which is used to change the effective refractive index of the waveguide of the single microring resonator to control the transmitted light intensity; when the electrically tuned structure is fixed, the transmitted light intensity of the single microring resonator changes with the reflected light intensity of the reflective FBG tactile sensor to achieve tactile signal demodulation; when the electrically tuned structure is adjustable, the transmitted light intensity changes with the tuning parameters of the electrically tuned structure to achieve tactile signal convolution weighting; the photodetector is an MPD (Avalanche Photodetector) with an avalanche gain module.

[0006] By adopting the above technical solution and designing a single micro-ring resonator with an electrically tuned structure, an integrated processing mechanism is achieved to demodulate tactile signals when the electrically tuned structure is in fixed operation and to perform convolutional weighting of tactile signals when it is in adjustable operation. This allows the entire process of demodulation and feature extraction of FBG tactile signals to be completed within a single device. This improves upon the problem that traditional FBG tactile sensing real-time processing systems mostly use separate electro-demodulation modules and convolutional calculation modules. Due to the long signal processing link and the cumulative delay caused by serial transmission and processing of multiple links, the overall system processing cycle is long and the real-time response capability is insufficient.

[0007] The present invention has the following beneficial effects:

[0008] 1. In this invention, by designing a single micro-ring resonator with an electrically tuned structure, an integrated processing mechanism is used to achieve tactile signal demodulation when the electrically tuned structure is in fixed operation and tactile signal convolution weighting when it is in adjustable operation. Thus, the entire process of demodulation and feature extraction of FBG tactile signals is completed within a single device. This improves upon the problem that traditional FBG tactile sensing real-time processing systems mostly use separate electro-demodulation modules and convolution calculation modules. Due to the long signal processing link and the cumulative delay caused by serial transmission and processing of multiple links, the overall system processing cycle is long and the real-time response capability is insufficient.

[0009] 2. In this invention, the optical signal output by a single microring resonator is photoelectrically converted by an MPD with an avalanche gain module, thereby improving the detection sensitivity and signal conversion accuracy of low-power optical signals. This improves the problem that traditional FBG tactile sensing systems mostly use ordinary photodetectors, which suffer from low output optical signal power of a single microring resonator and insufficient response capability of ordinary detectors to weak light signals, resulting in distortion of effective signal acquisition and poor signal integrity.

[0010] 3. In this invention, the current signal output by the MPD is amplified and matched by TIA, thereby converting the weak current signal into a voltage signal that is compatible with the input range of the ADC and suppressing environmental noise during transmission. This improves the problem that traditional FBG tactile sensing systems mostly use multi-stage discrete signal amplification and conditioning circuits. Due to the fact that multi-stage signal transmission is prone to introducing environmental noise and poor signal matching, the output signal has a low signal-to-noise ratio and insufficient accuracy of subsequent tactile recognition. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the optical path of a real-time FBG tactile sensing processing system based on a single microring resonator proposed in this invention.

[0012] Figure 2 Microscopic image of the electrically tuned structure of a single microring resonator in this invention;

[0013] Figure 3 This is a graph showing the relationship between the input voltage of the electrically tuned structure and the output light intensity of a single micro-ring resonator in this invention.

[0014] Figure 4 This is the reflectance spectrum of the reflective FBG tactile sensor in this invention;

[0015] Figure 5 This is a linear relationship curve between the pressure applied to the reflective FBG tactile sensor and the system output light intensity in this invention. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: In the first embodiment of the present invention, the present invention provides a real-time FBG tactile sensing processing system based on a single microring resonator. Please refer to [link to relevant documentation]. Figure 1 The system includes a single-wavelength laser, a circulator, a reflective FBG tactile sensor, a photodetector, a TIA, an ADC, and a PC terminal; it also includes a single microring resonator. The output of the single-wavelength laser is optically connected to the first port of the circulator, the second port of the circulator is optically connected to the reflective FBG tactile sensor, and the third port of the circulator is optically connected to the optical input of the single microring resonator. The optical output of the single microring resonator is connected to the PC terminal via the photodetector, TIA, and ADC in sequence. The output wavelength of the single-wavelength laser falls within the 3dB bandwidth of the reflective FBG tactile sensor. The single microring resonator is equipped with an electrically tuned structure, which is used to change the effective refractive index of the waveguide of the single microring resonator to control the transmitted light intensity. When the electrically tuned structure is fixed, the transmitted light intensity changes with the reflected light intensity of the reflective FBG tactile sensor to achieve tactile signal demodulation. When the electrically tuned structure is adjustable, the transmitted light intensity changes with the tuning parameters of the electrically tuned structure to achieve tactile signal convolution weighting. The photodetector is an MPD with an avalanche gain module.

