Micro-ring modulator

Abstract

The present disclosure provides a micro-ring modulator, comprising: a first electrode having an opening formed thereon; the second electrode is arranged in the opening, and an annular space is defined by the second electrode and the first electrode; the annular waveguide is arranged in the annular space, the annular waveguide is prepared based on a lead zirconate titanate material, the annular waveguide comprises a first linear waveguide, the first linear waveguide is located on the inner side of the opening, and metal plasmon surface waves are formed between the first linear waveguide and the first electrode and between the first linear waveguide and the second electrode. According to the micro-ring modulator, the lead zirconate titanate with a high electro-optical coefficient is adopted, the high-efficiency modulation function of the whole modulator can be supported, meanwhile, the service life of photons in the annular resonant cavity is shortened by means of the high transmission loss characteristic of metal plasmon surface waves, and therefore the low Q value of the micro-ring modulator is achieved, the optical modulation bandwidth is improved, and the optical performance of the micro-ring modulator is improved. And finally, high-speed signal modulation is realized.

Description

Technical Field

[0001] The invention relates to the field of semiconductor optoelectronic devices, and in particular to a micro-ring modulator. Background Art

[0002] With the rapid development of artificial intelligence, IoT big data, cloud computing and other fields, the flow of information transmission and processing has also shown explosive growth. Traditional electrical interconnection can no longer meet the current huge data communication capacity and fast communication rate requirements. The development of photonic integration technology perfectly caters to the society's demand for large bandwidth, high speed and low power consumption. Large-scale optoelectronic integration and the realization of on-chip optical interconnection have become important breakthroughs for the further development of communication technology. Electro-optical modulators can modulate the intensity, phase and other characteristics of optical signals. It has also become an indispensable part of the entire optical communication network and is the key to optical interconnection.

[0003] Based on the complementary metal oxide semiconductor (CMOS) process platform, silicon photonic devices have significant advantages in large-scale optoelectronic integration. However, the central symmetric structure of silicon materials does not have a linear electro-optic coefficient, so it is necessary to use plasma dispersion effects for modulation. Due to the constraints of carrier migration rate and inherent capacitance, its modulation bandwidth is difficult to achieve a wide range. Lead zirconate titanate has excellent optical properties and a large electro-optic coefficient, and has great potential application value in the field of optoelectronic device manufacturing.

[0004] How to give full play to the excellent electro-optical properties of lead zirconate titanate to further improve the modulation efficiency and bandwidth of integrated optoelectronic modulation devices will become an extremely challenging task. Summary of the invention

[0005] In view of the above problems, the present invention provides a high-speed plasmon microring modulator based on lead zirconate titanate thin film material, which can achieve higher modulation bandwidth.

[0006] An embodiment of the present invention provides a micro-ring modulator, comprising: a first electrode, an opening formed on the first electrode; a second electrode, arranged in the opening, the second electrode and the first electrode forming an annular space; an annular waveguide, arranged in the annular space, the annular waveguide being prepared based on a lead zirconate titanate material, wherein the annular waveguide comprises a first straight waveguide, the first straight waveguide is located on the inner side of the opening, and a metal plasmon surface wave is formed between the first straight waveguide and the first electrode and the second electrode.

[0007] According to an embodiment of the present invention, the first linear waveguide is respectively attached to the first electrode and the second electrode to generate metal plasmon surface waves.

[0008] According to an embodiment of the present invention, the annular waveguide also includes a gradually varying width waveguide, which is connected to the first linear waveguide, and there is a gap between the gradually varying width waveguide and the first electrode and the second electrode, and the width of the gradually varying width waveguide gradually increases in a direction away from the first linear waveguide.

[0009] According to the embodiment of the present invention, the intervals between the gradually-varying-width waveguide and the first electrode and the second electrode gradually increase in a direction away from the first linear waveguide.

[0010] According to an embodiment of the present invention, the annular waveguide further comprises an arc waveguide, the arc waveguide is connected to the gradually varying width waveguide, and the width of the arc waveguide is equal to the maximum width of the gradually varying width waveguide.

[0011] According to an embodiment of the present invention, the ring waveguide includes a second straight waveguide, which is located outside the opening; the microring modulator also includes a straight waveguide, which is prepared based on lead zirconate titanate material, and the straight waveguide includes a third straight waveguide, which is coupled to the second straight waveguide.

[0012] According to an embodiment of the present invention, the micro-ring modulator further includes a ridge waveguide, and the second straight waveguide and the third straight waveguide are arranged in parallel on a coupling surface of the ridge waveguide.

