Optical-waveguide-type sensor and spectroscopic analysis element

Abstract

This optical-waveguide-type sensor comprises, e.g.: a core that extends in a prescribed direction and guides inspection light; a cladding that has a lower refractive index than the core and surrounds at least a portion of the outer periphery of the core; and a groove portion that is positioned in a first direction relative to the core such that a seepage component of the inspection light guided by the core leaks out, an end surface of the groove portion being positioned further to a second-direction side than an end portion of the core, the second direction being orthogonal to the first direction. In the optical-waveguide-type sensor, the groove portion may have an inspection region in which the distance between the core and a surface positioned on the first-direction side of the core is equal to or less than a threshold value. This makes it possible to provide a novel and improved optical-waveguide-type sensor and a novel and improved spectroscopic analysis element with which it is possible to, e.g., further enhance manufacturing accuracy.

Description

Optical waveguide sensor and spectroscopic element

[0001] The present invention relates to an optical waveguide sensor and a spectroscopic element.

[0002] Conventionally, sensors that measure the components, concentration, etc. of a substance using the attenuated total reflection (ATR) method have been known (see, for example, Patent Document 1). This sensor enables sample inspection by utilizing the light (evanescent light) that slightly seeps out of the prism in contact with the sample when infrared light is totally reflected inside the ATR crystal prism.

[0003] Japanese Patent Application Laid-Open No. 2005-61904

[0004] For this type of sensor, for example, it would be beneficial if the device could be fabricated with greater precision.

[0005] Therefore, one object of the present invention is to provide a new and improved optical waveguide sensor and spectroscopic analysis element that can be manufactured with higher precision, for example.

[0006] The optical waveguide sensor of the present invention includes, for example, a core extending in a predetermined direction and guiding inspection light, a cladding having a lower refractive index than the core and surrounding at least a portion of the outer periphery of the core, and a groove portion positioned in a first direction of the core so that a seepage component of the inspection light guided by the core can leak out, and whose end face is positioned on the second direction side perpendicular to the first direction relative to the end of the core.

[0007] In the optical waveguide sensor, the groove may have an inspection region in which the distance between the core and a surface of the core located on the first direction side is equal to or less than a threshold value.

[0008] In the optical waveguide sensor, the threshold value may be 5 μm.

[0009] In the optical waveguide sensor, the inspection region may extend along the core.

[0010] In the optical waveguide sensor, the groove may be a microfluidic channel that transports a fluid containing a test object.

[0011] In the optical waveguide sensor, the clad may include a first clad located on the second direction side of the core and a second clad stacked on the first clad, and a step may be formed between the first clad and the second clad.

[0012] The optical waveguide sensor may include an optical branching unit that branches the inspection light.

[0013] In the optical waveguide sensor, the optical branching section may be a power splitter, a WDM, a polarizing beam splitter, a variable splitter, or an optical switch.

[0014] In the optical waveguide sensor, the optical branching section may be a polarizing beam splitter that splits the inspection light into a TE polarization component and a TM polarization component, and the groove section may include a first groove section that guides the TE polarization component of light and is located in the first direction of the core, and a second groove section that has the same shape as or is line-symmetrical to the first groove section and is located in the first direction of the core and guides the TM polarization component of light.

[0015] In the optical waveguide sensor, the core may be curved so that a surface through which the inspection light is input and a surface through which the inspection light is output are the same surface.

[0016] The optical waveguide sensor may include a mode filter that removes higher-order mode components from the inspection light.

[0017] In the optical waveguide sensor, the groove may include a first groove located in the first direction of the core, and a second groove located on the opposite side of the core to the first groove.

[0018] In the optical waveguide sensor, the core may include a first core extending in a predetermined direction and guiding a first inspection light, and a second core extending in a predetermined direction on the opposite side of the groove from the first core and guiding a second inspection light.

[0019] In the optical waveguide sensor, a sensitive film may be formed in the inspection region.

[0020] In the optical waveguide sensor, the inspection region may include a curved portion.

[0021] In the optical waveguide sensor, the curved portion may have a tangent whose angle changes by 360 degrees or more.

[0022] In the optical waveguide sensor, the first core is curved so that the surface through which the inspection light is input and the surface through which the inspection light is output are the same first surface, and the second core is curved so that the surface through which the inspection light is input and the surface through which the inspection light is output are the same second surface, and the first surface and the second surface may be opposing surfaces.

