Optical sensors, optical detectors, and terahertz and infrared Fourier spectrometers

Abstract

This light sensor comprises: a vibration input unit that generates vibrations on the basis of an input signal; a vibration unit that is formed using a MEMS structure using a silicon material, that vibrates on the basis of vibrations transmitted by the vibration input unit, and that includes a both-end supported beam the resonant frequency of which changes due to the input of light; and a vibration detection unit that detects the vibrations of the both-end supported beam.

Description

[Technical field]

[0001] The present invention relates to an optical sensor, an optical detection device, and a terahertz / infrared Fourier spectrometer for detecting broadband light. This application claims priority based on Japanese Patent Application No. 2022-087832 filed in Japan on May 30, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Optical sensors are used everywhere in our daily lives, such as in various remote controls, and have become indispensable in our lives. Optical sensors are classified into photoelectric effect type and thermal effect type, of which pyroelectric detectors and bolometers are widely used as thermal effect types. The bolometer described above has a light absorption section that receives light and a detection section that detects temperature changes in the light absorption section. The light energy received by the light absorption section is converted into thermal energy, and the detection section detects the resistance value of the thermistor, which changes in response to temperature rise.

[0003] Conventional bolometers require cooling of the element and long-term heat integration to achieve high sensitivity. For this reason, it was difficult for conventional bolometers to simultaneously achieve the performance of "room temperature operation," "high speed," and "high sensitivity." In order to achieve the performance of "room temperature operation," "high sensitivity," and "high speed" in a bolometer, it is necessary to use a physical quantity other than the usual resistance value as the signal.

[0004] In recent years, research has been conducted on elements called MEMS (Micro Electro Mechanical Systems), which are formed using semiconductor microfabrication technology and have a microstructure that realizes mechanical operation. For example, Patent Document 1 and Non-Patent Document 1 disclose a highly sensitive bolometer-type optical sensor that uses MEMS.

[0005] The optical sensor described in Patent Document 1 and Non-Patent Document 1 includes a double-supported beam formed using MEMS made of GaAs (gallium arsenide) based on semiconductor microfabrication technology, a vibration input unit that inputs vibration to the double-supported beam, and a vibration detection unit that detects the vibration of the double-supported beam. This optical sensor detects the sensitive change in resonance frequency caused by thermal expansion due to a change in temperature of the beam based on the incidence of light, thereby achieving the performance of "room temperature operation", "high sensitivity" and "high speed".

[0006] Also, Non-Patent Document 2 describes an optical sensor configured with MEMS for detecting infrared rays. The optical sensor described in Non-Patent Document 2 has a MEMS structure configured with a paddle held by a thin lead, and is configured to detect the torsional mode of the MEMS structure based on a change in resonance frequency caused by the thermal effect of light irradiated from outside.

[0007] Non-Patent Document 3 describes an optical sensor configured with SOI (silicon on insulator) MEMS that detects terahertz rays. The optical sensor in Non-Patent Document 3 employs an SOI cantilever structure, and is configured to drive the vibration of the cantilever structure due to the thermal effect of externally irradiated light, and detect the vibration amplitude of the cantilever. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2018-146294 [Non-patent literature]

[0009] [Non-Patent Document 1] Y. Zhang, S. Hosono, N. Nagai, SH Song, and K. Hirakawa, “Fast and sensitive bolometric terahertz detection at room temperature through thermomechanical transduction”, Journal of Applied Physics 125, 151602 (2019); https: / / doi.org / 10.1063 / 1.5045256. [Non-Patent Document 2] XC Zhang, EB Myers, JE Sader, and ML Roukes, “Nanomechanical Torsional Resonators for Frequency-Shift Infrared Thermal Sensing” Nano Lett. 13, 1528 (2013); https: / / pubs.acs.org / doi / pdf / 10.1021 / nl304687p [Non-Patent Document 3] Froberger, K., et al. "SOI-based micro-mechanical terahertz detector operating at room-temperature." arXiv preprint arXiv:2204.03970 (2022).https: / / arxiv.org / pdf / 2204.03970.pdf Summary of the Invention [Problem to be solved by the invention]

[0010] When applying an optical sensor to a spectroscopy system or the like, it is desirable that there is no dead band in the sensitivity to the frequency of incident light. The bolometer-type optical sensor described in Patent Document 1 and Non-Patent Document 1 is composed of a MEMS formed on a GaAs substrate having polarity. With this optical sensor, there is a problem that when input light in the terahertz or infrared region passes through the GaAs substrate, a dead band occurs in which the detection sensitivity decreases in the terahertz to infrared region due to interaction with phonons in the GaAs crystal (see FIG. 14).