[0013] According to an embodiment of the present invention, the straight waveguide further includes at least one curved waveguide, which is located on the ridge waveguide and connected to the third straight waveguide.

[0014] According to an embodiment of the present invention, the micro-ring modulator further includes: a buried oxide layer, and the ring waveguide, the first electrode and the second electrode are formed on the buried oxide layer.

[0015] According to an embodiment of the present invention, the micro-ring modulator further includes: a capping layer, which is disposed on the buried oxide layer, and the capping layer covers the ring waveguide, the first electrode, and the second electrode.

[0016] The embodiment of the present invention proposes a high-speed plasmon microring modulator based on lead zirconate titanate thin film material, wherein a lead zirconate titanate thin film waveguide is prepared by heterogeneous integrated growth on a silicon-on-insulator platform, and a low-Q value microring modulator based on the lead zirconate titanate thin film material is prepared by a complementary metal oxide semiconductor process. With the excellent optical properties of lead zirconate titanate and the high electro-optic coefficient of the lead zirconate titanate material, efficient modulation can be achieved without polymerizing, and the microring structure can realize high-density interconnection of optoelectronic devices and achieve larger-scale optoelectronic integration. At the same time, the high transmission loss characteristics of metal plasmon surface waves are utilized to reduce the photon lifetime in the ring resonator, thereby achieving a low Q value of the microring modulator, improving the optical bandwidth, and ultimately achieving high-rate modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0018] Figure 1 A schematic diagram of a planar structure of a micro-ring modulator according to an embodiment of the present invention is shown;

[0019] Figure 2 The three-dimensional structure and the plan view of the propagation part of the metal surface plasmon wave of the micro-ring modulator according to the embodiment of the present invention are schematically shown;

[0020] Figure 3 A partial cross-sectional view of a micro-ring modulator according to an embodiment of the present invention is schematically shown;

[0021] Figure 4 A schematic diagram of a simulated mode field diagram of a micro-ring resonant cavity mode conversion in a micro-ring modulator according to an embodiment of the present invention is shown;

[0022] Figure 5 Schematically shows the transmission spectrum of the coupled conversion of the propagation mode of the lead zirconate titanate waveguide in the micro-ring modulator according to the embodiment of the present invention;

[0023] Figure 6 The simulated transmission spectrum of the micro-ring modulator according to the embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0024] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] Figure 1The planar structure diagram of a micro-ring modulator according to an embodiment of the present invention is schematically shown.

[0028] like Figure 1 As shown, the micro-ring modulator may include a first electrode 31, a second electrode 32 and a ring waveguide 2. The first electrode 31 may be in a C-shaped shape with an opening formed thereon. The second electrode 32 is disposed in the C-shaped opening, and the second electrode 32 and the first electrode 31 form a ring space. The first electrode 31 and the second electrode 32 may be made of the same metal conductive material, which is not specifically limited in the present invention. One of the first electrode 31 and the second electrode 32 may be a positive electrode, and the other may be a negative electrode. The first electrode 31 and the second electrode 32 may be used to support the RF signal input of the micro-ring modulator.

[0029] The annular waveguide 2 is arranged in the annular space. The annular waveguide 2 can be prepared based on lead zirconate titanate material, and the lead zirconate titanate material has a high photoelectric coefficient. In some other embodiments, the annular waveguide 2 can also be prepared from some other materials with a high photoelectric coefficient. The annular waveguide 2 can also be called a micro-ring resonator. The racetrack micro-ring structure is adopted. The annular waveguide 2 can include a first straight waveguide 201. The first straight wave 201 is located on the inner side of the opening. A metal plasmon surface wave is formed between the first straight waveguide 201 and the first electrode 31 and the second electrode 32. The micro-ring modulator of this embodiment relies on the excellent optical properties of lead zirconate titanate. At the same time, the lead zirconate titanate material has a high electro-optical coefficient. It can achieve efficient modulation without polymer. The micro-ring structure can realize high-density optoelectronic device interconnection and achieve larger-scale optoelectronic integration. At the same time, the high transmission loss characteristics of the metal plasmon surface wave are used to reduce the photon lifetime in the annular resonator, thereby achieving a low Q value of the micro-ring modulator, improving the optical bandwidth, and finally achieving high-rate modulation.

[0030] Figure 2 The three-dimensional structure and the plan view of the metal surface plasmon wave propagation part of the micro-ring modulator according to the embodiment of the present invention are schematically shown.