[0023] In the optical waveguide sensor, the core and the clad are made of SiO ２ , Si, SiN, InP, GaAs, or GaN.

[0024] The spectroscopic element of the present invention also includes an optical waveguide sensor.

[0025] According to the present invention, for example, it is possible to obtain a new and improved optical waveguide sensor and spectroscopic element that can be fabricated with higher precision.

[0026] FIG. 1 is an exemplary and schematic plan view of an optical waveguide sensor of a first embodiment. FIG. 2 is a cross-sectional view of the optical waveguide sensor of FIG. 1 taken along line II-II. FIG. 3 is an exemplary and schematic plan view of an optical waveguide sensor of a second embodiment. FIG. 4 is an exemplary and schematic plan view of an optical waveguide sensor of a third embodiment. FIG. 5 is an exemplary and schematic plan view of an optical waveguide sensor of a fourth embodiment. FIG. 6 is an exemplary and schematic plan view of an optical waveguide sensor of a fifth embodiment. FIG. 7 is a cross-sectional view of the optical waveguide sensor of FIG. 6 taken along line III-III. FIG. 8 is an exemplary and schematic plan view of an optical waveguide sensor of a sixth embodiment. FIG. 9 is a cross-sectional view of the optical waveguide sensor of FIG. 8 taken along line IV-IV. FIG. 10 is an exemplary and schematic plan view of an optical waveguide sensor of a seventh embodiment. FIG. 11 is a cross-sectional view of the optical waveguide sensor of FIG. 10 taken along line V-V. Fig. 12 is an exemplary and schematic plan view of an optical waveguide sensor of an eighth embodiment. Fig. 13 is a cross-sectional view of the optical waveguide sensor of Fig. 12 taken along line VI-VI. Fig. 14 is an exemplary and schematic plan view of an optical waveguide sensor of a ninth embodiment. Fig. 15 is a cross-sectional view of the optical waveguide sensor of Fig. 14 taken along line VII-VII. Fig. 16 is an exemplary and schematic plan view of an optical waveguide sensor of a tenth embodiment. Fig. 17 is a cross-sectional view of the optical waveguide sensor of Fig. 16 taken along line VIII-VIII. Fig. 18 is an exemplary and schematic plan view of an optical waveguide sensor of an eleventh embodiment.

[0027] Hereinafter, several exemplary embodiments of the present invention will be disclosed. The configurations of the embodiments shown below, as well as the actions and results (effects) brought about by these configurations, are merely examples. The present invention can also be realized by configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) obtained by the configurations.

[0028] The following embodiments have similar configurations. Therefore, according to the configurations of each embodiment, similar actions and effects based on the similar configurations can be obtained. Furthermore, in the following, similar configurations are given similar reference numerals, and duplicated descriptions may be omitted.

[0029] Furthermore, each drawing is a schematic diagram, and the dimensions in the drawing may differ from the actual dimensions. In each drawing, the X direction is represented by an arrow X, the Y direction is represented by an arrow Y, and the Z direction is represented by an arrow Z. The X direction, Y direction, and Z direction intersect with each other and are perpendicular to each other. In this specification, a plan view is a line of sight seen in the opposite direction to the Z direction, and a plan view is a drawing in that plan view.

[0030] First Embodiment FIG. 1 is a plan view of an optical waveguide sensor 10A (10) according to a first embodiment. The optical waveguide sensor 10 has, for example, a flat rectangular parallelepiped shape that is relatively thin in the Z direction. The optical waveguide sensor 10 can be used, for example, as a spectroscopic analysis element for an object to be inspected. Hereinafter, in this specification, the positive Z direction is described as up and the negative Z direction is described as down. However, when the optical waveguide sensor 10 is used in its entirety or in part in an upright position (for example, rotated 90 degrees so that the X or Y direction is up), the up and down positional relationship in the specification may differ from the positional relationship during use.

