Topological photonic crystal nano-beam cavity electrically-driven laser and manufacturing method thereof

Abstract

The invention belongs to the technical field of photoelectronics, and particularly relates to a topological photonic crystal nano-beam cavity electrically-driven laser and a manufacturing method thereof.The topological photonic crystal nano-beam cavity electrically-driven laser comprises an SOI waveguide structure, an InP heterostructure is arranged above the SOI waveguide structure, a nano-beam cavity is formed in the InP heterostructure, the InP heterostructure is electrically connected with a power-on structure, and the power-on structure is electrically connected with the power-on structure. The outer sides of the InP heterostructure and the SOI waveguide structure are coated with a SiO2 passivation layer, and the electrifying structure penetrates out of the SiO2 passivation layer; the nano-beam cavity at least comprises PC1 of a plurality of periods and PC2 of a plurality of periods, the PC1 and the PC2 are arranged on the InP heterostructure, the PC1 and the PC2 are arranged in sequence, and the Zak phases of the PC1 and the PC2 are different. The laser is insensitive to defects, has a larger quality factor Q and a smaller mode volume V, and can realize a lower threshold and a higher modulation rate.

Description

Technical Field

[0001] The invention belongs to the field of optoelectronic technology, and in particular relates to a topological photonic crystal nanobeam cavity electrically driven laser and a manufacturing method thereof. Background Art

[0002] Optical cavities with high quality factor (Q factor) have important applications in narrowband filtering, ultra-low energy switching and modulation, sensing, etc. Among them, nanobeam cavities (one-dimensional photonic crystal cavities) have attracted widespread attention because they can achieve high Q factors in addition to providing design flexibility and relatively simple fabrication.

[0003] One-dimensional nanobeam cavities can provide Q / V comparable to two-dimensional photonic crystal cavities, but with much smaller bottom area and mass, relatively easy to design and manufacture, and a tendency to couple with line waveguides. Due to the above unique properties, one-dimensional PC nanobeam cavities have become a powerful alternative to two-dimensional PC cavities in recent years. Structures based on one-dimensional PC nanobeam cavities have achieved great research significance and have been implemented in many research applications, such as ultra-small nanolasers, optical sensors, optical switches, nano-tweezers, etc.

[0004] However, ordinary nanobeam lasers are very sensitive to manufacturing defects, material defects, and fluctuations in the operating environment. These defects can cause scattering losses and reduce the performance of the laser, such as increasing the threshold current, reducing the output power, and shortening the service life. And they usually support multiple optical modes, and to achieve efficient and stable single-mode laser output, the size and shape of the nanobeams must be precisely controlled. This is very difficult in actual manufacturing and has a low tolerance for processing errors. Summary of the invention

[0005] The purpose of the present invention is to provide a topological photonic crystal nanobeam cavity electrically driven laser and a manufacturing method thereof to solve the above problems.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A topological photonic crystal nanobeam cavity electrically driven laser comprises a SOI waveguide structure, an InP heterostructure is arranged above the SOI waveguide structure, a nanobeam cavity is arranged on the InP heterostructure, the InP heterostructure is electrically connected to a power-on structure, and the outer sides of the InP heterostructure and the SOI waveguide structure are coated with SiO 2 Passivation layer, the power-on structure penetrates the SiO 2 Passivation layer;

[0008] The nanobeam cavity at least includes multiple periods of PC1 and multiple periods of PC2 opened on the InP heterostructure, the multiple PC1 and the multiple PC2 are arranged in sequence, and the Zak phases of the PC1 and the PC2 are different.

[0009] Preferably, the PC1 includes an air hole on the left side of PC1 and an air hole on the right side of PC1 opened on the InP heterostructure, the PC1 occupies a lattice constant a, the center of the air hole on the left side of PC1 is located at 0.25a, ​​the center of the air hole on the right side of PC1 is located at 0.75a, and the diameters of the air hole on the left side of PC1 are not equal to those of the air hole on the right side of PC1.

[0010] Preferably, the PC2 includes an air hole on the left side of PC2 and an air hole on the right side of PC2 opened on the InP heterostructure, the PC2 occupies a lattice constant a, the center of the air hole on the left side of PC2 is located at 0.25a, ​​the center of the air hole on the right side of PC2 is located at 0.75a, the diameter of the air hole on the left side of PC2 is equal to that of the air hole on the right side of PC1, and the diameter of the air hole on the right side of PC2 is equal to that of the air hole on the left side of PC1.

