High-Speed Plasmonic Micro-Ring Modulator Based on Lead Zirconate Titanate Thin Film Material

Abstract

The present disclosure provides a high-speed plasmonic microring modulator based on a lead zirconate titanate thin film material, comprising: a first electrode with an opening formed thereon; a second electrode disposed within the opening, and the second electrode and the first electrode enclose an annular space; an annular waveguide disposed within the annular space, the annular waveguide being prepared based on a lead zirconate titanate material and adopting a racetrack microring structure, the annular waveguide including a first straight waveguide located inside the opening, and a metal plasmonic surface wave is formed between the first straight waveguide and the first electrode and the second electrode. The microring modulator of the present invention uses lead zirconate titanate with a high electro-optic coefficient, which can support the high-efficiency modulation function of the entire modulator. At the same time, by utilizing the high transmission loss characteristic of the metal plasmonic surface wave, the photon lifetime in the annular resonator is reduced, thereby realizing a low Q value of the microring modulator, increasing the optical modulation bandwidth, and finally realizing high-rate signal modulation.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor optoelectronic devices, and in particular to a high-speed plasmon microring modulator based on lead zirconate titanate thin film material. 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 ring waveguide further includes a width-gradual waveguide, the width-gradual waveguide is connected to the first straight waveguide, there is a gap between the width-gradual waveguide and the first electrode and the second electrode, and the width of the width-gradual waveguide gradually increases along the direction away from the first straight waveguide.

[0009] According to an embodiment of the present invention, the gaps between the width-gradual waveguide and the first electrode and the second electrode gradually increase along the direction away from the first straight waveguide.

[0010] According to an embodiment of the present invention, the ring waveguide further includes an arc waveguide, the arc waveguide is connected to the width-gradual waveguide, and the width of the arc waveguide is equal to the maximum width of the width-gradual waveguide.

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

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

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

[0014] According to an embodiment of the present invention, the microring 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 microring modulator further includes: a capping layer disposed on the buried oxide layer, and the capping layer covers the ring waveguide, the first electrode and the second electrode.

[0016] An embodiment of the present invention provides a high-speed plasmonic microring modulator based on a lead zirconate titanate thin film material. A lead zirconate titanate thin film waveguide is heteroepitaxially grown on a silicon-on-insulator platform, and a low-Q microring modulator based on a lead zirconate titanate thin film material is fabricated using complementary metal oxide semiconductor processes. Relying on the excellent optical properties of lead zirconate titanate, and lead zirconate titanate material has a high electro-optic coefficient, high-efficiency modulation can be achieved without using polymer. The microring structure can achieve high-density optoelectronic device interconnection, realizing larger-scale optoelectronic integration. At the same time, by using the high transmission loss characteristics of metal surface plasmons, the photon lifetime in the ring resonator is reduced, thereby achieving a low-Q value of the microring modulator, increasing the optical bandwidth, and finally achieving high-speed modulation. Description of the Drawings

[0017] Through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, the above and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0018] Figure 1 Schematically shows a planar structure diagram of a microring modulator according to an embodiment of the present invention;

[0019] Figure 2 Schematically shows a three-dimensional structure and a planar schematic diagram of the surface plasmon wave propagation part of a microring modulator according to an embodiment of the present invention;

[0020] Figure 3 Schematically shows a partial cross-sectional schematic diagram of a microring modulator according to an embodiment of the present invention;

[0021] Figure 4 Schematically shows a simulation mode field diagram of the mode conversion in a microring resonator of a microring modulator according to an embodiment of the present invention;

[0022] Figure 5 Schematically shows the propagation mode coupling conversion transmission spectrum of a lead zirconate titanate waveguide in a microring modulator according to an embodiment of the present invention;

[0023] Figure 6 Schematically shows the simulation transmission spectrum of a microring modulator according to an embodiment of the present invention. Detailed implementation manners

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

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

[0026] All terms used herein (including technical and scientific terms) 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 1A planar structure diagram of a microring modulator according to an embodiment of the present invention is schematically shown.

[0028] As Figure 1 shown, the microring modulator may include a first electrode 31, a second electrode 32, and a ring waveguide 2. The first electrode 31 may have a C-shaped configuration with an opening formed thereon. The second electrode 32 is disposed within the C-shaped opening, and the second electrode 32 and the first electrode 31 enclose an annular space. The first electrode 31 and the second electrode 32 may be made of the same metal conductive material, and the present invention does not make specific limitations. One of the first electrode 31 and the second electrode 32 may be a positive electrode, and the other is a negative electrode. The first electrode 31 and the second electrode 32 may be used to support the input of radio frequency signals of the microring modulator.