[0018] Specifically, the single-wavelength laser is a 1550nm narrow-linewidth distributed feedback laser with an output power of 0~10mW; the circulator is a 1550nm three-port fiber optic circulator with an insertion loss ≤0.8dB; the reflective FBG tactile sensor has a center wavelength of 1550nm and a 3dB bandwidth of 0.2nm; the single microring resonator is an SOI-based integrated photonic device with a Q value ≥10^4; the MPD is a 1550nm InGaAs avalanche photodetector with an avalanche gain of 10~100 times; the TIA is a low-noise transimpedance amplifier with a bandwidth ≥10MHz; the ADC is a 12-bit or higher analog-to-digital converter with a sampling rate ≥1MS / s; and the PC terminal is a general-purpose industrial computer, which uses a single-wavelength laser... The device provides a stable single-wavelength incident light signal, ensuring the system receives an incident light source that meets the requirements of FBG tactile sensing. The circulator controls the unidirectional transmission path of the light signal, separating the incident and reflected light paths to prevent reflected light from interfering with the stable operation of the light source. The reflective FBG tactile sensor converts external tactile pressure into changes in optical signal characteristics, allowing external tactile signals to be converted into detectable optical signals. The photodetector converts the optical signal into a corresponding current signal, transforming the optical tactile signal into an electrical signal for subsequent processing. The TIA (Transient Amplifier) ​​handles the weak current signal input from the front end. The system amplifies and conditions weak electrical signals to a range suitable for subsequent devices. The ADC converts continuously changing analog electrical signals into discrete digital signals, transforming analog tactile signals into digital signals that can be processed by terminal devices. A PC terminal then processes the received digital signals and outputs the results, enabling final classification, recognition, and display of the tactile signals. A single microring resonator performs integrated optical processing on the light signals carrying tactile information, allowing the system to complete the core signal processing flow with a single integrated photonic device. This replaces traditional discrete demodulation and convolution modules, eliminating the need for serial processing in two stages. The structure, which uses a cumulative delay and optical connection between the output of a single-wavelength laser and the first port of a circulator, enables low-loss transmission of the optical signal output from the light source to the circulator, allowing the incident light signal to stably enter the optical path control unit. The structure, which uses the second port of the circulator to optically connect to a reflective FBG tactile sensor, enables transmission of the incident light signal to the tactile sensing unit and reception of the reflected light signal returned by the sensing unit, allowing the light signal to complete the round-trip transmission for tactile perception. The structure, which uses the third port of the circulator to optically connect to the optical input of a single micro-ring resonator, enables transmission of the reflected light signal carrying tactile information to the core optical processing unit, allowing the sensed light signal to enter subsequent processing stages.The link structure, which connects the optical output of a single microring resonator sequentially through a photodetector, TIA, ADC, and PC terminal, serves to construct a complete optical-electronic-digital signal processing link. This allows the processed tactile signal to be stably transmitted and converted from the optical domain to the digital domain. The parameter matching design, ensuring the output wavelength of the single-wavelength laser falls within the 3dB bandwidth of the reflective FBG tactile sensor, converts the wavelength shift caused by external forces into a linear change in reflected light intensity. This allows the wavelength change induced by touch to be converted into directly detectable light. The electrically tunable structure, using a single microring resonator, can modulate the optical properties of the microring waveguide, allowing for flexible control of the transmitted light intensity via electrical signals. This design, which alters the effective refractive index of the individual microring resonator to regulate transmitted light intensity, enables precise control of the microring's transmission characteristics. The microring can adjust the transmission ratio of the light signal according to operational requirements. When the electrically tunable structure is fixed, the transmitted light intensity changes with the reflected light intensity of the reflective FBG tactile sensor, thus achieving the demodulation mode for the tactile signal. This design enables the demodulation of tactile signals through micro-rings in a fixed operating state. This allows the system to directly demodulate tactile signals optically. Specifically, the fixed operating state involves inputting a fixed-amplitude DC voltage to the electrically tuned structure, locking the resonant wavelength of a single micro-ring resonator to a preset operating point. When the electrically tuned structure is adjustable, the transmitted light intensity varies with the tuning parameters of the structure, achieving a tactile signal convolution weighting working mode. This design also enables the extraction of tactile signal convolution features through micro-rings in adjustable operating states, allowing the system to directly demodulate tactile signals optically. A single device synchronously completes both demodulation and convolution weighting processing. The adjustable operating state specifically involves a pre-defined variable tuning voltage input to the electrical tuning structure, dynamically adjusting the transmission spectrum of a single micro-ring resonator according to the convolution kernel weights. By employing an MPD (Multi-Purpose Diode) with an avalanche gain module in the photodetector, the sensitivity for detecting weak light signals is improved. This allows the low-power optical signal output from the single micro-ring resonator to be converted into a corresponding electrical signal with high fidelity. This, in conjunction with a low-noise TIA (Transient Induction Algorithm) at the backend, enhances the overall signal-to-noise ratio (SNR) and addresses the issue of the weak light signal output from the micro-ring being easily overwhelmed by noise.

