Optical waveguide sensor, preparation method and device thereof and detection method

Abstract

The invention provides an optical waveguide sensor, a preparation method and device thereof and a detection method. The optical waveguide sensor comprises a coupling module and an interference module. The coupling module comprises a first coupler and a second coupler, and the interference module is located between the first coupler and the second coupler; the interference module comprises a sensing arm and a reference arm; the first output end of the first coupler is connected with the first end of the sensing arm, and the second output end of the first coupler is connected with the first end of the reference arm; the first input end of the second coupler is connected with the second end of the sensing arm, and the second input end of the second coupler is connected with the second end of the reference arm; wherein the sensing arm comprises a first nonlinear tapered waveguide structure, a first spot-size conversion waveguide structure, a sensing waveguide structure, a second spot-size conversion waveguide structure and a second nonlinear tapered waveguide structure which are sequentially and adjacently arranged; according to the optical waveguide sensor provided by the invention, the detection precision of the sensor is effectively improved by designing a plurality of waveguide structures on the sensing arm.

Description

Technical Field

[0001] The embodiments of the present invention relate to the fields of optical waveguide technology and optical sensor technology, and in particular to an optical waveguide sensor and a preparation method, device and detection method thereof. Background Art

[0002] Waveguide optical sensor is an optical sensor based on on-chip waveguide structure. Optical sensor is widely used because of its good sensitivity performance due to the interaction between the on-chip strip waveguide and the light field contacting the analyte. In order to better meet people's needs, it is necessary to continuously improve the sensing accuracy of the sensor. Summary of the invention

[0003] The embodiment of the present invention provides an optical waveguide sensor and a preparation method, device and detection method thereof, which effectively improves the detection accuracy of the sensor by designing multiple waveguide structures on a sensor arm.

[0004] In a first aspect, an embodiment of the present invention provides an optical waveguide sensor, including a coupling module and an interference module;

[0005] The coupling module includes a first coupler and a second coupler, and the interference module is located between the first coupler and the second coupler;

[0006] The interference module includes a sensing arm and a reference arm;

[0007] The first coupler includes a first output end and a second output end, the first output end is connected to the first end of the sensing arm, and the second output end is connected to the first end of the reference arm; the second coupler includes a first input end and a second input end, the first input end is connected to the second end of the sensing arm, and the second input end is connected to the second end of the reference arm;

[0008] Wherein, the sensing arm comprises a first nonlinear gradual change waveguide structure, a first mode spot conversion waveguide structure, a sensing waveguide structure, a second mode spot conversion waveguide structure and a second nonlinear gradual change waveguide structure which are arranged adjacent to each other in sequence; the first nonlinear gradual change waveguide structure is close to the first end of the sensing arm, the first mode spot conversion waveguide structure is located on a side of the first nonlinear gradual change waveguide structure away from the first end of the sensing arm, the sensing waveguide structure is located on a side of the first mode spot conversion waveguide structure away from the first nonlinear gradual change waveguide structure, the second mode spot conversion waveguide structure is located on a side of the sensing waveguide structure away from the first mode spot conversion waveguide structure, the second nonlinear gradual change waveguide structure is located on a side of the second mode spot conversion waveguide structure away from the sensing waveguide structure, and the second nonlinear gradual change waveguide structure is close to the second end of the sensing arm.

[0009] In a second aspect, an embodiment of the present invention provides a method for preparing an optical waveguide sensor, which is used to prepare the optical waveguide sensor according to the first aspect, and is characterized in that the preparation method comprises:

[0010] An interference module is prepared, wherein the interference module comprises a sensing arm and a reference arm; the sensing arm comprises a first nonlinear gradient waveguide structure, a pattern spot conversion waveguide structure, a sensing waveguide structure, and a second nonlinear gradient waveguide structure which are arranged adjacent to each other in sequence; the first nonlinear gradient waveguide structure is close to the first end of the sensing arm, the first pattern spot conversion waveguide structure is located on a side of the first nonlinear gradient waveguide structure away from the first end of the sensing arm, the sensing waveguide structure is located on a side of the first pattern spot conversion waveguide structure away from the first nonlinear gradient waveguide structure, the second pattern spot conversion waveguide structure is located on a side of the sensing waveguide structure away from the first pattern spot conversion waveguide structure, the second nonlinear gradient waveguide structure is located on a side of the second pattern spot conversion waveguide structure away from the sensing waveguide structure, and the second nonlinear gradient waveguide structure is close to the second end of the sensing arm;

[0011] The control coupling module is connected to the interference module; the first coupler includes a first output end and a second output end, the first output end is connected to the first end of the sensor arm, and the second output end is connected to the first end of the reference arm; the second coupler includes a first input end and a second input end, the first input end is connected to the second end of the sensor arm, and the second input end is connected to the second end of the reference arm.

[0012] In a third aspect, an embodiment of the present invention provides an optical waveguide sensor device, comprising the optical waveguide sensor described in the first aspect and a laser, wherein the laser is connected to an input end of the first coupler.

[0013] In a fourth aspect, an embodiment of the present invention provides a detection method for an optical waveguide sensor device, including the optical waveguide sensor device according to the third aspect, and the detection method includes:

[0014] Controlling the laser to input light into the first coupler, and inputting the light into the sensor arm and the reference arm through the first output end and the second output end of the first coupler;

[0015] Control the gas to be measured to interact with the light in the sensing waveguide structure;

[0016] calculating a phase difference between the light transmitted from the reference arm to the second coupler and the light transmitted from the sensor to the second coupler;

[0017] The concentration of the gas to be measured is determined according to the phase difference.

[0018] The embodiment of the present invention provides an optical waveguide sensor, the optical waveguide sensor includes a coupling module and an interference module, wherein the coupling module includes a first coupler and a second coupler, and the interference module is located between the first coupler and the second coupler; further, the interference module includes a sensing arm and a reference arm, wherein the gas to be detected acts at the sensing arm, and the reference arm is used as a reference group to detect the gas to be detected. Wherein, the sensing arm includes a first nonlinear gradient waveguide structure, a first mode spot conversion waveguide structure, a sensing waveguide structure, a second mode spot conversion waveguide structure, and a second nonlinear gradient waveguide structure, which are arranged adjacent to each other in sequence. Through the Mach-Zehnder interferometer (MZI) of the sensing arm integrated slot waveguide, that is, the realization of the MZI type optical waveguide sensor, and the structural enrichment design of the sensing arm, the detection accuracy of the optical waveguide sensor can be effectively improved, and the length of the required optical waveguide can be effectively reduced under the condition of the same sensing sensitivity requirement, thereby reducing the overall volume and material and manufacturing costs of the optical waveguide sensor, improving the convenience of use, and making it easier to integrate into various terminal electronic devices.