[0029] The ring waveguide 2 is disposed within the annular space. The ring waveguide 2 may be prepared based on a lead zirconate titanate material, which has a high electro-optical coefficient. In some other embodiments, the ring waveguide 2 may also be made of some other materials with high electro-optical coefficients. The ring waveguide 2 may also be referred to as a microring resonator and adopts a racetrack microring structure. The ring waveguide 2 may include a first straight waveguide 201. The first straight waveguide 201 is located inside the opening, and a metal surface plasmon wave is formed between the first straight waveguide 201 and the first electrode 31 and the second electrode 32. The microring 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-optic coefficient and can achieve efficient modulation without the need for polymer. The microring structure can realize the interconnection of high-density optoelectronic devices, achieve a larger-scale optoelectronic integration, and at the same time utilize the high transmission loss characteristics of the metal surface plasmon wave to reduce the photon lifetime in the ring resonator, thereby realizing a low Q value of the microring modulator, increasing the optical bandwidth, and finally realizing high-speed modulation.

[0030] Figure 2 A three-dimensional structure and a planar schematic diagram of the metal surface plasmon wave propagation part of the microring modulator according to an embodiment of the present invention are schematically shown.

[0031] As Figure 1 and Figure 2 shown, the first straight waveguide 201 may be respectively attached to the first electrode 31 and the second electrode 32 to generate a metal surface plasmon wave. The first straight waveguide 201 may be an extremely narrow waveguide with a height of 0.35 μm, and its width may be set to be between 100 - 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 inside the opening does not support the propagation of the lead zirconate titanate waveguide mode, and can utilize the high transmission loss characteristics of the metal surface plasmon wave to reduce the photon lifetime in the ring resonator, thereby realizing a low Q value of the microring modulator, increasing the optical bandwidth, and finally realizing high-speed modulation.

[0032] As Figure 1 and Figure 2 shown, the ring waveguide 2 may further include a width-graded waveguide 202. The width-graded waveguide 202 is connected to the first straight waveguide 201. There is a gap between the width-graded waveguide 202 and the first electrode 31 and the second electrode 32. The width of the width-graded waveguide 202 gradually increases along the direction away from the first straight waveguide 201. As an example, the width-graded waveguide 202 may be a wedge-shaped waveguide. Both ends of the metal surface plasmon waveguide are width-graded waveguide structures, which can achieve low-loss conversion of the optical propagation mode between the waveguide mode and the metal surface plasmon mode.

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

[0034] As Figure 1 and Figure 2 shown, the ring waveguide further includes an arc waveguide 203. The arc waveguide 203 is connected to the width-graded waveguide 202. The width of the arc waveguide 203 is equal to the maximum width of the width-graded waveguide 202. In this embodiment, the gap between the arc waveguide 203 and the electrodes 31, 32 is relatively large. The arc waveguide 203 supports the propagation of the lead zirconate titanate waveguide mode. At the width-graded waveguide 202, the conversion of the optical propagation mode between the lead zirconate titanate waveguide mode and the metal surface plasmon mode starts, and until the first straight waveguide 201, the optical propagation of the metal surface plasmon mode is completely carried out. Through the conversion of these three different propagation modes, it can not only support the high-efficiency modulation function of the entire modulator, but also utilize the high transmission loss characteristics of the metal surface plasmon wave to reduce the photon lifetime in the ring resonator, thereby realizing the low Q value of the micro-ring modulator, improving the optical modulation bandwidth, and finally realizing high-speed signal modulation.

[0035] Please continue to refer to Figure 1, the ring waveguide 2 further includes a second straight waveguide 204, and the second straight waveguide 204 is located outside the opening. The microring modulator may further include a through waveguide 1, and the through waveguide 1 may also be prepared based on lead zirconate titanate material. The through waveguide 1 includes a third straight waveguide 11, and the third straight waveguide 11 is mutually coupled with the second straight waveguide 204. In the microring modulator, the through waveguide 1 can serve as an input / output end, couple the light in the through waveguide 1 into the ring waveguide 2, modulate it in the ring waveguide 2 and then return to the coupling region, that is, output after being coupled to the through waveguide 1.

[0036] As Figure 1 shown, the microring modulator may further include a ridge waveguide 101. The second straight waveguide 204 and the third straight waveguide 11 are arranged in parallel on the coupling surface of the ridge waveguide 101 to improve the coupling efficiency. The ridge waveguide 101 can be prepared with lead zirconate titanate material.

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

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

[0039] Figure 3 Schematically shows a partial cross-sectional view of a microring modulator according to an embodiment of the present invention.