[0031] The optical waveguide sensor 10 can be configured as, for example, a known planar lightwave circuit (PLC). In this case, the optical waveguide sensor 10 integrally includes a substrate extending across the Z direction and a structure stacked on the substrate in the Z direction. The substrate is a glass substrate or a silicon substrate. The structure on the substrate includes a core 12 and a clad 11 surrounding the outer periphery of the core 12. The clad 11 and the core 12 are made of, for example, SiO ２The cladding 11 is made of a material containing any of Si, SiN, InP, GaAs, and GaN. The cladding 11 has a refractive index lower than that of the core 12. The cladding 11 does not necessarily have to surround the entire circumference of the core 12 as long as it surrounds at least a portion of the outer periphery of the core 12 and has the effect of confining the inspection light that is guided through the core 12 (see, for example, FIG. 7 ).

[0032] In the optical waveguide sensor 10, the core 12 extends in a predetermined direction and guides the inspection light. As the inspection light is transmitted, a leaking component of the inspection light, i.e., evanescent light, is distributed in a portion of the cladding 11 that is close to the core 12. To detect this evanescent light, the relative refractive index difference between the core 12 and the cladding 11 is preferably, for example, 0.2% to 15%. The inspection light may be either single-mode or multi-mode.

[0033] 1 , the optical waveguide sensor 10 extends along an imaginary plane intersecting the Z direction. The inspection light input to the input end of the core 12 is transmitted along the core 12 and output from the output end of the core 12.

[0034] 2 is a cross-sectional view of the optical waveguide sensor 10A of FIG. 1 taken along line II-II. As shown in FIG. 2, the clad 11 includes a lower clad 11a (first clad) laminated on a substrate 14 and an upper clad 11b (second clad) laminated on the lower clad 11a. The lower clad 11a is located below the core 12, and a step (not shown) is formed between the lower clad 11a and the upper clad 11b. The lower clad 11a and the upper clad 11b are made of, for example, the same material and have the same refractive index, but may be made of different materials or may have different refractive indices.

[0035] The optical waveguide sensor 10 includes a groove 13 located on a side of the core 12 (in a first direction, here, the negative Y direction) so that the leaking component of the inspection light guided by the core 12 can leak out. The groove 13 has a bottom (end face) located below the end of the core 12 (in a second direction perpendicular to the first direction, here, the negative Z direction). The groove 13 has an inspection region 13a located approximately in the center and liquid reservoirs 13b located at both ends. The inspection region 13a extends a predetermined length along the core 12, and the distance L1 between the core 12 and the side of the groove 13 (the surface located on the first direction side of the core 12) is set to be equal to or less than a threshold value. The threshold value is, for example, 5 μm, but can be appropriately selected depending on the inspection target. The groove including the inspection region 13a between the liquid reservoirs 13b extends, for example, over the entire section, with the cross-sectional shape shown in FIG. 2, i.e., with a substantially constant width and a substantially constant depth. The groove 13 functions as a microfluidic channel for transporting a fluid containing a test object by injecting the fluid into the reservoir 13b. The fluid may be, for example, a liquid or a gas, but may also be a viscoelastic body, a flexible solid, or the like. When the fluid is a viscoelastic body or a solid, the optical waveguide sensor 10 may be used in an upright position.

[0036] As described above, evanescent light of the inspection light is distributed in the portion of the cladding 11 surrounding the core 12. Here, if the distance L1 between the core 12 and the side surface of the groove 13 is relatively small, for example, 5 μm or less, the evanescent light of the inspection light leaks from the side surface of the groove 13 and is absorbed by the inspection object inside the groove 13. In other words, the mode field of the inspection light extends further inside the groove 13 than the side surface of the groove 13 facing the core 12. That is, the mode field diameter of the inspection light is greater than the distance from the center of the core 12 to the side surface of the groove 13 facing the core 12. In this case, the intensity of the emitted light decreases relative to the intensity of the incident light by the amount of inspection light absorbed by the inspection object. The amount of decrease in the intensity of the emitted light relative to the incident light (loss intensity), i.e., the amount of absorption, varies depending on the inspection object. Therefore, measuring the loss intensity makes it possible to identify the inspection object. In the portion of the groove 13 other than the inspection region 13a, the cladding 11 around the core 12 is thick, so that no leakage of evanescent light occurs.

[0037] Here, we will explain the manufacturing method of the optical waveguide sensor 10. First, glass films that will become the lower cladding and core are formed in that order on the substrate 14. The core layer is then processed into the shape of a waveguide by lithography and etching, and a glass film that will become the upper cladding is formed on top of that. After that, grooves 13 are formed on the sides of the core 12 by lithography and etching.

