Optical modulator, optical signal modulation method, and electronic device

Abstract

The invention discloses an optical modulator, an optical signal modulation method and electronic equipment, and belongs to the technical field of silicon-based optoelectronic integrated chips. The optical modulator comprises a single-mode bus waveguide, the input end of the single-mode bus waveguide is used for receiving incident light in a first mode, and the output end of the single-mode bus waveguide is used for outputting output light in the first mode; the front resonant cavity waveguide is provided with an antisymmetric grating structure and is used for exciting the incident light in the first mode into forward light in a second mode and converting the forward light in the second mode and backward light in a third mode; and the rear resonant cavity waveguide is provided with an antisymmetric grating structure, is cascaded with the front resonant cavity waveguide and is used for influencing the resonance distribution state of the optical signals transmitted in the front resonant cavity waveguide by adjusting the phase of the optical signals transmitted in the rear resonant cavity waveguide so as to realize the modulation of the output light of the single-mode bus waveguide.

Description

Technical Field

[0001] This application relates to the field of silicon-based optoelectronic integrated chip technology, and in particular to an optical modulator, an optical signal modulation method, and an electronic device. Background Technology

[0002] With the advent of the big data era, the demand for high-speed, high-capacity optical communication networks is increasing daily. In optical communication systems, the optical modulator is a key component, and its performance directly determines the transmission rate and distance of the entire system. Silicon-based optoelectronic integration technology is widely used in next-generation optical communication systems due to its advantages such as compatibility with existing complementary metal-oxide-semiconductor (CMOS) processes, high integration density, and low power consumption.

[0003] Silicon-based modulators play a crucial role in next-generation optical communication systems, serving as key components for realizing high-speed, high-capacity optical communication networks. Their small size and high integration facilitate the construction of compact optical circuit systems. With the increasing demand for interconnection within and between data centers, there is an urgent need for highly integrated optical interconnect systems, a requirement that silicon-based modulators can meet. Silicon-based modulators achieve high-speed modulation through mechanisms such as carrier injection or depletion, supporting transmission rates of hundreds of gigabits per second (Gbps) and even terabits per second (Tbps), effectively alleviating current bandwidth bottlenecks and meeting the ever-growing data transmission demands. Furthermore, silicon-based modulators have low power consumption; when highly integrated with electronic devices, they can build energy-efficient optoelectronic integrated systems, contributing to the realization of green and environmentally friendly next-generation communication networks. As a key component in optical circuits, the performance of silicon-based modulators directly determines the transmission capacity of the entire optical communication system.

[0004] In related technologies, silicon-based optical modulators mainly fall into two categories: Mach-Zehnder modulators and microring modulators. Mach-Zehnder modulators modulate optical signals by changing the relative phase difference between the two waveguide arms, offering a wide modulation range, but they occupy a large area and are difficult to integrate. Microring modulators utilize the resonant effect of a microring cavity to modulate optical signals; they are small in size and easy to integrate, but their modulation bandwidth is limited by the free path length range of the microring.

[0005] Therefore, how to improve the modulation bandwidth of micro-ring modulators is a technical problem that needs to be solved in related technologies. Summary of the Invention

[0006] This application provides an optical modulator, an optical signal modulation method, and an electronic device to improve the modulation bandwidth of the optical modulator.

[0007] In a first aspect, an optical modulator is provided, comprising: a single-mode bus waveguide, wherein the input end of the single-mode bus waveguide is used to receive incident light of a first mode, and the output end is used to output output light of the first mode; a front resonant cavity waveguide having an antisymmetric grating structure, used to excite the incident light of the first mode into forward light of a second mode, and to perform conversion processing on the forward light of the second mode and the backward light of a third mode; and a rear resonant cavity waveguide having an antisymmetric grating structure, cascaded with the front resonant cavity waveguide, used to influence the resonant distribution state of the optical signal transmitted in the front resonant cavity waveguide by adjusting the phase of the optical signal transmitted in the rear resonant cavity waveguide, thereby achieving modulation of the output light of the single-mode bus waveguide.

