Resonator and photon chip

Abstract

The invention provides a resonator and a photon chip, and the resonator comprises a micro-ring waveguide and a straight waveguide, the coupling region of the straight waveguide and the micro-ring waveguide is a coupling section, the straight waveguide and the micro-ring waveguide have the same waveguide structure at the coupling section, and the waveguide structure comprises a first waveguide arm and a second waveguide arm, a radiation groove is formed between the first waveguide arm and the second waveguide arm; a plurality of first grating grooves arranged along the extension direction of the radiation groove are formed in one side, facing the radiation groove, of the first waveguide arm; a plurality of second grating grooves arranged along the extension direction of the radiation groove are formed in one side, facing the radiation groove, of the second waveguide arm; and the first grating grooves are aligned with the second grating grooves one by one. The second waveguide arm and the first waveguide arm in the waveguide structure of the coupling section can form a sub-wavelength grating groove-shaped waveguide with a continuous outer boundary. Due to the fact that the outer boundary is continuous, mode disturbance and side wall scattering can be effectively restrained, and scattering loss of the resonator can be remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optics, in particular to a resonator and a photonic chip. BACKGROUND

[0002] Micro-ring resonator is an important integrated photonic device, and its basic structure is shown in Fig. 1(a), which is composed of a straight waveguide and a micro-ring waveguide.

[0003] The current micro-ring resonator is usually composed of a silicon strip waveguide, a slot waveguide, a sub-wavelength grating waveguide or a sub-wavelength grating slot waveguide. The silicon strip waveguide is shown in Fig. 1(b). The slot waveguide is shown in Fig. 1(c), the sub-wavelength grating waveguide is shown in Fig. 1(d), and the sub-wavelength grating slot waveguide is shown in Fig. 1(e).

[0004] However, the current micro-ring resonator composed of waveguide structure generally has large waveguide transmission loss, resulting in low quality factor. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide a resonator and a photonic chip to solve the problem that the current micro-ring resonator composed of waveguide structure generally has large waveguide transmission loss.

[0006] The embodiments of the present application provide a resonator, which comprises a micro-ring waveguide and a straight waveguide, a region where the straight waveguide and the micro-ring waveguide are coupled is a coupling section, in the coupling section, the straight waveguide and the micro-ring waveguide have the same waveguide structure, and the waveguide structure comprises: a first waveguide arm and a second waveguide arm, there is a radiation slot between the first waveguide arm and the second waveguide arm; a side of the first waveguide arm facing the radiation slot is provided with a plurality of first grating slots arranged along the extension direction of the radiation slot; a side of the second waveguide arm facing the radiation slot is provided with a plurality of second grating slots arranged along the extension direction of the radiation slot; the first grating slots are aligned with the second grating slots one by one.

[0007] In the above implementation process, in the coupling section, the straight waveguide and the micro-ring waveguide have the same waveguide structure, and the waveguide structure comprises: a first waveguide arm and a second waveguide arm, there is a radiation slot between the first waveguide arm and the second waveguide arm; a side of the first waveguide arm facing the radiation slot is provided with a plurality of first grating slots arranged along the extension direction of the radiation slot; a side of the second waveguide arm facing the radiation slot is provided with a plurality of second grating slots arranged along the extension direction of the radiation slot; and the first grating slots are aligned with the second grating slots one by one.

[0008] The second waveguide arm and the first waveguide arm in the waveguide structure of the coupling section can constitute a subwavelength grating slot waveguide with continuous outer boundary. Since the outer boundary is continuous, mode disturbance and sidewall scattering can be effectively suppressed, thereby significantly reducing scattering loss of the resonator.