[0019] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required to describe the embodiments. Obviously, the drawings introduced are only drawings of a part of the embodiments to be described in the present invention, rather than all the drawings. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 is a schematic structural diagram of an optical waveguide sensor provided by an embodiment of the present invention;

[0022] Figure 2 yes Figure 1 A magnified schematic diagram of the middle sensing arm;

[0023] Figure 3 yes Figure 2 A schematic cross-sectional view along the section line A-A';

[0024] Figure 4 yes Figure 2 A schematic cross-sectional view along the section line BB';

[0025] Figure 5 yes Figure 2 A schematic cross-sectional view along the section line C-C';

[0026] Figure 6 is a schematic structural diagram of another optical waveguide sensor provided by an embodiment of the present invention;

[0027] Figure 7 yes Figure 6 A magnified schematic diagram of the middle sensing arm;

[0028] Figure 8 is a flow chart of a method for preparing an optical waveguide sensor provided by an embodiment of the present invention;

[0029] Fig. 9 is a flow chart of another method for preparing an optical waveguide sensor provided by an embodiment of the present invention;

[0030] Fig.10 is a diagram of a process for preparing a sensor arm in an optical waveguide sensor provided by an embodiment of the present invention;

[0031] Fig.11 is a diagram of the preparation process of a sensor arm in another optical waveguide sensor provided by an embodiment of the present invention;

[0032] Fig.12 is a diagram of the preparation process of a sensor arm in another optical waveguide sensor provided by an embodiment of the present invention;

[0033] Fig.13 is a schematic structural diagram of an optical waveguide sensing device provided by an embodiment of the present invention;

[0034] Fig.14 It is a flow chart of a detection method of an optical waveguide sensor device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It will be appreciated that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts of the present invention, rather than all structures, are shown in the accompanying drawings. It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0036] Figure 1 is a schematic structural diagram of an optical waveguide sensor provided by an embodiment of the present invention, Figure 2 yes Figure 1 Enlarged schematic diagram of the middle sensor arm, see Figure 1 and Figure 2As shown, an embodiment of the present invention provides an optical waveguide sensor 10, which includes a coupling module 100 and an interference module 200; the coupling module 100 includes a first coupler 110 and a second coupler 120, and the interference module 200 is located between the first coupler 110 and the second coupler 120; the interference module 200 includes a sensing arm 210 and a reference arm 220; the first coupler 110 includes a first output end 110a and a second output end 110b, the first output end 110a is connected to the first end 210a of the sensing arm, and the second output end 110b is connected to the first end 220a of the reference arm; the second coupler 120 includes a first input end 120a and a second input end 120b, the first input end 120a is connected to the second end 210b of the sensing arm, and the second input end 120b is connected to the second end 220b of the reference arm; wherein the sensing arm 210 includes a first input end 120a and a second input end 120b, the first input end 120a is connected to the second end 210b of the sensing arm, and the second input end 120b is connected to the second end 220b of the reference arm; A nonlinear gradual change waveguide structure 211, a first pattern spot conversion waveguide structure 212, a sensing waveguide structure 213, a second pattern spot conversion waveguide structure 214 and a second nonlinear gradual change waveguide structure 215; the first nonlinear gradual change waveguide structure 211 is close to the first end 210a of the sensing arm, the first pattern spot conversion waveguide structure 212 is located on a side of the first nonlinear gradual change waveguide structure 211 away from the first end 210a of the sensing arm, the sensing waveguide structure 213 is located on a side of the first pattern spot conversion waveguide structure 212 away from the first nonlinear gradual change waveguide structure 211, the second pattern spot conversion waveguide structure 214 is located on a side of the sensing waveguide structure 213 away from the first pattern spot conversion waveguide structure 212, the second nonlinear gradual change waveguide structure 215 is located on a side of the second pattern spot conversion waveguide structure 214 away from the sensing waveguide structure 213, and the second nonlinear gradual change waveguide structure 215 is close to the second end 210b of the sensing arm.

[0037] Among them, reference Figure 1 As shown, the optical waveguide sensor 10 includes a coupling module 100 and an interference module 200, wherein the coupling module 100 includes a first coupler 110 and a second coupler 120, and the interference module 200 includes a sensing arm 210 and a reference arm 220. The first coupler 110 and the second coupler 120 are located on both sides of the interference module 200. The first coupler 110 includes two output ports, wherein the first output end 110a of the first coupler 110 is connected to the sensing arm 210, and the second output end 110b of the first coupler 110 is connected to the reference arm 220; the second coupler 120 includes two input ports, wherein the first input port 120a of the second coupler 120 is connected to the sensing arm 210, and the second input port 120b of the second coupler 120 is connected to the reference arm 220, thereby realizing that the sensing arm 210 and the reference arm 220 in the interference module 200 are arranged between the first coupler 110 and the second coupler 120.

[0038] For the specific connection relationship between the interference module 200 and the coupling module 100, please refer to Figure 1 As shown, the first output end 110a of the first coupler 110 is connected to the first end 210a of the sensing arm 210, and the second output end 110b of the first coupler 110 is connected to the first end 220a of the reference arm 220; the first input end 120a of the second coupler 120 is connected to the second end 210b of the sensing arm 210, and the second input end 120b of the second coupler 120 is connected to the second end 220b of the reference arm 220.

[0039] Furthermore, the optical waveguide sensor 10 detects the gas to be measured by means of an optical waveguide. An optical waveguide is a medium device that guides light waves to propagate therein, also known as a dielectric optical waveguide. The optical waveguide is transmitted through a waveguide structure. Among them, the first coupler 110 can also ensure that at least one input port ( Figure 1 The input port transmits the light to the first coupler 110. The light received by the first coupler 110 can be transmitted to the sensing arm 210 and the reference arm 220 through two output ports, wherein the sensing arm 210 and the reference arm 220 are waveguide structures. The light transmitted at the sensing arm 210 interacts with the gas to be measured, such as the refractive index of the light changes, etc.; while the light transmitted at the reference arm 220 remains in its original state. The second coupler 120 also includes at least two output ports ( Figure 1 The second coupler 120 is used to output the light transmitted in the reference arm 220 and the sensor arm 210. By comparing the two lights output by the second coupler 120, such as comparing the light intensity, etc., combined with the light judgment, the optical waveguide sensor 10 can detect the gas to be measured.

[0040] Or it can be understood that the basic principle of the optical waveguide sensor 10 is that the waveguide structure at the sensing waveguide structure 213 interacts with external gas molecules to change the light transmission characteristics. Therefore, during the sensing detection process of the optical waveguide sensor 10, the reference arm 220 is placed in the air, and the sensing arm 210 is used to introduce the gas to be measured. The concentration of the gas to be measured is calculated by the light field intensity ratio after the interference of the output light on both sides. When the optical waveguide transmitted in the sensing waveguide structure 213 interacts with the gas to be measured, or is called coupling, the overall structure of the sensing waveguide structure 213 is an important indicator that affects the coupling loss. By adjusting the structure of the sensing waveguide structure 213, the detection accuracy of the gas to be measured can be improved.

[0041] Among them, reference Figure 1 and Figure 2As shown, the sensing arm 210 includes a first nonlinear gradual change waveguide structure 211, a first spot conversion waveguide structure 212, a sensing waveguide structure 213, a second spot conversion waveguide structure 214, and a second nonlinear gradual change waveguide structure 215, and the first nonlinear gradual change waveguide structure 211, the first spot conversion waveguide structure 212, the sensing waveguide structure 213, the second spot conversion waveguide structure 214, and the second nonlinear gradual change waveguide structure 215 are waveguide structures arranged adjacent to each other in sequence. Specifically, along the direction from the first coupler 110 to the second coupler 120, the waveguide structures in the sensing arm 210 are: the first nonlinear gradual change waveguide structure 211, the first spot conversion waveguide structure 212, the sensing waveguide structure 213, the second spot conversion waveguide structure 214, and the second nonlinear gradual change waveguide structure 215 in sequence. By enriching the waveguide structure in the sensing arm 210 , it is possible to ensure that the sensing arm 210 interacts better with the gas to be measured, thereby ensuring the detection accuracy of the optical waveguide sensor 10 for the gas to be measured.

