JP6320768B2 - Optical element - Google Patents

Description

  The present invention relates to an optical element having wavelength selectivity.

  Patent Documents 1 to 3 below describe optical biosensors using localized plasmon resonance (LSPR), which is a kind of surface plasmon resonance (SPR).

  In these technologies, a metal microstructure is formed on a substrate, and light is emitted to the metal microstructure to generate LSPR.

  The resonance characteristics (for example, resonance angle and reflectance) of light that generates LSPR have a strong correlation with the refractive index in the vicinity of the surface of the metal microstructure. If an adsorbing element (for example, an antibody) is attached in the vicinity of the surface, the refractive index at that portion changes depending on whether or not a minute substance (for example, an antigen) is adsorbed to the adsorbing element. Therefore, by detecting the change in the resonance characteristics with respect to the incident light, it is possible to examine the presence / absence and amount of adsorption of the minute substance.

  On the other hand, the present inventors have proposed an optical element capable of generating LSPR by periodically forming upstanding minute metal walls on a metal film formed on a substrate (Non-Patent Document 1 below). ). In this technique, light is trapped in a U-shaped cavity surrounded by a metal film and a metal wall by coupling between a resonance mode and a cavity mode of LSPR. This technique has the advantage that a sharp dip in the reflection spectrum can be formed.

  As a result of further research, the present inventors have found a novel structure of a wavelength-selective optical element having basic characteristics that can be used as a spectroscopic device, an optical switch, or a biosensor.

International Publication No. 2010/044274 JP 2009-133787 A JP 2010-210253 A

Ya-Lun Ho, Yaerim Lee, Etsuo Maeda, and Jean-Jacques Delaunay, "Coupling of localized surface plasmons to U-shaped cavities for high-sensitivity and miniaturized detectors" Optics Express Vol 21, No. 2, pp1531-1540, 2013 .

  The present invention has been made in view of the above findings. The main object of the present invention is to provide a new wavelength-selective optical element utilizing the SPR or LSPR phenomenon.

  Means for solving the above-described problems can be described as follows.

(Item 1)
A substrate, a plurality of cavities, and a channel,
The substrate is made of an insulator,
The plurality of cavities are disposed on the substrate;
Each of the plurality of cavities includes a first standing part, a second standing part, and a connection part,
The first standing part and the second standing part in each cavity part are both extended outward from the surface of the substrate, and are opposed to each other.
The connection part in each cavity part is disposed on the surface of the substrate, and the cavity part is formed in a substantially U-shaped cross section by connecting the first upright part and the second upright part. It is configured to
The first standing part, the second standing part, and the connection part are all made of a material capable of generating surface plasmon by light irradiation,
The channel portion is disposed between the adjacent cavity portions;
And the said channel part is comprised by the said 1st or 2nd standing part in one of the said adjacent cavity parts, and the said 2nd or 1st standing part in the other of the said adjacent cavity parts. And
Further, the channel section is configured to be able to introduce light from the outside to the substrate surface via the channel section.

(Item 2)
The optical element according to item 1, wherein the light introduced into the substrate surface is confined inside the substrate by coupling between a cavity mode in the cavity portion and a gap mode in the channel portion.

(Item 3)
Furthermore, it has an optical trap detector,
The optical element according to item 1 or 2, wherein the optical trap detection unit is configured to detect presence or absence of an optical trap in the channel unit.

(Item 4)
The optical element according to item 3, wherein the optical trap detection section includes a temperature detection element that detects a temperature change in the channel section.

(Item 5)
The optical element according to item 4, wherein the temperature detection element is configured by a semiconductor disposed between the first upright part and the second upright part in the channel part.

(Item 6)
The optical element according to item 5, wherein the optical trap detection unit is configured to detect the presence or absence of an optical trap in the channel unit by using a resistance change of the semiconductor.

(Item 7)
The number of the cavity portions is at least 3 or more,
And the said cavity part is arrange | positioned periodically with a predetermined pitch. The optical element of any one of the items 1-6.

(Item 8)
Comprising a plurality of optical elements according to any one of items 1 to 7,
The width (w) of the connection portion between the first upright portion and the second upright portion in the cavity portion is set to a different value between the plurality of optical elements. apparatus.