[0011] Preferably, the SOI waveguide structure comprises a Si-based substrate layer, a thermally oxidized SiO 2 layer, the thermally oxidized SiO 2 A Si waveguide is arranged above the layer, and the thermally oxidized SiO 2 A BCB layer is disposed above the Si layer, and the BCB layer is coated on the outside of the Si waveguide.

[0012] Preferably, the InP heterostructure comprises a P-doped layer, an active region, and an N-doped layer arranged in sequence from bottom to top, and the outer sides of the P-doped layer, the active region, and the N-doped layer are coated with SiO 2 layer, the PC1 left air hole, the PC1 right air hole, the PC2 left air hole and the PC2 right air hole penetrate the P-doped layer, the active area and the N-doped layer.

[0013] Preferably, the power-on structure includes a P electrode electrically connected to the P-doped layer and an N electrode electrically connected to the N-doped layer, and both the P electrode and the N electrode pass through the SiO 2 Passivation layer.

[0014] A method for manufacturing the topological photonic crystal nanobeam cavity electrically driven laser comprises:

[0015] Fabricating an InP heterostructure on an InP substrate, fabricating an SOI wafer into an SOI waveguide structure, bonding the InP heterostructure to the SOI waveguide structure, and removing the InP substrate and the etch stop layer;

[0016] Multiple periods of PC1 and multiple periods of PC2 are fabricated on the InP heterostructure. The Zak phases of PC1 and PC2 are different, and a topologically protected interface state is formed at the junction of PC1 and PC2.

[0017] The power-on structure is prepared on the InP heterostructure, and SiO is deposited on the surface of the InP heterostructure and the SOI waveguide structure. 2 The passivation layer is used for surface passivation and encapsulation. 2 Through holes are etched in the passivation layer to lead the power-on structure to the surface of the laser.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] The present invention utilizes the splicing of PC1 and PC2 of different Zak phases to form a topologically protected interface state at the interface, thereby obtaining a large photon bandgap, obtaining efficient and stable single-mode lasing, and confining the light field at the splicing interface, which can effectively increase the quality factor and reduce the mode volume, obtain a higher modulation bandwidth, reduce the threshold current, and reduce the impact of errors caused by the process, thereby improving the reliability and repeatability of the laser and enhancing the performance of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0021] Figure 1 is a cross-sectional view of the laser in the present invention;

[0022] Figure 2 A top view of the laser in the present invention;

[0023] Figure 3 is the energy band distribution diagram of different photonic crystals in the present invention;

[0024] Figure 4 is the transmission spectrum;

[0025] Figure 5 This is the light field distribution diagram of light with a wavelength of 1550nm in the nanobeam cavity;

[0026] Wherein, 101, Si-based substrate layer; 102, thermally oxidized SiO 2 layer; 103, Si waveguide; 200, BCB layer; 300, SiO 2 layer; 401, P-doped layer; 402, active region; 403, N-doped layer; 500, SiO 2 Passivation layer; 600, P electrode; 700, N electrode; 801, air hole on the left side of PC1; 802, air hole on the right side of PC1; 901, air hole on the left side of PC2; 902, air hole on the right side of PC2. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Reference Figure 1 to Figure 2 The present invention discloses a topological photonic crystal nanobeam cavity electrically driven laser, comprising a SOI waveguide structure, an InP heterostructure disposed above the SOI waveguide structure, a nanobeam cavity disposed on the InP heterostructure, the InP heterostructure electrically connected to a power-on structure, and the outer sides of the InP heterostructure and the SOI waveguide structure coated with SiO 2 Passivation layer 500, the power-on structure penetrates SiO 2 Passivation layer 500;

[0030] The nanobeam cavity at least includes multiple periods of PC1 and multiple periods of PC2 opened on the InP heterostructure, the multiple PC1 and the multiple PC2 are arranged in sequence, and the Zak phases of PC1 and PC2 are different.

