A nano-bridge filter based on a synthetic parameter space

Abstract

The application discloses a kind of nanobridge filter based on synthetic parameter space, including first grating coupler, first tapered waveguide, first straight waveguide, crystal nanobridge, second straight waveguide, second tapered waveguide and second grating coupler that are spliced in turn;Crystal nanobridge includes first photonic crystal nanobridge, second photonic crystal nanobridge formed by first cell periodic arrangement that are spliced in turn;First cell center in first cell is equipped with first air hole;Second air hole is equipped with at the distance cell center Δx in second cell;First cell is mediocre topological phase, and its Zak phase is zero;Second cell is non-mediocre topological phase, and its Zak phase is not zero;By introducing the displacement Δx of second air hole in second cell as a kind of synthetic dimension, when displacement Δx is uniformly changed within a cell length, its Zak phase is not zero, the filtering output of different wavelengths in large bandwidth is realized.The present application has the advantages of simple design structure, small floor area and wide adjustable filtering wavelength range.

Description

Technical Field

[0001] This invention relates to the field of micro-nano and integrated photonics technology, and more specifically, to a nanobridge filter based on a synthetic parameter space. Background Technology

[0002] Filters play a crucial role in integrated photonics applications, including wavelength division multiplexers and spectrometers. Filters selectively filter out specific wavelengths of light to achieve optical field manipulation. Photonic crystals have become an excellent platform for filter design. A photonic crystal is an artificial optical material with a periodic structure and exhibits a photonic bandgap, which is the frequency range in which light propagation is forbidden. The fabrication process of photonic crystals is compatible with integrated photonic chips, making it an effective solution for realizing on-chip micro / nano photonic devices with unique optical field manipulation capabilities.

[0003] Traditional photonic crystal filters introduce defects into the photonic crystal, specifically by disrupting its periodicity to create localized defects, thereby designing photonic crystal filters with defect modes and achieving selective transmission or blocking of specific wavelengths. Photonic crystal-based filters offer the advantage of miniaturization, and the transmission spectrum can be designed by adjusting the structural parameters of the introduced defects. This tunable transmission spectrum response enables customized filtering characteristics. However, it is worth noting that the tunable transmission spectrum response of photonic crystal-based filters is limited by the available parameters, which may restrict the achievable filtering wavelength range.

[0004] In recent years, topological photonic crystals have emerged as a rapidly developing research field, offering exciting prospects for novel optical field manipulation. In the field of photonic devices, high-performance waveguides and topological microcavities have been proposed and realized. However, realizing topological nanophotonic crystal devices remains challenging, primarily due to material limitations and design complexity. Summary of the Invention

[0005] To address the problems of complex design structure and narrow tunable filtering bandwidth in existing photonic crystal filters, this invention proposes a photonic crystal nanobridge filter based on the synthesis dimension, which has a series of outstanding advantages such as simple design structure, novel design principle, small footprint, and wide tunable filtering wavelength range.

[0006] To achieve the above-mentioned objectives of this invention, the technical solution adopted is as follows:

[0007] A nanobridge filter based on a synthetic parameter space includes a first grating coupler, a first tapered waveguide, a first straight waveguide, a crystal nanobridge, a second straight waveguide, a second tapered waveguide, and a second grating coupler.

[0008] The crystal nanobridges include a first photonic crystal nanobridge formed by the periodic arrangement of first unit cells and a second photonic crystal nanobridge formed by the periodic arrangement of second unit cells.

[0009] The first unit cell has a first air hole at the center of the unit cell; the second unit cell has a second air hole at a distance Δx from the center of the unit cell; the first unit cell is a trivial topological phase with zero Zach phase; the second unit cell is a non-trivial topological phase with non-zero Zach phase.

[0010] The first grating coupler is sequentially spliced ​​with the first tapered waveguide, the first straight waveguide, the crystal nanobridge, the second straight waveguide, the second tapered waveguide, and the second grating coupler to form a photonic crystal nanobridge filter.

[0011] By introducing the displacement Δx of the second air hole into the second unit cell as a synthesis dimension, when the displacement Δx changes uniformly within the length of a unit cell, its Zach phase is non-zero, and it can achieve filtered output of different wavelengths within a large bandwidth.

