JP2019058412A - Optical sensor device - Google Patents

Abstract

To enable spectrum analysis in a wide range of wavelengths while maintaining a single mode condition.SOLUTION: An optical sensor includes one wide-band light source 10 and a plurality of spectroscopic elements 20 provided around the wide-band light source. Each spectroscopic element includes a light introduction part 22 for introducing only a light of a predetermined wavelength band and a predetermined input angle, a light reception part 40 for receiving the introduced light, an optical waveguide part 30 for connecting the light introduction part and the light reception part, and a wavelength selection part 36 provided to the optical waveguide part, which transmits a predetermined wavelength band. The predetermined wavelength band transmitted by the wavelength selection part is set as at least two or more different wavelength bands for each spectroscopic element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical sensor device using an optical waveguide, and more particularly to an optical sensor device suitable for use in a blood glucose level sensor.

  Devices that use blood to measure blood glucose levels are drawing attention because they allow non-invasive measurements that do not require blood collection. For this reason, conventionally, various techniques have been proposed. Among them, a technique is known as a powerful technique which irradiates light from the skin surface to detect its reflected light and estimates the amount of glucose in the skin from the spectrum of the reflected light. Prior art devices used for this purpose were constructed in combination with bulk optics and were sized for use by the hospital bedside.

  Therefore, if the device can be sized so that it can be used by attaching it to the skin, its use can be widely extended not only to the medical site but also to the everyday scene. Optical waveguide technology is a strong candidate for the realization of the miniaturization of this device (see, for example, Patent Document 1). In particular, the use of silicon photonics using silicon as an optical waveguide material can contribute to the widespread use of this device due to the drastic miniaturization of optical circuits and the cost reduction by mass production of CMOS technology.

JP, 2011-245069, A

  Here, it has been recently found that it is useful to obtain a spectrum in a wide wavelength range of, for example, 1400 to 1600 nm for measurement of blood glucose level.

  Although it is advantageous to achieve single mode conditions in order to perform high precision spectroscopy, the optical waveguide can only meet single mode conditions in a narrow band.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an optical sensor device which enables spectral analysis in a wide range of wavelengths while maintaining single mode conditions. It is in.

  In order to achieve the object described above, the light sensor device of the present invention is configured to include one broadband light source and a plurality of spectral elements provided around the broadband light source.

  Each dispersive element includes a light introducing unit for introducing only light of a predetermined wavelength band and a predetermined input angle, a light receiving unit for receiving the introduced light, and an optical waveguide unit for connecting the light introducing unit and the light receiving unit. And a wavelength selection unit provided in the optical waveguide and transmitting a predetermined wavelength band. The predetermined wavelength band that transmits the wavelength selection unit is set as at least two or more different wavelength bands in each of the spectral elements.

  In the implementation of the above-described light sensor device, preferably, each light introducing unit is disposed concentrically around a broadband light source, and the predetermined input angle may be the same for all of the dispersive elements.

  Also, according to another preferred embodiment of the light sensor device of the present invention, the light separating element is divided into a first group and a second group. In the spectral element belonging to the first group, the light introducing part is disposed on a concentric circle of a first length whose center is a broad band light source, and the light receiving part and the optical waveguide part have a radius of the first length And the predetermined input angle is the same for all the dispersive elements. In the second group of light-splitting elements, the light introducing portion is disposed on a concentric circle of a second length whose center is a broadband light source, and the light receiving portion and the optical waveguide portion have a second radius. Located outside the concentric circles of length, and the predetermined input angle is the same for all dispersive elements.

  According to the optical sensor device of the present invention, a single mode condition of light propagating through the spectral element is measured by measuring the spectrum of the light output from the broadband light source with a plurality of spectral elements detecting light in a predetermined wavelength band. Enables spectral analysis over a wide range of wavelengths while maintaining

It is a schematic plan view of a 1st optical sensor apparatus. It is a typical sectional view of the 1st photosensor device. It is a schematic plan view of a 2nd optical sensor apparatus. It is a schematic plan view of a 3rd optical sensor apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the shapes, sizes, and arrangement relationships of respective components are merely schematically shown to the extent that the present invention can be understood. In addition, although preferred embodiments of the present invention will be described below, materials and numerical conditions of each component are merely preferred embodiments. Therefore, the present invention is not limited to the following embodiments, and many changes or modifications that can achieve the effects of the present invention can be made without departing from the scope of the configuration of the present invention.

First Embodiment
A light sensor device (hereinafter also referred to as a first light sensor device) according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 and 2 are a schematic plan view and a cross-sectional view, respectively, of the first light sensor device.

  The first light sensor device is configured to include a broadband light source 10 and a plurality of spectroscopic elements 20 provided on a support substrate 100. Each spectral element 20 includes a light introducing unit 22, an optical waveguide unit 30, and a light receiving unit 40. The broadband light source 10 and each spectral element 20 are formed by patterning the optical waveguide core 200 or the like.

The support substrate 100 is formed of, for example, a flat plate using single crystal silicon (Si) as a material. On the support substrate 100, a clad 300 which covers the upper surface of the support substrate 100 and which includes the optical waveguide core 200 is formed. The cladding 300 is formed using, for example, silicon oxide (SiO ₂ ) as a material. The optical waveguide core 200 is formed of Si having a refractive index higher than that of the cladding 300. As a result, the optical waveguide core 200 functions as a light transmission path, and the light input to the optical waveguide core 200 propagates in the propagation direction according to the planar shape of the optical waveguide core 200.

  In order to prevent the propagating light from escaping to the support substrate 100, the optical waveguide core 200 is preferably separated from the support substrate 100 by, for example, at least 3 μm or more.

  The broadband light source 10 emits light in a wide wavelength range of 1400 to 1600 nm. The broadband light source 10 is configured, for example, using a conventionally known laser diode (LD) or a light emitting diode (LED).

  The light output from the broadband light source 10 is diffusely reflected at a certain depth (indicated by C in FIG. 2) in the skin (indicated by B in FIG. 2). The diffusely reflected light is sent to each of the spectral elements 20. Each spectral element 20 handles light in one wavelength range in which the wavelength range of 1400 to 1600 nm is divided into wavelength ranges of several tens of nm.

  The irregularly reflected light is input to the light introducing unit 22 of each of the light separating elements 20. Glucose correlated with blood glucose levels is present in the skin at a depth of about 5 mm or more below the skin. For this reason, the broadband light source 10 and the light introducing unit 22 are disposed at an interval of about 5 mm or more.

  The light introduced into the light introducing portion 22 at a specific input angle in a wavelength range of several tens of nm is introduced. The light introduced into the light introducing unit 22 is sent to the optical waveguide unit 30. The light introducing unit 22 is, for example, a grating coupler, and is formed by providing a grating groove in the optical waveguide core 200. The grating grooves are formed by drilling from the upper surface of the optical waveguide core 200 to the middle in the thickness direction. A plurality of grating grooves are periodically formed along the length direction which is the light propagation direction. The period in which the grating grooves are formed is determined by the wavelength range of light handled by each dispersive element and the input angle.

  The optical waveguide unit 30 includes, for example, a single mode optical waveguide 34 and a tapered waveguide 32. The tapered waveguide 32 has a shape in which the width thereof sequentially changes from the width of the grating coupler constituting the light introducing portion 22 to the waveguide width of the single mode optical waveguide 34. The single mode optical waveguide 34 is provided with a wavelength selection unit 36. The wavelength selection unit 36 is formed of, for example, a grating element, and transmits only a specific wavelength. Although not shown here, it is possible to incorporate a conventionally known structure for separating diffracted light from input light, a polarization diversity structure, or the like.

