Narrow-bandwidth photon temperature sensing chip and large-scale parallel topology system

Abstract

The invention relates to the technical field of photon sensing chip temperature measurement, in particular to a narrow-bandwidth photon temperature sensing chip and a large-scale parallel topological system.The sensing chip comprises a silicon-on-insulator platform, and a deep-etching ridge-type waveguide Bragg grating is arranged on the silicon-on-insulator platform; the deep-etching ridge-type waveguide Bragg grating comprises a ridge waveguide and slab waveguides located on the two sides of the ridge waveguide. The ridge waveguide and the slab waveguide form a deep etching structure which is used for constraining a light field in a core area of the ridge waveguide; grating modulation structures are arranged at the two ends, away from the ridge waveguide, of the slab waveguide, and each grating modulation structure comprises a plurality of grooves which are periodically distributed at intervals in the light transmission direction parallel to the ridge waveguide; and the grating modulation structure generates a weak coupling effect, so that the 3dB bandwidth of the reflection spectrum of the sensing chip is less than or equal to a set bandwidth threshold. According to the invention, the problems of inter-channel spectrum overlapping and crosstalk generated by a traditional broadband grating sensor during temperature drift are effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of photonic sensing chip temperature measurement technology, specifically to a narrow-bandwidth photonic temperature sensing chip and a large-scale parallel topology system. Background Technology

[0002] As the core infrastructure for energy transmission and distribution in modern society, the safe and stable operation of the power grid plays a vital role in national economic and social stability. With the large-scale integration of new energy sources and the rapid expansion of the electricity market, the complexity and risks of power grid operation have increased significantly. Key power equipment within the grid (such as converter valves and their internal power devices) generates high temperatures under long-term high-speed operation, which not only directly affects device performance and lifespan but also has the potential to trigger cascading failures leading to system paralysis. Therefore, temperature monitoring of power electronic equipment is particularly important.

[0003] Traditional measurement methods primarily rely on fiber Bragg gratings (FBGs) for temperature monitoring of internal components. However, FBGs are susceptible to external vibrations and mechanical stress, leading to significant reductions in measurement accuracy and system reliability. With the rapid development of silicon photonics integrated circuit technology, waveguide grating (WBG) sensors, with their small size, high stability, and good anti-interference capabilities, have provided a new technological path for monitoring power grid equipment and have become an important development direction. However, the use of WBG sensors for temperature monitoring still faces numerous challenges, including complex wiring, unsuitable reflection characteristics for high-density, multi-node parallel networking, and limited system scalability, preventing the realization of large-scale parallel sensor networks. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a narrow-bandwidth photonic temperature sensing chip and a large-scale parallel topology system. The specific technical solution adopted is as follows: In a first aspect, the present invention provides a narrow-bandwidth photonic temperature sensing chip, the sensing chip comprising a silicon-on-insulator platform, on which a deeply etched ridge waveguide Bragg grating is disposed; the deeply etched ridge waveguide Bragg grating comprises a ridge waveguide and planar waveguides located on both sides of the ridge waveguide; the ridge waveguide and the planar waveguide form a deeply etched structure for confining the optical field to the core region of the ridge waveguide; grating modulation structures are provided at both ends of the planar waveguide away from the ridge waveguide, the grating modulation structures comprising a plurality of grooves spaced apart and periodically distributed along the optical transmission direction parallel to the ridge waveguide; the grating modulation structures generate a weak coupling effect, making the 3dB bandwidth of the reflection spectrum of the sensing chip less than or equal to a set bandwidth threshold to maintain narrow-bandwidth characteristics.

[0005] In conjunction with the first aspect above, in some possible implementations, the cross-sectional dimensions of the deeply etched ridge waveguide Bragg grating are configured as follows: a total height of 220 nm, a ridge waveguide width of 500 nm, a planar waveguide height of 50 nm, and a planar waveguide total width of 1000 nm.

[0006] In conjunction with the first aspect above, in some possible implementations, the grating period, grating duty cycle of the grating modulation structure, and etching depth of the deep etching structure are configured as adjustable parameters to adapt to different target operating wavelengths.

[0007] In conjunction with the first aspect above, in some possible implementations, the target operating band includes at least the O-band and the C-band. When the operation of the deeply etched ridge waveguide Bragg grating is extended to the C-band, the etching depth of the deeply etched structure is 170 nm, the modulation depth of the grating modulation structure is 60 nm, the grating period length of the grating modulation structure is 305.9 nm, the grating duty cycle of the grating modulation structure is 0.5, and the total number of grating periods of the grating modulation structure is 25000, so as to achieve a peak reflectivity higher than a set reflectivity threshold.