[0031] In a specific example of the present invention, the topological photonic crystal nanobeam cavity electrically driven laser includes multiple periods of PC1, multiple periods of PC2;

[0032] A further optimization scheme is adopted, in which PC1 includes an air hole 801 on the left side of PC1 and an air hole 802 on the right side of PC1 which are opened on the InP heterostructure. PC1 occupies a lattice constant a. The center of the air hole 801 on the left side of PC1 is located at 0.25a, ​​and the center of the air hole 802 on the right side of PC1 is located at 0.75a. The diameters of the air hole 801 on the left side of PC1 and the air hole 802 on the right side of PC1 are not equal.

[0033] Further optimization scheme, PC2 includes air hole 901 on the left side of PC2 and air hole 902 on the right side of PC2 opened on the InP heterostructure, PC2 occupies a lattice constant a, the center of air hole 901 on the left side of PC2 is located at 0.25a, ​​the center of air hole 902 on the right side of PC2 is located at 0.75a, the diameter of air hole 901 on the left side of PC2 is equal to the diameter of air hole 802 on the right side of PC1, and the diameter of air hole 902 on the right side of PC2 is equal to the diameter of air hole 801 on the left side of PC1.

[0034] Assume that the right air hole 802 of PC1 and the left air hole 901 of PC2 where PC2 and PC1 are close to each other form PC3. PC3 has the same structure as PC1 and PC2, but the diameters of its left and right air holes are equal, and its lattice constant is also a.

[0035] The nanobeam cavity of the present invention has topologically protected edge states that are highly robust to defects and disturbances. Even in the presence of manufacturing defects or environmental fluctuations, the laser using the nanobeam cavity of the present invention can maintain stable laser output. The topological structure can effectively suppress unnecessary optical modes, thereby making it easier to achieve single-mode laser output and improve the efficiency and stability of the laser.

[0036] The nanobeam cavity is formed by splicing two different one-dimensional photonic crystals PC1 and PC2, and the different Zak phases of the two different photonic crystals are used to generate a topological interface state at the splicing interface. Since PC1 and PC2 have the same bandgap structure, the two photonic crystals will produce the same forbidden band, and in the spliced ​​photonic crystals, a transmission peak formed by a topological interface state will be generated in the forbidden band, which can effectively suppress the unwanted longitudinal mode, making it easier to achieve single-mode laser output and improve the efficiency and stability of the laser. In addition, the nanobeam cavity has a higher quality factor and a smaller mode volume. The nanobeam cavity suitable for high-speed and low-energy photonic crystal nanobeam lasers is designed by combining the rate equation and the high-speed modulation theory to optimize the parameters. Using a topological nanobeam structure as a nanobeam cavity, compared with the existing laser resonant cavity, the laser of the present invention has a larger quality factor Q and a smaller mode volume V, which can achieve a lower threshold and a higher modulation rate.

[0037] Further optimizing the scheme, the SOI waveguide structure includes a Si-based substrate layer 101, a thermally oxidized SiO 2 Layer 102, thermally oxidized SiO 2 A Si waveguide 103 is provided above the layer 102, and the SiO 2 A BCB layer 200 is disposed above the layer 102 , and the BCB layer 200 covers the outside of the Si waveguide 103 .

[0038] Further optimized solution, the InP heterostructure includes a P-doped layer 401, an active area 402, and an N-doped layer 403 arranged in sequence from bottom to top, and the outer sides of the P-doped layer 401, the active area 402, and the N-doped layer 403 are coated with SiO 2 Layer 300 , the air hole 801 on the left side of PC1 , the air hole 802 on the right side of PC1 , the air hole 901 on the left side of PC2 , and the air hole 902 on the right side of PC2 penetrate the P-doped layer 401 , the active area 402 , and the N-doped layer 403 .

[0039] Further optimized solution, the power-on structure includes a P electrode 600 electrically connected to the P doped layer 401 and an N electrode 700 electrically connected to the N doped layer 403, and the P electrode 600 and the N electrode 700 both penetrate the SiO 2 Passivation layer 500 .

[0040] A method for manufacturing a topological photonic crystal nanobeam cavity electrically driven laser, comprising:

[0041] Fabricating an InP heterostructure on an InP substrate, fabricating an SOI wafer into an SOI waveguide structure, bonding the InP heterostructure to the SOI waveguide structure, and removing the InP substrate and the etch stop layer;

[0042] Multiple periods of PC1 and multiple periods of PC2 are fabricated on the InP heterostructure. The Zak phases of PC1 and PC2 are different, and a topologically protected interface state is formed at the junction of PC1 and PC2.

