Resonator and photonic chip

Abstract

The application provides a resonator and a photonic chip, comprising: a micro-ring waveguide and a straight waveguide, a coupling section of the straight waveguide and the micro-ring waveguide, in the coupling section, the straight waveguide and the micro-ring waveguide have the same waveguide structure, the waveguide structure comprises: a first waveguide arm and a second waveguide arm, and 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 and the second grating slots are one-to-one aligned. Thus, 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 a continuous outer boundary. Since the outer boundary is continuous, mode disturbance and sidewall scattering can be effectively suppressed, so that the scattering loss of the resonator can be significantly 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] A 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 a waveguide structure generally has a large waveguide transmission loss, resulting in a 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 a waveguide structure generally has a 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:

[0007] 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;

[0008] a plurality of first grating slots arranged along the extension direction of the radiation slot are arranged on the side of the first waveguide arm facing the radiation slot;

[0009] a plurality of second grating slots arranged along the extension direction of the radiation slot are arranged on the side of the second waveguide arm facing the radiation slot;

[0010] The first grating slots and the second grating slots are aligned one by one.

[0011] In the implementation process, the straight waveguide and the micro-ring waveguide have the same waveguide structure in the coupling section, and the waveguide structure comprises: a first waveguide arm and a second waveguide arm, and a radiation slot is arranged between the first waveguide arm and the second waveguide arm; a plurality of first grating slots are arranged on one side of the first waveguide arm facing the radiation slot and arranged along the extension direction of the radiation slot; a plurality of second grating slots are arranged on one side of the second waveguide arm facing the radiation slot and arranged along the extension direction of the radiation slot; and the first grating slots are aligned with the second grating slots one by one.

[0012] The second waveguide arm and the first waveguide arm in the waveguide structure of the coupling section can constitute an outer boundary continuous subwavelength grating slot waveguide. Because the outer boundary is continuous, mode disturbance and sidewall scattering can be effectively suppressed, so that the scattering loss of the resonator can be significantly reduced.

[0013] 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.

[0014] The waveguide structure of each mode transition section comprises:

[0015] a first waveguide arm and a second waveguide arm, and a radiation slot is arranged between the first waveguide arm and the second waveguide arm;

[0016] a plurality of first transition slots are arranged on one side of the first waveguide arm facing the radiation slot and arranged along the extension direction of the radiation slot; and a plurality of second transition slots are arranged on one side of the second waveguide arm facing the radiation slot and arranged along the extension direction of the radiation slot;

[0017] the first transition slots are aligned with the second transition slots one by one, the width of each first transition slot and the width of each second transition slot are inversely proportional to the distance from the transition slot 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.

[0018] In the implementation process, the waveguide structure of the mode transition section includes 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; the first waveguide arm and the second waveguide arm are respectively provided with a plurality of first transition slots and a plurality of second transition slots arranged in the light propagation direction on the side walls thereof facing the radiation slot, and the first transition slots and the second transition slots correspond to and align with each other. 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, so that the equivalent refractive index thereof realizes a smooth and continuous gradient change. Thus, through the gradually changing subwavelength equivalent medium environment, the mode reflection and scattering caused by the refractive index mutation are effectively suppressed, so that the optical propagation loss of the light wave in the transmission process can be significantly reduced.

[0019] Optionally, the size of each mode transition section in the extension direction of the radiation slot is greater than or equal to 20 times the subwavelength grating period.

[0020] The subwavelength grating period represents the sum of the size of the first grating slot in the extension direction of the radiation slot and the size of the first ridge in the extension direction of the radiation slot, and the first ridge represents a protruding structure between two adjacent first grating slots.

[0021] In the implementation process, by limiting the size of the mode transition section in the extension direction of the radiation slot to be greater than or equal to 20 times the subwavelength grating period, a sufficient number of grating periods can be provided to realize the gradual transition of the effective refractive index. Thus, the mode reflection, high-order mode excitation and scattering loss caused by the structure mutation are significantly suppressed, and the optical propagation loss of the light wave in the transmission process is significantly reduced.

[0022] Optionally, the straight waveguide further includes two guide sections, a first end of a first guide section is connected to a second end of a first mode transition section; and a first end of a second guide section is connected to a second end of a second mode transition section.

