A third-order singular point optical isolator based on microring resonator

Abstract

The present invention discloses a third-order singular point optical isolator based on a microring resonator, comprising a lower cladding, a bus waveguide and a microring resonator. The microring resonator comprises three annular waveguides of identical size, which are evenly spaced and distributed on the first lower cladding in a sequence from front to back. A YIG seed layer is deposited on the upper end face of the third annular waveguide, and a magneto-optical material layer is formed by depositing a magneto-optical material with a Faraday rotation angle greater than 3000° / cm on the YIG seed layer. Both the YIG seed layer and the magneto-optical material layer are annular structures coaxial with the third annular waveguide, and their inner diameters are equal to the inner diameter of the third annular waveguide, and their outer diameters are equal to the outer diameter of the third annular waveguide. The microring resonator has the advantages of small size, high isolation ratio and large isolation bandwidth.

Description

Technical Field

[0001] The present invention relates to an optical isolator, in particular to a third-order singular point optical isolator based on a microring resonator. Background Art

[0002] Currently, the vast majority of information in communication systems is transmitted and processed by electronic circuits. However, the Coulomb force between electrons and their susceptibility to interference from the electromagnetic environment severely limit the speed and capacity of communication systems. In contrast, photons do not interact with each other, are highly resistant to electromagnetic interference, and have transmission rates far exceeding those of electrons. Using photons as the fundamental carrier of communication systems offers significant advantages. Photonic integration technology has played a vital role in today's information society. However, the design of photonic integrated devices in various optical systems faces the challenge of how to deal with backscattered and reflected light. Backlight can induce noise in photonic integrated devices, distorting information, and even causing changes in signal frequency and amplitude, reducing the stability of the optical system.

[0003] An optical isolator, also known as a "photodiode," is a photonic integrated device that can isolate backscattered light and reverse light. In an optical isolator, light is transmitted only in a single direction, effectively isolating reverse light and ensuring stable operation of the optical system. Key performance indicators for optical isolators include isolation ratio, insertion loss, and isolation bandwidth at varying degrees of isolation. Improving these performance indicators is a key development direction in optical isolator research.

[0004] The ring optical isolator based on microring resonator is a common optical isolator currently. It uses non-reciprocal phase shift (NRPS) to make the phase of forward light and reverse light inconsistent, and the resonance peak is shifted, which leads to smaller loss of forward light and larger loss of reverse light in a certain wavelength range, thereby achieving isolation within a certain wavelength range. Existing ring optical isolators based on microring resonators are small in size and have a high isolation ratio. However, due to the narrow bandwidth resonance characteristics of the microring resonator, the wavelength range (isolation bandwidth) in which it can achieve isolation is limited, and the isolation bandwidth is usually less than 5GHz. However, a larger isolation bandwidth can bring more ample working conditions to other photonic integrated devices in the optical system, and can be applied to optical systems with other wavelength light sources. Therefore, due to the limitation of the isolation bandwidth, the application of existing ring optical isolators based on microring resonators is also greatly restricted. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a third-order singular point optical isolator based on a microring resonator which has a small size, a high isolation ratio and a large isolation bandwidth.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a third-order singular point optical isolator based on a microring resonator, comprising a lower cladding, a bus waveguide and a microring resonator, wherein the bus waveguide and the microring resonator are respectively attached to the lower cladding, the lower cladding is a rectangular parallelepiped structure, the length direction of the lower cladding is defined as the left-right direction, the width direction is defined as the front-back direction, and the thickness direction is defined as the up-down direction, the bus waveguide is a rectangular parallelepiped structure, and its length is along the left-right direction, the width is along the front-back direction, and the thickness is along the up-down direction, the left end of the bus waveguide is The surface of the bus waveguide is flush with the left end surface of the lower cladding, the right end surface of the bus waveguide is flush with the right end surface of the lower cladding, the front end surface of the bus waveguide is located on the rear side of the plane where the front end surface of the lower cladding is located, and there is a distance between the two, and the lower end surface of the bus waveguide is in a fit state with the upper end surface of the lower cladding; the microring resonator includes three ring waveguides with exactly the same size, and the three ring waveguides are evenly spaced from front to back on the first lower cladding, and the lower end surface of each ring waveguide is in a fit state with the upper end surface of the lower cladding. The upper end faces of the three ring waveguides are located in the same plane as the upper end face of the bus waveguide, the central axes of the three ring waveguides are located in the same plane, and the plane makes the lower cladding symmetrical. The outer diameter of each ring waveguide is smaller than the length of the lower cladding, the difference between the outer diameter and the inner diameter of each ring waveguide is equal to the width of the bus waveguide, and the diameter of each ring waveguide is smaller than the length of the lower cladding. The three ring waveguides are referred to as the first ring waveguide, the second ring waveguide, and the third ring waveguide from front to back. The first ring waveguide is located on the rear side of the bus waveguide, and There is a distance between the two, the third ring waveguide is located on the front side of the plane where the rear end face of the lower cladding is located, and there is a distance between the two, a YIG seed layer is deposited on the upper end face of the third ring waveguide, and a magneto-optical material layer is formed on the YIG seed layer by depositing magneto-optical material with a Faraday rotation angle greater than 3000° / cm. The YIG seed layer and the magneto-optical material layer are both annular structures coaxial with the third ring waveguide, and their inner diameters are equal to the inner diameter of the third ring waveguide, and their outer diameters are equal to the outer diameter of the third ring waveguide.

