Sensitive ring structure applied to interference type integrated optical gyroscope and preparation method of sensitive ring structure

Abstract

The invention provides a sensitive ring structure applied to an interference type integrated optical gyroscope and a preparation method of the sensitive ring structure. A first waveguide layer, a coupling layer and a second waveguide layer are sequentially formed on a substrate, a plurality of oxide layers are formed, and the first waveguide layer, the coupling layer and the second waveguide layer are all wrapped in the oxide layers; a first interlayer is arranged between the first waveguide layer and the coupling layer, a second interlayer is arranged between the coupling layer and the second waveguide layer, and finally the sensitive ring structure applied to the interference type integrated optical gyroscope is formed. When coupling transmission is carried out between the first waveguide layer and the second waveguide layer, no cross phenomenon exists between the output waveguide and the waveguide coil, so that crosstalk between the waveguides can be reduced, transmission loss between the waveguides can be reduced, and the distance between the first waveguide ring and the second waveguide ring is not too close due to the existence of the coupling layer. And inter-layer coupling crosstalk can be further reduced.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope technology, and in particular to a sensitive ring structure for use in interferometric integrated optical gyroscopes and its fabrication method. Background Technology

[0002] As an inertial sensor, a gyroscope can detect the angular velocity of a vehicle relative to inertial space without an external reference. Subsequent integration calculations yield the vehicle's attitude and trajectory. Based on their working principles, gyroscopes can be divided into two main categories: electromechanical gyroscopes based on classical mechanics and optical gyroscopes based on the Sagnac effect, which can be further divided into ring laser gyroscopes, fiber optic gyroscopes, and integrated optical gyroscopes. Among these, fiber optic gyroscopes (FOGs) have advantages such as high accuracy, good environmental adaptability, high long-term reliability, and insensitivity to acceleration, making them the mainstream sensor for navigation, guidance, and control. However, the relatively large size of fiber optic gyroscopes limits their application in systems such as drones and autonomous navigation. Especially with the continuous expansion of the application markets in robotics, automotive, and consumer electronics, gyroscopes are gradually developing towards miniaturization, low cost, and wearable designs.

[0003] Over the past half-century, with the development of photonic integrated circuits (PIC) and semiconductor manufacturing processes, two major branches of integrated optical gyroscope technology have emerged, corresponding to resonant optical gyroscopes and interferometric optical gyroscopes, respectively. Among them, integrated interferometric optical gyroscopes have significant advantages in integration and miniaturization, and possess strong resistance to mechanical vibration, high stability, small size, low power consumption, and portability, making them more suitable for large-scale, low-cost production to meet the application needs of the consumer market. To achieve higher sensitivity, integrated interferometric optical gyroscopes require lower transmission loss and roughness. Although the waveguide loss of the sensing ring in a single-layer Archimedean waveguide spiral structure can reach 0.78 dB / m, the winding of the sensing ring based on this structure suffers from crosstalk and other problems, and on-chip integration imposes certain limitations on the size of the sensing ring. When using a double-layer structure to avoid winding problems, the close interlayer spacing of the double-layer sensing rings easily leads to crosstalk and other issues.

[0004] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0005] The purpose of this invention is to provide a sensitive ring structure and its fabrication method for use in interferometric integrated optical gyroscopes, which solves the problems in the prior art where the output waveguide of the sensitive ring crosses with the waveguide coil and crosstalk is caused by the crossing or the layer spacing of the double-layer sensitive ring being too close.

[0006] To achieve the above and other related objectives, this invention provides a method for fabricating a sensitive ring structure for use in an interferometric integrated optical gyroscope, comprising the following steps:

[0007] A substrate is provided, and a first oxide layer is formed on the substrate;

[0008] A first waveguide layer is formed on the first oxide layer. The first waveguide layer includes at least a first annular waveguide structure. The two ends of the first annular waveguide structure are respectively coupled to a first coupler and a second coupler.

[0009] A first interlayer is formed on the first waveguide layer, and a coupling layer is formed on the first interlayer, wherein the coupling layer includes at least a third coupler and a fourth coupler;

[0010] A second interlayer is formed on the coupling layer, and a second waveguide layer is formed on the second interlayer. The second waveguide layer includes at least a second annular waveguide structure, and the two ends of the second annular waveguide structure are respectively connected to a fifth coupler and a sixth coupler.

