阅读说明：本技术 一种光通讯波段波分复用硅基能谷光子晶体结构 (Optical communication waveband wavelength division multiplexing silicon-based energy valley photonic crystal structure ) 是由 韩雨辉 费宏明 武敏 林瀚 张明达 刘欣 刘一超 陈智辉 陈靖 于 2021-06-11 设计创作，主要内容包括：本发明涉及拓扑光子晶体及集成光子芯片领域,公开了一种光通讯波段波分复用硅基能谷光子晶体结构,包括硅基底,所述硅基底通过三个分界线分割成四个区域,四个区域内第一圆形空气孔和第二圆形空气孔分别呈三角晶格交错设置并在分界线处形成四个拓扑波导结构,其中位于两侧的第二拓扑波导和第四拓扑波导分别采用半径不同的空气孔。两个波段的光波由第一拓扑波导进入,其中一个波段从第二拓扑波导出射,另一波段从第四拓扑波导出射,本发明可以用于实现微纳结构上的通讯光波段波分复用。(The invention relates to the field of topological photonic crystals and integrated photonic chips, and discloses a wavelength division multiplexing silicon-based energy valley photonic crystal structure of an optical communication waveband. The optical wave of two wave bands enters from the first topological waveguide, one wave band exits from the second topological waveguide, and the other wave band exits from the fourth topological waveguide.)

1. A wdm silicon-based energy valley photonic crystal structure for optical communications bands, comprising: the silicon substrate (1), a first dividing line (2), a second dividing line (3) and a third dividing line (4) are arranged on the silicon substrate (1), the first dividing line (2) is located on a straight line where a light incidence direction is located, the second dividing line (2) and the third dividing line (3) are symmetrically arranged on two sides of the silicon substrate, one end of the second dividing line is connected with the middle of the first dividing line (2), and the other end of the second dividing line extends to the edge of the photonic crystal structure in a direction parallel to the first dividing line (2) and far away from the light incidence side after inclining towards the light incidence side; the first dividing line (2), the second dividing line (3) and the third dividing line (4) divide the silicon substrate (1) into a first region (5), a second region (6), a third region (7) and a fourth region (8);

a plurality of circular air holes are distributed on the silicon substrate (1), and each air hole comprises a first circular air hole (9), a second circular air hole (10) and a third circular air hole (11); the radius of the first round air hole (9) is larger than that of the third round air hole (11), and the radius of the third round air hole (11) is larger than that of the second round air hole (10);

in the first area (5), the second area (6), the third area (7) and the fourth area (8), the first round air holes (9) and the second round air holes (10) are respectively arranged in a triangular lattice staggered manner, and a row of first round air holes (9) are respectively arranged in the first area (5) and the fourth area (8) close to the first boundary line (2) to form a first topological waveguide (12); a row of second circular air holes (10) are respectively arranged on the second area (6) and the third area (7) close to the first boundary line (2) to form a third topological waveguide (14); the first area (5) and the second area (6) are respectively provided with a row of first circular air holes (9) at a second boundary line (3) to form a second topological waveguide (13); and a row of third circular air holes (11) are respectively arranged on the two sides of the third demarcation line (4) of the third area (7) and the fourth area (8) to form a fourth topological waveguide (15).

2. A wavelength division multiplexed silicon based energy valley photonic crystal structure as claimed in claim 1, wherein said silicon substrate (1) has a refractive index of 3.48 and said air holes have a refractive index of 1.

3. A wdm silicon energy valley photonic crystal structure according to claim 1, wherein said triangular lattice has a lattice constant of a =450 nm and the radius of the first circular air hole (9) is r_a=120 nm, radius of the second circular air hole (10) being r_b=40 nm。

4. The WDM silicon-based energy valley photonic crystal structure of claim 1, wherein the radius of said third circular air hole (11) is r_c=100 nm。

5. A wavelength division multiplexing silicon-based energy valley photonic crystal structure of optical communication band as claimed in claim 1, wherein the air holes are uniformly distributed on the silicon substrate (1) in a hexagonal honeycomb dot shape.