[0042] Furthermore, the light transmitted to the sensing arm 210 through the first coupler 110 can first pass through the first nonlinear gradient waveguide structure 211 to realize the conversion of the light field mode, for example, from TE0 to TE1 or to TE2, that is, the fundamental mode of the transverse electric mode is converted to the high-order mode of the transverse electric mode, wherein TE0, TE1 and TE2 represent different modes of the light field. Furthermore, after passing through the first nonlinear gradient waveguide structure 211, the light is transmitted to the sensing waveguide structure 213 through the first mode spot conversion waveguide structure 212, and interacts with the gas to be measured at the sensing waveguide structure 210. The light can adjust the number of light transmission paths and the size of the light spot in the first mode spot conversion waveguide structure 212, thereby ensuring a better interaction effect between the light and the gas to be measured at the sensing waveguide structure 210. Furthermore, the sensing arm 210 also includes a second spot conversion waveguide structure 214 and a second nonlinear gradient waveguide structure 215. The second spot conversion waveguide structure 214 is used to adjust the light after reacting with the gas to be measured back to the number of transmission paths and the spot size of the light when it was originally transmitted to the first spot conversion waveguide structure 212, and then adjust the light field mode of the light back to the original light field mode through the second nonlinear gradient waveguide structure 215, for example, from TE1 or TE2 to TE0, that is, the high-order mode of the transverse electric mode is converted to the fundamental mode of the transverse electric mode. The first nonlinear gradient waveguide structure 211 and the first spot conversion waveguide structure 212 can ensure that the light transmitted to the sensing waveguide structure 213 fully interacts with the gas to be measured, which can also be understood as adjusting the transmission effect of the light through the cooperation of the nonlinear gradient waveguide structure and the spot conversion waveguide structure. The light can be adjusted back to its original mode through the second mode spot conversion waveguide structure 214 and the second nonlinear gradient waveguide structure 215 to ensure the correspondence between the light emitted by the sensing arm 210 and the light emitted by the reference arm 220, thereby facilitating the comparison of parameters such as light intensity. Combined with the light judgment, the optical waveguide sensor 10 can detect the gas to be tested.

[0043] Further, the waveguide structures arranged adjacent to each other in the sensing arm 210 can be understood as the sensing waveguide structure 213 being the center, the first mode spot conversion waveguide structure 212 and the second mode spot conversion waveguide structure 214 being symmetrically arranged, and the first nonlinear gradient waveguide structure 211 and the second nonlinear gradient waveguide structure 215 being symmetrically arranged. By utilizing the different modes transmitted in the sensing arm 210 and the reference arm 220, the sensitivity of the optical waveguide sensor 10 can be improved under a limited arm length.

[0044] In summary, an embodiment of the present invention provides an optical waveguide sensor, wherein the interference module includes a sensing arm and a reference arm, wherein the gas to be detected acts on the sensing arm, and the reference arm serves as a reference group to detect the gas to be detected. Furthermore, the sensing arm includes a first nonlinear gradient waveguide structure, a first pattern spot conversion waveguide structure, a sensing waveguide structure, a second pattern spot conversion waveguide structure, and a second nonlinear gradient waveguide structure, which are arranged adjacent to each other in sequence. By enriching the structure of the sensing arm, the detection accuracy of the optical waveguide sensor can be effectively improved.

[0045] Figure 3 yes Figure 2 A schematic cross-sectional view along the section line A-A', Figure 4 yes Figure 2 A schematic cross-sectional view along the section line B-B', Figure 5 yes Figure 2 A schematic cross-sectional view along the section line C-C', see Figures 1 to 5 As shown, the optical waveguide sensor 10 includes a substrate 300 and a cladding 400, the cladding 400 includes a first cladding 410 and a second cladding 420, the first cladding 410 is located on one side of the substrate 300, and the second cladding 420 is located on the side of the first cladding 410 away from the substrate 100; the first cladding 410 includes a first groove 411 penetrating the first cladding 410, and the second cladding 420 includes a second groove 421 penetrating the second cladding 420, and the orthographic projection of the first groove 411 onto the substrate 300 overlaps with the orthographic projection of the second groove 421 onto the substrate 300; along the thickness direction X1 of the substrate 300, the reference arm 220, the first nonlinear gradient waveguide structure 211, the first mode spot conversion waveguide structure 212, the second mode spot conversion waveguide structure 214 and the second nonlinear gradient waveguide structure 215 are located on the first between the cladding 410 and the second cladding 420; along the direction X2 pointing from the first coupler 110 to the second coupler 120, the projection of the sensing waveguide structure 213 at least partially overlaps with the projection of the first spot conversion waveguide structure 212; the orthographic projection of the sensing waveguide structure 213 onto the substrate 400 at least partially overlaps with the orthographic projection of the first groove 411 onto the substrate 400; the sensing waveguide structure 213 includes a first waveguide 213a and a second waveguide 213b, the first waveguide first end 213a1 is connected to the first spot conversion waveguide structure 212, the second waveguide first end 213b1 is connected to the first spot conversion waveguide structure 213; the first waveguide second end 213a2 is connected to the second spot conversion waveguide structure 214, and the second waveguide second end 213b2 is connected to the second non-spot conversion waveguide structure 214.

[0046] For further reference, Figures 2 to 5As shown, the optical waveguide sensor 10 includes a substrate 300 , and a cladding 400 is disposed on one side of the substrate 300 . The cladding 400 includes a first cladding 410 and a second cladding 420 . The first cladding 410 and the second cladding 420 are used to cover the waveguide structure.

[0047] Specifically, the reference arm 220, the first nonlinear gradient waveguide structure 211, the first spot conversion waveguide structure 212, the second spot conversion waveguide structure 214 and the second nonlinear gradient waveguide structure 215 are located between the first cladding 410 and the second cladding 420. It can also be understood that the first cladding 410 and the second cladding 420 cover the reference arm 220, the first nonlinear gradient waveguide structure 211, the first spot conversion waveguide structure 212, the second spot conversion waveguide structure 214 and the second nonlinear gradient waveguide structure 215. Exemplarily, the reference arm 220, the first nonlinear gradient waveguide structure 211, the first spot conversion waveguide structure 212, the second spot conversion waveguide structure 214 and the second nonlinear gradient waveguide structure 215 are covered by the first cladding 410 and the second cladding 420. Figure 2 and Figure 3 As shown, Figure 3 The positional relationship between the first nonlinear gradient waveguide structure 211 and the first cladding 410 and the second cladding 420 is shown in the figure. Similarly, the setting positions of the reference arm 220, the first mode spot conversion waveguide structure 212, the second mode spot conversion waveguide structure 214 and the second nonlinear gradient waveguide structure 215 are similar and are not shown one by one by examples.

[0048] For further reference, Figure 2 As shown, the sensing waveguide structure 213 includes a first waveguide 213a and a second waveguide 213b. When light is transmitted to the sensing waveguide structure 213, the light continues to be transmitted through the first waveguide 213a and the second waveguide 213b. Alternatively, it can be understood that two waveguide structures are provided at the sensing waveguide structure 213 to improve the interaction efficiency between light and the gas to be measured. Among them, the first end 213a1 of the first waveguide is connected to the first spot conversion waveguide structure 212, and the second end 213a2 of the first waveguide is connected to the second spot conversion waveguide structure 214, so that the first waveguide 213a exists between the first spot conversion waveguide structure 212 and the second spot conversion waveguide structure 214; similarly, the first end 213b1 of the second waveguide is connected to the first spot conversion waveguide structure 213, and the second end 213b2 of the second waveguide is connected to the second non-spot conversion waveguide structure 214, so that the second waveguide 213b exists between the first spot conversion waveguide structure 212 and the second spot conversion waveguide structure 214. Moreover, along the direction X2 from the first coupler 110 to the second coupler 120, the projection of the sensing waveguide structure 213 at least partially overlaps with the projection of the first spot conversion waveguide structure 212, which can be understood as the first waveguide 213a and the second waveguide 213b are prepared in the same layer as the remaining waveguide structures, combined with Figures 3 to 5 As shown ( Figure 5The second waveguide 213b is used as an example), the sensing waveguide structure 213 and the first spot conversion waveguide structure 212 are arranged on the same layer, and the sensing waveguide structure 213 and the first nonlinear gradient waveguide structure 211 are also arranged on the same layer.