[0031] like Figure 1 and Figure 2 As shown, the first straight waveguide 201 can be respectively attached to the first electrode 31 and the second electrode 32 to generate metal plasmon surface waves. The first straight waveguide 201 can be an extremely narrow waveguide with a height of 0.35 μm, and its width can be set to vary from 100 to 200 nm. The metal electrodes on both sides are closely attached to the lead zirconate titanate material, so that the metal surface plasmon waveguide structure at the inner side of the opening does not support the propagation of the lead zirconate titanate waveguide mode, and can use the high transmission loss characteristics of the metal plasmon surface wave to reduce the photon lifetime in the ring resonator, thereby achieving a low Q value of the microring modulator, improving the optical bandwidth, and finally achieving high-rate modulation.

[0032] like Figure 1 and Figure 2 As shown, the annular waveguide 2 may further include a gradually varying width waveguide 202, the gradually varying width waveguide 202 is connected to the first linear waveguide 201, there is a gap between the gradually varying width waveguide 202 and the first electrode 31 and the second electrode 32, and the width of the gradually varying width waveguide 202 gradually increases in a direction away from the first linear waveguide 201. As an example, the gradually varying width waveguide 202 may be a wedge-shaped waveguide. The two ends of the metal surface plasmon waveguide are gradually varying width waveguide structures, which can realize low-loss conversion of light propagation modes between waveguide modes and metal surface plasmon wave modes.

[0033] like Figure 1 and Figure 2 As shown, the spacing between the gradually changing width waveguide 202 and the first electrode 31 and the second electrode 32 gradually increases in the direction away from the first straight waveguide 201. For example, the spacing can vary linearly between 0 and 0.1 μm. For example, a certain angle can be set between the gradually changing width waveguide 202 and the first electrode 31 and the second electrode 32, and the vertex of the angle is the connection between the gradually changing width waveguide 202 and the first straight waveguide 201. The size of the angle can be flexibly related according to actual needs, and the present invention does not make specific limitations. As an example, the angle can be 15°.

[0034] like Figure 1 and Figure 2 As shown, the annular waveguide also includes an arc waveguide 203, and the arc waveguide 203 is connected to the gradually changing width waveguide 202, and the width of the arc waveguide 203 is equal to the maximum width of the gradually changing width waveguide 202. In this embodiment, the distance between the arc waveguide 203 and the electrodes 31 and 32 is relatively large, and the arc waveguide 203 supports the propagation of the lead zirconate titanate waveguide mode. At the gradually changing width waveguide 202, the light propagation mode begins to be converted between the lead zirconate titanate waveguide mode and the metal surface plasmon wave mode, until the light propagation of the metal surface plasmon wave mode is completely carried out in the first straight waveguide 201. Through the conversion of these three different propagation modes, the high-efficiency modulation function of the entire modulator can be supported, and the high transmission loss characteristics of the metal plasmon surface wave can be utilized to reduce the photon lifetime in the annular resonant cavity, thereby achieving a low Q value of the micro-ring modulator, improving the optical modulation bandwidth, and finally achieving high-speed signal modulation.

[0035] Please continue reading Figure 1, the ring waveguide 2 also includes a second straight waveguide 204, and the second straight waveguide 204 is located outside the opening. The micro-ring modulator can also include a straight waveguide 1, which can also be prepared based on lead zirconate titanate material. The straight waveguide 1 includes a third straight waveguide 11, and the third straight waveguide 11 is coupled to the second straight waveguide 204. In the micro-ring modulator, the straight waveguide 1 can be used as an input and output end to couple the light in the straight waveguide 1 to the ring waveguide 2, modulate it in the ring waveguide 2, and then return to the coupling area, that is, coupled to the straight waveguide 1 and then output.

[0036] like Figure 1 As shown, the micro-ring modulator may further include a ridge waveguide 101, and the second linear waveguide 204 and the third linear waveguide 11 are arranged in parallel on the coupling surface of the ridge waveguide 101 to improve the coupling efficiency. The ridge waveguide 101 may be made of lead zirconate titanate material.

[0037] like Figure 1 As shown, the straight waveguide 1 also includes curved waveguides 12 and 13, which are located on the ridge waveguide 101 and connected to the third straight waveguide 11. In this embodiment, the straight waveguide 1 is a combination of a straight waveguide and a curved waveguide, which ensures that the length of the optical coupling region between the straight waveguide and the microring resonator is controllable, and the coupling length matches the light loss in the microring resonator to achieve a critical coupling condition.