[0012] Preferably, the first grating coupler and the second grating coupler have the same structure, with a width of 11μm-13μm, a length of 49μm-51μm, an etching depth of 70nm-80nm, and an overall height of 210nm-230nm.

[0013] Preferably, the first tapered waveguide and the second tapered waveguide have the same structure, with the widest width being 11μm-13μm, the narrowest width being 490nm-510nm, the length being 99μm-101μm, and the height being 210nm-230nm.

[0014] Preferably, the first straight waveguide and the second straight waveguide have the same structure, with a width of 490nm-510nm, a length of 99μm-101μm, and a height of 210nm-230nm.

[0015] Preferably, the first unit cell and the second unit cell have the same lattice constant, with lattice constant a = 370nm-390nm.

[0016] Preferably, the range of Δx is [-190nm, 190nm].

[0017] Preferably, the first air hole in the first unit cell and the second air hole in the second unit cell are both set as square holes, with the air hole size d = 160nm-180nm.

[0018] Preferably, the overall width of the crystal nanobridge is 490nm-510nm, the length is 2.5μm-3.5μm, and the height is 210nm-230nm.

[0019] Preferably, the first grating coupler, the first tapered waveguide, the first straight waveguide, the crystal nanobridge, the second straight waveguide, the second tapered waveguide, and the second grating coupler are all made of silicon with a refractive index of 3.464.

[0020] Preferably, the background materials above and below the first grating coupler, the first tapered waveguide, the first straight waveguide, the crystal nanobridge, the second straight waveguide, the second tapered waveguide, and the second grating coupler are all air with a refractive index of 1.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention proposes a nanobridge filter based on a synthetic parameter space. It utilizes a design method based on synthetic dimensions to design photonic crystal nanobridge filters, allowing the exploration of topological physical phenomena in a higher-dimensional space beyond the geometric dimensions of traditional structures. Specifically, by introducing the displacement of air holes as a synthetic dimension, the relationship between the air hole displacement and the filter wavelength is established. Furthermore, by selecting appropriate parameters, a filter design with tunable wavelength over a large bandwidth can be achieved. This invention has significant advantages such as simple design structure, novel design principle, small footprint, and wide tunable filtering wavelength range, and is expected to open up new possibilities for realizing practical topological nanophotonic crystal devices. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the nanobridge filter based on the synthetic parameter space of the present invention.

[0024] Figure 2 This is a three-dimensional schematic diagram of the crystal nanobridge of the present invention.

[0025] Figure 3 This is a schematic diagram of the grating coupler of the present invention.

[0026] Figure 4 This is the transmission spectrum of the photonic crystal nanobridge filter with a displacement of Δx = 0.1a in this case.

[0027] Figure 5 This is the transmission spectrum of the photonic crystal nanobridge filter with a displacement of Δx = 0.2a in this case.

[0028] Figure 6 This is the transmission spectrum of the photonic crystal nanobridge filter with a displacement of Δx = 0.35a in this case.

[0029] Figure 7 This is the transmission spectrum of the photonic crystal nanobridge filter with a displacement of Δx = 0.5a in this case.

[0030] Figure 8This is the transmission spectrum of the photonic crystal nanobridge filter with a displacement of Δx = -0.3a in this case.

[0031] Figure 9 This is the transmission spectrum of the photonic crystal nanobridge filter with a displacement of Δx = -0.15a in this case.

[0032] Wherein: 1. First grating coupler; 2. First tapered waveguide; 3. First straight waveguide; 4. Crystal nanobridge; 5. Second straight waveguide; 6. Second tapered waveguide; 7. Second grating coupler; 8. First photonic crystal nanobridge; 9. Second photonic crystal nanobridge; 801. First unit cell; 901. Second unit cell; 802. First air hole; 902. Second air hole. Detailed Implementation

[0033] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0034] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0035] Example 1

[0036] like Figure 1 , Figure 2 The aforementioned nanobridge filter based on synthetic parameter space includes a first grating coupler 1, a first tapered waveguide 2, a first straight waveguide 3, a crystal nanobridge 4, a second straight waveguide 5, a second tapered waveguide 6, and a second grating coupler 7.