[0007] Compared with the prior art, the advantage of the present invention is that a microring resonator is formed by three ring waveguides of exactly the same size, the microring resonator has a simple structure, the three ring waveguides are evenly spaced on the first lower cladding in order from front to back, and the three ring waveguides are called the first ring waveguide, the second ring waveguide and the third ring waveguide in order from front to back, a YIG seed layer is deposited on the upper end surface of the third ring waveguide, a magneto-optical material layer is formed by depositing a magneto-optical material with a Faraday rotation angle greater than 3000° / cm on the YIG seed layer, the first ring waveguide, the second ring waveguide and the third ring waveguide form a three-ring series structure, the third ring waveguide, the YIG seed layer and the magneto-optical material layer together form a ring magneto-optical waveguide, the bus waveguide and the adjacent part of the first ring waveguide form a first directional coupler, the first ring waveguide and the adjacent part of the second ring waveguide form a second directional coupler, and the second ring waveguide and the adjacent part of the ring magneto-optical waveguide form a third directional coupler; when a magnetic field is applied above the magneto-optical material layer in the direction pointing to the magneto-optical material, When the magnetic field is in the direction of the center line of the material layer, the magneto-optical waveguide will produce a non-reciprocal phase shift, and the light incident from the left end face of the bus waveguide is regarded as the forward light, and the light incident from the right end face is regarded as the reverse light. For the forward light and the reverse light incident on the bus waveguide at the same time, the forward light and the reverse light are first coupled into the first ring waveguide through the first directional coupler, and then transmitted in the first ring waveguide in the clockwise direction and counterclockwise direction respectively. When the forward light and the reverse light are transmitted to the coupling area between the first ring waveguide and the second ring waveguide, The second directional coupler is coupled to the second ring waveguide, and then the forward light and the reverse light are transmitted in the second ring waveguide in the counterclockwise direction and the clockwise direction, respectively. When the forward light and the reverse light are transmitted to the coupling region between the second ring waveguide and the magneto-optical waveguide, they are coupled to the magneto-optical waveguide through the third directional coupler, and then transmitted in the magneto-optical waveguide in the clockwise direction and the counterclockwise direction, respectively. They are then coupled into the second ring waveguide, the first ring waveguide, and the bus waveguide in sequence, and finally the forward light and the reverse light are output from both ends of the bus waveguide respectively.When forward and reverse light propagate in different directions within the magneto-optical waveguide, the magneto-optical waveguide exhibits different resonant frequencies due to nonreciprocal phase shift. One of the resonant frequencies of the magneto-optical waveguide is the same as the resonant frequencies of the first and second ring waveguides, and is in an EP state. At this point, for a lossy optical isolator, light in the direction corresponding to the resonant frequency of the magneto-optical waveguide, i.e., the reverse light, exhibits a resonant peak in the spectrum, while light in the direction corresponding to the other resonant frequency of the magneto-optical waveguide, i.e., the forward light, exhibits a split resonant peak. This difference in the spectrum between the forward and reverse light results in less loss for the forward light and greater optical power output, while greater loss for the reverse light results in almost no optical power output. This achieves isolation of the reverse light, resulting in a high degree of isolation and a wide isolation bandwidth. Simulation results show that the present invention has an isolation degree greater than 40 dB and an isolation bandwidth exceeding 14 GHz. Therefore, the present invention has a small size, a high isolation ratio, and a large isolation bandwidth.