[0038] Please continue reading Figure 1 The ring waveguide 2, the first electrode 31 and the second electrode 32 may be formed on the buried oxide layer 4, and the buried oxide layer 4 may be disposed on the substrate 5 (see Figure 3 ). In some embodiments, the micro-ring modulator may further include a capping layer (not shown in the figure), which is disposed on the buried oxide layer 4, and the capping layer covers the ring waveguide 2, the first electrode 31 and the second electrode 32 to ensure the stability of the micro-ring modulator. The buried oxide layer 4 and the capping layer may be made of silicon dioxide material. The growth and preparation process of the straight waveguide 1, the ring waveguide 2 and the electrodes 31 and 32 is compatible with the complementary metal oxide semiconductor (CMOS) process, and all structures can be grown with silicon material as the substrate and silicon dioxide as the upper layer of the buried oxide layer 4.

[0039] Figure 3 A partial cross-sectional diagram of a micro-ring modulator according to an embodiment of the present invention is schematically shown.

[0040] like Figure 2 and Figure 3As shown, they are schematic diagrams of the cross-sections A-A', B-B', and C-C' of the propagation section of the metal surface plasmon wave. As an example, the waveguide height of the straight waveguide 1 can be 0.35μm, and the width can be 0.8μm to support single-mode transmission of O-band wavelength optical signals. The waveguide height of the ring waveguide 2 can be equal to that of the straight waveguide 1, which can be 0.35μm, and its width varies with different functional requirements. The second straight waveguide height of the ring waveguide 2 close to one end of the straight waveguide 1 can be 0.35μm and the width can be 0.8μm to meet the single-mode mode matching of the optical coupling; the two sections of the arc waveguide have a height of 0.35μm and a width of 0.8μm, supporting single-mode transmission. The radius size of the arc waveguide 203 and the length of the straight waveguide can be set according to actual needs, and the present invention does not make specific limitations. The coupling spacing between the straight waveguide 1 and the ring waveguide 2 can be 190nm to ensure a good coupling effect. The first straight waveguide 201 can be an extremely narrow waveguide with a height of 0.35 μm, and its width can be set to vary from 100 to 200 nm. The first straight waveguide 201 does not support the propagation of the lead zirconate titanate waveguide mode, but only supports the propagation of the metal surface plasmon wave mode. Electrodes 31 and 32 are distributed at both ends of the annular waveguide 2. In the lead zirconate titanate waveguide mode propagation area, i.e., the arc waveguide 203, the distance between electrodes 31 and 32 and the waveguide can be 1 μm. In the width gradient waveguide 202 area, the distance between electrodes 31 and 32 and the waveguide can vary linearly between 0 and 0.1 μm. The metal surface plasmon waveguide, that is, the spacing between the metal electrode and the lead zirconate titanate waveguide in the first straight waveguide 201 area is 0. The thickness of electrodes 31 and 32 can be 0.35 μm, and can also be flexibly designed according to actual needs. The etching depth in the ridge waveguide 101 area can be 150 nm, and the thickness of the plate can be 200 nm to meet the single-mode mode matching of optical coupling and ensure the length required for coupling. It should be noted that the above dimensions of the micro-ring modulator are only an example and do not constitute a limitation on the technical content of the present invention. Those skilled in the art can adjust and reasonably set them according to actual conditions.

[0041] Figure 4 The simulated mode field diagram of the micro-ring resonant cavity mode conversion in the micro-ring modulator according to the embodiment of the present invention is schematically shown. Figure 5 The transmission spectrum of the coupled conversion of the propagation mode of the lead zirconate titanate waveguide in the micro-ring modulator according to the embodiment of the present invention is schematically shown. Figure 6 The simulated transmission spectrum of the micro-ring modulator according to the embodiment of the present invention is schematically shown.

[0042] like Figure 4As shown, the mode conversion simulation mode field diagrams at the sections A-A', B-B', and C-C' of the propagation of the metal surface plasmon wave are shown respectively. The loss of the transverse electric (TE) mode at the sections A-A', B-B', and C-C' is 2.586e-5 dB / cm, 1070.1 dB / cm, and 6990.1 dB / cm, respectively. It can be seen that through the structural design of the embodiment of the present invention, a better mode loss effect can be achieved.