[0037] The crystal nanobridge 4 includes a first photonic crystal nanobridge 8 formed by the periodic arrangement of first unit cells 801 and a second photonic crystal nanobridge 9 formed by the periodic arrangement of second unit cells 901.

[0038] A first air hole 802 is provided at the center of the first unit cell 801; a second air hole 902 is provided at a distance Δx from the center of the second unit cell 901; the first unit cell 801 is a trivial topological phase with zero Zach phase; the second unit cell 901 is a non-trivial topological phase with non-zero Zach phase.

[0039] The first grating coupler 1 is sequentially spliced ​​with the first tapered waveguide 2, the first straight waveguide 3, the crystal nanobridge 4, the second straight waveguide 5, the second tapered waveguide 6, and the second grating coupler 7 to form a photonic crystal nanobridge filter.

[0040] By introducing the displacement Δx of the second air hole 902 into the second unit cell 901 as a synthesis dimension, when the displacement Δx changes uniformly within a unit cell length, its Zach phase is non-zero, and it can achieve filtered output of different wavelengths within a large bandwidth.

[0041] The working principle of this invention is as follows: Incident light is input from the first grating coupler 1, then sequentially passes through the first straight waveguide 3, the first photonic crystal nanobridge 8 formed by the periodic arrangement of the first unit cell 801, the second photonic crystal nanobridge 9 formed by the periodic arrangement of the second unit cell 901, the second straight waveguide 5, and the second tapered waveguide 6, and finally exits through the second grating coupler 7, where the test signal is received by the power meter. Furthermore, by introducing the displacement Δx of the air hole within the second unit cell 901 as a synthesis dimension, when Δx varies uniformly within a unit cell length, its Zach phase is non-zero, enabling filtered output of different wavelengths within a large bandwidth.

[0042] In one specific embodiment, the first grating coupler 1 and the second grating coupler 7 have the same structure, with a width of 11μm-13μm, a length of 49μm-51μm, a grating etching depth of 70nm-80nm, and an overall height of 210nm-230nm.

[0043] In one specific embodiment, the first tapered waveguide 2 and the second tapered waveguide 6 have the same structure, with the widest width being 11μm-13μm, the narrowest width being 490nm-510nm, the length being 99μm-101μm, and the height being 210nm-230nm.

[0044] In one specific embodiment, the first straight waveguide 3 and the second straight waveguide 5 have the same structure, with a width of 490nm-510nm, a length of 99μm-101μm, and a height of 210nm-230nm.

[0045] In one specific embodiment, the first unit cell 801 and the second unit cell 901 have the same lattice constant, lattice constant a = 370nm-390nm.

[0046] Preferably, the range of Δx is [-190nm, 190nm].

[0047] Preferably, the first air hole 802 in the first unit cell 801 and the second air hole 902 in the second unit cell 901 are both set as square holes, with the air hole size d = 160nm-180nm.

[0048] Preferably, the overall width of the crystal nanobridge 4 is 490nm-510nm, the length is 2.5μm-3.5μm, and the height is 210nm-230nm.

[0049] In one specific embodiment, the first grating coupler 1, the first tapered waveguide 2, the first straight waveguide 3, the crystal nanobridge 4, the second straight waveguide 5, the second tapered waveguide 6, and the second grating coupler 7 are all made of silicon with a refractive index of 3.464.

[0050] In one specific embodiment, the upper and lower background materials of the first grating coupler 1, the first tapered waveguide 2, the first straight waveguide 3, the crystal nanobridge 4, the second straight waveguide 5, the second tapered waveguide 6, and the second grating coupler 7 are all air with a refractive index of 1.

[0051] Example 2

[0052] Based on the nanobridge filter based on the synthetic parameter space described in the above embodiments, this embodiment sets the first grating coupler 1 and the second grating coupler 7 to have the same structure, with a width of 11μm, a length of 49μm, a grating etching depth of 70nm, and an overall height of 210nm.

[0053] The first tapered waveguide 2 and the second tapered waveguide 6 have the same structure, with the widest width being 11 μm, the narrowest width being 490 nm, the length being 99 μm, and the height being 210 nm.

