Optical waveguide sensor

Abstract

This invention provides an optical waveguide sensor with a simple structure that can be used as an optical biosensor. [Solution] The optical waveguide substrate 10 is configured to include a cladding 200 and an optical waveguide core 300 embedded in the cladding and extending parallel to the upper surface of the support substrate 100, and a shielding body 90 is also provided. The optical waveguide core is provided with a gap 510 that separates the optical waveguide core into an input section 310 on the input side and an output section 330 on the output side, and the shielding body is arranged to be able to move in and out of the gap.

Description

Technical Field

[0001] The present invention relates to an optical waveguide sensor suitable for use as an optical biosensor.

Background Art

[0002] In recent years, as a platform technology for optical waveguide devices, silicon (Si) photonics has attracted attention. The characteristics of Si photonics are the miniaturization and integration of optical devices such as optical waveguides and corresponding modulators and photodetectors by utilizing the manufacturing process of semiconductor devices such as CMOS (Complementary Metal Oxide Semiconductor), and the high productivity by the 200 mm or 300 mm wafer process provided by diverting existing semiconductor manufacturing technologies. In addition, since a Si waveguide having Si as a waveguide core and a silicon oxide film (SiO2) as a cladding has a relative refractive index difference reaching 40%, a high light confinement effect can be obtained. Particularly in a Si wire waveguide, the curvature radius of a bent waveguide and the parallel wiring pitch can be reduced to the order of several microns, enabling miniaturization of an optical circuit layout.

[0003] As an example of various applications of optical waveguide devices, there is an optical waveguide sensor used for optical sensing, and particularly its application to the detection of biomaterials applicable to medical treatment and the like is expected.

[0004] Here, as a method for detecting biomaterials, a method using magnetic beads is expected to have many opportunities for use because it has high sensitivity and can separate the detected substances (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Many detection methods using magnetic beads, including the technology disclosed in Patent Document 1 mentioned above, utilize a spatial light beam.

[0007] However, to miniaturize the device and make it even cheaper, it is best to use an optical waveguide sensor that utilizes an optical waveguide.

[0008] This invention has been made in view of these circumstances. The object of this invention is to provide an optical waveguide sensor with a simple structure that can be used as an optical biosensor. [Means for solving the problem]

[0009] To achieve the above-mentioned objectives, the optical waveguide sensor of this invention comprises an optical waveguide substrate comprising a support substrate, a cladding provided on the support substrate, and an optical waveguide core embedded in the cladding and extending parallel to the upper surface of the support substrate, and a shielding body. The optical waveguide substrate is provided with an opening that exposes a cross-section obtained by cutting the optical waveguide core with a plane perpendicular to the direction of light propagation, and the optical waveguide core is separated into an input section on the input side and an output section on the output side by the opening, and the shielding body is arranged to be able to move in and out of the gap between the input section and the output section.

[0010] According to a preferred embodiment of the optical waveguide sensor of this invention, the shielding body comprises a main body which is a magnetic bead and a receptor located on the surface of the main body, the shielding body is movable in a direction perpendicular to the upper surface of the support substrate, and an antibody is provided at the bottom of the opening.

[0011] According to another preferred embodiment of the optical waveguide sensor of the present invention, the input section has a width on the input side that satisfies the single-mode condition, and its width gradually widens toward the output section, and the output section has a width on the output side that satisfies the single-mode condition, and its width gradually narrows toward the output side.

[0012] According to another preferred embodiment of the optical waveguide sensor of this invention, an auxiliary waveguide connecting the input section and the output section is provided in a region other than the region where the gap is formed.

[0013] Furthermore, according to another preferred embodiment of the optical waveguide sensor of this invention, the optical waveguide substrate is provided with a light source optically connected to the input-side end face of the input section and a light-receiving element optically connected to the output-side end face of the output section.

[0014] Furthermore, according to another preferred embodiment of the optical waveguide sensor of this invention, gratings are formed in the input section and the output section.

[0015] According to another preferred embodiment of the optical waveguide sensor of the present invention, a plurality of pairs of input and output units are provided, and the shielding body is arranged to be able to move in and out of the gap between each pair of input and output units.