6. A wavelength division multiplexed silicon based energy valley photonic crystal structure in optical communication band as claimed in claim 1 wherein the thickness of the silicon substrate (1) is 220 nm.

Technical Field

The invention relates to the field of topological photonics and integrated photonics, in particular to a wavelength division multiplexing silicon-based energy valley photonic crystal structure of an optical communication waveband based on topological edge state regulation.

Background

The energy valley photonic crystal wavelength division multiplexing device based on the micro-nano scale of the all-dielectric material is potentially applied to the fields of topological photonics and integrated photonics. At present, the wavelength division multiplexing device based on the topological photonic crystal still has the problems of complex structural design and incapability of realizing the wavelength division multiplexing device in a micro-nano structure, and cannot meet the practical application requirements of high integration level and the like in an integrated photonic chip.

In 2006, the Tapio Niemi group (wavelet-division multiplexing using photonic crystals waveguides, 2006,IEEE Photonics Technology Letters18,226-.

In 2020, the board creation group (Frequency range specific characters and sonic determining in spherical sonic crystals, 2020,Physical Review B102, 174202) designs a metal energy valley photonic crystal structure, which is composed of a triangular lattice of a metal rod array, and realizes the wavelength division multiplexing function of 12 GHz-22 GHz band by introducing edge state frequency freedom degree in the double band gap energy valley photonic crystal.

However, in the prior art, a wavelength division multiplexing device realized by a topological photonic crystal has the problem that the wavelength division multiplexing device cannot be realized in a micro-nano structure and is used for optical communication wave bands.

Disclosure of Invention

The invention overcomes the defects of the prior art, and solves the technical problems that: the utility model provides a light communication wave band wavelength division multiplexing silicon-based energy valley photonic crystal structure based on topological edge state regulation and control.

In order to solve the technical problems, the invention adopts the technical scheme that: a silicon-based energy valley photonic crystal structure for realizing wavelength division multiplexing function of communication optical bands comprises: the silicon substrate is provided with a first boundary line, a second boundary line and a third boundary line, the first boundary line is positioned on a straight line of a light incidence direction, the second boundary line and the third boundary line are symmetrically arranged on two sides of the silicon substrate, one end of the second boundary line is connected with the middle part of the first boundary line, and the other end of the second boundary line extends to the edge of the photonic crystal structure in a direction parallel to the first boundary line and far away from the light incidence side after inclining to the light incidence side; the first dividing line, the second dividing line and the third dividing line divide the silicon substrate into a first region, a second region, a third region and a fourth region;

a plurality of circular air holes are distributed on the silicon substrate, and the air holes comprise a first circular air hole, a second circular air hole and a third circular air hole; the radius of the first round air hole is larger than that of the third round air hole, and the radius of the third round air hole is larger than that of the second round air hole;

in the first area, the second area, the third area and the fourth area, the first round air holes and the second round air holes are respectively arranged in a triangular lattice staggered manner, and a row of first round air holes are respectively arranged in the first area and the fourth area close to a first boundary line to form a first topological waveguide; a row of second round air holes are respectively arranged at the second area and the third area close to the first boundary line to form a third topological waveguide; a row of first circular air holes are respectively arranged at the second dividing line of the first area and the second area to form a second topological waveguide; and the third area and the fourth area are respectively provided with a row of third circular air holes on two sides of the third boundary line to form a fourth topological waveguide.

The refractive index of the silicon substrate is 3.48, and the refractive index of the air hole is 1.

The triangular lattice has a lattice constant of a =450 nm and the radius of the first circular air hole is r_a=120 nm, radius of the second circular air hole r_b=40 nm。

The radius of the third round air hole is r_c=100 nm。

The air holes are uniformly distributed on the silicon substrate in a hexagonal honeycomb dot shape.