[0008] In a second aspect, an optical signal modulation method is provided, applied to the optical modulator described in the first aspect. The method includes: receiving incident light of a first mode through the input terminal of a single-mode bus waveguide; exciting the incident light of the first mode into forward light of a second mode through a front resonant cavity waveguide; and performing conversion processing on the forward light of the second mode and the backward light of a third mode; and adjusting the phase of the optical signal transmitted in the rear resonant cavity waveguide through the rear resonant cavity waveguide to affect the phase resonance distribution state of the optical signal transmitted in the front resonant cavity waveguide, so as to achieve modulation of the output light of the single-mode bus waveguide.

[0009] Thirdly, an electronic device is provided that includes the optical modulator described in the first aspect.

[0010] The optical modulator provided in this application includes a single-mode bus waveguide, a front resonant cavity waveguide with an antisymmetric grating structure, and a rear resonant cavity waveguide with an antisymmetric grating structure. The output light of the single-mode bus waveguide is modulated by the front and rear resonant cavity waveguides. Because the front and rear resonant cavity waveguides have antisymmetric grating structures, a high quality factor resonant cavity can be formed, thereby obtaining a modulator with a high extinction ratio. Furthermore, the front and rear resonant cavity waveguides are cascaded. By adjusting the phase of the optical signal transmitted in the rear resonant cavity waveguide, the resonant distribution state of the optical signal transmitted in the front resonant cavity waveguide is affected, thereby achieving modulation of the output light of the single-mode bus waveguide. This allows for an effective trade-off between wide bandwidth and high extinction ratio by adjusting the coupling strength and phase relationship between the front and rear resonant cavity waveguides, thus expanding the modulation bandwidth.

[0011] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0012] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0013] Figure 1 A schematic diagram of the structure of an optical modulator provided in an exemplary embodiment of this application is shown; Figure 2 A schematic diagram of the structure of an optical modulator provided in another exemplary embodiment of this application is shown; Figure 3 A schematic diagram of the structure of an optical modulator provided in yet another exemplary embodiment of this application is shown; Figure 4a A schematic diagram of the simulation results for the carrier concentration distribution of a horizontal PN junction under 0V bias is shown. Figure 4b A schematic diagram of the simulation results for a horizontal PN junction is shown. Figure 4c A schematic diagram of the simulation results for the carrier concentration distribution of an S-type PN junction under 0V bias is shown. Figure 4d A schematic diagram of the simulation results for an S-type PN junction is shown. Figure 5a A schematic diagram of an antisymmetric grating structure in an exemplary embodiment is shown; Figure 5b A schematic diagram of the transmission and reflection spectrum simulation results of an antisymmetric grating structure in an exemplary embodiment is shown; Figure 5c A schematic diagram of an input TEO mode optical signal of an antisymmetric grating structure in an exemplary embodiment is shown; Figure 5d A schematic diagram of the TE1 mode optical signal reflected by an antisymmetric grating structure in an exemplary embodiment is shown. Figure 6a A schematic diagram of the output transmission spectrum of an optical modulator in an exemplary embodiment is shown; Figure 6b A schematic diagram of the electro-optic modulation response of an optical modulator in an exemplary embodiment is shown; Figure 7 A flowchart of an exemplary embodiment of the present application is shown. Detailed Implementation

[0014] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0015] Figure 1A schematic diagram of the structure of an optical modulator provided in an exemplary embodiment of this application is shown, as follows: Figure 1 As shown, the optical modulator mainly includes: a single-mode bus waveguide 10, a front resonant cavity waveguide 20, and a rear resonant cavity waveguide 30. The input end of the single-mode bus waveguide 10 is used to receive incident light of the first mode, and the output end is used to output the output light of the first mode. The front resonant cavity waveguide 20 has an antisymmetric grating structure and is used to excite the incident light of the first mode into forward light of the second mode, and to perform conversion processing on the forward light of the second mode and the backward light of the third mode. The rear resonant cavity waveguide 30 has an antisymmetric grating structure and is cascaded with the front resonant cavity waveguide 20. The rear resonant cavity waveguide 30 is used to influence the resonant distribution state of the optical signal transmitted in the front resonant cavity waveguide 20 by adjusting the phase of the optical signal transmitted in the rear resonant cavity waveguide 30, thereby achieving modulation of the output light of the single-mode bus waveguide 10.