(Item 9)
In addition, it has an angle changer,
The optical element according to item 1 or 2, wherein the angle changing unit is configured to change an incident angle of a light beam on the substrate.

(Item 10)
The angle changing unit includes a piezo element,
The optical element according to item 9, wherein the piezo element is attached to the substrate and adjusts the inclination of the substrate.

(Item 11)
The angle changing unit includes an electrostatic actuator,
Item 10. The optical element according to Item 9, wherein the electrostatic actuator is configured to adjust the inclination of the substrate using electrostatic attraction.

(Item 12)
An optical switching device comprising the optical element according to any one of items 8 to 11.

(Item 13)
Comprising the optical element according to any one of items 1 to 7 and 9 to 11 and an adsorption element;
The adsorption element is configured to adsorb an object in the vicinity of the cavity part or the channel part.
Adsorption sensor.

(Item 14)
A spectroscopic method performed using the spectroscopic device according to item 8,
Irradiating light across the plurality of cavities and the channel; and
Detecting the presence or absence of an optical trap in the channel portion;
Spectroscopic method comprising:

(Item 15)
An optical switching method performed using the optical switching device according to item 12,
Irradiating light across the plurality of cavities and the channel; and
Changing the incident angle;
An optical switching method comprising:

(Item 16)
A substance detection method performed using the adsorption sensor according to item 13,
Irradiating light across the plurality of cavities and the channel; and
Detecting a change in resonance characteristics of the adsorption sensor before and after the object is adsorbed to the adsorption element;
A substance detection method comprising:

  According to the present invention, it is possible to provide a new wavelength-selective optical element using the SPR or LSPR phenomenon. Furthermore, according to the present invention, it is possible to provide a spectroscopic device, an optical switching device, or an adsorption sensor using this optical element.

It is explanatory drawing which shows schematic structure of the spectroscopic device which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing of the optical element used for the spectrometer of FIG. It is a graph which shows an example of the wavelength-absorption characteristic in the optical element of FIG. It is explanatory drawing for demonstrating the optical trap operation | movement in the optical element of FIG. It is explanatory drawing for demonstrating the spectroscopy method using the spectroscopy apparatus of FIG. It is explanatory drawing which shows schematic structure of the optical switching apparatus which concerns on 2nd Embodiment of this invention. FIG. 7 is a partial enlarged explanatory view of the optical switching device of FIG. 6. It is an expanded sectional view of the principal part of the optical element used in the optical switching apparatus of FIG. It is a graph which shows the relationship between the absorption wavelength and incident angle in the optical element of FIG. It is a graph which shows the relationship between the incident angle and the reflectance in the optical element of FIG. It is explanatory drawing which shows the principal part of the adsorption | suction sensor which concerns on 3rd Embodiment of this invention. It is explanatory drawing for demonstrating the manufacturing method of the optical element which concerns on 4th Embodiment of this invention. It is explanatory drawing which shows schematic structure of the optical switching apparatus which concerns on 5th Embodiment of this invention.

(First embodiment: spectroscopic device)
Hereinafter, a spectroscopic device according to a first embodiment of the present invention will be described with reference to the accompanying drawings.

(Configuration of the first embodiment)
The spectroscopic device of the present embodiment includes a plurality of optical elements 101, 102,. Here, n in the code indicates the n-th optical element. Note that the number of optical elements corresponds to the number of wavelengths to be measured (that is, wavelengths λ1, λ2,..., Λn), so that only one wavelength may be detected. Further, the optical elements 101 in the present embodiment are supported by the support 10.

  The spectroscopic device of the present embodiment further includes an optical system 200 for sending light from the sample to the optical elements 101 to 10n, and a table 300 that supports the sample.

(Optical element)
Taking one optical element 101 as an example, the configuration of the optical element will be described in detail with further reference to FIG. The configuration of the other optical elements 102 is basically the same as that of the optical element 101. Note that FIG. 2 is shown upside down with respect to FIG.

  The optical element 101 includes a substrate 11, a plurality of cavity portions 121, 122,..., 12 n, a channel portion 13, and an optical trap detection portion 14.

The substrate 11 is made of an insulator. In this embodiment, the insulator is preferably made of a material that can transmit light used as probe light. Such a material, for example sapphire, quartz _glass, is a _{CaF 2, Si 3 N 4,} Al 2 O 3, other materials may be used.