[0016] Furthermore, according to another preferred embodiment of the optical waveguide sensor of the present invention, the light source and the light-receiving element are provided on a substrate different from the optical waveguide substrate, the light generated by the light source is input to the input section via the grating, and the light-receiving element receives the light output from the output section via the grating.

[0017] Furthermore, according to another preferred embodiment of the optical waveguide sensor of the present invention, the shielding body comprises a main body which is a metal sphere and a receptor located on the surface of the main body, the shielding body is movable in a direction parallel to the upper surface of the support substrate, an antibody is provided on the side surface of the opening, and the metal sphere is attached to the bottom surface or side surface of the opening via an arm.

[0018] Furthermore, according to another preferred embodiment of the optical waveguide sensor of this invention, two pairs of input and output units are provided. One of the input and output unit pairs is a detection unit in which the shielding body is positioned to move in and out of the gap between the input and output units. The other of the input and output unit pairs is a reference unit that does not have the shielding body that can move in and out of the gap between the input and output units.

[0019] Furthermore, according to a further preferred embodiment of the optical waveguide sensor of this invention, a branched waveguide is provided, and the light input to the optical waveguide sensor is branched into two by the branched waveguide before being input to each of the input units.

[0020] Furthermore, according to another preferred embodiment of the optical waveguide sensor of this invention, there are n (where n is an integer of 2 or more) + 1 pairs of input and output units. One of the n pairs of input and output units is a detection unit in which the shielding body is positioned to move in and out of the gap between the input and output units. The remaining one of the pairs of input and output units is a reference unit that does not have the shielding body that can move in and out of the gap between the input and output units.

[0021] Furthermore, according to a further preferred embodiment of the optical waveguide sensor of this invention, antibodies that react with different detection targets are provided at each of the apertures of the detection unit n.

[0022] Furthermore, according to another preferred embodiment of the optical waveguide sensor of this invention, a branched waveguide is provided, and the light input to the optical waveguide sensor is branched n times by the branched waveguide before being input to each of the input units.

[0023] Furthermore, according to a further preferred embodiment of the optical waveguide sensor of this invention, the optical waveguide sensor comprises a branched waveguide and a multiplexed waveguide, wherein the light input to the optical waveguide sensor is branched n times by wavelength separation in the branched waveguide and then input to each of the input units, and the outputs of each of the detection units and the reference unit are wavelength multiplexed in the multiplexed waveguide.

[0024] According to another preferred embodiment of the optical waveguide sensor of the present invention, a cover that forms a microchannel and covers the opening is provided.

[0025] According to a further preferred embodiment of the optical waveguide sensor of the present invention, n (n is an integer of 2 or more) + 1 pairs of the input part and the output part are provided. The n pairs of the input part and the output part are detection parts where the shielding body is arranged so as to be able to enter and exit the gap between the input part and the output part. The remaining one pair of the input part and the output part is a reference part that does not include the shielding body that can enter and exit the gap between the input part and the output part. Further, antibodies that react with the same detection target are provided at the openings of each of the n detection parts.

Advantages of the Invention

[0026] According to the optical waveguide sensor of the present invention, since the shielding body is provided so as to be able to enter and exit the gap between the input part and the output part of the optical waveguide core separated by the opening, it has a simple structure and can be used as an optical biosensor.

Brief Description of the Drawings

[0027] [Figure 1] It is a schematic diagram for explaining the first sensor. [Figure 2] It is a schematic diagram for explaining the structure of the shielding body and the operation of the first sensor. [Figure 3] It is a schematic diagram for explaining the second sensor. [Figure 4] It is a schematic diagram for explaining the third sensor. [Figure 5] It is a schematic diagram for explaining the fourth sensor. [Figure 6] It is a schematic diagram for explaining the fifth sensor. [Figure 7] It is a schematic diagram for explaining the sixth sensor. [Figure 8] It is a schematic diagram for explaining the seventh sensor. [Figure 9] It is a diagram showing the results of an experiment for confirming the basic operation of the first sensor. [Modes for carrying out the invention]

[0028] The embodiments of this invention will be described below with reference to the figures, but the shapes, sizes, and arrangements of each component are only shown in a general manner to the extent that the invention can be understood. Furthermore, preferred configuration examples of this invention will be described below, but the materials and numerical conditions of each component are merely examples. Therefore, this invention is not limited to the following embodiments, and many changes or modifications can be made to achieve the effects of this invention without departing from the scope of the configuration of this invention. Note that some hatching is applied in the plan view, but this does not indicate a cross-section; it is applied to aid in understanding the invention.