[0016] The optical modulator provided in the embodiments of this application consists of a single-mode bus waveguide and two cascaded resonant cavity waveguides with antisymmetric grating structures. By utilizing the antisymmetric grating structure, a resonant cavity with a high quality factor can be formed, thereby obtaining a modulator with a high extinction ratio. Furthermore, by adopting a cascaded dual-cavity structure and adjusting the coupling strength and phase relationship, an effective trade-off between wide bandwidth and high extinction ratio can be achieved, thus expanding the modulation bandwidth.

[0017] In some embodiments, such as Figure 2 As shown, the front resonant cavity waveguide consists of a front cavity mirror 21, a first phase-shifting waveguide 22, and the first part of an inter-cavity coupler 40. The front cavity mirror 21 is an anti-symmetric grating structure used to reflect the backward light of the third mode into the forward light of the second mode. The first phase-shifting waveguide 22 is connected in series with the front cavity mirror 21 and is used to excite the input light of the first mode into the forward light of the second mode. The inter-cavity coupler 40 is used to couple the front resonant cavity waveguide 20 and the rear resonant cavity waveguide 30. The inter-cavity coupler 40 is used to transmit a portion of the forward light of the second mode forward to the rear resonant cavity waveguide 30, and to convert another portion of the forward light of the second mode into the backward light of the third mode. The backward light of the third mode is then transmitted to the front cavity mirror 21 via the first phase-shifting waveguide 22. The first phase-shifting waveguide 22 is also used to couple the forward light of the second mode into the output light of the first mode output from the output end of the single-mode total waveguide 10.

[0018] In some embodiments, such as Figure 2As shown, the rear resonant cavity waveguide 30 consists of the second part of the intercavity coupler 40, the second phase-shifting waveguide 31, and the rear cavity reflector 32. The second phase-shifting waveguide 31 is used to adjust the phase of the forward light of the second mode and transmit the adjusted forward light of the second mode to the rear cavity reflector 32. The rear cavity reflector 32 is an antisymmetric grating structure used to reflect the forward light of the second mode into the backward light of the third mode, and transmit the backward light of the third mode to the front cavity reflector 21 through the second phase-shifting waveguide 31 and the intercavity coupler 40.

[0019] In some embodiments, such as Figure 1 and Figure 2 As shown, the intercavity coupler 40 can be a waveguide employing an antisymmetric grating structure. In these embodiments, the coupling strength between the two resonant cavities can be adjusted by regulating the number of periods of the intercavity coupler 40. Optionally, the transmittance of the intercavity coupler 40 can be determined based on the coupling strength between the front resonant cavity 20 and the rear resonant cavity 30; that is, the coupling strength between the front resonant cavity 20 and the rear resonant cavity 30 is controlled by the reflectivity of the intercavity coupler 40. In these embodiments, by setting the intercavity coupler 40 as an antisymmetric grating structure, the coupling strength between the two resonant cavities can be controlled by controlling the reflectivity of the intercavity coupler 40.

[0020] In the above embodiment, a phase-shifting waveguide is also added to the two resonant cavities. The phase relationship between the two resonant cavities can be adjusted by the phase-shifting waveguide, thereby controlling the extinction ratio of the optical modulator.

[0021] By using the optical modulator in the above embodiments, the reflectivity, coupling strength, and phase relationship can be precisely controlled by optimizing the parameters of the antisymmetric grating structure (such as period, sidewall ripple width, etc.), coupling region length, and phase-shifting waveguide length, thereby obtaining modulator performance with high quality factor, high extinction ratio, and wide bandwidth.

[0022] In some embodiments, to prevent the third-mode optical signal from back-coupled into the bus waveguide, the absolute value of the difference in refractive index between the second-mode optical signal and the third-mode optical signal can be greater than a second threshold. The second threshold can be set according to the specific application.