[0038] As described above, the optical waveguide sensor 10A (10) includes the groove 13 located on the side of the core 12. As a result, in the optical waveguide sensor 10, the distance L1 between the core 12 and the side of the groove 13 can be processed with lithographic precision, thereby enabling further improvement in manufacturing precision.

[0039] In this embodiment, the optical waveguide sensor 10 is provided with a groove 13 that accommodates a fluid containing the test object, and the side surface of the groove 13 serves as a contact surface through which the evanescent light leaks. With this configuration, the test object can be more easily and stably held in a measurable state than in a configuration without the groove 13.

[0040] Second Embodiment Fig. 3 is a plan view of an optical waveguide sensor 10B (10) according to a second embodiment. As shown in Fig. 3, in this embodiment, inspection light input from an input unit 15, which is a light source or an optical fiber, is coupled to a core 12 by a fiber array 16a. The core 12 is branched into cores 12a and 12b by an optical branching unit 17. The inspection light that has been guided through the cores 12a and 12b is then coupled to an output unit 18, which is a detector or an optical fiber, by the fiber array 16b.

[0041] The optical splitter 17 may be any device capable of splitting the inspection light, such as a power splitter, a WDM (wavelength division multiplexing) splitter, a polarized beam splitter, or a variable splitter.

[0042] When the optical branching unit 17 is a power splitter, the splitter distributes the inspection light to the cores 12a and 12b at a set intensity ratio (for example, 1:1).

[0043] When the optical branching unit 17 is a WDM splitter, the WDM splitter distributes the test light to the cores 12 a and 12 b for different wavelength bands, respectively. In this case, the absorption characteristics of the test object for each wavelength band can be tested based on the loss intensity in each of the cores 12 a and 12 b.

[0044] A case where the optical branching unit 17 is a polarizing beam splitter will be described in a third embodiment.

[0045] When the optical branching unit 17 is a variable beam splitter, the variable beam splitter can variably set the intensity ratio of the inspection light to be distributed to the cores 12a and 12b.

[0046] The optical branching unit 17 can be configured as, for example, an optical switch. In this case, the optical branching unit 17 can selectively input the inspection light to either the core 12 a or 12 b in a time-division manner. The optical switch is an example of an optical branching unit.

[0047] In either case, the optical waveguide sensor 10B (10) can reduce the number of light sources by including the optical branching unit 17 compared to a case without the optical branching unit 17. Furthermore, various inspections are possible with a relatively simple configuration.

[0048] The input unit 15 or the output unit 18 may also include a mode filter that removes higher-order mode components from the inspection light. In this case, the inspection accuracy can be further improved by removing higher-order mode components that are not required for the inspection. The mode filter can also be applied to the configurations of the other embodiments. The location of the mode filter is not limited to the input unit 15 or the output unit 18.

[0049] 4 is a plan view of an optical waveguide sensor 10C (10) according to a third embodiment. In the optical waveguide sensor 10C of this embodiment, the optical branching unit 17A is a polarizing beam splitter that splits the inspection light into a transverse electric (TE) polarization component and a transverse magnetic (TM) polarization component. The grooves include a first groove 13A located on the side of the core 12a that guides the TE polarization component of light, and a second groove 13B that has the same shape as the first groove 13A or is linearly symmetrical across the core 12 and is located on the side of the core 12b that guides the TM polarization component of light.

[0050] As in the first embodiment, the first groove 13A and the second groove 13B each have an inspection region 13Aa (13Ba) located approximately in the center and liquid pools 13Ab (13Bb) located at both ends. The inspection regions 13Aa (13Ba) extend a predetermined length along the cores 12a (12b), and the distance between the cores 12a (12b) and their side surfaces is set to be equal to or less than a threshold value.

[0051] When the optical branching unit 17A is a polarizing beam splitter, the polarizing beam splitter splits the inspection light into a TE polarized component and a TM polarized component. In this case, the absorption characteristics of the inspection object for each polarized component can be inspected based on the loss intensity in each of the cores 12a and 12b.

[0052] 5 is a plan view of an optical waveguide sensor 10D (10) according to a fourth embodiment. In the optical waveguide sensor 10D of this embodiment, the cores 12a and 12b are curved so that the surface through which the inspection light is input and the surface through which the inspection light is output are the same. The optical circuit 19 can be selected appropriately depending on the object to be measured, and may be, for example, an optical interferometer.