  The plurality of cavity portions 121, 122,..., 12n are arranged on the surface of the substrate 11 (upper surface in FIG. 2). In addition, although the several cavity parts 121,122, ..., 12n in this embodiment are periodically arrange | positioned in the left-right direction in FIG. 2, it demonstrates mainly the adjacent cavity parts 121 and 122 in the following description. To do. The minimum number of the cavity portions is theoretically two, but is practically preferably three or more.

  The cavity part 121 includes a first upright part 1211, a second upright part 1212, and a connection part 1213.

  The first upright portion 1211 and the second upright portion 1222 in the cavity portion 121 both extend outward from the surface of the substrate 11 (upward in FIG. 2) and are opposed to each other. More specifically, the first upright portion 1211 and the second upright portion 1222 in this example are parallel to each other, and both are in the depth direction (direction intersecting the paper surface of FIG. 2, FIG. 5 described later). See).

  The connection part 1213 in the cavity part 121 is disposed on the surface of the substrate 11 and connects the first upright part 1211 and the second upright part 1212. The connecting portion 1213 is also extended in the depth direction. With this configuration, the connection portion 1213 is configured to form the cavity portion 121 in a substantially U-shaped cross section (see FIG. 2).

The first upright portion 1211, the second upright portion 1212, and the connecting portion 1213 in the present embodiment are all made of a material that can generate surface plasmons by light irradiation. Such a material is, for example, gold, but other materials such as silver, platinum, alloys thereof, and oxide semiconductors (for example, VO ₂ , In ₂ O ₃ ) can be used. Note that an oxide semiconductor that is not strictly a metal can be used as long as it can generate surface plasmons.

  Similarly, the cavity part 122 includes a first upright part 1221, a second upright part 1222, and a connection part 1223. The configuration of the cavity part 122 is basically the same as that of the cavity part 121. The same applies when other cavities exist. As will be described later, the width w of the cavity portion (see FIG. 2A) is set corresponding to the wavelength to be detected. Specifically, the width of the cavity portion is set to a different value between the plurality of optical elements 101,..., 10n, so that different wavelengths (λ1,..., Λn) can be detected. It has become.

  In FIG. 2, the central channel portion 13 is disposed between the adjacent cavity portion 121 and the cavity portion 122. Similarly, the other channel part 13 is arrange | positioned between adjacent cavity parts. For this reason, in this embodiment, the several channel part is arrange | positioned periodically.

  In FIG. 2, the center channel portion 13 is constituted by a second upright portion 1212 in the cavity portion 121 and a first upright portion 1221 in the adjacent cavity portion 122. That is, more generally, the channel portion 13 includes a first or second upright portion in one of the adjacent cavity portions, and a second or first upright portion in the other of the adjacent cavity portions. It is constituted by. In short, the channel portion 13 is a gap formed between adjacent channel portions.

  Furthermore, each channel part 13 can introduce light from the outside into the surface of the substrate 11 through this channel part. That is, at the bottom of each channel portion 13, there is no light reflecting layer (for example, a metal layer), and light from the outside can reach the substrate 11.

The optical trap detection unit 14 is configured to detect the presence or absence of an optical trap in each channel unit 13. More specifically, the optical trap detection unit 14 includes temperature detection elements disposed in the respective channel units 13. In the optical trap detection unit 14 of the present embodiment, a semiconductor is used as a temperature detection element, and the presence or absence of an optical trap in each optical trap unit is detected using a change in resistance of the semiconductor. FIG. 2B shows an equivalent circuit of the cavity 121,... Sandwiching a semiconductor as a temperature detecting element. Since each semiconductor is connected in series via the cavity, the overall resistance is approximately N × R (T).
Can be expressed as here,
N: the number of channel portions (that is, the number of semiconductors),
R: resistance value of the semiconductor part,
T: The temperature of the semiconductor portion. In the above formula, it is assumed that the conductivity of the cavity is sufficiently higher than that of the semiconductor in order to improve the SN ratio, but it is possible to reduce the conductivity of the cavity to some extent.

  The resistance R of the semiconductor is a function of the temperature T and changes sensitively according to the temperature. As will be described later, when an optical trap occurs in the channel section 13, the semiconductor temperature rises. Therefore, the presence or absence of the optical trap in the optical element can be detected by detecting the entire resistance value.

