Multilayer waveguide ring with quadrupole symmetrical structure

Abstract

The invention discloses a multilayer waveguide ring with a quadrupole symmetrical structure, which is characterized in that an interlayer coupler is adopted to expand a waveguide structure from two dimensions to three dimensions, the optical path of the waveguide ring is greatly lengthened by increasing the number of layers of optical waveguides under the condition of small size, and high precision of an integrated optical gyroscope is realized under the condition of small size; a quadrupole symmetrical structure is realized in the waveguide ring, and Shupe noise is effectively suppressed. The waveguide ring for the interference type integrated optical gyroscope solves the problems that after the ring length of an existing waveguide ring for the interference type integrated optical gyroscope is greatly increased through an interlayer coupler, the waveguide ring is easily influenced by Shupe noise caused by temperature gradient, and improvement of the gyroscope precision is limited.

Description

Technical Field

[0001] This invention belongs to the field of optical gyroscope design technology, and relates to a multilayer waveguide ring with a four-pole symmetric structure for integrated optical gyroscopes. Background Technology

[0002] In current research on interferometric integrated optical gyroscopes, the waveguide rings used are typically single-layer structures. Changes in the temperature gradient within the waveguide ring can lead to non-reciprocal noise between light propagating in clockwise and counterclockwise directions, thus affecting the detection accuracy of the interferometric integrated optical gyroscope. This noise is called Shupe noise, and its impact becomes increasingly pronounced with the increase in waveguide ring length and the improvement in the accuracy of the interferometric optical gyroscope. Therefore, after extending the waveguide ring structure longitudinally using interlayer couplers, it is crucial to focus on the interlayer arrangement of the optical waveguides within the waveguide ring to improve the gyroscope's detection accuracy. Summary of the Invention

[0003] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a multilayer waveguide ring with a four-pole symmetry structure. This solves the problem that the existing waveguide rings used in interferometric integrated optical gyroscopes are easily affected by Shupe noise caused by temperature gradients after the ring length is greatly increased through interlayer couplers, which limits the improvement of gyroscope accuracy.

[0004] The solution of the present invention is: A waveguide ring unit with a four-pole symmetry structure includes four single-layer waveguide rings, three interlayer couplers, and two input / output optical waveguides; the four single-layer waveguide rings are designated as the first single-layer waveguide ring, the second single-layer waveguide ring, the third single-layer waveguide ring, and the fourth single-layer waveguide ring; the three interlayer couplers are designated as the first interlayer coupler, the second interlayer coupler, and the third interlayer coupler; and the two input / output optical waveguides are designated as the first input / output optical waveguide and the second input / output optical waveguide. The second single-layer waveguide ring is connected to the third single-layer waveguide ring via the first interlayer coupler; the third single-layer waveguide ring is connected to the fourth single-layer waveguide ring via the second interlayer coupler; the fourth single-layer waveguide ring is connected to the first single-layer waveguide ring via the third interlayer coupler; the first single-layer waveguide ring is connected to the first input / output optical waveguide, and the second single-layer waveguide ring is connected to the second input / output optical waveguide.

[0005] Preferably, when the first input / output optical waveguide is a clockwise optical input port and a counterclockwise optical output port, the second input / output optical waveguide is a clockwise optical output port and a counterclockwise optical input port; When the second input / output optical waveguide is a clockwise optical input port and a counterclockwise optical output port, the first input / output optical waveguide is a clockwise optical output port and a counterclockwise optical input port.

[0006] Preferably, whether the light is input clockwise or counterclockwise, it will be in adjacent single-layer waveguide rings after the same transmission time, effectively reducing the impact of temperature gradient on gyroscope accuracy.

[0007] Preferably, the first single-layer waveguide ring, the second single-layer waveguide ring, the third single-layer waveguide ring, and the fourth single-layer waveguide ring are all multi-turn loop structures with the same number of turns.