[0019] The substrate of a single microring resonator is a silicon-silicon dioxide-silicon layered structure. From bottom to top, the substrate consists of a bottom silicon layer, a middle silicon dioxide insulating layer, and a top silicon layer. The waveguide structure of the single microring resonator is etched on the top silicon layer. The waveguide structure is a single-mode transmission waveguide structure, which includes mutually coupled straight waveguides and ring waveguides. The first end of the straight waveguide serves as the optical input end of the single microring resonator, and the second end of the straight waveguide serves as the optical output end of the single microring resonator.

[0020] Specifically, the substrate of a single microring resonator is an SOI wafer consisting of a 200μm thick bottom silicon layer, a 2μm thick intermediate silicon dioxide insulating layer, and a 220nm thick top silicon layer; the waveguide structure has a width of 450nm and a height of 220nm, serving as a 1550nm band single-mode waveguide; the ring waveguide has a radius of 10μm, and the coupling distance between the straight waveguide and the ring waveguide is 200nm. The silicon-silicon dioxide-silicon layered structure of the substrate of the single microring resonator provides stable mechanical support and optical constraint for the microring optical structure, allowing the single microring resonator to... Fabrication is achieved using mature semiconductor processing technology, ensuring the mechanical stability and optical performance consistency of the device structure. The substrate, with its bottom layer of silicon, intermediate silicon dioxide insulating layer, and top layer of silicon, forms a high-refractive-index-difference total internal reflection optical confinement system. This allows the transmitted light field within the waveguide to be efficiently confined to the top silicon region, effectively reducing radiation loss, scattering loss, and thermal conduction loss during light transmission. The waveguide structure of a single microring resonator etched onto the top silicon precisely integrates the optical transmission structure with the substrate's optical system. The waveguide structure, relying on the high refractive index of the top silicon material, enables stable optical field confinement and transmission. As a single-mode transmission waveguide, it ensures the uniformity of the optical signal transmission mode, preventing multimode crosstalk and mode dispersion during transmission and resonance, thus guaranteeing the accuracy of subsequent intensity control and signal detection. The waveguide structure, including coupled straight and ring waveguides, forms the core of a micro-ring resonant optics system, allowing stable resonance within the ring waveguide. The resonant characteristics of the micro-ring enable precise and continuous control of transmitted light intensity. The first end of the straight waveguide serves as the optical input of a single micro-ring resonator, achieving low-loss coupling input of the incident light signal. This allows the incident light signal carrying tactile information to efficiently enter the optical structure of the single micro-ring resonator for processing. The second end of the straight waveguide serves as the optical output of the single micro-ring resonator, ensuring stable and low-loss output of the processed light signal. This allows the processed light signal to be efficiently transmitted to subsequent photoelectric detection and signal conditioning units.