(Optical system)
The optical system 200 (see FIG. 1) is a so-called collimating optical system that converts the light from the sample into parallel light and sends it to the optical elements 101 to 10n.

(table)
The table 300 (see FIG. 1) is configured to be able to move the sample in the XY direction.

(Spectroscopic method)
Next, a spectroscopic method using the spectroscopic device will be described.

(Basic characteristics of optical elements)
As a premise for explanation, an example of basic characteristics of the optical element of the present embodiment will be described with reference to FIG.

  In this optical element, the absorption wavelength of light changes corresponding to the width w of the cavity portions 121. In the example of FIG. 3, every time the width w changes by 25 nm, the absorption wavelength changes by approximately 50 nm. Therefore, a plurality of wavelengths can be detected by changing the width w for each optical element. In addition, the example of FIG. 3 was calculated | required by simulation, The conditions are as follows.

(Simulation conditions of FIG. 3)
Cavity placement period d = 1.780-1.905 μm
(Cavity width w = 1.150-1.275μm)
Cavity height h = 1.1μm
Each channel width (semiconductor width) = 0.23μm
Thickness t (silver layer) of metal layer composing the cavity = 0.2μm
Incident angle = 0 deg
Board material: Si ₃ N ₄
P-polarized light of incident light: direction parallel to the paper surface of FIG.

In the optical element of the present embodiment, the light irradiated toward the substrate 11 from above in FIG. 4 is trapped by the channel portion 13 and enters the substrate 11, and vortices are generated inside the substrate 11. Wrap (ie “contained”). This trap is considered to be generated by coupling between a cavity mode in the cavity portion and a gap mode in the channel portion. More specifically, this trap
This is considered to be caused by (1) the coupling between the LSPR and the cavity mode at the end of each standing part, and (2) the coupling between the coupling in (1) and the gap mode in the channel part. The couplings (1) and (2) are caused by light having a very narrow wavelength (see FIG. 3).

  Therefore, by detecting the presence (that is, electromagnetic change) of the light trapped in the channel portion, the occurrence of an optical trap at a specific wavelength can be detected.

(Light irradiation step)
Even in the spectroscopic method of this embodiment, the basic method can be the same as that of a conventional spectroscopic device. For example, probe light (for example, infrared light) is irradiated toward the sample. Then, light reflected by the sample or transmitted through the sample is irradiated to the optical elements 101 to 101 n of the present embodiment via the optical system 200. Thereby, light can be irradiated over several optical trap parts and connection parts in each optical element. Here, the sample is, for example, a part of a living tissue. As is well known, the absorption wavelength of light changes between normal cells and abnormal cells (for example, cancer cells). Therefore, the presence or absence of abnormal cells can be detected by detecting the absorption wavelength. Note that the sample is not limited to a living tissue, and may be other organic materials or inorganic materials that require measurement of an absorbance spectrum.

(Optical trap detection step)
Subsequently, the presence or absence of the optical trap in the optical trap part of the optical elements 101 to 10n is detected for each specific position in the XY plane. This detection is possible by measuring the resistance value R (T). By detecting the presence or absence of an optical trap for each of the optical elements 101 to 10n, it is possible to detect for each wavelength whether or not absorption of a wavelength specific to the optical element occurs. For example, if the absorption wavelength peculiar to the O—H group is λ1, the presence / absence and amount of the O—H group can be detected by detecting an optical trap in an optical element corresponding to this λ1. Similarly, if optical elements corresponding to other absorption wavelengths λ2,..., Λn are provided, substances corresponding to the respective wavelengths can be detected (see FIG. 5).

  Further, the light irradiation is performed while driving the table 300 while shifting the relative positional relationship between the sample and the optical element. Thereby, the test | inspection of the sample for every place in an XY plane can be performed. For example, in this example, an absorbance spectrum represented by a set of (λ1, λ2,..., Λn) can be obtained for each (x, y) coordinate.

  In the present embodiment, since the composition of the sample can be detected without labeling, there is an advantage that the influence on the sample by the label can be prevented and the time required for analysis can be shortened.