[0043] like Figure 5 As shown, in the coupled conversion transmission spectrum, the horizontal axis represents the wavelength, and the vertical axis represents the mode conversion rate. It can be seen from the figure that for different wavelengths, the micro-ring modulator of the embodiment of the present invention can realize low-loss conversion of the light propagation mode between the waveguide mode and the metal surface plasmon wave mode.

[0044] like Figure 6 As shown in FIG. 1 , the simulation experiment result without the silicon dioxide cap layer is obtained, and the static transmission spectrum of the micro-ring modulator can be obtained, and its Q value is about 606. It can be seen that through the structural design of the micro-ring modulator of this embodiment, the low Q value of the micro-ring modulator can be achieved, and the optical modulation bandwidth can be improved.

[0045] In summary, the embodiments of the present invention propose a high-speed plasmon microring modulator based on lead zirconate titanate thin film material, and prepare a lead zirconate titanate thin film waveguide by heterogeneous integrated growth on a silicon-on-insulator platform. A low-Q value microring modulator based on lead zirconate titanate thin film material is prepared by a complementary metal oxide semiconductor process. With the excellent optical properties of lead zirconate titanate and the high electro-optic coefficient of lead zirconate titanate material, efficient modulation can be achieved without polymer. The microring structure can realize high-density interconnection of optoelectronic devices and achieve larger-scale optoelectronic integration. At the same time, the high transmission loss characteristics of metal plasmon surface waves are utilized to reduce the photon lifetime in the ring resonator, thereby achieving a low Q value of the microring modulator, improving the optical bandwidth, and ultimately achieving high-rate modulation.

[0046] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present invention may be combined or coupled in various ways, even if such combinations or couplings are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention may be combined and / or coupled in various ways without departing from the spirit and teachings of the present invention. All of these combinations and / or couplings fall within the scope of the present invention.

[0047] Although the present invention has been shown and described with reference to specific exemplary embodiments of the present invention, it will be appreciated by those skilled in the art that various changes in form and detail may be made to the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments.

Claims

1. A micro-ring modulator, characterized in that: include: a first electrode, wherein an opening is formed on the first electrode; A second electrode is disposed in the opening, wherein the second electrode and the first electrode form an annular space; A ring waveguide is arranged in the ring space, and the ring waveguide is prepared based on lead zirconate titanate material, wherein the ring waveguide includes a first straight waveguide, the first straight waveguide is located on the inner side of the opening, and a metal plasmon surface wave is formed between the first straight waveguide and the first electrode and the second electrode.

2. The micro-ring modulator according to claim 1, characterized in that: The first linear waveguide is respectively attached to the first electrode and the second electrode to generate the metal plasmon surface wave.

3. The micro-ring modulator according to claim 1, characterized in that: The annular waveguide also includes a gradually varying width waveguide, which is connected to the first linear waveguide, and there is a gap between the gradually varying width waveguide and the first electrode and the second electrode. The width of the gradually varying width waveguide gradually increases in a direction away from the first linear waveguide.

4. The micro-ring modulator according to claim 3, characterized in that: The intervals between the gradually-varying-width waveguide and the first electrode and the second electrode gradually increase in a direction away from the first linear waveguide.

5. The micro-ring modulator according to claim 4, characterized in that: The annular waveguide further includes an arc waveguide, which is connected to the gradually varying width waveguide, and the width of the arc waveguide is equal to the maximum width of the gradually varying width waveguide.

6. The micro-ring modulator according to any one of claims 1 to 5, characterized in that: The annular waveguide includes a second straight waveguide, and the second straight waveguide is located outside the opening; The micro-ring modulator further includes a through waveguide, which is prepared based on lead zirconate titanate material. The through waveguide includes a third straight waveguide, and the third straight waveguide is coupled to the second straight waveguide.

7. The micro-ring modulator according to claim 6, characterized in that: The micro-ring modulator further comprises a ridge waveguide, and the second straight waveguide and the third straight waveguide are arranged in parallel on a coupling surface of the ridge waveguide.

8. The micro-ring modulator according to claim 6, characterized in that: The through waveguide further includes at least one curved waveguide, which is located on the ridge waveguide and connected to the third straight waveguide.

9. The micro-ring modulator according to claim 1, characterized in that: The micro-ring modulator further comprises: A buried oxide layer, the annular waveguide, the first electrode and the second electrode are formed on the buried oxide layer.

10. The micro-ring modulator according to claim 9, characterized in that: The micro-ring modulator further comprises: A capping layer is disposed on the buried oxide layer, and the capping layer covers the annular waveguide, the first electrode and the second electrode.

Images