Optical waveguide amplifier and method for manufacturing an optical waveguide amplifier

Abstract

This invention provides an optical waveguide amplifier and a method for fabricating it. The optical waveguide amplifier includes a substrate layer, an insulating layer, a passive waveguide layer, and multiple doped layers. The insulating layers are stacked on the substrate layer. The passive waveguide layer and the multiple doped layers are stacked on the insulating layer. An m-layer doped layer is disposed above the passive waveguide layer, and an n-layer doped layer is disposed below it, where m and n are integers, m+n≥2, and m≥0, n≥0. The multiple doped layers are doped with various rare-earth ions. Compared to fiber amplifiers doped with rare-earth elements, the optical waveguide amplifier in this embodiment is smaller, which simplifies the device structure, reduces device size, and lowers costs. Compared to existing on-chip optical waveguide amplifiers, the optical waveguide amplifier in this embodiment can be doped with various rare-earth ions, enabling the amplification of broadband signals and broadening its applicability.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to an optical waveguide amplifier and a method for fabricating the optical waveguide amplifier. Background Technology

[0002] Amplifiers play a crucial role in optical communication networks. During long-distance transmission, optical signals experience transmission loss within the optical fiber. To ensure the receiver receives a sufficiently strong optical signal and guarantees signal quality, amplifiers are used to amplify the optical signal and compensate for this transmission loss.

[0003] The main principle of existing amplifiers is to dope optical fibers with rare earth elements, for example, by placing a section of rare earth-doped optical fiber amplifier near the receiving end. However, in order to meet the signal quality requirements of the receiving end, the length of the rare earth-doped optical fiber amplifier is relatively large, which is not conducive to the miniaturization of the equipment.

[0004] With the development of on-chip integration technology, there is now an optical waveguide amplifier doped with rare earth elements. Compared with fiber amplifiers doped with rare earth elements, it is smaller in size, which can simplify the equipment and reduce costs. Existing optical waveguide amplifiers are mainly designed according to the specific emission bands of different rare earth elements. For example, erbium-doped optical waveguide amplifiers have excellent amplification effects in the communication band (C-band, 1532nm-1565nm), praseodymium ions correspond to the O-band, thulium ions correspond to the S+U-band, and so on.

[0005] However, existing optical waveguide amplifiers have bandwidth limitations, making it difficult to achieve wide-spectrum signal amplification on a single device. Furthermore, high signal gain and low transmission loss have always been sought-after performance indicators for optical waveguide amplifiers, but existing rare-earth-doped optical waveguide amplifiers still suffer from significant losses, severely hindering their widespread application.

[0006] The content of the background section is merely the technology known to the inventor and does not necessarily represent the prior art in this field. Summary of the Invention

[0007] To address one or more of the problems existing in the prior art, the present invention provides an optical waveguide amplifier, comprising:

[0008] Substrate layer;

[0009] An insulating layer is stacked on the substrate layer;

[0010] A passive waveguide layer and multiple doped layers are stacked on the insulating layer;

[0011] The passive waveguide layer is provided with m doped layers above it and n doped layers are provided below it, where m and n are integers, m+n≥2, and m≥0, n≥0;

[0012] The multilayer doped layer is doped with a variety of rare earth ions.

[0013] According to one aspect of the invention, the optical waveguide amplifier further includes a capping layer, wherein m = 0 and n ≥ 2, the capping layer is disposed on the passive waveguide layer; or m ≥ 1 and n ≥ 1, the capping layer is disposed on the uppermost doped layer; or m ≥ 2 and n = 0, the capping layer is disposed on the uppermost doped layer, the passive waveguide layer being adjacent to the insulating layer.

[0014] According to one aspect of the invention, the optical waveguide amplifier further includes buffer layers disposed between adjacent doped layers.

[0015] According to one aspect of the present invention, the substrate layer is made of any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, and silicon carbide; the insulating layer is made of any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, silicon carbide, and silicon oxide; the doped layer is made of one or more of aluminum oxide, tantalum oxide, silicon nitride, lithium niobate, or titanium oxide; and the rare earth ions include any one or more of erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

[0016] According to one aspect of the present invention, the structure of the passive waveguide layer includes any one of a rectangular waveguide, a trapezoidal waveguide, a slot waveguide, and a ridge waveguide, and the material of the passive waveguide layer includes any one of silicon nitride, silicon oxide, lithium niobate, and silicon.

[0017] According to one aspect of the invention, the material of said covering layer includes any one of silicon oxide, silicon nitride, silicon, hydrogen silsesquioxane polymer, and polymethyl methacrylate.

[0018] According to one aspect of the invention, the material of said buffer layer includes any one of silicon nitride, silicon oxide, lithium niobate, and silicon.

[0019] According to one aspect of the present invention, the passive waveguide layer has a thickness of 50-500 nm and a width of 500-5000 nm; the doped layer has a thickness of 100-600 nm; and the buffer layer has a thickness of 1-100 nm.

[0020] According to one aspect of the present invention, wherein m = 0 and n = 3, the multilayer doped layer includes a first doped layer, a second doped layer and a third doped layer, wherein the thickness of the first doped layer is 330-380 nm, preferably 360 nm; the thickness of the second doped layer is 400-500 nm, preferably 450 nm; and the thickness of the third doped layer is 420-470 nm, preferably 450 nm.

[0021] According to one aspect of the present invention, wherein m = 2 and n = 0, the multilayer doped layer includes a first doped layer and a second doped layer, wherein the thickness of the first doped layer is 440-470 nm, preferably 460 nm; and the thickness of the second doped layer is 450-460 nm, preferably 450 nm.

[0022] According to one aspect of the invention, the materials of the first doped layer, the second doped layer and the third doped layer comprise aluminum oxide, wherein the material is doped with ions of any one of erbium, ytterbium, neodymium, praseodymium, thulium and holmium.

[0023] According to one aspect of the invention, the materials of the first doped layer and the second doped layer comprise aluminum oxide, wherein the dopant is ion selected from erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

[0024] According to one aspect of the invention, wherein m = 1, n = 1, the multilayer doped layer includes a first doped layer and a second doped layer, the material of the first doped layer includes aluminum oxide and is doped with thulium ions, and the material of the second doped layer includes aluminum oxide and is doped with erbium ions.