[0049] For further reference, Figure 2 , Figure 4 and Figure 5 As shown, the first cladding layer 410 includes a first groove 411, and the first groove 411 penetrates the first cladding layer 410, so the substrate 300 can be exposed through the first groove 411. The second cladding layer 420 includes a second groove 421, and the second groove 421 penetrates the second cladding layer 420, and the orthographic projection of the first groove 411 to the substrate 300 overlaps with the orthographic projection of the second groove 421 to the substrate 300, so the substrate 300 can be exposed through the second groove 421 and the first groove 411.

[0050] The orthographic projection of the sensing waveguide structure 213 onto the substrate 400 at least partially overlaps with the orthographic projection of the first groove 411 onto the substrate 400. Figure 2 , Figure 4 and Figure 5 As shown, the first waveguide 213a and the second waveguide 213b are suspended in the space formed by the first groove 411 and the second groove 421, and are connected to the first mode spot conversion waveguide structure and the second mode spot conversion waveguide structure as the suspended support points of the first waveguide 213a and the second waveguide 213b. This can be understood as the sensing waveguide structure 213 being arranged in the groove region formed by the first cladding 410 and the second cladding 420.

[0051] In the optical waveguide sensor 10 provided by the embodiment of the present invention, the sensing waveguide structure 213 in the sensing arm 210 is arranged in a groove, that is, the first waveguide 213a and the second waveguide 213b are arranged in the groove, and the groove waveguide structure is used to maximize the cladding evanescent field limitation factor. The concentration of the gas to be measured is analyzed by the interference result with the optical signal in the reference arm 220, thereby improving the detection accuracy of the gas to be measured.

[0052] Optionally, the material of the waveguide structure may be silicon, that is, the material of the first waveguide 213a and the second waveguide 213b may be silicon. The material of the substrate 300 and the cladding 400 may be silicon oxide.

[0053] Among them, due to the high refractive index of silicon oxide materials, in order to improve the efficient interaction between the transmitted light in the sensing waveguide structure 213 and the gas molecules of the gas to be measured, the first waveguide 213a and the second waveguide 213b are set. There are slits in the first waveguide 213a and the second waveguide 213b. By setting the slit waveguide, the light field is transmitted between the first waveguide 213a and the second waveguide 213b. The waveguide structure in the sensing waveguide structure 213 is further optimized by the time domain differential finite element method, thereby improving the degree of interaction between the gas molecules and the light in the waveguide structure. Specifically, the purpose of setting the first nonlinear gradient waveguide structure 211 is to effectively couple the external laser to the inside of the optical waveguide sensor 10, reduce the coupling loss and thus reduce the power consumption of the system. It can also be combined with the first mode spot conversion waveguide structure 212 to reduce the structural difference due to the slit waveguide, thereby significantly improving the coupling efficiency, thereby ensuring the effect of the sensing waveguide structure 213 and the gas to be measured, and improving the detection accuracy of the optical waveguide sensor 10.

[0054] Continue to refer Figure 2 and Figure 4 As shown, along the first direction X3, the gap between the first waveguide 213a and the second waveguide 213b is d, wherein 0.1 micron≤d≤0.3 micron, and the first direction is perpendicular to the transmission direction of the optical waveguide in the sensing waveguide structure.

[0055] Further, along the first direction X3, the gap between the first waveguide 213a and the second waveguide 213b is d. And d satisfies: 0.1 micron ≤ d ≤ 0.3 micron. The specific parameters of the gap d can be adaptively adjusted in combination with the sizes of the first waveguide 213a and the second waveguide 213b. For example, along the first direction X3, when the width of the first waveguide 213a is 0.52 micron, the gap d can be 0.2 micron, at which time the cladding confinement factor is maximum (the light energy is maximally distributed in the gap between the first waveguide 213a and the second waveguide 213b), and the transmission loss is minimum, for example, about 1 dB / cm. The specific values ​​can be adjusted according to different actual needs.

[0056] Continue to refer Figure 2As shown, along the direction X2 pointing from the first coupler 110 to the second coupler 120, the length of the first nonlinear gradient waveguide structure 211 is L1, the length of the first mode spot conversion waveguide structure 212 is L2, the length of the sensing waveguide structure 213 is L3, the length of the second mode spot conversion waveguide structure 214 is L4, and the length of the second nonlinear gradient waveguide structure 215 is L5; along the direction X3 perpendicular to the first coupler 110 pointing to the second coupler 120, the length of the first nonlinear gradient waveguide structure 211 is L1, the length of the first mode spot conversion waveguide structure 212 is L2, the length of the sensing waveguide structure 213 is L3, the length of the second mode spot conversion waveguide structure 214 is L4, and the length of the second nonlinear gradient waveguide structure 215 is L5. The width of the first nonlinear gradient waveguide structure 211 away from the first mode spot conversion waveguide structure 212 is W1, the width of the first nonlinear gradient waveguide structure 211 close to the first mode spot conversion waveguide structure 212 is W2, the width of the first mode spot conversion waveguide structure 212 close to the first nonlinear gradient waveguide structure 211 is W3, the width of the first mode spot conversion waveguide structure 212 close to the sensing waveguide structure 213 is W4, the width of the sensing waveguide structure 213 is W5, and the width of the second mode spot conversion waveguide structure 214 close to the sensing waveguide structure 214 is W6. The width of the waveguide structure 213 is W6, the width of the second spot conversion waveguide structure 214 close to the second nonlinear gradient waveguide structure 215 is W7, the width of the second nonlinear gradient waveguide structure 215 close to the second spot conversion waveguide structure 214 is W8, and the width of the second nonlinear gradient waveguide structure 215 away from the second spot conversion waveguide structure 214 is W9; wherein: 500 microns ≤ L1 ≤ 700 microns, 30 microns ≤ L2 ≤ 70 microns, 100 microns ≤ L3 ≤ 300 microns m; 30 μm ≤ L4 ≤ 70 μm, 500 μm ≤ L5 ≤ 700 μm; 0.1 μm ≤ W1 ≤ 0.5 μm, 0.5 μm ≤ W2 ≤ 1.0 μm, 0.5 μm ≤ W3 ≤ 1.0 μm, 1.0 μm ≤ W4 ≤ 1.5 μm, 1.0 μm ≤ W5 ≤ 1.5 μm, 1.0 μm ≤ W6 ≤ 1.5 μm, 0.5 μm ≤ W7 ≤ 1.0 μm, 0.5 μm ≤ W8 ≤ 1.0 μm, 0.1 μm ≤ W9 ≤ 0.5 μm.

[0057] For further reference, Figure 1 and Figure 2As shown, along the direction X2 from the first coupler 110 to the second coupler 120, the length of the first nonlinear gradient waveguide structure 211 is L1, and the length of the second nonlinear gradient waveguide structure 215 is L5, and L1 and L5 satisfy: 500 microns ≤ L1 ≤ 700 microns, 500 microns ≤ L5 ≤ 700 microns, for example, L1 can be 600 microns, and L5 can be 600 microns. Further, in order to ensure the structural regularity of the optical waveguide sensor 10, the length of the first nonlinear gradient waveguide structure 211 can be adjusted to be the same as or similar to the length of the second nonlinear gradient waveguide structure 215. For example, it is calculated that when the lengths of the first nonlinear gradient waveguide structure 211 and the second nonlinear gradient waveguide structure 215 reach 600um, the coupling efficiency gradually stabilizes and the coupling loss is small. At the same time, along the direction X3 perpendicular to the first coupler 110 pointing to the second coupler 120, the first nonlinear gradient waveguide structure 211 and the second nonlinear gradient waveguide structure 215 are waveguide structures with gradient sizes, and their widths away from the sensing waveguide structure 213 are W1 and W9 respectively, and their widths close to the sensing waveguide structure 213 are W2 and W8 respectively, wherein W1 and W9 satisfy: 0.1 micron ≤ W1 ≤ 0.5 micron, 0.1 micron ≤ W9 ≤ 0.5 micron, for example, W1 can be 0.2 micron, W9 can be 0.2 micron, 0.5 micron ≤ W2 ≤ 1.0 micron, 0.5 micron ≤ W8 ≤ 1.0 micron, for example, W2 can be 0.8 micron, and W8 can be 0.8 micron. Further, in order to ensure the structural regularity of the optical waveguide sensor 10, the width of the first nonlinear gradient waveguide structure 211 can be adjusted to be the same as or similar to the width of the second nonlinear gradient waveguide structure 215.

