A semiconductor waveguide and SPP waveguide coupler

Abstract

This invention relates to a semiconductor waveguide-SPP waveguide coupler, belonging to the field of integrated nanophotonic chip technology. It includes a first coupler and a second coupler. The first coupler comprises a first semiconductor waveguide, a first SPP waveguide, and a second SPP waveguide; the second coupler comprises a second semiconductor waveguide, a third SPP waveguide, and a fourth SPP waveguide. The first semiconductor waveguide is located between the first and second SPP waveguides, and forms a V-shaped tip structure to achieve the conversion from optical wave mode to SPP mode. The second semiconductor waveguide is located between the third and fourth SPP waveguides, and has a V-shaped groove at its input end to achieve the conversion from SPP mode to optical wave mode. This invention can convert optical waves in a semiconductor to SPP mode in a metal waveguide, and can also transmit SPP mode from a metal waveguide to optical wave mode in a semiconductor waveguide.

Description

Technical Field

[0001] This invention relates to the field of integrated nanophotonic chip technology, specifically to a semiconductor waveguide and SPP waveguide coupler. Background Technology

[0002] In recent years, quantum information processing (QIP) has increasingly become a major research topic in the field of quantum optics. The realization of integrated nanophotonic chips is a key step in achieving on-chip integrated quantum technology platforms. In addition, nanophotonic integrated circuits have enormous application potential in data communication, signal processing, sensors, and quantum photonics. Integrated quantum chip technology requires coupling nanophotonic elements and photonic detection devices through low-loss waveguides to achieve on-chip processing systems. Currently, research on integrated micro / nanophotonic devices is mainly based on semiconductor materials and metal nanosurface plasmon (SPP) structures. Quantum light source research primarily utilizes semiconductor self-assembled quantum dots. From an application perspective, quantum dots can serve as single-photon sources and logic and storage elements, which are very useful for quantum information and computation. Furthermore, research on integrated nanophotonic devices based on photonic crystals also mainly utilizes semiconductor materials. SPPs, through strong field confinement, facilitate near-field coupling, and their ultra-small mode size facilitates device integration. Connecting semiconductor-based integrated nanophotonic devices with SPP-based integrated nanophotonic devices will undoubtedly lead to more powerful and comprehensive photonic chips. There is a significant difference between the k-wave vector in semiconductors and the k-wave vector in plasmas, which means that a large proportion of light waves cannot be directly coupled from semiconductors to plasma modes.

[0003] Therefore, how to provide a semiconductor waveguide and SPP waveguide coupler has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a semiconductor waveguide and SPP waveguide coupler that can convert light waves in the semiconductor into SPP mode of the metal waveguide, and can also convert the SPP mode of the metal waveguide into light wave mode in the semiconductor, thereby enabling the integration of semiconductor-based nanophotonic devices and SPP-based nanophotonic devices.

[0005] To achieve the above objectives, the present invention provides a semiconductor waveguide and SPP waveguide coupler, comprising: a first coupler and a second coupler, wherein the first coupler comprises a first semiconductor waveguide, a first SPP waveguide and a second SPP waveguide; and the second coupler comprises a second semiconductor waveguide, a third SPP waveguide and a fourth SPP waveguide.

[0006] The first SPP waveguide and the second SPP waveguide are arranged side by side at intervals. The first semiconductor waveguide is located between the first SPP waveguide and the second SPP waveguide. The first semiconductor waveguide forms a V-shaped tip structure along the optical wave propagation direction to realize the conversion from optical wave mode to SPP mode.

[0007] The third SPP waveguide and the fourth SPP waveguide are arranged side by side with intervals. The second semiconductor waveguide is located between the third SPP waveguide and the fourth SPP waveguide. The input end of the second semiconductor waveguide is provided with a V-groove, and the tip of the V-groove faces the output end of the second semiconductor waveguide, realizing the conversion from SPP mode to optical wave mode.

[0008] Furthermore, the first SPP waveguide of the first coupler is connected to the third SPP waveguide of the second coupler, and the second SPP waveguide of the first coupler is connected to the fourth SPP waveguide of the second coupler.

[0009] Furthermore, the first semiconductor waveguide is provided with a fixed width portion and a gradually decreasing width portion in sequence along the optical wave transmission direction. The width of the fixed width portion is a first fixed value, and the width of the gradually decreasing width portion gradually decreases from the first fixed value to zero along the optical wave transmission direction.

[0010] Furthermore, the gap size between the first SPP waveguide and the first semiconductor waveguide remains unchanged, and the gap size between the second SPP waveguide and the first semiconductor waveguide also remains unchanged.