The thickness of the silicon substrate is 220 nm.

Compared with the prior art, the invention has the following beneficial effects: the invention provides a silicon-based energy valley photonic crystal structure for wavelength division multiplexing of optical communication wavebands, which can be manufactured by the aid of the existing CMOS technology and can realize the wavelength division multiplexing function of the communication optical wavebands on a micro-nano scale compared with the existing wavelength division multiplexing device realized on the basis of topological photonic crystals; compared with a wavelength division multiplexing device realized based on plain photonic crystals, the wavelength division multiplexing device has better anti-scattering light transmission performance, can realize light path regulation and control, and can be integrated in a photonic chip to meet the requirement of high integration level.

Drawings

Fig. 1 is a schematic structural diagram of a wdm-si based energy valley photonic crystal structure in an optical communication band according to an embodiment of the present invention.

FIG. 2 is a band diagram of the energy valley photonic crystal topology VPC1 in an embodiment of the present invention.

Fig. 3 is a diagram showing edge state energy band structures of waveguides 1 to 4 in the embodiment of the present invention.

FIG. 4 is a diagram showing the distribution of the electric field of TE mode optical wave transmission with wavelengths of 1478 nm and 1558 nm.

Fig. 5 is a graph of the transmittance at the exit of waveguide 2 to waveguide 4.

In the figure: 1 is a silicon substrate, and 2 is a first boundary line.

In the figure: 1 is, 2 is, 3 is the second boundary line, 4 is the third boundary line, 5 is the first region, 6 is the second region, 7 is the third region, 8 is the fourth region, 9 is the first circular air hole, 10 is the second circular air hole, 11 is the third circular air hole, 12 is the first topological waveguide, 13 is the second topological waveguide, 14 is the third topological waveguide, 15 is the fourth topological waveguide.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, an embodiment of the present invention provides a silicon-based energy valley photonic crystal structure for wavelength division multiplexing in optical communication bands, including: the silicon substrate 1 is provided with a first dividing line 2, a second dividing line 3 and a third dividing line 4, the first dividing line 2 is located on a straight line where the light incidence direction is located, the second dividing line 2 and the third dividing line 3 are symmetrically arranged on two sides of the silicon substrate 1, one end of the silicon substrate is connected with the middle of the first dividing line 2, and the other end of the silicon substrate extends to the edge of the photonic crystal structure in a direction parallel to the first dividing line 2 and far away from the light incidence side after inclining towards the light incidence side; the first, second and third dividing lines 2, 3, 4 divide the silicon substrate 1 into a first region 5, a second region 6, a third region 7 and a fourth region 8; a plurality of circular air holes are distributed on the silicon substrate 1, and the axial direction of each air hole is vertical to the plane of the silicon substrate 1 and penetrates through the silicon substrate 1. The air holes comprise a first round air hole 9, a second round air hole 10 and a third round air hole 11; the radius of the first circular air hole 9 is larger than that of the third circular air hole 11, and the radius of the third circular air hole 11 is larger than that of the second circular air hole 10.

As shown in fig. 1, in the first, second, third and fourth regions 5, 6, 7 and 8, the first circular air holes 9 and the second circular air holes 10 are respectively arranged in a triangular lattice staggered manner, and a row of first circular air holes 9 is respectively arranged in the first and fourth regions 5 and 8 near the first boundary line 2 to form a first topological waveguide 12; a row of second circular air holes 10 are respectively arranged on the second area 6 and the third area 7 close to the first dividing line 2 to form a third topological waveguide 14; the first area 5 and the second area 6 are respectively provided with a row of first circular air holes 9 at the second dividing line 3 to form a second topological waveguide 13; the third region 7 and the fourth region 8 are provided with a row of third circular air holes 11 on both sides of the third dividing line 4, respectively, to form a fourth topological waveguide 15.