[0008] A multilayer waveguide ring with a four-pole symmetric structure includes M groups of waveguide ring units; The m-th group of waveguide rings in the multilayer waveguide rings includes the 4m-3th single-layer waveguide ring, the 4m-2nd single-layer waveguide ring, the 4m-1st single-layer waveguide ring, and the 4mth single-layer waveguide ring; as well as two complete inter-layer couplers, the m-1st inter-layer coupler and the m-4th inter-layer coupler; and the m-2nd inter-layer coupler and the m-3rd inter-layer coupler formed together with the adjacent group of waveguide rings; The 4m single-layer waveguide ring is connected to the 4m-3 single-layer waveguide ring through the (m-1)th interlayer coupler; the 4m-1 single-layer waveguide ring is connected to the 4m-2 single-layer waveguide ring through the (m-4)th interlayer coupler. The m-th waveguide ring is adjacent to the k-th and n-th waveguide rings, respectively; the 4m-th single-layer waveguide ring is connected to the 4k-3-th single-layer waveguide ring through the (m-2)-th interlayer coupler, the 4m-1-th single-layer waveguide ring is connected to the 4k-2-th single-layer waveguide ring through the (m-3)-th interlayer coupler; the 4n-th single-layer waveguide ring is connected to the 4m-3-th single-layer waveguide ring through the (n-2)-th interlayer coupler; the 4n-1-th single-layer waveguide ring is connected to the 4m-2-th single-layer waveguide ring through the (n-3)-th interlayer coupler; m = 1, 2, 3, ..., M-1; Specifically, when m=1, i.e. in the first group of waveguide rings, the 0-3 and 0-2 interlayer couplers are replaced by input / output optical waveguides; when m=M, i.e. in the M group of waveguide rings, the M-2 and M-3 interlayer couplers form a complete interlayer coupler, connecting the clockwise and counterclockwise optical waveguides.

[0009] Preferably, under the same area, the M-group waveguide ring with a quadrupole symmetry structure increases the waveguide ring length by 4M times, and improves the theoretical limit accuracy of the gyroscope by 4M times.

[0010] Preferably, each group of waveguide rings has a multi-turn loop structure for its single-layer waveguide rings, and the number of turns of the single-layer waveguide rings in all groups is the same.

[0011] The advantages of this invention compared to the prior art are: (1) The present invention extends the waveguide structure from two-dimensional to three-dimensional by using interlayer couplers. By increasing the number of optical waveguide layers, the optical path of the waveguide ring is greatly extended in a small size, and the high precision of the integrated optical gyroscope is achieved in a small volume. (2) The present invention utilizes interlayer couplers to realize a quadrupole symmetric structure in the waveguide ring, which effectively suppresses Shupe noise. Attached Figure Description

[0012] Figure 1 This is a block diagram of a long-path waveguide ring optical path structure based on an interlayer coupler; Figure 2 This is a schematic diagram of a four-layer long-path waveguide ring unit based on an interlayer coupler. Figure 3 This is a schematic diagram of a cross-section of a long optical path 16-layer waveguide ring based on an interlayer coupler with a quadrupole symmetry structure. Figure 4 This is a schematic diagram of the cross-section of a long optical path 4M layer waveguide ring based on an interlayer coupler with a quadrupole symmetry structure. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0014] For interferometric integrated optical gyroscopes, since the gyroscope's limiting sensitivity is strongly correlated with the waveguide ring length, to achieve practical gyroscope accuracy (better than 0.5° / h), the waveguide ring length is typically no less than 100m. At this length, with a waveguide spacing of 50μm and a minimum bending radius of 10mm, the waveguide ring diameter is no less than 80mm. Clearly, this size is insufficient to meet the small-volume requirements of integrated optical gyroscopes. Therefore, to resolve the contradiction between size and accuracy, methods such as... Figure 1 The illustrated long-path waveguide ring design based on interlayer couplers extends the waveguide structure from two-dimensional to three-dimensional using interlayer couplers. This effectively leverages the fabrication advantages of integrated optics, significantly increasing the optical path length of the waveguide ring within a small size by increasing the number of waveguide layers, thus achieving high precision in a compact volume. The optical path structure comprises two input / output waveguides, multiple single-layer waveguide rings, and a corresponding number of interlayer couplers. The input / output waveguides are used to connect to other optical devices. Input / output waveguide 1 serves as a clockwise optical input and a counter-clockwise optical output port; input / output waveguide 2 serves as a clockwise optical output and a counter-clockwise optical input port. Clockwise light enters single-layer waveguide 1 through input / output waveguide 1, propagates a certain length within single-layer waveguide 1, and then enters the adjacent single-layer waveguide 1 through an interlayer coupler. After multiple cross-layer transmissions through interlayer coupler 1, it enters single-layer waveguide 2 and is output from input / output waveguide 2. The propagation path of counterclockwise light is completely reversed. After this optical path structure, the waveguide 1 length increases by N+2 times for the same area, and the theoretical limit accuracy of the gyroscope also increases by N+2 times accordingly.

