Silicon photon gyroscope with film-coated mode filtering double-Y waveguide integrated structure
By employing a coated mode filter dual Y-waveguide integrated structure in a silicon photonic gyroscope, and utilizing symmetry optimization design and coated filter to suppress higher-order modes, the zero-position drift problem caused by the dual Y-waveguide structure is solved, significantly improving zero-bias stability and measurement accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-03-13
AI Technical Summary
Mode leakage in the dual Y-waveguide structure of traditional silicon photonic gyroscopes leads to zero-point drift, affecting the zero-bias stability and accuracy of the gyroscope. In particular, in high-precision inertial sensors, the zero-point drift can reach the order of 0.01°/h.
A coated mode filter dual Y-waveguide integrated structure is adopted. The bifurcation angle of the Y-waveguide is controlled between 8 and 12° through symmetry optimization design. Combined with the coated spatial mode filter, higher-order modes are suppressed, and new modes introduced by temperature gradient and stress are prevented, so as to achieve selective suppression of higher-order spatial modes.
It significantly reduces spatial radiation mode error and null drift, improves the zero-bias stability and measurement accuracy of silicon photonic gyroscopes, and achieves a null drift improvement factor of 138 times, meeting the requirements of high-precision inertial measurement.
Smart Images
Figure CN121655486A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of micro-nano photonic integration technology, and in particular to a silicon photonic gyroscope with a coated mode-filtered dual Y-waveguide integrated structure. Background Technology
[0002] As inertial navigation systems evolve towards miniaturization, low power consumption, and high reliability, traditional mechanical and fiber optic gyroscopes, due to their large size, high cost, and difficulty in integration, can no longer meet the needs of next-generation unmanned aerial vehicles, autonomous vehicles, and microsatellites. Silicon photonic gyroscopes, with their advantages of compatibility with CMOS processes, small size, and mass production capabilities, have become an important technological path for next-generation high-precision inertial sensors.
[0003] In silicon photonic gyroscopes, the dual Y-waveguide structure is the core component for beam splitting and combining optical signals. Ideally, the system should operate in a single fundamental mode (TE0) to ensure the stability and repeatability of the interference signal. Although Y-waveguides are widely used in single-function devices (such as modulators), integrating both Y-waveguides onto a bulk material (such as silicon) in silicon photonic gyroscopes can lead to severe Spatial Radiation Mode Error (SRME), introducing additional DC bias phase, manifested as bias drift, which significantly affects the gyroscope's zero-bias stability. Existing research shows that when the proportion of TE1 mode exceeds 5%, the bias drift can reach the order of 0.01° / h, limiting the practical application of the device. Therefore, there is an urgent need for a dual Y-waveguide integrated structure optimized specifically for silicon photonic gyroscopes that can effectively suppress mode leakage and significantly reduce bias error. Summary of the Invention
[0004] This invention provides a silicon photonic gyroscope with a coated mode-filtered dual Y-waveguide integrated structure, which can solve the technical problem of zero-position drift caused by mode leakage in the dual Y-waveguide in the prior art.
[0005] This invention provides a silicon photonic gyroscope with a coated mode-filtered dual Y-waveguide integrated structure, comprising a laser, a detector, a symmetrical dual Y-waveguide, a first filter, a second filter, a third filter, a fourth filter, a first phase modulator, a second phase modulator, and a ring.
[0006] The laser is used to emit laser light;
[0007] The first port of the symmetrical double Y waveguide is used to receive laser light, and the first optical signal is emitted from the third port and the second optical signal is emitted from the fourth port; the third port of the symmetrical double Y waveguide is used to receive the counterclockwise optical signal after secondary filtering, the fourth port is used to receive the clockwise optical signal after secondary filtering, and the interference-enhanced optical signal is emitted from the second port.
[0008] The first filter is used to receive a first optical signal, filter the first optical signal to obtain a filtered first optical signal; it is also used to receive a modulated counterclockwise optical signal, filter the modulated counterclockwise optical signal to obtain a second-filtered counterclockwise optical signal.