[0008] In conjunction with the first aspect above, in some possible implementations, the silicon-on-insulator platform includes a bottom silicon substrate, a buried oxide layer, and a top silicon layer distributed sequentially from bottom to top, and a silicon dioxide cladding is covered on the top silicon layer. The deeply etched ridge waveguide Bragg grating is formed in the top silicon layer. The bottom silicon substrate has a thickness of 725 μm and a width of 1 mm. The silicon dioxide cladding has a thickness of 2 μm and a refractive index of 1.4445. The top silicon layer is made of Si, has a thickness of 0.22 μm, and a refractive index of 3.4763.

[0009] Secondly, the present invention also provides a large-scale parallel topology system, the system comprising a broadband light source, a circulator, an optical path gating module, a wavelength division multiplexing (WDM) module, a sensing network, and a signal demodulation module; the broadband light source is configured to provide a broadband optical signal, the optical path gating module is configured to perform time-division multiplexing gating on the broadband optical signal passing through the circulator and output it to one of the multiple optical path branches; the WDM module comprises multiple sets of arrayed waveguide gratings, each set of arrayed waveguide gratings connected to one of the optical path branches, and is configured to distribute the input optical signal to multiple wavelength channels; the sensing network comprises multiple narrow-bandwidth photonic temperature sensing chips as described in any of the above claims, the sensing chips being respectively connected to each wavelength channel of the arrayed waveguide gratings; wherein the sensing chips connected to different wavelength channels of the same set of arrayed waveguide gratings are configured with different grating periods to match the corresponding channel center wavelength; the signal demodulation module is configured to receive the optical signal reflected by the sensing chip and analyze the wavelength shift of the received optical signal to determine the temperature change.

[0010] In conjunction with the second aspect above, in some possible implementations, the channel spacing of the arrayed waveguide grating is set to a preset spacing value, which is configured to be greater than the maximum wavelength drift of the sensing chip within a preset operating temperature rise range, so as to isolate signal crosstalk between adjacent channels.

[0011] In conjunction with the second aspect above, in some possible implementations, the optical path gating module includes a MEMS-type optical switch configured for millisecond-level or sub-millisecond-level switching.

[0012] In conjunction with the second aspect above, in some possible implementations, the system further includes a monitoring terminal, which is configured to control the timing of the optical path selection module, acquire wavelength data output by the signal demodulation module, and realize real-time temperature distribution display based on the optical path branches determined by the timing and the wavelength channels corresponding to the wavelength data.

[0013] In conjunction with the second aspect above, in some possible implementations, the signal demodulation module includes a spectral analysis unit, a photoelectric conversion unit, and a signal processing unit; the monitoring terminal includes a host computer and a display screen.

[0014] This invention offers the following advantages: By employing a deeply etched ridge-type waveguide Bragg grating structure, and utilizing the grating modulation structure on both sides of the planar waveguide to generate a weak coupling effect, the 3dB bandwidth of the sensor chip's reflection spectrum is compressed to an extremely narrow range. This narrow bandwidth characteristic can achieve precise matching with the arrayed waveguide grating in the wavelength division multiplexing module, effectively avoiding the inter-channel spectral overlap and crosstalk problems caused by temperature drift in traditional broadband grating sensors, ensuring the independence and high signal-to-noise ratio of each wavelength channel signal. Simultaneously, by utilizing the optical path gating module and the arrayed waveguide grating, a single broadband light source and demodulation module are time-division multiplexed into sub-sensor networks of multiple arrayed waveguide gratings, resulting in a multiplex expansion of the total system node capacity, easily achieving large-scale networking of hundreds of points or more. This architecture significantly reduces the number of expensive light sources and demodulation devices, substantially lowering the cost of single-point monitoring, while simplifying the wiring complexity within high-voltage power equipment and improving system integration and maintenance convenience. Attached Figure Description

