Microring resonators and optical devices

Abstract

The present invention provides a micro-ring resonant cavity and an optical device, comprising: an input waveguide, a first coupling region, a micro-ring structure, a second coupling region, and an output waveguide; the input waveguide and the output waveguide are respectively provided with a first polarization rotator and a second polarization rotator, and the first polarization rotator and the second polarization rotator are both provided with a trapezoidal cut angle structure; the input waveguide and the output waveguide are arranged in parallel, and the micro-ring structure is arranged between the input waveguide and the output waveguide; when the light of the first mode is transmitted to the first polarization rotator or the second polarization rotator, the first polarization rotator or the second polarization rotator is used to rotate the polarization of the light of the first mode and output the light of the second mode; wherein, when the first mode is a TE or TM mode, the second mode is a TM or TE mode. The light of the first mode is converted into the second mode by the trapezoidal cut angle structure, and the coupling of the micro-ring resonant cavity is enhanced by using the stronger coupling ability of the TM mode without changing the performance parameters of the micro-ring structure.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to a micro-ring resonant cavity and an optical device. Background Art

[0002] As a highly integrated and highly sensitive optical device, the microring resonator has broad application prospects and can be used in optical communications, biosensors, quantum information processing and other fields. The microring is composed of a section of optical waveguide to form a ring structure. When the optical signal propagates in the ring waveguide, multiple reflections and interferences will occur, thus forming a resonance phenomenon. The optical signal must be coupled to enter the microring. The typical coupling of the microring resonator is point-line short-distance coupling. The commonly used optical transmission signal is the TE mode (transverse electric wave mode), which has weak coupling. In flat-top filters and large-scale multi-coupled integrated systems, relatively strong coupling is often required, which limits the application of microring resonators.

[0003] At present, the commonly used methods to enhance coupling include reducing the interval between the microring and the input and output waveguides, and using a racetrack or curved coupling structure in the coupling area to increase the coupling length. Reducing the interval requires relatively high precision in the processing technology; the racetrack coupling area structure will affect the structure and performance parameters of the original microring. For example, in an optical communication system, the addition of a racetrack structure will increase the cavity length of the resonant cavity, reduce the free spectral range of the microring resonant cavity, and reduce the channel capacity; in the curved coupling area, the optical signal needs to meet the phase matching conditions for coupling to occur, and the additional curved waveguide will increase more bending losses, and the design is also more complicated.

[0004] Therefore, enhancing the coupling ability between the microring structure and the input and output waveguides without changing the performance parameters of the microring structure is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a microring resonator and an optical device, which can destroy the waveguide symmetry by a trapezoidal cut-angle structure to convert the TE mode into the TM mode, and enhance the coupling of the microring resonator by utilizing the stronger coupling ability of the TM without changing the performance parameters of the microring structure.

[0006] In a first aspect, an embodiment of the present invention provides a microring resonant cavity, which includes: an input waveguide, a first coupling region, a microring structure, a second coupling region, and an output waveguide; the input waveguide is provided with a first polarization rotator, the output waveguide is provided with a second polarization rotator, and the first polarization rotator and the second polarization rotator are both provided with a trapezoidal cut-angle structure; the input waveguide and the output waveguide are arranged in parallel, and the microring structure is arranged between the input waveguide and the output waveguide; when light of a first mode is transmitted to the first polarization rotator or the second polarization rotator, the first polarization rotator or the second polarization rotator is used to rotate the polarization of the light of the first mode and output light of the second mode; wherein, when the first mode is a TE mode, the second mode is a TM mode; when the first mode is a TM mode, the second mode is a TE mode.

[0007] In an optional embodiment of the present application, the above-mentioned microring resonant cavity is designed on a silicon platform on an insulating substrate, and the waveguide material of the microring resonant cavity is silicon.

[0008] In an optional embodiment of the present application, the waveguide cross-section of the above-mentioned microring resonator except the first polarization rotator and the second polarization rotator is 340nm×340nm, the cross-sectional size of the trapezoidal cut-angle structure is 160nm×160nm, and the radius of the microring structure is 5μm.