[0009] The second filter is used to receive the second optical signal, filter the second optical signal to obtain the filtered second optical signal; it is also used to receive the modulated clockwise optical signal, filter the modulated clockwise optical signal to obtain the second filtered clockwise optical signal.
[0010] The first phase modulator is used to receive the filtered first optical signal, perform phase modulation on the filtered first optical signal to obtain the modulated first optical signal; it is also used to receive the filtered counterclockwise optical signal, perform phase modulation on the filtered counterclockwise optical signal to obtain the modulated counterclockwise optical signal.
[0011] The second phase modulator is used to receive the filtered second optical signal, perform phase modulation on the filtered second optical signal to obtain the modulated second optical signal; it is also used to receive the filtered clockwise optical signal, perform phase modulation on the filtered clockwise optical signal to obtain the modulated clockwise optical signal.
[0012] The third filter is used to receive the modulated first optical signal, filter the modulated first optical signal to obtain the second filtered first optical signal; it is also used to receive the counterclockwise optical signal, filter the counterclockwise optical signal to obtain the filtered counterclockwise optical signal.
[0013] The fourth filter is used to receive the modulated second optical signal, filter the modulated second optical signal to obtain the second optical signal after secondary filtering; it is also used to receive the clockwise optical signal, filter the clockwise optical signal to obtain the filtered clockwise optical signal.
[0014] The ring is used to receive the first optical signal and the second optical signal after secondary filtering. The first optical signal and the second optical signal after secondary filtering rotate clockwise and counterclockwise respectively. After rotating several times, the clockwise optical signal and the counterclockwise optical signal are emitted from the ring.
[0015] The detector is used to receive the interfering optical signal and perform photoelectric conversion on the interfering optical signal to obtain the phase difference electrical signal.
[0016] Among them, the first filter, the second filter, the third filter, and the fourth filter are all coated spatial mode filters.
[0017] Preferably, each coated spatial mode filter consists of a lower cladding layer, a lower thin film, a spacer layer, an upper thin film, and an upper cladding layer from bottom to top; the lower cladding layer, the spacer layer, and the upper cladding layer are all made of SiO2 material, and the lower thin film and the upper thin film are both made of Si3N4 material.
[0018] Preferably, the thickness of the lower cladding layer is 2000 nm, the thickness of the lower thin film is 180 nm, the thickness of the spacer layer is 90 nm, the thickness of the upper thin film is 180 nm, and the thickness of the upper cladding layer is greater than or equal to 1500 nm.
[0019] Preferably, the bifurcation angle range of the first and second ports of the symmetrical double Y waveguide is 8 to 12°, and the bifurcation angle range of the third and fourth ports is 8 to 12°.
[0020] Applying the technical solution of this invention, the symmetrical dual Y-waveguide employs a symmetrical optimization design. This is achieved by collaboratively optimizing the two Y-waveguides to reduce mode excitation. The bifurcation angle between the front and rear Y-waveguides is controlled at 8–12°, keeping the higher-order mode excitation rate below 1%, thereby significantly reducing spatial radiation mode error (SRME) and null drift. Higher-order modes excited during beam splitting are suppressed by the first and second filters, while new modes introduced by temperature gradients or stress are prevented by the third and fourth filters. Selective suppression of higher-order spatial modes is achieved through a coated filter structure, while maintaining low-loss transmission of the fundamental mode, thus significantly improving the zero-bias stability and measurement accuracy of the silicon photonic gyroscope. This invention is applicable to high-precision inertial measurement scenarios such as SOI (Silicon-on-Insulator) platforms, aerospace, unmanned systems, and intelligent navigation. Attached Figure Description
[0021] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.
[0022] Figure 1 A schematic diagram of a silicon photonic gyroscope with a coated mode-filtered dual Y-waveguide integrated structure according to an embodiment of the present invention is shown.