[0011] In addition, the response speed of a bolometer is determined by the thermal time constant. If the thermal conductivity is small, the thermal time constant is large, and the response speed of the sensor is reduced. In general, if a bolometer is formed in a small size, the thermal time constant of the element is reduced, and the response speed can be increased. However, GaAs material has a low thermal conductivity, and if it is formed to have a large light absorption area, the element size increases and the response speed deteriorates, which is an issue.

[0012] In addition, GaAs MEMS-based bolometers require growing a multi-layer GaAs / AlGaAs heterostructure substrate (see Fig. 15). The technology for growing GaAs / AlGaAs heterostructures is complicated, difficult to control, and expensive, which makes large-scale manufacturing and application of MEMS bolometers difficult.

[0013] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an optical sensor, an optical detection device, and a terahertz / infrared Fourier spectrometer that can detect light in a wide wavelength band, including visible light, infrared light, and terahertz waves, with high sensitivity. [Means for solving the problem]

[0014] One aspect of the present invention is an optical sensor comprising: a vibration input section that generates vibrations based on an input signal; a vibration section formed of a MEMS structure using a silicon material and having a double-supported beam that vibrates based on the vibration transmitted by the vibration input section and whose resonant frequency changes when light is input; and a vibration detection section that detects the vibration of the double-supported beam. Effect of the Invention

[0015] According to the present invention, light in a wide wavelength band including visible light, infrared light, and terahertz waves can be detected with high sensitivity. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram showing a configuration of a broadband photodetector according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a perspective view showing a configuration of an optical sensor. [Diagram 3] FIG. 1 is a diagram showing the transmission spectra of high-resistance SOI and GaAs. [Figure 4] FIG. 13 is a diagram showing the measurement results of the resonance spectrum of the optical sensor. [Diagram 5] FIG. 13 is a diagram showing a change in the resonance spectrum when heat is input to the optical sensor. [Figure 6] FIG. 13 illustrates the resonant frequency shift of an optical sensor as a function of input thermal power. [Figure 7] FIG. 13 is a diagram showing a change in resonance frequency when 530 nm visible light is input to an optical sensor. [Figure 8] FIG. 13 is a diagram showing a change in resonant frequency when 1.5 μm infrared light is input to an optical sensor. [Figure 9] FIG. 13 is a diagram showing a change in the resonant frequency when a terahertz wave of 0.3 THz is input to an optical sensor. [Figure 10] FIG. 13 is a diagram showing changes in resonance frequency when light of 0 to 5 THz is input to an optical sensor. [Figure 11] FIG. 13 is a diagram showing a change in resonance frequency when light of 0 to 20 THz is input to an optical sensor. [Figure 12]FIG. 13 is a diagram showing the measurement results of the frequency shift when the modulation frequency is changed. [Figure 13] FIG. 1 illustrates the performance of an optical sensor and a conventional sensor. [Figure 14] FIG. 1 is a diagram showing the performance of an optical sensor having a MEMS structure formed from conventional GaAs. [Figure 15] FIG. 1 is a diagram showing the configuration of a substrate having a conventional multilayer GaAs / AlGaAs heterostructure. [Figure 16] FIG. 1 is a diagram showing the configuration of a terahertz / infrared Fourier spectrometer to which an optical sensor is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] As shown in FIG. 1 and FIG. 2, the broadband light detection device 1 includes an optical sensor 10 that vibrates based on an input light L input from a light source R, a vibration detection device 20 that detects the vibration of the optical sensor 10, and a phase synchronization unit 30 that detects and adjusts the frequency of the vibration of the optical sensor 10 based on the detection value of the vibration detection device 20. The light source R may be any light source. For example, the input light L from the light source R may be, but is not limited to, natural light, solid-state light emission such as laser light or LED light, transmitted light transmitted through a sample, reflected light from an object, light emitted from a sample, and the like. The wavelength of the input light L is not particularly limited as long as it is included in the wavelength range detectable by the optical sensor 10, such as visible light, infrared light, or terahertz waves. The light source R may not be a component of the broadband light detection device 1.