[0009] In an optional embodiment of the present application, the wavelength range of the input light of the microring resonator is 1.5 μm to 1.6 μm.

[0010] In an optional embodiment of the present application, in a silicon waveguide with a cross-section of 340nm×340nm, the effective refractive index of the TM0 mode is 2.3119, the effective refractive index of the TE0 mode is 2.3128, the waveguide's binding ability for TM mode light is weaker than that for TE mode light, and the coupling ability of the TM mode transmitted in the waveguide with other waveguides is stronger than the coupling ability of the TE mode light transmitted in the waveguide with other waveguides.

[0011] In an optional embodiment of the present application, the upper base length of the trapezoidal surface of the trapezoidal cut-angle structure is 1 μm, the lower base length is 5 μm, and the height is 160 nm. The thickness of the trapezoidal cut angle of the trapezoidal cut-angle structure is 160 nm, and the lengths of the first polarization rotator and the second polarization rotator are both 5 μm.

[0012] In an optional embodiment of the present application, when light of the third mode is input from the input waveguide, the light of the third mode is converted into light of the fourth mode after passing through the first polarization rotator; when light of the fourth mode is transmitted to the first coupling region, if the resonance equation of the microring resonant cavity is satisfied, the light of the fourth mode is coupled to the microring structure; among the light of the fourth mode transmitted in the microring structure, a part is coupled to the output waveguide from the second coupling region, and the other part is still transmitted in the microring structure; the light of the fourth mode coupled to the output waveguide is converted into light of the third mode after passing through the second polarization rotator, and the output waveguide finally outputs light of the third mode; wherein, when the third mode is the TE mode, the fourth mode is the TM mode; when the third mode is the TM mode, the fourth mode is the TE mode.

[0013] In an optional embodiment of the present application, the resonance equation of the microring resonant cavity is: Ln eff =mλ, m = 1, 2, 3…; where L is the circumference of the microring structure, n eff is the effective refractive index of the mode in the waveguide, λ is the resonance wavelength, and m is the resonance order.

[0014] In an optional embodiment of the present application, the conversion efficiency of the first polarization rotator and the second polarization rotator is 97.3%.

[0015] In a second aspect, an embodiment of the present invention further provides an optical device, and the optical device includes the above-mentioned microring resonant cavity.

[0016] The embodiments of the present invention bring the following beneficial effects:

[0017] The embodiment of the present invention provides a micro-ring resonant cavity and an optical device, wherein the micro-ring resonant cavity comprises: an input waveguide, a first coupling region, a micro-ring structure, a second coupling region, and an output waveguide; the input waveguide is provided with a first polarization rotator, the output waveguide is provided with a second polarization rotator, and both the first polarization rotator and the second polarization rotator are provided with a trapezoidal cut angle structure; the input waveguide and the output waveguide are arranged in parallel, and the micro-ring structure is arranged between the input waveguide and the output waveguide; when the light of the first mode is transmitted to the first polarization rotator or the second polarization rotator, the first polarization rotator or the second polarization rotator is used to rotate the polarization of the light of the first mode and output the light of the second mode; wherein, when the first mode is a TE mode, the second mode is a TM mode; when the first mode is a TM mode, the second mode is a TE mode. In this way, the light of the first mode can be converted into the second mode by the trapezoidal cut angle structure, and the coupling of the micro-ring resonant cavity can be enhanced by using the stronger coupling ability of the TM mode without changing the performance parameters of the micro-ring structure.

[0018] Other features and advantages of the present disclosure will be set forth in the following description, or some features and advantages may be inferred or unambiguously determined from the description, or may be learned by implementing the above-mentioned technology of the present disclosure.