[0008] Furthermore, the magneto-optical material is Ce:YIG or Bi:YIG, the material of the lower cladding is SiO2, and the materials of the bus waveguide and the three ring waveguides are all active materials or all passive materials.

[0009] Furthermore, the active material is InGaAsP or erbium-doped Si, and the passive material is Si, SiN or lithium niobate.

[0010] Furthermore, an upper cladding layer is provided on the bus waveguide and the three ring waveguides to completely cover them, and the refractive index of the material of the upper cladding layer is lower than the refractive index of the material of the ring waveguides.

[0011] Furthermore, the material of the upper cladding layer is air or SiO2.

[0012] Furthermore, the bus waveguide, the first ring waveguide, the second ring waveguide and the third ring waveguide have a width of 1000 nm and a thickness of 400 nm, the thickness of the YIG seed layer is 30 nm, the thickness of the magneto-optical material layer is 150 nm, the width of the YIG seed layer and the magneto-optical material layer are both 400 nm, the inner diameter of the first ring waveguide, the second ring waveguide and the third ring waveguide are all 72.8 um, and the outer diameter is 73.8 um. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a structural diagram of the third-order singular point optical isolator based on a microring resonator of the present invention;

[0014] Figure 2 A top view of the third-order singular point optical isolator based on a microring resonator according to the present invention;

[0015] Figure 3 A cross-sectional view of a ring magneto-optical waveguide of a third-order singular point optical isolator based on a microring resonator according to the present invention;

[0016] Figure 4 This is a forward light and reverse light spectrum diagram of the third-order singular point optical isolator based on the microring resonator of the present invention;

[0017] Figure 5 is the isolation bandwidth and δ of the optical isolator mo relationship diagram;

[0018] Figure 6 This is a diagram showing the electric field intensity distribution inside the annular magneto-optical waveguide of the third-order singular point optical isolator based on the microring resonator of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0020] Example 1: Figures 1 to 3As shown, a third-order singular point optical isolator based on a microring resonator includes a lower cladding 5, a bus waveguide 1 and a microring resonator. The bus waveguide 1 and the microring resonator are respectively attached to the lower cladding 5. The lower cladding 5 is a rectangular parallelepiped structure. The length direction of the lower cladding 5 is defined as the left-right direction, the width direction is defined as the front-back direction, and the thickness direction is defined as the up-down direction. The bus waveguide 1 is a rectangular parallelepiped structure, and its length is along the left-right direction, the width is along the front-back direction, and the thickness is along the up-down direction. The left end face of the bus waveguide 1 is flush with the left end face of the lower cladding 5. The right end face of the bus waveguide 1 is flush with the right end face of the lower cladding 5, the front end face of the bus waveguide 1 is located on the rear side of the plane where the front end face of the lower cladding 5 is located, and there is a distance between the two, and the lower end face of the bus waveguide 1 is in contact with the upper end face of the lower cladding 5; the microring resonator includes three ring waveguides with exactly the same size, and the three ring waveguides are evenly spaced and distributed on the first lower cladding 5 in order from front to back, and the lower end face of each ring waveguide is in contact with the upper end face of the lower cladding 5, and the upper end face of each ring waveguide is in contact with the bus waveguide. The upper end surface of the bus waveguide 1 is located in the same plane, the central axes of the three ring waveguides are located in the same plane, and the plane makes the lower cladding 5 bilaterally symmetrical. The outer diameter of each ring waveguide is smaller than the length of the lower cladding 5, the difference between the outer diameter and the inner diameter of each ring waveguide is equal to the width of the bus waveguide 1, and the diameter of each ring waveguide is smaller than the length of the lower cladding 5. The three ring waveguides are called the first ring waveguide 2, the second ring waveguide 3 and the third ring waveguide 4 from front to back. The first ring waveguide 2 is located at the rear side of the bus waveguide 1, and the distance between the two is smaller than the length of the lower cladding 5. There is a distance between them, the third ring waveguide 4 is located on the front side of the plane where the rear end face of the lower cladding 5 is located, and there is a distance between the two, a YIG seed layer 6 is deposited on the upper end face of the third ring waveguide 4, and a magneto-optical material layer 7 is formed on the YIG seed layer 6 by depositing magneto-optical material with a Faraday rotation angle greater than 3000° / cm. The YIG seed layer 6 and the magneto-optical material layer 7 are both annular structures coaxial with the third ring waveguide 4, and their inner diameters are equal to the inner diameter of the third ring waveguide 4, and their outer diameters are equal to the outer diameter of the third ring waveguide 4.