[0011] Furthermore, the gap between the first SPP waveguide and the second SPP waveguide gradually decreases from a second fixed value to a third fixed value along the optical wave propagation direction, and the third fixed value is greater than zero; the second fixed value is greater than the first fixed value.

[0012] Furthermore, a quantum dot light source is integrated into the first semiconductor waveguide or connected to a semiconductor photonic circuit.

[0013] Furthermore, the width of the second semiconductor waveguide is constant along its length; the width of the V-groove opening is the same as the width of the second semiconductor waveguide; the gap between the third SPP waveguide and the fourth SPP waveguide is greater than the width of the second semiconductor waveguide; the gap size between the third SPP waveguide and the second semiconductor waveguide remains unchanged, and the gap size between the fourth SPP waveguide and the second semiconductor waveguide remains unchanged.

[0014] Furthermore, the first SPP waveguide of the first coupler is connected to the third SPP waveguide of the second coupler via a first SPP waveguide transition section, and the second SPP waveguide of the first coupler is connected to the fourth SPP waveguide of the second coupler via a second SPP waveguide transition section. The gap between the first SPP waveguide transition section and the second SPP waveguide transition section gradually increases from a third fixed value to a fourth fixed value along the optical wave propagation direction. The gap between the third SPP waveguide and the fourth SPP waveguide of the second coupler is equal to the fourth fixed value.

[0015] Furthermore, the second semiconductor waveguide is connected to the semiconductor photonic circuit.

[0016] Furthermore, the first SPP waveguide of the first coupler is connected to the third SPP waveguide of the second coupler via a first SPP waveguide transition section, and the second SPP waveguide of the first coupler is connected to the fourth SPP waveguide of the second coupler via a second SPP waveguide transition section, with SPP photonic devices connected in between, thereby realizing the integration of semiconductor-based integrated nanophotonic devices and SPP-based integrated nanophotonic devices.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention proposes a coupling device capable of converting energy between a semiconductor waveguide and an SPP waveguide, comprising a first coupler and a second coupler. The first coupler includes a first semiconductor waveguide, a first SPP waveguide, and a second SPP waveguide; the second coupler includes a second semiconductor waveguide, a third SPP waveguide, and a fourth SPP waveguide. The first semiconductor waveguide is located between the first and second SPP waveguides, and the second semiconductor waveguide is located between the third and fourth SPP waveguides. The width of the first semiconductor waveguide gradually decreases from a fixed value to zero along the optical wave propagation direction, forming a V-shaped tip structure. The input end of the second semiconductor waveguide has a V-shaped groove, with the tip of the V-shaped groove facing the output end of the semiconductor waveguide. This invention can convert light waves in a semiconductor into an SPP mode in a metal waveguide, and can also transmit the SPP mode of a metal waveguide to an optical wave mode in a semiconductor waveguide. This allows for the integration of semiconductor-based photonic devices and SPP-based photonic devices onto the same chip, achieving more comprehensive and powerful functionality. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the conversion of light waves in a semiconductor into SPP mode in a metal waveguide, according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram illustrating the conversion of the SPP mode of a metal waveguide into an optical wave mode in a semiconductor according to an embodiment of the present invention.

[0021] Figure 3This is a schematic diagram of a design model of a semiconductor waveguide and SPP waveguide coupler provided in one embodiment of the present invention;

[0022] Figure 4 A numerical simulation transmission diagram of light waves in a semiconductor being converted into SPP waves in a metal waveguide, according to an embodiment of the present invention;

[0023] Figure 5 Numerical simulation diagram of mode evolution from optical wave mode to SPP mode provided in one embodiment of the present invention;

[0024] Figure 6 A numerical simulation transmission diagram of the conversion of SPP waves in a metal waveguide into light waves in a semiconductor, provided in an embodiment of the present invention;

[0025] Figure 7 Numerical simulation diagram of the mode evolution from SPP mode to optical wave mode provided in one embodiment of the present invention.

[0026] In the figure:

[0027] 1-First semiconductor waveguide; 2-First SPP waveguide; 3-Second SPP waveguide; 4-Second semiconductor waveguide; 5-Third SPP waveguide; 6-Fourth SPP waveguide. Detailed Implementation

[0028] To achieve the above objectives and effects, the technical means and structure adopted by the present invention will be described in detail with reference to the accompanying drawings, focusing on the features and functions of the preferred embodiments of the present invention.