[0053] According to this embodiment, the input section 15 and the output section 18 can be arranged on the same surface, which may further reduce the effort and cost required to manufacture the optical waveguide sensor 10D.

[0054] [Fifth Embodiment] Fig. 6 is a plan view of an optical waveguide sensor 10E (10) according to a fifth embodiment. Fig. 7 is a cross-sectional view of the optical waveguide sensor taken along line III-III in Fig. 6. As shown in Fig. 7, the groove 13 of the optical waveguide sensor 10E according to this embodiment is in contact with the core 12 in the inspection region 13a.

[0055] According to this embodiment, the core 12 and the groove portion 13 are in contact with each other. As a result, it is possible to maximize the amount of evanescent light of the inspection light that is absorbed by the inspection object, and it is possible to inspect the inspection object with higher accuracy.

[0056] Sixth Embodiment Fig. 8 is a plan view of an optical waveguide sensor 10F (10) according to a sixth embodiment. Fig. 9 is a cross-sectional view of the optical waveguide sensor taken along line IV-IV in Fig. 8. In the optical waveguide sensor 10F of this embodiment, a lid 20 is disposed on the upper clad 11b. The lid 20 has a hole 20a formed therein that corresponds to the liquid reservoir 13b.

[0057] The lid 20 is made of resins such as COP (cycloolefin polymer), PC (polycarbonate), PET, PS (polystyrene), PDMS, SU-8, etc., or a Si wafer, glass material, etc. The lid 20 is fixed onto the upper clad 11b by direct bonding using plasma surface treatment or by curing an adhesive.

[0058] According to this embodiment, it is possible to handle fluid under pressure using the lid 20. Furthermore, the lid 20 can prevent foreign matter from being mixed into the test object during testing, and can also prevent the fluid injected into the groove 13 from spilling.

[0059] Note that a lid may be provided in the first to fifth embodiments described above and the seventh to eleventh embodiments described below, as in this embodiment. In other embodiments, the lid also makes it possible to handle pressurized fluid. Furthermore, the lid can prevent foreign matter from being mixed into the test object during testing, and can also prevent the fluid injected into the groove from spilling.

[0060] 10 is a plan view of a portion of an optical waveguide sensor 10G (10) according to a seventh embodiment. In the optical waveguide sensor 10G of this embodiment, the grooves include a first groove 13A located on a side of the core 12 and a second groove 13B located on a side of the core 12 opposite to the first groove 13A.

[0061] Fig. 11 is a cross-sectional view taken along the line VV of the optical waveguide sensor shown in Fig. 10. As shown in Fig. 11, a distance L21 between the core 12 and the side surface of the inspection region 13Aa of the first groove 13A and a distance L22 between the core 12 and the side surface of the inspection region 13Ba of the second groove 13B may be the same or different. As an example in which the distance L21 and the distance L22 are different, the distance L22 can be set to 1.1 times the distance L21 to adjust the amount of leakage of evanescent light.

[0062] In this embodiment, the optical waveguide sensor 10 is provided with a first groove 13A and a second groove 13B. With this configuration, for example, different test objects can be accommodated in the first groove 13A and the second groove 13B, and the different test objects can be inspected.

[0063] 12 is a plan view of an optical waveguide sensor 10H (10) according to an eighth embodiment. As shown in FIG. 12, in the optical waveguide sensor 10H according to this embodiment, the core includes a first core 12A that extends in a predetermined direction and guides the first inspection light, and a second core 12B that extends in the predetermined direction on the opposite side of the groove 13 from the first core 12A and guides the second inspection light.

[0064] The length of the inspection area 13aa of the groove 13 for the first core 12A and the length of the inspection area 13ab of the groove 13 for the second core 12B may be the same or different.

[0065] 13 is a cross-sectional view of the optical waveguide sensor taken along the line VI-VI in FIG. 12. In this embodiment, the distance L31 between the first core 12A and the side surface of the inspection region 13aa of the groove 13 is smaller than the distance L32 between the second core 12B and the side surface of the inspection region 13ab of the groove 13. Therefore, the amount of evanescent light leaking from the first core 12A is greater than the amount of evanescent light leaking from the second core 12B. In other words, in this embodiment as well, the optical waveguide sensor 10H(10) includes two cores with different amounts of evanescent light leaking from the side surfaces.