[0023] The waveguide structure of each guide section includes:

[0024] 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.

[0025] In the implementation process, the waveguide structure of the guide section includes 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. Thus, a slot-shaped waveguide structure can be formed. In combination with the mode transition section, the size of the transition slot in the mode transition section gradually changes in the light propagation direction, so that a smooth effective refractive index distribution can be formed in the waveguide, thereby significantly suppressing the reflection and scattering caused by the structure mutation, and effectively reducing the optical propagation loss of the light wave in the transmission process.

[0026] Optionally, the straight waveguide further comprises two strip waveguides; a first end of the first strip waveguide is located in the radiation slot of the first guiding section, and a first end of the second strip waveguide is located in the radiation slot of the second guiding section.

[0027] In the implementation process, by directly embedding the end of the strip waveguide into the radiation slot of the corresponding guiding section, efficient coupling of light waves from the low-loss strip waveguide to the slot waveguide structure can be achieved. This approach avoids mode mismatch and interface reflection caused by traditional end-face coupling or multi-stage cascading, thereby effectively reducing optical propagation loss of light waves in the input and output processes.

[0028] Optionally, the cross-sectional dimension of each strip waveguide gradually increases from the first end to the second end.

[0029] Correspondingly, for each guiding section, the width of the radiation slot of the guiding section gradually decreases from the side close to the first end of the corresponding strip waveguide to the side away from the strip waveguide, until it equals the width of the radiation slot of the coupling section.

[0030] In the implementation process, the strip waveguide usually supports a guided mode with high confinement and small mode field, while the mode field distribution of the slot waveguide is more diffuse, polarization-sensitive, and laterally expanded. If the strip waveguide is directly connected to a radiation slot with a fixed width, strong reflection and radiation loss will occur due to the sudden change in mode shape and effective refractive index.

[0031] By designing the width of the radiation slot of each guiding section to be wider from the side close to the first end of the corresponding strip waveguide to the side away from the strip waveguide, until it equals the width of the radiation slot of the coupling section.

[0032] In this way, the equivalent optical parameters of the waveguide can be continuously and smoothly transitioned, allowing the light field to gradually evolve when entering the slot waveguide from the strip waveguide, thereby effectively suppressing scattering, reflection, and energy leakage caused by structural discontinuity, and significantly improving the coupling efficiency and overall transmission performance of the light wave at the input / output port.

[0033] Optionally, the micro-ring waveguide comprises two straight regions and two curved regions.

[0034] The two straight regions are symmetric about the center of the micro-ring waveguide, and the two curved regions are symmetric about the center of the micro-ring waveguide.

[0035] In the implementation process, by setting the micro-ring waveguide to comprise two straight regions and two curved regions, and making the two straight regions symmetric about the center of the micro-ring waveguide and the two curved regions symmetric about the center of the micro-ring waveguide, the micro-ring waveguide can exhibit a runway shape, thereby significantly extending the coupling region of the micro-ring waveguide and the straight waveguide, and achieving higher coupling efficiency.

[0036] In a second aspect, the present application provides a photonic chip comprising the resonator described above. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0038] FIG. 1(a) is a structural schematic diagram of a prior art micro-ring resonator;

[0039] FIG. 1(b) is a structural schematic diagram of a prior art silicon strip waveguide;

[0040] FIG. 1(c) is a structural schematic diagram of a prior art slot waveguide;

[0041] FIG. 1(d) is a structural schematic diagram of a prior art sub-wavelength grating waveguide;

[0042] FIG. 1(e) is a structural schematic diagram of a prior art sub-wavelength grating slot waveguide;

[0043] Figure 2 FIG. 1(f) is a structural schematic diagram of a micro-ring resonator provided by the embodiments of the present application;

[0044] Figure 3 FIG. 1(g) is a structural schematic diagram of a waveguide structure of a region where a straight waveguide and a micro-ring waveguide are coupled, provided by the embodiments of the present application;