[0029] Furthermore, in this explanation, the direction perpendicular to the upper surface of the cladding is defined as the thickness direction, and the direction perpendicular to both the light propagation direction and the thickness direction is defined as the width direction.

[0030] (Sensor 1) Referring to Figure 1, an example configuration of an optical waveguide sensor (hereinafter also referred to as the first sensor) according to the first embodiment of this invention will be described. Figures 1(A) and (B) are schematic diagrams for illustrating the first sensor. Figure 1(A) is a schematic plan view of the first sensor. Figure 1(B) is a diagram showing the cut end surface of the first sensor cut along line AA.

[0031] The first sensor comprises an optical waveguide substrate 10 and a shielding body 90. The shielding body 90 is positioned to move in and out of the gap 510 that separates the optical waveguide core of the optical waveguide substrate 10.

[0032] First, let me explain the optical waveguide substrate 10.

[0033] The optical waveguide substrate 10 comprises a support substrate 100, a cladding 200, and an optical waveguide core 300. The optical waveguide core 300 is embedded within the cladding 200 and is formed to extend parallel to the upper surface of the support substrate 100. The optical waveguide core 300 and the surrounding cladding 200 form an optical waveguide. As will be described later, the optical waveguide substrate 10 is provided with an opening 500, through which the cross-section of the optical waveguide core 300 is exposed from the cladding 200.

[0034] The optical waveguide substrate 10 can be easily manufactured using standard silicon photonics fabrication methods, for example, by utilizing a commercially available SOI (Silicon On Insulator) substrate. In this case, the support substrate layer of the SOI substrate, which is constructed by sequentially stacking a Si support substrate layer, an SiO2 layer, and a Si layer, becomes the support substrate 100. The SiO2 layer becomes the lower cladding 210.

[0035] The lower cladding 210 should be at least 1 μm thick to prevent light propagating through the optical waveguide from escaping into the support substrate 100. The thickness of the optical waveguide core 300 should preferably be within the range of 200 to 400 nm, which is the value that can achieve single-mode conditions in the depth direction. A thickness of 220 nm is commonly used for the optical waveguide core 300.

[0036] Dry etching or similar processes are performed on the Si layer in regions other than the region that will become the optical waveguide core 300, until the lower cladding 210 is reached. As a result, the Si layer is patterned and the optical waveguide core 300 is formed.

[0037] Subsequently, SiO2 is deposited on the lower cladding 210 by chemical vapor deposition (CVD) or other methods to form the upper cladding 220. The upper cladding 220 is formed to cover the optical waveguide core 300.

[0038] As a result, an optical waveguide core 300 is obtained that is embedded within the cladding 200, which consists of a lower cladding 210 and an upper cladding 220, and extends parallel to the upper surface of the support substrate 100.

[0039] An aperture 500 is formed in the optical waveguide substrate 10 of the first sensor. The aperture 500 is formed, for example, by dry etching. This dry etching is carried out up to the upper surface of the lower cladding 210 or the upper surface of the support substrate 100 in the region where the aperture 500 is formed.

[0040] This aperture 500 separates the optical waveguide core 300 into an input section 310 on the input side and an output section 330 on the output side, sequentially along the longitudinal direction (direction of light propagation).

[0041] When the shielding body 90 fits into the gap between the input section 310 and the output section 330 of the optical waveguide core 300, the light propagating through the optical waveguide is blocked. In this example, in order to maintain the shape of the aperture 500, an auxiliary waveguide 325 is provided in a region other than the area where the gap 510 is formed. The auxiliary waveguide 325 connects the input section 310 and the output section 330 and is provided around the aperture 500. The auxiliary waveguide 325 may also be provided in a portion of the gap between the input section 310 and the output section 330.

