Composite multimode waveguide structure
By combining a composite multimode waveguide structure with plasmonic units and dielectric waveguides, the contradiction between optical field confinement and transmission distance in plasmonic waveguides is resolved, achieving low-loss and multimode transmission and improving the integration and performance of photonic devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-23
- Publication Date
- 2026-04-03
AI Technical Summary
Existing plasmonic waveguides struggle to balance optical field confinement and transmission distance, and suffer from high transmission loss, requiring complex structural designs to support multi-mode transmission.
A composite multimode waveguide structure is adopted, which combines plasmonic units and dielectric waveguides to optimize the structural design to achieve low loss, strong optical field confinement and multimode transmission. This includes the use of a combination of metallic materials and high refractive index semiconductor materials, designed as rectangular, trapezoidal or parabolic dielectric waveguides, and the addition of a low refractive index support layer in the substrate layer.
It achieves low-loss optical signal transmission, supports multimode transmission, improves the integration and performance of photonic devices, reduces manufacturing difficulty, and is suitable for high-density photonic integrated chips.
Smart Images
Figure CN224081844U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of optoelectronic device technology, and in particular to a composite multimode waveguide structure. Background Technology
[0002] Surface plasmon waveguides, as an emerging photonic structure, have attracted widespread attention in recent years in fields such as nanophotonics, biomedical imaging, and optical communication. Surface plasmons are surface waves propagating at the interface between a metal and a dielectric with free electrons. Due to their subwavelength characteristics and ability to overcome the diffraction limit, they can significantly improve the localization of the optical field and reduce the size of photonic devices. However, despite the significant advantages of plasmon waveguides in optical field confinement, they still face many challenges in practical applications. While existing plasmon waveguides can achieve subwavelength-scale optical field confinement, they suffer from high transmission loss, and there is a trade-off between mode confinement capability and transmission distance, making it difficult to balance strong confinement with long-distance transmission. Furthermore, they require relatively complex structural designs to support the transmission of multiple modes. Given the limitations of traditional waveguide technology, the development of a novel plasmon waveguide structure that combines low loss, strong optical field confinement capability, and multi-mode transmission functionality is particularly urgent. Utility Model Content
[0003] In view of this, the present invention provides a composite multimode waveguide structure that at least partially solves the problems existing in the prior art.
[0004] This utility model embodiment provides a composite multimode waveguide structure, including:
[0005] Plasmon units are made of metallic materials or materials with negative real dielectric functions. The plasmon units are realized in the form of continuous thin films, discrete nanostructures or periodic arrays. The structural features of the plasmon units include nanoparticles, nanowires, nanopore arrays or gradient structures.
[0006] A dielectric waveguide, wherein the dielectric waveguide is made of a semiconductor material with a high refractive index, and the dielectric waveguide is designed as one of a strip waveguide, a ridge waveguide or a slot waveguide, and the cross-sectional shape of the dielectric waveguide is one of a rectangle, a trapezoid or a parabola, and is allowed to contain longitudinally tapered or periodically modulated structures;
[0007] The substrate layer, located below the plasmonic unit and the dielectric waveguide, includes at least one low-refractive-index support layer. The material system of the low-refractive-index support layer is one of oxide material, nitride material, fluoride material or composite substrate structure. The substrate is one of planar substrate, patterned substrate or flexible substrate. The substrate includes a stress adjustment layer and a thermal expansion matching layer.
[0008] According to a specific implementation of this utility model, the plasmon unit is a symmetrical slit waveguide composed of two parallel gold sheets. The dielectric waveguide is a silicon waveguide, which is located in the middle of the gold slit waveguide and maintains a certain distance from the gold layers on both sides, forming two symmetrical slits on both sides. The slits and the area above the waveguide are filled with an organic polymer.
[0009] According to a specific implementation of this utility model, the working wavelength of the composite multimode waveguide structure is 1550nm and the waveguide thickness is 220nm.
[0010] According to a specific implementation of this utility model, parameter S is defined as the ratio of the width of the Si nanowire to the total width of the composite multimode waveguide. When the value of S reaches 0.7, the composite multimode waveguide structure exhibits multiple modes.