[0023] Figure 2 A general process flow diagram of a silicon photonic gyroscope filter according to an embodiment of the present invention is shown. Detailed Implementation
[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0026] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.
[0027] like Figure 1 As shown, the present invention provides a silicon photonic gyroscope with a coated mode-filtered dual Y-waveguide integrated structure, including a laser, a detector, a symmetrical dual Y-waveguide, a first filter, a second filter, a third filter, a fourth filter, a first phase modulator, a second phase modulator, and a ring.
[0028] The laser is used to emit laser light;
[0029] The first port of the symmetrical double Y-waveguide is used to receive laser light, and the third port emits a first optical signal, while the fourth port emits a second optical signal. The third port of the symmetrical double Y-waveguide is used to receive a counterclockwise optical signal after secondary filtering, and the fourth port is used to receive a clockwise optical signal after secondary filtering. The second port emits an interferometric optical signal. The bifurcation angle between the first and second ports of the symmetrical double Y-waveguide is 8–12°, and the bifurcation angle between the third and fourth ports is 8–12°.
[0030] The first filter is used to receive a first optical signal, filter the first optical signal to obtain a filtered first optical signal; it is also used to receive a modulated counterclockwise optical signal, filter the modulated counterclockwise optical signal to obtain a second-filtered counterclockwise optical signal.
[0031] The second filter is used to receive the second optical signal, filter the second optical signal to obtain the filtered second optical signal; it is also used to receive the modulated clockwise optical signal, filter the modulated clockwise optical signal to obtain the second filtered clockwise optical signal.
[0032] The first phase modulator is used to receive the filtered first optical signal, perform phase modulation on the filtered first optical signal to obtain the modulated first optical signal; it is also used to receive the filtered counterclockwise optical signal, perform phase modulation on the filtered counterclockwise optical signal to obtain the modulated counterclockwise optical signal.
[0033] The second phase modulator is used to receive the filtered second optical signal, perform phase modulation on the filtered second optical signal to obtain the modulated second optical signal; it is also used to receive the filtered clockwise optical signal, perform phase modulation on the filtered clockwise optical signal to obtain the modulated clockwise optical signal.
[0034] The third filter is used to receive the modulated first optical signal, filter the modulated first optical signal to obtain the second filtered first optical signal; it is also used to receive the counterclockwise optical signal, filter the counterclockwise optical signal to obtain the filtered counterclockwise optical signal.
[0035] The fourth filter is used to receive the modulated second optical signal, filter the modulated second optical signal to obtain the second optical signal after secondary filtering; it is also used to receive the clockwise optical signal, filter the clockwise optical signal to obtain the filtered clockwise optical signal.
[0036] The ring is used to receive the first optical signal and the second optical signal after secondary filtering. The first optical signal and the second optical signal after secondary filtering rotate clockwise and counterclockwise respectively. After rotating several times, the clockwise optical signal and the counterclockwise optical signal are emitted from the ring.
[0037] The detector is used to receive the interfering optical signal, and to perform photoelectric conversion on the interfering optical signal to obtain the phase difference electrical signal.
[0038] To gain a further understanding of the present invention, the following description is provided in conjunction with... Figure 1 and Figure 2 The silicon photonic gyroscope of the present invention, with its coated mode-filtered dual Y-waveguide integrated structure, is described in detail.
[0039] like Figure 1 As shown, a silicon photonic gyroscope with a coated mode-filtering dual-Y waveguide integrated structure includes a laser, a detector, a symmetrical dual-Y waveguide, a first filter 1, a second filter 2, a third filter 3, a fourth filter 4, a first phase modulator, a second phase modulator, and a loop. Filters 1 and 2 are located at the output end of the symmetrical dual-Y waveguide to suppress higher-order modes excited during the beam splitting process. Filters 3 and 4 are located after the phase modulation region to prevent the introduction of new modes by temperature gradients or stress. The four filters are based on a coated structure and achieve selective suppression of higher-order spatial modes through multilayer dielectric thin films.