[0058] For further reference, Figure 1 and Figure 2As shown, along the direction X2 from the first coupler 110 to the second coupler 120, the length of the first spot conversion waveguide structure 212 is L2, and the length of the second spot conversion waveguide structure 214 is L4, and L2 and L4 satisfy: 30 microns ≤ L2 ≤ 70 microns, 30 microns ≤ L4 ≤ 70 microns, for example, L2 can be 50 microns, and L4 can be 50 microns. Further, in order to ensure the structural regularity of the optical waveguide sensor 10, the length of the first spot conversion waveguide structure 212 can be adjusted to be the same as or similar to the length of the second spot conversion waveguide structure 214. For example, it is calculated that when the lengths of the first spot conversion waveguide structure 212 and the second spot conversion waveguide structure 214 reach 50um, the transmission effect of the optical waveguide is high. At the same time, along the direction X3 perpendicular to the first coupler 110 and pointing to the second coupler 120, for the first spot conversion waveguide structure 212 and the second spot conversion waveguide structure 214, their widths away from the sensing waveguide structure 213 are W3 and W7 respectively, and their widths close to the sensing waveguide structure 213 are W4 and W6 respectively, wherein W3 and W7 satisfy: 0.5 micron ≤ W3 ≤ 1.0 micron, 0.5 micron ≤ W7 ≤ 1.0 micron, for example, W3 can be 0.8 micron, W7 can be 0.8 micron; 1.0 micron ≤ W4 ≤ 1.5 micron, 1.0 micron ≤ W6 ≤ 1.5 micron, for example, W4 can be 1.24 micron, W8 can be 1.24 micron. Further, in order to ensure the structural regularity of the optical waveguide sensor 10, the widths of the first spot conversion waveguide structure 212 and the second spot conversion waveguide structure 214 can be adjusted to be the same or similar.

[0059] For further reference, Figure 2 As shown, along the direction X2 from the first coupler 110 to the second coupler 120, the length of the sensing waveguide structure 213 is L3, and L3 satisfies: 100 microns ≤ L3 ≤ 300 microns, and L3 can be 200 microns. Along the direction X3 perpendicular to the first coupler 110 and pointing to the second coupler 120, the width of the sensing waveguide structure 213 is W5, and W5 can satisfy: 1.0 microns ≤ W5 ≤ 1.5 microns, for example, W5 can be 1.24 microns. The specific size of the waveguide structure can also be adaptively adjusted according to actual needs.

[0060] Figure 6 is a schematic structural diagram of another optical waveguide sensor provided by an embodiment of the present invention, Figure 7 yes Figure 6 Enlarged schematic diagram of the middle sensor arm, see Figure 1 and Figure 2 ,refer to Figure 6 and Figure 7 As shown, the sensing waveguide structure 213 includes a straight waveguide structure or a curved waveguide structure.

[0061] For further reference, Figure 1 and Figure 2 As shown, the shape of the sensing waveguide structure 213 in the optical waveguide sensor 10 is linear, that is, the sensing waveguide structure 213 is a linear waveguide structure. The preparation process of the linear waveguide structure is simple, which can reduce the process cost of the optical waveguide sensor 10. Figure 6 and Figure 7 As shown, the shape is curved, that is, the sensing waveguide structure 213 is a curved waveguide structure. The curved waveguide structure can increase the hole contacting the gas to be detected and improve the detection efficiency. Figure 1 , Figure 2 , Figure 6 and Figure 7 As shown, the configuration of the sensing waveguide structure 213 is diverse.

[0062] Based on the same inventive concept, an embodiment of the present invention further provides a method for preparing an optical waveguide sensor. Figure 8 is a flow chart of a method for preparing an optical waveguide sensor provided by an embodiment of the present invention, with reference to Figure 8 As shown, the preparation method comprises:

[0063] S110, preparing an interference module.

[0064] Furthermore, the optical waveguide sensor detects the gas to be measured by means of an optical waveguide, and the optical waveguide is a dielectric device that guides the propagation of light waves therein, also known as a dielectric optical waveguide. The transmission of the optical waveguide is achieved through a waveguide structure. Among them, the interference module includes a sensing arm and a reference arm. Among them, the sensing arm includes a first nonlinear gradient waveguide structure, a first mode spot conversion waveguide structure, a sensing waveguide structure, a second mode spot conversion waveguide structure, and a second nonlinear gradient waveguide structure, and the first nonlinear gradient waveguide structure, the first mode spot conversion waveguide structure, the sensing waveguide structure, the second mode spot conversion waveguide structure, and the second nonlinear gradient waveguide structure are waveguide structures arranged adjacent to each other in sequence. By enriching the waveguide structure in the sensing arm, it can be ensured that the effect of the sensing arm and the gas to be measured is better, thereby ensuring the detection accuracy of the optical waveguide sensor on the gas to be measured.

[0065] S120, controlling the coupling module to be connected to the interference module.

[0066] The optical waveguide sensor further includes a coupling module and an interference module, wherein the coupling module includes a first coupler and a second coupler, and the first coupler and the second coupler are adjusted to be located on both sides of the interference module. The first coupler includes two output ports, wherein the first output end of the first coupler is connected to the sensing arm, and the second output end of the first coupler is connected to the reference arm; the second coupler includes two input ports, wherein the first input port of the second coupler is connected to the sensing arm, and the second input port of the second coupler is connected to the reference arm, thereby realizing that the sensing arm and the reference arm in the interference module are arranged between the first coupler and the second coupler.

[0067] For the specific connection relationship between the interference module 200 and the coupling module 100, please refer to Figure 1 As shown, the first output end 110a of the first coupler 110 is connected to the first end 210a of the sensing arm 210, and the second output end 110b of the first coupler 110 is connected to the first end 220a of the reference arm 220; the first input end 120a of the second coupler 120 is connected to the second end 210b of the sensing arm 210, and the second input end 120b of the second coupler 120 is connected to the second end 220b of the reference arm 220.

[0068] Among them, the first coupler can also ensure at least one input port, and the input port transmits the light to the first coupler. The light received by the first coupler can be transmitted to the sensor arm and the reference arm respectively through two output ports, wherein the sensor arm and the reference arm are waveguide structures. The light transmitted at the sensor arm interacts with the gas to be measured, for example, the refractive index of the light changes, etc.; while the light transmitted at the reference arm 220 maintains its original state. The second coupler also includes at least two output ports, and the second coupler 120 is used to output the light transmitted in the reference arm and the sensor arm. By comparing the two lights output by the second coupler, such as comparing the light intensity, etc., combined with the judgment of the light, the optical waveguide sensor can be used to detect the gas to be measured.

[0069] Or it can be understood that the basic principle of the optical waveguide sensor is that the waveguide structure at the sensing waveguide structure interacts with the external gas molecules to change the light transmission characteristics. Therefore, during the sensing detection process of the optical waveguide sensor, the reference arm is placed in the air, and the sensing arm is used to introduce the gas to be measured. The concentration of the gas to be measured is calculated by the light field intensity ratio after the interference of the output light on both sides. When the optical waveguide transmitted in the sensing waveguide structure interacts with the gas to be measured, or when it is called coupling, the overall structure of the sensing waveguide structure is an important indicator that affects the coupling loss. By adjusting the structure of the sensing waveguide structure, the detection accuracy of the gas to be measured can be improved.