[0042] The input section 310 has an inverse taper shape, gradually widening from the input side towards the output section 330. The width on the input side is a width that satisfies the single-mode condition, for example, 440 nm, and the width on the output section 330 side is, for example, 700 nm.

[0043] The output section 330 has a tapered shape, with its width gradually narrowing from the input section 310 side towards the output side. The width of the output side is such that it satisfies the single-mode condition, for example, 440 nm, and the width of the input section 310 side is such that, for example, 700 nm.

[0044] To achieve this, the width of the aperture 500 is made smaller than the width of the optical waveguide core 300, which is 700 nm, and the aperture 500 is positioned so that its center lies on the center line along the longitudinal direction of the optical waveguide core. The size of the aperture 500 is, for example, 400 nm × 400 nm, taking into consideration ease of fabrication. Furthermore, in a configuration like this example, where the optical waveguide core is provided around the aperture 500, not only is the shape of the aperture 500 described above maintained, but the position of the shielding body 90 is also more easily determined.

[0045] The shielding body 90 is movable in a direction perpendicular to the upper surface of the support substrate 100 and is positioned to move in and out of the gap 510 between the input section 310 and the output section 330.

[0046] Although not shown in detail here, the optical waveguide substrate 10 may be provided with a light source such as a laser diode (LD) and a light-receiving element such as a photodiode (PD). The light source is positioned to be optically connected to the input end face of the input section 310 and inputs light to the input section 310. The light-receiving element is positioned to be optically connected to the input end face of the output section 330 and receives light from the output section 330. The light source and light-receiving element may be formed integrally with the optical waveguides of the input section 310 and the output section 330, respectively.

[0047] The structure of the shielding body and the operation of the first sensor will be explained with reference to Figure 2. Figure 2 is a schematic diagram illustrating the structure of the shielding body and the operation of the first sensor. Figures 2(A) and (B), like Figure 1(B), show the cut end face of the first sensor cut along line AA, with an enlarged view of the area around the opening 500. Figure 2(A) shows the state in which the first sensor is not exposed to the sample, and Figure 2(B) shows the state in which the first sensor is exposed to the sample.

[0048] The shielding body 90, which is positioned within the opening 500 so as to be able to move in and out of the gap, is composed of, for example, a main body 91 made of spherical magnetic beads with a diameter of 250 nm and a biomaterial as a receptor 92 modified on its surface.

[0049] Furthermore, antibody 501 is attached to the bottom surface of opening 500.

[0050] When the first sensor is not exposed to the sample, as shown in Figure 2(A), the shielding body 90 is positioned away from the gap 510 of the optical waveguide core 300, that is, in a position that does not obstruct the light propagating through the optical waveguide. The shielding body 90 can be positioned at a desired location by any suitable conventional known method, such as applying a magnetic field with a magnet (not shown).

[0051] When the first sensor was calculated using the 3D BPM (Beam Propagation Method), it was found that when the light propagating through the optical waveguide is not blocked by the shielding body 90, more than 80% of the light input to the first sensor from the input unit 310 is output from the output unit 330. Thus, by employing a tapered structure in the input unit 310 and the output unit 330, the loss of light when the light propagating through the optical waveguide is not blocked by the shielding body 90 can be reduced.

[0052] When the first sensor is exposed to the sample, the antibody 501 captures the target object 505, such as an antigen, and then reacts with the receptor 92, the shield 90 fits into the gap 510, as shown in Figure 2(B), completely blocking the light passing through the gap.

[0053] Furthermore, if the main body 91 of the shielding body 90 is made of magnetic beads, the shielding body 90 coupled to the target object 505 can be extracted using a probe with a local magnetic field.

[0054] Thus, this first sensor allows for a simple structure to be used as a biosensor.

[0055] (Second sensor) Referring to Figure 3, an example configuration of an optical waveguide sensor (hereinafter also referred to as the second sensor) according to the second embodiment of this invention will be described. Figures 3(A) and (B) are schematic diagrams for illustrating the second sensor. Figure 3(A) is a schematic plan view of the second sensor. Figure 3(B) is a diagram showing a partial cut end of the second sensor.