[0011] According to a specific implementation of this utility model, the composite multimode waveguide structure can simultaneously support both TE0 and TE1 modes of transmission.
[0012] According to a specific implementation of this utility model, the loss of the composite multimode waveguide structure gradually increases with the increase of parameter S, and the overall transmission loss of the composite multimode waveguide structure is as low as 0.08dB / μm.
[0013] According to a specific implementation of this utility model, the field interaction factor Γ is defined. slot,x for:
[0014]
[0015] in Let x be the x-component of the electric field perpendicular to the propagation direction within the gapped waveguide. and These represent the electric field strength and magnetic field strength at the transmission cross section, respectively.
[0016] The field interaction factor decreases as S increases, while it increases as the electrode spacing increases.
[0017] According to a specific implementation of this utility model, when the total waveguide width W = 1 μm and S = 0.85, the propagation loss of the composite multimode waveguide structure is 0.08 dB / μm and the field interaction factor is 0.48.
[0018] This invention proposes a plasmonic composite multimode waveguide structure that employs a hybrid approach combining plasma and dielectric waveguides to achieve the coexistence and interaction of photonic and plasmonic modes. Optimized structural design effectively improves propagation loss and achieves subwavelength scale confinement of light waves. Simultaneously, optimized waveguide width enables the structure to support multimode transmission. This design effectively resolves the contradictions between plasma devices and silicon photonics in terms of mode freedom, loss, and process compatibility, providing a new paradigm for next-generation multifunctional optoelectronic integrated chips. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 A composite multimode waveguide structure diagram provided for an embodiment of this utility model;
[0021] Figure 2 Another composite multimode waveguide structure diagram provided in this embodiment of the present invention;
[0022] Figure 3 The dispersion curve of the composite multimode waveguide with waveguide width;
[0023] Figure 4 The waveguide mode distribution is shown when the total waveguide width W is 800 nm and S is 0.9.
[0024] Figure 5 The curves show the effect of different structural parameters on the waveguide structure loss.
[0025] Figure 6 Let Γ be the field interaction factor Γ of the composite multimode waveguide structure under different electrode spacings as the parameter S changes from 0.85 to 0.95. slot,x The changing pattern. Detailed Implementation
[0026] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.
[0027] The composite multimode waveguide structure proposed in this utility model is as follows: Figure 1 As shown, the structure consists of the following functional layers:
[0028] Plasmon Unit 1: The plasmon unit can be a metallic material such as gold, silver, copper, metal alloys, or alkali metals, or other materials with a negative real dielectric function, such as conductive oxides (ITO and ZnO, etc.), graphene, and other materials with plasmon properties. The unit can be implemented in the form of continuous thin films, discrete nanostructures, or periodic arrays, and structural features include, but are not limited to, nanoparticles, nanowires, nanopore arrays, or gradient structure designs.
[0029] Dielectric waveguide 2: The dielectric waveguide can be a semiconductor material with a high refractive index, such as silicon, germanium, or gallium nitride, or other microstructure materials. The waveguide layer can be designed as a strip waveguide, ridge waveguide, slit waveguide, or other geometric configurations, and its cross-sectional shape includes, but is not limited to, rectangular, trapezoidal, and parabolic shapes, and may include longitudinally gradient or periodic modulation structures.
[0030] Substrate layer 3: Located below the plasmonic unit and the dielectric waveguide as a substrate. The substrate layer comprises at least one low-refractive-index support layer, the material system of which includes: oxide materials: silicon dioxide, aluminum oxide, tantalum oxide, etc.; nitride materials: silicon nitride, aluminum nitride, etc.; fluoride materials: calcium fluoride, magnesium fluoride, etc.; composite substrate structures: heterogeneous integrated substrates such as SOI (silicon-on-insulator) and GOI (germanium-on-insulator). The substrate can be designed as a planar substrate, a patterned substrate, or a flexible substrate, and is allowed to include functional interlayers such as stress-adjusting layers and thermal expansion matching layers. The claims of this utility model not only cover... Figure 2 The specific examples of composite multimode waveguide structures shown also broadly cover various variants and improved structures derived from this basic structure. These improved structures include, but are not limited to, adjustments and optimizations to the material selection, geometry, dimensional parameters, and interlayer combination methods of each functional layer of the waveguide. Figure 1 The invention showcases several improved structures. Furthermore, this invention also protects composite structures that further integrate or combine other functional elements, materials, or technologies onto the basic structure, as well as specific design modifications made to adapt to different application scenarios.