[0045] Figure 4 FIG. 1(h) is a structural schematic diagram of a resonator structure in FIG. 1(f) taken along the B-B line and obtained after amplification. Figure 2 FIG. 1(i) is a structural schematic diagram of the resonator structure in FIG. 1(h) taken along the B-B line and obtained after amplification. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0047] A microring resonator is an important integrated photonic device, and its basic structure is shown in FIG. 1(a) and is composed of a straight waveguide and a microring waveguide. The waveguide used in a photonic chip is generally a dielectric waveguide, and there is a certain intensity of evanescent field near the surface of the waveguide (usually a wavelength scale). When the spacing between two waveguides is within this scale, part of the light transmitted in one waveguide will be coupled into the other waveguide. Thus, the light input from the straight waveguide can be coupled into the microring waveguide. When the light coupled into the microring waveguide satisfies the resonance condition that the circumference of the microring is an integer multiple of the wavelength of the light, the light of the wavelength will have a resonance enhancement phenomenon, and accordingly the intensity of the light of the wavelength at the output end will be reduced. 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 important application value in many integrated optical fields, including on-chip optical filtering, hybrid integrated external cavity lasers, integrated optical sensing, optical frequency comb generation, and electro-optic / thermal-optic modulators.

[0048] The two most important performance indicators of a microring resonator are the quality factor and the free spectral range. The quality factor generally reflects the sharpness of the resonance peak. Generally, the higher the sharpness of the resonance peak, the higher the quality factor, which is mainly affected by the transmission loss of the microring waveguide and the coupling condition. The free spectral range describes the spacing between adjacent resonance peaks. Generally, the smaller the circumference of the microring, the larger the free spectral range.

[0049] In the fields of optical sensing and external cavity lasers, there is often a need for a microring resonator with a high quality factor and a large free spectral range, and the microring resonator needs to have sufficient spectral stability.

[0050] Current microring resonators are generally composed of silicon strip waveguides, as shown in FIG. 1(b). However, microring resonators composed of silicon strip waveguides are susceptible to thermal drift and nonlinear effects, which can cause the working point of the microring to drift.

[0051] To alleviate this problem, existing microring resonators are composed of slot waveguides, subwavelength grating waveguides, or subwavelength grating slot waveguides. A slot waveguide is shown in FIG. 1(c), a subwavelength grating waveguide is shown in FIG. 1(d), and a subwavelength grating slot waveguide is shown in FIG. 1(e).

[0052] However, when microring resonators are composed of existing waveguide structures, there is a trade-off between the quality factor and the free spectral range. Because increasing the free spectral range requires reducing the circumference of the microring, which means reducing the bending radius of the circular waveguide, this will lead to an increase in waveguide transmission loss, thereby reducing the quality factor.

[0053] To solve the problem that microring resonators composed of existing waveguide structures generally have large waveguide transmission loss in the related art, a resonator is provided in the embodiments of the present application. The resonator comprises:

[0054] Micro-ring waveguides and straight waveguides.

[0055] In one optional implementation of this application embodiment, the micro-ring waveguide may be a circular waveguide.

[0056] 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.

[0057] 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:

[0058] A first waveguide arm L1 and a second waveguide arm L2, with a radiation groove between them.

[0059] 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.

[0060] 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.

[0061] The first grating groove C1 and the second grating groove C2 are aligned one-to-one.

[0062] The dimension a1 of the first grating groove C1 along the direction of radiation is the same as the dimension a2 of the second grating groove C2 along the direction of radiation. The dimension b1 of the first grating groove C1 perpendicular to the direction of radiation is the same as the dimension b2 of the second grating groove C2 perpendicular to the direction of radiation. In other words, the shape and size of the first grating groove C1 are exactly the same as the shape and size of the second grating groove C2.

[0063] The structure protruding between two first grating grooves C1 is a first ridge G1, and the first ridge G1 and the first grating groove C1 are periodically arranged to form a subwavelength grating structure. Correspondingly, the structure protruding between two second grating grooves C2 is a second ridge G2, and the second ridge G2 and the second grating groove C2 are periodically arranged to also form a subwavelength grating structure. Similarly, the first ridge G1 and the second ridge G2 are completely identical in shape and size.