Specifically, in this embodiment, the refractive index of the silicon substrate 1 is 3.48, and the refractive index of the air hole is 1. The triangular lattice has a lattice constant a =450 nm and the radius of the first circular air hole 9 is r_a=120 nm, radius of the second circular air hole 10 is r_b=40 nm, and the radius of the third circular air hole 11 is r_c=100 nm。

Specifically, in the present embodiment, the air holes are uniformly distributed on the silicon substrate 1 in a hexagonal honeycomb dot shape. That is, the centers of all the air holes are uniformly distributed in the form of hexagonal honeycomb dots on the entire silicon substrate 1.

Specifically, in this embodiment, the thickness of the silicon substrate 1 is 220 nm.

In this embodiment, light waves with two wavelength bands (1474 nm-1528 nm; 1558 nm-1620 nm) enter from one side of the first topological waveguide 12, light waves with 1474 nm-1528 nm wavelength bands exit from the second topological waveguide 13, light waves with 1558 nm-1620 nm wavelength bands exit from the fourth topological waveguide 15, and light waves with two wavelength bands cannot exit from the third topological waveguide 14.

The photonic crystal structure of the present embodiment is based on the CMOS process and includes the following steps. A standard SOI wafer with a top silicon layer of 220 nm thickness and a 3 μm thick silicon dioxide layer is first selected and first coated with a photoresist (ZEP 520A) on the silicon surface and then exposed using electron beam lithography followed by reactive ion etching using the photoresist as a mask layer, during which step it is important to obtain vertically etched sidewalls to maintain mirror symmetry of the photonic crystal structure with respect to the x-y plane located in the middle of the photonic crystal slab. And then on the basis, coating photoresist on the manufactured structure, simultaneously making a pattern to be etched on the photoresist, and then etching for 15 minutes by using diluted hydrofluoric acid by using the photoresist as a mask to remove the silicon dioxide substrate. This results in a suspended valley photonic crystal wavelength division multiplexing structure.

In this embodiment, the photonic crystal located on one side of the first waveguide and the third waveguide forms a first energy valley photonic crystal, and the photonic crystal located on the other side of the first waveguide and the third waveguide forms a second energy valley photonic crystal. As shown in fig. 2, which is an energy band diagram of a first energy valley photonic crystal in an embodiment of the present invention. In the figure, the shaded area of the bold line is the air light cone, and it can be seen that there is a TE mode band gap in the range of 1434 nm to 1687 nm, marked by the shaded area of the thin line. The second energy valley photonic crystal and the first energy valley photonic crystal have the same energy band structure.

FIG. 3 is a graph of the energy bands of the edge states of the first to fourth waveguides (WG 1-WG 4) according to the embodiment of the present invention, in which the hatched area of the thin line is the bulk state and the hatched area of the thick line is the cone of air. It can be seen from the figure that the second topological waveguide and the fourth topological waveguide are in two different wave bands, and the third topological waveguide is opposite to the first topological waveguide in the direction of the edge state group velocity vector.

As shown in fig. 4, for the distribution diagram of the transmission electric field of the TE mode light waves with wavelengths of 1478 nm and 1558 nm, respectively, since 1478 nm and 1558 nm are respectively located in the operating bands of the second topology waveguide and the fourth topology waveguide, the 1478 nm light wave is transmitted and output by the second topology waveguide, and the 1558 nm light wave is transmitted and output by the fourth topology waveguide.

As shown in fig. 5, which is a graph of the transmittance at the exit of the waveguides 2 to 4, it can be seen that the second topology waveguide dominates at the output end in the 1474 nm-1528 nm operating band of the second topology waveguide, and the fourth topology waveguide dominates at the output end in the 1558 nm-1620 nm operating band of the fourth topology waveguide. The third topology waveguide output continuously maintains low transmissivity. Therefore, the structure can be shown to realize the function of wavelength division multiplexing.

The heterostructure designed by the invention realizes different path selective transmission of different wave bands in the wave band near 1550 nm, and can be used for realizing the wavelength division multiplexing function in a micro-nano structure.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.