[0070] Furthermore, the light transmitted to the sensing arm through the first coupler can first pass through the first nonlinear gradient waveguide structure to realize the conversion of the light field mode, for example, from TE0 to TE1 or to TE2, that is, the fundamental mode of the transverse electric mode is converted to the high-order mode of the transverse electric mode, where TE0, TE1 and TE2 represent different modes of the light field. Furthermore, after passing through the first nonlinear gradient waveguide structure, the light is transmitted to the sensing waveguide structure through the first mode spot conversion waveguide structure, and interacts with the gas to be measured at the sensing waveguide structure. The light can adjust the number of light transmission paths and the size of the light spot in the first mode spot conversion waveguide structure, thereby ensuring a better interaction effect between the light and the gas to be measured at the sensing waveguide structure. Furthermore, the sensing arm also includes a second mode spot conversion waveguide structure and a second nonlinear gradient waveguide structure. The second mode spot conversion waveguide structure is used to adjust the light after the light reacts with the gas to be measured back to the number of transmission paths and the size of the light spot when it was originally transmitted to the first mode spot conversion waveguide structure, and then adjust the light field mode of the light back to the original light field mode through the second nonlinear gradient waveguide structure, for example, from TE1 or TE2 to TE0, that is, the high-order mode of the transverse electric mode is converted to the fundamental mode of the transverse electric mode. The first nonlinear gradient waveguide structure and the first mode spot conversion waveguide structure can ensure that the light transmitted to the sensing waveguide structure fully interacts with the gas to be measured, which can also be understood as adjusting the transmission effect of the light through the cooperation of the nonlinear gradient waveguide structure and the mode spot conversion waveguide structure. The light can be adjusted back to the original mode through the second mode spot conversion waveguide structure and the second nonlinear gradient waveguide structure, ensuring that the light emitted by the sensing arm and the light emitted by the reference arm correspond to each other, which is convenient for comparing parameters such as light intensity. Combined with the judgment of the light, the optical waveguide sensor can be used to detect the gas to be measured.

[0071] Furthermore, the waveguide structures arranged adjacent to each other in the sensing arm can be understood as the sensing waveguide structure being the center, the first mode spot conversion waveguide structure and the second mode spot conversion waveguide structure being symmetrically arranged, and the first nonlinear gradient waveguide structure and the second nonlinear gradient waveguide structure being symmetrically arranged. By utilizing the different modes transmitted in the sensing arm and the reference arm, the sensitivity of the optical waveguide sensor can be improved under a limited arm length.

[0072] In summary, the preparation method of the optical waveguide sensor provided in the embodiment of the present invention can effectively improve the detection accuracy of the optical waveguide sensor by adjusting the sensing arm in the interference module, that is, the sensing arm includes a first nonlinear gradient waveguide structure, a first mode spot conversion waveguide structure, a sensing waveguide structure, a second mode spot conversion waveguide structure and a second nonlinear gradient waveguide structure which are arranged adjacent to each other in sequence, and by enriching the structure of the sensing arm.

[0073] Fig. 9 is a flow chart of another method for preparing an optical waveguide sensor provided by an embodiment of the present invention, Fig.10is a diagram of the preparation process of a sensor arm in an optical waveguide sensor provided by an embodiment of the present invention, Fig.11 is a diagram of the preparation process of a sensor arm in another optical waveguide sensor provided by an embodiment of the present invention, Fig.12 FIG. 1 is a diagram showing the preparation process of another sensor arm in an optical waveguide sensor provided by an embodiment of the present invention, with reference to FIG. Figures 9 to 12 As shown, the preparation process of the interference module includes:

[0074] S210 , providing a substrate and a first cladding layer.

[0075] refer to Figure 1 and Figure 2 As shown, the sensing arm 210 of the interference module 200 includes a first nonlinear gradient waveguide structure 211 , a first spot conversion waveguide structure 212 , a sensing waveguide structure 213 , a second spot conversion waveguide structure 214 and a second nonlinear gradient waveguide structure 215 .

[0076] For preparing the first nonlinear gradient waveguide structure 211, the first mode spot conversion waveguide structure 212, the second mode spot conversion waveguide structure 214 and the second nonlinear gradient waveguide structure 215, reference may be made to Fig.10 As shown, when preparing the sensing waveguide structure 213, reference may be made to Fig.11 and Fig.12 shown.

[0077] When preparing the interference module, refer to Fig.10 In step a, Fig.11 Steps a and Fig.12 As shown in step a, a substrate 300 and a first cladding layer 410 on one side of the substrate 300 are prepared.

[0078] S220 , depositing a waveguide structure layer on a side of the first cladding layer away from the substrate.

[0079] For further reference, Fig.10 In step b, Fig.11 Step b and Fig.12 As shown in step b, a waveguide structure layer 2100 is deposited on the side of the first cladding 410 away from the substrate 300, and the waveguide structure layer 2100 is subsequently etched to prepare a first nonlinear gradient waveguide structure 211, a first mode spot conversion waveguide structure 212, a sensing waveguide structure 213, a second mode spot conversion waveguide structure 214 and a second nonlinear gradient waveguide structure 215.

[0080] S230, patterning the waveguide structure layer and preparing a reference arm, a first nonlinear gradient waveguide structure, a first spot conversion waveguide structure, a sensing waveguide structure, a second spot conversion waveguide structure, and a second nonlinear gradient waveguide structure.

[0081] For further reference, Fig.10 As shown in step c, the first nonlinear gradient waveguide structure 211 is prepared by patterning and etching the waveguide structure layer 2100 . Fig.10 The preparation of the first nonlinear gradient waveguide structure is taken as an example for explanation, and the preparation processes of the first mode spot conversion waveguide structure, the second mode spot conversion waveguide structure and the second nonlinear gradient waveguide structure are similar and are not explained one by one by examples.

[0082] refer to Fig.11 Steps c and Fig.12 As shown in step c, the sensing waveguide structure 213 is prepared by patterning and etching the waveguide structure 2100.

[0083] The patterning process can be understood as: coating photoresist on the side of the waveguide structure away from the substrate, and using electron beam exposure. After waiting for development and fixing, inductively coupled plasma etching technology is used to form the final waveguide structure, that is, forming the first nonlinear gradient waveguide structure, the first pattern spot conversion waveguide structure, the sensing waveguide structure, the second pattern spot conversion waveguide structure and the second nonlinear gradient waveguide structure, and finally removing the coated photoresist.

[0084] S240, preparing a second cladding on a side of the waveguide structure away from the first cladding, and the second cladding covers the waveguide structure.

[0085] For further reference, Fig.10 Step d, Fig.11 Steps d and Fig.12 As shown in step d, a second cladding 420 is prepared on the side of the patterned waveguide structure (the first nonlinear gradient waveguide structure, the first spot conversion waveguide structure, the sensing waveguide structure, the second spot conversion waveguide structure, and the second nonlinear gradient waveguide structure) away from the substrate. The second cladding 420 covers the waveguide structure, or it can be understood that the first cladding 410 and the second cladding 420 cover the waveguide structure.

[0086] Optionally, after patterning the waveguide structure layer to prepare the waveguide structure, a silicon dioxide layer of about 2 microns is deposited on the surface of the waveguide structure using plasma enhanced chemical vapor deposition (PECVD) technology, that is, a second cladding is deposited to achieve coating of the waveguide structure.

[0087] S250 , patterning the first cladding layer and the second cladding layer and preparing the first groove and the second groove.

[0088] For further reference, Fig.11 Step e and Fig.12As shown in step e, the first cladding layer 410 and the second cladding layer 420 are etched to form the first groove 411 and the second groove 412 , and at least a portion of the substrate 300 is exposed through the first groove 411 and the second groove 412 .