[0023] In some embodiments of this application, the first mode can be TE. b0 The second mode can be TE. g1 The third mode can be TE. g0 Mode. In these embodiments, the single-mode bus waveguide 10 supports TE. b0 The mode, with the first phase-shifting waveguide 22 and the second phase-shifting waveguide 31 supporting TE g0 and TE g1 Pattern; where TE b0 and TEg1 The effective refractive indices of the modes are equal; the antisymmetric grating structure has mode conversion function, and the input TE... g0 The pattern light, reflected as TE g1 Pattern light.

[0024] exist Figure 2 In the optical modulator shown, the input TE b0 The mode light is first coupled into the first phase-shifting waveguide 22 of the front resonant cavity waveguide 20, exciting the TE. g1 The forward light of the mode (i.e., the forward-transmitted optical signal), this TE g1 The forward-propagating light of the mode continues to propagate forward, passing through the intercavity coupler 40 (i.e., the second antisymmetric grating), where a portion of the reflection mode is converted into TE. g0 The backlight of the mode (i.e., the optical signal transmitted backward), another part of the transmission is still in TE g1 The forward light of the mode enters the resonant cavity waveguide 30; the transmitted TE... g1 The forward propagation of the mode light encounters the rear cavity mirror 32 (i.e., the third antisymmetric grating) and is partially reflected, converting the mode into TE. g0 The backward propagation of the mode's light may partially transmit and overflow into the resonant cavity waveguide 30; the aforementioned reflected TE g0 The backward propagation of the mode light encounters the front cavity mirror 21 (i.e., the first antisymmetric grating), and part of the reflection mode is converted into TE. g1 The forward propagation of the mode's light may partially transmit and overflow from the front resonant cavity waveguide 20. Therefore, in this structure, TE... g1 The optical signal in the mode always propagates forward, TE g0 The optical signal of the mode always propagates backward, and both modes exist simultaneously in the two resonant cavity waveguides, forming resonance; due to TE g0 and TE g1 The effective refractive indexes of the modes differ significantly, therefore the back-propagating light will not couple into the bus waveguide in the reverse direction.

[0025] The light field may leak in the first and third antisymmetric grating structures. Therefore, in some embodiments, the absolute value of the difference between the reflectivity of the front cavity mirror 21 and the rear cavity mirror 32 and 1 is less than a first threshold. That is, the reflectivity of the front cavity mirror 21 and the rear cavity mirror 32 is designed to be close to 1.

[0026] In some embodiments, such as Figure 3 As shown, a PN junction 33 can also be integrated into the second phase-shifting waveguide 31. In these embodiments, the optical signal transmitted in the rear resonant cavity waveguide is modulated through the carrier dispersion effect, thereby achieving modulation of the output light intensity.

[0027] In the above embodiment, by adding a PN junction 33 to the second phase-shifting waveguide 31 and applying a reverse bias voltage to the PN junction 33, phase modulation of light can be achieved using the plasma dispersion effect. When different reverse bias voltages are applied, the carrier concentration in the silicon waveguide changes, thereby changing the effective refractive index of the waveguide, which in turn causes a change in the phase of light propagating in the waveguide, thus achieving phase modulation of light.

[0028] Optionally, PN junction 33 can be a horizontal PN junction or an S-type PN junction. Figure 4a and Figure 4b The simulation results for the carrier concentration distribution of a horizontal PN junction under 0V bias are shown. For a horizontal PN junction, the junction capacitance gradually decreases with increasing reverse bias, while the corresponding electrical bandwidth gradually increases.

[0029] Figure 4c and Figure 4d The simulation results of carrier concentration distribution in an S-type PN junction under 0V bias are shown. Unlike a horizontal PN junction, the P-region and N-region of the S-type PN junction are not parallel in the lateral direction, but rather S-shaped. This structural design increases the junction interface area between the P-region and N-region, thereby enhancing the interaction between the optical field and carriers and improving modulation efficiency. The junction capacitance of the S-type PN junction is generally higher than that of the horizontal PN junction, and the decrease with increasing bias voltage is also greater, but the corresponding potential for improving electrical bandwidth is also greater. Therefore, when designing a modulator, a balance can be struck between junction capacitance (which determines electrical bandwidth) and modulation efficiency. The S-type PN junction can sacrifice some electrical bandwidth for higher modulation efficiency; while the horizontal PN junction has a relatively high electrical bandwidth, but relatively low modulation efficiency.