[0015] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a large-scale parallel topology system according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of silicon-on-insulator (SOI) according to an embodiment of the present invention; Figure 3 This is a top view of the ridge waveguide grating structure according to an embodiment of the present invention; Figure 4 This is an overall schematic diagram of a narrow-bandwidth photonic temperature sensing chip according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the single-mode field of the existing rectangular waveguide of the present invention; Figure 6 This is a schematic diagram of the single-mode field of a ridge waveguide according to an embodiment of the present invention; Figure 7 These are grating reflection spectra at different temperatures according to embodiments of the present invention; Figure 8 Temperature sensitivity characteristics of the photonic sensing chip in this embodiment of the invention; Figure 9 This is a schematic diagram of the overall structure of the arrayed waveguide grating according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the input coupler according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the output coupler according to an embodiment of the present invention; Figure 12 This is a spectrum of the output channel of the arrayed waveguide grating according to an embodiment of the present invention; Wherein: 1 is the silicon waveguide core layer, 2 is the silicon dioxide cladding, 3 is the buried oxide layer, 4 is the silicon substrate, 5 is the waveguide sidewall boundary, 6 is the planar region outside the ridge, 7 is the phase modulation array waveguide, 8 is the input waveguide, 9 is the input coupling unit, 10 is the output waveguide, and 11 is the output coupling unit. Detailed Implementation

[0017] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0018] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the invention. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention.

[0019] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0020] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0021] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0022] Although operations or steps are described in a specific order in the accompanying drawings in the embodiments of the present invention, this should not be construed as requiring these operations or steps to be performed in the specific order or serial order shown, or requiring all of the shown operations or steps to be performed to obtain the desired result. In the embodiments of the present invention, these operations or steps may be performed serially; they may be performed in parallel; or a portion of these operations or steps may be performed.

[0023] Furthermore, it is understood that the data involved in the technical solutions of this invention (including but not limited to the data itself, the acquisition or use of the data) shall comply with the requirements of relevant laws, regulations, and provisions. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] Narrow-bandwidth photonic temperature sensing chip example: The following will provide a detailed description of a narrow-bandwidth photonic temperature sensing chip provided by an embodiment of the present invention, with reference to the accompanying drawings.

[0025] Figure 4 This diagram illustrates the structure of a narrow-bandwidth photonic temperature sensing chip according to an embodiment of the present invention. Figure 4 As shown, the sensing chip includes a silicon-on-insulator platform, on which a deeply etched ridge-type waveguide Bragg grating is disposed. The deeply etched ridge-type waveguide Bragg grating includes a ridge waveguide and planar waveguides located on both sides of the ridge waveguide. The ridge waveguide and the planar waveguide form a deeply etched structure for confining the optical field to the core region of the ridge waveguide. Grating modulation structures are provided at both ends of the planar waveguide away from the ridge waveguide. The grating modulation structures include multiple grooves spaced apart and periodically distributed along the optical transmission direction parallel to the ridge waveguide. The grating modulation structures generate a weak coupling effect, making the 3dB bandwidth of the reflected spectrum of the sensing chip less than or equal to a set bandwidth threshold to maintain narrow bandwidth characteristics.

[0026] In the aforementioned narrow-bandwidth photonic temperature sensing chip, a deeply etched ridge-type waveguide Bragg grating is set on a silicon-on-insulator (SOI) platform compatible with mature CMOS technology. By confining the light field to the core region under the ridge, sidewall coupling is suppressed. Furthermore, a grating modulation structure is constructed on both sides of the planar waveguide to achieve a 3dB reflection bandwidth ≤ a set bandwidth threshold. For example, if the set bandwidth threshold is 0.25nm, the narrow bandwidth characteristic can be achieved. At the same time, the temperature sensitivity is approximately 72pm / °C, which can effectively suppress sidewall coupling and reduce channel crosstalk.

[0027] In one specific example, the silicon-on-insulator platform comprises, from bottom to top, a bottom silicon substrate, a buried oxide layer, and a top silicon layer, with a silicon dioxide cladding covering the top silicon layer; a deeply etched ridge waveguide Bragg grating is formed in the top silicon layer; the bottom silicon substrate has a thickness of 725 μm and a width of 1 mm; the silicon dioxide cladding has a thickness of 2 μm and a refractive index of 1.4445; the top silicon layer is made of Si, has a thickness of 0.22 μm, and a refractive index of 3.4763.

[0028] Specifically, the aforementioned narrow-bandwidth photonic temperature sensing chip is manufactured using a silicon-on-insulator (SOI) material system compatible with mature CMOS processes. The device layer is constructed by introducing an insulating layer onto a silicon substrate. The SOI structure consists of three layers: a bottom silicon substrate, a buried oxide layer, and a top silicon layer, with a silicon dioxide cladding layer covering the top silicon layer. A schematic diagram of the SOI cross-section is shown below. Figure 2 As shown, 1 represents the top silicon layer, made of Si, with a thickness of 0.22 μm and a refractive index of 3.4763, used to form the silicon waveguide core layer for a deeply etched ridge waveguide Bragg grating; 2 represents the silicon dioxide cladding, with a thickness of 2 μm; 3 represents the buried oxide layer; and 4 represents the bottom silicon substrate, with a thickness of 725 μm and a width of 1 mm. Due to the high refractive index contrast between the silicon waveguide core layer and the silicon dioxide cladding material, the optical signal is confined to the core layer for transmission, greatly reducing the device size.