[0021] The electrically tunable structure includes a heating layer and an electrode layer. The heating layer is an indium tin oxide thin film layer that covers the waveguide structure surface of a single microring resonator. The electrode layer is deposited on the surface of the heating layer and includes a chromium substrate layer and a gold conductive layer. The electrode layer has external pins for connecting to an external tuning power supply. The heating layer generates heat through the electrical energy input from the electrode layer, which can change the effective refractive index of the waveguide structure of the single microring resonator.

[0022] Specifically, the heating layer is a 100nm thick indium tin oxide (ITO) thin film prepared by magnetron sputtering, with a sheet resistance of 50 ohms per square. The electrode layer is a 10nm thick chromium substrate layer + a 100nm thick gold conductive layer prepared by electron beam evaporation. External pins with 100μm diameter gold pads are led out at both ends of the electrodes, adapting to a 0~5V DC tuning power supply. The electrically tunable structure, including the heating layer and the electrode layer, serves to construct a conversion system from electrical signal to thermal signal and then to optical characteristic modulation. This allows the optical characteristics of a single microring resonator to be flexibly and continuously modulated by an external electrical signal. The heating layer is made of indium tin oxide (ITO)... The indium tin oxide (ITO) thin film layer can achieve efficient electrothermal conversion while ensuring normal optical signal transmission. This allows the heating layer to efficiently convert input electrical energy into heat energy without interfering with the optical field transmission within the waveguide, avoiding the introduction of additional optical transmission losses. By covering the waveguide structure surface of a single microring resonator with the heating layer, it can accurately and efficiently conduct the generated heat to the waveguide structure, concentrating the heat on the waveguide region where refractive index adjustment is needed, reducing ineffective heat loss, and improving the response speed and accuracy of refractive index adjustment. The electrode layer deposited on the surface of the heating layer can also... The electrode layer provides a uniform and stable power input to the heating layer, enabling it to heat up evenly under the power supply of the electrode layer. This avoids waveguide refractive index modulation deviations caused by localized temperature unevenness. The electrode layer, consisting of a chromium base layer and a gold conductive layer, enhances the adhesion stability between the electrode layer and the heating layer while ensuring excellent conductivity. This allows the electrode layer to adhere stably to the heating layer surface for a long time, preventing detachment and delamination. It also enables low-loss power transmission. External pins leading out from the electrode layer connect to an external tuning power supply, facilitating the electrical tuning structure and external... The stable electrical connection of the tuned power supply enables the tuned electrical signal output from the external power supply to be transmitted stably and with low loss to the electrode layer and the heating layer, providing controllable electrical energy input for refractive index modulation. The electrical energy input through the electrode layer generates heat, which changes the effective refractive index of the waveguide structure of a single microring resonator. This allows for precise modulation of the waveguide optical resonance characteristics through the thermo-optical effect of silicon material, enabling continuous and precise modulation of the transmitted light intensity of a single microring resonator according to the input electrical signal. This provides a stable optical modulation basis for the demodulation and convolution weighted processing of tactile signals.

[0023] Please see Figure 2 and Figure 3The circulator is a three-port unidirectional optical transmission device. The first port of the circulator only allows optical signals to be transmitted unidirectionally from the single-wavelength laser to the inside of the circulator. The second port of the circulator only allows optical signals to be transmitted bidirectionally between the circulator and the reflective FBG tactile sensor. The third port of the circulator only allows optical signals to be transmitted unidirectionally from the inside of the circulator to a single microring resonator. The operating bandwidth of the circulator covers the output wavelength of the single-wavelength laser, the operating wavelength of the reflective FBG tactile sensor, and the resonant wavelength of the single microring resonator.