[0040] In this embodiment, the first filter, the second filter, the third filter, and the fourth filter are all coated spatial mode filters, and from bottom to top they are a lower cladding layer, a lower thin film, a spacer layer, an upper thin film, and an upper cladding layer. The lower cladding layer, the spacer layer, and the upper cladding layer are all made of SiO2 material, and the lower thin film and the upper thin film are both made of Si3N4 material, as shown in Table 1.
[0041] Table 1. Five-layer filter structure
[0042]
[0043] like Figure 2 The diagram shown is a flowchart of the overall process of a silicon photonic gyroscope filter, which includes the following steps:
[0044] (1) Preparatory work
[0045] Prerequisites: SOI substrate (top silicon 220nm, buried oxide layer 3μm), dual Y waveguides have been completed by electron beam lithography or 193nm lithography + ICP-RIE dry etching, waveguide sidewalls are smooth, RMS roughness <2nm (AFM measurement). Ensure that there is no residual photoresist or etching damage in the Y junction region.
[0046] (2) Surface cleaning
[0047] The process includes: RCA1 cleaning (removing organic matter), RCA2 cleaning (removing metal ions), and dilute HF rinsing (removing the natural oxide layer). After cleaning, the material is immediately transferred to the deposition equipment to prevent re-oxidation.
[0048] (3) PECVD deposition of SiO2 cladding (2000nm)
[0049] Isolate the waveguide from subsequent films and provide a flat substrate.
[0050] (4) LPCVD deposition of the first layer of Si3N4 (180nm)
[0051] Use LPCVD instead of PECVD to achieve higher density and lower H content; high temperature compatibility with SOI temperature resistance is required (generally <800℃ for safety).
[0052] (5) PECVD deposition of SiO2 spacer layer (90nm)
[0053] Adjust the optical path in the vertical direction to create FP interference conditions.
[0054] (6) LPCVD deposition of a second layer of Si3N4 (180nm)
[0055] The cladding must completely cover all components to prevent pinhole or step breakage.
[0056] (7) PECVD deposition of SiO2 cladding (≥1500nm)
[0057] Ensure the cladding completely covers all components to prevent pinhole or step breakage.
[0058] (8) High-temperature annealing treatment
[0059] Avoid temperatures exceeding 500°C to prevent Si3N4 crystallization or SOI delamination.
[0060] (9) Chemical mechanical polishing (CMP).
[0061] (10) Electrode preparation.
[0062] (11) Packaging test.
[0063] The silicon photonic gyroscope of the present invention improves zero-position drift as follows:
[0064] Let the zero-position drift before filtering be:
[0065] Ω bias =8.7×10 -2 (Unit: ° / h)
[0066] After introducing the filter, residual mode interference is reduced, and the residual null drift of the silicon photonic gyroscope is:
[0067]
[0068] Among them, Ω'bias λ is the zero-point drift after filtering, λ is the operating wavelength, c is the speed of light in vacuum, A is the effective area enclosed by the interference loop, and δφ is the zero-point drift after filtering. res This represents the residual non-ideal phase shift.
[0069] The optimized zero-position error calculation is as follows:
[0070] Ω' bias =6.3×10 -2 (Unit: ° / h)
[0071] The improvement factor reaches 138 times, meeting the requirements of high-precision navigation.
[0072] In summary, this invention provides a silicon photonic gyroscope with a coated mode-filtering dual-Y-waveguide integrated structure. The symmetrical dual-Y-waveguides employ a symmetrical optimization design, achieved through collaborative optimization of the two Y-waveguides to reduce mode excitation. The bifurcation angle between the front and rear Y-waveguides is controlled within 8–12°, keeping the higher-order mode excitation rate below 1%, thereby significantly reducing spatial radiation mode error (SRME) and null drift. The first and second filters suppress higher-order modes excited during beam splitting, while the third and fourth filters prevent the introduction of new modes by temperature gradients or stress. The coated filter structure achieves selective suppression of higher-order spatial modes while maintaining low-loss transmission of the fundamental mode, significantly improving the zero-bias stability and measurement accuracy of the silicon photonic gyroscope. This invention is applicable to high-precision inertial measurement scenarios such as SOI (Silicon-on-Insulator) platforms, aerospace, unmanned systems, and intelligent navigation.