[0089] The orthographic projection of the sensing waveguide structure 213 onto the substrate 400 at least partially overlaps with the orthographic projection of the first groove 411 onto the substrate 400. Figure 2 , Figure 4 and Figure 5 As shown, the first waveguide 213a and the second waveguide 213b are suspended in the space formed by the first groove 411 and the second groove 421, and are connected to the first mode spot conversion waveguide structure and the second mode spot conversion waveguide structure as the suspended support points of the first waveguide 213a and the second waveguide 213b. This can be understood as the sensing waveguide structure 213 being arranged in the groove region formed by the first cladding 410 and the second cladding 420.

[0090] Optionally, after preparing the second cladding, the photoresist is again spin-coated on the side of the second cladding away from the first cladding and the second cladding is irradiated with an electron beam (irradiating the area where the first groove and the second groove are to be prepared), and after development and fixation, the entire structure is immersed in a hydrofluoric acid (HF) solution. The area not irradiated with the electron beam is protected by the photoresist, that is, the first cladding and the second cladding in the area where the first nonlinear gradient waveguide structure, the first pattern spot conversion waveguide structure, the second pattern spot conversion waveguide structure and the second nonlinear gradient waveguide structure are set are not in contact with HF and are retained; while the second cladding and the first cladding in the area not covered by the photoresist, that is, the sensing waveguide structure, will be corroded by HF, so the first waveguide and the second waveguide form a suspended waveguide, and finally the photoresist is removed.

[0091] In the optical waveguide sensor provided by the embodiment of the present invention, the sensing waveguide structure in the sensing arm is arranged in a groove, that is, the first waveguide and the second waveguide are arranged in the groove, and the groove waveguide structure is used to maximize the cladding evanescent field limitation factor. The concentration of the gas to be measured is analyzed by the interference result with the optical signal in the reference arm, thereby improving the detection accuracy of the gas to be measured.

[0092] After the interference module is prepared, the coupling module is controlled to be connected with the interference module to realize the preparation of the optical waveguide sensor.

[0093] Based on the same inventive concept, an embodiment of the present invention further provides an optical waveguide sensing device, Fig.13 is a schematic diagram of the structure of an optical waveguide sensor device provided by an embodiment of the present invention, such as Fig.13As shown, the optical waveguide sensing device 1 includes the optical waveguide sensor 10 and the laser 20 described in any of the above embodiments, and the laser 20 is connected to the first coupler 210. Therefore, the optical waveguide sensing device 1 provided in the embodiment of the present invention has the corresponding beneficial effects in the above embodiments, which will not be repeated here.

[0094] Based on the same inventive concept, an embodiment of the present invention further provides a detection method for an optical waveguide sensor device. Fig.14 is a flow chart of a detection method of an optical waveguide sensor device provided by an embodiment of the present invention, with reference to Fig.13 and Fig.14 As shown, the preparation method comprises:

[0095] S310, controlling the laser to input light to the first coupler, and inputting the light to the sensing arm and the reference arm through the first output end and the second output end of the first coupler.

[0096] S320, controlling the interaction between the gas to be measured and the light in the sensing waveguide structure.

[0097] S330, calculating a phase difference between the light transmitted from the reference arm to the second coupler and the light transmitted from the sensor to the second coupler.

[0098] S340, determining the concentration of the gas to be measured according to the phase difference.

[0099] Among them, reference Fig.13 As shown, the length of the sensor arm 210 in the interference module 200 is L1, and the length of the reference arm 220 is L2. The laser 20 emits a detection light beam I0 which is divided into two independent light beams after passing through the first coupler 210, namely, the signal light I1 transmitted in the sensor arm 210 and the reference light I2 transmitted in the reference arm 220. The coherent light transmitted by the sensor arm 210 and the gas to be measured and the reference arm 220 converges at the second coupler 220 to interfere. Then, the output light intensity of the output port 220C of the second coupler 220 is I3, and the output light intensity of the output port 220D of the second coupler 220 is I3.

[0100]

[0101] Where: Δφ=(2πn0ΔL) / λ is the phase difference when two coherent lights interfere, ΔL is the length difference between L1 and L2, n0 is the refractive index of the waveguide structure, and λ is the wavelength of the probe light. It can be seen from the above that the energy output spectrum functions of the output port 220C and the output port 220D are complementary and are periodic cosine functions with respect to Δφ.

[0102] When the gas to be measured is distributed on the sensor arm 210, that is, the gas to be measured is distributed in the gap of the slot waveguide of the sensor arm 210 (the gap between the first waveguide 213a and the second waveguide 213b), the gas fully interacts with the light field in the gap, that is, the refractive index on this section of the transmission path changes, resulting in a change in the optical path of the signal light I1 transmitted in the sensor arm 210, thereby changing the phase difference Δφ when the two coherent lights of the reference arm 220 and the sensor arm 210 interfere. And the corresponding phase difference information is reflected in the change of the output light intensity. By only observing the change in the light intensity of the output signal, the change of the optical signal in the sensor arm 210 can be determined, and then the measured parameters of the gas to be measured can be demodulated. Optionally, the measured parameter can be the detection of the concentration of gases such as CO2, NH3, CH4, etc., and the optical waveguide sensor device can be used in many fields such as biomedicine, environmental monitoring, and disaster warning.

[0103] Optionally, the laser outputs a laser with a laser center wavelength of 2334 nm, which is divided into a reference beam transmitted in a reference arm and a sensor beam transmitted in a sensor arm through a first coupler, and then interferes in a second coupler, and then output through an output port of the second coupler. The optical waveguide sensor device may also include a first photodetector and / or a second photodetector, and the first photodetector is connected to an output port (reference Fig.13 220C) coupling, the output port (reference Fig.13 The light beam signal outputted from 220C) is converted into a first electrical signal, and the second photodetector is connected to another output port of the second coupler (reference Fig.13 220D) coupling, the output port (reference Fig.13 The light beam signal outputted by the optical waveguide sensor 220D) is converted into a second electrical signal, and the data acquisition device and the data processor are electrically connected to the first photodetector and the second photodetector. Based on the intensity change of the first electrical signal or the second electrical signal and the Lambert-Beer law, the concentration of the detection gas in the environment can be obtained. Optionally, the optical waveguide sensor device includes a first photodetector and a second photodetector, one of which is used as a data source and the other is used for inspection and calibration.

[0104] Furthermore, the phase change (phase difference Δφ) between the sensing arm and the reference arm can be calculated based on the intensity change of the first electrical signal and / or the second electrical signal (the light intensity difference when there is no gas to be measured and when there is gas to be measured), and the relationship between Δφ and the concentration of the gas to be measured conforms to the Lambert-Beer law and has a definite curve relationship. This ensures that the detection of the gas to be measured by using the optical waveguide sensor device has stability and reliability.

[0105] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An optical waveguide sensor, characterized in that: Including coupling module and interference module; The coupling module comprises a first coupler and a second coupler, and the interference module is located between the first coupler and the second coupler; The interference module includes a sensing arm and a reference arm; The first coupler includes a first output end and a second output end, the first output end is connected to the first end of the sensing arm, and the second output end is connected to the first end of the reference arm; the second coupler includes a first input end and a second input end, the first input end is connected to the second end of the sensing arm, and the second input end is connected to the second end of the reference arm; Wherein, the sensing arm comprises a first nonlinear gradual change waveguide structure, a first mode spot conversion waveguide structure, a sensing waveguide structure, a second mode spot conversion waveguide structure and a second nonlinear gradual change waveguide structure which are arranged adjacent to each other in sequence; the first nonlinear gradual change waveguide structure is close to the first end of the sensing arm, the first mode spot conversion waveguide structure is located on a side of the first nonlinear gradual change waveguide structure away from the first end of the sensing arm, the sensing waveguide structure is located on a side of the first mode spot conversion waveguide structure away from the first nonlinear gradual change waveguide structure, the second mode spot conversion waveguide structure is located on a side of the sensing waveguide structure away from the first mode spot conversion waveguide structure, the second nonlinear gradual change waveguide structure is located on a side of the second mode spot conversion waveguide structure away from the sensing waveguide structure, and the second nonlinear gradual change waveguide structure is close to the second end of the sensing arm.