[0021] In this embodiment, the first ring waveguide 2, the second ring waveguide 3 and the third ring waveguide 4 constitute a three-ring series structure, the third ring waveguide 4, the YIG seed layer 6 and the magneto-optical material layer 7 together constitute a ring magneto-optical waveguide 8, the bus waveguide 1 and the adjacent part of the first ring waveguide 2 form a first directional coupler 9, the first ring waveguide 2 and the adjacent part of the second ring waveguide 3 form a second directional coupler 10, and the second ring waveguide 3 and the adjacent part of the ring magneto-optical waveguide 8 form a third directional coupler 11; when a magnetic field 12 with a magnetic field direction pointing to the center line direction of the magneto-optical material layer 7 is applied above the magneto-optical material layer 7, the magnetic The optical waveguide 8 will produce a non-reciprocal phase shift, and the light incident from the left end face of the bus waveguide 1 is regarded as the forward light, and the light incident from the right end face is regarded as the reverse light. For the forward light and the reverse light incident on the bus waveguide 1 at the same time, the forward light and the reverse light are first coupled into the first ring waveguide 2 through the first directional coupler 9, and then transmitted in the first ring waveguide 2 in a clockwise direction and a counterclockwise direction, respectively. When the forward light and the reverse light are transmitted to the coupling region between the first ring waveguide 2 and the second ring waveguide 3, they are coupled into the second ring waveguide 3 through the second directional coupler 10, and then transmitted in the second ring waveguide 3 in a counterclockwise direction and a clockwise direction, respectively. The forward light and the reverse light are transmitted in the clockwise direction. When the forward light and the reverse light are transmitted to the coupling area of ​​the second ring waveguide 3 and the magneto-optical waveguide 8, they are coupled into the magneto-optical waveguide 8 through the third directional coupler 11, and then transmitted in the magneto-optical waveguide 8 in the clockwise direction and the counterclockwise direction, respectively. Then, they are coupled into the second ring waveguide 3, the first ring waveguide 2 and the bus waveguide 1 in sequence. Finally, the forward light and the reverse light are output from the two ends of the bus waveguide 1 respectively. When the forward light and the reverse light are transmitted in different directions in the magneto-optical waveguide 8, due to the non-reciprocal phase shift, the magneto-optical waveguide 8 will present different resonant frequencies. One of the magneto-optical waveguide 8 The resonant frequency is the same as the resonant frequency of the first ring waveguide 2 and the second ring waveguide 3, and is in the EP state. At this time, for the optical isolator with loss, the light in the direction corresponding to the resonant frequency of the magneto-optical waveguide 8, that is, the reverse light, has a resonance peak in the spectrum, and the light in the direction corresponding to the other resonant frequency of the magneto-optical waveguide 8, that is, the resonance peak of the forward light will be split. This difference in the spectrum between the forward light and the reverse light results in less loss of the forward light and greater optical power output, while the loss of the reverse light is greater and there is almost no optical power output, thereby achieving isolation of the reverse light, greater isolation, and a wider isolation bandwidth.

[0022] The third-order singular point optical isolator based on a microring resonator in this embodiment is implemented by relying on the nonreciprocal phase shift generated by the magneto-optical material to which a magnetic field 12 is applied. Due to the existence of the nonreciprocal phase shift, the reverse light will exhibit a propagation constant different from that of the forward light when transmitting in the magneto-optical waveguide 8. Therefore, the propagation constant of the reverse light will disrupt the original working state of the optical isolator, exhibiting a frequency characteristic different from that of the forward light. The forward light exhibits a smaller loss in the spectrum, while the reverse light exhibits a larger loss in the spectrum, thus achieving isolation.