[0015] Based on this, in order to suppress Shupe noise, a quadrupole symmetry structure is implemented in the waveguide ring using an interlayer coupler. Quadrupole symmetry is an effective means of suppressing Shupe noise and improving the reciprocity of interferometric fiber optic gyroscopes. The basic structure (waveguide ring unit) of the multilayer waveguide ring with quadrupole symmetry proposed in this invention is as follows: Figure 2 As shown, this scheme consists of four single-layer waveguide rings, three interlayer couplers, and two input / output optical waveguides. Single-layer waveguide ring 2 and 3 are connected via interlayer coupler 1; single-layer waveguide ring 3 and 4 are connected via interlayer coupler 2; and single-layer waveguide ring 4 and 1 are connected via interlayer coupler 3. Single-layer waveguide ring 1 is connected to input / output optical waveguide 1, and single-layer waveguide ring 2 is connected to input / output optical waveguide 2. This structure increases the waveguide ring length by four times within the same area, correspondingly improving the theoretical limit accuracy of the gyroscope by four times. In this case, whether the input light is clockwise or counterclockwise, it will be within adjacent single-layer waveguide rings after the same transmission time, effectively reducing the impact of temperature gradients on gyroscope accuracy.

[0016] Figure 4 An implementation scheme for a long optical path 4M waveguide ring with a four-pole symmetric structure based on interlayer couplers is presented. In this scheme, every four waveguide rings form a group, for a total of M groups. The m-th group contains four waveguide rings: 4m-3, 4m-2, 4m-1, and 4m. Each group contains two complete interlayer couplers, m-1 and m-4, which serve as connections between different waveguide rings within each group: the 4m-th layer is connected to the 4m-3-th layer via the m-1 interlayer coupler; the 4m-1-th layer is connected to the 4m-2-th layer via the m-4 interlayer coupler. In addition, the m-th group is connected to the adjacent k-th and n-th groups via interlayer couplers m-2, m-3, n-2, and n-3: the 4m-th layer is connected to the 4k-3-th layer via an m-2 interlayer coupler; the 4m-1-th layer is connected to the 4k-2-th layer via an m-3 interlayer coupler; the 4n-th layer is connected to the 4m-3-th layer via an n-2 interlayer coupler; and the 4n-1-th layer is connected to the 4m-2-th layer via an n-3 interlayer coupler. Specifically, when m=1 (for the first group), the 0-2 and 0-3 interlayer couplers are replaced by input / output optical waveguides; when m=M (for the M-th group), M-2 and M-3 form an interlayer coupler connecting the clockwise and counterclockwise optical waveguides.

[0017] Example: Figure 3 An implementation scheme for a long-path waveguide ring with a quadrupole symmetry structure based on an interlayer coupler is presented. Quadrupole symmetry is an effective means of suppressing Shupe noise and improving gyroscope reciprocity in interferometric fiber optic gyroscopes. By using an interlayer coupler, a quadrupole symmetry structure can also be realized in the waveguide ring. Figure 3In the specific implementation scheme given, M=3, that is, there are 12 waveguide layers. This number of layers can also be increased or decreased in multiples of 4 according to actual needs.

[0018] Counterclockwise light enters the waveguide ring through the input / output waveguide of the C1 layer structure, propagates K turns in this layer, and then enters the C4 layer structure via interlayer coupler 1-1; after propagating K turns in the C4 layer structure, it enters the C5 layer structure via interlayer coupler 1-2; after propagating K turns in the C5 layer structure, it enters the C8 layer structure via interlayer coupler 2-1; after propagating K turns in the C8 layer structure, it enters the C9 layer structure via interlayer coupler 2-2; after propagating K turns in the C9 layer structure, it enters the C12 layer structure via interlayer coupler 3-1; after propagating K turns in the C12 layer structure, it enters the C12 layer structure via interlayer coupler 3-2 and 3- The three interlayer couplers together enter the C11 layer structure; after transmitting K turns in the C11 layer structure, they enter the C10 layer structure via interlayer couplers 3-4; after transmitting K turns in the C10 layer structure, they enter the C7 layer structure via interlayer couplers 2-3; after transmitting K turns in the C7 layer structure, they enter the C6 layer structure via interlayer couplers 2-4; after transmitting K turns in the C6 layer structure, they enter the C3 layer structure via interlayer couplers 1-3; after transmitting K turns in the C3 layer structure, they enter the C2 layer structure via interlayer couplers 1-4; and after transmitting K turns in the C2 layer structure, they are output via the input / output optical waveguide.

[0019] Correspondingly, clockwise light enters the waveguide ring through the input / output waveguide of the C2 layer structure, and the transmission path is exactly the opposite of that of counterclockwise light.

