Three-order singular point optical isolator based on micro-ring resonator

Abstract

The invention discloses a micro-ring resonator-based third-order singular point optical isolator, which comprises lower cladding layers, a bus waveguide and a micro-ring resonator, and is characterized in that the micro-ring resonator comprises three annular waveguides with the same size, and the three annular waveguides are uniformly distributed on the first lower cladding layer at intervals in sequence from front to back; a YIG seed layer is deposited on the upper end face of the third annular waveguide, a magneto-optical material layer is formed on the YIG seed layer by depositing magneto-optical materials with the Faraday rotation angle larger than 3000 degrees / cm, the YIG seed layer and the magneto-optical material layer are both of an annular structure coaxial with the third annular waveguide, and the inner diameter of the YIG seed layer and the inner diameter of the magneto-optical material layer are both equal to the inner diameter of the third annular waveguide. The outer diameter is equal to that of the third annular waveguide; the filter has the advantages of being small in size, high in isolation ratio and large in isolation bandwidth.

Description

Technical Field

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

[0002] At present, most of the information in communication systems is transmitted and processed by electronic circuits. However, due to the Coulomb force between electrons and the susceptibility to interference from the electromagnetic environment, the rate and capacity of the communication system are severely limited. In contrast, there is no interaction between photons, and they have strong anti-electromagnetic interference capabilities. The transmission rate is much higher than that of electrons. Using photons as the basic carrier of communication systems has great advantages. Photonic integration technology has played an important role in the current information society. However, when designing various photonic integrated devices for various optical systems, we are faced with the problem of how to deal with backscattered light and reflected light. Backlight will cause noise in photonic integrated devices, causing distortion of information in photonic integrated devices, and even causing changes in signal frequency and amplitude, reducing the stability of the optical system.

[0003] An optical isolator is a photonic integrated device that can isolate backscattered light and reverse light, also known as a "photodiode". In an optical isolator, light is only allowed to transmit in a single direction, thereby effectively isolating reverse light to ensure the stable operation of the optical system. The main performance indicators of an optical isolator include isolation ratio, insertion loss, and isolation bandwidth at different isolation levels. In the research of optical isolators, the improvement of the above performance indicators is the main development direction.

[0004] The ring optical isolator based on microring resonator is a common optical isolator at present. 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 a smaller loss of forward light and a larger loss of reverse light in a certain wavelength range, thereby achieving isolation within a certain wavelength range. The existing ring optical isolation devices based on microring resonators are small in size and high in 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 micro-ring resonator which has a small volume, 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, and the left end of the bus waveguide is 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 at 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 contact with the upper end face of the lower cladding; the microring resonator includes three annular waveguides with exactly the same size, and the three annular waveguides are evenly spaced and distributed on the first lower cladding in a sequence from front to back, and the lower end face of each annular waveguide is in contact with the upper end face of the lower cladding, and each The upper end faces of the three annular waveguides are 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 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 called the first annular waveguide, the second annular waveguide and the third annular waveguide from front to back, the first annular waveguide is located at the rear side of the bus waveguide, and There is a distance between the two, the third annular waveguide is located in front 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 annular 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 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.

[0007] Compared with the prior art, the present invention has the advantages that a microring resonator is formed by three annular waveguides of exactly the same size, the microring resonator has a simple structure, the three annular waveguides are evenly spaced and distributed on the first lower cladding layer in a sequence from front to back, the three annular waveguides are sequentially referred to as a first annular waveguide, a second annular waveguide and a third annular waveguide from front to back, a YIG seed layer is deposited on the upper end surface of the third annular 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 annular waveguide, the second annular waveguide and the third annular waveguide form a three-ring series structure, the third annular waveguide, the YIG seed layer and the magneto-optical material layer together form an annular magneto-optical waveguide, the bus waveguide and the adjacent part of the first annular waveguide form a first directional coupler, the first annular waveguide and the adjacent part of the second annular waveguide form a second directional coupler, and the second annular waveguide and the adjacent part of the annular magneto-optical waveguide form a third directional coupler; when a magnetic field is applied above the magneto-optical material layer in a direction pointing to the magneto-optical material, the magneto-optical material layer is directly connected to the magneto-optical material layer. When there is a magnetic field in the center line direction 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 taken as the forward light, and the light incident from the right end face is taken 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 to the first ring waveguide through the first directional coupler, and then transmitted in the first ring waveguide in the clockwise direction and the 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 light is transmitted in the second ring waveguide in a counterclockwise direction and a 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, the forward light and the reverse light are coupled to the magneto-optical waveguide through the third directional coupler, and then the light is transmitted in the magneto-optical waveguide in a clockwise direction and a counterclockwise direction, respectively. The forward light and the reverse light are then coupled to 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 the forward light and the reverse light are transmitted in different directions in the magneto-optical waveguide, the magneto-optical waveguide will present different resonant frequencies due to the non-reciprocal phase shift. One of the resonant frequencies of the magneto-optical waveguide is the same as the resonant frequencies of the first ring waveguide and the second ring waveguide, 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, that is, the reverse light, has a resonant peak in the spectrum, while the light in the direction corresponding to the other resonant frequency of the magneto-optical waveguide, that is, the resonant peak of the forward light will be split. This difference in the spectrum between the forward light and the reverse light leads to a smaller loss of the forward light and a larger optical power output, while the loss of the reverse light is larger and there is almost no optical power output, so the isolation of the reverse light is achieved, the isolation is larger, and the isolation bandwidth is wider. The simulation results show that the isolation of the present invention is greater than 40dB, and the isolation bandwidth can reach more than 14GHz. Therefore, the present invention has a large isolation bandwidth while having a small size and a high isolation ratio. ;