[0019] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of a racetrack-type microring resonant cavity and a curved coupling-type microring resonant cavity provided in an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the structure of a micro-ring resonant cavity provided by an embodiment of the present invention;

[0023] Figure 3 A schematic diagram of a structure for simulating a micro-ring coupling region provided by an embodiment of the present invention;

[0024] Figure 4 A schematic diagram of the coupling capability of a TM mode and a TE mode provided in an embodiment of the present invention;

[0025] Figure 5 A schematic diagram of a trapezoidal cut-angle structure provided by an embodiment of the present invention;

[0026] Figure 6 A schematic diagram of the conversion efficiency of a TM mode and a TE mode provided in an embodiment of the present invention;

[0027] Figure 7 A schematic diagram of a transmission rate of a first polarization rotator and a second polarization rotator connected end to end provided by an embodiment of the present invention;

[0028] Figure 8 A schematic structural diagram of an optical device provided by an embodiment of the present invention.

[0029] Icon: 1-input waveguide; 2-first polarization rotator; 3-first coupling region; 4-microring structure; 5-second coupling region; 6-second polarization rotator; 7-output waveguide; 8-trapezoidal cut-angle structure. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Currently, see Figure 1 The schematic diagram of a racetrack-type microring resonant cavity and a curved coupling-type microring resonant cavity is shown. The commonly used methods of enhancing coupling in the prior art include reducing the interval between the microring and the input and output waveguides, and using a racetrack-type or curved coupling-type structure in the coupling region to increase the coupling length. Reducing the interval requires relatively high precision in the processing technology; the racetrack-type coupling region structure will affect the structure and performance parameters of the original microring. For example, in an optical communication system, the addition of a racetrack structure will increase the cavity length of the resonant cavity, reduce the free spectrum range of the microring resonant cavity, and reduce the channel capacity; in the curved coupling-type coupling region, the optical signal needs to meet the phase matching condition to couple, and the additional curved waveguide will increase more bending losses, and the design is also more complicated. Therefore, enhancing the coupling ability of the microring structure and the input and output waveguides without changing the performance parameters of the microring structure is a technical problem that needs to be solved urgently.

[0032] Based on this, a microring resonator and an optical device provided in an embodiment of the present invention specifically provide a coupling-enhanced microring resonator based on a polarization rotator, which can convert the first mode of light into the second mode through a trapezoidal cut-angle structure, and enhance the coupling of the microring resonator by utilizing the stronger coupling ability of the TM mode without changing the performance parameters of the microring structure.

[0033] To facilitate understanding of this embodiment, a microring resonant cavity disclosed in an embodiment of the present invention is first introduced in detail.

[0034] Embodiment 1:

[0035] The present invention provides a micro-ring resonant cavity. Figure 2 The schematic diagram of the structure of a micro-ring resonant cavity shown in the figure comprises: an input waveguide 1, a first coupling region 3, a micro-ring structure 4, a second coupling region 5, and an output waveguide 7; the input waveguide 1 is provided with a first polarization rotator 2, the output waveguide 7 is provided with a second polarization rotator 6, and both the first polarization rotator 2 and the second polarization rotator 6 are provided with a trapezoidal cut-angle structure 8; the input waveguide 1 and the output waveguide 7 are arranged in parallel, and the micro-ring structure 4 is arranged between the input waveguide 1 and the output waveguide 7;

[0036] When light of the first mode is transmitted to the first polarization rotator or the second polarization rotator, the first polarization rotator or the second polarization rotator is used to rotate the polarization of the light of the first mode and output light of the second mode; wherein, when the first mode is the TE mode, the second mode is the TM mode; when the first mode is the TM mode, the second mode is the TE mode.

[0037] The first polarization rotator and the second polarization rotator in this embodiment are used to perform mode conversion on input light. For example, light in TM mode input to the first polarization rotator can be converted to TE mode; light in TE mode input to the second polarization rotator can be converted to TM mode.

[0038] Take the example that the first mode is the TE mode and the second mode is the TM mode: Since light of different modes has different coupling capabilities, in this embodiment, the light of the TE mode with poor coupling capability can be converted into light of the TM mode with strong coupling capability through the first polarization rotator and the second polarization rotator, and the light of the TM mode with strong coupling capability is coupled, thereby enhancing the coupling of the microring resonant cavity by utilizing the stronger coupling capability of the TM mode without changing the performance parameters of the microring structure. Then, the light of the TM mode with strong coupling capability is converted into the TE mode, thereby ensuring that the input and output lights have the same mode, that is, the first mode.