[0024] Specifically, the circulator has a working bandwidth of 1525nm~1565nm, a return loss ≥40dB, and a polarization-dependent loss ≤0.2dB. As a three-port unidirectional optical transmission device, the circulator can directionally control and isolate the transmission path of optical signals within the system, allowing incident and reflected light to complete directional transmission along preset paths and avoiding crosstalk between optical signals from different transmission directions. The first port of the circulator allows only unidirectional transmission of optical signals from the single-wavelength laser into the circulator, achieving unidirectional input and reverse isolation of the incident light signal. This ensures that the optical signal output from the single-wavelength laser can stably enter the circulator while effectively blocking the backflow of optical signals from the circulator back to the single-wavelength laser, preventing backlight interference with the laser's output wavelength and power stability. The second port of the circulator allows only bidirectional transmission of optical signals between the circulator and the reflective FBG tactile sensor, achieving bidirectional transmission control of incident light signal output and reflected light signal recovery, ensuring stable input of the incident light signal. The light signal is transmitted to a reflective FBG tactile sensor for tactile perception. Simultaneously, the reflected light signal carrying tactile information returned by the FBG tactile sensor can be recovered back into the circulator, completing the round-trip transmission of the optical signal. The circulator's third port allows only unidirectional transmission of the optical signal from inside the circulator to a single microring resonator, achieving directional output and reverse isolation of the reflected light signal carrying tactile information. This ensures stable transmission of the reflected light signal within the circulator to the single microring resonator for subsequent optical processing, while effectively blocking the entry of the reverse-transmitted optical signal into the circulator, preventing interference with the front-end optical signal transmission. The circulator's operating bandwidth covers the output wavelength of the single-wavelength laser, the operating wavelength of the reflective FBG tactile sensor, and the resonant wavelength of the single microring resonator, ensuring low-loss and stable transmission of the optical signal throughout the entire link. This prevents additional insertion loss and bandwidth limitations for all operating wavelengths of the optical signal when transmitted through the circulator, guaranteeing the integrity and consistency of the entire optical signal transmission.

[0025] The center wavelength of the reflective FBG tactile sensor matches the resonant wavelength of a single microring resonator. The 3dB bandwidth of the reflective FBG tactile sensor covers the output wavelength of a single-wavelength laser. The grating period of the reflective FBG tactile sensor deforms with the external force, which can change its reflected light wavelength and reflected light intensity.

[0026] Specifically, the reflective FBG tactile sensor exhibits a strain sensitivity of no less than 1 pm / με and a pressure sensitivity of no less than 0.3 nm / N, capable of detecting tactile pressures from 0 to 10 N. The deviation between the center wavelength and the resonant wavelength of a single microring resonator is ≤50 pm. This parameter matching design, where the center wavelength of the reflective FBG tactile sensor is matched to the resonant wavelength of a single microring resonator, ensures precise matching of the optical characteristics between the tactile sensing unit and the back-end optical processing unit. This allows the reflected light signal carrying tactile information to stably correspond to the resonant operating range of the single microring resonator, guaranteeing the accuracy and consistency of subsequent optical signal processing. Furthermore, the parameter matching design, where the 3 dB bandwidth of the reflective FBG tactile sensor covers the output wavelength of a single-wavelength laser, converts the wavelength shift of the grating into a detectable change in light intensity. This allows the wavelength shift caused by external force to be linearly converted into a corresponding change in reflected light intensity, achieving a stable conversion from external tactile physical quantities to detectable optical characteristics. The conversion, achieved through the structural design of the reflective FBG tactile sensor where the grating period deforms with the applied external force, effectively converts the physical quantity of external tactile pressure into changes in the physical structure of the grating. This allows the applied tactile pressure to be precisely converted into periodic structural deformation within the grating core, providing a stable physical basis for subsequent changes in optical characteristics. Furthermore, the reflective FBG tactile sensor's optical characteristic of altering the wavelength of its reflected light through grating periodic deformation converts the magnitude of tactile pressure into a quantifiable wavelength shift. This allows changes in external tactile pressure to be encoded as a shift in the center wavelength of reflected light, achieving precise optical encoding of the tactile signal. Finally, the reflective FBG tactile sensor's optical characteristic of altering the intensity of its reflected light through grating periodic deformation converts changes in tactile pressure into directly detectable changes in light intensity. This allows changes in external tactile pressure to directly correspond to changes in the intensity of reflected light, facilitating demodulation and feature extraction of the tactile signal by a single microring resonator at the back end.