[0018] The optical sensor 10 is formed in an optical element having, for example, a MEMS structure. In the following description, in the layer thickness direction of the optical sensor 10 (Z-axis direction in the figure), the +Z direction is described as the upper surface side, and the -Z direction is described as the lower surface side, etc. The above directions are defined for convenience and do not necessarily indicate the directions in the usage form of the optical sensor 10.

[0019] The optical sensor 10 includes a substrate portion 13 formed in a plate shape, a vibration portion 11 formed on the substrate portion 13, and a sacrificial layer 12 for isolating the vibration portion 11 from the substrate portion 13. The optical sensor 10 is configured, for example, from a high-resistance SOI (Silicon on Insulator) wafer formed from silicon material (Si) used in semiconductor elements.

[0020] The sacrificial layer 12 is formed of a silicon oxide film (SiO2). The sacrificial layer 12 is formed into a pair of first legs 12A and second legs 12B so as to support the vibration part 11. The pair of first legs 12A and second legs 12B are formed to have a rectangular cross section in a plan view. The vibration part 11 formed in a plate shape is provided on the upper surface 12C side of the sacrificial layer 12. The vibration part 11 is formed of a silicon (Si) material. The vibration part 11 has a double-supported beam 11A formed in a flat plate shape by extending so as to bridge the pair of sacrificial layers 12. A first support part 11B supported by the first leg 12A is provided in a connected state on one end side of the double-supported beam 11A. A second support part 11C supported by the second leg 12B is provided in a connected state on the other end side of the double-supported beam 11A. The double-supported beam 11A vibrates based on the vibration transmitted by a vibration input part 16 described later.

[0021] The high-resistance SOI used in the optical sensor 10 is, for example, p-type with a crystal plane orientation (100) and a resistivity exceeding 1000 ohm*cm, and has a stable transmission spectrum over a wide frequency band (see FIG. 3). Therefore, the optical sensor 10 made of SOI can perform stable, highly sensitive optical measurement over a wide band. The optical sensor 10 made of SOI has a higher thermal conductivity than conventional optical sensors made of GaAs, and can realize a high-speed bolometer.

[0022] The doubly supported beam 11A may be used as it is if it can absorb the wavelength band of the light to be measured. In addition, in order to achieve a constant absorption rate in a wide wavelength band, it is preferable to provide a light absorbing section 15 formed in a rectangular thin film shape. This light absorbing section 15 can be appropriately selected and used from a metal film, an absorbing film with a high absorption rate due to a metasurface plasmon structure, a doping film in which impurities are introduced into the surface of the doubly supported beam 11A and the sheet resistance is matched to the vacuum electromagnetic wave resistance, etc. In addition, when the above-mentioned light absorbing section 15 is formed from a metal film, it can be formed as a metal film by evaporating nickel or a nickel-chromium (NiCr) alloy. The light absorbing section 15 increases in temperature when light is input, and transmits the temperature to the doubly supported beam 11A. The impedance of the light absorbing section 15 matches the impedance of the input light or electromagnetic wave, and converts the incident light into heat and transmits it to the doubly supported beam 11A. The light absorbing section 15 transmits the temperature to the doubly supported beam 11A, causing the doubly supported beam 11A to expand, thereby changing the resonance frequency. The light absorbing section 15 may be provided at any position as long as it can expand the beam 11A at both ends and change the resonant frequency, but it is preferable to provide it at the center of the beam 11A at both ends. A vibration input section 16 that inputs vibration to the beam 11A is formed on the upper surface of the first support section 11B. A vibration detection section 17 that detects the vibration of the beam 11A is formed on the upper surface of the second support section 11C.