[0066] In this embodiment, the optical waveguide sensor 10 includes two cores (first core 12A and second core 12B) with different amounts of evanescent light leaking from the side surface depending on the length of the inspection area and the distance between the core and the side surface. According to this embodiment, by measuring the loss intensity in the two cores with different amounts of evanescent light leaking, it is possible to inspect the inspection object more accurately than when measuring the loss intensity in one core.

[0067] Note that the distance L31 and the distance L32 may be the same. In this case, first and second inspection lights of different wavelength bands are introduced into the first core 12A and the second core 12B, respectively, and the absorption characteristics of the object under inspection for each wavelength band can be inspected based on the loss intensities in the first core 12A and the second core 12B. Also, the distance L31 and the distance L32 may be different. As an example in which the distance L31 and the distance L32 are different, the distance L32 can be set to twice the distance L31 to adjust the amount of leakage of evanescent light.

[0068] Ninth Embodiment Fig. 14 is a plan view of an optical waveguide sensor 10I (10) according to a ninth embodiment. Fig. 15 is a cross-sectional view of the optical waveguide sensor of Fig. 14 taken along line VII-VII. As shown in Fig. 15, in the optical waveguide sensor 10I according to this embodiment, the upper cladding 11b is removed from both side surfaces and the top surface of the first core 12A and the second core 12B, thereby improving detection sensitivity. However, to adjust the amount of leakage of inspection light, a predetermined thickness of the upper cladding 11b may be left on both side surfaces and the top surface of the first core 12A and the second core 12B.

[0069] Furthermore, since the upper surface of groove portion 13 is positioned higher than the upper surfaces of first core 12A and second core 12B, the fluid contained in groove portion 13 can pass above first core 12A and second core 12B, thereby improving convenience when measuring the same test object multiple times.

[0070] [Tenth Embodiment] Fig. 16 is a plan view of an optical waveguide sensor 10J (10) according to a tenth embodiment. Fig. 17 is a cross-sectional view of the optical waveguide sensor taken along line VIII-VIII in Fig. 16. As shown in Fig. 17, in the optical waveguide sensor 10J according to this embodiment, a sensitive film 21 is formed on the side or bottom surface of the groove 13 including the inspection region 13a.

[0071] The sensitive film 21 is a ligand or receptor that adsorbs proteins, and is a film whose refractive index changes depending on the substance to be detected. The sensitive film 21 is formed by flowing a fluid into the groove 13 using a sol-gel method, volatilizing ethanol, and adsorbing it onto the side and bottom surfaces. The sensitive film 21 may also be formed by sputtering.

[0072] In this embodiment, the optical waveguide sensor 10 can improve detection sensitivity by increasing the change in refractive index caused by the sensitive film 21 .

[0073] 18 is a plan view of an optical waveguide sensor 10K (10) according to an eleventh embodiment. As shown in FIG. 18, in the optical waveguide sensor 10K according to this embodiment, the inspection region 13a includes four curved portions 13ac. The curved portions 13ac each have a tangent angle change of 90 degrees, and the sum of these curved portions 13ac results in a tangent angle change of 360 degrees.

[0074] The cores include a first core 12A that extends in a predetermined direction and guides the first inspection light, and a second core 12B that extends in a predetermined direction on the opposite side of the groove 13 from the first core 12A and guides the second inspection light. The first core 12A is curved so that the surface through which the inspection light is input and the surface through which the inspection light is output are the same first surface. Similarly, the second core 12B is curved so that the surface through which the inspection light is input and the surface through which the inspection light is output are the same first surface. The first surface and the second surface are opposing surfaces.

[0075] In this embodiment, the optical waveguide sensor 10 includes the curved portion 13ac in the inspection region 13a, which allows the inspection region 13a to be set long, thereby improving detection sensitivity. Furthermore, the inspection region 13a can be set long by setting the change in angle of the tangent to the curved portion 13ac to be large (e.g., 360 degrees or more). Furthermore, by making the first surface and the second surface opposite each other, the effort and cost required for manufacturing the optical waveguide sensor 10 may be further reduced.

[0076] While the above describes exemplary embodiments of the present invention, the above embodiments are merely examples and are not intended to limit the scope of the invention. The above embodiments can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the specifications of each configuration, shape, and the like (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be appropriately modified and implemented.