[0039] The embodiment of the present invention provides a micro-ring resonant cavity, which includes: an input waveguide, a first coupling region, a micro-ring structure, a second coupling region, and an output waveguide; the input waveguide is provided with a first polarization rotator, the output waveguide is provided with a second polarization rotator, and the first polarization rotator and the second polarization rotator are both provided with a trapezoidal cut angle structure; the input waveguide and the output waveguide are arranged in parallel, and the micro-ring structure is arranged between the input waveguide and the output waveguide; when the light of the first mode is transmitted to the first polarization rotator or the second polarization rotator, the first polarization rotator or the second polarization rotator is used to rotate the polarization of the light of the first mode and output the light of the second mode; wherein, when the first mode is a TE mode, the second mode is a TM mode; when the first mode is a TM mode, the second mode is a TE mode. In this way, the light of the first mode can be converted into the second mode by the trapezoidal cut angle structure, and the coupling of the micro-ring resonant cavity can be enhanced by using the stronger coupling ability of the TM mode without changing the performance parameters of the micro-ring structure.

[0040] Embodiment 2:

[0041] This embodiment provides another micro-ring resonant cavity, which is implemented on the basis of the above embodiment. In some embodiments, the above micro-ring resonant cavity is designed on a silicon platform on an insulating substrate.

[0042] The coupled enhanced micro-ring resonator based on the polarization rotator provided in this embodiment can be designed on a silicon-on-insulator (SOI) platform. The waveguide material is silicon, the buried oxide layer and the upper cladding material are silicon dioxide, and the refractive index of silicon is n Si =3.47, the refractive index of silicon dioxide n SiO2 =1.44.

[0043] In some embodiments, the waveguide sections of the microring resonator other than the first polarization rotator and the second polarization rotator are 340 nm×340 nm, the cross-sectional dimensions of the trapezoidal cut-angle structure are 160 nm×160 nm, and the radius of the microring structure is 5 μm.

[0044] In this embodiment, except for the first polarization rotator 2 and the second polarization rotator 6, the waveguide cross-section of the remaining parts can be 340nm×340nm, and the first polarization rotator 2 and the second polarization rotator 6 can adopt a trapezoidal cut-angle structure 8, as shown in the structure Figure 2 As shown, the cut-angle cross-section size is 160 nm×160 nm, and the radius of the micro-ring structure 4 is set to 5 μm. In addition, the wavelength range of the input light of the micro-ring resonant cavity is 1.5 μm to 1.6 μm.

[0045] The existing methods for enhancing the coupling strength of microrings are designed for the structure of the microring coupling zone. The present invention is designed from the perspective of mode, mainly using the difference in coupling ability between TE mode and TM mode to enhance the coupling strength, without the need for additional design of the coupling zone. Usually, the coupling of TM mode is stronger, because the waveguide has a stronger binding ability for the mode with higher effective refractive index, and the field attenuation in the waveguide cladding can be approximated as:

[0046] where E is the field amplitude at a distance d from the core-cladding interface, n eff is the effective refractive index of the mode, n c is the refractive index of the cladding, and λ is the wavelength of light. It can be seen that the larger the effective refractive index of the mode, the faster the electric field in the cladding decays, indicating that the energy confinement in the waveguide is greater, that is, the waveguide has a stronger ability to bind the mode.

[0047] In a silicon waveguide with a cross section of 340nm×340nm, the effective refractive index of the TM0 mode is 2.3119, and the effective refractive index of the TE0 mode is 2.3128. It can be seen that the waveguide's ability to bind TM mode light is weaker than that of TE mode light. On the other hand, the coupling ability of the TM mode transmitted in the waveguide with other waveguides is stronger than the coupling ability of the TE mode light transmitted in the waveguide with other waveguides. In a waveguide of general size, the effective refractive index of the TM0 mode is lower than that of the TE0 mode. For coupling using the TE0 mode, it can be converted into the TM0 mode or other modes with a smaller effective refractive index to enhance coupling.