[0029] In a specific example, the cross-sectional dimensions of the deeply etched ridge waveguide Bragg grating are configured as follows: total height of 220 nm, width of the ridge waveguide of 500 nm, height of the planar waveguide of 50 nm, and total width of the planar waveguide of 1000 nm.

[0030] Specifically, a top view of a deeply etched ridge waveguide Bragg grating is shown below. Figure 3 As shown in the diagram, the ridge waveguide grating structure is as follows: Figure 4 As shown, some parameters of the deeply etched ridge waveguide Bragg grating are configured as follows: Slabwidth. The ridge waveguide width is 1000nm. The wavelength is 500nm, and the total chip height H is 220nm, ensuring that the waveguide operates in single-mode.

[0031] In a specific example, the grating period, grating duty cycle of the grating modulation structure, and etching depth of the deep etching structure are configured as adjustable parameters to adapt to different target operating wavelengths.

[0032] Specifically, by adjusting parameters such as grating period length, duty cycle, or etching depth, the sensor chip can be extended to different operating bands, including O-band or C-band.

[0033] In a specific example, when the deep-etched ridge waveguide Bragg grating is extended to the C-band, the etching depth of the deep-etched structure is 170 nm, the modulation depth of the grating modulation structure is 60 nm, the grating period length of the grating modulation structure is 305.9 nm, the grating duty cycle of the grating modulation structure is 0.5, and the total number of grating periods of the grating modulation structure is 25000, so as to achieve a peak reflectivity higher than the set reflectivity threshold.

[0034] Specifically, by setting specific parameters such as the etching depth of the deep etching structure, the modulation depth of the grating modulation structure, the grating period length, the grating duty cycle, the total number of grating periods, and the total length, the operation of the deep-etched ridge waveguide Bragg grating can be extended to the C-band, while ensuring that the peak reflectivity is ≥ 95% of the set reflectivity threshold and that it maintains narrow bandwidth characteristics. For example, Figure 3 and Figure 4 As shown, the other parameters of this deeply etched ridge waveguide Bragg grating are configured as follows: grating period length The aperture is 305.9 nm, the etching depth d is 170 nm, the grating duty cycle is 0.5, the total number of grating periods N is 25000, and the modulation depth is... With a wavelength of 60nm and a total length of approximately 7.7mm, this length ensures both the high peak reflectivity of the deeply etched ridge waveguide grating sensor chip and an extremely narrow reflection bandwidth, thus meeting the networking requirements of large-scale parallel sensor networks under high-voltage power environments.

[0035] In a traditional rectangular waveguide structure, the optical field mode diagram is as follows: Figure 5 As shown, the electric field energy of the fundamental transverse electric mode (TE mode) extends significantly to near the waveguide sidewall boundary 5. This close overlap causes even small aggregate undulations or ripples on the sidewalls to produce strong optical perturbation effects. These strong perturbation effects typically manifest as non-negligible scattering loss or highly efficient inter-mode coupling, which is detrimental to stable, low-loss optical signal transmission, and the coupling coefficient... While a larger value can reduce the number of grating periods N and increase reflectivity, it can also reduce the number of grating periods N and increase reflectivity. ,in, The coupling coefficient is... While the length of the grating device is limited, the reflection bandwidth, typically reaching tens of nanometers, is unsuitable for wavelength division multiplexing (WDM) systems. Specifically, in arrayed waveguide grating applications, the wide bandwidth of the sensor chip leads to channel overlap: assuming an arrayed waveguide grating channel spacing of 2.4 nm, a slight change in external temperature causes a sharp shift in the reflection spectrum, resulting in severe channel crosstalk, significantly reducing multiplexing capability, and making it unsuitable for large-scale parallel sensor networks.

[0036] and Figure 5 Compared to the light field modes in [the text], Figure 6 This is a schematic diagram of the ridge waveguide mode field according to an embodiment of the present invention. Figure 6It is evident that by deeply etching a ridge-type waveguide Bragg grating, most of the optical field energy is efficiently confined to the core region below the ridge structure. Simultaneously, the optical field intensity in the flat plate region 6 located outside the ridge is significantly weakened. Therefore, constructing a corrugated structure on both sides of this low-intensity region fundamentally suppresses the coupling between the optical mode field and the modulation structure, reducing the effective refractive index of the device and decreasing the coupling coefficient. The significant reduction leads to a decrease in reflection bandwidth The reduction in bandwidth enables narrow-bandwidth weakly coupled grating effects, avoiding spectral overlap and crosstalk, and ensuring precise separation of multi-channel signals to meet the networking requirements of large-scale sensor networks in high-voltage power scenarios. (Reflection bandwidth) ;in, The center wavelength, The group refractive index.