[0027] Please see Figure 4 and Figure 5 The single-wavelength laser is a distributed feedback laser. The single-wavelength laser outputs a single-mode beam with a fixed wavelength. The output power of the single-wavelength laser matches the reflected light intensity detection range of the reflective FBG tactile sensor.

[0028] Specifically, the single-wavelength laser has a linewidth ≤100kHz, wavelength stability ≤±5pm / ℃, and an adjustable output power range of 0~10mW, matching the 0~5mW reflected light intensity detection range of the reflective FBG tactile sensor. By using a distributed feedback laser, the single-wavelength laser provides a high-wavelength stability, narrow linewidth, and low-noise incident light signal, enabling the system to obtain a reference light source with stable output characteristics and strong resistance to environmental interference. This effectively reduces the adverse effects of wavelength fluctuations of the light source itself on the accuracy of subsequent tactile signal detection. The single-wavelength laser outputting a fixed-wavelength single-mode beam ensures the consistency of the incident light signal wavelength and the single transmission mode, allowing the incident light signal to stably fall into the reflective FBG. Within the 3dB bandwidth of the tactile sensor, issues such as multimode crosstalk and modal dispersion do not arise, providing a stable and unified optical benchmark for detecting light intensity changes caused by subsequent tactile signals. By matching the output power of a single-wavelength laser with the reflected light intensity detection range of the reflective FBG tactile sensor, the incident light power can be precisely matched with the working range of the sensing unit and subsequent photoelectric detection unit. This ensures that the power of the reflected light signal returned by the reflective FBG tactile sensor after being modulated by external force can be stably within the linear detection range of the downstream photoelectric detection device, avoiding detection saturation distortion caused by excessive light power or effective signal being overwhelmed by noise due to excessive light power, thus guaranteeing the linearity, sensitivity, and accuracy of tactile signal detection.

[0029] The MPD's response wavelength covers the output wavelength range of a single microring resonator. The MPD's electrical output terminal is electrically connected to the TIA's electrical input terminal via a shielded transmission line. The TIA's input current range matches the MPD's output current range, and the TIA's output voltage range matches the ADC's analog input voltage range. The TIA is a low-noise transimpedance amplifier.

[0030] Specifically, the MPD has a response wavelength range of 1200nm~1600nm, a responsivity ≥0.9A / W, and a bandwidth ≥10MHz; the shielded transmission line is a 50Ω impedance-matched coaxial shielded cable with a length ≤10cm; the TIA input current range is 1nA~1mA, the output voltage range is 0~3.3V, and the input reference noise current is ≤5pA / √Hz. By covering the output wavelength range of a single microring resonator with the MPD's response wavelength, it effectively achieves photoelectric response for the entire operating wavelength range of the single microring resonator's output, enabling the single... The optical signal carrying tactile information output by the micro-ring resonator can be completely and faithfully converted into a corresponding current signal without the problems of response failure or reduced conversion efficiency caused by wavelength mismatch. Connecting the electrical output of the MPD to the electrical input of the TIA via a shielded transmission line reduces external electromagnetic interference introduced during signal transmission. This allows the weak current signal output by the MPD to be transmitted to the input of the TIA with low loss and low interference, avoiding interference and distortion caused by the external electromagnetic environment and ensuring the integrity of the effective signal. Matching the input current range of the A to the output current range of the MPD enables precise adaptation of the operating ranges of the preceding and following electrical components. This ensures that the full-range current signal output by the MPD can be effectively received and linearly amplified by the TIA, preventing saturation distortion caused by the input signal exceeding the amplification range or insufficient amplification due to low signal amplitude. Matching the output voltage range of the TIA to the analog input voltage range of the ADC enables precise adaptation of the operating ranges of the signal conditioning unit and the subsequent analog-to-digital conversion unit. This ensures that the voltage signal amplified and conditioned by the TIA falls completely within the linear sampling range of the ADC, guaranteeing the linearity and sampling accuracy of the analog-to-digital conversion process. This avoids truncation distortion caused by the signal amplitude exceeding the sampling range or insufficient sampling resolution due to low amplitude. As a low-noise transimpedance amplifier, the TIA effectively suppresses inherent circuit noise while amplifying weak current signals with high gain. This prevents excessive noise from drowning out the weak effective signal during amplification, effectively improving the signal-to-noise ratio of the output electrical signal and providing a high-fidelity signal foundation for subsequent analog-to-digital conversion and tactile signal recognition.