[0048] In this embodiment, the micro-ring coupling region is simulated. Figure 3 The schematic diagram of a structure for simulating the microring coupling region is shown. In order to illustrate the difference in TM and TE mode coupling capabilities, the interval between the microring structure and the waveguide is set to 100nm. The TM mode and TE mode light is input from the waveguide end. When it is transmitted to the coupling region with the microring, the light will be coupled to the microring output port. By comparing the laser output transmittance of the microring output port, the coupling capabilities of the TM mode and TE mode can be compared. The output results can be seen in Figure 4 A schematic diagram of the coupling ability of the TM mode and the TE mode. It can be obtained that more TM mode light is coupled to the microring output port. Compared with the TE mode, the transmittance of the TM mode light is increased by nearly 20%, which can be used to enhance the coupling of the microring resonant cavity.

[0049] In this embodiment, the symmetry of the structure can be destroyed by removing a part of the square waveguide, so that mode hybridization occurs between two orthogonal polarizations. Under the influence of mode hybridization, the modes with different polarization directions in the waveguide will have energy level crossover or coupling, thereby achieving polarization rotation of the mode. This implementation example destroys the symmetry of the waveguide structure by cutting a trapezoidal cut angle in the waveguide, see Figure 5 The schematic diagram of a trapezoidal cut-angle structure is shown, the upper base length of the trapezoidal surface of the trapezoidal cut-angle structure is 1μm, the lower base length is 5μm, and the height is 160nm. The thickness of the trapezoidal cut-angle structure is 160nm, and the lengths of the first polarization rotator and the second polarization rotator are both 5μm. The sharp corners on both sides of the trapezoid are to make the mode change slowly when it is transmitted to the cut-angle part, so as to achieve the purpose of reducing loss.

[0050] In some embodiments, the conversion efficiency of the first polarization rotator and the second polarization rotator is 97.3%.

[0051] In this embodiment, TE (TM) polarized light is input into the polarization rotator. The mode conversion efficiency can be seen from Figure 6A schematic diagram of the conversion efficiency of a TM mode and a TE mode is shown. It can be seen that the polarization rotator can rotate the polarization of light and output TM (TE) polarized light. The conversion efficiency of the two polarization modes is about 97.3%.

[0052] In order to ensure the consistency of input and output modes, in this embodiment, a first polarization rotator 2 and a second polarization rotator 6 can be respectively provided in the input waveguide 1 and the output waveguide 7. When TE polarized light is input from the input waveguide 1, it is converted into TM polarized light after passing through the first polarization rotator 2, and finally outputs TE polarized light after passing through the second polarization rotator of the output waveguide 7, thereby achieving that both input and output are TE polarized light. The two polarization rotators are connected end to end, and the overall mode transmission and conversion effect are measured. The results can be seen in Figure 7 The schematic diagram of the transmission rate of a first polarization rotator and a second polarization rotator connected end to end is shown. The polarization mode is well restored, and the overall loss is about 0.08dB, which minimizes the impact of adding the polarization rotator to the microring resonant cavity structure.

[0053] In some embodiments, when light of the third mode is input from the input waveguide, the light of the third mode is converted into light of the fourth mode after passing through the first polarization rotator; when light of the fourth mode is transmitted to the first coupling region, if the resonance equation of the microring resonant cavity is satisfied, the light of the fourth mode is coupled to the microring structure; among the light of the fourth mode transmitted in the microring structure, a part is coupled to the output waveguide from the second coupling region, and the other part is still transmitted in the microring structure; the light of the fourth mode coupled to the output waveguide is converted into light of the third mode after passing through the second polarization rotator, and the output waveguide finally outputs light of the third mode; wherein, when the third mode is the TE mode, the fourth mode is the TM mode; when the third mode is the TM mode, the fourth mode is the TE mode.