[0023] Example 2: This example is essentially the same as Example 1, except that: in this example, the magneto-optical materials are Ce:YIG or Bi:YIG, the lower cladding layer 5 is made of SiO2, and the bus waveguide 1 and the three ring waveguides are all made of either active or passive materials. The active material is InGaAsP or erbium-doped Si, and the passive material is Si, SiN, or lithium niobate.

[0024] In this embodiment, when the bus waveguide 1 and the three ring waveguides are made of active materials, when the third-order singular point optical isolator is working, optical loss can be reduced and even gain increase (light amplification) can be achieved by applying pump light to the active materials.

[0025] Example 3: This example is essentially the same as Example 2, except that in this example, an upper cladding layer is further provided over the bus waveguide 1 and the three ring waveguides to completely enclose them. The refractive index of the upper cladding layer is lower than that of the ring waveguide material. The upper cladding layer is made of air or SiO2.

[0026] Example 4: This example is essentially the same as Example 3, except that: in this example, the bus waveguide 1, first ring waveguide 2, second ring waveguide 3, and third ring waveguide 4 are all 1000 nm wide and 400 nm thick; the YIG seed layer 6 is 30 nm thick, the magneto-optical material layer 7 is 150 nm thick, and both the YIG seed layer 6 and the magneto-optical material layer 7 are 400 nm wide; the inner diameters of the first ring waveguide 2, second ring waveguide 3, and magneto-optical waveguide 8 are all 72.8 μm, and the outer diameters are all 73.8 μm. The bus waveguide 1, first ring waveguide 2, second ring waveguide 3, and third ring waveguide 4 are all made of SiN.

[0027] In this embodiment, the magneto-optical waveguide 8 can achieve a non-reciprocal phase shift of π / 2.

[0028] The third-order singular point optical isolator based on the microring resonator of this embodiment is simulated, and its forward light and reverse light spectrum are shown as follows: Figure 4 As shown, the electric field intensity distribution diagram inside the annular magneto-optical waveguide 8 is as follows Figure 6 As shown, analysis Figure 4It can be seen that the isolation of the third-order singular point optical isolator based on the microring resonator of the present invention is greater than 40dB, and the isolation bandwidth can reach 14GHz. Figure 6 It can be seen that the magneto-optical waveguide 8 is a single-mode waveguide, and there is a sufficiently large electric field component in the magneto-optical material layer 7, so that the magneto-optical waveguide can generate a non-reciprocal phase shift of 3409 rad / m.

[0029] In the third-order singular point optical isolator based on the microring resonator of the present invention, the loss rate of the first ring waveguide 2 is recorded as f1, the loss rate of the second ring waveguide 3 is recorded as γ2, the loss rate of the ring magneto-optical waveguide 8 is recorded as γ3, and the coupling rate of the first directional coupler 9 is recorded as γ a The coupling ratio of the second directional coupler 10 is denoted as k, and the coupling ratio of the third directional coupler 11 is denoted as k. The bus waveguide 1 and the three ring waveguides of the optical isolator can be made of active or passive materials according to different operating requirements. The loss and gain of the bus waveguide 1 and the three ring waveguides can be adjusted by adjusting the intensity of the applied pump light. Depending on the selected materials and the location of the applied pump light, the third-order singular point optical isolator based on a microring resonator of the present invention can be designed in the following three ways according to the requirements of isolation bandwidth or insertion loss:

[0030] Design 1: The bus waveguide 1, the first ring waveguide 2, the second ring waveguide 3, and the third ring waveguide 4 are all made of active materials: InGaAsP, erbium-doped Si, etc. Pump light is applied to the first ring waveguide 2 and the second ring waveguide 3, so that the first ring waveguide 2 exhibits gain (γ1 < 0) and the second ring waveguide 3 exhibits neutrality (no loss and no gain, i.e., γ2 = 0). And let γ a =-γ3-γ1, Under this design, since the first ring waveguide 2 is in a gain state, the optical isolator has no insertion loss and achieves light amplification. At the same time, due to the amplification of light, the reverse light after splitting still has a large gain, thereby reducing the width that can achieve effective isolation, resulting in it having a minimum isolation bandwidth.