[0031] The ADC is an analog-to-digital converter with a USB communication interface. The ADC establishes a wired communication connection with the PC terminal through the USB communication interface. The PC terminal has data processing software installed. The data processing software is used to receive the digital signals transmitted by the ADC. The digital signals correspond to the voltage signals output by the TIA. The data processing software has a built-in tactile pressure level classification algorithm.

[0032] Specifically, the ADC is a 16-bit resolution analog-to-digital converter with a maximum sampling rate of 2MS / s, integrating a USB 2.0 full-speed communication interface, and an analog input voltage range of 0~3.3V. The data processing software has data receiving, buffering, and preprocessing functions. The built-in tactile pressure level classification algorithm can achieve 10 levels of tactile pressure recognition within the range of 0~10N. The ADC, as an analog-to-digital converter with a USB communication interface, converts analog electrical signals into digital signals and integrates a standardized data transmission channel. This allows the TIA-conditioned analog tactile signal to be effectively converted into a digital signal while possessing universal wired data transmission capabilities, simplifying the system's signal transmission link structure. Establishing a wired communication connection between the ADC and the PC terminal via the USB interface enables stable, high-speed, and interference-resistant wired transmission of digital signals. This allows the ADC-converted digital tactile signal to be transmitted to the PC terminal with low loss and high integrity, avoiding signal delay, packet loss, and external interference problems that are common in wireless transmission, ensuring the real-time performance and stability of signal transmission. The data processing software installed on the PC terminal provides a standardized operating medium and processing platform for subsequent processing of the tactile signal. This system enables the digital tactile signals transmitted to the PC terminal to be systematically processed according to preset logic, eliminating the need for a dedicated hardware processing platform. This enhances the system's versatility and adaptability to various scenarios. The conversion design, which corresponds the digital signal to the voltage signal output by the TIA, ensures a linear relationship between the digital signal and the original analog tactile signal. This allows the converted digital signal to accurately reproduce the amplitude variation pattern of the analog voltage signal output by the TIA, guaranteeing the fidelity and accuracy of the tactile signal conversion. The data processing software, used to receive the digital signal transmitted by the ADC, ensures stable reception and orderly buffering of the digital tactile signal. This allows the continuously transmitted digital signal from the ADC to be received and temporarily stored completely and orderly, avoiding data loss and out-of-order issues during signal transmission. This provides a complete data source for subsequent signal processing. The built-in tactile pressure level classification algorithm in the data processing software performs feature analysis and pressure level identification on the received digital tactile signal. This allows the tactile information carried in the digital signal to be interpreted into the corresponding tactile pressure level result, completing the entire process from the original sensing signal to the directly applicable tactile recognition result, and realizing the system's complete tactile sensing and detection function.

[0033] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A real-time processing system for FBG tactile sensing based on a single microring resonator, comprising a single-wavelength laser, a circulator, a reflective FBG tactile sensor, a photodetector, a TIA, an ADC, and a PC terminal; characterized in that, It also includes a single microring resonator; the output of the single-wavelength laser is optically connected to the first port of the circulator, the second port of the circulator is optically connected to the reflective FBG tactile sensor, and the third port of the circulator is optically connected to the optical input of the single microring resonator. The optical output of the single microring resonator is sequentially connected to the PC terminal via the photodetector, TIA, and ADC. The output wavelength of the single-wavelength laser falls within the 3dB bandwidth of the reflective FBG tactile sensor. The single microring resonator is equipped with an electrically tuned structure, which is used to change the effective refractive index of the waveguide of the single microring resonator to control the transmitted light intensity. When the electrically tuned structure is fixed, the transmitted light intensity of the single microring resonator changes with the reflected light intensity of the reflective FBG tactile sensor to achieve tactile signal demodulation. When the electrically tuned structure is adjustable, the transmitted light intensity changes with the tuning parameters of the electrically tuned structure to achieve tactile signal convolution weighting. The photodetector is an MPD with an avalanche gain module.