[0029] like Figure 1-3 As shown, the present invention provides a semiconductor waveguide and SPP waveguide coupler, comprising: a first coupler and a second coupler, wherein the first coupler comprises a first semiconductor waveguide 1, a first SPP waveguide 2 and a second SPP waveguide 3; and the second coupler comprises a second semiconductor waveguide 4, a third SPP waveguide 5 and a fourth SPP waveguide 6.

[0030] The first SPP waveguide 2 and the second SPP waveguide 3 are arranged side by side at intervals. The first semiconductor waveguide 1 is located between the first SPP waveguide 2 and the second SPP waveguide 3. The first semiconductor waveguide 1 forms a V-shaped tip structure along the optical wave propagation direction to realize the conversion from optical wave mode to SPP mode.

[0031] The third SPP waveguide 5 and the fourth SPP waveguide 6 are arranged side by side with intervals. The second semiconductor waveguide 4 is located between the third SPP waveguide 5 and the fourth SPP waveguide 6. The input end of the second semiconductor waveguide 4 is provided with a V-shaped groove, and the tip of the V-shaped groove faces the output end of the second semiconductor waveguide 4, realizing the conversion from SPP mode to optical wave mode.

[0032] In this embodiment, the first SPP waveguide 2 of the first coupler is connected to the third SPP waveguide 5 of the second coupler, and the second SPP waveguide 3 of the first coupler is connected to the fourth SPP waveguide 6 of the second coupler.

[0033] In this embodiment, the first semiconductor waveguide 1 is provided with a fixed width portion and a gradually decreasing width portion in sequence along the optical wave transmission direction. The width of the fixed width portion is a first fixed value, and the width of the gradually decreasing width portion gradually decreases from the first fixed value to zero along the optical wave transmission direction.

[0034] In this embodiment, the gap size between the first SPP waveguide 2 and the first semiconductor waveguide 1 remains unchanged, and the gap size between the second SPP waveguide 3 and the first semiconductor waveguide 1 also remains unchanged.

[0035] In this embodiment, the gap between the first SPP waveguide 2 and the second SPP waveguide 3 gradually decreases from a second fixed value to a third fixed value along the optical wave transmission direction, and the third fixed value is greater than zero; the second fixed value is greater than the first fixed value.

[0036] In this embodiment, a quantum dot light source is integrated into the first semiconductor waveguide 1 or connected to a semiconductor photonic circuit.

[0037] In this embodiment, the width of the second semiconductor waveguide 4 is constant along its length direction; the width of the V-groove opening is the same as the width of the second semiconductor waveguide 4; the gap between the third SPP waveguide 5 and the fourth SPP waveguide 6 is greater than the width of the second semiconductor waveguide 4; the gap size between the third SPP waveguide 5 and the second semiconductor waveguide 4 remains unchanged, and the gap size between the fourth SPP waveguide 6 and the second semiconductor waveguide 4 remains unchanged.

[0038] In this embodiment, the first SPP waveguide 2 of the first coupler is connected to the third SPP waveguide 5 of the second coupler via a transition section of the first SPP waveguide 2. The second SPP waveguide 3 of the first coupler is connected to the fourth SPP waveguide 6 of the second coupler via a transition section of the second SPP waveguide 3. The gap between the transition sections of the first SPP waveguide 2 and the second SPP waveguide 3 gradually increases from a third fixed value to a fourth fixed value along the optical wave propagation direction. The gap between the third SPP waveguide 5 and the fourth SPP waveguide 6 of the second coupler is equal to the fourth fixed value. The second SPP waveguide transition section can connect to SPP photonic devices, thereby realizing the integration of semiconductor-based integrated nanophotonic devices and SPP-based integrated nanophotonic devices.

[0039] In this embodiment, the second semiconductor waveguide 4 is connected to the semiconductor photonic circuit.

[0040] Furthermore, the first SPP waveguide 2, the second SPP waveguide 3, the third SPP waveguide 5, and the fourth SPP waveguide 6 are all metal SPP waveguides. In this embodiment, an aluminum gallium arsenide (AlGaAs) waveguide is selected as the transmission waveguide for optical waves, and a double-wire gold (Au) nanowaveguide is selected as the SPP transmission waveguide. The gap between the semiconductor material and the metal material is filled with air. The structure of this invention is not only applicable to semiconductor waveguides made of AlGaAs material and SPP waveguides made of gold material, but also applicable to waveguides made of various other semiconductor materials (such as gallium arsenide) and SPP waveguides made of other metals (such as silver).