[0037] Meanwhile, to explore the temperature sensing characteristics of the chip and simulate the real working environment of the photonic sensing chip, simulation analysis was conducted on a deeply etched ridge waveguide grating sensing chip at different temperatures, such as... Figure 7 The image shows the transmission spectrum of the photonic sensor chip from 25°C to 85°C. Its maximum reflectivity reaches 95% or higher, with a 3dB bandwidth of only about 0.25nm. This high reflectivity achieves an extremely narrow bandwidth for the sensor chip. As the temperature at the measurement point increases, the center wavelength of the sensor chip's reflection spectrum redshifts (drifts towards longer wavelengths). This is mainly due to the thermo-optical coefficient of silicon material (approximately 1.8 × 10⁻⁶). -4 ) and the coefficient of thermal expansion (approximately 2.6 × 10) -6 All values ​​are positive, and according to the Bragg condition, the wavelength shift is linearly related to the temperature change. The simulation results are fitted with the corresponding wavelength data at different temperatures, and the results are as follows: Figure 8 As shown, the temperature sensitivity of the photonic sensing chip of the present invention is approximately 72 pm / ℃.

[0038] Based on the above technical solution, the narrow-bandwidth photonic temperature sensing chip provided in this embodiment of the invention is integrated into the SOI platform, is compatible with mature CMOS technology, and has the advantages of small size, low cost, and strong anti-electromagnetic interference capability. It can be mass-produced, reducing system costs.

[0039] Implementation examples of large-scale parallel topology systems: Based on the same inventive concept, this embodiment also provides a large-scale parallel topology system. Figure 1This diagram illustrates a large-scale parallel topology system provided by an embodiment of the present invention. This large-scale parallel topology system is mainly used for temperature monitoring of power electronic equipment. Through precise matching of a narrow-bandwidth photonic temperature sensing chip with multiple sets of arrayed waveguide grating multiplexing technology, combined with a time-division-wavelength-division hybrid topology, it solves the bottlenecks of traditional temperature monitoring schemes, such as complex wiring, susceptibility to environmental interference, severe channel crosstalk, and the difficulty in large-scale networking caused by the excessively wide reflection bandwidth of traditional rectangular waveguide gratings.

[0040] like Figure 1 As shown, this large-scale parallel topology system includes a broadband light source, a circulator, an optical path gating module, a wavelength division multiplexing (WDM) module, a sensor network, and a signal demodulation module. The broadband light source is configured to provide a broadband optical signal. The optical path gating module is configured to perform time-division multiplexing gating on the broadband optical signal passing through the circulator and output it to one of the multiple optical path branches. The WDM module includes multiple sets of arrayed waveguide gratings, each set connected to one of the optical path branches, and is configured to distribute the input optical signal to multiple wavelength channels. The sensor network includes multiple narrow-bandwidth photonic temperature sensing chips as described in the narrow-bandwidth photonic temperature sensing chip embodiment. Each sensing chip is connected to a specific wavelength channel of the arrayed waveguide grating. Sensing chips connected to different wavelength channels of the same set of arrayed waveguide gratings are configured with different grating periods to match the corresponding channel center wavelength. The signal demodulation module is configured to receive the optical signal reflected by the sensing chips and analyze the wavelength shift of the received optical signal to determine the temperature change.

[0041] The aforementioned large-scale parallel topology system achieves time-division gating through an optical path gating module and wavelength-division multiplexing through multiple sets of arrayed waveguide gratings. This expands a single set of arrayed waveguide gratings into a low-crosstalk parallel sensing network with hundreds or more nodes. Even if one node fails, it does not affect the normal operation of other sensors, and sensor nodes can be dynamically reduced without reconfiguring the optical path. The entire system, centered on miniaturized photonic sensing chips and arrayed waveguide gratings, constructs a large-scale temperature monitoring network, particularly suitable for temperature monitoring of high-voltage power electronic equipment such as converter valves, IGBT modules, and transformers. This significantly reduces maintenance complexity and improves the safety, reliability, and intelligence level of power grid operation.

[0042] In a specific example, the system also includes a monitoring terminal, which is configured to control the timing of the optical path gating module, acquire wavelength data output by the signal demodulation module, and realize real-time temperature distribution display based on the optical path branches and wavelength data determined by the timing.