[0064] The total size z of the adjacent first grating groove C1 and the first ridge G1 along the extension direction of the radiation groove is also the subwavelength grating period. The subwavelength grating period can be designed according to the optical characteristics of the target light wave, so that the subwavelength grating period can be less than half of the wavelength of the target light wave in the medium, thereby suppressing high-order diffraction. For example, the target light wave can be a light wave with a wavelength of 1450nm-1650nm in vacuum. The actual wavelength of the light in the medium waveguide is about 700nm-800nm. Therefore, the total size of the adjacent first grating groove and the first ridge along the extension direction of the radiation groove can be in the range of 200nm to 350nm. For example, the total size of the adjacent first grating groove and the first ridge along the extension direction of the radiation groove can be 200nm, 300nm or 350nm. Since the subwavelength grating period is less than 200nm, it will cause a significant increase in waveguide loss, and greater than 350nm will cause multiple mode conduction of the waveguide, resulting in chaotic resonance spectrum. Therefore, the subwavelength grating period is limited to the range of 200nm to 350nm, thereby effectively suppressing the excitation of high-order modes while considering lower transmission loss, ensuring that the resonator has a clear, stable resonance spectrum and a high quality factor.

[0065] The subwavelength grating duty cycle f can be flexibly adjusted according to actual application needs. The subwavelength grating duty cycle f represents the proportion of the size a1 of the first grating groove C1 along the extension direction of the radiation groove to the entire subwavelength grating period z, and the duty cycle f satisfies: 0<f<1. The greater the duty cycle f, the greater the effective refractive index of the resonator.

[0066] The size x of the groove 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 size of the first grating groove perpendicular to the extension direction of the radiation groove.

[0067] For example, if the size of the first grating groove perpendicular to the extension direction of the radiation groove is 300nm, the value of x is in the range of 50nm to 150nm, and further, x can be 50nm, 100nm or 150nm. In this way, the appropriate width can be selected based on the size of the first grating groove perpendicular to the extension direction of the radiation groove and the process difficulty, thereby minimizing the scattering loss of the waveguide structure of the coupling section.

[0068] In the embodiments of the present application, if it is required to design the resonance peak of the resonator in 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 resonance peak position. For example, the duty cycle of the subwavelength grating can be 0.5.

[0069] The resonator provided by the embodiments of the present application has the same waveguide structure in the coupling section, the straight waveguide and the micro-ring waveguide, and the waveguide structure 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 grating slots arranged along the extension direction of the radiation slot are arranged on the side of the first waveguide arm facing the radiation slot; a plurality of second grating slots arranged along the extension direction of the radiation slot are arranged on the side of the second waveguide arm facing the radiation slot; and the first grating slots are aligned with the second grating slots one by one.

[0070] The second waveguide arm and the first waveguide arm in the waveguide structure 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, so that the scattering loss of the resonator can be significantly reduced.

[0071] In an optional implementation manner of the embodiments of the present application, in the straight waveguide, the waveguide structure outside the coupling section can be completely the same as the waveguide structure of the coupling section.

[0072] In another optional implementation manner of the embodiments of the present application, the straight waveguide can comprise two mode transition sections, the first end of the first mode transition section is connected with one end of the coupling section, and the first end of the second mode transition section is connected with the other end of the coupling section.

[0073] In combination with Figure 4 the drawings, Figure 4 is a schematic view of the resonator structure in Figure 2 , which specifically shows the schematic view of the transition from the strip waveguide structure to the waveguide structure of the coupling section.

[0074] The waveguide structure of each mode transition section can be as shown in Y1 of Figure 4 , and the waveguide structure of the mode transition section Y1 comprises:

[0075] a first waveguide arm L1 and a second waveguide arm L2, and a radiation slot is present between the first waveguide arm L1 and the second waveguide arm L2;

[0076] a plurality of first transition slots C3 arranged along the extension direction of the radiation slot are arranged on the side of the first waveguide arm L1 facing the radiation slot; and a plurality of second transition slots C4 arranged along the extension direction of the radiation slot are arranged on the side of the second waveguide arm L2 facing the radiation slot.

[0077] The first transition groove C3 and the second transition groove C4 are aligned one by one, and the width of each first transition groove C3 and the width of each second transition groove C4 are inversely proportional to the distance from itself to the coupling section. The width of the transition groove represents the size of the transition groove perpendicular to the extension direction of the radiation groove.