[0040] As Figure 2 and Figure 3As shown, they are respectively schematic diagrams of partial cross-sections A-A', B-B', and C-C' of the propagation of surface plasmon polariton waves on the metal surface. As an example, the waveguide height of the straight waveguide 1 can be 0.35 μm, and the width can be 0.8 μm to support single-mode transmission of optical signals with O-band wavelengths. The waveguide height of the ring waveguide 2 can be equal to that of the straight waveguide 1, which can be 0.35 μm, and its width varies according to different functional requirements. The height of the second straight waveguide at one end of the ring waveguide 2 close to the straight waveguide 1 can be 0.35 μm, and the width is 0.8 μm to meet the single-mode mode matching of optical coupling; the height of the two arc waveguides is 0.35 μm, and the width is 0.8 μm, 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 distance between the straight waveguide 1 and the ring waveguide 2 can be 190 nm 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 nm 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 surface plasmon polariton wave mode. The electrodes 31 and 32 are distributed at both ends of the ring waveguide 2. In the region of the lead zirconate titanate waveguide mode propagation, that is, at the arc waveguide 203, the distance between the electrodes 31 and 32 and the waveguide can be 1 μm. In the region of the width-gradual waveguide 202, the distance between the electrodes 31 and 32 and the waveguide can vary linearly between 0 and 0.1 μm. For the surface plasmon polariton waveguide, that is, the distance between the metal electrode and the lead zirconate titanate waveguide in the region of the first straight waveguide 201 is 0. The thickness of the 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 region can be 150 nm, and the thickness of the flat 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 given for the micro-ring modulator are only an example and do not constitute a limitation to the technical content of the present invention. Those skilled in the art can make adjustments and reasonable settings according to the actual situation.

[0041] Figure 4 Schematically shows the simulation mode field diagram of the micro-ring resonator mode conversion in the micro-ring modulator according to an embodiment of the present invention. Figure 5 Schematically shows the coupling conversion transmission spectrum of the lead zirconate titanate waveguide propagation mode in the micro-ring modulator according to an embodiment of the present invention. Figure 6 Schematically shows the simulation transmission spectrum of the micro-ring modulator according to an embodiment of the present invention.

[0042] As Figure 4As shown, the simulation mode field diagrams at the mode conversion parts of cross-sections A-A', B-B', and C-C' of the surface plasmon polariton wave propagation on the metal surface are respectively shown. The losses of the transverse electric (TE) mode at cross-sections A-A', B-B', and C-C' are 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] As Figure 5 shown, in the coupling conversion transmission spectrum, the abscissa represents the wavelength and the ordinate 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 achieve low-loss conversion of the optical propagation mode between the waveguide mode and the surface plasmon polariton wave mode.

[0044] As Figure 6 shown, for the simulation experiment results without the silica cover layer, the static transmission spectrum of the micro-ring modulator can be obtained, and its Q value is approximately 606. It can be seen that through the structural design of the micro-ring modulator of this embodiment, a low Q value of the micro-ring modulator can be achieved, and the optical modulation bandwidth can be improved.

[0045] In summary, the embodiment of the present invention proposes a high-speed plasmonic micro-ring modulator based on lead zirconate titanate thin film material. The lead zirconate titanate thin film waveguide is heteroepitaxially grown on the silicon-on-insulator platform, and a low-Q micro-ring modulator based on lead zirconate titanate thin film material is fabricated using complementary metal oxide semiconductor process. Relying on the excellent optical properties of lead zirconate titanate, and at the same time, the lead zirconate titanate material has a high electro-optic coefficient, and high-efficiency modulation can be achieved without using polymer. The micro-ring structure can realize the interconnection of high-density optoelectronic devices, achieve larger-scale optoelectronic integration, and at the same time, utilize the high transmission loss characteristics of the surface wave of metal plasmon to reduce the photon lifetime in the ring resonator, thereby realizing the low Q value of the micro-ring modulator, improving the optical bandwidth, and finally realizing high-speed modulation.

[0046] Those skilled in the art can understand that the features described in the various embodiments of the present invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations 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, those skilled in the art should understand that various changes in form and detail can 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 embodiments.

Claims

1. A high-speed plasmon microring modulator based on lead zirconate titanate thin film material, 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, the ring waveguide is made based on lead zirconate titanate material and adopts a racetrack micro-ring structure, and the ring waveguide includes: A first linear waveguide is located inside the opening, and the first linear waveguide is respectively attached to the first electrode and the second electrode to form a metal plasmon surface wave between the first linear waveguide and the first electrode and the second electrode; a gradually varying width waveguide connected to the first linear waveguide, wherein a gap exists 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; an arc waveguide connected to the gradually varying width waveguide, wherein the width of the arc waveguide is equal to the maximum width of the gradually varying width waveguide, and 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; A second linear waveguide, located outside the opening; The micro-ring modulator further comprises: A straight-through waveguide is prepared based on lead zirconate titanate material, and the straight-through waveguide includes a third straight waveguide, and the third straight waveguide is coupled to the second straight waveguide.

2. The micro-ring modulator according to claim 1, 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.

3. The micro-ring modulator according to claim 2, 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.

4. 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.

5. The micro-ring modulator according to claim 4, 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.

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