C-waveband-oriented erbium-doped AlN optical waveguide amplifier and preparation method thereof
By preparing an erbium-doped aluminum nitride optical waveguide structure, the low efficiency and large size problems of existing optical waveguide amplifiers in the 1550nm band are solved, a high-gain and integrated optical waveguide amplifier is achieved, the preparation process is simplified and the luminescence performance of erbium is enhanced.
Patent Information
- Application Number
- CN202510949642.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-10
- Publication Date
- 2025-10-14
AI Technical Summary
Existing optical waveguide amplifiers in the 1550nm band have problems such as limited amplification efficiency, high noise, and large size. In particular, the temperature quenching effect of erbium-doped semiconductor materials leads to low luminescence efficiency.
An erbium-doped aluminum nitride (AlN) optical waveguide structure is used, including a substrate layer, a buried oxide layer, an erbium-doped aluminum nitride waveguide layer and a silicon dioxide cladding layer. Erbium ions are doped by magnetron sputtering or ion implantation to prepare a strip waveguide with a high c-axis orientation. The silicon dioxide cladding is prepared by plasma-enhanced chemical vapor deposition.
The gain capability of the optical waveguide amplifier in the C-band is improved, the thermal quenching effect of erbium is reduced, a large-scale, integrable, high-gain optical waveguide amplifier is realized, the preparation process is simplified and the possibility of co-doping is provided.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of photonic devices, and in particular to a C-band oriented erbium-doped AlN optical waveguide amplifier and a preparation method thereof. Background Art
[0002] In today's optical communications and optoelectronics fields, the demand for high-speed, high-capacity information transmission continues to grow. As a key component, optical waveguide amplifiers play a vital role in boosting optical signal strength and extending transmission distances. The 1550nm band offers unique advantages in optical communications. First, it lies within a low-loss window, effectively reducing signal attenuation during transmission and improving transmission efficiency. Second, the dispersion characteristics of optical fibers in this band are relatively favorable, reducing signal distortion. Furthermore, the 1550nm band offers excellent compatibility with many existing optical communication equipment and systems, facilitating integration and application. With the continuous development and upgrade of optical communication networks, the demand for high-performance optical waveguide amplifiers in the 1550nm band is becoming increasingly urgent. Traditional amplifier technology in this band may face challenges, such as limited amplification efficiency, high noise, and large size. Therefore, the development of new optical waveguide amplifiers for the 1550nm band has become a hot topic of research.
[0003] Currently, research in the field of room-temperature communication-band light sources still faces many challenges. The luminescence of semiconductor materials in the communication band mainly depends on the 4f energy level transition of doped erbium ions.
[0004] According to different optical waveguide media, reported near-infrared optical waveguide amplifiers can be mainly divided into the following categories:
[0005] 1) Optical waveguide amplifiers based on traditional silicon-based materials. Silicon-based materials are commonly used in integrated photonics, offering excellent optical and electrical properties. Current research on silicon-based optical waveguide amplifiers focuses primarily on improving gain performance and reducing loss. Current research focuses on aluminum oxide (Al2O3), silicon nitride (Si3N4), and lithium niobate (LiNbO3). However, aluminum oxide has a low refractive index of ~1.7, resulting in weak light confinement. Gain can only be achieved by depositing it onto a high-refractive-index waveguide core. While silicon nitride has a good refractive index and can achieve waveguide transmission losses as low as 5 dB / m, its low net gain per unit area means that achieving significant gain requires increasing the waveguide length, requiring a large area on the integrated photonic chip. Integrated optical waveguides fabricated using erbium-doped thin-film lithium titanate on insulator (TFLNOI) bonded using photolithography-assisted chemical mechanical etching (PLACE) technology have demonstrated gains as high as 5 dB / cm per unit length, but the fabrication process is complex and expensive.
[0006] 2) Optical waveguide amplifiers based on polymer materials. Polymer materials offer advantages such as low cost, simple manufacturing processes, and ease of processing into devices of various shapes and sizes. Amplifier performance can be optimized by adjusting the polymer composition and structure. However, thermal and mechanical stability under various environmental conditions are relatively poor, and performance may degrade over time.
[0007] 3) Optical waveguide amplifiers based on glass and other materials. Glass has a low refractive index, a weak ability to confine light, and its own transmission loss is also large, making it difficult to achieve signal gain.
[0008] Therefore, finding a suitable semiconductor material as a matrix for erbium ion doping is a technical problem that needs to be solved urgently. Summary of the Invention
[0009] The object of the present invention is to provide a C-band oriented Er-doped AlN optical waveguide amplifier and a preparation method thereof, aiming to solve or improve at least one of the above-mentioned technical problems.
[0010] To achieve the above object, the present invention provides the following solutions:
[0011] A C-band oriented erbium-doped AlN optical waveguide amplifier comprises: a substrate layer, a buried oxide layer, an erbium-doped aluminum nitride waveguide layer, and a silicon dioxide cladding layer, which are arranged in sequence from bottom to top; wherein the erbium-doped aluminum nitride waveguide layer is a strip waveguide, and its crystal axis orientation is highly c-axis oriented.
[0012] Optionally, the substrate layer is made of thermal oxide or sapphire.
[0013] Optionally, the buried oxide layer is silicon dioxide, and has a thickness between 2 μm and 3 μm.
[0014] Optionally, the thickness of the erbium-doped aluminum nitride waveguide layer is 400 nm, and the erbium doping concentration ranges from 0% to 1.8%.
[0015] Optionally, the thickness of the silicon dioxide coating layer is 2 μm.
[0016] Optionally, a layer of erbium-doped aluminum oxide thin film is further provided between the erbium-doped aluminum nitride waveguide layer and the silicon dioxide cladding layer as a secondary active region of the erbium-doped aluminum nitride strip waveguide.
[0017] The present invention also provides a method for preparing a C-band erbium-doped AlN optical waveguide amplifier, which is used to prepare the erbium-doped AlN optical waveguide amplifier as described above, comprising:
[0018] Step 1: After cleaning and drying the thermal oxide sheet, a substrate layer and a buried oxide layer on the substrate layer are obtained;
[0019] Step 2: obtaining an erbium-doped aluminum nitride thin film layer on the buried oxide layer by erbium ion doping; wherein the erbium ion doping method includes magnetron sputtering and ion implantation;
[0020] Step 3: Processing the erbium-doped aluminum nitride thin film layer using photolithography and etching processes to obtain an aluminum nitride strip waveguide;
[0021] Step 4: depositing a silicon dioxide cladding layer on the erbium-doped aluminum nitride thin film layer by plasma enhanced chemical vapor deposition.
[0022] Optionally, when the erbium ion doping method is ion implantation, the preparation process is:
[0023] An aluminum nitride film layer is first obtained on the buried oxide layer by magnetron sputtering, and then erbium ions are implanted into the aluminum nitride film layer by ion implantation. The film is then annealed under nitrogen to eliminate lattice damage caused by the ion implantation and activate the erbium ions to obtain an erbium-doped aluminum nitride film.
[0024] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:
[0025] The present invention discloses a C-band erbium-doped AlN optical waveguide amplifier and its fabrication method. The amplifier comprises, arranged from bottom to top, a substrate layer, a buried oxide layer, an erbium-doped aluminum nitride waveguide layer, and a silicon dioxide cladding layer. The erbium-doped aluminum nitride waveguide layer is a strip waveguide with a highly c-axis oriented crystal axis. This invention addresses the low luminous efficiency caused by the temperature quenching effect of the erbium-doped semiconductor material used in current optical waveguide amplifiers, providing a feasible solution for realizing large-scale, integrated, high-gain optical waveguide amplifiers. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0027] Figure 1 Schematic diagram of the structure of the erbium-doped AlN optical waveguide amplifier in this embodiment;
[0028] Figure 2 Schematic diagram of a preparation method in this embodiment;
[0029] Figure 3 Schematic diagram of another preparation method in this embodiment. DETAILED DESCRIPTION
[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.
[0031] The object of the present invention is to provide a C-band oriented Er-doped AlN optical waveguide amplifier and a preparation method thereof, aiming to solve or improve at least one of the above-mentioned technical problems.
[0032] 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.
[0033] like Figure 1 To address the low luminous efficiency caused by the temperature quenching effect of erbium-doped semiconductor materials used in existing optical waveguide amplifiers, the present invention proposes a fabrication method for an erbium-doped aluminum nitride optical waveguide amplifier. The substrate for the erbium-doped aluminum nitride waveguide can be either thermal oxide (silicon dioxide on silicon) or sapphire.
[0034] The present invention provides a C-band erbium-doped AlN optical waveguide amplifier, comprising: a substrate layer, a buried oxide layer, an erbium-doped aluminum nitride waveguide layer, and a silicon dioxide cladding layer, which are arranged in sequence from bottom to top; wherein the erbium-doped aluminum nitride waveguide layer is a strip waveguide, and the crystal axis orientation is highly c-axis oriented.
[0035] This erbium-doped AlN optical waveguide amplifier first designs an erbium-doped aluminum nitride strip waveguide using a thermal oxide substrate. This creates a thermal oxide (or sapphire)-erbium-doped aluminum nitride waveguide-silicon dioxide cladding optical waveguide amplifier. Erbium ion doping can be achieved in two ways: first, by first forming an aluminum nitride film via magnetron sputtering, then implanting erbium ions into the aluminum nitride film via ion implantation; and second, by directly growing the erbium-doped aluminum nitride film via magnetron sputtering. This invention provides a feasible solution for realizing large-scale, integrated, high-gain optical waveguide amplifiers.
[0036] As a specific implementation, the specific parameters of the erbium-doped AlN optical waveguide amplifier include:
[0037] The thickness of the silicon is 625 μm, but is not limited to this size. The buried oxide layer is silicon dioxide, and has a thickness between 2 μm and 33 μm, but is not limited to this size.
[0038] The aluminum nitride waveguide has a thickness of 400 nm, but is not limited to this size. The aluminum nitride film has a high degree of c-axis orientation and an erbium doping concentration ranging from 0% to 1.8%. Its photoluminescence performance increases with increasing erbium doping concentration, and its refractive index in the near-infrared band is 2.04 to 2.13.
[0039] The cladding layer is 2 μm thick, but is not limited to this thickness. Silicon dioxide is commonly used as the cladding layer to reduce light loss at the waveguide-air interface and protect the waveguide. Alternatively, an erbium-doped aluminum oxide thin film can be added between the aluminum nitride and silicon dioxide cladding layers to serve as the secondary active region of the erbium-doped aluminum nitride strip waveguide, maximizing its signal gain.
[0040] In some embodiments, erbium ions can be co-doped with other rare earth elements (such as ytterbium and scandium) and oxygen into the aluminum nitride waveguide to enhance the erbium's luminescence performance. The aluminum nitride waveguide has a width of 0.8-0.9 μm, a bending radius greater than or equal to 100 μm, and a waveguide pitch of 10 μm, but is not limited to these dimensions. The thermal oxide substrate can be replaced with a sapphire substrate with a thickness of 500 μm, but is not limited to this dimension.
[0041] As another embodiment, a method for preparing the erbium-doped AlN optical waveguide amplifier is provided, wherein the erbium-doped aluminum nitride is a strip waveguide, specifically a silicon-silicon dioxide-erbium-doped aluminum nitride waveguide-silicon dioxide cladding optical waveguide amplifier.
[0042] like Figure 2 As shown, for the basic structure of a silicon-silicon dioxide-erbium-doped aluminum nitride waveguide-silicon dioxide cladding optical waveguide amplifier, the preparation method includes the following steps:
[0043] Step 1: After cleaning and drying the thermal oxide sheet, clean silicon (structure 1) and buried oxide layer (structure 2) are obtained.
[0044] Step 2: Obtain an erbium-doped aluminum nitride thin film layer on the buried oxide layer by magnetron sputtering (Structure 3).
[0045] Step 3: Obtain an aluminum nitride strip waveguide (structure 4) through photolithography and etching processes.
[0046] Step 4: depositing a silicon dioxide cladding layer on the erbium-doped aluminum nitride thin film layer by plasma enhanced chemical vapor deposition (Structure 5).
[0047] like Figure 3 As shown, the preparation method of erbium-doped aluminum nitride thin film by ion implantation includes the following steps:
[0048] Step 1: Clean the buried oxide layer (Structure 2).
[0049] Step 2: Obtain an aluminum nitride thin film layer (Structure 6) on the substrate material by magnetron sputtering.
[0050] Step 3: Inject erbium into the aluminum nitride film by ion implantation and perform annealing treatment under nitrogen to eliminate lattice damage caused by ion implantation and activate erbium ions to obtain an erbium-doped aluminum nitride film (Structure 7).
[0051] Therefore, this application has the following beneficial effects:
[0052] First, the present application reduces the thermal quenching effect of erbium and enhances the luminescence performance of erbium by doping erbium into aluminum nitride with a large bandgap, thereby improving the gain capability of the erbium-doped optical waveguide amplifier in the communication band.
[0053] Secondly, the present application provides two optional solutions for integration with different optical devices by growing aluminum nitride films on two different substrates, silicon dioxide and sapphire.
[0054] Finally, this application provides different solutions for process selection through different erbium ion doping methods. Direct preparation of erbium-doped aluminum nitride by magnetron sputtering makes the preparation process simpler; doping through ion implantation process can achieve co-doping of erbium and other elements, thereby achieving higher optical gain, providing a way of thinking for scenarios that require a smaller device area to achieve stability and high gain.
[0055] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.
[0056] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.
Claims
1. A C-band erbium-doped AlN optical waveguide amplifier, characterized in that: include: A substrate layer, a buried oxide layer, an erbium-doped aluminum nitride waveguide layer and a silicon dioxide cladding layer are sequentially arranged from bottom to top; wherein the erbium-doped aluminum nitride waveguide layer is a strip waveguide, and the crystal axis orientation is highly c-axis orientation.
2. The C-band erbium-doped AlN optical waveguide amplifier according to claim 1, characterized in that: The substrate layer is made of thermal oxide sheet or sapphire.
3. The C-band erbium-doped AlN optical waveguide amplifier according to claim 1, characterized in that: The buried oxide layer is silicon dioxide, and has a thickness between 2 μm and 3 μm.
4. The C-band erbium-doped AlN optical waveguide amplifier according to claim 1, characterized in that: The thickness of the erbium-doped aluminum nitride waveguide layer is 400 nm, and the erbium doping concentration ranges from 0% to 1.8%.
5. The C-band oriented Erbium-doped AlN optical waveguide amplifier according to claim 1, characterized in that: The thickness of the silicon dioxide coating layer is 2 μm.
6. The C-band oriented Erbium-doped AlN optical waveguide amplifier according to claim 1, characterized in that: A layer of erbium-doped aluminum oxide film is further arranged between the erbium-doped aluminum nitride waveguide layer and the silicon dioxide cladding layer as a secondary active region of the erbium-doped aluminum nitride strip waveguide.
7. A method for preparing a C-band erbium-doped AlN optical waveguide amplifier, for preparing the erbium-doped AlN optical waveguide amplifier according to any one of claims 1 to 6, characterized in that: include: Step 1: After cleaning and drying the thermal oxide sheet, a substrate layer and a buried oxide layer on the substrate layer are obtained; Step 2: obtaining an erbium-doped aluminum nitride thin film layer on the buried oxide layer by erbium ion doping; wherein the erbium ion doping method includes magnetron sputtering and ion implantation; Step 3: Processing the erbium-doped aluminum nitride thin film layer using photolithography and etching processes to obtain an aluminum nitride strip waveguide; Step 4: depositing a silicon dioxide cladding layer on the erbium-doped aluminum nitride thin film layer by plasma enhanced chemical vapor deposition.
8. The C-band oriented Erbium-doped AlN optical waveguide amplifier according to claim 7, characterized in that: When the erbium ion doping method adopts ion implantation, the preparation process is as follows: An aluminum nitride film layer is first obtained on the buried oxide layer by magnetron sputtering, and then erbium ions are implanted into the aluminum nitride film layer by ion implantation. The film is then annealed under nitrogen to eliminate lattice damage caused by the ion implantation and activate the erbium ions to obtain an erbium-doped aluminum nitride film.