[0078] Since the width of each transition groove gradually increases in the direction towards the coupling section, the grating duty cycle of the waveguide part increases accordingly, so that the equivalent refractive index realizes a smooth and continuous gradient change. Thus, through the gradually changing sub-wavelength equivalent medium environment, the mode reflection and scattering caused by the refractive index mutation are effectively suppressed, so that the optical propagation loss of the light wave in the transmission process can be significantly reduced.

[0079] In the embodiments of the present application, the size of the mode transition section along the extension direction of the radiation groove can be set according to the sub-wavelength grating period. For example, the size of the mode transition section along the extension direction of the radiation groove can be greater than or equal to 20 times the sub-wavelength grating period. By limiting the size of the mode transition section along the extension direction of the radiation groove to be greater than or equal to 20 times the sub-wavelength grating period, a sufficient number of grating periods can be provided to realize the gradual transition of the effective refractive index. Thus, the mode reflection, high-order mode excitation and scattering loss caused by the structure mutation are significantly suppressed, and the optical propagation loss of the light wave in the transmission process is significantly reduced.

[0080] In an optional implementation manner of the embodiments of the present application, the straight waveguide can further include two guide sections.

[0081] In an optional implementation manner of the embodiments of the present application, the first end of the first guide section is connected with one end of the coupling section, and the first end of the second guide section is connected with the other end of the coupling section.

[0082] In another optional implementation manner of the embodiments of the present application, the first end of the first guide section is connected with the second end of the first mode transition section, and the first end of the second guide section is connected with the second end of the second mode transition section.

[0083] The waveguide structure of each guide section can include:

[0084] The first waveguide arm L1 and the second waveguide arm L2, and the radiation groove exists between the first waveguide arm L1 and the second waveguide arm L2.

[0085] Optionally, the straight waveguide can further include two strip waveguides; the first end of the first strip waveguide is located in the radiation groove of the first guide section, and the first end of the second strip waveguide is located in the radiation groove of the second guide section.

[0086] Similarly, in combination with the above description of the waveguide structure of the straight waveguide, the waveguide structure of the straight waveguide can be understood as follows: Figure 4As shown in the embodiments of the present application, the cross-sectional dimension of each bar waveguide Y3 can gradually increase from the first end to the second end; correspondingly, for each guide section, the width of the radiation slot of the guide section can gradually decrease from the side close to the first end of the corresponding bar waveguide to the side away from the bar waveguide, until equal to the width of the radiation slot of the coupling section.

[0087] In combination Figure 4 As shown, the guide section can include a first straight section Y2, a second straight section Y4, a third straight section Y5 and a fourth straight section Y6. The bar waveguide can include a tip section and a straight section;

[0088] The width of the radiation slot of the first straight section Y2 is equal to the width of the radiation slot of the coupling section.

[0089] The width of the radiation slot of the first straight section Y2 is equal to the width of the radiation slot of the coupling section. The width of the radiation slot of the second straight section Y4 gradually increases from the end close to the first straight section Y2 to the end away from the first straight section Y2, and the bar waveguide is not located in the radiation slot of the second straight section. The length of the third straight section Y5 is equal to the length of the tip section of the bar waveguide, and the tip section of the bar waveguide is located in the radiation slot of the third straight section. The projection of the fourth straight section Y6 in the direction perpendicular to the light propagation direction coincides with part of the straight section of the bar waveguide.

[0090] The length of the first straight section Y2 can be 0.5 microns. The length of the second straight section Y4 can be 0.12 microns. The length of the third straight section Y5 can be 3 microns. The length of the fourth straight section Y6 can be 0.5 microns. Under this size feature, the guide section and the bar waveguide cooperate to minimize light propagation loss.

[0091] Based on the same inventive concept, the embodiments of the present application provide a photonic chip, comprising the resonator described above.

[0092] In this document, the terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0093] In this document, plural means two or more.

[0094] The above only describes the embodiments of the present application and is not used to limit the protection scope of the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A resonator characterized by, 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 one by one; 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.

2. The resonator of claim 1, wherein 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.

3. The resonator of claim 1, wherein 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.

4. The resonator of claim 3, wherein 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.

5. The resonator of claim 4, wherein, 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.

6. The resonator of claim 1, wherein 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.

7. A photonic chip, characterized in that Including the resonator as described in any one of claims 1 to 6.

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