[0031] In one implementation, the plasmonic unit consists of two parallel gold sheets forming a symmetrical slit waveguide. A silicon waveguide, located in the middle of the gold slit waveguide, is positioned at a certain distance from the two gold layers, forming two symmetrical slits on either side. An organic polymer is then filled into the slits and above the waveguide. This invention selects 1550nm as the operating wavelength, and the waveguide thickness, based on the standard SOI waveguide measurement, is set to 220nm. The specific structure is as follows... Figure 2 As shown.
[0032] To delve into the impact of variations in composite multimode waveguide structural parameters on structural performance, this invention comprehensively considers multiple key structural parameters, including the width of the silicon waveguide, electrode spacing, and waveguide thickness. Given that composite multimode waveguides are influenced by both photonic and plasmonic modes, to more accurately analyze the combined effects of silicon waveguide width and electrode spacing on structural performance, this invention introduces a new parameter definition: S, representing the ratio of the width of the Si nanowire to the total width of the composite multimode waveguide, i.e., S = W. Si / W.
[0033] Figure 3 The dispersion curves of the composite multimode waveguide with varying waveguide widths are shown. From the figures, we can observe that when the S-value reaches 0.7, multiple modes begin to appear in structures with different electrode spacings. The composite multimode waveguide structure of this invention can simultaneously support both TE0 and TE1 modes. Figure 4 The waveguide mode distribution is shown when the total waveguide width W is 800 nm and S is 0.9.
[0034] Furthermore, the total width W of the fixed composite multimode waveguide of this invention is 800 nm, 900 nm, and 1 μm, respectively, and the S value is varied from 0.85 to 0.95. The influence of different structural parameters on the waveguide structure loss is systematically demonstrated, and the relevant results are as follows: Figure 5 and Figure 6 As shown. From Figure 5 The analysis results show that the loss of the composite multimode waveguide gradually increases with the increase of parameter S. This phenomenon is due to the change in the optical field distribution within the slit as the width of the intermediate silicon waveguide increases; the optical field gradually shifts from near the silicon waveguide sidewall to the metal sidewall. This change in optical field distribution leads to an increase in loss. However, despite the increase in loss, the overall transmission loss of the composite multimode waveguide remains at a low level. Specifically, its lowest loss value is 0.08 dB / μm, which is better than that of the traditional plasmonic slot waveguide (0.5 dB / μm). This indicates that the composite multimode waveguide achieves an effective balance and optimization of loss performance compared to traditional waveguide structures, possessing the dual advantages of low loss and high performance.
[0035] To quantify the interaction between the optical carrier, the modulated electrical signal, and the electro-optical material, a field interaction factor Γ is defined. slot,x (Field interaction factor) is:
[0036]
[0037] in Let x be the x-component of the electric field perpendicular to the propagation direction within the gapped waveguide. and These represent the electric field strength and magnetic field strength of the transmission cross section, respectively.
[0038] Figure 6 The field interaction factor Γ of the composite multimode waveguide structure with different electrode spacings is shown as the parameter S varies from 0.85 to 0.95. slot,x The variation law is shown. The results indicate that the field interaction factor gradually decreases with increasing S, while it increases significantly with increasing electrode spacing. For a waveguide with a total width W = 1 μm, the overall range of the field interaction factor is between 0.37 and 0.48, while the field interaction factor Γ of the traditional silicon void waveguide structure is much higher. slot,x The overall value is less than 0.225, indicating that composite multimode waveguides have significant advantages in enhancing the interaction between optical and electric fields, thus providing strong support for achieving efficient optoelectronic device integration. According to... Figure 5 and Figure 6 Simulation results show that, with a total waveguide width W = 1 μm and S = 0.85, the propagation loss of the composite multimode waveguide is only 0.08 dB / μm, while the field interaction factor can reach 0.48. This indicates that the structure can achieve subwavelength scale confinement of optical waves under low propagation loss conditions and can simultaneously support both TE0 and TE1 modes of transmission.