[0043] In a specific example, the signal demodulation module includes a spectral analysis unit, a photoelectric conversion unit, and a signal processing unit; the monitoring terminal includes a host computer and a display screen.

[0044] Specifically, the system controls the timing of the optical switches through a host computer, and synchronously analyzes the reflected signals through a spectral analysis unit, a photoelectric conversion unit, and a signal processing unit. Then, it displays the real-time temperature distribution on a screen. It is particularly suitable for temperature monitoring of high-voltage power electronic equipment such as converter valves, IGBT modules, and transformers. It is also suitable for other multi-node temperature monitoring scenarios such as industrial manufacturing and equipment thermal management.

[0045] In one specific example, the optical path gating module includes a MEMS-type optical switch configured for millisecond-level or sub-millisecond-level switching.

[0046] Specifically, this MEMS-type optical switch is a 1xM optical switch. Positioned between the circulator and each arrayed waveguide grating, it serves as the core of time-division multiplexing, enabling sequential distribution of broadband optical signals. Based on microelectromechanical systems (MEMS) micromirror array technology, this switch controls the deflection angle of the micromirrors via electrostatic drive, thereby switching the input broadband optical signal to any one of the M output ports. Key performance indicators of this MEMS-type optical switch include: switching response time in milliseconds (e.g., <10ms), insertion loss less than 1dB, and channel isolation >40dB.

[0047] The specific control logic of this MEMS optical switch is as follows: the host computer control module sends control commands according to a preset polling sequence, driving the MEMS optical switch to sequentially select the 1st to the Mth output ports. At any given time t, only one set of arrayed waveguide gratings (AWGs) (e.g., the kth set) and its connected multiple photonic temperature sensing chips are in operation, while other sets are in an optically disconnected state. At this time, the reflected light signal received by the demodulation module comes only from the currently selected kth set of sensor networks, thus effectively isolating signal interference between different arrayed waveguide grating (AWG) sets. Through this hybrid topology architecture combining time-division multiplexing (for M sets of arrayed waveguide gratings (AWGs)) and wavelength-division multiplexing (for multiple sensors within a single AWG), the system achieves independent addressing and parallel monitoring of multiple sensing nodes. Even in the event of node failure, the system still possesses stable parallel monitoring capabilities, and can dynamically reduce or remove sensor nodes without physical reconstruction, ultimately realizing the dynamic construction and flexible expansion of a large-scale parallel topology system.

[0048] As other implementation methods, the optical path selection module can also be a mechanical, thermo-optical, or silicon-based Mach-Zehnder type optical switch.

[0049] In one specific example, the channel spacing of the arrayed waveguide grating is set to a preset spacing value, which is configured to be greater than the maximum wavelength drift of the sensing chip within a preset operating temperature rise range, in order to isolate signal crosstalk between adjacent channels.

[0050] Specifically, each arrayed waveguide grating consists of an N-channel arrayed waveguide grating (AWG). When the MEMS optical switch is a 1xM optical switch, there are M sets of N-channel arrayed waveguide gratings (AWGs), enabling a large-scale temperature sensing network at the M×N node level. The channel spacing of this N-channel arrayed waveguide grating is set to a preset value of 2.4 nm, with a minimum insertion loss of approximately -3.55 dB per channel, a power non-uniformity of 0.78 dB between channels, and crosstalk suppression between adjacent channels better than -17 dB. This design highly matches the narrow bandwidth characteristics of the photonic sensing chip, ensuring accurate spectral separation.

[0051] Specifically, the arrayed waveguide grating (AWG) is a precision wavelength division multiplexing or demultiplexing device based on a silicon photonics integrated platform (SOI), used to decompose an input broadband optical signal (typically corresponding to the C-band 1520-1570nm) into multiple discrete wavelength channels. For example... Figure 9 As shown, the arrayed waveguide grating (AWG) includes an input waveguide 8, an input coupling unit 9, a phase modulation array waveguide 7, an output waveguide 10, and an output coupling unit 11. Figure 10 and Figure 11 These are enlarged views of the input and output modules of the arrayed waveguide grating (AWG), respectively. Figure 9 As shown, the working principle of this arrayed waveguide grating (AWG) is as follows: When a broadband optical signal is injected from the input waveguide 8, it is first uniformly decomposed into M sub-beams at the input coupling unit 9 and then enters the phase modulation array waveguide 7. The phase modulation array 7 consists of a set of waveguide arms with a precise optical path difference ΔL, which introduces a wavelength-dependent phase difference (Δφ=2πΔL / λ). When the optical signal is transmitted to the output coupling unit 11, the optical fields of different wavelengths undergo constructive interference at different spatial positions on the output plane due to the different cumulative phase differences, thus being guided to the predetermined output waveguide, achieving a one-to-one correspondence between wavelength and spatial position.