[0054] The first straight waveguide 3 and the second straight waveguide 5 have the same structure, with a width of 490nm, a length of 99μm, and a height of 210nm.

[0055] The lattice constants a = 370 nm for the first unit cell 801 and the second unit cell 901.

[0056] The distance Δx from the center of the second unit cell 901 is -190nm.

[0057] The size of the first air hole 802 in the first unit cell 801 and the second air hole 902 in the second unit cell 901 is d = 160nm.

[0058] The crystal nanobridge 4 has an overall width of 490 nm, a length of 2.5 μm, and a height of 210 nm.

[0059] Example 3

[0060] Based on the nanobridge filter based on the synthetic parameter space described in the above embodiments, this embodiment sets the width of the first grating coupler 1 and the second grating coupler 7 to be 12μm, the length to be 50μm, the etching depth of the grating to be 75nm, and the overall height to be 220nm.

[0061] The first tapered waveguide 2 and the second tapered waveguide 6 both have a maximum width of 12 μm, a minimum width of 500 nm, a length of 100 μm, and a height of 220 nm.

[0062] The width of the first straight waveguide 3 and the second straight waveguide 5 are both 500nm, the length is 100μm, and the height is 220nm.

[0063] The lattice constants a = 380 nm for the first unit cell 801 and the second unit cell 901.

[0064] The distance Δx from the center of the second unit cell 901 is 0 nm, which is also the center of the second unit cell.

[0065] The air hole size d = 170 nm is the first air hole 802 in the first unit cell 801 and the second air hole 902 in the second unit cell 901.

[0066] The crystal nanobridge 4 has an overall width of 500 nm, a length of 3 μm, and a height of 220 nm.

[0067] Example 4

[0068] Based on the nanobridge filter based on the synthetic parameter space described in the above embodiments, this embodiment sets the width of the first grating coupler 1 and the second grating coupler 7 to be 13μm, the length to be 51μm, the etching depth of the grating to be 80nm, and the overall height to be 230nm.

[0069] The first tapered waveguide 2 and the second tapered waveguide 6 both have a maximum width of 13 μm, a minimum width of 510 nm, a length of 101 μm, and a height of 230 nm.

[0070] The width of the first straight waveguide 3 and the second straight waveguide 5 are both 510nm, the length is both 101μm, and the height is both 230nm.

[0071] The lattice constants a = 390 nm for the first unit cell 801 and the second unit cell 901.

[0072] The distance Δx from the center of the second unit cell 901 is 190 nm.

[0073] The air hole size d = 180nm for the first air hole 802 in the first unit cell 801 and the second air hole 902 in the second unit cell 901.

[0074] The crystal nanobridge 4 has an overall width of 510 nm, a length of 3.5 μm, and a height of 230 nm.

[0075] like Figure 3 The first grating coupler and the second grating coupler are formed by etching square air holes with a width of 60-80 nm and a thickness of 60-80 nm, with a length of 11-13 μm and a width of 400-500 nm, to form the first grating coupler and the second grating coupler.

[0076] To further verify the influence of displacement on the filtering wavelength of a nanobridge filter based on the synthetic parameter space, photonic crystal nanobridge filters with different displacements Δx were fabricated using a micro / nano fabrication platform. The transmission spectra of these filters with different displacements Δx were experimentally measured, and the results are shown below. Figures 4 to 9 As shown in the figure, the photonic crystal nanobridge filter with a displacement Δx = 0.1a has a transmission wavelength of 1300nm; the photonic crystal nanobridge filter with a displacement Δx = 0.2a has a transmission wavelength of 1333nm; the photonic crystal nanobridge filter with a displacement Δx = 0.35a has a transmission wavelength of 1399nm; the photonic crystal nanobridge filter with a displacement Δx = 0.5a has a transmission wavelength of 1467nm; the photonic crystal nanobridge filter with a displacement Δx = -0.3a has a transmission wavelength of 1520nm; and the photonic crystal nanobridge filter with a displacement Δx = 0.15a has a transmission wavelength of 1570nm. By changing the displacement, we can achieve filter outputs with different wavelengths and a bandwidth of 270nm.