[0039] The beneficial effects of this composite multimode waveguide include:
[0040] 1) Low loss and high efficiency transmission: This invention achieves low-loss optical signal transmission by cleverly integrating a dielectric waveguide into a plasmonic slit waveguide. Its loss value is significantly lower than that of traditional plasmonic waveguides, thereby greatly improving the transmission efficiency and providing strong support for long-distance, high-bandwidth optical transmission.
[0041] 2) Balancing Loss and Confinement: This waveguide structure effectively confines the optical field at the subwavelength scale while maintaining low transmission loss, successfully overcoming the inherent trade-off between loss and optical field confinement in existing technologies. This characteristic provides new possibilities for high-density photonic integration, significantly improving the integration density and performance of photonic devices;
[0042] 3) Multi-mode transmission: The waveguide structure of this invention supports multi-mode transmission, significantly improving data transmission capacity and providing broader scope and greater flexibility for applications in optical sensing, optical computing, and optical communication. By optimizing the waveguide's geometric parameters and material properties, efficient transmission in multiple modes is achieved, meeting the needs of high-bandwidth applications.
[0043] 4) Low processing difficulty: The use of a wider slit reduces the complexity of the manufacturing process and the requirements for the precision of photolithography and etching.
[0044] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.
Claims
1. A composite multi-mode waveguide structure, characterized by, It comprises: Plasmonic unit, which is composed of metal material or material with negative real part dielectric function, and is realized in the form of continuous film, discrete nanostructure or periodic array, and the structural features of plasmonic unit include nanoparticles, nanowires, nanopore array or gradient structure; Dielectric waveguide, which is composed of semiconductor material with high refractive index, and is designed as one of strip waveguide, ridge waveguide or slot waveguide, and the cross-sectional shape of dielectric waveguide is one of rectangle, trapezoid and parabola, and it allows to contain longitudinal gradient or periodic modulation structure; Substrate layer, which is located below the plasmonic unit and dielectric waveguide, and contains at least one low refractive index support layer, and the material system of the low refractive index support layer is one of oxide material, nitride material, fluoride material or composite substrate structure, and the substrate is one of planar substrate, patterned substrate or flexible substrate, and the substrate contains stress adjustment layer and thermal expansion matching layer.
2. The composite multi-mode waveguide structure of claim 1, wherein: The plasmonic unit is composed of two parallel gold sheets to form a symmetrical slot waveguide, the dielectric waveguide is a silicon waveguide, the silicon waveguide is located in the middle of the slot waveguide and keeps a certain distance with the two side gold layers, forming two symmetrical slots on both sides, and the slots and the upper part of the waveguide are filled with organic polymer.
3. The composite multi-mode waveguide structure of claim 2, wherein: The working wavelength of the composite multimode waveguide structure is 1550 nm, and the waveguide thickness is 220 nm.
4. The composite multi-mode waveguide structure of claim 3, wherein: The defined parameter S is the ratio of the width of Si nanowire to the total width of the composite multimode waveguide, when the value of S reaches 0.7, the composite multimode waveguide structure appears multiple modes.
5. The composite multi-mode waveguide structure of claim 4, wherein: The composite multimode waveguide structure can support TE0 and TE1 mode transmission at the same time.
6. The composite multi-mode waveguide structure of claim 5, wherein: The loss of the composite multimode waveguide structure gradually increases with the increase of parameter S, and the overall transmission loss of the composite multimode waveguide structure is 0.08 dB / μm.
7. The composite multi-mode waveguide structure of claim 6, wherein: Defining field interaction factor is: wherein is the x-component of the electric field in the gap waveguide perpendicular to the direction of transmission, and are the electric and magnetic field intensities, respectively, of the transmission cross-section; The field interaction factor decreases with the increase of S, and increases with the increase of the distance between electrodes.
8. The composite multi-mode waveguide structure of claim 7, wherein: When the total width of the waveguide W=1μm and S=0.85, the propagation loss of the composite multimode waveguide structure is 0.08 dB / μm, and the field interaction factor is 0.48.