[0025] According to one aspect of the present invention, the present invention also relates to a method for fabricating an optical waveguide amplifier, comprising:

[0026] S101: An insulating layer is stacked and formed on the substrate layer;

[0027] S102: A passive waveguide layer and multiple doped layers are stacked on the insulating layer, wherein an m-layer doped layer is disposed above the passive waveguide layer, and an n-layer doped layer is disposed below the passive waveguide layer, where m and n are integers, m+n≥2, and m≥0, n≥0.

[0028] The multilayer doped layer is doped with a variety of rare earth ions.

[0029] According to one aspect of the present invention, the preparation method further includes: forming a capping layer, preferably formed by one of atomic layer deposition, chemical vapor deposition, and physical vapor deposition, wherein m = 0, n ≥ 2, and the capping layer is formed on the passive waveguide layer; or m ≥ 1, n ≥ 1, and the capping layer is disposed on the uppermost doped layer; or m ≥ 2, n = 0, and the capping layer is disposed on the uppermost doped layer, wherein the passive waveguide layer is adjacent to the insulating layer.

[0030] According to one aspect of the present invention, the preparation method further includes: forming a buffer layer between adjacent doped layers, preferably formed by one or more of atomic layer deposition, plasma-enhanced chemical vapor deposition, and low-pressure chemical vapor deposition, wherein the material of the buffer layer includes any one of silicon nitride, silicon oxide, lithium niobate, and silicon.

[0031] According to one aspect of the present invention, step S102 includes: forming the passive waveguide layer by one of atomic layer deposition, plasma-enhanced chemical vapor deposition, and low-pressure chemical vapor deposition, wherein the substrate layer is made of any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, and silicon carbide; the insulating layer is made of any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, silicon carbide, and silicon oxide; the doped layer is made of one or more of aluminum oxide, tantalum oxide, silicon nitride, lithium niobate, or titanium oxide; and the rare earth ions include any one or more of erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

[0032] According to one aspect of the present invention, the structure of the passive waveguide layer includes any one of a rectangular waveguide, a trapezoidal waveguide, a slot waveguide, and a ridge waveguide, and the material of the passive waveguide layer includes any one of silicon nitride, silicon oxide, lithium niobate, and silicon, and the material of the capping layer includes any one of silicon oxide, silicon nitride, silicon, hydrogen silsesquioxane polymer, and polymethyl methacrylate.

[0033] According to one aspect of the present invention, the passive waveguide layer has a thickness of 50-500 nm and a width of 500-5000 nm; the doped layer has a thickness of 100-600 nm; and the buffer layer has a thickness of 1-100 nm.

[0034] According to one aspect of the present invention, wherein m = 0 and n = 3, the multilayer doped layer comprises a first doped layer, a second doped layer and a third doped layer, wherein the thickness of the first doped layer is 330-380 nm, preferably 360 nm; the thickness of the second doped layer is 400-500 nm, preferably 450 nm; and the thickness of the third doped layer is 420-470 nm, preferably 450 nm; the material of the first doped layer, the second doped layer and the third doped layer comprises alumina, wherein it is doped with ions selected from erbium, ytterbium, neodymium, praseodymium, thulium and holmium.

[0035] According to one aspect of the present invention, wherein m = 2 and n = 0, the multilayer doped layer includes a first doped layer and a second doped layer, wherein the thickness of the first doped layer is 440-470 nm, preferably 460 nm; the thickness of the second doped layer is 450-460 nm, preferably 450 nm; the material of the first doped layer and the second doped layer includes alumina, wherein it is doped with ions of any one of erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

[0036] According to one aspect of the invention, wherein m = 1, n = 1, the multilayer doped layer includes a first doped layer and a second doped layer, the material of the first doped layer includes aluminum oxide and is doped with thulium ions, and the material of the second doped layer includes aluminum oxide and is doped with erbium ions.

[0037] Compared with existing technologies, embodiments of the present invention provide an optical waveguide amplifier. Compared with fiber amplifiers doped with rare earth elements, the optical waveguide amplifier in this embodiment is smaller in size, which helps to simplify the device structure, reduce the device size, and lower costs. Compared with existing on-chip optical waveguide amplifiers, the optical waveguide amplifier in this embodiment can be doped with various rare earth ions, enabling it to amplify broadband signals and has a wider range of applications.

[0038] This invention also relates to a method for fabricating an optical waveguide amplifier, which can be used to fabricate an optical waveguide amplifier. Multiple doped layers are disposed above and / or below an unwired waveguide layer, and various rare earth ions are doped in the doped layers. The optical waveguide amplifier obtained can be used to amplify broadband signals and has a wide range of applications. Attached Figure Description

[0039] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0040] Figure 1 A cross-sectional schematic diagram of an optical waveguide amplifier is shown in some embodiments of the present invention;

[0041] Figure 2A and Figure 2B It shows Figure 1 The optical field distribution diagrams of the TE mode (transverse electric mode) and TM mode (transverse magnetic mode) of the optical waveguide amplifier shown in the figure;

[0042] Figures 3A-3C It shows Figure 1 The diagram shows the relationship between the overlap integral factors of the TE mode and TM mode of the optical waveguide amplifier shown in the diagram and their difference with different doped layer thicknesses.

[0043] Figure 4 A cross-sectional schematic diagram of an optical waveguide amplifier is shown in some other embodiments of the present invention;

[0044] Figure 5A and Figure 5B It shows Figure 4 The optical field distribution diagrams of the TE mode and TM mode of the optical waveguide amplifier shown in the figure;

[0045] Figure 6A and Figure 6B It shows Figure 4 The diagram shows the relationship between the overlap integral factors of the TE mode and TM mode of the optical waveguide amplifier shown in the diagram and their difference with different doped layer thicknesses.

[0046] Figure 7 A cross-sectional schematic diagram of an optical waveguide amplifier is shown in some other embodiments of the present invention;

[0047] Figure 8 The present invention is shown Figure 4 The graph shows the gain effect of the optical waveguide amplifier on lasers of different wavelengths.

[0048] Figure 9 A schematic flowchart of the fabrication method of the optical waveguide amplifier in some embodiments of the present invention is shown;

[0049] Figure 10 The diagram illustrates a process flow diagram of a preparation method for forming a cover layer and a buffer layer in some embodiments of the present invention. Detailed Implementation

[0050] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0051] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," 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 invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "coupling" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0054] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0055] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0056] Figure 1 A cross-sectional schematic diagram of the optical waveguide amplifier 100 in some embodiments of the present invention is shown. See also: Figure 1 In some embodiments of the present invention, the optical waveguide amplifier 100 includes a substrate layer 110, an insulating layer 120, an unswitched waveguide layer 130, and a multilayer doped layer 140.

[0057] The substrate 110 may be made of any one of the following materials: elemental silicon, sapphire, lithium niobate, or compound semiconductors. In some embodiments, the substrate 110 may be made of a multilayered structure, and the materials of different layers may be the same or different.

[0058] An insulating layer 120 is stacked on the substrate layer 110, for example, an insulating layer 130 is deposited on the substrate layer 110. The insulating layer 120 can isolate the substrate layer 110 from the passive waveguide layer 130 and the doped layer 140, thereby reducing the risk of optical field leakage from the passive waveguide layer 130 and the doped layer 140 into the substrate layer 110. In some embodiments, the material of the insulating layer 120 is, for example, the same as the material of the substrate layer 110, or the material of the insulating layer 120 includes silicon oxide.

[0059] A non-switched waveguide layer 130 and multiple doped layers 140 are stacked on an insulating layer 120. Specifically, m doped layers are disposed above the non-switched waveguide layer 130 (on the side away from the insulating layer 120), and n doped layers are disposed below the non-switched waveguide layer 130 (on the side closer to the insulating layer 120). Here, m and n are both integers and satisfy the following inequality:

[0060] m+n≥2, and m≥0, n≥0.

[0061] In other words, the optical waveguide amplifier 100 in this embodiment may include multiple doped layers 140 located above the unstable waveguide layer 130, multiple doped layers 140 located below the unstable waveguide layer 130, and at least one doped layer 140 located above the unstable waveguide layer 130 and at least one doped layer 140 located below the unstable waveguide layer 130.

[0062] Specifically, when m = 0 and n ≥ 2, the unswitched waveguide layer 130 is located above the doped layer 140. When n = 0 and m ≥ 2, the unswitched waveguide layer 130 is adjacent to the insulating layer 120. When m ≥ 1 and n ≥ 1, the unswitched waveguide layer 130 is located between the multiple doped layers 140.

[0063] In this embodiment, the passive waveguide layer 130 can be shaped like a rectangular waveguide, trapezoidal waveguide, slot waveguide, ridge waveguide, etc. In embodiments of the present invention, the specific shape and size of the passive waveguide layer 130 are not limited, and can be pre-designed according to actual needs, such as the wavelength range of the optical signal. In some embodiments, the material of the passive waveguide layer 130 includes one or more of silicon oxide, silicon nitride, silicon, hydrogen silsesquioxane polymer, and polymethyl methacrylate. The material of the passive waveguide layer 130 can also be determined according to actual usage requirements. In some embodiments, the thickness of the passive waveguide layer 130 is 50-500 nm, and the width is 500-5000 nm. Preferably, the thickness of the unswitched waveguide layer 130 is, for example, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc., and the width of the unswitched waveguide layer 130 is 500nm, 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, 3500nm, 4000nm, 4500nm, 5000nm, etc.

[0064] In this embodiment, the multilayer doped layer 140 is doped with various rare earth ions. The material of the doped layer 140 may include one or more of alumina, tantalum oxide, silicon nitride, lithium niobate, or titanium oxide, and rare earth ions are doped into the material of the doped layer 140. The rare earth ions include one or more of erbium, ytterbium, neodymium, praseodymium, thulium, and holmium. In some embodiments, the thickness of the doped layer 140 is 100-600 nm, preferably, for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, or 600 nm.

[0065] Different rare earth ions amplify optical signals in different wavelength bands. According to a preferred embodiment of the present invention, by doping with multiple rare earth ions at an optimal concentration, the optical waveguide amplifier 100 can amplify optical signals in different wavelength ranges, thus improving its applicability. Furthermore, by adjusting the pump power, the optical waveguide amplifier 100 can achieve a more balanced amplification effect across the entire spectrum.

[0066] The optical waveguide amplifier 100 in this embodiment, through waveguide structure design, can achieve a larger mode field area, thereby reducing instability caused by nonlinear effects of high-power pump light, and helping to increase signal power or energy by increasing gain saturation power. Furthermore, the optical waveguide amplifier 100 can also increase the optical field overlap factor between the optical signal and the doped layer 140, contributing to improved optical signal gain.

[0067] According to a preferred embodiment of the present invention, the optical waveguide amplifier further includes a capping layer. Wherein, when there is no doped layer above the unswitched waveguide layer (i.e., m = 0, n ≥ 2), the capping layer is stacked above the unswitched waveguide layer. When at least one doped layer is disposed above the unswitched waveguide layer (i.e., m ≥ 1), the capping layer is stacked on the uppermost doped layer.

[0068] In some embodiments, when there is no doped layer below the uninsulated waveguide layer, i.e., n = 0 and m ≥ 2, the capping layer is stacked on the uppermost doped layer, and the uninsulated waveguide layer is adjacent to the insulating layer.

[0069] The capping layer can protect the doped layer or the unswitched waveguide layer, thereby improving the lifespan of the optical waveguide amplifier. Furthermore, by adjusting the material of the capping layer, transmission loss of the optical signal can be reduced.

[0070] In a preferred embodiment of the present invention, the optical waveguide amplifier 100 further includes a buffer layer 150. The buffer layer 150 is disposed between adjacent doped layers 140. For example... Figure 1 As shown, in some embodiments, the optical waveguide amplifier 100 includes three doped layers 140 located below the unwired waveguide layer 130, and the optical waveguide amplifier 100 also includes two buffer layers 150, which are respectively disposed between the three doped layers 140.

[0071] In this embodiment, a buffer layer 150 is disposed between one doped layer 140 and another doped layer 140. When multiple doped layers 140 are included above or below the unswitched waveguide layer 130, a buffer layer 150 can be disposed between adjacent doped layers 140. In some embodiments, if there is only one doped layer 140 above or below the unswitched waveguide layer 130, a buffer layer 150 may not be provided.

[0072] The material of the buffer layer 150 includes one or more of silicon nitride, silicon oxide, lithium niobate, and silicon. In some embodiments, the thickness of the buffer layer 150 is 1-100 nm, preferably, for example, 1 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, etc.

[0073] According to some embodiments of the present invention, such as Figure 1 As shown, the optical waveguide amplifier 100 includes three doped layers 140, and the three doped layers 140 are stacked below the uninsulated waveguide layer 130, i.e., m=0, n=3. For ease of description, the three doped layers 140, from bottom to top (from the insulating layer 120 upwards), include a first doped layer 141, a second doped layer 142, and a third doped layer 143.

[0074] An unstable waveguide layer 130 is formed above the third doped layer 143, and the material of the unstable waveguide layer 130 includes silicon oxide. The unstable waveguide layer 130 has a thickness of 200 nm and a width of 4000 nm.

[0075] Furthermore, a first buffer layer 151 is disposed between the first doped layer 141 and the second doped layer 142, and a second buffer layer 152 is disposed between the second doped layer 142 and the third doped layer 143. The thickness of the first buffer layer 151 and the second buffer layer 152 is 30 nm.

[0076] Specifically, in this embodiment, the optical waveguide amplifier 100 has, from the substrate layer 110 upwards, an insulating layer 120, a first doped layer 141, a first buffer layer 151, a second doped layer 142, a second buffer layer 152, a third doped layer 143, and a non-switching waveguide layer 130. The insulating layer 120 is made of silicon oxide. The first doped layer 141, the second doped layer 142, and the third doped layer 143 are made of aluminum oxide, doped with any one of the rare earth ions selected from erbium, ytterbium, neodymium, praseodymium, thulium, and holmium. The first buffer layer 151 and the second buffer layer 152 are made of silicon nitride.

[0077] After fabricating the optical waveguide amplifier 100 in this embodiment, actual measurements were performed on different layers in the optical waveguide amplifier 100 to determine that the refractive index of the insulating layer 120 is 1.44, the refractive index of the first doped layer 141 is 1.62, the refractive index of the first buffer layer 151 is 2.03, the refractive index of the second doped layer 142 is 1.62, the refractive index of the second buffer layer 152 is 2.03, the refractive index of the third doped layer 143 is 1.62, and the refractive index of the unwired waveguide layer 130 is 1.44.

[0078] In practical applications of the optical waveguide amplifier 100, the different polarization states of the signal light and the overlapping distribution of the pump light affect the gain performance of the optical waveguide amplifier 100. A corrected overlap integral factor is used to detect the gain performance under different polarization states. The corrected overlap integral factor Γ′ is... s The overlap factor Γ between the signal light and the concentration distribution of doped rare earth ions is expressed as... s The normalized overlap factor Γ of the intensity distributions of pump light and signal light sp The product of.

[0079] The optical field of the optical waveguide amplifier 100 was simulated using finite element method (FEM) software. The optical field distribution of the TE mode is shown below. Figure 2A As shown, the light field distribution of the TM mode is as follows: Figure 2B As shown.

[0080] Through simulation, the overlap integral factors of the TE mode and TM mode, as well as the difference between the overlap integral factors of the TE mode and TM mode, and their relationship with the thickness of the first doped layer 141 are determined as follows: Figure 3A As shown. The overlap integration factors of the TE mode and TM mode, and the difference between the overlap integration factors of the TE mode and TM mode, are determined, and their relationship with the thickness of the second doped layer 142 is as follows. Figure 3B As shown. The overlap integration factors of the TE mode and TM mode, and the difference between the overlap integration factors of the TE mode and TM mode, are determined, and their relationship with the thickness of the third doped layer 143 is shown in the figure. Figure 3C As shown.

[0081] according to Figures 3A-3C When the thickness of the first doped layer 141 is between 330-380 nm, the thickness of the second doped layer 142 is between 400-500 nm, and the thickness of the third doped layer 143 is between 420-470 nm, the absolute value of the difference between the overlap integral factors of the corrected TE mode and TM mode is less than 0.002, and the optical waveguide amplifier is insensitive to the polarization of the optical signal.

[0082] Specifically, in some embodiments of the present invention, the thickness of the first doped layer 141 is 330-380nm, for example, the thickness of the first doped layer 141 is 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, etc., and preferably, the thickness of the first doped layer 141 is 360nm.

[0083] The thickness of the second doped layer 142 is 400-500nm, for example, the thickness of the second doped layer 142 is 400nm, 410nm, 420nm, 430nm, 440nm, 450nm, 460nm, 470nm, 480nm, 490nm, 500nm, etc., and preferably, the thickness of the second doped layer 142 is 450nm.

[0084] The thickness of the third doped layer 143 is 420-470nm, for example, the thickness of the third doped layer 143 is 420nm, 430nm, 440nm, 450nm, 460nm, 470nm, etc., and preferably, the thickness of the third doped layer 143 is 450nm.

[0085] When the thickness of the first doped layer 141 is 360 nm, the thickness of the second doped layer 142 is 450 nm, and the thickness of the third doped layer 143 is 450 nm, the corrected TE mode and TM mode overlap integral factors are 0.8746 and 0.8747, respectively.

[0086] In contrast, in some comparative examples, erbium-doped alumina was deposited on a passive silicon nitride ridge waveguide [Nature Communications, 2019, 10(1)], and the overlap factor of this structure was 0.32. Alternatively, erbium-doped tellurium oxide was deposited on a passive silicon nitride rectangular waveguide [Photonics Research, 2020, 8(2)], and the overlap factor of this structure was 0.6. Therefore, the optical waveguide amplifier 100 provided in this embodiment has a higher overlap factor, which can effectively improve the gain of the optical signal.

[0087] Figure 4 The structure of an optical waveguide amplifier 200 according to another embodiment of the present invention is shown. (See reference) Figure 4 The optical waveguide amplifier 200 includes two doped layers 240, and both doped layers 240 are stacked on top of the unswitched waveguide layer 230, i.e., n=0, m=2. For ease of description, the two doped layers 240 are, from bottom to top (from the unswitched waveguide layer 230 upwards), a first doped layer 241 and a second doped layer 242.

[0088] An insulating layer 220 is formed above a substrate layer 210. A non-switched waveguide layer 230 is formed above an insulating layer 220. The non-switched waveguide layer 230 has a thickness of 80 nm and a width of 2500 nm.