[0041] like Figure 1 and Figure 2 As shown, this coupler can convert light waves in a semiconductor into SPP modes in a metal waveguide. The first semiconductor waveguide can either contain an integrated quantum dot light source or connect the coupler to a semiconductor photonic circuit. Light waves propagate from the left side of the first semiconductor waveguide to the coupler location. The width of the first semiconductor waveguide in this coupler gradually decreases to zero, while the air gap size between it and the metal SPP waveguide remains constant throughout this process. When the semiconductor width is large, the semiconductor mode is dominant; as the semiconductor width decreases, less energy remains in the semiconductor, and more and more energy concentrates in the gap, entering the plasma channel. For this tapered section, the semiconductor becomes smaller and smaller, thus the light wave mode gradually converts to more and more SPP modes. When the semiconductor disappears, the light wave mode is eventually completely converted to SPP mode.

[0042] Figure 4 This figure shows the optical field transmission diagram where light waves in a semiconductor are gradually converted into SPP waves in a metallic waveguide. This diagram was created using the numerical finite difference (FDTD) method. Figure 1 The numerical simulation results of the first coupler shown show that the light wave is incident from the left and propagates to the right. After passing through the first coupler, it is converted into an SPP wave and propagates at the interface between the gold double-wire waveguide and the air gap.

[0043] Figure 5 This figure shows the mode evolution numerical simulation of the V-shaped tip structure of the first semiconductor waveguide. The simulation was performed using the finite-difference numerical method (FDTD). Figure 1 The numerical simulation results of the coupler shown are as follows: Figure 5 (a)- Figure 5 (d) shows the cross-sectional optical field distribution at different locations of the coupler. For example... Figure 5 As shown in (a), when the semiconductor size is relatively large, the light wave energy is mainly concentrated in the first semiconductor waveguide; as Figure 5 (b) and Figure 5 (c) As the semiconductor size decreases, the energy within the semiconductor decreases, and more and more energy concentrates in the gaps, entering the plasma channels, and eventually, as... Figure 5As shown in (d), it has become a pure plasma mode in the air gap, that is, the conversion from light wave mode to SPP mode has been realized.

[0044] like Figure 1 and Figure 3 As shown, the coupler can convert the SPP mode of a metal waveguide into an optical mode in a semiconductor. The SPP wave is transmitted from the metal SPP double-wire waveguide on the left to the coupler position, gradually converting into an optical mode and connecting with the semiconductor photonic circuit. In this coupler, the air gap width between the metal double-wire waveguides gradually decreases to zero. As the air gap between the metals gradually decreases, the semiconductor mode gradually becomes dominant, and more and more energy enters the second semiconductor waveguide. The SPP mode optical mode is gradually converted into the optical mode in the semiconductor. When the air gap disappears, the SPP mode is finally completely converted into the optical mode.

[0045] Figure 6 This figure shows the optical field transmission diagram of the gradual conversion of SPP waves in a metallic waveguide into optical waves in a semiconductor. This diagram was created using the numerical finite difference (FDTD) method. Figure 2 The numerical simulation results of the coupler shown show that the SPP wave propagates from left to right, is converted into an optical wave by the coupler, and then propagates in the second semiconductor waveguide.

[0046] Figure 7 This figure shows the mode evolution simulation of the V-groove section of the second semiconductor waveguide. The simulation was performed using the Finite-Difference Numerical Method (FDTD). Figure 2 The numerical simulation results of the coupler shown are as follows: Figure 7 (a)- Figure 7 (d) shows the cross-sectional optical field distribution at different locations of the coupler. For example... Figure 7 As shown in (a), when there is no second semiconductor waveguide and the air gap size is relatively large, the energy is mainly distributed in the SPP mode on the metal surface; Figure 7 (b) and Figure 7 (c) As the air gap size decreases and the second semiconductor waveguide appears, energy gradually shifts from the SPP mode on the metal surface to the optical wave mode in the semiconductor. As the air gap becomes smaller and the second semiconductor waveguide size increases, more and more energy concentrates in the semiconductor, ultimately... Figure 7 As shown in (d), it has been transformed into the optical wave mode in the semiconductor, that is, the conversion from SPP mode to optical wave mode has been realized.

[0047] This invention proposes a coupling device capable of converting energy between a semiconductor waveguide and an SPP waveguide, comprising a first coupler and a second coupler. The first coupler includes a first semiconductor waveguide, a first SPP waveguide, and a second SPP waveguide; the second coupler includes a second semiconductor waveguide, a third SPP waveguide, and a fourth SPP waveguide. The first semiconductor waveguide is located between the first and second SPP waveguides, and the second semiconductor waveguide is located between the third and fourth SPP waveguides. The width of the first semiconductor waveguide gradually decreases from a fixed value to zero along the optical wave propagation direction, forming a V-shaped tip structure. The input end of the second semiconductor waveguide has a V-shaped groove, with the tip of the V-shaped groove facing the output end of the semiconductor waveguide. This invention can convert light waves in a semiconductor into an SPP mode in a metal waveguide, and can also transmit the SPP mode of a metal waveguide to an optical wave mode in a semiconductor waveguide. This allows for the integration of semiconductor-based photonic devices and SPP-based photonic devices onto the same chip, achieving more comprehensive and powerful functionality.