[0056] The second sensor differs from the first sensor in that its input section 312 and output section 332 are configured with gratings formed on the optical waveguide core 302. In the first sensor, light generated by a light source located in the direction of the optical waveguide core's extension is input to the input section, and the light output from the output section is sent to a photodetector located in the direction of the optical waveguide core's extension. In contrast, the second sensor, with its input section 312 and output section 332 equipped with gratings, can receive light from a light source 710, such as a laser diode (LD), located on a surface different from the surface of the optical waveguide core's extension, and receive this light with a photodetector 720, such as a photodiode (PD), located on a surface different from the surface of the optical waveguide core's extension.

[0057] Therefore, in the second sensor, for example, as shown in Figure 3(B), the light source 710 and the photodetector 720 can be provided on a substrate 700 different from the optical waveguide substrate 12. In this case, the relatively expensive light source 710 and photodetector 720 can be left as they are, and only the optical waveguide substrate exposed to the sample can be discarded.

[0058] Furthermore, if we assume that the light source 710 and photodetector 720 are left as they are and only the optical waveguide substrate exposed to the sample is to be discarded, then, as shown in Figure 2(A), it is cost-effective to arrange multiple input and output pairs and shielding bodies 90 near each gap on one substrate, and to provide an array of light sources 710 and photodetectors 720 on another substrate 700.

[0059] In addition, the second sensor may also be configured, similar to the first sensor, to maintain the shape of the aperture 500, by providing an auxiliary waveguide connecting the input and output sections in a region other than the area where a gap is formed around the aperture 500.

[0060] (Third sensor) Referring to Figure 4, an example configuration of an optical waveguide sensor (hereinafter also referred to as the third sensor) according to the third embodiment of this invention will be described. Figures 4(A) and (B) are schematic diagrams for explaining the third sensor. Figures 4(A) and (B) are schematic plan views, similar to Figure 1(A), showing an enlarged view of the area near the opening. Figure 4(A) shows the case where the shielding body is removed from the gap, and Figure 4(B) shows the case where the shielding body is placed inside the gap. In Figures 4(A) and (B), the lower cladding and optical waveguide core are stacked on the support substrate, with the upper cladding removed. In this example, the lower cladding and optical waveguide core are removed from inside the opening, and the top surface of the support substrate becomes the bottom surface of the opening.

[0061] In the third sensor, the shielding body 900 is connected to an arm 920, and the arm 920 is connected to the bottom of the opening 503. In this third sensor, it is assumed that the shielding body 900 moves in a plane parallel to the upper surface of the support substrate 100, so the antibody 505 is attached to the side wall of the opening 503. Also, in the third sensor, since the shielding body 900 is attached to the optical waveguide substrate by the arm 920, the main body of the shielding body 900 does not need to be a magnetic bead and can be made of a metal sphere.

[0062] Furthermore, the arm 920 only needs to be movable in a plane parallel to the upper surface of the support substrate 100 and able to move in and out of the gap 513, and can be constructed using any suitable conventional known technology.

[0063] (Fourth sensor) Referring to Figure 5, an example configuration of an optical waveguide sensor (hereinafter also referred to as the fourth sensor) according to the fourth embodiment of this invention will be described. Figure 5 is a schematic diagram for explaining the fourth sensor and is a schematic plan view of the fourth sensor.

[0064] The fourth sensor is configured with a detection unit 1100 and a reference unit 1200 in parallel. It also has a branched waveguide 1300 on the input side. Light input to the input side of the branched waveguide 1300 is split into two at the branching unit 1310, with one branch being sent to the detection unit 1100 and the other to the reference unit 1200.

[0065] The detection unit 1100 is configured similarly to the first sensor described with reference to Figure 1, so a redundant explanation will be omitted. The reference unit 1200 differs from the detection unit 1100 in that it does not have a shielding body. The optical waveguide core of the reference unit 1200 can be configured similarly to the optical waveguide core of the detection unit 1100. Here, a redundant explanation with respect to the first sensor will be omitted.