[0009] Optionally, the straight waveguide further comprises two mode transition sections, a first end of a first mode transition section is connected with one end of the coupling section, and a first end of a second mode transition section is connected with the other end of the coupling section. The waveguide structure of each mode transition section comprises: a first waveguide arm and a second waveguide arm, and a radiation slot is present between the first waveguide arm and the second waveguide arm; a plurality of first transition slots arranged along the extension direction of the radiation slot are arranged on the side of the first waveguide arm facing the radiation slot; and a plurality of second transition slots arranged along the extension direction of the radiation slot are arranged on the side of the second waveguide arm facing the radiation slot; The first transition slots and the second transition slots are one-to-one aligned, the width of each first transition slot and the width of each second transition slot are inversely proportional to the distance from itself to the coupling section, and the width of the transition slot represents the size of the transition slot perpendicular to the extension direction of the radiation slot.

[0010] In the implementation process, the waveguide structure of the mode transition section comprises a first waveguide arm and a second waveguide arm, and a radiation slot is present between the first waveguide arm and the second waveguide arm; a plurality of first transition slots and a plurality of second transition slots arranged along the light propagation direction are arranged on the side wall of the first waveguide arm and the second waveguide arm facing the radiation slot, respectively, and the first transition slots and the second transition slots are one-to-one corresponding and aligned. Since the width of each transition slot gradually increases in the direction towards the coupling section, the grating duty cycle of the waveguide locally increases, thereby enabling the equivalent refractive index to achieve a smooth and continuous gradient change. Through the gradually changing subwavelength equivalent medium environment, mode reflection and scattering caused by refractive index discontinuity are effectively suppressed, thereby significantly reducing the optical propagation loss of light waves in the transmission process.

[0011] Optionally, the size of each mode transition section along the extension direction of the radiation slot is greater than or equal to 20 times the subwavelength grating period. The subwavelength grating period represents the sum of the size of the first grating slot along the extension direction of the radiation slot and the size of the first ridge along the extension direction of the radiation slot, and the first ridge represents a protruding structure between two adjacent first grating slots.

[0012] In the above implementation process, by limiting the size of the mode transition section along the direction of the radiating groove to be greater than or equal to 20 times the subwavelength grating period, a sufficient number of grating periods can be provided to achieve a gradual transition of the effective refractive index. This significantly suppresses mode reflection, higher-order mode excitation, and scattering loss caused by structural abrupt changes, thereby significantly reducing the optical propagation loss of light waves during transmission.

[0013] Optionally, the straight waveguide further includes two guiding sections, with a first end of the first guiding section connected to a second end of the first mode transition section; and a first end of the second guiding section connected to a second end of the second mode transition section. The waveguide structure of each of the aforementioned guiding segments includes: A first waveguide arm and a second waveguide arm, with a radiation groove between the first waveguide arm and the second waveguide arm. In the above implementation process, the waveguide structure of the guiding section includes a first waveguide arm and a second waveguide arm, and a radiation slot exists between the first and second waveguide arms. This constitutes a slotted waveguide structure. Furthermore, combined with a mode transition section, the size of the transition slot in the mode transition section gradually changes along the light propagation direction, thus forming a smooth effective refractive index distribution in the waveguide. This significantly suppresses reflection and scattering caused by structural abrupt changes, thereby effectively reducing the optical propagation loss of light waves during transmission.

[0014] Optionally, the straight waveguide further includes two strip waveguides; the first end of the first strip waveguide is located in the radiation slot of the first guide section, and the first end of the second strip waveguide is located in the radiation slot of the second guide section.

[0015] In the above implementation process, by directly embedding the end of the strip waveguide into the radiation slot of the corresponding guiding segment, efficient coupling of light waves from the low-loss strip waveguide to the slot waveguide structure can be achieved. This method avoids mode mismatch and interface reflection caused by traditional end-face coupling or multi-segment cascading, thereby effectively reducing the optical propagation loss of light waves during input and output.

[0016] Optionally, the cross-sectional dimensions of each strip waveguide gradually increase from the first end to the second end; Correspondingly, for each guide segment, the width of the radiation slot of the guide segment gradually decreases from the side closer to the first end of the corresponding strip waveguide to the side farther away from the strip waveguide, until it is equal to the width of the radiation slot of the coupling segment.

[0017] In the above implementation process, strip waveguides typically support highly confined, small-mode-field guided modes, while slot waveguides have a more diffuse mode field distribution, are more polarization-sensitive, and have a larger lateral extension. If a strip waveguide is directly connected to a radiation slot of fixed width, the abrupt change in mode field shape and effective refractive index will lead to strong reflection and radiation loss.

[0018] The width of the radiation slot of each guiding segment is designed to be wider starting from the side closest to the first end of the corresponding strip waveguide and gradually decreasing towards the side away from the strip waveguide until it is equal to the width of the radiation slot of the coupling segment.

[0019] This allows for a continuous and smooth transition of the waveguide's equivalent optical parameters, enabling the optical field to evolve gradually as it moves from the strip waveguide into the slot waveguide. This effectively suppresses scattering, reflection, and energy leakage caused by structural abrupt changes, significantly improving the coupling efficiency and overall transmission performance of the light wave at the input / output ports.

[0020] Optionally, the microring waveguide includes two straight regions and two curved regions; The two straight regions are symmetrical about the center of the microring waveguide, and the two curved regions are symmetrical about the center of the microring waveguide.

[0021] In the above implementation, the micro-ring waveguide is configured to include two straight regions and two curved regions, with the two straight regions and the two curved regions being symmetrical about the center of the micro-ring waveguide. This allows the micro-ring waveguide to adopt a racetrack shape, thereby significantly extending the coupling region between the micro-ring waveguide and the straight waveguide, and ultimately achieving higher coupling efficiency.

[0022] Secondly, this application provides a photonic chip, including the resonator described above. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1(a) is a schematic diagram of the structure of an existing microring resonator; Figure 1(b) is a schematic diagram of the structure of an existing silicon strip waveguide; Figure 1(c) is a schematic diagram of the existing slot waveguide structure; Figure 1(d) is a schematic diagram of the structure of an existing subwavelength grating waveguide; Figure 1(e) is a schematic diagram of the structure of an existing subwavelength grating groove waveguide; Figure 2 This is a schematic diagram of the structure of a microring resonator provided in an embodiment of this application; Figure 3 A schematic diagram of a waveguide structure in a region where a straight waveguide and a micro-ring waveguide are coupled, provided in an embodiment of this application; Figure 4 The embodiments provided in this application provide for the Figure 2 The schematic diagram of the resonator structure is obtained by cutting along the BB line and enlarging it. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0026] The microring resonator is an important integrated photonic device. Its basic structure, as shown in Figure 1(a), consists of a straight waveguide and a microring waveguide. The waveguides used in photonic chips are generally dielectric waveguides. A certain intensity of evanescent field is distributed near the waveguide surface (typically on the wavelength scale). When the spacing between two waveguides is within this scale, a portion of the light transmitted in one waveguide will couple into the other. Thus, light input from the straight waveguide can couple into the microring waveguide. When the coupled light satisfies the resonance condition that the microring perimeter is an integer multiple of the light wavelength, the light of that wavelength will experience resonance enhancement, and correspondingly, the intensity of that wavelength at the output will decrease. Therefore, when broadband input light passes through the microring resonator, a series of periodic resonance peaks can be observed in the spectrum of the output light. This has significant application value in many fields of integrated optics, including on-chip optical filtering, hybrid integrated external cavity lasers, integrated optical sensing, optical frequency comb generation, and electro-optic / thermo-optic modulators.

[0027] The two most important performance indicators of a microring resonator are the quality factor and the free spectral range. The quality factor usually reflects the sharpness of the resonant peak; generally, the higher the sharpness of the resonant peak, the higher the quality factor. This is mainly affected by the transmission loss and coupling conditions of the microring waveguide. The free spectral range describes the spacing between adjacent resonant peaks; generally, the smaller the circumference of the microring, the larger the free spectral range.

[0028] In fields such as optical sensing and external cavity lasers, microring resonators typically require high quality factor and a large free spectral range, as well as sufficient spectral stability.

[0029] Current microring resonators are typically constructed from silicon strip waveguides, as shown in Figure 1(b). However, microring resonators constructed from silicon strip waveguides are susceptible to thermal drift and nonlinear effects, which can cause the microring operating point to drift.

[0030] To alleviate this problem, existing methods utilize slot waveguides, subwavelength grating waveguides, or subwavelength grating slot waveguides to construct micro-ring resonators. A slot waveguide is shown in Figure 1(c), a subwavelength grating waveguide in Figure 1(d), and a subwavelength grating slot waveguide in Figure 1(e).

[0031] However, existing waveguide structures used to construct microring resonators all face a trade-off between quality factor and free spectral range. This is because increasing the free spectral range requires reducing the perimeter of the microring, which means reducing the bending radius of the circular waveguide. This leads to increased waveguide transmission loss, thereby reducing the quality factor.

[0032] To address the problem of significant waveguide transmission loss in existing waveguide-structured microring resonators, this application provides a resonator comprising: Micro-ring waveguides and straight waveguides.

[0033] In one optional implementation of this application embodiment, the micro-ring waveguide may be a circular waveguide.

[0034] In another optional implementation of the embodiments of this application, see [link to relevant documentation]. Figure 2 As shown, Figure 2 This is a schematic diagram of a resonator structure provided in an embodiment of this application. The microring waveguide may include two straight regions and two curved regions; the two straight regions are centrally symmetrical about the microring waveguide, and the two curved regions are also centrally symmetrical about the microring waveguide. Furthermore, the straight waveguide can be coupled to one of the straight regions of the microring waveguide. Thus, compared to using a circular waveguide as the microring waveguide, the coupling region between the straight waveguide and the microring waveguide can be significantly extended, thereby significantly improving the coupling efficiency between the straight waveguide and the microring waveguide.

[0035] Optionally, combined Figure 3 As shown, Figure 3 Yes Figure 2 The schematic diagram of the resonator structure is obtained by cropping and enlarging along line AA, specifically showing the waveguide structure in the region where the straight waveguide and the micro-ring waveguide are coupled. The coupling section is the region where the straight waveguide and the micro-ring waveguide are coupled. In the coupling section, the straight waveguide and the micro-ring waveguide have the same waveguide structure, which includes: A first waveguide arm L1 and a second waveguide arm L2, with a radiation groove between them.

[0036] The first waveguide arm L1 has multiple first grating slots C1 arranged along the extension direction of the radiation slot on the side facing the radiation slot. The second waveguide arm L2 has multiple second grating slots C2 arranged along the extension direction of the radiation slot on the side facing the radiation slot. The first grating groove C1 and the second grating groove C2 are aligned one-to-one.

[0037] The dimension a1 of the first grating groove C1 along the extending direction of the radiation groove is the same as the dimension a2 of the second grating groove C2 along the extending direction of the radiation groove, and the dimension b1 of the first grating groove C1 perpendicular to the extending direction of the radiation groove is the same as the dimension b2 of the second grating groove C2 perpendicular to the extending direction of the radiation groove. In other words, the shape and size of the first grating groove C1 are exactly the same as those of the second grating groove C2.

[0038] The protruding structure between two first grating grooves C1 is the first ridge G1. The first ridge G1 and the first grating groove C1 are arranged periodically, forming a sub-wavelength grating structure. Correspondingly, the protruding structure between two second grating grooves C2 is the second ridge G2. The second ridge G2 and the second grating groove C2 are arranged periodically, also forming a sub-wavelength grating structure. Similarly, the shape and size of the first ridge G1 and the second ridge G2 are exactly the same.

[0039] The total dimension z of an adjacent first grating groove C1 and the first ridge G1 along the extending direction of the radiation groove is the sub-wavelength grating period. The sub-wavelength grating period can be designed according to the optical characteristics of the target light wave, so that the sub-wavelength grating period is less than half of the wavelength of the target light wave in the medium, thereby suppressing higher-order diffraction. Exemplarily, the target light wave can be a light wave with a wavelength of 1450 nm - 1650 nm in vacuum. The actual wavelength of the light in this band during transmission in the dielectric waveguide is about 700 nm - 800 nm. Therefore, the total dimension of an adjacent first grating groove and the first ridge along the extending direction of the radiation groove can be within the range of 200 nm to 350 nm. Exemplarily, the total dimension of an adjacent first grating groove and the first ridge along the extending direction of the radiation groove can be 200 nm, 300 nm or 350 nm. Since the waveguide loss will increase significantly when the sub-wavelength grating period is less than 200 nm, and multi-mode conduction of the waveguide will occur when it is greater than 350 nm, resulting in a chaotic resonance spectrum. Therefore, the sub-wavelength grating period is limited within the range of 200 nm to 350 nm, so as to effectively suppress the excitation of higher-order modes while taking into account lower transmission losses, ensuring that the resonator has a clear, stable resonance spectrum and a high quality factor.

[0040] The duty cycle f of the sub-wavelength grating can be flexibly adjusted according to actual application needs. The duty cycle f of the sub-wavelength grating characterizes the proportion of the dimension a1 of the first grating groove C1 along the extending direction of the radiation groove in the entire sub-wavelength grating period z, and the duty cycle f satisfies: 0 < f < 1. The larger the duty cycle f, the larger the effective refractive index of the resonator.

[0041] The dimension x from the bottom of the first grating groove to the side of the first waveguide arm away from the radiation groove can be determined according to the dimension of the first grating groove perpendicular to the extending direction of the radiation groove.

[0042] For example, if the dimension of the first grating groove perpendicular to the extension direction of the radiation groove is 300 nm, the corresponding value of x is in the range of 50 nm to 150 nm. Furthermore, x can be 50 nm, 100 nm, or 150 nm. In this way, a suitable width can be selected based on a comprehensive consideration of the dimension of the first grating groove perpendicular to the extension direction of the radiation groove and the manufacturing difficulty, thereby minimizing the scattering loss of the waveguide structure in the coupling section.

[0043] In this embodiment, if it is necessary to design the resonant peak of the resonator within a specific wavelength range, the effective refractive index of the entire resonator can be controlled by adjusting the duty cycle to achieve the design of the resonant peak position. For example, the duty cycle of the subwavelength grating can be 0.5.

[0044] The resonator provided in this application embodiment has the same waveguide structure in the coupling section, where the straight waveguide and the micro-ring waveguide have the same waveguide structure, and the waveguide structure includes: a first waveguide arm and a second waveguide arm, with a radiation slot between the first waveguide arm and the second waveguide arm; a plurality of first grating slots are provided on the side of the first waveguide arm facing the radiation slot, arranged along the extension direction of the radiation slot; a plurality of second grating slots are provided on the side of the second waveguide arm facing the radiation slot, arranged along the extension direction of the radiation slot; the first grating slots and the second grating slots are aligned one by one.

[0045] In this waveguide structure, the second and first waveguide arms can form a subwavelength grating slot waveguide with a continuous outer boundary. Due to the continuous outer boundary, mode disturbances and sidewall scattering can be effectively suppressed, thereby significantly reducing the scattering loss of the resonator.

[0046] In one optional implementation of this application, in a straight waveguide, the waveguide structure outside the coupling section can be exactly the same as the waveguide structure of the coupling section.

[0047] In another optional implementation of the embodiments of this application, the straight waveguide may include two mode transition sections, the first end of the first mode transition section is connected to one end of the coupling section, and the first end of the second mode transition section is connected to the other end of the coupling section; Combination Figure 4 As shown, Figure 4 Yes Figure 2 The schematic diagram of the resonator structure is obtained by cutting and enlarging along the BB line, which specifically shows the schematic diagram of the waveguide structure transitioning from the strip waveguide structure to the coupling section.

[0048] The waveguide structure of each mode transition section can be as follows: Figure 4 As shown in Y1, the waveguide structure of the mode transition section Y1 includes: A first waveguide arm L1 and a second waveguide arm L2, with a radiation groove between the first waveguide arm L1 and the second waveguide arm L2; The first waveguide arm L1 has multiple first transition grooves C3 arranged along the extension direction of the radiation groove on the side facing the radiation groove; the second waveguide arm L2 has multiple second transition grooves C4 arranged along the extension direction of the radiation groove on the side facing the radiation groove. The first transition groove C3 and the second transition groove C4 are aligned one to one. The width of each first transition groove C3 and the width of each second transition groove C4 are inversely proportional to their distance from the coupling section. The width of the transition groove represents the dimension of the transition groove perpendicular to the extension direction of the radiation groove.

[0049] As the width of each transition groove gradually increases towards the coupling section, the local grating duty cycle of the waveguide increases accordingly, resulting in a smooth and continuous gradient change in its equivalent refractive index. This gradually changing subwavelength equivalent medium environment effectively suppresses mode reflection and scattering caused by abrupt changes in refractive index, thereby significantly reducing optical propagation loss during light transmission.

[0050] In this embodiment, the dimension of the mode transition section extending along the radiating groove can be set according to the subwavelength grating period. For example, the dimension of the mode transition section extending along the radiating groove can be greater than or equal to 20 times the subwavelength grating period. By limiting the dimension of the mode transition section extending along the radiating groove to be greater than or equal to 20 times the subwavelength grating period, a sufficient number of grating periods can be provided to achieve a gradual transition of the effective refractive index. This significantly suppresses mode reflection, higher-order mode excitation, and scattering loss caused by structural abrupt changes, thereby significantly reducing the optical propagation loss of light waves during transmission.

[0051] In one optional implementation of the embodiments of this application, the straight waveguide may optionally include two guiding segments.

[0052] In one optional implementation of this application, the first end of the first guide segment is connected to one end of the coupling segment, and the first end of the second guide segment is connected to the second end of the coupling segment.

[0053] In another optional implementation of this application embodiment, the first end of the first guide segment is connected to the second end of the first mode transition segment; the first end of the second guide segment is connected to the second end of the second mode transition segment.

[0054] The waveguide structure of each guiding segment may include: A first waveguide arm L1 and a second waveguide arm L2, with a radiation groove between them. Optionally, the straight waveguide may also include two strip waveguides; the first end of the first strip waveguide is located in the radiation slot of the first guide segment, and the first end of the second strip waveguide is located in the radiation slot of the second guide segment.

[0055] Similarly, combined Figure 4 As shown in the embodiments of this application, the cross-sectional dimensions of each strip waveguide Y3 can gradually increase from the first end to the second end; correspondingly, for each guiding segment, the width of the radiation slot of the guiding segment can gradually decrease from the side close to the first end of the corresponding strip waveguide to the side away from the strip waveguide, until it is equal to the width of the radiation slot of the coupling segment.

[0056] Combination Figure 4 As shown, the guiding segment may include a first straight segment Y2, a second straight segment Y4, a third straight segment Y5, and a fourth straight segment Y6. The strip waveguide may include a tip segment and a straight section; The width of the radiating slot in the first straight line segment Y2 is equal to the width of the radiating slot in the coupling segment.

[0057] The width of the radiating slot in the first straight segment Y2 is equal to the width of the radiating slot in the coupling segment. The width of the radiating slot in the second straight segment Y4 gradually increases from the end closer to the first straight segment Y2 to the end farther away from the first straight segment Y2, and the strip waveguide is not located within the radiating slot of the second straight segment. The length of the third straight segment Y5 is equal to the length of the tip segment of the strip waveguide, and the tip segment of the strip waveguide is located within the radiating slot of the third straight segment. The projection of the fourth straight segment Y6 perpendicular to the direction of light propagation coincides with a portion of the straight section of the strip waveguide.

[0058] The length of the first straight segment Y2 can be 0.5 micrometers. The length of the second straight segment Y4 can be 0.12 micrometers. The length of the third straight segment Y5 can be 3 micrometers. The length of the fourth straight segment Y6 can be 0.5 micrometers. Under these dimensional characteristics, the guiding segment and the strip waveguide can be matched to minimize optical propagation loss.

[0059] Based on the same inventive concept, this application provides a photonic chip including the resonator described above.

[0060] In this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying any such actual relationship or order between these entities or operations.

[0061] In this article, "multiple" refers to two or more.

[0062] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A resonator, characterized in that, include: The waveguide includes a microring waveguide and a straight waveguide. The region where the straight waveguide couples with the microring waveguide is called a coupling section. In the coupling section, the straight waveguide and the microring waveguide have the same waveguide structure, which includes: A first waveguide arm and a second waveguide arm, with a radiation groove between the first waveguide arm and the second waveguide arm; The first waveguide arm has a plurality of first grating slots arranged along the extension direction of the radiation slot on the side facing the radiation slot. The second waveguide arm has a plurality of second grating slots arranged along the extension direction of the radiation slot on the side facing the radiation slot. The first grating groove is aligned with the second grating groove.

2. The resonator according to claim 1, characterized in that, The straight waveguide also includes two mode transition sections, with the first end of the first mode transition section connected to one end of the coupling section, and the first end of the second mode transition section connected to the other end of the coupling section. The waveguide structure in each of the aforementioned mode transition segments includes: A first waveguide arm and a second waveguide arm, with a radiation groove between the first waveguide arm and the second waveguide arm; The first waveguide arm has a plurality of first transition grooves arranged along the extension direction of the radiation groove on the side facing the radiation groove; the second waveguide arm has a plurality of second transition grooves arranged along the extension direction of the radiation groove on the side facing the radiation groove. The first transition groove and the second transition groove are aligned one by one. The width of each first transition groove and the width of each second transition groove are inversely proportional to the distance from themselves to the coupling section. The width of the transition groove represents the dimension of the transition groove perpendicular to the extension direction of the radiation groove.

3. The resonator according to claim 2, characterized in that, The dimension of each mode transition section along the direction of radiation groove is greater than or equal to 20 times the subwavelength grating period; The subwavelength grating period represents the sum of the dimensions of the first grating slot along the direction of the radiating slot and the dimensions of the first ridge along the direction of the radiating slot. The first ridge represents a protruding structure located between two adjacent first grating slots.

4. The resonator according to claim 2, characterized in that, The straight waveguide also includes two guide sections, with the first end of the first guide section connected to the second end of the first mode transition section; and the first end of the second guide section connected to the second end of the second mode transition section. The waveguide structure of each of the aforementioned guiding segments includes: A first waveguide arm and a second waveguide arm, with a radiation groove between the first waveguide arm and the second waveguide arm.

5. The resonator according to claim 4, characterized in that, The straight waveguide also includes two strip waveguides; the first end of the first strip waveguide is located in the radiation slot of the first guide section, and the first end of the second strip waveguide is located in the radiation slot of the second guide section.

6. The resonator according to claim 5, characterized in that, The cross-sectional dimensions of each strip waveguide gradually increase from the first end to the second end; Correspondingly, for each guide segment, the width of the radiation slot of the guide segment gradually decreases from the side closer to the first end of the corresponding strip waveguide to the side farther away from the strip waveguide, until it is equal to the width of the radiation slot of the coupling segment.

7. The resonator according to claim 1, characterized in that, The microring waveguide includes two straight regions and two curved regions; The two straight regions are symmetrical about the center of the microring waveguide, and the two curved regions are symmetrical about the center of the microring waveguide.

8. A photonic chip, characterized in that, Including the resonator as described in any one of claims 1 to 7.

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