[0048] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A semiconductor waveguide and SPP waveguide coupler, characterized in that, include: A first coupler and a second coupler, wherein the first coupler includes a first semiconductor waveguide, a first SPP waveguide, and a second SPP waveguide; and the second coupler includes a second semiconductor waveguide, a third SPP waveguide, and a fourth SPP waveguide. The first SPP waveguide and the second SPP waveguide are arranged side by side at intervals. The first semiconductor waveguide is located between the first SPP waveguide and the second SPP waveguide. The first semiconductor waveguide forms a V-shaped tip structure along the optical wave propagation direction to realize the conversion from optical wave mode to SPP mode. The third SPP waveguide and the fourth SPP waveguide are arranged side by side with intervals. The second semiconductor waveguide is located between the third SPP waveguide and the fourth SPP waveguide. The input end of the second semiconductor waveguide is provided with a V-groove, and the tip of the V-groove faces the output end of the second semiconductor waveguide, so as to realize the conversion from SPP mode to optical wave mode. The width of the second semiconductor waveguide is constant along its length; the width of the V-groove opening is the same as the width of the second semiconductor waveguide; the gap between the third SPP waveguide and the fourth SPP waveguide is greater than the width of the second semiconductor waveguide; the gap size between the third SPP waveguide and the second semiconductor waveguide remains unchanged, and the gap size between the fourth SPP waveguide and the second semiconductor waveguide remains unchanged.

2. The semiconductor waveguide and SPP waveguide coupler as described in claim 1, characterized in that, The first SPP waveguide of the first coupler is connected to the third SPP waveguide of the second coupler, and the second SPP waveguide of the first coupler is connected to the fourth SPP waveguide of the second coupler.

3. The semiconductor waveguide and SPP waveguide coupler as described in claim 1, characterized in that, The first semiconductor waveguide has a fixed width section and a gradually decreasing width section in sequence along the optical wave propagation direction. The width of the fixed width section is a first fixed value, and the width of the gradually decreasing width section gradually decreases from the first fixed value to zero along the optical wave propagation direction.

4. A semiconductor waveguide and SPP waveguide coupler as described in claim 3, characterized in that, The gap size between the first SPP waveguide and the first semiconductor waveguide remains unchanged, and the gap size between the second SPP waveguide and the first semiconductor waveguide also remains unchanged.

5. A semiconductor waveguide and SPP waveguide coupler as described in claim 4, characterized in that, The gap between the first SPP waveguide and the second SPP waveguide gradually decreases from a second fixed value to a third fixed value along the optical wave propagation direction, and the third fixed value is greater than zero; the second fixed value is greater than the first fixed value.

6. A semiconductor waveguide and SPP waveguide coupler as described in claim 1 or 5, characterized in that, The first semiconductor waveguide integrates a quantum dot light source or connects it to a semiconductor photonic circuit.

7. A semiconductor waveguide and SPP waveguide coupler as described in claim 5, characterized in that, The first SPP waveguide of the first coupler is connected to the third SPP waveguide of the second coupler via a first SPP waveguide transition section. The second SPP waveguide of the first coupler is connected to the fourth SPP waveguide of the second coupler via a second SPP waveguide transition section. The gap between the first SPP waveguide transition section and the second SPP waveguide transition section gradually increases from a third fixed value to a fourth fixed value along the optical wave propagation direction. The gap between the third SPP waveguide and the fourth SPP waveguide of the second coupler is equal to the fourth fixed value.

8. A semiconductor waveguide and SPP waveguide coupler as described in claim 7, characterized in that, The second semiconductor waveguide is connected to the semiconductor photonic circuit.

9. A semiconductor waveguide and SPP waveguide coupler as described in claim 5, characterized in that, The first SPP waveguide of the first coupler is connected to the third SPP waveguide of the second coupler via a first SPP waveguide transition section, and the second SPP waveguide of the first coupler is connected to the fourth SPP waveguide of the second coupler via a second SPP waveguide transition section. SPP photonic devices are connected in between, thereby realizing the integration of semiconductor-based integrated nanophotonic devices and SPP-based integrated nanophotonic devices.

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