[0031] Second design: The bus waveguide 1, the first ring waveguide 2, the second ring waveguide 3, and the third ring waveguide 4 are all made of active materials: InGaAsP, erbium-doped Si, etc. Pump light is applied to the second ring waveguide 3, making it neutral (no loss and no gain, i.e., γ2 = 0). And let γ a =γ3+γ1, In this design, since the loss of the second ring waveguide 3 is 0, the optical isolator has a lower insertion loss. The lower loss also makes the difference between the forward optical power and the reverse optical power after splitting larger, thereby giving it the largest isolation bandwidth.

[0032] The third design: bus waveguide 1, first ring waveguide 2, second ring waveguide 3 and third ring waveguide 4 are all made of passive materials: Si, SiN, lithium niobate, etc. No pump light is applied, and γ a =γ3+γ1-2γ2, Compared to the first and second designs, this design lacks any pump light, so the optical isolator does not amplify light, resulting in the highest insertion loss. Furthermore, the optical power difference between the forward and reverse light required to achieve isolation lies between the first and second designs, resulting in a moderate isolation bandwidth.

[0033] For the first design, when light is transmitted in the forward direction, temperature tuning is used to synchronize the natural frequencies of the first ring waveguide 2, the second ring waveguide 3, and the magneto-optical waveguide 8. At this point, only one resonance peak appears in the spectrum. However, when light is transmitted in the reverse direction, the natural frequency of the magneto-optical waveguide 8 changes due to the nonreciprocal phase shift induced by the magnetic field, resulting in a splitting of the resonance peak. For the second and third designs, when light is transmitted in the reverse direction, temperature tuning is used to synchronize the natural frequencies of the first ring waveguide 2, the second ring waveguide 3, and the magneto-optical waveguide 8. At this point, only one resonance peak appears in the spectrum. However, when light is transmitted in the forward direction, the natural frequency of the magneto-optical waveguide 8 changes due to the nonreciprocal phase shift induced by the magnetic field, resulting in a splitting of the resonance peak. For all three designs, the splitting of the resonance peak is proportional to the cube root of the nonreciprocal phase shift, meaning that the isolation bandwidth is also proportional to the cube root of the nonreciprocal phase shift. Therefore, when the nonreciprocal phase shift is small, the optical isolator can achieve an increase in isolation bandwidth. Different designs will have different isolation bandwidths and insertion losses. But generally speaking, no matter which design method is used, the isolation bandwidth can be increased.

[0034] Although the above three designs have different isolation bandwidths, they can all reach above 14 GHz. However, the isolation bandwidth of optical isolators based on microring resonators is generally less than 5 GHz, making them difficult to apply to optical systems with different laser wavelengths. mo The relationship diagram is as follows Figure 5 As shown, δ mo is the frequency change caused by the non-reciprocal phase shift. Since the optical isolator of the present invention is composed of three microring resonators connected in series, the system formed is a third-order EP system. Furthermore, the isolation bandwidth is also proportional to the cube root of the perturbation. Figure 5 As can be seen from the figure, the optical isolator of the present invention has a larger isolation bandwidth than the second-order EP isolator composed of double microrings, and the isolation bandwidth is mo Therefore, even in δ mo When the bandwidth is small, the optical isolator of the present invention can still have a large isolation bandwidth.

[0035] In summary, the third-order singular point optical isolator based on microring resonator of the present invention constructs a third-order EP system so that the isolation bandwidth of the optical isolator is proportional to the cube root of the non-reciprocal phase shift, thereby increasing the isolation bandwidth to 14 GHz. In addition, the third-order singular point optical isolator based on microring resonator of the present invention can realize three different designs as needed to achieve different insertion losses and isolation bandwidths, and the third design does not require gain materials and pump light, and the integration difficulty is lower. The application of the third-order singular point optical isolator based on microring resonator of the present invention in integrated optics can isolate the optical system distortion and optical noise caused by reverse light. And because the third-order singular point optical isolator based on microring resonator of the present invention realizes a large isolation bandwidth, it can simultaneously realize optical isolation in a larger wavelength range, making the optical isolator suitable for a wider range of working environments. The structure and materials of the third-order singular point optical isolator based on microring resonator of the present invention can be manufactured by standard CMOS process, and can achieve large-scale integration.