  Moreover, in the conventional spectrometer, it was necessary to disperse | distribute light for every wavelength, for example using a diffraction grating. For this reason, not only the whole apparatus becomes large, but also a waveguide for carrying light to the diffraction grating is required. On the other hand, the present embodiment has an advantage that light can be detected for each wavelength only by providing a plurality of optical elements without using a light dispersion means such as a diffraction grating. Further, in this embodiment, since the absorbance spectrum can be obtained by a small optical element, for example, the optical element of this embodiment is attached to the tip of the probe, and an electrical signal (for example, change in voltage or current due to change in resistance value) ) Can be sent to the system side. Then, the whole apparatus can be reduced in size and simplified. Furthermore, it is considered that the absorption spectrum measurement with a low degree of invasiveness to the living body can be performed by putting the optical element in the capsule and sending it into the living body.

  Furthermore, as shown in FIG. 3, the optical element of the present embodiment has a very sharp peak in the absorption characteristic, so that there is an advantage that high measurement accuracy can be obtained. For example, in the above-described technique of Non-Patent Document 1, 42 nm is obtained at a wavelength of 2 μm as a full width at half maximum (FWHM). This characteristic itself can be said to be a fairly sharp peak. However, according to the optical element of this embodiment, as illustrated in FIG. 3, a narrow FWHM of 7 to 24 nm can be obtained at a wavelength of about 2 times, ie, around 4 μm. Therefore, by using the optical element of the present embodiment, a spectroscopic device having high measurement accuracy can be provided.

(Second embodiment: optical switch)
Next, an optical switching device according to a second embodiment of the present invention will be described with reference to FIGS. In the description of the second embodiment, the same reference numerals are used for elements that are basically the same as those in the first embodiment, thereby avoiding complicated description.

Also in the optical switching device of the second embodiment, a plurality of optical elements 101, 102,..., 10n are used (see FIG. 6). An enlarged view of the optical element 101 is shown in FIG. However, in the optical element of this embodiment, the optical trap detector 14 in the first embodiment is omitted, and air as an insulator exists in each channel portion 13 (see FIG. 8). Note that other insulators such as quartz glass, Si ₃ N ₄ , and sapphire can be used instead of air. Each optical element of the second embodiment has a cantilever structure in which one end is fixed and the other end is a free end (see FIG. 7).

  Furthermore, the optical switching device according to the second embodiment includes an angle changing unit 15 (see FIG. 7), a light receiving unit 16, and a beam splitter 17.

  The angle changing unit 15 (see FIG. 7) has a function of changing the inclination angle of each optical element 101... (That is, the light incident angle on each optical element) (in FIG. 6, the angle changing unit is illustrated. Omitted). Such an angle changing unit 15 can be configured using, for example, a piezo element that is attached to the substrate 11 supported in a cantilever manner and deforms the substrate 11 by its own deformation. That is, the piezo element constituting the angle changing unit 15 is attached to the substrate 11 to adjust the inclination angle θ (see FIG. 7) of the substrate 11. In addition, with this configuration, the angle changing unit 15 can change the incident angle of the light beam on the substrate 11. However, the angle changing unit 15 is not limited to a piezo element, and may be constituted by, for example, an electrostatic actuator. If an electrostatic actuator is used, the tilt angle of the substrate can be adjusted using electrostatic attraction.

  The light receiving unit 16 receives light reflected by each optical element, and can transmit the received light through, for example, an optical fiber (not shown) (see FIG. 6).

  The beam splitter 17 reflects infrared light from a light emitting element (for example, a laser diode) 18 with a predetermined reflectance and sends it to a corresponding optical element so that the transmitted light reaches a subsequent beam splitter. (See FIG. 6). In the illustrated example, the reflectivity of the beam splitter 17 is set to increase sequentially from left to right, such as 1/5, 1/4, 1/3, and 1/2.

(Operation of Second Embodiment)
Next, the operation of the optical switching device according to this embodiment will be described.

(Characteristics of optical elements)
The optical element of the second embodiment also has the sharp wavelength selectivity characteristic described in the first embodiment. However, in the second embodiment, another characteristic of the optical element is used. This characteristic will be described with reference to FIG.