[0043] The power-on structure is prepared on the InP heterostructure, and SiO is deposited on the surface of the InP heterostructure and the SOI waveguide structure. 2 The passivation layer 500 performs surface passivation and encapsulation. 2 A through hole is etched on the passivation layer 500 to lead the power-on structure to the surface of the laser.

[0044] Specific production method:

[0045] An N-doped layer 403, an active region 402, and a P-doped layer 401 are sequentially grown on an InP substrate by using an organic metal chemical vapor deposition (MOCVD) technique, and a SiO layer 300 is covered on the outer sides of the N-doped layer 403, the active region 402, and the P-doped layer 401;

[0046] A waveguide structure is formed on an SOI wafer by dry etching, and a BCB layer 200 is coated on the surface of the waveguide structure by a spin coating process to form an SOI waveguide structure. The InP heterostructure and the SOI waveguide structure are bonded in a vacuum by a thermal pressing process, and the P-doped layer 401 is close to the SOI waveguide structure. After bonding, the InP substrate and the etching stop layer are removed, and only the required InP heterostructure is retained;

[0047] Using electron beam exposure (EBL) and inductively coupled plasma etching (ICP) processes, multiple periods of PC1 and PC2 of the same period are etched on the InP heterostructure to form a nanobeam cavity. The nanobeam cavity uses PC1 and PC2 with different Zak phases to splice together, forming a topologically protected interface state at the splicing point. This interface state enables the nanobeam resonant cavity to have a higher quality factor Q and a smaller mode volume V, achieving the effect of limiting the light field. At the same time, the robustness of the topological interface state can also reduce defects caused by the process, etc., and improve the reliability and repeatability of the device;

[0048] The ohmic contact electrodes P electrode 600 and N electrode 700 are prepared on the P-doped layer 401 and N-doped layer 403 of the InP heterostructure by electron beam evaporation technology for current injection and device testing, and SiO 2 The passivation layer 500 is surface passivated and packaged, and then dry etching is used to implement through-hole etching to lead the P electrode 600 and N electrode 700 buried deep below to the surface of the laser.

[0049] The present invention provides a topological photonic crystal nanobeam cavity electrically driven laser and a manufacturing method thereof, using a topological photonic crystal nanobeam cavity, an active region 402, an InP heterostructure, and a SiO 2 A topological photonic crystal nanobeam cavity electrically driven laser composed of layer 300, SOI waveguide structure, etc.; the nanobeam cavity of the present invention is not limited to having only one topological interface state, but can also be a photonic crystal nanobeam cavity with two, three, or more than one interface state and multiple Zak phases.

[0050] Reference Figure 3 , the band diagram of PC1 is as follows Figure 3 (a) shows the energy band diagram of PC3. Figure 3 (b) shows the energy band diagram of PC2. Figure 3 As shown in (c), PC3 is essentially to set the radius of the two air holes of PC1 or PC2 to be the same, and the diameter of the air hole 802 on the right side of PC1 is the same as the diameter of the air hole 901 on the left side of PC2.

[0051] The radii of the air holes etched at 0.25a and 0.75a in PC1 and PC2 are different (i.e., the radii of air hole 801 on the left side of PC1 and air hole 901 on the left side of PC2 are not equal, and the radii of air hole 802 on the right side of PC1 and air hole 902 on the right side of PC2 are not equal), so PC1 and PC2 will have different Zak phases. One-dimensional systems with different Zak phases are topologically unequal, and the mutual transformation between topologically unequal systems is called a topological phase transition. Topological phase transitions are usually manifested in energy bands as a process of crossing and then opening the energy bands. In order to demonstrate this topological phase transition, the adiabatic evolution process can be simulated by gradually changing the radii at 0.25a and 0.75a in the primitive cell. By reducing the radius at 0.25a in PC1 and increasing the radius at 0.75a, we obtain Figure 3 (a)-(c) energy band dispersion relation. Comparing the energy band diagram, we can see that the band gap closes when PC1 changes to PC3, which is the topological phase transition point. The band gap opens when PC3 changes to PC2, completing the topological phase transition from PC1 to PC2. Therefore, PC1 and PC2 are topologically inequivalent. When two topologically inequivalent photonic crystals are spliced, a topological interface state will be formed at the splicing position. The transmission spectrum finally obtained by the finite element method is shown in Figure 4 As shown, the light field distribution of light with a wavelength of 1550nm in the nanobeam cavity is as follows Figure 5 shown.