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

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

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

[0016] Figure 4 It is a forward light and reverse light spectrum diagram of the third-order singular point optical isolator based on 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 in 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 is further described in detail below with reference to the accompanying drawings.

[0020] Embodiment 1: Figures 1 to 3As shown, a third-order singular point optical isolator based on a microring resonator comprises a lower cladding 5, a bus waveguide 1 and a microring resonator. The bus waveguide 1 and the microring resonator are attached to the lower cladding 5 respectively. 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 at 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 annular waveguides with exactly the same size, and the three annular waveguides are evenly spaced and distributed on the first lower cladding 5 in a sequence from front to back, and the lower end face of each annular waveguide is in contact with the upper end face of the lower cladding 5, and the upper end face of each annular waveguide is in contact with the bus waveguide 1. The upper end faces of the bus waveguide 1 are located in the same plane, the central axes of the three annular waveguides are located in the same plane, and the plane makes the lower cladding 5 bilaterally symmetrical, the outer diameter of each annular waveguide is smaller than the length of the lower cladding 5, the difference between the outer diameter and the inner diameter of each annular waveguide is equal to the width of the bus waveguide 1, and the diameter of each annular waveguide is smaller than the length of the lower cladding 5; the three annular waveguides are sequentially called the first annular waveguide 2, the second annular waveguide 3 and the third annular waveguide 4 from front to back, the first annular waveguide 2 is located at the rear side of the bus waveguide 1, and the two are There is a distance between them, the third annular 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 annular 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 annular waveguide 4, and their inner diameters are equal to the inner diameter of the third annular waveguide 4, and their outer diameters are equal to the outer diameter of the third annular waveguide 4.

[0021] In this embodiment, the first annular waveguide 2, the second annular waveguide 3 and the third annular waveguide 4 constitute a three-ring series structure, the third annular waveguide 4, the YIG seed layer 6 and the magneto-optical material layer 7 together constitute an annular magneto-optical waveguide 8, the bus waveguide 1 and the adjacent part of the first annular waveguide 2 form a first directional coupler 9, the first annular waveguide 2 and the adjacent part of the second annular waveguide 3 form a second directional coupler 10, and the second annular waveguide 3 and the adjacent part of the annular 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 generate a non-reciprocal phase shift, and the light incident from the left end face of the bus waveguide 1 is used as the forward light, and the light incident from the right end face is used 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 to 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 to 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 to 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, and then coupled into the second ring waveguide 3, the first ring waveguide 2 and the bus waveguide 1 in sequence, and 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, and one of the magneto-optical waveguide 8 The resonant frequency is the same as the resonant frequency of the first annular waveguide 2 and the second annular 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 resonant 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 resonant peak of the forward light will be split. The difference in the spectrum between the forward light and the reverse light results in a smaller loss of the forward light and a larger optical power output, while a larger loss of the reverse light and almost no optical power output, thereby achieving isolation of the reverse light, with a larger isolation degree and a wider isolation bandwidth.

[0022] The third-order singular point optical isolator based on the microring resonator of this embodiment is realized by relying on the non-reciprocal phase shift generated by the magneto-optical material to which the magnetic field 12 is applied. Due to the existence of the non-reciprocal phase shift, the reverse light will show a propagation constant different from that of the forward light when it is transmitted in the magneto-optical waveguide 8. Therefore, the propagation constant of the reverse light will break the original working state in the optical isolator and show a frequency characteristic different from that of the forward light. The forward light shows a smaller loss in the spectrum, while the reverse light shows a larger loss in the spectrum, so isolation is achieved.

[0023] Embodiment 2: This embodiment is basically the same as Embodiment 1, except that: in this embodiment, the magneto-optical material is Ce:YIG, Bi:YIG, the material of the lower cladding 5 is SiO2, and the materials of the bus waveguide 1 and the three ring waveguides are all active materials or all 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] Embodiment 3: This embodiment is basically the same as Embodiment 2, except that: in this embodiment, an upper cladding layer is provided on the bus waveguide 1 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 waveguide. The material of the upper cladding layer is air or SiO2.