[0054] The specific implementation of the microring resonant cavity of the present invention when in use is as follows: TE polarized light is input from the input waveguide 1, and the light is polarized and converted to TM polarization after being transmitted through the first polarization rotator 2, and coupled with the microring structure 4 by utilizing the stronger coupling ability of TM polarized light. When the light is transmitted to the first coupling region 3, only when the resonance equation of the microring resonant cavity is satisfied, that is, the optical path length of the microring waveguide is exactly equal to an integer multiple of the wavelength, can the light enter the microring structure 4 for resonance enhancement. The resonance equation of the microring resonant cavity is: Ln eff =mλ, m = 1, 2, 3…; where L is the circumference of the microring structure, n eff is the effective refractive index of the mode in the waveguide, λ is the resonance wavelength, and m is the resonance order.

[0055] Part of the light transmitted in the micro-ring structure 4 is coupled from the second coupling region 5 to the output waveguide 7, and the rest is still transmitted in the micro-ring structure 4. After the light coupled to the output waveguide 7 passes through the second polarization rotator 6, the TM polarized light is converted into TE polarized light, and finally output as TE polarized light after frequency selection filtering by the micro-ring structure 4.

[0056] From the resonance equation of the microring resonator, it can be seen that the output spectrum contains a series of resonant wavelengths, each resonant wavelength corresponds to a resonant peak, and the interval between two adjacent resonant peaks is called the free spectral range (FSR). The values ​​of FSR are: where n g =n eff -λ(dn eff / dλ), n g is the group refractive index. It can be seen from the formula that the value of FSR is closely related to the circumference of the micro-ring structure 4.

[0057] At present, the commonly used enhanced coupling methods in the prior art are:

[0058] 1. Reduce the interval. When stronger coupling is required, the interval is too small and the processing is incompatible.

[0059] 2. A racetrack-type structure is adopted in the coupling region, the overall structure is widened, and the circumference of the microring is increased, which affects the resonant wave and free spectrum range of the microring resonant cavity.

[0060] 3. The coupling zone adopts a curved coupling structure, which is complex in design and requires phase matching conditions to couple. When there is a phase mismatch, coupling almost does not occur. The phase matching conditions are R1n eff1 =R2n eff2 , where R1, R2 and n eff1 、n eff2 is the radius and effective refractive index of the two arcs where coupling occurs. eff Closely related to the waveguide width, the radius of the arc inside and outside the coupling zone and the waveguide width need to be optimized simultaneously to meet the phase matching conditions. The micro-ring waveguide width is relatively wide, which usually involves high-order modes, increasing the loss in the process of light transmission. The two additional arc waveguides added to the input and output waveguides will lead to an increase in bending loss. In addition to the arc radius and waveguide width, the coupling length of the coupling zone needs to be optimized at the same time to achieve the strongest coupling, and the design is relatively complicated.

[0061] Existing methods for enhancing the coupling of microring resonant cavities are designed for the microring coupling region structure, and the coupling is enhanced by increasing the coupling length of the coupling region. The embodiments of the present invention can be designed from the perspective of mode coupling capability without changing the performance parameters of the original microring structure.

[0062] The coupled enhanced micro-ring resonator based on the polarization rotator provided by the embodiment of the present invention has a small difference in the effective refractive index of the two polarization modes, which hardly affects the performance parameters of the micro-ring structure, and the structure can realize the mutual conversion of TE and TM modes. The conversion efficiency of the polarization rotator is about 97.3%, and the polarization mode remains unchanged after the light passes through two polarization rotators continuously, with a loss of about 0.08dB, which can be used at the input and output ends to ensure low-loss transmission of light.

[0063] The micro-ring resonant cavity structure provided in the embodiment of the present invention can convert the TE mode into the TM mode by only designing the size of a trapezoidal cut-angle structure in the waveguide, and utilize the stronger coupling ability of the TM mode to enhance the coupling of the micro-ring resonant cavity.