[0089] Furthermore, a buffer layer 250 is disposed between the first doped layer 241 and the second doped layer 242. Specifically, in this embodiment, the substrate layer 210 of the optical waveguide amplifier 200 consists of, sequentially upwards, an insulating layer 220, a non-switching waveguide layer 230, a first doped layer 241, a buffer layer 250, and a second doped layer 242. The materials of the first doped layer 241 and the second doped layer 242 include alumina, wherein it is doped with any one of rare earth ions selected from erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

[0090] The optical field of the optical waveguide amplifier 200 was simulated using finite element method (FEM) software. The optical field distribution of the TE mode is shown below. Figure 5A As shown, the light field distribution of the TM mode is as follows: Figure 5BAs shown.

[0091] Through simulation, the overlap integral factors of the TE mode and TM mode, as well as the difference between the overlap integral factors of the TE mode and TM mode, and their relationship with the thickness of the first doped layer 241 are determined as follows: Figure 6A As shown. The overlap integration factors of the TE mode and TM mode, and the difference between the overlap integration factors of the TE mode and TM mode, are determined, and their relationship with the thickness of the second doped layer 242 is as follows. Figure 6B As shown.

[0092] according to Figure 6A and Figure 6B When the thickness of the first doped layer 241 is between 440-470 nm and the thickness of the second doped layer 242 is between 450-460 nm, the absolute value of the difference between the overlap integral factors of the corrected TE mode and TM mode is less than 0.002, and the optical waveguide amplifier is insensitive to the polarization of the optical signal.

[0093] Specifically, in some embodiments of the present invention, the thickness of the first doped layer 241 is 440-470nm, for example, the thickness of the first doped layer 241 is 440nm, 450nm, 460nm, 470nm, etc., and preferably, the thickness of the first doped layer 241 is 460nm.

[0094] The thickness of the second doped layer 242 is 450-460nm, for example, the thickness of the second doped layer 242 is 450nm, 455nm, 460nm, etc., preferably, the thickness of the second doped layer 242 is 450nm.

[0095] When the thickness of the first doped layer 241 is 460 nm and the thickness of the second doped layer 242 is 450 nm, the corrected overlap integral factors of the TE mode and TM mode are 0.7174 and 0.7168, respectively.

[0096] As can be seen from the comparison with the aforementioned comparative examples, the optical waveguide amplifier 200 provided in this embodiment also has a higher overlap factor, which can effectively improve the gain effect of the optical signal.

[0097] Figure 7 The structure of an optical waveguide amplifier 300 according to another embodiment of the present invention is shown. (Reference) Figure 7 In this embodiment, the optical waveguide amplifier 300 includes two doped layers 340, one of which is disposed above the unswitched waveguide layer 330 and the other is disposed below the unswitched waveguide layer 330, i.e., m=1 and n=1 in this embodiment.

[0098] like Figure 7 As shown, according to a preferred embodiment of the present invention, the optical waveguide amplifier 300 further includes a cover layer 350.

[0099] In this embodiment, the optical waveguide amplifier 300 includes, from bottom to top, a substrate layer 310, an insulating layer 320, a first doped layer 341, an unswitched waveguide layer 330, a second doped layer 342, and a capping layer 350.

[0100] The capping layer 350 can protect the doped layer 340 or the unswitched waveguide layer 330, thereby improving the lifespan of the optical waveguide amplifier 300. Furthermore, by adjusting the material of the capping layer 350, the transmission loss of optical signals can also be reduced.

[0101] In this embodiment of the optical waveguide amplifier 300, the materials of the substrate layer 310, the insulating layer 320, and the passive waveguide layer 330 are similar to those of the substrate layer 110, the insulating layer 120, and the passive waveguide layer 130 in the optical waveguide amplifier 100 of the previous embodiment, and will not be described again. The passive waveguide layer has a thickness of 80 nm and a width of 1500 nm.

[0102] In this embodiment, the first doped layer 341 is made of aluminum oxide and doped with thulium ions, with a thickness of 500 nm. The second doped layer 342 is made of aluminum oxide and doped with erbium ions, with a thickness of 500 nm.

[0103] Figure 8 The figure shows the gain simulation curves of 790nm and 980nm wavelength lasers as thulium-doped and erbium-doped material pump sources, respectively. Figure 8 It can be seen that when lasers with wavelengths of 790nm and 980nm are selected as pump sources, the optical waveguide amplifier 300 in this embodiment has a high gain effect in the wavelength range of 1440-1580nm. The optical waveguide amplifier 300 in this embodiment can amplify broadband signals.

[0104] like Figure 9 As shown, the present invention also relates to a method S100 for fabricating an optical waveguide amplifier. Method S100 is used to fabricate an optical waveguide amplifier; preferably, method S100 is used to fabricate the optical waveguide amplifier as described in the foregoing embodiments.

[0105] See Figure 9In step S101, an insulating layer is stacked and formed on the substrate. For example, a substrate is provided, and an insulating layer is deposited on the substrate. According to some embodiments of the present invention, the material of the substrate may include any one of elemental silicon, sapphire, lithium niobate, gallium nitride, and silicon carbide. The material of the insulating layer may be the same as the material of the substrate, for example, including any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, and silicon carbide, or it may include silicon oxide. According to a preferred embodiment of the present invention, the insulating layer may be deposited on the substrate by vacuum deposition. The insulating layer can reduce the electromagnetic interference of electrical signals on optical signals, which is beneficial to improving the stability and transmission efficiency of optical signals.

[0106] In step S102, a non-switched waveguide layer and multiple doped layers are stacked on an insulating layer. Specifically, m doped layers are disposed above the non-switched waveguide layer (on the side furthest from the insulating layer), and n doped layers are disposed below the non-switched waveguide layer (on the side closest to the insulating layer). Here, m and n are both integers and satisfy the following inequality:

[0107] m+n≥2, and m≥0, n≥0.

[0108] In other words, the optical waveguide amplifier prepared in this embodiment may include multiple doped layers located above the unswitched waveguide layer, multiple doped layers located below the unswitched waveguide layer, and at least one doped layer located above the unswitched waveguide layer and at least one doped layer located below the unswitched waveguide layer.