[0077] For example, the number of cores or grooves may be three or more. The optical waveguide sensor may also include multiple cores with the same leakage amount. In this case, one of the cores may be used as a reference waveguide for referencing the loss intensity of an object under test whose characteristics are known.

[0078] DESCRIPTION OF SYMBOLS 10, 10A to 10J...Optical waveguide sensor 11...Cladding 11a...Lower cladding 11b...Upper cladding 12, 12A, 12B...Core 12A, 12a...First core 12B, 12b...Second core 13, 13A, 13B...Groove portion 13a, 13Aa, 13Ba, 13aa, 13ab...Inspection area 13ac...Curved portion 13b, 13Ab, 13Bb...Liquid reservoir 14...Substrate 15...Input portion 16, 16a, 16b...Fiber array 17, 17A...Optical branching portion 18...Output portion 19...Optical circuit 20...Cover portion 20a...Hole 21...Sensitive film L1, L21, L22, L31, L32...Distance X...Direction Y...Direction Z...Direction

Claims

1. An optical waveguide sensor comprising: a core extending in a predetermined direction and guiding inspection light; a cladding having a lower refractive index than the core and surrounding at least a portion of the outer periphery of the core; and a groove portion positioned in a first direction of the core so that a seepage component of the inspection light guided by the core can leak out, the groove portion having an end face positioned on the second direction side perpendicular to the first direction relative to the end of the core.

2. The optical waveguide sensor according to claim 1, wherein the groove has an inspection area in which the distance between the core and a surface of the core located on the first direction side is equal to or less than a threshold value.

3. The optical waveguide sensor according to claim 2, wherein the threshold value is 5 μm.

4. The optical waveguide sensor according to claim 2, wherein the inspection region extends along the core.

5. The optical waveguide sensor according to claim 1, wherein the groove is a microfluidic channel for transporting a fluid containing a test substance.

6. An optical waveguide sensor as described in claim 1, wherein the clad includes a first clad located on the second direction side of the core and a second clad laminated on the first clad, and a step is formed between the first clad and the second clad.

7. The optical waveguide sensor according to claim 1, further comprising an optical branching section that branches the inspection light.

8. The optical waveguide sensor according to claim 7, wherein the optical branching section is a power splitter, a WDM, a polarizing beam splitter, a variable splitter, or an optical switch.

9. The optical waveguide sensor according to claim 7, wherein the optical branching section is a polarized beam splitter that splits the inspection light into a TE polarized component and a TM polarized component, and the groove section includes: a first groove section that guides the TE polarized component of light and is located in the first direction of the core; and a second groove section that has the same shape as or is line-symmetrical to the first groove section and is located in the first direction of the core and guides the TM polarized component of light.

10. The optical waveguide sensor according to claim 1, wherein the core is curved so that the surface through which the inspection light is input and the surface through which the inspection light is output are the same surface.

11. The optical waveguide sensor according to claim 1, further comprising a mode filter for removing higher-order mode components from the inspection light.

12. The optical waveguide sensor according to claim 1, wherein the groove portion includes a first groove portion located in the first direction of the core, and a second groove portion located on the opposite side of the core from the first groove portion.

13. The optical waveguide sensor according to claim 1, wherein the cores include: a first core extending in a predetermined direction and guiding a first inspection light; and a second core extending in a predetermined direction on the opposite side of the groove from the first core and guiding a second inspection light.

14. The optical waveguide sensor according to claim 2, wherein a sensitive film is formed in the inspection area.

15. The optical waveguide sensor according to claim 2, wherein the inspection region includes a curved portion.

16. The optical waveguide sensor according to claim 15, wherein the curved portion has a tangent whose angle changes by 360 degrees or more.

17. An optical waveguide sensor as described in claim 13, wherein the first core is curved so that the surface through which the inspection light is input and the surface through which the inspection light is output form the same first surface, the second core is curved so that the surface through which the inspection light is input and the surface through which the inspection light is output form the same second surface, and the first surface and the second surface are opposing surfaces.

18. The core and the clad are made of SiO ２ 2. The optical waveguide sensor according to claim 1, which is made of a material containing any one of Si, SiN, InP, GaAs, and GaN.

19. A spectroscopic analysis element comprising the optical waveguide sensor according to claim 1.

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