  Since each spectral element 20 handles only one wavelength band, the single mode optical waveguide 34 can easily achieve the single mode condition in that wavelength band, and the wavelength selector 36 can be a light with good performance. It can be easily designed with wavelength filters.

  A plurality of sets of light of an input angle and a wavelength band are sent to the single mode optical waveguide 34, which are determined by the grating spacing of the grating couplers constituting the light introducing unit 22 and the like. Among these, only light of a specific wavelength band handled by the light separating element 20 is transmitted through the wavelength selection unit 36 and input to the light receiving unit 40.

  The light receiving unit 40 is configured using, for example, a conventionally known photodiode (PD).

  In addition, it is preferable to provide a thin film or the like for light shielding on the cladding 300 other than the region where the broadband light source 10 and the light introducing portion 22 of the first light sensor device are formed.

  In the first light sensor device, each spectral element 20 is provided around the broadband light source 10. The distance between the light introducing portion 22 included in each of the light separating elements 20 and the broadband light source 10 is equal to each other, that is, the light introducing portion 22 is provided on a concentric circle centering on the broadband light source 10. Further, the input angles handled by the light introducing portions 22 are designed to be equal to one another.

  Thereby, the light reflected by the same depth is input into the light receiving part 40 with which each spectroscopic element 20 is provided.

  Since each spectral element 20 handles different wavelengths, the wavelength distribution of light reflected in the skin can be measured as the entire first light sensor device.

  Among the plurality of spectral elements, one that handles the same wavelength band may be provided in consideration of variations in measurement results due to light propagation paths.

  The light introducing unit 22 is provided apart from the wide band light source 10 by a fixed distance. In order to miniaturize the light sensor device, the optical waveguide unit 30 and the light receiving unit 40 are disposed between the light introducing unit 22 and the broadband light source 10, that is, inside the concentric circle in which the light introducing unit 22 is disposed. That's good.

Second Embodiment
A light sensor device according to a second embodiment of the present invention (hereinafter, also referred to as a second light sensor device) will be described with reference to FIG. FIG. 3 is a schematic plan view of the second light sensor device.

  The second light sensor device has the same cross-sectional shape as the first light sensor device, but differs in planar shape.

  In each dispersive element 21 of the second light sensor device, the optical waveguide portion 31 and the light receiving portion 40 are on the opposite side of the light introducing portion 22 to the wide band light source 10, that is, concentric circles in which the light introducing portion 22 is disposed. Placed outside the In addition, in order to miniaturize the device, an optical path connecting the light introducing unit 22, the optical waveguide unit 31, and the light receiving unit 40 is formed in a curved shape.

  The first light sensor device is preferable to the second light sensor device in terms of miniaturization since the light waveguide portion 30 and the light receiving portion 40 are disposed inside the concentric circle in which the light introducing portion 22 is disposed. . On the other hand, in the second light sensor device, since the optical waveguide portion 31 and the light receiving portion 40 are disposed outside the concentric circle on which the light introducing portion 22 is disposed, the wiring for extracting the signal from the light receiving portion 40 is surfaced. It can be wired. For this reason, manufacture becomes easy compared with the 1st photosensor device which needs back wiring.

Third Embodiment
A light sensor device according to a third embodiment of the present invention (hereinafter also referred to as a third light sensor device) will be described with reference to FIG. FIG. 4 is a schematic plan view of the third light sensor device.

  The third light sensor device has the same cross-sectional shape as the first light sensor device and the second light sensor device but differs in planar shape.

  In the third photosensor device, the plurality of spectroscopic elements 20 and 21 are classified into a first group and a second group. Similarly to the first light sensor device, the light waveguide portion 30 and the light receiving portion 40 of the light separating element 20 included in the first group are disposed inside a concentric circle in which the light introducing portion 22 is disposed, and each light introducing portion The input angles handled by the unit 22 are set equal to one another. Further, as in the second light sensor device, the light waveguide portion 31 and the light receiving portion 40 are disposed outside the concentric circles in which the light introducing portion 22 is disposed, as in the second light sensor device. The input angles handled by the light introducing unit 22 are set equal to one another. Note that, in FIG. 4, illustration of the spectral element 21 included in the second group is partially omitted.

  The distance between the light introducing portion 22 included in each of the light separating elements 20 included in the first group and the broadband light source 10 is equal to each other and has a first length, that is, the light introducing portion 22 has a radius centered on the broadband light source 10 It is provided on a concentric circle of a first length. Further, the distance between the light introducing portion 22 included in each of the spectral elements 21 included in the second group and the broadband light source 10 is equal to each other, and the second length, that is, the light introducing portion 22 is centered on the broadband light source 10 A radius is provided concentrically of the second length. Furthermore, the first length and the second length are different from each other.

  By providing two types of distances between the light introducing portion 22 and the broadband light source 10, it becomes possible to cope with the individual differences in the depth of glucose correlated with the blood glucose level in the skin. In addition, you may provide three or more types of distance of the light introducing part 22 and the broadband light source 10 as needed.

  In addition, the first length and the second length may be equalized to enhance the measurement accuracy of light reflected at the same depth.

  According to the light sensor device according to each of the above-described embodiments, the light propagating through the spectral element is measured by measuring the spectrum of the light output from the broadband light source with a plurality of spectral elements that detect light in a predetermined wavelength band. Enables spectrum analysis over a wide range of wavelengths while maintaining single mode conditions of Further, by using a silicon optical waveguide, it is possible to mass-produce compact optical circuits at low cost.

  Moreover, although the example which estimates the quantity of the glucose in skin from the spectrum of reflected light mainly was demonstrated here, it is not limited to this, The scene where spectrum analysis in a wide range of wavelengths is desired by the same principle But it is available.

10 broadband light source
Reference Signs List 20 21 spectral element 22 light introducing part 30 31 optical waveguide part 32 tapered waveguide 34 single mode optical waveguide 36 wavelength selecting part 40 light receiving part 100 supporting substrate 200 optical waveguide core 300 cladding

Claims (7)

One broadband light source,
And a plurality of spectroscopic elements provided around the broadband light source,
Each of the spectral elements is
A light introducing unit for introducing only light of a predetermined wavelength band and a predetermined input angle;
A light receiving unit that receives the introduced light;
An optical waveguide unit connecting the light introducing unit and the light receiving unit;
A wavelength selection unit provided in the optical waveguide unit and transmitting the predetermined wavelength band;
A light sensor device, wherein the predetermined wavelength band which transmits the wavelength selection unit is set as at least two or more different wavelength bands for each of the light-splitting elements. Each of the light introducing parts is disposed concentrically around the wide band light source,
The optical sensor device according to claim 1, wherein the predetermined input angle is the same for all of the light separating elements. The optical sensor device according to claim 2, wherein the light receiving unit and the optical waveguide unit are disposed inside the concentric circle. The optical sensor device according to claim 2, wherein the light receiving unit and the optical waveguide unit are disposed outside the concentric circle. The spectral element is divided into a first group and a second group,
In the spectral element belonging to the first group,
The light introducing unit is disposed concentrically with a radius of a first length centered on the broadband light source,
The light receiving unit and the optical waveguide unit are disposed inside the concentric circle having a first length of radius, and
The predetermined input angle is the same for all the dispersive elements,
In the spectroscopic element belonging to the second group,
The light introducing unit is disposed on a concentric circle of a second length centered on the wide band light source,
The light receiving unit and the optical waveguide unit are disposed outside the concentric circle having a second length of radius.
as well as,
The optical sensor device according to claim 1, wherein the predetermined input angle is the same for all of the light separating elements. 6. The light sensor device according to claim 5, wherein the first length and the second length are different. The first length and the second length are equal,
The light sensor device according to claim 5, wherein the predetermined input angle in the light separating element belonging to the first group and the predetermined input angle in the light separating element belonging to the second group are equal.

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