[0109] In this embodiment, the non-switched waveguide layer and the multilayer doped layers are stacked on the insulating layer, meaning that the non-switched waveguide layer and the multilayer doped layers are formed sequentially layer by layer. That is, in this embodiment, n doped layers are formed sequentially on the insulating layer, then a non-switched waveguide layer is formed on the n doped layers, and then m doped layers are formed on the non-switched waveguide layer.

[0110] The passive waveguide layer can be formed above the insulating layer or the doped layer using one of the following methods: atomic layer deposition, plasma-enhanced chemical vapor deposition, or low-pressure chemical vapor deposition. In some embodiments, the passive waveguide layer structure can include any one of a rectangular waveguide, a trapezoidal waveguide, a groove waveguide, or a ridge waveguide. The material of the passive waveguide layer includes any one of silicon nitride, silicon oxide, lithium niobate, or silicon. In some embodiments, the passive waveguide layer has a thickness of 50-500 nm and a width of 500-5000 nm. Preferably, the thickness of the unswitched waveguide layer is, for example, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc., and the width of the unswitched waveguide layer 130 is 500nm, 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, 3500nm, 4000nm, 4500nm, 5000nm, etc.

[0111] In this embodiment, the multilayer doped layer is doped with various rare earth ions. The material of the doped layer may include one or more of alumina, tantalum oxide, silicon nitride, lithium niobate, or titanium oxide, and rare earth ions are doped into the material of the doped layer. In some embodiments, the rare earth ions include one or more of erbium, ytterbium, neodymium, praseodymium, thulium, and holmium. Preferably, the doped layer can be formed by one or more methods selected from atomic layer deposition, magnetron sputtering, and ion implantation. In some embodiments, the thickness of the doped layer is 100-600 nm, preferably, for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, or 600 nm.

[0112] Figure 10 The flowchart of method S200 for fabricating an optical waveguide amplifier according to a preferred embodiment of the present invention is shown. See also Figure 10 Steps S201 and S202 in preparation method S200 are essentially the same as steps S101 and S102 in preparation method S100 in the aforementioned embodiments, and will not be described again. Preparation method S200 includes the process of preparing a capping layer and a buffer layer, which will be described below in conjunction with... Figure 10 The preparation method S200 is explained.

[0113] In step S203, a capping layer is formed. Preferably, the capping layer can be formed by atomic layer deposition, chemical vapor deposition, or physical vapor deposition. According to a preferred embodiment of the invention, the material of the capping layer includes any one of silicon oxide, silicon nitride, silicon, hydrogen silsesquioxane polymer, and polymethyl methacrylate.

[0114] In different embodiments, the capping layer is located on the unswitched waveguide layer or on the doped layer. The capping layer can protect the doped or unswitched waveguide layer, improving the lifespan of the optical waveguide amplifier. Furthermore, by adjusting the material of the capping layer, transmission loss of optical signals can be reduced.

[0115] Specifically, in some embodiments, when there is no doped layer above the unswitched waveguide layer (i.e., m = 0, n ≥ 2), a capping layer is stacked on top of the unswitched waveguide layer. When at least one doped layer is disposed above the unswitched waveguide layer (i.e., m ≥ 1), a capping layer is stacked on the uppermost doped layer. In some embodiments, when there is no doped layer below the unswitched waveguide layer (i.e., n = 0, m ≥ 2), a capping layer is stacked on the uppermost doped layer, and the unswitched waveguide layer is adjacent to the insulating layer.

[0116] The present invention also includes S204, forming a buffer layer between adjacent doped layers. The optical waveguide amplifier fabricated in this invention comprises a multilayered structure, and in actual fabrication, multiple different layered structures are sequentially formed starting from the substrate layer. Therefore, as... Figure 10 As shown, a first doped layer is formed above the insulating layer (in some embodiments, there may be no doped layer below the unwired waveguide layer, i.e., n=0). A first buffer layer is formed above the first doped layer (in some embodiments, when n=0 or n=1, a buffer layer is not required below the unwired waveguide layer). After forming n doped layers and n-1 buffer layers above the insulating layer, an unwired waveguide layer is formed above the doped layers. Then, m doped layers and m-1 buffer layers are sequentially formed at intervals above the unwired waveguide layer. Finally, a capping layer is formed above the uppermost doped layer (in some embodiments, if there is no uppermost doped layer, it is on the unwired waveguide layer).

[0117] In some embodiments, the optical waveguide amplifier does not include a doped layer located above the unswitched waveguide layer. In this case, a capping layer can be formed above the unswitched waveguide layer after its formation. In some embodiments, the optical waveguide amplifier does not include a capping layer, for example... Figure 1 and Figure 4 The optical waveguide amplifier shown in this example can be fabricated by terminating the fabrication process after the formation of the unswitched waveguide layer or the topmost doped layer.

[0118] Furthermore, according to a preferred embodiment of the present invention, the buffer layer can be formed by one or more of atomic layer deposition, plasma-enhanced chemical vapor deposition, and low-pressure chemical vapor deposition. The material of the buffer layer may include any one of silicon nitride, silicon oxide, lithium niobate, and silicon. In some embodiments, the thickness of the buffer layer is 1-100 nm, preferably, for example, the thickness of the buffer layer 150 is 1 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, etc.

[0119] According to a specific embodiment of the present invention, the method for fabricating an optical waveguide amplifier is used to fabricate an optical waveguide amplifier with m=0 and n=3, that is, having three doped layers below the unswitched waveguide layer and no doped layer above the unswitched waveguide layer, for example, for fabricating... Figure 1 The optical waveguide amplifier 100 shown is, for ease of description, comprised of three doped layers from bottom to top (from the insulating layer upwards): a first doped layer, a second doped layer, and a third doped layer. Further, a first buffer layer is formed between the first and second doped layers, and a second buffer layer is formed between the second and third doped layers. The optical waveguide amplifier, from the substrate layer upwards, consists of an insulating layer, a first doped layer, a first buffer layer, a second doped layer, a second buffer layer, a third doped layer, and a non-switching waveguide layer.