In this optical element, there is a relationship as shown in FIG. 9 between the occurrence of mode coupling and the incident angle. For example, it is assumed that mode coupling occurs at the wavelength λa when the incident angle θ = 0 °, and absorption of a waveform as shown in FIG. 3 (that is, a decrease in reflectance) occurs. At this time, when the incident angle θ is changed, as shown in FIG. 9, the wavelength of the resonating light changes. FIG. 9 shows the conditions of the wavelength and angle at which the reflectance is minimum (R _minimum = 0.2), and the reflectance is approximately 0.8 at points outside this graph. Although not clearly shown in FIG. 9, for example, when the incident angle changes by 2 degrees, the resonance wavelength changes by 20 to 30 nm. This relationship can be expressed as an incident angle and a reflectance difference when the wavelength is λb (see FIG. 9), as shown in FIG. With only a 2 degree change in the incident angle, the reflectivity changes greatly from about 0.2 to 0.8. Therefore, it can be seen that optical switching can be performed by changing the incident angle. Here, the characteristics shown in FIG. 10 are obtained by simulation, and the simulation conditions are as follows.

(Simulation conditions in FIG. 10)
Arrangement period of cavity part d = 1.50μm
Cavity height h = 0.77μm
Width of each channel part (air layer) = 0.11μm
Thickness (silver layer) of metal layer composing the cavity part = 0.1μm
Incident angle = 0-5 deg
Board material: Si ₃ N ₄
P-polarized light of incident light: direction parallel to the paper surface of FIG.

  The characteristics described for the optical element of the first embodiment also have the characteristics of the optical element of the second embodiment. The characteristics described in the second embodiment can also be exhibited by the optical element of the first embodiment.

(Optical switching method)
Based on the characteristics of the optical element described above, the optical switching method in this embodiment will be described.

  First, as a premise, it is assumed that light of a specific wavelength (for example, 1.55 μm) is emitted from the light emitting element 18 to the beam splitter 17 (see FIG. 6). Thereby, light can be irradiated over several optical trap parts and connection parts in each optical element.

  Furthermore, in this embodiment, the inclination angle θ of the substrate 11 is changed using the angle changing unit 15 (see FIG. 7). However, the inclination angle θ is set to be very small (for example, about 1 to 5 degrees).

  Then, the light transmitted to the optical element by the beam splitter 17 is reflected by the surface of the optical element and reaches the light receiving unit 16 through the beam splitter 17. The arrived light is transmitted through a transmission medium such as an optical fiber.

  Here, in this embodiment, since the fluctuation range of the tilt angle of the substrate 11 is set to a small value (for example, 1 to 5 degrees), the light reflected by the optical element can be received by the light receiving unit 16 without any problem. (See FIG. 6).

  In the present embodiment, as shown in FIGS. 9 and 10, the reflectance (or absorption rate) varies greatly depending on the change in the incident angle of light. For this reason, the amount of received light (the intensity of received light) in the light receiving unit 16 can be switched by the change in the inclination angle of the substrate 11 (that is, the change in the incident angle). Thereby, there exists an advantage that optical switching can be performed without performing photoelectric conversion.

  Furthermore, in this embodiment, since the substrate 11 has a cantilever structure, if the substrate 11 is reduced in size, it can be vibrated at high speed (for example, in the order of several kHz to several GHz). For this reason, there is an advantage that high-speed optical switching can be realized.

  Further, in the present embodiment, there is an advantage that the frequency of light to be switched can be set to a different value for each optical element by making the width w of the cavity portion in each optical element different.

  Other configurations and advantages of the second embodiment are the same as those of the first embodiment, and thus detailed description thereof is omitted.

(Third embodiment ... Adsorption sensor)
Next, an adsorption sensor according to a third embodiment of the present invention will be described with reference to FIG. In the description of the third embodiment, elements that are basically the same as those in the first embodiment described above are denoted by the same reference numerals, thereby avoiding complicated description.

  In the adsorption sensor of the third embodiment, one optical element 101 is used (see FIG. 11).

  Further, the suction sensor of this embodiment includes a suction element 19. The adsorbing element 19 is configured to adsorb an object in the vicinity of each connection part 1213, 1223,... Of the cavity parts 121, 122,. Furthermore, the adsorption element 19 of the present embodiment is also disposed inside the channel portion 13 (side surface of the standing portion). More specifically, in the present embodiment, a ligand that adsorbs to a specific object (analyte) is used as the adsorbing element, and the end of this ligand is connected to each connecting portion 1213... And the channel portion 13. Bound to the surface.