[0030] In some embodiments, the waveguide of the aforementioned antisymmetric grating structure has antisymmetric serrated protrusions on both sides, the distribution period of which satisfies the Bragg reflection condition. Optionally, the waveguide of the antisymmetric grating structure is formed by periodically arranging waveguides of at least two different widths, which can support two different modes. By designing the period of the grating and the width of the sidewall corrugations, effective coupling between the two modes can be achieved, so that one mode undergoes strong Bragg reflection when propagating in the grating, while the other mode can transmit freely. Utilizing this characteristic, the antisymmetric grating can serve as a high-reflectivity resonant cavity mirror, forming a resonant cavity with a high quality factor.

[0031] Figure 5a This illustration shows a schematic diagram of an antisymmetric grating in an exemplary embodiment of this application. Figure 5b A graph of the transmission and reflection spectra in an antisymmetric grating in this exemplary embodiment is shown, while Figure 5cThis is a schematic diagram of a TEO mode optical signal input into an antisymmetric grating structure. Figure 5d This is a schematic diagram illustrating the TE1 mode optical signal output after the TE0 mode optical signal is reflected by an anti-symmetrical grating structure. Figures 5a to 5d As shown, grooves can be periodically etched on both sides of the silicon waveguide to form a corrugated sidewall structure. The period of this corrugated sidewall structure is designed to satisfy the Bragg condition near the operating wavelength, thus forming an antisymmetric grating. When the wavelength of the incident light satisfies the phase-matching condition, orthogonal modes are excited within the waveguide of the antisymmetric grating structure. The input is the TE0 mode, whose optical field is symmetrically distributed at the center of the waveguide. After reflection by the grating, the antisymmetric TE1 mode is excited. By optimizing parameters such as waveguide width, corrugation width, and period, the coupling strength between the two modes can be controlled. The transmission and reflection spectra of the antisymmetric grating obtained from the Finite Difference Time Domain (FDTD) simulation show that the transmittance is close to 0 and the reflectance reaches its maximum value at the center wavelength of 1549.63 nm.

[0032] In some embodiments, the front resonant cavity waveguide 10, the single-mode bus waveguide 20, and the rear resonant cavity waveguide 30 can be silicon waveguides.

[0033] Optionally, the width of the front cavity reflector 21, the rear cavity reflector 32, the first phase-shifting waveguide 22, and the second phase-shifting waveguide 31 can be in the range of 0.6-0.8 micrometers, and the height can be 0.22 micrometers.

[0034] Figure 6a and Figure 6b Simulation results of the transmission spectrum and electro-optic bandwidth of the optical modulator in an exemplary embodiment of this application are shown. Under a 5V reverse bias, its 3dB modulation electro-optic bandwidth can exceed 60GHz. This high electro-optic bandwidth is mainly achieved due to two factors: dual-cavity coupling reduces the intracavity photon lifetime, thereby increasing the optical bandwidth of the modulator; and the antisymmetric grating-based resonant cavity has a very small mode volume, reducing the PN junction capacitance and improving the electrical bandwidth. Furthermore, the short PN junction significantly reduces drive power consumption. By adjusting the resonant wavelengths of the two resonant cavities and their coupling strength, the resonant extinction ratio can be flexibly controlled, thus achieving a relatively large modulation depth.

[0035] Therefore, the optical modulator provided in this application combines an antisymmetric grating and a cascaded dual cavity, taking into account the three aspects of electro-optic bandwidth, driving power consumption and modulation depth, and can achieve high-performance optical modulation.

[0036] Figure 7This application shows a schematic flowchart of an exemplary embodiment of an optical signal modulation method, which can be applied to the aforementioned optical modulator, such as... Figure 7 As shown, the method mainly includes the following steps.