2. The FBG tactile sensing real-time processing system based on a single microring resonator according to claim 1, characterized in that, The substrate of the single microring resonator is a silicon-silicon dioxide-silicon layered structure. The substrate has a bottom silicon layer, an intermediate silicon dioxide insulating layer, and a top silicon layer arranged sequentially from bottom to top. The waveguide structure of the single microring resonator is etched on the top silicon layer. The waveguide structure is a single-mode transmission waveguide structure, which includes a straight waveguide and a ring waveguide coupled to each other. The first end of the straight waveguide serves as the optical input end of the single microring resonator, and the second end of the straight waveguide serves as the optical output end of the single microring resonator.

3. The FBG tactile sensing real-time processing system based on a single microring resonator according to claim 2, characterized in that, The electrically tunable structure includes a heating layer and an electrode layer. The heating layer is an indium tin oxide thin film layer that covers the waveguide structure surface of the individual microring resonator. The electrode layer is deposited on the surface of the heating layer and includes a chromium substrate layer and a gold conductive layer. The electrode layer has external pins for connecting to an external tuning power supply. The heating layer generates heat through the electrical energy input from the electrode layer, which can change the effective refractive index of the waveguide structure of the individual microring resonator.

4. The FBG tactile sensing real-time processing system based on a single microring resonator according to claim 1, characterized in that, The circulator is a three-port unidirectional optical transmission device. The first port of the circulator only allows optical signals to be transmitted unidirectionally from the single-wavelength laser to the interior of the circulator. The second port of the circulator only allows optical signals to be transmitted bidirectionally between the circulator and the reflective FBG tactile sensor. The third port of the circulator only allows optical signals to be transmitted unidirectionally from the interior of the circulator to the single microring resonator. The operating bandwidth of the circulator covers the output wavelength of the single-wavelength laser, the operating wavelength of the reflective FBG tactile sensor, and the resonant wavelength of the single microring resonator.

5. The FBG tactile sensing real-time processing system based on a single microring resonator according to claim 1, characterized in that, The center wavelength of the reflective FBG tactile sensor matches the resonant wavelength of the single microring resonator. The 3dB bandwidth of the reflective FBG tactile sensor covers the output wavelength of the single-wavelength laser. The grating period of the reflective FBG tactile sensor deforms with the external force, thereby changing its reflected light wavelength and intensity.

6. The FBG tactile sensing real-time processing system based on a single microring resonator according to claim 1, characterized in that, The single-wavelength laser is a distributed feedback laser, which outputs a single-mode beam with a fixed wavelength. The output power of the single-wavelength laser matches the reflected light intensity detection range of the reflective FBG tactile sensor.

7. The FBG tactile sensing real-time processing system based on a single microring resonator according to claim 1, characterized in that, The response wavelength of the MPD covers the output wavelength range of the single microring resonator. The electrical output terminal of the MPD is electrically connected to the electrical input terminal of the TIA through a shielded transmission line. The input current range of the TIA matches the output current range of the MPD. The output voltage range of the TIA matches the analog input voltage range of the ADC. The TIA is a low-noise transimpedance amplifier.

8. The FBG tactile sensing real-time processing system based on a single microring resonator according to claim 1, characterized in that, The ADC is an analog-to-digital converter with a USB communication interface. The ADC establishes a wired communication connection with the PC terminal through the USB communication interface. The PC terminal is equipped with data processing software, which is used to receive the digital signal transmitted by the ADC. The digital signal corresponds to the voltage signal output by the TIA. The data processing software has a built-in tactile pressure level classification algorithm.

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