[0052] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0053] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A topological photonic crystal nanobeam cavity electrically driven laser, characterized in that: It comprises a SOI waveguide structure, an InP heterostructure is arranged above the SOI waveguide structure, a nanobeam cavity is arranged on the InP heterostructure, the InP heterostructure is electrically connected to a power-on structure, the outer sides of the InP heterostructure and the SOI waveguide structure are coated with a SiO2 passivation layer (500), and the power-on structure passes through the SiO2 passivation layer (500); The nanobeam cavity at least includes multiple periods of PC1 and multiple periods of PC2 opened on the InP heterostructure, the multiple PC1 and the multiple PC2 are arranged in sequence, and the Zak phases of the PC1 and the PC2 are different.

2. A topological photonic crystal nanobeam cavity electrically driven laser according to claim 1, characterized in that: The PC1 includes an air hole (801) on the left side of the PC1 and an air hole (802) on the right side of the PC1 opened on the InP heterostructure. The PC1 occupies a lattice constant a. The center of the air hole (801) on the left side of the PC1 is located at 0.25a, ​​and the center of the air hole (802) on the right side of the PC1 is located at 0.75a. The diameters of the air hole (801) on the left side of the PC1 are not equal to those of the air hole (802) on the right side of the PC1.

3. A topological photonic crystal nanobeam cavity electrically driven laser according to claim 2, characterized in that: The PC2 includes an air hole (901) on the left side of the PC2 and an air hole (902) on the right side of the PC2 opened on the InP heterostructure. The PC2 occupies a lattice constant a. The center of the air hole (901) on the left side of the PC2 is located at 0.25a, ​​and the center of the air hole (902) on the right side of the PC2 is located at 0.75a. The diameters of the air hole (901) on the left side of the PC2 and the air hole (802) on the right side of the PC1 are equal, and the diameters of the air hole (902) on the right side of the PC2 and the air hole (801) on the left side of the PC1 are equal.

4. A topological photonic crystal nanobeam cavity electrically driven laser according to claim 3, characterized in that: The SOI waveguide structure comprises a Si-based substrate layer (101) and a thermally oxidized SiO2 layer (102) which are sequentially arranged from bottom to top; a Si waveguide (103) is arranged above the thermally oxidized SiO2 layer (102); a BCB layer (200) is arranged above the thermally oxidized SiO2 layer (102); and the BCB layer (200) is coated on the outside of the Si waveguide (103).

5. A topological photonic crystal nanobeam cavity electrically driven laser according to claim 4, characterized in that: The InP heterostructure comprises a P-doped layer (401), an active area (402), and an N-doped layer (403) arranged in sequence from bottom to top, wherein the outer sides of the P-doped layer (401), the active area (402), and the N-doped layer (403) are coated with a SiO2 layer (300), and the air hole on the left side of PC1 (801), the air hole on the right side of PC1 (802), the air hole on the left side of PC2 (901), and the air hole on the right side of PC2 (902) penetrate the P-doped layer (401), the active area (402), and the N-doped layer (403).

6. A topological photonic crystal nanobeam cavity electrically driven laser according to claim 5, characterized in that: The power-on structure comprises a P electrode (600) electrically connected to the P-doped layer (401) and an N electrode (700) electrically connected to the N-doped layer (403), and both the P electrode (600) and the N electrode (700) penetrate through the SiO2 passivation layer (500).

7. A method for manufacturing a topological photonic crystal nanobeam cavity electrically driven laser according to any one of claims 1 to 6, comprising: Fabricating an InP heterostructure on an InP substrate, fabricating an SOI wafer into an SOI waveguide structure, bonding the InP heterostructure to the SOI waveguide structure, and removing the InP substrate and the etch stop layer; Multiple periods of PC1 and multiple periods of PC2 are fabricated on the InP heterostructure. The Zak phases of PC1 and PC2 are different, and a topologically protected interface state is formed at the junction of PC1 and PC2. A power-on structure is prepared on the InP heterostructure, a SiO2 passivation layer (500) is deposited on the surface of the InP heterostructure and the SOI waveguide structure for surface passivation and packaging, and a through hole is etched on the SiO2 passivation layer (500) to lead the power-on structure to the surface of the laser.

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