[0037] S701 receives incident light of the first mode through the input terminal of the single-mode bus waveguide; S702, through the front resonant cavity waveguide, excites the incident light of the first mode into the forward light of the second mode, and performs conversion processing on the forward light of the second mode and the backward light of the third mode. S703, by adjusting the phase of the optical signal transmitted in the rear resonant cavity waveguide, the resonant distribution state of the optical signal transmitted in the front resonant cavity waveguide is affected, so as to achieve modulation of the output light of the single-mode bus waveguide.

[0038] The method provided in this application embodiment allows for the modulation of light using an optical modulator with a resonant cavity waveguide having an antisymmetric grating structure, thereby achieving an effective trade-off between wide bandwidth and high extinction ratio and expanding the modulation bandwidth.

[0039] In some embodiments, exciting the incident light of the first mode into forward light of the second mode through a front resonant cavity waveguide, and converting the forward light of the second mode and the backward light of the third mode may include the following steps: Step 1: The input light of the first mode is excited into the forward light of the second mode through the first phase-shifting waveguide; Step 2: A portion of the forward light of the second mode is transmitted forward to the rear resonant cavity waveguide through the intercavity coupler, and the other portion of the forward light of the second mode is converted into backward light of the third mode. The backward light of the third mode is then transmitted to the front cavity mirror through the first phase-shifting waveguide. Step 3: The rearward light of the third mode is reflected into the forward light of the second mode by the front cavity mirror; Step 4: The forward light of the second mode is coupled into the output light of the first mode from the output terminal through the first phase-shifting waveguide.

[0040] In some embodiments, adjusting the phase of the optical signal transmitted in the rear resonant cavity waveguide to affect the phase of the optical signal transmitted in the front resonant cavity waveguide includes: Step 1: Adjust the phase of the forward light of the second mode through the second phase-shifting waveguide, and transmit the adjusted forward light of the second mode to the rear cavity mirror; Step 2: The forward light of the second mode is reflected into backward light of the third mode by the rear cavity mirror, and the backward light of the second mode is transmitted to the front cavity mirror through the second phase-shifting waveguide and the intercavity coupler.

[0041] The technical solution provided in this application embodiment enables efficient optical modulation through precise phase control, thereby improving the modulation depth and extinction ratio of the device. The flexible phase adjustment capabilities of the first and second phase shifters allow the modulator to be adjusted under different operating conditions, thus adapting to various application requirements. Furthermore, by optimizing the design of the phase shifters, phase errors between resonant cavities can be reduced, increasing the Q value of the resonant cavities and ultimately improving the overall performance of the modulator.

[0042] This application also provides an electronic device that may include the aforementioned optical modulator. This electronic device can serve as an optical signal transmission device and is used in scenarios such as data centers.

[0043] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0044] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. An optical modulator, comprising: The application relates to a single-mode bus waveguide, a front resonant cavity waveguide with an antisymmetric grating structure, a back resonant cavity waveguide with an antisymmetric grating structure, and a cavity inter-coupler. The single-mode bus waveguide is used for receiving incident light of a first mode and outputting output light of the first mode. The front resonant cavity waveguide is used for exciting the incident light of the first mode into forward light of a second mode and converting the forward light of the second mode and backward light of a third mode. The back resonant cavity waveguide is cascaded with the front resonant cavity waveguide and is used for adjusting the phase of the light signal transmitted in the back resonant cavity waveguide to affect the resonance distribution state of the light signal transmitted in the front resonant cavity waveguide, thereby realizing the modulation of the output light of the single-mode bus waveguide.

2. The optical modulator of claim 1, wherein, The front resonant cavity waveguide is composed of a front cavity mirror, a first phase shift waveguide and a first part of the cavity inter-coupler. The front cavity mirror is an antisymmetric grating structure and is used for reflecting the backward light of the third mode into the forward light of the second mode. The first phase shift waveguide is connected in series with the front cavity mirror and is used for exciting the input light of the first mode into the forward light of the second mode. The cavity inter-coupler is used for coupling the front resonant cavity waveguide and the back resonant cavity waveguide. The first phase shift waveguide is also used for coupling the forward light of the second mode into the output light of the first mode output from the output end.