[0011] A second oxide layer is formed on the second waveguide layer.

[0012] Optionally, the method for forming the first waveguide layer includes low-pressure chemical vapor deposition; the method for forming the coupling layer includes low-pressure chemical vapor deposition; the method for forming the second waveguide layer includes low-pressure chemical vapor deposition; and the method for forming the first interlayer, the second interlayer, and the second oxide layer includes chemical vapor deposition.

[0013] Optionally, the method for forming the first ring waveguide structure includes dry etching; the method for forming the second ring waveguide structure includes dry etching.

[0014] Optionally, the first waveguide layer, the coupling layer, and the second waveguide layer are made of silicon nitride; the first oxide layer, the second oxide layer, the first interlayer, and the second interlayer are made of silicon dioxide.

[0015] The present invention also provides a sensitive ring structure for use in an interferometric integrated optical gyroscope, the sensitive ring structure comprising:

[0016] A substrate, wherein a first oxide layer, a first waveguide layer, a first interlayer, a coupling layer, a second interlayer, a second waveguide layer, and a second oxide layer are disposed thereon from bottom to top;

[0017] The first waveguide layer includes at least a first ring waveguide structure, and the two ends of the first ring waveguide structure are coupled to a first coupler and a second coupler, respectively.

[0018] The coupling layer includes at least a third coupler and a fourth coupler;

[0019] The second waveguide layer includes at least a second annular waveguide structure, with its two ends connected to a fifth coupler and a sixth coupler, respectively. The first coupler, the third coupler, and the fifth coupler are distributed on the same vertical line, as are the second coupler, the fourth coupler, and the sixth coupler.

[0020] Optionally, the interlayer spacing between the first waveguide layer and the coupling layer is 0.5 to 2 μm, and the interlayer spacing between the coupling layer and the second waveguide layer is 0.5 to 2 μm.

[0021] Optionally, the cross-sectional width of the first annular waveguide structure is 3 to 10 μm, and the cross-sectional height of the first annular waveguide structure is 40 to 800 nm.

[0022] Optionally, the first ring waveguide structure and the second ring waveguide structure have the same cross-sectional dimensions.

[0023] Optionally, the first coupler, the second coupler, the third coupler, the fourth coupler, the fifth coupler, and the sixth coupler are all tapered couplers.

[0024] Optionally, the end face width of the tapered coupler is at least 0.8 μm and less than the width of the first annular waveguide structure, the height of the tapered coupler is the same as the height of the first annular waveguide structure, and the length of the tapered coupler is 300–800 μm.

[0025] As described above, the sensitive ring structure and its fabrication method for an interferometric integrated optical gyroscope of the present invention have the following beneficial effects: by forming a coupling layer between the first waveguide layer and the second waveguide layer, the waveguide crossing phenomenon between the first waveguide ring and the second waveguide ring is eliminated structurally, thereby reducing crosstalk caused by waveguide crossing. Furthermore, the presence of the coupling layer ensures that the distance between the first waveguide ring and the second waveguide ring is not too close, further reducing interlayer coupling crosstalk. In addition, using silicon nitride as the waveguide material can reduce transmission loss, thereby reducing the noise of the gyroscope. Attached Figure Description

[0026] Figure 1 The diagram shows a process flow diagram of the preparation method of the sensitive ring structure of the present invention.

[0027] Figure 2 The diagram shown is a structural schematic of the present invention after the formation of the first oxide layer.

[0028] Figure 3 The diagram shown is a schematic representation of the structure after the formation of the first waveguide layer according to the present invention.

[0029] Figure 4 The diagram shown is a schematic representation of the structure after the coupling layer is formed according to the present invention.

[0030] Figure 5 The diagram shown is a schematic representation of the structure after the formation of the second waveguide layer according to the present invention.

[0031] Figure 6 The diagram shown is a cross-sectional view of the sensitive ring structure of the present invention.

[0032] Figure 7 The diagram shown is a three-dimensional structural schematic of the sensitive ring structure of the present invention.

[0033] Component designation explanation

[0034] 101. Substrate; 102. First oxide layer; 103. First waveguide layer; 1031. First coupler; 1032. Second coupler; 1033. First ring waveguide structure; 104. First interlayer; 105. Coupler layer; 1051. Third coupler; 1052. Fourth coupler; 106. Second interlayer; 107. Second waveguide layer; 1071. Fifth coupler; 1073. Second ring waveguide structure; 1072. Sixth coupler; 108. Second oxide layer; S1-S5. Steps. Detailed Implementation

[0035] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0036] Please see Figures 1 to 7 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0037] Example 1

[0038] This invention provides a method for fabricating a sensitive ring structure for use in interferometric integrated optical gyroscopes, such as... Figure 1 The diagram shows a process flow diagram for fabricating the sensitive ring structure used in an interferometric integrated optical gyroscope, including the following steps:

[0039] S1: A substrate 101 is provided, and a first oxide layer 102 is formed on the substrate 101;

[0040] S2: A first waveguide layer 103 is formed on the first oxide layer 102. The first waveguide layer 103 includes at least a first annular waveguide structure 1033. The two ends of the first annular waveguide structure 1033 are coupled to a first coupler 1031 and a second coupler 1032, respectively.

[0041] S3: A first interlayer 104 is formed on the first waveguide layer 103, and a coupling layer 105 is formed on the first interlayer 104. The coupling layer 105 includes at least a third coupler 1051 and a fourth coupler 1052.

[0042] S4: A second interlayer 106 is formed on the coupling layer 105, and a second waveguide layer 107 is formed on the second interlayer 106. The second waveguide layer 107 includes at least a second annular waveguide structure 1073. The two ends of the second annular waveguide structure 1073 are respectively connected to the fifth coupler 1071 and the sixth coupler 1072.

[0043] S5: A second oxide layer 108 is formed on the second waveguide layer 107.

[0044] The following describes in detail, with reference to the accompanying drawings, the fabrication method of the sensitive ring structure applied to the interferometric integrated optical gyroscope in this embodiment.

[0045] In step S1, please refer to Figure 1 and Figure 2 A substrate 101 is provided, and a first oxide layer 102 is formed on the substrate 101.

[0046] As an example, substrate 101 has a front side and a back side disposed opposite to each other. The material of substrate 101 can be silicon-based, and its shape can be circular, square, or any other desired shape. In addition, the material of substrate 101 may also include other elemental semiconductors (such as germanium), or other compound semiconductors (such as silicon carbide, gallium arsenide, indium arsenide, indium phosphide, etc.), which are not particularly limited here.

[0047] Specifically, such as Figure 2As shown, a first oxide layer 102 is formed on the front side of the substrate 101. Optionally, the first oxide layer 102 can be a silicon oxide layer obtained by thermal oxidation growth. Compared with a silicon oxide layer deposited by chemical vapor deposition (CVD), the first oxide layer 102 obtained by thermal oxidation growth has a higher density and is less susceptible to corrosion. In addition, after forming the first oxide layer 102, a planarization process is performed on the first oxide layer 102 to improve the quality of the subsequent deposition to form the first waveguide layer 103.

[0048] In step S2, please refer to Figure 1 , Figure 3 and Figure 7 A first waveguide layer 103 is formed on the first oxide layer 102. The first waveguide layer 103 includes at least a first annular waveguide structure 1033. The two ends of the first annular waveguide structure 1033 are coupled to a first coupler 1031 and a second coupler 1032, respectively.

[0049] As an example, methods for forming the first waveguide layer 103 include low-pressure chemical vapor deposition or other suitable methods.

[0050] Specifically, by selecting appropriate gas components and a suitable temperature, a first waveguide layer 103 of a certain thickness is formed using low-pressure chemical vapor deposition (CVD) of silicon nitride. Then, the first waveguide layer 103 is patterned and etched to obtain a first annular waveguide structure 1033. Next, an oxide layer is deposited on the first oxide layer 102 using CVD again to encapsulate the first annular waveguide structure 1033, the first coupler 1031, and the second coupler 1032. Simultaneously, the etching process is controlled to form the first coupler 1031 and the second coupler 1032 at both ends of the first annular waveguide structure 1033, respectively. The first coupler 1031 is connected to the first annular waveguide structure 1033, and the second coupler 1032 is coupled to the first annular waveguide structure 1033 in a non-contact manner. In this embodiment, the thickness of the first waveguide layer 103 is 40–800 nm, and the first waveguide layer can be a Si3N4 layer. Both the first coupler 1031 and the second coupler 1032 are tapered couplers.

[0051] In step S3, please refer to Figure 1 , Figure 4 and Figure 7 A first interlayer 104 is formed on the first waveguide layer 103, and a coupling layer 105 is formed on the first interlayer 104. The coupling layer 105 includes at least a third coupler 1051 and a fourth coupler 1052.

[0052] As an example, methods for forming the coupling layer 105 include low-pressure chemical vapor deposition or other suitable methods.

[0053] Specifically, before forming the coupling layer 105, an oxide layer 104 is deposited on the first waveguide layer 103 using a chemical vapor deposition process. Furthermore, after forming the first interlayer 104, a planarization process is performed on it to improve the quality of the subsequently deposited coupling layer 105. In this embodiment, since the first interlayer 104 is also made of silicon dioxide, its bonding with the oxide-coated first waveguide layer 103 improves the reliability of the formed sensitive ring structure. Moreover, the process for forming the coupling layer 105 is the same as that for forming the first waveguide layer 103, and will not be described again here. In this embodiment, the coupling layer 105 includes at least a third coupler 1051 and a fourth coupler 1052. The fourth coupler 1052 includes two series-connected tapered couplers, one of which is coupled to the first waveguide layer 103 and the other is coupled to the second waveguide layer 107. That is, the second coupler 1032 and the fourth coupler 1052 are coupled to realize the transmission of light waves in the vertical direction, that is, from the first waveguide layer 103 to the coupling layer 105. The third coupler 1051 and the first coupler 1031 are coupled to realize the transmission of light waves in the vertical direction, that is, from the coupling layer 105 to the first waveguide layer 103. The third coupler 1051 and the fourth coupler 1052 are both tapered couplers, and the first coupler 1031 and the third coupler 1051 are distributed on the same vertical line. The second coupler 1032 and the fourth coupler 1052 are also distributed on the same vertical line. In this embodiment, the thickness of the coupling layer 105 is 40-800 nm, and the coupling layer can be a SiN layer.

[0054] In step S4, please refer to Figure 1 , Figure 5 and Figure 7 A second interlayer 106 is formed on the coupling layer 105, and a second waveguide layer 107 is formed on the second interlayer 106. The second waveguide layer 107 includes at least a second annular waveguide structure 1073, and the two ends of the second annular waveguide structure 1073 are respectively connected to a fifth coupler 1071 and a sixth coupler 1072.

[0055] As an example, methods for forming the second waveguide layer 107 include low-pressure chemical vapor deposition or other suitable methods.

[0056] Specifically, oxide is first deposited on the first interlayer 104 using chemical vapor deposition (CVD) to coat the third coupler 1051 and the fourth coupler 1052. Before forming the second waveguide layer 107, oxide is deposited on the coupling layer 105 using CVD to form the second interlayer 106, and the second interlayer 106 is planarized to improve the quality of the subsequently deposited second waveguide layer 107. Furthermore, the process for forming the second waveguide layer 107 is the same as that for forming the first waveguide layer 103, and will not be described in detail here. In this embodiment, the second waveguide layer 107 includes a second annular waveguide structure 1073. A fifth coupler 1071 and a sixth coupler 1072 are respectively connected to both ends of the second waveguide ring. Both the fifth coupler 1071 and the sixth coupler 1072 are tapered couplers, and the fifth coupler 1071 and the third coupler 1051 are distributed on the same vertical line, as are the sixth coupler 1072 and the fourth coupler 1052. In this embodiment, the thickness of the second waveguide layer 107 is 40–800 nm, and the second waveguide layer can be a Si3N4 layer.

[0057] In step S5, please refer to Figure 1 and Figure 6 A second oxide layer 108 is formed on the second waveguide layer 107.

[0058] As an example, methods for forming the second oxide layer 108 include chemical vapor deposition or other suitable methods.

[0059] Specifically, before depositing silicon dioxide on the second waveguide layer 107 to form the second oxide layer 108 using chemical vapor deposition, oxide is first deposited on the second interlayer 106 using chemical vapor deposition to cover the second annular waveguide structure 1073, the fifth coupler 1071, and the sixth coupler 1072. After forming the second oxide layer 108, a planarization process is performed on the second oxide layer 108 to obtain a flat surface. In addition, after forming the second oxide layer 108, a long-term high-temperature annealing process is required on the formed sensitive ring structure to minimize the absorption loss of the waveguide.

[0060] The method for fabricating the sensitive ring structure of the interferometric integrated optical gyroscope in this embodiment combines a low-pressure chemical vapor deposition (LPD) process to sequentially form a first waveguide layer 103, a coupling layer 105, and a second waveguide layer 107 on a substrate 101. Combining the LPD and CMP processes, multiple oxide layers are formed on the substrate 101, and the first waveguide layer 103, coupling layer 105, and second waveguide layer 107 are all encapsulated within the oxide layers. A first interlayer 104 is provided between the first waveguide layer 103 and the coupling layer 105, and a second interlayer 106 is provided between the coupling layer 105 and the second waveguide layer 107. With the sensitive ring structure formed by the above process, when the first waveguide layer 103 and the second waveguide layer 107 are coupled and transmitted, there is no crossover phenomenon between the output waveguide and the waveguide coil, thereby reducing crosstalk between waveguides and reducing transmission loss between waveguides. Furthermore, the presence of the coupling layer 105 ensures that the distance between the first waveguide ring and the second waveguide ring is not too close, which further reduces the coupling crosstalk between layers.

[0061] Example 2

[0062] This embodiment provides a sensitive ring structure for use in an interferometric integrated optical gyroscope. The sensitive ring structure includes: a substrate 101, on which a first oxide layer 102, a first waveguide layer 103, a first interlayer 104, a coupling layer 105, a second interlayer 106, a second waveguide layer 107, and a second oxide layer 108 are sequentially disposed from bottom to top.

[0063] The first waveguide layer 103 includes at least a first ring waveguide structure 1033, and the two ends of the first ring waveguide structure 1033 are coupled to a first coupler 1031 and a second coupler 1032, respectively.

[0064] The coupling layer 105 includes at least a third coupler 1051 and a fourth coupler 1052;

[0065] The second waveguide layer 107 includes at least a second annular waveguide structure 1073. The two ends of the second annular waveguide structure 1073 are respectively connected to a fifth coupler 1071 and a sixth coupler 1072. The first coupler 1031, the third coupler 1051 and the fifth coupler 1071 are distributed on the same vertical line, and the second coupler 1032, the fourth coupler 1052 and the sixth coupler 1072 are distributed on the same vertical line.

[0066] Specifically, the material of substrate 101 can be silicon-based material. In addition, the material of substrate 101 can also include other elemental semiconductors (such as germanium) or other compound semiconductors (such as silicon carbide, gallium arsenide, indium arsenide, indium phosphide, etc.). Since the material of substrate 101 does not affect the realization of the technical solution, this application does not limit the material of substrate 101.

[0067] As an example, the interlayer spacing between the first waveguide layer 103 and the coupling layer 105 is 0.5 to 2 μm, and the interlayer spacing between the coupling layer 105 and the second waveguide layer 107 is 0.5 to 2 μm.

[0068] Specifically, in this embodiment, the materials of the first oxide layer 102, the second oxide layer 108, the third oxide layer, and the fourth oxide layer are all selected as silicon dioxide. At the same time, in order to prevent the interlayer spacing between the first waveguide layer 103 and the second waveguide layer 107 from being too close, the interlayer spacing between the first waveguide layer 103 and the coupling layer 105 is 0.5 to 2 μm. For example, the interlayer spacing between the first waveguide layer 103 and the coupling layer 105 is 0.5 μm, 1 μm, 1.5 μm, or 2 μm. The interlayer spacing between the coupling layer 105 and the second waveguide layer 107 is 0.5 to 2 μm. For example, the interlayer spacing between the coupling layer 105 and the second waveguide layer 107 is 0.5 μm, 1 μm, 1.5 μm, or 2 μm. Through the above settings, the crosstalk phenomenon between waveguide layers can be reduced.

[0069] As an example, the cross-sectional width of the first ring waveguide structure 1033 is 3 to 10 μm, and the cross-sectional height of the first ring waveguide structure 1033 is 40 to 800 nm.

[0070] Specifically, in this embodiment, in order to ensure that the waveguide size meets the requirements of the sensitive ring structure, the cross-sectional width of the first ring waveguide structure 1033 is 3 to 10 μm, for example, the cross-sectional width is 3 μm, 7 μm or 10 μm, and the cross-sectional height of the first ring waveguide structure 1033 is 40 to 800 nm, for example, the cross-sectional height is 40 nm, 400 nm or 800 nm.

[0071] As an example, the first ring waveguide structure 1033 and the second ring waveguide structure 1073 have the same dimensions.

[0072] Specifically, in this embodiment, in order to achieve better coupling effect, the dimensions of the second ring waveguide structure 1073 are set to be the same as those of the first ring waveguide structure 1033. That is, the cross-sectional width of the second ring waveguide structure 1073 is 3 to 10 μm, the cross-sectional height of the second ring waveguide structure 1073 is 40 to 800 nm, and the second ring waveguide structure 1073 and the first ring waveguide structure 1033 have the same bending radius and ring spacing.

[0073] As an example, the first coupler 1031, the second coupler 1032, the third coupler 1051, the fourth coupler 1052, the fifth coupler 1071, and the sixth coupler 1072 are all tapered couplers.

[0074] As an example, the width of the tapered coupler is at least 0.8 μm and is smaller than the width of the first annular waveguide structure 1033, the height of the tapered coupler is the same as the height of the first annular waveguide structure 1033, and the length of the tapered coupler is 300 to 800 μm.

[0075] Specifically, such as Figure 7 As shown, in this embodiment, since the first coupler 1031 is connected to the first ring waveguide structure 1033, the height of the first coupler 1031 is the same as the height of the first ring waveguide structure 1033. The width of the narrow end of the first coupler 1031 is at least 0.8 μm, and the width of the end connected to the first ring waveguide structure 1033 is smaller than the width of the first ring waveguide structure 1033. The length of the first coupler 1031 is set to 300-800 μm. When the light wave is transmitted from the first ring waveguide structure 1033 to the first coupler 1031, since both the first coupler 1031 and the third coupler 1051 are tapered waveguides, as the geometric size of the first coupler 1031 decreases, the waveguide's ability to confine the light wave gradually decreases, thereby causing the optical mode field to gradually extend towards the waveguide of the coupling layer 105, ultimately realizing the transmission of the light wave in the vertical direction.

[0076] Depend on Figure 7 It can be seen that the first coupler 1031, the third coupler 1051, and the fifth coupler 1071 are distributed on the same vertical line. Since they are all tapered couplers, when the light wave is transmitted through the first ring waveguide structure 1033 to the first coupler 1031, as the geometric size of the first coupler 1031 decreases, the waveguide's ability to confine the light wave gradually decreases. This causes the optical mode field to gradually extend towards the waveguide of the coupling layer 105, ultimately realizing the transmission of the light wave in the vertical direction, that is, the light wave travels from the first coupler 1031 through the third... Coupler 1051 transmits to the fifth coupler 1071. Similarly, the second coupler 1032, the fourth coupler 1052, and the sixth coupler 1072 are distributed on the same vertical line. The light wave is transmitted to the fifth coupler 1071 in the second ring waveguide structure 1073. The light wave is transmitted vertically again using a tapered coupler. The light wave is transmitted from the sixth coupler 1072 to the second coupler 1032 via the fourth coupler 1052, and then transmitted out through one end of the first ring waveguide structure 1033.

[0077] In summary, the sensitive ring structure and its fabrication method for an interferometric integrated optical gyroscope of the present invention involve sequentially forming a first waveguide layer, a coupling layer, and a second waveguide layer on a substrate, and forming multiple oxide layers, with the first waveguide layer, coupling layer, and second waveguide layer all encapsulated within the oxide layers. A first interlayer is disposed between the first waveguide layer and the coupling layer, and a second interlayer is disposed between the coupling layer and the second waveguide layer, ultimately forming the sensitive ring structure for an interferometric integrated optical gyroscope. When the first waveguide layer and the second waveguide layer are coupled and transmitted, there is no crossover phenomenon between the output waveguide and the waveguide coil, thereby reducing inter-waveguide crosstalk and transmission loss. Furthermore, the presence of the coupling layer ensures that the distance between the first waveguide ring and the second waveguide ring is not too close, further reducing inter-layer coupling crosstalk. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0078] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for fabricating a sensitive ring structure for use in an interferometric integrated optical gyroscope, characterized in that, The steps include: A substrate is provided, and a first oxide layer is formed on the substrate; A first waveguide layer is formed on the first oxide layer. The first waveguide layer includes at least a first annular waveguide structure. The two ends of the first annular waveguide structure are respectively coupled to a first coupler and a second coupler. A first interlayer is formed on the first waveguide layer, and a coupling layer is formed on the first interlayer, wherein the coupling layer includes at least a third coupler and a fourth coupler; A second interlayer is formed on the coupling layer, and a second waveguide layer is formed on the second interlayer. The second waveguide layer includes at least a second annular waveguide structure, and the two ends of the second annular waveguide structure are respectively connected to a fifth coupler and a sixth coupler. A second oxide layer is formed on the second waveguide layer.

2. The method for preparing the sensitive ring structure according to claim 1, characterized in that: The method for forming the first waveguide layer includes low-pressure chemical vapor deposition; the method for forming the coupling layer includes low-pressure chemical vapor deposition; the method for forming the second waveguide layer includes low-pressure chemical vapor deposition; and the method for forming the first interlayer, the second interlayer, and the second oxide layer includes chemical vapor deposition.

3. The method for fabricating the sensitive ring structure according to claim 1, characterized in that: The method for forming the first ring waveguide structure includes dry etching; the method for forming the second ring waveguide structure includes dry etching.

4. The method for fabricating the sensitive ring structure according to claim 3, characterized in that: The first waveguide layer, the coupling layer, and the second waveguide layer are made of silicon nitride; the first oxide layer, the second oxide layer, the first interlayer, and the second interlayer are made of silicon dioxide.

5. A sensitive ring structure for use in an interferometric integrated optical gyroscope, characterized in that, The sensitive ring structure includes: A substrate, wherein a first oxide layer, a first waveguide layer, a first interlayer, a coupling layer, a second interlayer, a second waveguide layer, and a second oxide layer are disposed thereon from bottom to top; The first waveguide layer includes at least a first ring waveguide structure, and the two ends of the first ring waveguide structure are coupled to a first coupler and a second coupler, respectively. The coupling layer includes at least a third coupler and a fourth coupler; The second waveguide layer includes at least a second annular waveguide structure, with its two ends connected to a fifth coupler and a sixth coupler, respectively. The first coupler, the third coupler, and the fifth coupler are distributed on the same vertical line, as are the second coupler, the fourth coupler, and the sixth coupler.

6. The sensitive ring structure according to claim 5, characterized in that: The interlayer spacing between the first waveguide layer and the coupling layer is 0.5 to 2 μm, and the interlayer spacing between the coupling layer and the second waveguide layer is 0.5 to 2 μm.

7. The sensitive ring structure according to claim 5, characterized in that: The cross-sectional width of the first ring waveguide structure is 3 to 10 μm, and the cross-sectional height of the first ring waveguide structure is 40 to 800 nm.

8. The sensitive ring structure according to claim 7, characterized in that: The first ring waveguide structure and the second ring waveguide structure have the same cross-sectional dimensions.

9. The sensitive ring structure according to claim 5, characterized in that: The first coupler, the second coupler, the third coupler, the fourth coupler, the fifth coupler, and the sixth coupler are all tapered couplers.

10. The sensitive ring structure according to claim 9, characterized in that: The end face width of the tapered coupler is at least 0.8 μm and is smaller than the width of the first annular waveguide structure. The height of the tapered coupler is the same as the height of the first annular waveguide structure. The length of the tapered coupler is 300–800 μm.

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