Claims

1. A third-order singular point optical isolator based on a microring resonator, comprising a lower cladding, a bus waveguide and a microring resonator, wherein the bus waveguide and the microring resonator are respectively attached to the lower cladding, and the lower cladding is a rectangular parallelepiped structure, wherein the length direction of the lower cladding is defined as the left-right direction, the width direction is defined as the front-back direction, and the thickness direction is defined as the up-down direction. The bus waveguide is a rectangular parallelepiped structure, and its length is along the left-right direction, the width is along the front-back direction, and the thickness is along the up-down direction. The left end face of the bus waveguide is flush with the left end face of the lower cladding, the right end face of the bus waveguide is flush with the right end face of the lower cladding, the front end face of the bus waveguide is located on the rear side of the plane where the front end face of the lower cladding is located, and there is a distance between the two, and the lower end face of the bus waveguide is in a bonded state with the upper end face of the lower cladding; characterized in that The microring resonator includes three annular waveguides of exactly the same size, and the three annular waveguides are evenly spaced and distributed on the lower cladding in a sequence from front to back. The lower end face of each annular waveguide is in a state of contact with the upper end face of the lower cladding, and the upper end face of each annular waveguide is located in the same plane as the upper end face of the bus waveguide. The central axes of the three annular waveguides are located in the same plane, and the plane makes the lower cladding bilaterally symmetrical. The outer diameter of each annular waveguide is smaller than the length of the lower cladding, the difference between the outer diameter and the inner diameter of each annular waveguide is equal to the width of the bus waveguide, and the diameter of each annular waveguide is smaller than the length of the lower cladding. The three annular waveguides are referred to as the first annular waveguide from front to back. waveguide, a second ring waveguide and a third ring waveguide, the first ring waveguide is located on the rear side of the bus waveguide, and there is a distance between the two, the third ring waveguide is located on the front side of the plane where the rear end face of the lower cladding is located, and there is a distance between the two, a YIG seed layer is deposited on the upper end face of the third ring waveguide, a magneto-optical material layer is formed by depositing a magneto-optical material with a Faraday rotation angle greater than 3000° / cm on the YIG seed layer, the YIG seed layer and the magneto-optical material layer are both annular structures coaxial with the third ring waveguide, and their inner diameters are equal to the inner diameter of the third ring waveguide, and their outer diameters are equal to the outer diameter of the third ring waveguide.

2. The third-order singular point optical isolator based on a microring resonator according to claim 1, characterized in that The magneto-optical material is Ce:YIG or Bi:YIG, the material of the lower cladding is SiO2, and the materials of the bus waveguide and the three ring waveguides are all active materials or passive materials.

3. The third-order singular point optical isolator based on a microring resonator according to claim 2, characterized in that The active material is InGaAsP or erbium-doped Si, and the passive material is Si, SiN or lithium niobate.

4. A third-order singular point optical isolator based on a microring resonator according to any one of claims 1 to 3, characterized in that The bus waveguide and the three ring waveguides are further provided with an upper cladding layer which completely covers the bus waveguide and the three ring waveguides. The refractive index of the material of the upper cladding layer is lower than the refractive index of the material of the ring waveguide.

5. The third-order singular point optical isolator based on a microring resonator according to claim 4, characterized in that The material of the upper cladding layer is air or SiO2.

6. The third-order singular point optical isolator based on a microring resonator according to claim 1, characterized in that The bus waveguide, the first ring waveguide, the second ring waveguide and the third ring waveguide have a width of 1000 nm and a thickness of 400 nm. The thickness of the YIG seed layer is 30 nm, the thickness of the magneto-optical material layer is 150 nm, the width of the YIG seed layer and the magneto-optical material layer are both 400 nm, and the inner diameters of the first ring waveguide, the second ring waveguide and the third ring waveguide are all 72.8 um and the outer diameters are all 73.8 um.

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