[0064] Therefore, for a microring resonant cavity whose working mode is TE mode, in this embodiment, it can be converted into TM mode through a polarization rotator with a trapezoidal cut-angle structure, and the stronger coupling ability of the TM mode can be used to enhance the coupling of the microring resonant cavity without changing the performance parameters of the microring structure.

[0065] Embodiment three:

[0066] Corresponding to the above embodiment, an embodiment of the present invention provides an optical device, see Figure 8 A schematic structural diagram of an optical device is shown, wherein the optical device includes the micro-ring resonant cavity provided in the aforementioned embodiment.

[0067] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the optical device described above can refer to the corresponding process in the aforementioned embodiment of the microring resonator, and will not be repeated here.

[0068] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0070] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A microring resonator, characterized in that: The microring resonant cavity comprises: an input waveguide, a first coupling region, a microring structure, a second coupling region, and an output waveguide; the input waveguide is provided with a first polarization rotator, the output waveguide is provided with a second polarization rotator, and both the first polarization rotator and the second polarization rotator are provided with a trapezoidal cut-angle structure; the input waveguide and the output waveguide are arranged in parallel, and the microring structure is arranged between the input waveguide and the output waveguide; When the light of the first mode is transmitted to the first polarization rotator or the second polarization rotator, the first polarization rotator or the second polarization rotator is used to rotate the polarization of the light of the first mode and output the light of the second mode; wherein, when the first mode is the TE mode, the second mode is the TM mode; when the first mode is the TM mode, the second mode is the TE mode; The microring resonator is designed on a silicon platform on an insulating substrate; the waveguide cross-section of the microring resonator except the first polarization rotator and the second polarization rotator is 340nm×340nm, the cross-sectional size of the trapezoidal cut-angle structure is 160nm×160nm, and the radius of the microring structure is 5μm.

2. The microring resonator according to claim 1, characterized in that: The wavelength of the input light of the micro-ring resonator is in the range of 1.5 μm to 1.6 μm.

3. The microring resonator according to claim 1, characterized in that: In a silicon waveguide with a cross-section of 340nm×340nm, the effective refractive index of the TM0 mode is 2.3119, and the effective refractive index of the TE0 mode is 2.3128. The waveguide's ability to bind TM mode light is weaker than that of TE mode light. The coupling ability of the TM mode transmitted in the waveguide with other waveguides is stronger than the coupling ability of the TE mode light transmitted in the waveguide with other waveguides.

4. The microring resonator according to claim 1, characterized in that: The upper base length of the trapezoidal surface of the trapezoidal cut corner structure is 1 μm, the lower base length is 5 μm, and the height is 160 nm. The thickness of the trapezoidal cut corner of the trapezoidal cut corner structure is 160 nm. The lengths of the first polarization rotator and the second polarization rotator are both 5 μm.

5. The microring resonator according to claim 1, characterized in that: When light in a third mode is input from the input waveguide, the light in the third mode is converted into light in a fourth mode after passing through the first polarization rotator; When the light of the fourth mode is transmitted to the first coupling region, if the resonance equation of the microring resonant cavity is satisfied, the light of the fourth mode is coupled with the microring structure; Among the light of the fourth mode transmitted in the microring structure, a part is coupled from the second coupling region to the output waveguide, and another part is still transmitted in the microring structure; The fourth mode light coupled into the output waveguide is converted into the third mode light after passing through the second polarization rotator, and the output waveguide finally outputs the third mode light; When the third mode is the TE mode, the fourth mode is the TM mode; when the third mode is the TM mode, the fourth mode is the TE mode.

6. The microring resonator according to claim 5, characterized in that: The resonance equation of the micro-ring resonator is: Ln eff =mλ, m = 1, 2, 3…; where L is the circumference of the microring structure, n eff is the effective refractive index of the mode in the waveguide, λ is the resonance wavelength, and m is the resonance order.

7. The microring resonator according to claim 1, characterized in that: The conversion efficiency of the first polarization rotator and the second polarization rotator is 97.3%.

8. An optical device, characterized in that: The optical device comprises the microring resonator according to any one of claims 1-7.

Images