[0073] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.
[0074] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.
[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A silicon photonic gyroscope with a coated mode-filtered dual Y-waveguide integrated structure, characterized in that, It includes a laser, a detector, a symmetrical double Y-waveguide, a first filter, a second filter, a third filter, a fourth filter, a first phase modulator, a second phase modulator, and a loop; The laser is used to emit laser light; The first port of the symmetrical double Y waveguide is used to receive laser light, and the first optical signal is emitted from the third port and the second optical signal is emitted from the fourth port; the third port of the symmetrical double Y waveguide is used to receive the counterclockwise optical signal after secondary filtering, the fourth port is used to receive the clockwise optical signal after secondary filtering, and the interference-enhanced optical signal is emitted from the second port. The first filter is used to receive a first optical signal, filter the first optical signal to obtain a filtered first optical signal; it is also used to receive a modulated counterclockwise optical signal, filter the modulated counterclockwise optical signal to obtain a second-filtered counterclockwise optical signal. The second filter is used to receive the second optical signal, filter the second optical signal to obtain the filtered second optical signal; it is also used to receive the modulated clockwise optical signal, filter the modulated clockwise optical signal to obtain the second filtered clockwise optical signal. The first phase modulator is used to receive the filtered first optical signal, perform phase modulation on the filtered first optical signal to obtain the modulated first optical signal; it is also used to receive the filtered counterclockwise optical signal, perform phase modulation on the filtered counterclockwise optical signal to obtain the modulated counterclockwise optical signal. The second phase modulator is used to receive the filtered second optical signal, perform phase modulation on the filtered second optical signal to obtain the modulated second optical signal; it is also used to receive the filtered clockwise optical signal, perform phase modulation on the filtered clockwise optical signal to obtain the modulated clockwise optical signal. The third filter is used to receive the modulated first optical signal, filter the modulated first optical signal to obtain the second filtered first optical signal; it is also used to receive the counterclockwise optical signal, filter the counterclockwise optical signal to obtain the filtered counterclockwise optical signal. The fourth filter is used to receive the modulated second optical signal, filter the modulated second optical signal to obtain the second optical signal after secondary filtering; it is also used to receive the clockwise optical signal, filter the clockwise optical signal to obtain the filtered clockwise optical signal. The ring is used to receive the first optical signal and the second optical signal after secondary filtering. The first optical signal and the second optical signal after secondary filtering rotate clockwise and counterclockwise respectively. After rotating several times, the clockwise optical signal and the counterclockwise optical signal are emitted from the ring. The detector is used to receive the interfering optical signal and perform photoelectric conversion on the interfering optical signal to obtain the phase difference electrical signal. Among them, the first filter, the second filter, the third filter, and the fourth filter are all coated spatial mode filters.
2. The silicon photonic gyroscope according to claim 1, characterized in that, Each coated spatial mode filter consists of a lower cladding layer, a lower thin film, a spacer layer, an upper thin film, and an upper cladding layer from bottom to top. The lower cladding layer, the spacer layer, and the upper cladding layer are all made of SiO2 material, while the lower thin film and the upper thin film are both made of Si3N4 material.
3. The silicon photonic gyroscope according to claim 1, characterized in that, The thickness of the lower cladding layer is 2000 nm, the thickness of the lower thin film is 180 nm, the thickness of the spacer layer is 90 nm, the thickness of the upper thin film is 180 nm, and the thickness of the upper cladding layer is greater than or equal to 1500 nm.
4. The silicon photonic gyroscope according to claim 1, characterized in that, The bifurcation angles of the first and second ports of the symmetrical double Y waveguide range from 8 to 12°, and the bifurcation angles of the third and fourth ports range from 8 to 12°.