[0066] The gap between the input and output sections of the reference section 1200 may be filled with cladding, or, similar to the gap in the detection section 1100, it may be configured to be exposed to the sample.

[0067] The fourth sensor measures the difference between the output from the output waveguide of the detection unit 1100 and the output from the output waveguide of the reference unit 1200. When a shielding material is placed in the gap of the detection unit 1100 and blocks the light, the difference between the output of the detection unit 1100 and the output of the reference unit 1200 increases. This makes it possible to detect the target object.

[0068] According to this fourth sensor, the light is split into two and input to the detection unit 1100 and the reference unit 1200, so the light input conditions are standardized between the detection unit 1100 and the reference unit 1200. As a result, ambiguity in detection results due to differences in input conditions can be eliminated.

[0069] In this description, an example has been given in which the optical waveguide cores of the detection unit 1100 and reference unit 1200 of the fourth sensor are configured in the same way as those of the first sensor, but the invention is not limited to this. The optical waveguide cores of the detection unit 1100 and reference unit 1200 of the fourth sensor may also be configured in the same way as those of the second and third sensors.

[0070] (5th sensor) Referring to Figure 6, an example configuration of an optical waveguide sensor (hereinafter also referred to as the fifth sensor) according to the fifth embodiment of this invention will be described. Figure 6 is a schematic diagram for explaining the fifth sensor and is a schematic plan view of the fifth sensor.

[0071] The fifth sensor is configured with a detection unit 1100 for n (where n is an integer greater than or equal to 2) and a reference unit 1200 in parallel. It also has a branched waveguide on the input side. The light input to the input side of the branched waveguide 1302 is branched n+1 times by the branching unit 1312 and sent to the detection unit and reference unit for n, respectively. Figure 6 shows the case where n is 3.

[0072] Each detection unit and reference unit is configured in the same way as the fourth sensor. In the fifth sensor, the antibodies placed in the openings of the first to nth detection units 1100-1 to n are set to react with different target substances. In this case, it can be determined that a target substance that reacts with the antibody placed in the detection unit where the output from the output unit disappears or decreases is present in the sample. This fifth sensor allows for the simultaneous detection of multiple target substances.

[0073] In this description, an example has been given in which the optical waveguide cores of the detection units 1100-1 to n and the reference unit 1200 of the fifth sensor are configured in the same way as those of the first sensor, but this is not limited to this. The optical waveguide cores of the detection units 1100-1 to n and the reference unit 1200 of the fifth sensor may also be configured in the same way as those of the second and third sensors.

[0074] (Sixth sensor) Referring to Figure 7, an example configuration of an optical waveguide sensor (hereinafter also referred to as the sixth sensor) according to the sixth embodiment of this invention will be described. Figure 7 is a schematic diagram for explaining the sixth sensor and is a schematic plan view of the sixth sensor.

[0075] The sixth sensor differs from the fifth sensor in that the branch section 1314 of the branched waveguide 1304 is a demultiplexer that separates wavelengths, and that it is equipped with a multiplexing waveguide 1404 on the output side.

[0076] In the sixth sensor, the demultiplexer 1314 of the branched waveguide 1304 separates the input light by wavelength. As a result, light of different wavelengths is sent to the first to nth detection units 1100-1 to n and the reference unit 1200.

[0077] Furthermore, the multiplexed waveguide 1404 wavelength-multiplexes the light output from the first to nth detection units 1100-1 to n and the output unit of the reference unit 1200 using the multiplexing unit 1414.

[0078] As a result, the sixth sensor indicates that there is a target substance in the sample that reacts with the antibody provided in the detection unit 1100 corresponding to the wavelength at which the output disappears or decreases.

[0079] In this description, an example has been given in which the optical waveguide cores of the detection units 1100-1~n and reference unit 1200 of the sixth sensor are configured in the same way as those of the first sensor, but this is not limited to this. The optical waveguide cores of the detection units 1100-1~n and reference unit 1200 of the sixth sensor may also be configured in the same way as those of the second and third sensors.