(Substance detection method in the third embodiment)
Next, the operation of the adsorption sensor according to this embodiment will be described.

  A solution containing an object is allowed to flow so as to come into contact with the surface of the adsorption sensor of the present embodiment. Then, a part of the object is sucked and held by the suction element 19.

  On the other hand, light is irradiated over the plurality of cavity portions 121, 122,..., 12n and the channel portion 13 in the optical element.

  Next, a change in the resonance characteristics of the optical element before and after the object is adsorbed by the adsorption element 19 is detected. That is, when the object is adsorbed by the adsorption element 19, the vicinity of the cavity and / or the inside of the channel part The refractive index changes, and the resonance condition for causing optical confinement in the substrate 11 changes. For example, the wavelength and incident angle of the resonating light change. Therefore, the object can be detected by detecting this change. Therefore, this adsorption sensor can be used as a so-called bio-chemical sensor, for example. Since the detection method itself using this change in resonance condition is the same as that of a conventional chemical sensor using SPR (see, for example, Patent Document 1 described above), further detailed description is omitted.

  Other configurations and advantages of the third embodiment are the same as those of the first embodiment, and a detailed description thereof will be omitted.

(Fourth embodiment: manufacturing method)
Next, as a fourth embodiment, an example of a method for producing the optical element of the present invention will be described with reference to FIG. In the description of the fourth embodiment, elements that are basically the same as those in the first embodiment described above are denoted by the same reference numerals, thereby avoiding complicated description.

  As shown in FIG. 12A, first, a resist 400 is periodically arranged on the surface of the substrate 11.

  Next, an amorphous silicon layer 500 is formed so as to cover the substrate 11 and the resist 400 (see FIG. 12B). This formation can be performed by sputtering, for example.

  Next, the portion of the amorphous silicon layer 500 arranged in parallel with the substrate 11 is removed by ion beam irradiation from above, and only the portion perpendicular to the substrate 11 is left (see FIG. 12C).

  Next, the resist 400 is removed by plasma etching (see FIG. 12D). Thereby, only the amorphous silicon layer 500 extending in the direction perpendicular to the substrate 11 can be left on the substrate.

  Next, a metal layer 600 is formed over the upper surface of the substrate 11 and the amorphous silicon layer 500 (see FIG. 12E). Sputtering can also be used for this formation.

  Next, the metal layer 600 above the amorphous silicon layer 500 is removed using an ion beam (see FIG. 12F). The remaining metal layer 600 forms the cavity portions 121, 122,... In the above-described embodiment.

  Thereby, the optical element of the structure in 1st Embodiment can be obtained. Note that the amorphous silicon layer 500 (see FIG. 12F) remaining between the metal layers 600 corresponds to the optical trap detection unit 14 in the first embodiment.

(Fifth Embodiment: Modification of Optical Switch)
Next, an optical switching device according to a fifth embodiment of the present invention will be described with reference to FIG. In the description of the fifth embodiment, the same reference numerals are used for elements that are basically the same as those of the second embodiment described above, thereby avoiding complicated description.

  Also in the optical switching device of the fifth embodiment, a plurality of optical elements 101, 102,..., 10n are used (see FIG. 13). Furthermore, the optical switching device of the fifth embodiment uses an angle changing unit 15 (see FIG. 7), a light receiving unit 16, and a beam splitter 17, as in the example of FIG.

  However, in the fifth embodiment, a set of beam splitters 17a and 17b is used in place of one beam splitter 17 (see FIG. 13). In this example, a part of the light from the light emitting element 18 is reflected by the beam splitter 17a and further reflected by the beam splitter 17b and reaches each optical element 101,. A part of the light reflected by each of the optical elements 101,... Passes through the beam splitter 17 b and reaches the light receiving unit 16. In the illustrated example, the reflectivity of the beam splitter 17a is set to increase sequentially from left to right, such as 1/4, 1/3, 1/2, and 1/1. The reflectivity of the beam splitter 17b may be 1/2.

  In the fifth embodiment, since there is no light returning to the light source direction, there is an advantage that energy efficiency can be improved. In addition, it is possible to make the intensity of light reaching each light receiving unit substantially constant.

  Other configurations and advantages of the fifth embodiment are the same as those of the second embodiment, and a detailed description thereof will be omitted.