[0052] Based on the aforementioned design principle of arrayed waveguide gratings (AWG), in this embodiment of the invention, assuming the device center wavelength is 1550nm, the key device parameters optical path difference ΔL = 63.5μm, and the specific spatial layout of the input / output ports in the input / output coupling unit, the device performance was analyzed using electromagnetic simulation software. Figure 12The output channel response spectrum of the arrayed waveguide grating (AWG) is shown, with ports 1-8 corresponding to 8 channels. Simulation results show that the AWG can achieve precise 8-channel wavelength multiplexing / demultiplexing with a strictly uniform channel wavelength spacing of 2.4 nm. This characteristic stems from the wavelength-dependent phase delay of 2πΔL / λ in the device design and the precise diffraction positioning on the diffraction plane in the output coupling unit. Each wavelength channel forms an independent diffraction focus on the output plane and is precisely guided to the preset output port. In terms of performance indicators, the minimum insertion loss of a single channel is approximately -3.55 dB, mainly due to the transmission loss of the optical field in the phase modulation array region (scattering and bending loss from the silicon waveguide sidewalls) and the limitation of the coupling efficiency at the end face of the output coupling unit. The power non-uniformity between channels is only 0.78 dB, reflecting the precise control of the uniform distribution accuracy of the optical field in the input / output coupling unit and the optical path difference of the phase modulation waveguide. The crosstalk suppression between adjacent channels is better than -17 dB, demonstrating the effective isolation of the spatial focusing positions of different wavelengths on the output frequency focusing unit. The aforementioned key indicators were effectively verified through electromagnetic simulation software, fully demonstrating that the designed arrayed waveguide grating (AWG) meets the core requirements of the temperature monitoring system for high reliability and parallel multi-wavelength signal separation in terms of both structural implementation and performance indicators. In particular, the wavelength division multiplexing (WDM) channel design of this AWG is highly compatible with the narrowband reflection characteristics of the photonic sensing chip in the aforementioned embodiment. The sensing chip employs a deep etching process to form a strongly constrained single-mode ridge waveguide, whose Bragg reflection spectrum has a 3dB bandwidth of only 0.25 nm, far smaller than the channel bandwidth of the AWG. This ensures that the reflected wavelength signal of each sensing node falls completely within a single AWG demultiplexed channel without generating crosstalk between adjacent channels.

[0053] Based on the specific structure of the aforementioned large-scale parallel topology system, the system's working principle is as follows: The optical signal emitted by the broadband light source is sequentially selected by a circulator and a 1×M MEMS optical switch, resulting in M ​​groups of N-channel arrayed waveguide gratings. These are then uniformly distributed according to wavelength to N narrow-bandwidth photonic temperature sensing chips in the parallel architecture (each sensing chip corresponds to an independent wavelength channel). When an external temperature field acts on the grating region, the Bragg waveguide grating, composed of alternating distributions of two materials with different refractive indices, exhibits high reflectivity for wavelengths satisfying the Bragg condition, thus selectively reflecting specific wavelengths from the broadband light source. The optical signal satisfying the Bragg condition is reflected back along the original path, then bundled by the N-channel arrayed waveguide gratings (AWGs), output by the circulator to the spectral analysis, photoelectric conversion module, signal processing unit, and host computer. The host computer software synchronously parses the signals according to the optical switch sequence, mapping the same channel number (Ch1~Chn) to physical nodes of different AWG groups at different time periods (a total of M×N), ultimately displaying the network-wide temperature distribution, thermal imaging, or abnormal warnings on the screen in real time. This system uses a matching design that combines narrow-bandwidth photonic sensing chips with arrayed waveguide gratings, combined with time-division isolation of optical switches, to construct a large-scale parallel topology sensing network with low crosstalk and dynamic shaving capability.