[0120] According to this embodiment, after providing a substrate layer, an insulating layer is formed on the substrate layer. A first doped layer is formed on the insulating layer, wherein the material of the first doped layer includes alumina, and is doped with ions selected from erbium, ytterbium, neodymium, praseodymium, thulium, and holmium. Specifically, the first doped layer can be deposited on the surface of the insulating layer using atomic layer deposition technology. Er(thd)3 and ozone are selected as precursors for preparing erbium oxide thin films; trimethylaluminum (TMA) and water are selected as precursors for preparing alumina thin films; nitrogen is selected as the transport and purging gas; and the sample obtained in the above steps is subjected to post-annealing treatment in an argon atmosphere at 650℃-850℃.

[0121] A first buffer layer is formed above the first doped layer. Specifically, the first buffer layer is grown by low-pressure chemical vapor deposition. The material of the first buffer layer can be silicon nitride, and the thickness can be 30 nm.

[0122] A second doped layer is formed on top of the first buffer layer. Specifically, the second doped layer can be formed using the steps described above for forming the first doped layer.

[0123] A second buffer layer is formed above the second doped layer. Specifically, the second buffer layer is grown by low-pressure chemical vapor deposition. The material of the second buffer layer can be silicon nitride, and the thickness can be 30 nm.

[0124] A third doped layer is formed above the second buffer layer. Specifically, the third doped layer can be formed using the steps described above for forming the first doped layer.

[0125] A passive waveguide layer is formed above the third doped layer. Specifically, a silicon nitride thin film is deposited on the surface of the third doped layer using chemical vapor deposition to serve as the passive waveguide layer. The thickness of the passive waveguide layer can be 200 nm. Furthermore, the passive waveguide layer can be photolithographically or etched to prepare a rectangular structure with a width of 4000 nm.

[0126] According to a preferred embodiment of the present invention, the thickness of the first doped layer is 330-380 nm, for example, the thickness of the first doped layer is 330 nm, 340 nm, 350 nm, 360 nm, 370 nm, 380 nm, etc., and preferably, the thickness of the first doped layer is 360 nm.

[0127] The thickness of the second doped layer is 400-500nm, for example, the thickness of the second doped layer is 400nm, 410nm, 420nm, 430nm, 440nm, 450nm, 460nm, 470nm, 480nm, 490nm, 500nm, etc., and preferably, the thickness of the second doped layer is 450nm.

[0128] The thickness of the third doped layer is 420-470nm, for example, the thickness of the third doped layer is 420nm, 430nm, 440nm, 450nm, 460nm, 470nm, etc., and preferably, the thickness of the third doped layer is 450nm.

[0129] When the thickness of the first doped layer is 360 nm, the thickness of the second doped layer is 450 nm, and the thickness of the third doped layer is 450 nm, the overlap integral factors of the corrected TE mode and TM mode of the prepared optical waveguide amplifier are 0.8746 and 0.8747, respectively, which can effectively improve the gain of the optical signal.

[0130] According to another embodiment of the present invention, the method for fabricating an optical waveguide amplifier is used to fabricate an optical waveguide amplifier with m=2 and n=0, that is, having two doped layers above the unswitched waveguide layer and no doped layer below the unswitched waveguide layer, for example, for fabricating... Figure 4 The optical waveguide amplifier 200 shown is illustrated. For ease of description, the two doped layers, from bottom to top (from the unswitched waveguide layer upwards), consist of a first doped layer and a second doped layer, respectively.

[0131] A buffer layer can be formed between the first doped layer and the second doped layer. The preparation process and materials of the first doped layer, the second doped layer, and the buffer layer in this embodiment can be similar to those in the previous embodiments.

[0132] Specifically, the thickness of the first doped layer is 440-470nm, for example, the thickness of the first doped layer is 440nm, 450nm, 460nm, 470nm, etc., and preferably, the thickness of the first doped layer is 460nm.

[0133] The thickness of the second doped layer is 450-460 nm, for example, the thickness of the second doped layer is 450 nm, 455 nm, 460 nm, etc., and preferably, the thickness of the second doped layer is 450 nm.

[0134] When the thickness of the first doped layer is 460 nm and the thickness of the second doped layer is 450 nm, the overlap integral factors of the corrected TE mode and TM mode of the optical waveguide amplifier prepared in this embodiment are 0.7174 and 0.7168, respectively.

[0135] According to another embodiment of the present invention, the method for fabricating an optical waveguide amplifier is used to fabricate an optical waveguide amplifier with m=1 and n=1, that is, having a doped layer above the unswitched waveguide layer and a doped layer below the unswitched waveguide layer, for example, for fabricating... Figure 7 The optical waveguide amplifier 300 shown is illustrated. For ease of description, the doped layer below the unswitched waveguide layer is the first doped layer, and the doped layer above the unswitched waveguide layer is the second doped layer. The optical waveguide amplifier comprises, from bottom to top, a substrate layer, an insulating layer, a first doped layer, an unswitched waveguide layer, and a second doped layer.

[0136] The first doped layer is made of aluminum oxide doped with thulium ions, and the second doped layer is made of aluminum oxide doped with erbium ions. When lasers with wavelengths of 790 nm and 980 nm are selected as pump sources, the optical waveguide amplifier prepared in this embodiment exhibits high gain in the wavelength range of 1440-1580 nm, and can amplify broadband signals.

[0137] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An optical waveguide amplifier, comprising: Substrate layer; An insulating layer is stacked on the substrate layer; A passive waveguide layer and multiple doped layers are stacked on the insulating layer; The passive waveguide layer is provided with m doped layers above it and n doped layers are provided below it, where m and n are integers, m+n≥2, and m≥0, n≥0; The multilayer doped layer is doped with a variety of rare earth ions.

2. The optical waveguide amplifier according to claim 1 further includes a cover layer, wherein m = 0, n ≥ 2, and the cover layer is disposed on the passive waveguide layer; or m ≥ 1, n ≥ 1, and the cover layer is disposed on the uppermost doped layer; or m ≥ 2, n = 0, and the cover layer is disposed on the uppermost doped layer, wherein the passive waveguide layer is adjacent to the insulating layer.

3. The optical waveguide amplifier according to claim 1 further includes buffer layers disposed between adjacent doped layers.