2. The optical waveguide sensor according to claim 1, characterized in that: The optical waveguide sensor comprises a substrate and a cladding, wherein the cladding comprises a first cladding and a second cladding, wherein the first cladding is located on one side of the substrate, and the second cladding is located on a side of the first cladding away from the substrate; the first cladding comprises a first groove penetrating the first cladding, and the second cladding comprises a second groove penetrating the second cladding, wherein an orthographic projection of the first groove onto the substrate overlaps an orthographic projection of the second groove onto the substrate; Along the thickness direction of the substrate, the reference arm, the first nonlinear gradient waveguide structure, the first mode spot conversion waveguide structure, the second mode spot conversion waveguide structure and the second nonlinear gradient waveguide structure are located between the first cladding and the second cladding; Along the direction from the first coupler to the second coupler, the projection of the sensing waveguide structure at least partially overlaps with the projection of the first spot conversion waveguide structure; the orthographic projection of the sensing waveguide structure onto the substrate at least partially overlaps with the orthographic projection of the first groove onto the substrate; The sensing waveguide structure includes a first waveguide and a second waveguide, wherein the first end of the first waveguide is connected to the first mode spot conversion waveguide structure, and the first end of the second waveguide is connected to the first mode spot conversion waveguide structure; the second end of the first waveguide is connected to the second mode spot conversion waveguide structure, and the second end of the second waveguide is connected to the second non-mode spot conversion waveguide structure.

3. The optical waveguide sensor according to claim 2, characterized in that: The material of the substrate includes silicon oxide, the material of the first waveguide includes silicon, and the material of the second waveguide includes silicon.

4. The waveguide sensor according to claim 2, characterized in that: Along a first direction, a gap between the first waveguide and the second waveguide is d, wherein 0.1 micrometers ≤ d ≤ 0.3 micrometers, and the first direction is perpendicular to a transmission direction of the optical waveguide in the sensing waveguide structure.

5. The optical waveguide sensor according to claim 1, characterized in that: Along the direction from the first coupler to the second coupler, the length of the first nonlinear gradient waveguide structure is L1, the length of the first mode spot conversion waveguide structure is L2, the length of the sensing waveguide structure is L3, the length of the second mode spot conversion waveguide structure is L4, and the length of the second nonlinear gradient waveguide structure is L5; Along a direction perpendicular to the first coupler pointing to the second coupler, the width of the first nonlinear gradient waveguide structure away from the first mode spot conversion waveguide structure is W1, the width of the first nonlinear gradient waveguide structure close to the first mode spot conversion waveguide structure is W2, the width of the first mode spot conversion waveguide structure close to the first nonlinear gradient waveguide structure is W3, the width of the first mode spot conversion waveguide structure close to the sensing waveguide structure is W4, the width of the sensing waveguide structure is W5, the width of the second mode spot conversion waveguide structure close to the sensing waveguide structure is W6, the width of the second mode spot conversion waveguide structure close to the second nonlinear gradient waveguide structure is W7, the width of the second nonlinear gradient waveguide structure close to the second mode spot conversion waveguide structure is W8, and the width of the second nonlinear gradient waveguide structure away from the second mode spot conversion waveguide structure is W9; Among them: 500 microns ≤ L1 ≤ 700 microns, 30 microns ≤ L2 ≤ 70 microns, 100 microns ≤ L3 ≤ 300 microns; 30 microns ≤ L4 ≤ 70 microns, 500 microns ≤ L5 ≤ 700 microns; 0.1 micron≤W1≤0.5 micron, 0.5 micron≤W2≤1.0 micron, 0.5 micron≤W3≤1.0 micron, 1.0 micron≤W4≤1.5 micron, 1.0 micron≤W5≤1.5 micron, 1.0 micron≤W6≤1.5 micron, 0.5 micron≤W7≤1.0 micron, 0.5 micron≤W8≤1.0 micron, 0.1 micron≤W9≤0.5 micron.

6. The optical waveguide sensor according to claim 1, characterized in that: The sensing waveguide structure includes a straight waveguide structure or a curved waveguide structure.

7. A method for preparing an optical waveguide sensor, used for preparing the optical waveguide sensor according to any one of claims 1 to 6, characterized in that: The preparation method comprises: An interference module is prepared, wherein the interference module comprises a sensing arm and a reference arm; the sensing arm comprises a first nonlinear gradient waveguide structure, a pattern spot conversion waveguide structure, a sensing waveguide structure, and a second nonlinear gradient waveguide structure which are arranged adjacent to each other in sequence; the first nonlinear gradient waveguide structure is close to the first end of the sensing arm, the first pattern spot conversion waveguide structure is located on a side of the first nonlinear gradient waveguide structure away from the first end of the sensing arm, the sensing waveguide structure is located on a side of the first pattern spot conversion waveguide structure away from the first nonlinear gradient waveguide structure, the second pattern spot conversion waveguide structure is located on a side of the sensing waveguide structure away from the first pattern spot conversion waveguide structure, the second nonlinear gradient waveguide structure is located on a side of the second pattern spot conversion waveguide structure away from the sensing waveguide structure, and the second nonlinear gradient waveguide structure is close to the second end of the sensing arm; The control coupling module is connected to the interference module; the first coupler includes a first output end and a second output end, the first output end is connected to the first end of the sensor arm, and the second output end is connected to the first end of the reference arm; the second coupler includes a first input end and a second input end, the first input end is connected to the second end of the sensor arm, and the second input end is connected to the second end of the reference arm.

8. The preparation method according to claim 7, characterized in that: The preparation interference module includes: providing a substrate and a first cladding layer; Depositing a waveguide structure layer on a side of the first cladding layer away from the substrate; The waveguide structure layer is patterned and the reference arm, the first nonlinear gradient waveguide structure, the first pattern spot conversion waveguide structure, the sensing waveguide structure, the second pattern spot conversion waveguide structure and the second nonlinear gradient waveguide structure are prepared; the sensing waveguide structure comprises a first waveguide and a second waveguide, the first end of the first waveguide is connected to the first pattern spot conversion waveguide structure, the first end of the second waveguide is connected to the first pattern spot conversion waveguide structure; the second end of the first waveguide is connected to the second pattern spot conversion waveguide structure, and the second end of the second waveguide is connected to the second non-pattern spot conversion waveguide structure; Preparing a second cladding layer on a side of the waveguide structure away from the first cladding layer, and the second cladding layer covers the waveguide structure; The first cladding and the second cladding are patterned and a first groove and a second groove are prepared; wherein the first groove passes through the first cladding, the second groove passes through the second cladding, an orthographic projection of the first groove onto the substrate overlaps with an orthographic projection of the second groove onto the substrate, and an orthographic projection of the sensing waveguide structure onto the substrate at least partially overlaps with an orthographic projection of the first groove onto the substrate.

9. An optical waveguide sensor device, characterized in that: The optical waveguide sensor and laser according to claims 1 to 6 are included, wherein the laser is connected to the input end of the first coupler.

10. A detection method for an optical waveguide sensor device, characterized in that: The optical waveguide sensor device according to claim 9, wherein the detection method comprises: Controlling the laser to input light into the first coupler, and inputting the light into the sensor arm and the reference arm through the first output end and the second output end of the first coupler; Control the gas to be measured to interact with the light in the sensing waveguide structure; calculating a phase difference between the light transmitted from the reference arm to the second coupler and the light transmitted from the sensor to the second coupler; The concentration of the gas to be measured is determined according to the phase difference.

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