[0026] Embodiment 4: This embodiment is basically the same as Embodiment 3, except that: in this embodiment, the width of the bus waveguide 1, the first ring waveguide 2, the second ring waveguide 3 and the third ring waveguide 4 are all 1000nm, the thickness is all 400nm, the thickness of the YIG seed layer 6 is 30nm, the thickness of the magneto-optical material layer 7 is 150nm, the width of the YIG seed layer 6 and the magneto-optical material layer 7 are all 400nm, the inner diameter of the first ring waveguide 2, the second ring waveguide 3 and the magneto-optical waveguide 8 are all 72.8um, and the outer diameter is all 73.8um. ​​The materials of the bus waveguide 1, the first ring waveguide 2, the second ring waveguide 3 and the third ring waveguide 4 are all 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 in 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 produce 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 rate of the second directional coupler 10 is recorded as k, the coupling rate of the third directional coupler 11 is recorded as k, the bus waveguide 1 and the three ring waveguides of the optical isolator can be selected from active materials or passive materials according to different working requirements, and 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. According to the different materials selected and the different positions of applying the pump light, the third-order singular point optical isolator based on the microring resonator of the present invention can be designed into the following three types according to the needs of isolation bandwidth or insertion loss:

[0030] The first 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 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, In 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 light amplification, the split reverse light still has a large gain, thereby reducing the width that can achieve effective isolation, resulting in a minimum isolation bandwidth.

[0031] The 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 to make the second ring waveguide 3 neutral (no loss and no gain, that is, γ2 = 0). 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, so that it has the largest isolation bandwidth.

[0032] The third 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 passive materials: Si, SiN, lithium niobate, etc. No pump light is applied, and γ a =γ3+γ1-2γ2, In this design, compared with the first and second designs, since no pump light is applied, the optical isolator does not achieve light amplification, thus having the largest insertion loss. In addition, in this design, the optical power difference between the forward light and the reverse light that satisfies isolation is between the first and second designs above, so this design has a moderate isolation bandwidth.

[0033] For the first design, when light is transmitted in the forward direction, the natural frequencies of the first ring waveguide 2, the second ring waveguide 3, and the magneto-optical waveguide 8 are made the same through temperature tuning, and at this time, only one resonance peak appears in the spectrum. When light is transmitted in the reverse direction, the natural frequency of the magneto-optical waveguide 8 changes due to the non-reciprocal phase shift caused by the magnetic field, resulting in the splitting of the resonance peak. For the second design and the third design, when light is transmitted in the reverse direction, the natural frequencies of the first ring waveguide 2, the second ring waveguide 3, and the magneto-optical waveguide 8 are made the same through temperature tuning, and at this time, only one resonance peak appears in the spectrum. When light is transmitted in the forward direction, the natural frequency of the magneto-optical waveguide 8 changes due to the non-reciprocal phase shift caused by the magnetic field, resulting in the splitting of the resonance peak. For the above three designs, the splitting of the resonance peak is proportional to the cube root of the non-reciprocal phase shift, that is, the isolation bandwidth is also proportional to the cube root of the non-reciprocal phase shift. Therefore, when the non-reciprocal phase shift is small, the optical isolator can achieve an increase in the isolation bandwidth. Different designs will have different isolation bandwidths and different insertion losses. But in general, 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, which makes it difficult to apply them 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. From Figure 5 It can be seen from the figure that 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 In a smaller case, the optical isolator of the present invention can still have a larger isolation bandwidth.

[0035] In summary, the third-order singular point optical isolator based on microring resonator of the present invention constructs a 3rd-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 third-order singular point optical isolator based on microring resonator of the present invention is applied in integrated optics to 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 large-scale integration can be achieved.

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, 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-to-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-to-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 fit with the upper end face of the lower cladding; characterized in that The microring resonator comprises three annular waveguides of exactly the same size, the three annular waveguides are evenly spaced and distributed on the first lower cladding in a sequence from front to back, the lower end face of each annular waveguide is in a state of being in contact with the upper end face of the lower cladding, 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 sequentially referred to as the first annular waveguide from front to back. shaped waveguide, a second annular waveguide and a third annular waveguide, the first annular waveguide is located at the rear side of the bus waveguide, and there is a distance between the two, the third annular waveguide is located at 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 annular 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 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.

2. A 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 and 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.

3. A 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 also provided with an upper cladding layer which completely covers 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 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 1000nm and a thickness of 400nm, the thickness of the YIG seed layer is 30nm, the thickness of the magneto-optical material layer is 150nm, the width of the YIG seed layer and the magneto-optical material layer are both 400nm, the inner diameters of the first ring waveguide, the second ring waveguide and the third ring waveguide are all 72.8um, and the outer diameters are all 73.8um.

Images