[0080] (Seventh sensor) Referring to Figure 8, an example configuration of an optical waveguide sensor (hereinafter also referred to as the seventh sensor) according to the seventh embodiment of this invention will be described. Figure 8 is a schematic diagram for explaining the seventh sensor and is a schematic plan view of the seventh sensor.

[0081] The seventh sensor is equipped with a cover 800 above the opening 500. This cover 800 forms a microchannel through which the fluid sample passes. In this example, the microchannel is provided parallel to the upper surface of the support substrate 100 and extends in a direction perpendicular to the direction of light propagation.

[0082] According to the seventh sensor, if even one target substance is present in the sample, it will eventually be trapped by the antibody in the opening, enabling highly sensitive detection, such as measurement even when the concentration of the target substance is low.

[0083] This microfluidic structure can be applied to any of the first to sixth sensors. Furthermore, if this microfluidic structure is applied to a sensor with multiple detection units, such as the fifth or sixth sensor, and the same antibody is used in all of the n detection units, the concentration of the target substance can be determined by how many of the n detection units detect the substance.

[0084] (Operation confirmed) Referring to Figure 9, the basic operation verification experiment of the first sensor will be described. Here, the structure of the first sensor described with reference to Figure 1 was created on a chip, and biotin was immobilized on the entire surface of the chip as the object to be detected. In addition, ahidin was attached as the receptor to the surface of a 300 nm diameter magnetic bead, which served as the main body.

[0085] Figures 9(A) and (B) show the results of an experiment to confirm the basic operation of the first sensor. In Figures 9(A) and (B), the horizontal axis represents wavelength (unit: nm), and the vertical axis represents transmittance (unit: dB). Here, transmittance is given by the light intensity output from the output unit relative to the light intensity input to the input unit. Figure 9(A) shows the case where the gap size is 400 nm × 400 nm and the waveguide width near the gap is 700 nm, while Figure 9(B) shows the case where the gap size is 250 nm × 250 nm and the waveguide width near the gap is 700 nm.

[0086] In Figures 9(A) and (B), curve I shows the measurement results without a shielding device, and curve II shows the measurement results with a shielding device.

[0087] As shown in Figure 9(A), a decrease in transmittance of approximately 5 dB was observed when a shielding material was present (II) compared to when there was no shielding material (I). Thus, it was confirmed that the first sensor is capable of detecting the presence or absence of an object to be detected.

[0088] On the other hand, in Figure 9(B), although a decrease in transmittance is observed when there is a shielding material (II) compared to when there is no shielding material (I), the degree of decrease in transmittance is smaller than in Figure 9(A). This is because in Figure 9(B), the size of the gap is 250 nm × 250 nm, which is smaller than in Figure 9(A), so the 300 nm diameter shielding material does not fit completely into the gap. However, comparing Figure 9(A) and Figure 9(B), it can be seen that the light loss in the gap is smaller in Figure 9(B) where the gap size is smaller.

[0089] When the gap size was set to 2 μm × 2 μm, a 10 dB power reduction was obtained due to the presence of the shielding material, but the optical loss in the gap also increased to nearly 25 dB. [Explanation of Symbols]

[0090] 10, 12 Optical waveguide substrate 90, 900 shield 100 Support substrate 200 Clad 210 Lower cladding 220 Upper cladding 300, 302, 303 Optical waveguide cores 310, 312 Input section 320 Sensing Unit 325 Auxiliary Waveguide 330, 332 Output section 500 aperture 510, 513 gap 700 circuit boards 710 Light source 720 light-receiving elements 800 Cover 1100 Detection Unit 1200 Reference section 1300, 1032, 1304 branch waveguides Branching point 1310, 1312, 1314 1400, 1404 Waveguides 1414 Gōhabu

Claims

1. Support substrate and A cladding provided on the support substrate, An optical waveguide core embedded within the cladding and extending parallel to the upper surface of the support substrate and An optical waveguide substrate comprising, shield Equipped with, The optical waveguide substrate is provided with an opening that exposes a cross-section obtained by cutting the optical waveguide core with a plane perpendicular to the direction of light propagation. The optical waveguide core is separated into an input section on the input side and an output section on the output side by the aperture. The shielding body is positioned to be able to move in and out of the gap between the input and output sections. Optical waveguide sensor.