3. The optical modulator of claim 2, wherein, The back resonant cavity waveguide is composed of a second part of the cavity inter-coupler, a second phase shift waveguide and a back cavity mirror. The second phase shift waveguide is used for adjusting the phase of the forward light of the second mode and transmitting the adjusted forward light of the second mode to the back cavity mirror. The back cavity mirror is an antisymmetric grating structure and is used for reflecting the forward light of the second mode into the backward light of the third mode and transmitting the backward light of the third mode to the front cavity mirror through the second phase shift waveguide and the cavity inter-coupler.

4. The optical modulator of claim 3, wherein, The cavity inter-coupler is a waveguide with an antisymmetric grating structure.

5. The optical modulator of claim 4, wherein, The transmittance of the cavity inter-coupler is determined based on the coupling strength of the front resonant cavity and the back resonant cavity.

6. The optical modulator of claim 3, wherein, The second phase shift waveguide is integrated with a PN junction.

7. The optical modulator of claim 6, wherein, The PN junction includes a horizontal PN junction or an S-shaped PN junction.

8. The optical modulator of any one of claims 1 to 7, wherein, The waveguide with the antisymmetric grating structure has sawtooth-shaped protrusions with an antisymmetric distribution on two sides, and the distribution period of the sawtooth-shaped protrusions with the antisymmetric distribution satisfies the Bragg reflection condition.

9. The optical modulator of claim 8, wherein, The waveguide with the antisymmetric grating structure is periodically arranged by at least two waveguides with different widths.

10. The optical modulator of claim 3, wherein, The absolute value of the difference between the reflectivity of the front cavity mirror and the back cavity mirror and 1 is less than a first threshold value.

11. The optical modulator of any one of claims 1 to 7, wherein, The front resonant cavity waveguide, the single-mode bus waveguide and the back resonant cavity waveguide include silicon waveguides.

12. The optical modulator of claim 3, wherein, The front cavity mirror, the back cavity mirror, the first phase shift waveguide and the second phase shift waveguide have a width ranging from 0.6 to 0.8 microns and a height of 0.22 microns.

13. The optical modulator of claim 2 or 3, wherein, An absolute value of a difference between the refractive index of the second mode of light signal and the third mode of light signal is greater than a second threshold value.

14. A method of modulating an optical signal, applied to the optical modulator of any one of claims 1 to 13, characterized in that, The method comprises: receiving, by an input end of a single-mode bus waveguide, incident light of a first mode; exciting, by a front resonant cavity waveguide, the incident light of the first mode into forward light of a second mode, and converting the forward light of the second mode and backward light of a third mode; adjusting, by the back resonant cavity waveguide, a phase of light signals transmitted in the back resonant cavity waveguide to affect a resonance distribution state of light signals transmitted in the front resonant cavity waveguide, to realize modulation of output light of the single-mode bus waveguide.

15. The method of claim 14, wherein, exciting, by a front resonant cavity waveguide, the incident light of the first mode into forward light of a second mode, and converting the forward light of the second mode and backward light of a third mode, comprises: exciting, by a first phase shift waveguide, input light of a first mode into forward light of a second mode; transmitting, by an inter-cavity coupler, a part of the forward light of the second mode forwardly to the back resonant cavity waveguide, and converting another part of the forward light of the second mode into backward light of a third mode, and transmitting, by the first phase shift waveguide, the backward light of the third mode to a front cavity mirror; reflecting, by the front cavity mirror, the backward light of the third mode into forward light of the second mode; coupling, by the first phase shift waveguide, the forward light of the second mode into output light of the first mode output from the output end.

16. The method of claim 15, wherein, adjusting, by the back resonant cavity waveguide, a phase of light signals transmitted in the back resonant cavity waveguide to affect a phase of light signals transmitted in the front resonant cavity waveguide, comprises: adjusting, by a second phase shift waveguide, a phase of forward light of a second mode, and transmitting the adjusted forward light of the second mode to a back cavity mirror; reflecting, by the back cavity mirror, the forward light of the second mode into backward light of a third mode, and transmitting the backward light of the second mode to the front cavity mirror via the second phase shift waveguide and the inter-cavity coupler.

17. An electronic device, comprising: An optical modulator comprising any one of claims 1 to 13.

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