[0054] Based on the above technical solutions, this invention, by designing a narrow-bandwidth photonic sensing chip and constructing a large-scale parallel topology system, can not only significantly improve the overall efficiency and reliability of temperature monitoring of power electronic equipment, but also help reduce wiring complexity and system cost, which is of great significance for promoting the advancement of smart grid monitoring technology.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A narrow-bandwidth photonic temperature sensing chip, characterized in that, The sensing chip includes a silicon-on-insulator (SiI) platform, on which a deeply etched ridge-type waveguide Bragg grating is disposed. The deeply etched ridge-type waveguide Bragg grating includes a ridge waveguide and planar waveguides located on both sides of the ridge waveguide. The ridge waveguide and the planar waveguide form a deeply etched structure for confining the optical field to the core region of the ridge waveguide. Grating modulation structures are provided at the two ends of the planar waveguides away from the ridge waveguide. The grating modulation structures include a plurality of grooves spaced apart and periodically distributed along the optical transmission direction parallel to the ridge waveguide. The grating modulation structures generate a weak coupling effect, making the 3dB bandwidth of the reflection spectrum of the sensing chip less than or equal to a set bandwidth threshold to maintain narrow bandwidth characteristics.

2. The narrow bandwidth photonic temperature sensing chip according to claim 1, characterized in that, The cross-sectional dimensions of the deeply etched ridge waveguide Bragg grating are configured as follows: total height of 220 nm, width of the ridge waveguide of 500 nm, height of the planar waveguide of 50 nm, and total width of the planar waveguide of 1000 nm.

3. A narrow-bandwidth photonic temperature sensing chip according to claim 1 or 2, characterized in that, The grating period, grating duty cycle of the grating modulation structure, and the etching depth of the deep etching structure are configured as adjustable parameters to adapt to different target operating wavelengths.

4. The narrow bandwidth photonic temperature sensing chip according to claim 3, characterized in that, The target operating band includes at least the O-band and the C-band. When the operation of the deeply etched ridge waveguide Bragg grating is extended to the C-band, the etching depth of the deeply etched structure is 170 nm, the modulation depth of the grating modulation structure is 60 nm, the grating period length of the grating modulation structure is 305.9 nm, the grating duty cycle of the grating modulation structure is 0.5, and the total number of grating periods of the grating modulation structure is 25000, so as to achieve a peak reflectivity higher than the set reflectivity threshold.

5. A narrow-bandwidth photonic temperature sensing chip according to any one of claims 1-4, characterized in that, The silicon-on-insulator platform comprises, from bottom to top, a bottom silicon substrate, a buried oxide layer, and a top silicon layer, with a silicon dioxide cladding covering the top silicon layer. The deeply etched ridge waveguide Bragg grating is formed in the top silicon layer. The bottom silicon substrate has a thickness of 725 μm and a width of 1 mm. The silicon dioxide cladding has a thickness of 2 μm and a refractive index of 1.4445. The top silicon layer is made of Si, has a thickness of 0.22 μm, and a refractive index of 3.4763.

6. A large-scale parallel topology system, characterized in that, The system includes a broadband light source, a circulator, an optical path gating module, a wavelength division multiplexing (WDM) module, a sensing network, and a signal demodulation module. The broadband light source is configured to provide a broadband optical signal. The optical path gating module is configured to perform time-division multiplexing gating on the broadband optical signal passing through the circulator and output it to one of the multiple optical path branches. The WDM module includes multiple sets of arrayed waveguide gratings, each set of arrayed waveguide gratings connected to one of the optical path branches, and is configured to distribute the input optical signal to multiple wavelength channels. The sensing network includes multiple narrow-bandwidth photonic temperature sensing chips as described in any one of claims 1-3, each sensing chip being connected to a specific wavelength channel of the arrayed waveguide gratings. Sensing chips connected to different wavelength channels of the same set of arrayed waveguide gratings are configured with different grating periods to match the corresponding channel center wavelength. The signal demodulation module is configured to receive the optical signal reflected by the sensing chips and analyze the wavelength shift of the received optical signal to determine the temperature change.

7. A large-scale parallel topology system according to claim 6, characterized in that, The channel spacing of the arrayed waveguide grating is set to a preset interval value, which is configured to be greater than the maximum wavelength drift of the sensing chip within a preset operating temperature rise range, so as to isolate signal crosstalk between adjacent channels.

8. A large-scale parallel topology system according to claim 6, characterized in that, The optical path selection module includes a MEMS optical switch configured for millisecond-level or sub-millisecond-level switching.

9. A large-scale parallel topology system according to claim 6, characterized in that, The system also includes a monitoring terminal, which is configured to control the timing of the optical path selection module, acquire wavelength data output by the signal demodulation module, and realize real-time temperature distribution display based on the optical path branches determined by the timing and the wavelength channels corresponding to the wavelength data.

10. A large-scale parallel topology system according to claim 9, characterized in that, The signal demodulation module includes a spectral analysis unit, a photoelectric conversion unit, and a signal processing unit; the monitoring terminal includes a host computer and a display screen.

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