2. The aforementioned shielding body is The main body is a magnetic bead, Receptors located on the surface of the main body and Equipped with, The shielding body is movable in a direction perpendicular to the upper surface of the support substrate, An antibody is provided at the bottom of the aforementioned opening. The optical waveguide sensor according to claim 1.

3. The input section has a width on the input side that satisfies the single-mode condition, and the width gradually widens towards the output section. The output section has an output width that satisfies the single-mode condition, and the width gradually narrows towards the output side. The optical waveguide sensor according to claim 1 or 2.

4. An auxiliary waveguide connecting the input and output sections is provided in a region other than the region where the aforementioned gap is formed. The optical waveguide sensor according to claim 1 or 2.

5. On the optical waveguide substrate, The input end face of the input section is optically connected to a light source, The output end face of the output unit and the light-receiving element are optically connected. The optical waveguide sensor according to claim 1 or 2, comprising:

6. A grating is formed in the input and output sections. The optical waveguide sensor according to claim 1 or 2.

7. Multiple pairs of the aforementioned input and output units are provided, The shielding body is positioned so as to be able to move in and out of the gap between each of the pairs of input and output units. The optical waveguide sensor according to claim 6.

8. The light source and light receiving element are provided on a substrate different from the optical waveguide substrate. The light generated by the aforementioned light source is input to the input unit after passing through the aforementioned grating. The light-receiving element receives light output from the output unit after passing through the grating. The optical waveguide sensor according to claim 6.

9. The aforementioned shielding body is The main body is a metal sphere, Receptors located on the surface of the main body and Equipped with, The shielding body is movable in a direction parallel to the upper surface of the support substrate, Antibodies are provided on the side surface of the opening, The metal ball is attached to the bottom or side of the opening via an arm. The optical waveguide sensor according to claim 1.

10. Two pairs of the aforementioned input and output units are provided. One of the pair of input and output units is a detection unit in which the shielding body is positioned to move in and out of the gap between the input and output units. The other of the pair of input and output units is a reference unit that does not have the shielding body that can move in and out of the gap between the input and output units. The optical waveguide sensor according to claim 1 or 2.

11. Equipped with branched waveguides, The light input to the optical waveguide sensor is split into two by the branched waveguide and then input to the respective input units provided in the detection unit and the reference unit. The optical waveguide sensor according to claim 10.

12. The input and output units are provided in pairs of n (where n is an integer of 2 or more) + 1. n of the pair of input and output units is a detection unit in which the shielding body is positioned so as to be able to move in and out of the gap between the input and output units. The remaining part of the pair of input and output units is a reference unit that does not have the shielding body that can move in and out of the gap between the input and output units. The optical waveguide sensor according to claim 1 or 2.

13. Each opening of the detection unit of n is provided with antibodies that react with different detection targets. The optical waveguide sensor according to claim 12.

14. Equipped with branched waveguides, The light input to the optical waveguide sensor is split into n branches by the branched waveguide and then input to each of the input sections. The optical waveguide sensor according to claim 12.

15. Equipped with branched waveguides and combined waveguides, The light input to the optical waveguide sensor is split into n branches by wavelength separation in the branched waveguide, and then input to each of the input sections. The outputs of each of the detection units and the reference unit are wavelength-multiplexed in the multiplexed waveguide. The optical waveguide sensor according to claim 12.

16. The opening is covered by a cover that constitutes a microchannel. The optical waveguide sensor according to claim 1 or 2.

17. The input and output units are provided in pairs of n (where n is an integer of 2 or more) + 1. n of the pair of input and output units is a detection unit in which the shielding body is positioned so as to be able to move in and out of the gap between the input and output units. The remaining one of the pair of input and output units is a reference unit that does not have the shielding body that can move in and out of the gap between the input and output units. Each opening of the detection unit n is provided with an antibody that reacts with the same target substance. The optical waveguide sensor according to claim 16.

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