[0077] This embodiment proposes a nanobridge filter based on a synthesis parameter space, employing a topology design method based on synthesis dimensions to create a photonic crystal nanobridge filter with topological protection. Specifically, by introducing the displacement of air holes as a synthesis dimension, the relationship between the air hole displacement and the filter wavelength is established. Through micro / nano fabrication and experimental testing, the design of the photonic crystal nanobridge filter is realized. This invention has significant advantages such as simple design structure, novel design principle, small footprint, and wide adjustable filter wavelength range, and is expected to open up new possibilities for realizing practical topological nanophotonic crystal devices.

[0078] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A nanobridge filter based on synthetic parameter space, characterized in that: It includes a first grating coupler (1), a first tapered waveguide (2), a first straight waveguide (3), a crystal nanobridge (4), a second straight waveguide (5), a second tapered waveguide (6), and a second grating coupler (7); The crystal nanobridge (4) includes a first photonic crystal nanobridge (8) formed by the periodic arrangement of first unit cells (801) and a second photonic crystal nanobridge (9) formed by the periodic arrangement of second unit cells (901); The first unit cell (801) has a first air hole (801) at the center of the unit cell; the second unit cell (901) has a second air hole (901) at a distance Δx from the center of the unit cell; the first unit cell (801) is a trivial topological phase with zero Zach phase; the second unit cell (901) is a non-trivial topological phase with non-zero Zach phase. The first grating coupler (1) is sequentially spliced ​​with the first tapered waveguide (2), the first straight waveguide (3), the crystal nanobridge (4), the second straight waveguide (5), the second tapered waveguide (6), and the second grating coupler (7) to form a photonic crystal nanobridge (4) filter; By introducing the displacement Δx of the second air hole (901) into the second unit cell (901) as a synthesis dimension, when the displacement Δx changes uniformly within the length of a unit cell, its Zach phase is non-zero, and it can achieve filtering output of different wavelengths within a large bandwidth.

2. The nanobridge filter based on the synthesis parameter space according to claim 1, characterized in that: The first grating coupler (1) and the second grating coupler (7) have the same structure, with a width of 11μm-13μm, a length of 49μm-51μm, a grating etching depth of 70nm-80nm, and an overall height of 210nm-230nm.

3. The nanobridge filter based on the synthetic parameter space according to claim 1, characterized in that: The first tapered waveguide (2) and the second tapered waveguide (6) have the same structure. The widest width is 11μm-13μm, the narrowest width is 490nm-510nm, the length is 99μm-101μm, and the height is 210nm-230nm.

4. The nanobridge filter based on the synthesis parameter space according to claim 1, characterized in that: The first straight waveguide (3) and the second straight waveguide (5) have the same structure, with a width of 490nm-510nm, a length of 99μm-101μm, and a height of 210nm-230nm.

5. The nanobridge filter based on the synthesis parameter space according to claim 1, characterized in that: The first unit cell (801) and the second unit cell (901) have the same lattice constant, a = 370nm - 390nm.

6. The nanobridge filter based on the synthetic parameter space according to claim 1, characterized in that: The range of Δx is [-190nm, 190nm].

7. The nanobridge filter based on the synthetic parameter space according to claim 1, characterized in that: The first air hole (801) in the first unit cell (801) and the second air hole (901) in the second unit cell (901) are both set as square holes with an air hole size d = 160nm-180nm.

8. The nanobridge filter based on the synthetic parameter space according to claim 1, characterized in that: The overall width of the crystal nanobridge (4) is 490nm-510nm, the length is 2.5μm-3.5μm, and the height is 210nm-230nm.

9. The nanobridge filter based on the synthesis parameter space according to claim 1, characterized in that: The first grating coupler (1), the first tapered waveguide (2), the first straight waveguide (3), the crystal nanobridge (4), the second straight waveguide (5), the second tapered waveguide (6) and the second grating coupler (7) are all made of silicon with a refractive index of 3.

464.

10. The nanobridge filter based on the synthetic parameter space according to claim 1, characterized in that: The background materials above and below the first grating coupler (1), the first tapered waveguide (2), the first straight waveguide (3), the crystal nanobridge (4), the second straight waveguide (5), the second tapered waveguide (6), and the second grating coupler (7) are all air with a refractive index of 1.

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