  The contents of the present invention are not limited to the above embodiments. In the present invention, various modifications can be made to the specific configuration within the scope of the claims.

DESCRIPTION OF SYMBOLS 10 Support body 101,102, ..., 10n Optical element 11 Board | substrate 121,122, ..., 12n Cavity part 1211 * 1221 1st standing part 1212 * 1222 2nd standing part 1213,1223 Connection part 13 Channel part 14 Optical trap detection part DESCRIPTION OF SYMBOLS 15 Angle change part 16 Light-receiving part 17 Beam splitter 18 Light emitting element 19 Adsorption element 200 Optical system 300 Table 400 Resist 500 Amorphous silicon layer 600 Metal layer w Cavity part width d Cavity part arrangement period

Claims (16)

A substrate, a plurality of cavities, and a channel,
The substrate is made of an insulator,
The plurality of cavities are disposed on the substrate;
Each of the plurality of cavities includes a first standing part, a second standing part, and a connection part,
The first standing part and the second standing part in each cavity part are both extended outward from the surface of the substrate, and are opposed to each other.
The connection part in each cavity part is disposed on the surface of the substrate, and the cavity part is formed in a substantially U-shaped cross section by connecting the first upright part and the second upright part. It is configured to
The first standing part, the second standing part, and the connection part are all made of a material capable of generating surface plasmon by light irradiation,
The channel portion is disposed between the adjacent cavity portions;
And the said channel part is comprised by the said 1st or 2nd standing part in one of the said adjacent cavity parts, and the said 2nd or 1st standing part in the other of the said adjacent cavity parts. And
Furthermore, the channel part can introduce light from the outside to the substrate surface via the channel part ,
Absorption having a peak at a wavelength determined by mode coupling generated between a cavity mode in the cavity portion and a gap mode in the channel portion with respect to the light introduced to the substrate surface through the channel portion. An optical element having characteristics . 2. The optical element according to claim 1, wherein the light introduced into the substrate surface is confined inside the substrate by mode coupling between a cavity mode in the cavity portion and a gap mode in the channel portion. . Furthermore, it has an optical trap detector,
The optical element according to claim 1, wherein the optical trap detection unit is configured to detect the presence or absence of an optical trap in the channel unit. The optical element according to claim 3, wherein the optical trap detection section includes a temperature detection element that detects a temperature change in the channel section. The optical element according to claim 4, wherein the temperature detection element is configured by a semiconductor disposed between the first upright part and the second upright part in the channel part. The optical element according to claim 5, wherein the optical trap detection unit is configured to detect the presence or absence of an optical trap in the channel unit using a resistance change of the semiconductor. The number of the cavity portions is at least 3 or more,
And the said cavity part is arrange | positioned periodically with a predetermined pitch. The optical element of any one of Claims 1-6. A plurality of the optical elements according to any one of claims 1 to 7,
The width (w) of the connection portion between the first upright portion and the second upright portion in the cavity portion is set to a different value between the plurality of optical elements. apparatus. In addition, it has an angle changer,
The optical element according to claim 1, wherein the angle changing unit is configured to change an incident angle of a light beam on the substrate. The angle changing unit includes a piezo element,
The optical element according to claim 9, wherein the piezo element is attached to the substrate to adjust an inclination of the substrate. The angle changing unit includes an electrostatic actuator,
The optical element according to claim 9, wherein the electrostatic actuator is configured to adjust an inclination of the substrate using an electrostatic attractive force. Optical switching device provided with an optical element according to any one of claims 9-11. The optical element according to any one of claims 1 to 7 and 9 to 11, and an adsorption element,
The adsorption element is configured to adsorb an object in the vicinity of the cavity part or the channel part.
Adsorption sensor. A spectroscopic method performed using the spectroscopic device according to claim 8,
Irradiating light across the plurality of cavities and the channel; and
Detecting the presence or absence of an optical trap in the channel portion;
Spectroscopic method comprising: An optical switching method performed using the optical switching device according to claim 12,
Irradiating light across the plurality of cavities and the channel; and
Changing the incident angle;
An optical switching method comprising: A substance detection method performed using the adsorption sensor according to claim 13,
Irradiating light across the plurality of cavities and the channel; and
Detecting a change in resonance characteristics of the adsorption sensor before and after the object is adsorbed to the adsorption element;
A substance detection method comprising: