JP2004340797A - Optical measuring device - Google Patents

Abstract

A highly accurate optical measuring device using evanescent light is provided.
A photonic crystal is provided on a measurement surface of an optical element for generating evanescent light, which is in contact with an object to be measured. Due to the optical band structure formed by the photonic crystal 107, the group velocity of the measurement light 106 near the fixed surface is measured and reduced. As a result, the time during which the evanescent light 109 and the device under test 108 interact with each other becomes longer, and even the evanescent light 109 which is originally weak can detect more signals indicating substance information of the device under test.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical evaluation device that evaluates optical characteristics of an object using evanescent light.
[0002]
[Prior art]
2. Description of the Related Art An evaluation method for measuring the optical characteristics of an object and analyzing composition information (quantity, quality, etc.) in the object is widely used taking advantage of the characteristics of nondestructive inspection. Among them, it is known that the near / mid-infrared wavelength of 0.8 to 20 μm contains many unique absorption wavelengths related to chemical bonds constituting various organic substances (such as biological substances). I have. Therefore, when light in this wavelength band is transmitted through a certain substance, the type and amount of the substance can be measured by measuring its absorption spectrum.
[0003]
In particular, the ATR method (Attenuated Total Reflection), in which evanescent light generated by reflection at the interface of an optical crystal such as ZnSe or Ge passes through a substance and its attenuation spectrum is used as detection means, is based on light absorption in the substance. It is suitable for measuring with high sensitivity. This is because the interaction between the evanescent wave and the measurement substance is sensitive to the optical properties of the measurement substance. Specifically, it is used in combination with a Fourier transform infrared spectrophotometer.
[0004]
FIG. 9 shows an example of a conventional mid-infrared light emitting / receiving device. The device under test 1008 is, for example, a living body, and the optical head 1003 also serves as a measurement head. The drive circuit 1004 is operated to emit the mid-infrared light 1006 from the light source 1001. The mid-infrared light 1006 enters the optical crystal 1003, repeats reflection, and is emitted to the light receiving element 1002. In this reflection portion, evanescent light 1009 is generated outside the optical crystal (see Patent Document 1).
[0005]
An object to be measured 1008 is in contact with the measurement surface of the optical crystal 1003. The evanescent light 1009 seeps into the object to be measured 1008, and light absorption occurs in the object to be measured 1008. As a result, information (light absorption) of the device under test is superimposed. The mid-infrared light enters the light receiving element 1002, generates a photocurrent, and is amplified by the signal processing circuit 1005.
[0006]
On the other hand, when the evanescent light permeates into the sample, the intensity y at a distance x from the surface is
y = Aexp (-x / D). . . . . . . . . . . . . . (Equation 1)
Given by Here, A is the intensity of evanescent light on the measurement surface (optical element surface), and D is
^{_{D = λ / 2π√ (n 1}} 2 sin 2 θ-n 2 2). . . . . . . . . (Equation 2)
Given by Here, λ is the measurement wavelength, n1 and n2 are the refractive indexes of the optical element and the object to be measured, respectively, and θ is the incident angle (this formula is valid only at a critical angle or more).
[0007]
[Patent Document 1]
JP-A-57-66741 [0008]
[Problems to be solved by the invention]
In order to obtain more information on a living body, it is desirable that A in (Equation 1) is larger, but evanescent light is originally weak light. It can also be seen from the above equation that the intensity decreases rapidly with increasing distance from the surface. As described above, in the measurement using an evanescent wave, sufficient information cannot be obtained from a living body (light absorption of a specific wavelength by a biological component), and it has been difficult to increase the measurement accuracy.
[0009]
In the above-described configuration, the measurement light comes into contact with the atmosphere. As a result, changes in absorption due to fluctuations of atmospheric carbon dioxide and the like are superimposed on the measurement light, and it has been difficult to obtain good signal-to-noise characteristics. Further, in manufacturing the apparatus, it is necessary to assemble each optical component with high precision such as optical axis alignment, and there is a problem that mass productivity is low.
[0010]
Further, there has been no semiconductor light emitting device that can emit light in this wavelength band at room temperature. Since the conventional semiconductor laser uses the transition between the conduction band and the valence band, Auger non-radiative recombination and overflow at the hetero interface have become problems, and it has been difficult to oscillate the mid-infrared at room temperature. Therefore, it was necessary to use a large-scale solid-state light source (such as a CO ₂ laser) or perform low-efficiency spectral analysis of a halogen bulb. Therefore, there is a problem that the device is large, consumes large power, and has a high manufacturing cost. If miniaturization, low power consumption, and low price can be achieved, it can be widely used for consumer use such as environmental analyzers, water quality analyzers, non-invasive biosensors, recycling and sorting equipment, and vegetable freshness sensors.
[0011]
[Means for Solving the Problems]
In order to solve the above problem, an optical measuring device according to claim 1 of the present invention is an optical measuring device using evanescent light, wherein an optical element for generating evanescent light has a measuring surface of the optical element made of a photonic crystal. It is characterized by having. According to this configuration, the group velocity, which is the substantial propagation speed of light energy, is reduced due to multiple reflection by a structure having a periodically changing refractive index such as a photonic crystal. As time increases, more information can be obtained from the substance. Therefore, highly sensitive and highly accurate measurement is possible.
[0012]
The photonic crystal described above is a material in which a high-refractive-index material and a low-refractive-index material are periodically formed on the order of a wavelength. In a normal crystal (a structure having no periodic refractive index change), there is a proportional relationship between the light frequency ω and the wave vector k. However, in the photonic crystal, this proportional relationship is broken, and the dispersion curve of ω-k forms a complex band structure instead of a straight line (just like an electron in a semiconductor having a periodic potential has a band structure). As a result, special light properties such as a decrease in the group velocity (dω / dk) are exposed.
[0013]
Next, in the optical measuring device according to claim 2 of the present invention, in the optical measuring device according to claim 1, the wavelength of light used for measurement is the maximum of a dispersion curve of an optical band structure formed by the photonic crystal. It is characterized by being near a point or a minimum point.
[0014]
According to this configuration, the group velocity of the measurement light can be almost zero, so that the measurement accuracy can be further improved.
[0015]
Next, in the optical measuring device according to claim 3 of the present invention, in the evanescent light generating optical element of the optical measuring device using evanescent light, the measuring surface of the optical element is composed of at least two or more types of photonic crystals. It is characterized by having.
[0016]
According to this configuration, since the control of the light distribution is improved, the measurement light can be localized near the surface in contact with the object to be measured. For the localization of the light, for example, total reflection at an interface between a photonic crystal including a surface in contact with an object to be measured and a photonic crystal not in contact with an object to be measured can be used. Such localization near the measurement surface enhances the generation of evanescent light interacting with the substance to be measured. Therefore, higher sensitivity and higher precision measurement can be realized.
[0017]
Next, in the optical measurement device according to claim 4, a first photonic crystal including a surface in contact with the object to be measured and a second photonic crystal not in contact with the non-measurement object are provided in the optical element, The period of the first photonic crystal in the direction perpendicular to the measurement surface is one period, and the period of the first photonic crystal in the direction perpendicular to the measurement surface is the measurement of the second periodic body. The period is different from the period in the direction perpendicular to the plane. That is, by simply changing the period of one type of photonic crystal to one period near the surface in contact with the object to be measured, the above-mentioned two types of photonic crystals can be formed substantially, as described above. Optical localization near the measurement surface is realized. This structure can be easily manufactured, for example, by changing the film thickness of a multilayer film, so that a highly accurate measuring device can be produced with good mass productivity.
[0018]
According to a fifth aspect of the present invention, there is provided the optical measuring device according to the first or third aspect, wherein the light emitting element and the light receiving element are formed on the package including the optical element by monolithic integration or hybrid integration. The semiconductor substrate is also provided. Thereby, the whole apparatus can be reduced in size and weight.
[0019]
Next, an optical measuring apparatus according to a sixth aspect is the optical measuring apparatus according to the fifth aspect, wherein a material of the semiconductor substrate is silicon. If a silicon substrate is used, integration of elements is easy and a large-diameter wafer is inexpensive, so that manufacturing cost can be reduced.
[0020]
Next, the optical measuring device according to claim 7 is the optical measuring device according to claim 1, wherein the wavelength used for measurement is near / mid-infrared light having a wavelength of 0.8 to 20 μm. Wavelength.
[0021]
The optical measuring device according to claim 8 is the optical measuring device according to claim 7, wherein the light-emitting element performs energy transition of electrons or holes between specific energy levels formed in the potential well. And emits photons.
[0022]
Such devices include quantum cascade-type semiconductor lasers developed recently (for example, F. Cappaso et. Al., “New Frontiers in Quantum Cascade Lasers and Applications”, IEEE Journal of Electronic Components, Limited, Electronic Components, Limited, Electronic Components, Electronic Components, Limited, Limited, Electronic Components, Limited, Limited, Limited, Limited, Limited, Limited, Limited) 6, No. 6, p. 931 (2000)). While the conventional semiconductor laser uses the conduction band / valence band transition between bands, this quantum cascade laser emits light at the conduction band transition between sub-bands formed in the quantum well. Therefore, the quantum cascade laser has little Auger non-radiative recombination and overflow at the hetero interface even in the mid-infrared region, and can easily achieve room-temperature oscillation. In addition, since the quantum cascade laser oscillates using the transition between sub-bands in the quantum well, the oscillation wavelength has good unity.
[0023]
By using such a quantum cascade laser as a mid-infrared light source, a light-emitting element can be integrated on a semiconductor substrate. Further, the optical characteristics of the photonic crystal provided in the optical element are determined by the optical band structure as described above, and thus have a large wavelength dependence. If the wavelength unity of the light source is low, the accuracy of the measurement decreases. However, by using a quantum cascade laser having good wavelength uniformity, highly accurate measurement can be realized even by using the above-described optical element having a photonic crystal.
[0024]
Next, an optical measuring device according to a ninth aspect is the optical measuring device according to the seventh aspect, characterized in that inter-subband photon absorption of a quantum well is used as the light receiving element.
[0025]
Further, it is desirable to use an element using intersubband photon absorption of a quantum well as the light receiving element. Unlike HgCdTe, which is often used for receiving mid-infrared light, it is not an inter-band photon absorption, so that the degree of freedom in material selection is increased, and the light receiving elements can be easily integrated on a semiconductor substrate.
[0026]
Next, an optical measuring device according to a tenth aspect is the optical measuring device according to the ninth aspect, wherein the quantum well is formed of silicon and silicon germanium.
[0027]
In this case, the light receiving element can be monolithically integrated on the silicon semiconductor substrate, and the number of assembling steps can be reduced, so that mass production can be achieved.
[0028]
With the integration as described above, the measurement light does not come into contact with the atmosphere. Therefore, a good signal-to-noise characteristic can be obtained without the absorption change due to the fluctuation of carbon dioxide in the atmosphere being superimposed on the measurement light. Further, the position of each optical component can be determined with mechanical accuracy by integration, and the optical adjustment process is simplified. As a result, mass productivity can be improved and the measuring device can be manufactured at low cost.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described more specifically with reference to embodiments.
[0030]
(First Embodiment)
FIG. 1 is a configuration diagram of the optical measurement device according to the first embodiment. The light source 101 is a CO ₂ laser. The drive circuit 104 is operated to emit the mid-infrared light 106 having a wavelength of 9.6 μm from the light source 101. The mid-infrared light 106 is incident on the ZnSe optical element 103 having the photonic crystal layer 107 on the measurement surface, is repeatedly reflected, and is emitted to the light receiving element 102. The object to be measured 108 is, for example, a living body, and the optical element 103 also serves as a measuring head. In the above-mentioned reflection portion, evanescent light 109 is generated outside the optical element 103. The object to be measured 108 is in contact with the surface of the photonic crystal layer 107. The evanescent light 109 oozes into the object 108, and light absorption occurs at a wavelength unique to the object 108. As a result, information (light absorption) of the device under test 108 is superimposed on the mid-infrared light 106. The mid-infrared light 106 enters the light receiving element 102, generates a photocurrent, and is amplified by the signal processing circuit 105.
[0031]
As shown in FIG. 2, in the first embodiment, the photonic crystal layer 107 is a multilayer film. Here, a laminated film of three layers of Ge and ZnSe is used. Since Ge and ZnSe are about 4.0 and about 2.4, respectively, for light of about 9 μm, the Ge layer 111 becomes a high refractive index layer and the ZnSe layer 112 becomes a low refractive index layer. Also, as is well known, Ge and ZnSe are transparent to light near 9 μm, and thus do not adversely affect the measurement. The photonic crystal layer 107, which is a multilayer film, was formed on ZnSe by PLD (pulse laser deposition).
[0032]
The thicknesses of the Ge layer 111 and the ZnSe layer 112 were set to the optical length / 4, and were set to 0.56 μm and 0.93 μm, respectively. In this configuration, the group velocity of the mid-infrared light 106 decreases due to the photonic band structure. That is, multiple reflection occurs in the mid-infrared light 106 incident on the photonic crystal layer 107 due to Bragg reflection of the multilayer film. As a result, the propagation speed of the effective light energy is reduced, so that the time for interacting with the object is increased, and more information (absorption by the object) of the object can be obtained. As described above, by forming photonic crystals having different periods on the surface of the optical element, highly accurate measurement can be performed.
[0033]
(Second embodiment)
Next, a second embodiment will be described. The basic configuration of the entire device is the same as that of the first embodiment. However, as shown in FIG. 3, in the photonic crystal layer 207 provided in the optical element 203, the refractive index periodic structure is formed not only in the stacking direction but also in the plane. Are also formed two-dimensionally. The in-plane period (period parallel to the measurement surface) was set to 0.75 μm, which is the optical length / 4, in consideration of the effective refractive index of the multilayer film as the Ge layer 211 / ZnSe layer 212. By periodically forming the refractive index change not only in the stacking direction but also in the plane, the group velocity of the measuring light in the photonic crystal layer 207 decreases not only in the stacking direction but also in the in-plane direction. Occurs. For this reason, measurement with higher accuracy than in the first embodiment has become possible.
[0034]
A method for manufacturing an optical element according to the second embodiment will be described. As shown in FIG. 4A, Ge thin films 211 and ZnSe thin films 212 are alternately formed on the ZnSe optical element 203 by using a PLD.
[0035]
Next, as shown in FIG. 4B, a periodic recess 215 of 0.45 μm square having a period of 0.75 μm was formed using photolithography and dry etching. Although not shown in FIG. 4B, the photoresist is still formed on the surface other than the holes. Next, the hole is filled with Ge using PLD to form a buried portion 216. At this time, Ge is deposited on the photoresist in portions other than the holes, so that unnecessary Ge can be easily removed by lift-off. After Ge removal, CMP (Chemical Mechanical Polishing) is performed to flatten the surface (FIG. 5C). As described above, the first photonic crystal layer 207 is formed. Finally, the entrance surface 221 and the exit surface 222 are formed by polishing, and the optical element 203 is completed (FIG. 5D).
[0036]
In the photonic band structure formed by the photonic crystal layer 207, if the measurement light is set at a frequency near the minimum point or the maximum point (dω / dk to 0) of the dispersion curve, the group velocity is further reduced. More information on the object to be measured can be obtained, and the measurement accuracy is significantly improved.
[0037]
(Third embodiment)
A third embodiment will be described. The basic configuration is the same as that of the second embodiment, but as shown in FIG. 5, the thickness of the Ge layer 311 inside the photonic crystal layer 307 provided in the optical element 303 is 0 (optical length / 4). The feature is that the film thickness of the outermost Ge layer 311a in the photonic crystal layer 307 is 1.12 μm, ie, optical length / 2, with respect to .56 μm. By changing the period only on the outermost surface of the photonic crystal, light can be localized on the outermost surface. This is because the light reflected from the measurement surface and traveling from the outermost surface layer to the inner photonic crystal causes total reflection at the boundary, so that the light is strongly confined to the outermost surface. This phenomenon is the same as the phenomenon in which a surface level is generated due to a difference in period at the surface in the energy band structure of electrons, and electrons are captured by the surface level.
[0038]
Changing only the period of the outermost Ge layer 311a can be easily realized by controlling the deposited film thickness in the multilayer film deposition process. That is, it can be said that the optical element has good mass productivity with a simple process.
[0039]
By localizing the light near the measurement surface as described above, evanescent light can be efficiently generated. As a result, in addition to the decrease in the group velocity, more information on the object to be measured (light absorption by the object to be measured) can be obtained, and more accurate measurement can be performed.
[0040]
(Fourth embodiment)
A fourth embodiment will be described. Although the basic configuration is the same as that of the second embodiment, as shown in FIG. 7, two types of first photonic crystal layers 407 and second photonic crystal layers 408 are provided on the measurement surface side of the optical element 403. Have been. The inner first photonic crystal layer 407 is formed into a multi-layered film (two layers each) of 0.56 μm and 0.93 μm each having a film thickness of the optical length / 4 of the Ge layer 411 and the ZnSe layer 412. As in the embodiment, the structure 416 is periodically embedded with a period of 0.75 μm and a period of 0.45 μm square. On the other hand, the second photonic crystal layer 408 close to the measurement surface is a multilayer film (two layers each) of 1.12 μm and 0.93 μm in which the film thickness of each of the Ge layer 421 and the ZnSe layer 422 is the optical length / 2. And a periodically embedded structure 416 of 0.45 μm square with a period of 0.75 μm.
[0041]
In this configuration, similarly to the third embodiment, light is strongly localized inside the second photonic crystal 408 near the surface by total reflection at the interface between the first photonic crystal 407 and the second photonic crystal 408. Can be done. In addition, the group velocity can be reduced by the dispersion characteristics of the second photonic crystal 408. As a result, information on the object to be measured (light absorption by the object to be measured) can be obtained effectively, and more accurate measurement has become possible.
[0042]
(Fifth embodiment)
FIG. 8 shows a fifth embodiment of the present invention. A silicon substrate 504 on which a light emitting element 501, a light receiving element 502, and an integrated circuit (LSI) 503 are integrated is mounted in a package 505.
[0043]
The light emitting element 501 is an InGaAs / InAlAs quantum cascade laser, and emits laser light having a wavelength of 9.6 μm. The threshold current of this semiconductor laser is about 100 mA, and the slope efficiency is 0.6 W / A. The driving current is supplied from the integrated circuit 503.
[0044]
By using a quantum cascade laser instead of a solid-state light source such as a CO ₂ laser or a low-efficiency halogen bulb as the mid-infrared light source, the light receiving and emitting mechanism can be integrated on the silicon substrate 504 and the package can be downsized.
[0045]
The epitaxial growth surface of the semiconductor laser 501 is fused to the silicon substrate 504 using an Au-Sn-based metal. By etching the silicon substrate 504, a recessed semiconductor laser mounting portion is formed. By setting the plane orientation of the silicon substrate 504 to (100), which is 9.7 degrees off in the <110> direction, a rising mirror 520 that bends the light of the semiconductor laser 501 in the direction perpendicular to the substrate surface is formed on the laser front emission side. (See, for example, Optronics, Inc., “Optical Technology Precision Processing Technology,” Part 2, Chapter 3, Section 2).
[0046]
It can be said that it is more preferable to provide a reflection film of Ag or Al on the surface of the rising mirror 520 in order to increase the reflectance at a wavelength of 9.6 μm.
[0047]
The light receiving element 502 is a mid-infrared light receiving element including a SiGe / Si quantum well (50 layers) formed on a silicon substrate 504. The mid-infrared light is detected by absorbing the mid-infrared light and performing a sub-band transition between the valence band sub-bands formed in the SiGe quantum well (see RP. _{G.Karunasiri et al., "Si 1} -x Ge x / Si multiple quantum well infrared detector", Appl. Phys. see, eg, Lett. 59 (20) p. 2588 (1991)). By using SiGe instead of HgCdTe, which is often used for receiving mid-infrared light, integration on a silicon substrate becomes possible. In addition, Si and Ge are abundant resources compared to HgCdTe and the like, so that low-cost manufacturing is easy.
[0048]
An electric signal converted from light in the signal light receiving element 502 is sent to the integrated circuit 503. The integrated circuit 503 includes a silicon bipolar circuit that drives the semiconductor laser 501 in a pulsed manner, and a CMOS amplifier circuit that processes a signal from the signal light receiving element 502. An earth electrode pad 510, a power supply electrode pad 511, a laser drive value setting electrode pad 516, and a signal extraction electrode pad 517 are formed for connection with the outside. This integrated circuit 503 operates with a power supply of +10 V.
[0049]
The package 505 is formed of an epoxy resin. The package 505 is provided with a ground lead electrode 506, a power lead electrode 507, a laser drive value setting lead electrode 512, a signal extraction lead electrode 513, and a heat dissipation metal 518. The lead electrodes 516, 517, 512, and 513 are mainly made of copper, and the surfaces are plated with Ni and Au. In addition, oxygen-free copper is used for the metal 518 for heat radiation. The substrate 504 is bonded to the heat dissipating metal 518 using a conductive adhesive 519. The electrode pads 510, 511, 516, and 517 are connected to the lead electrodes 506, 507, 512, and 513 by gold wires 508, 509, 514, and 515, respectively.
[0050]
The top of the package 505 is open, and an optical element 521 of ZeSe is attached to the opening. On the surface of the optical element 521, a first photonic crystal layer 522 and a second photonic crystal layer 523 are formed. These have the same structure as in the fourth embodiment, and have the effect of localizing light on the measurement surface and increasing the measurement sensitivity.
[0051]
With the above configuration, the size of the present light emitting / receiving device is 5 mm in width, 10 mm in length, and 4 mm in thickness (excluding the lead electrode), and an extremely compact mid-infrared region light emitting / receiving device is realized.
[0052]
As an operation method, first, a voltage of 10 V is applied to the lead electrode 507 to drive the integrated circuit. Next, by applying a voltage of 5 V or more to the lead electrode 512, a 200 mA pulse current (pulse width 1 μsec, duty 10%) flows through the semiconductor laser 501. As a result, about 60 mW of mid-infrared light 531 is emitted, and evanescent light 532 is generated on the surface of the optical element. By using such short pulses, the thermal influence on the object to be measured is reduced. The mid-infrared light 531 absorbed by the object to be measured generates a photocurrent by the light receiving element 502 and is converted by the integrated circuit 503 into a full-scale 10V voltage signal.
[0053]
When the measurement was actually performed, the noise was 1 mV or less, the dynamic range was 80 dB or more, and sufficient S / N characteristics were obtained. Such high characteristics are obtained because the light receiving element and the integrated circuit are extremely close to each other, so that not only electric noise is small but also noise due to absorption of carbon dioxide and the like in the atmosphere is reduced.
[0054]
【The invention's effect】
As described above, by using the present invention, a highly accurate optical measuring device using evanescent light can be manufactured at high productivity and at a low price, which is industrially useful.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an optical measurement device using evanescent light according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating an optical element according to the first embodiment of the present invention. FIG. 4 is a view showing an optical element according to a second embodiment of the present invention. FIG. 4 is a view showing a manufacturing process of an optical element according to a second embodiment of the present invention. FIG. 5 is an optical view showing a second embodiment of the present invention. FIG. 6 is a view showing an element manufacturing process. FIG. 6 is a view showing an optical element according to a third embodiment of the present invention. FIG. 7 is a view showing an optical element according to a fourth embodiment of the present invention. FIG. 9 is a diagram showing an optical measuring device according to a fifth embodiment of the invention. FIG. 9 is a diagram showing an example of a conventional optical measuring device using evanescent light.
101, 1001 Light source 102, 1002 Light receiving element 103, 203, 303, 403, 1003 Optical element 104, 1004 Drive circuit 105, 1005 Signal processing circuit 106, 1006 Mid-infrared light 107, 207, 307 Photonic crystal layer 108, 1008 DUTs 109, 1009 Evanescent light 111, 211, 311 Ge layer 112, 212 ZnSe layer 215 Concave part 216 Embedding part 221 Incident surface 222 Exit surface 311a Top surface Ge layer 407 First photonic crystal layer 408 Second photonic crystal 411 Ge layer 412 of the first photonic crystal 412 ZnSe layer 416 of the first photonic crystal Buried portion 421 Ge layer 422 of the second photonic crystal ZnSe layer 501 of the second photonic crystal 501 Quantum cascade laser 502 Collection of light receiving elements 503 Circuit 504 Silicon substrate 505 Package 506 Grounding lead electrode 507 Power supply lead electrode 508, 509, 514, 515 Gold wire 510, 511, 516, 517 Electrode pad 512 Laser drive value setting lead electrode 513 Signal extraction lead electrode 518 Heat radiation Metal 521 Optical element 522 First photonic crystal 523 Second photonic crystal 531 Mid-infrared light 532 Evanescent light

Claims (10)

An optical measuring device for generating evanescent light of an optical measuring device using evanescent light, wherein a measuring surface of the optical element is formed of a photonic crystal. 2. The optical measurement device according to claim 1, wherein the wavelength of the light used for the measurement is near a maximum point or a minimum point of a dispersion curve of an optical band structure formed by the photonic crystal. An optical element for generating evanescent light of an optical measuring apparatus using evanescent light, wherein a measurement surface of the optical element is composed of at least two or more types of photonic crystals. A first photonic crystal including a surface in contact with an object to be measured and a second photonic crystal not in contact with the non-measurement object are provided on the optical element, and the first photonic crystal is perpendicular to the measurement surface of the first photonic crystal. The period in the direction is one period, and the period of the first photonic crystal in the direction perpendicular to the measurement surface is different from the period of the second periodic body in the direction perpendicular to the measurement surface. 4. The optical measuring device according to claim 3, wherein 4. The optical measuring device according to claim 1, wherein the package including the optical element also includes a semiconductor substrate on which the light emitting element and the light receiving element are formed by monolithic integration or hybrid integration. 6. The optical measuring device according to claim 5, wherein the material of the semiconductor substrate is silicon. 6. The optical measuring device according to claim 1, wherein the wavelength used for the measurement is a near / mid-infrared wavelength of 0.8 to 20 μm. 8. The optical measurement apparatus according to claim 7, wherein the light emitting element emits a photon when electrons or holes make energy transition between specific energy levels formed in the potential well. The optical measurement device according to claim 7, wherein inter-subband photon absorption of a quantum well is used as the light receiving element. 10. The optical measurement device according to claim 9, wherein the quantum well is formed from silicon and silicon germanium.

Images