[0020] This structure increases the waveguide ring length by 12 times within the same area, and correspondingly improves the theoretical limit accuracy of the gyroscope by 12 times. In this structure, whether the input light is clockwise or counterclockwise, it will be in adjacent single-layer waveguide rings after the same transmission time, thus effectively reducing the impact of temperature gradient on gyroscope accuracy.

[0021] The parts of this invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A waveguide ring unit with a four-pole symmetric structure, characterized in that: It includes four single-layer waveguide rings, three inter-layer couplers, and two input / output optical waveguides; the four single-layer waveguide rings are designated as the first single-layer waveguide ring, the second single-layer waveguide ring, the third single-layer waveguide ring, and the fourth single-layer waveguide ring; the three inter-layer couplers are designated as the first inter-layer coupler, the second inter-layer coupler, and the third inter-layer coupler; the two input / output optical waveguides are designated as the first input / output optical waveguide and the second input / output optical waveguide. The second single-layer waveguide ring is connected to the third single-layer waveguide ring via the first interlayer coupler; the third single-layer waveguide ring is connected to the fourth single-layer waveguide ring via the second interlayer coupler; the fourth single-layer waveguide ring is connected to the first single-layer waveguide ring via the third interlayer coupler; the first single-layer waveguide ring is connected to the first input / output optical waveguide, and the second single-layer waveguide ring is connected to the second input / output optical waveguide.

2. A waveguide ring unit with a four-pole symmetric structure according to claim 1, characterized in that: When the first input / output optical waveguide is a clockwise optical input and a counterclockwise optical output port, the second input / output optical waveguide is a clockwise optical output and a counterclockwise optical input port; When the second input / output optical waveguide is a clockwise optical input port and a counterclockwise optical output port, the first input / output optical waveguide is a clockwise optical output port and a counterclockwise optical input port.

3. A waveguide ring unit with a four-pole symmetric structure according to claim 1, characterized in that: Whether the light is input clockwise or counterclockwise, it will be in adjacent single-layer waveguide rings after the same transmission time, effectively reducing the impact of temperature gradient on gyroscope accuracy.

4. A waveguide ring unit with a four-pole symmetric structure according to claim 1, characterized in that: The first, second, third, and fourth single-layer waveguide rings are all multi-turn loop structures with the same number of turns.

5. A multilayer waveguide ring with a quadrupole symmetry structure, characterized in that: Includes the waveguide ring unit as described in claim 1 of group M; The m-th group of waveguide rings in the multilayer waveguide rings includes the 4m-3th single-layer waveguide ring, the 4m-2nd single-layer waveguide ring, the 4m-1st single-layer waveguide ring, and the 4mth single-layer waveguide ring; as well as two complete inter-layer couplers, the m-1st inter-layer coupler and the m-4th inter-layer coupler; and the m-2nd inter-layer coupler and the m-3rd inter-layer coupler formed together with the adjacent group of waveguide rings; The 4m single-layer waveguide ring is connected to the 4m-3 single-layer waveguide ring through the (m-1)th interlayer coupler; the 4m-1 single-layer waveguide ring is connected to the 4m-2 single-layer waveguide ring through the (m-4)th interlayer coupler. The m-th waveguide ring is adjacent to the k-th and n-th waveguide rings, respectively; the 4m-th single-layer waveguide ring is connected to the 4k-3-th single-layer waveguide ring through the (m-2)-th interlayer coupler, the 4m-1-th single-layer waveguide ring is connected to the 4k-2-th single-layer waveguide ring through the (m-3)-th interlayer coupler; the 4n-th single-layer waveguide ring is connected to the 4m-3-th single-layer waveguide ring through the (n-2)-th interlayer coupler; the 4n-1-th single-layer waveguide ring is connected to the 4m-2-th single-layer waveguide ring through the (n-3)-th interlayer coupler; m = 1, 2, 3, ..., M-1; Specifically, when m=1, i.e. in the first group of waveguide rings, the 0-3 and 0-2 interlayer couplers are replaced by input / output optical waveguides; when m=M, i.e. in the M group of waveguide rings, the M-2 and M-3 interlayer couplers form a complete interlayer coupler, connecting the clockwise and counterclockwise optical waveguides.

6. A multilayer waveguide ring with a quadrupole symmetry structure according to claim 5, characterized in that: Under the same area, the M-group waveguide ring with a quadrupole symmetry structure increases the waveguide ring length by 4M times, and improves the theoretical limit accuracy of the gyroscope by 4M times.

7. A multilayer waveguide ring with a quadrupole symmetry structure according to claim 5, characterized in that: Each waveguide ring in each group has a multi-turn loop structure, and the number of turns in the single-layer waveguide ring is the same in all groups.

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