4. The optical waveguide amplifier according to claim 1, wherein the substrate layer is made of any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, and silicon carbide; the insulating layer is made of any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, silicon carbide, and silicon oxide; the doped layer is made of one or more of aluminum oxide, tantalum oxide, silicon nitride, lithium niobate, or titanium oxide; and the rare earth ions include any one or more of erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

5. The optical waveguide amplifier according to claim 1 or 2, wherein the structure of the passive waveguide layer includes any one of a rectangular waveguide, a trapezoidal waveguide, a slot waveguide, and a ridge waveguide, and the material of the passive waveguide layer includes any one of silicon nitride, silicon oxide, lithium niobate, and silicon.

6. The optical waveguide amplifier according to claim 2, wherein the material of the covering layer includes any one of silicon oxide, silicon nitride, silicon, hydrogen silsesquioxane polymer, and polymethyl methacrylate.

7. The optical waveguide amplifier according to claim 3, wherein the material of the buffer layer includes any one of silicon nitride, silicon oxide, lithium niobate, and silicon.

8. The optical waveguide amplifier according to claim 3, wherein the thickness of the passive waveguide layer is 50-500 nm and the width is 500-5000 nm; the thickness of the doped layer is 100-600 nm; and the thickness of the buffer layer is 1-100 nm.

9. The optical waveguide amplifier according to claim 3, wherein m = 0, n = 3, the multilayer doped layer includes a first doped layer, a second doped layer and a third doped layer, wherein the thickness of the first doped layer is 330-380 nm, preferably 360 nm; the thickness of the second doped layer is 400-500 nm, preferably 450 nm; and the thickness of the third doped layer is 420-470 nm, preferably 450 nm.

10. The optical waveguide amplifier according to claim 3, wherein m = 2, n = 0, the multilayer doped layer includes a first doped layer and a second doped layer, the thickness of the first doped layer is 440-470 nm, preferably 460 nm; the thickness of the second doped layer is 450-460 nm, preferably 450 nm.

11. The optical waveguide amplifier according to claim 9, wherein the materials of the first doped layer, the second doped layer and the third doped layer comprise aluminum oxide, wherein it is doped with ions of any one of erbium, ytterbium, neodymium, praseodymium, thulium and holmium.

12. The optical waveguide amplifier according to claim 10, wherein the materials of the first doped layer and the second doped layer comprise aluminum oxide, wherein the dopant is ion selected from erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

13. The optical waveguide amplifier according to claim 1, wherein m = 1, n = 1, the multilayer doped layer includes a first doped layer and a second doped layer, the material of the first doped layer includes alumina, wherein thulium ions are doped, and the material of the second doped layer includes alumina, wherein erbium ions are doped.

14. A method for fabricating an optical waveguide amplifier, comprising: S101: An insulating layer is stacked and formed on the substrate layer; S102: A passive waveguide layer and multiple doped layers are stacked on the insulating layer, wherein an m-layer doped layer is disposed above the passive waveguide layer, and an n-layer doped layer is disposed below the passive waveguide layer, where m and n are integers, m+n≥2, and m≥0, n≥0. The multilayer doped layer is doped with a variety of rare earth ions.

15. The preparation method according to claim 14, further comprising: A capping layer is formed, preferably by one of atomic layer deposition, chemical vapor deposition, and physical vapor deposition, wherein m = 0 and n ≥ 2, and the capping layer is formed on the passive waveguide layer. Alternatively, if m ≥ 1 and n ≥ 1, the capping layer is disposed on the uppermost doped layer; or if m ≥ 2 and n = 0, the capping layer is disposed on the uppermost doped layer, and the passive waveguide layer is adjacent to the insulating layer.

16. The preparation method according to claim 14, further comprising: A buffer layer is formed between adjacent doped layers, preferably formed by one or more of atomic layer deposition, plasma-enhanced chemical vapor deposition, and low-pressure chemical vapor deposition. The material of the buffer layer includes any one of silicon nitride, silicon oxide, lithium niobate, and silicon.

17. The preparation method according to claim 14, wherein step S102 comprises: The passive waveguide layer is formed by one of atomic layer deposition, plasma-enhanced chemical vapor deposition, and low-pressure chemical vapor deposition, wherein the substrate layer is made of any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, and silicon carbide; the insulating layer is made of any one of silicon, sapphire, lithium niobate, gallium arsenide, gallium nitride, silicon carbide, and silicon oxide; the doped layer is made of one or more of aluminum oxide, tantalum oxide, silicon nitride, lithium niobate, or titanium oxide; and the rare earth ions include any one or more of erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

18. The preparation method according to claim 15, wherein the structure of the passive waveguide layer includes any one of rectangular waveguide, trapezoidal waveguide, slot waveguide, and ridge waveguide, the material of the passive waveguide layer includes any one of silicon nitride, silicon oxide, lithium niobate, and silicon, and the material of the capping layer includes any one of silicon oxide, silicon nitride, silicon, hydrogen silsesquioxane polymer, and polymethyl methacrylate.

19. The preparation method according to claim 16, wherein the thickness of the passive waveguide layer is 50-500 nm and the width is 500-5000 nm; the thickness of the doped layer is 100-600 nm; and the thickness of the buffer layer is 1-100 nm.

20. The preparation method according to claim 16, wherein m = 0, n = 3, the multilayer doped layer comprises a first doped layer, a second doped layer and a third doped layer, wherein the thickness of the first doped layer is 330-380 nm, preferably 360 nm; the thickness of the second doped layer is 400-500 nm, preferably 450 nm; the thickness of the third doped layer is 420-470 nm, preferably 450 nm; the material of the first doped layer, the second doped layer and the third doped layer comprises alumina, wherein it is doped with ions of any one of erbium, ytterbium, neodymium, praseodymium, thulium and holmium.

21. The preparation method according to claim 16, wherein m = 2, n = 0, the multilayer doped layer includes a first doped layer and a second doped layer, the thickness of the first doped layer is 440-470 nm, preferably 460 nm; the thickness of the second doped layer is 450-460 nm, preferably 450 nm; the material of the first doped layer and the second doped layer includes alumina, wherein it is doped with ions of any one of erbium, ytterbium, neodymium, praseodymium, thulium, and holmium.

22. The preparation method according to claim 14, wherein m = 1, n = 1, the multilayer doped layer includes a first doped layer and a second doped layer, the material of the first doped layer includes alumina, wherein thulium ions are doped, and the material of the second doped layer includes alumina, wherein erbium ions are doped.

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