[0023] The vibration input section 16 is formed by, for example, a pair of electrodes 16A, 16B. The pair of electrodes 16A, 16B are formed by being laminated in the layer thickness direction on the upper surface side of the double-supported beam 11A, and are provided at one end in the longitudinal direction of the double-supported beam 11A, that is, on the side of the first support section 11B in FIG. 2. An insulating layer 16C formed of a piezoelectric body is formed between the layers of the pair of electrodes 16A, 16B. The vibration input section 16 is formed as a piezoelectric element that generates an electrostatic force between the pair of electrodes 16A, 16B based on a voltage inputted so as to generate a potential difference between the pair of electrodes 16A, 16B, and the insulating layer 16C is deformed. The vibration input section 16 generates vibration based on an input signal outputted from a vibration generating section 36 described later. The vibration input section 16 vibrates by inputting an input signal based on a voltage of a predetermined frequency generated by the vibration generating section 36 to the pair of electrodes 16A, 16B. The vibration input section 16 is capable of transmitting the generated vibration to the both-supported beam 11A, thereby vibrating the both-supported beam 11A.

[0024] The vibration input unit 16 may be configured as an electrostatic element that applies a potential difference between the beam 11A and the substrate unit 13 and inputs vibration to the beam 11A based on the electrostatic effect, in addition to the piezoelectric element. The vibration input unit 16 may also be configured as an electromagnetic actuator that provides electrodes on the beam 11A and inputs vibration to the beam 11A based on the Lorentz force that is generated when a current flows through the electrodes in a magnetic field generated around the beam 11A. The electromagnetic actuator may be configured to pass an AC current through an electrode in a DC magnetic field, or may be configured to pass a DC current through an electrode in an AC magnetic field.

[0025] The vibration detection unit 17 is formed, for example, by a pair of electrodes 17A and 17B. The vibration detection unit 17 has the same configuration as the vibration input unit 16. The pair of electrodes 17A and 17B are formed by being stacked in the layer thickness direction on the upper surface side of the both-supported beam 11A, and are provided at the other end in the longitudinal direction of the both-supported beam 11A, that is, on the side of the support unit 11C in FIG. 2. An insulating layer 17C formed of a piezoelectric body is formed between the layers of the pair of electrodes 17A and 17B. The vibration detection unit 17 is formed by a pair of electrodes 17A and 17B. The vibration detection unit 17 is formed on a piezoelectric element that generates a potential difference between the pair of electrodes 17A and 17B when the insulating layer 17C is deformed. In the vibration detection unit 17, the insulating layer 17C is deformed based on the vibration of a predetermined frequency generated in the both-supported beam 11A, and an output signal based on a voltage of a predetermined frequency is output based on the deformation of the insulating layer 17C.

[0026] The vibration detection unit 17 may be formed of a piezoresistance element that detects a resistance that changes according to a stress generated based on the vibration of the both-supported beam 11A, other than a piezoelectric element. The vibration detection unit 17 may be a laser Doppler vibrometer that receives a reflected light of a laser beam irradiated to the both-supported beam 11A and detects the vibration of the both-supported beam 11A based on the Doppler effect.

[0027] The vibration detection device 20 amplifies the signal output from the vibration detection section 17 and outputs the detection signal to the phase synchronization section 30. The phase synchronization section 30 is configured as a general phase synchronization circuit. The phase synchronization section 30 includes, for example, a phase comparator 32 that inputs the output value of the detection signal output from the vibration detection device 20, a low-pass filter 34 connected to the downstream side of the phase comparator 32, and a vibration generation section 36 that is connected to the downstream side of the low-pass filter 34 and is connected to the phase comparator 32 and the vibration input section 16.

[0028] The phase comparator 32 compares the phase of the detection signal output from the vibration detection device 20 with that of a reference signal, and outputs a signal indicating the phase difference. The low-pass filter 34 receives the signal output from the phase comparator 32, and outputs an output signal that blocks high frequencies from the signal. The vibration generating unit 36 ​​outputs a signal whose frequency is changed in a direction that cancels the signal from the low-pass filter 34. The signal output from the vibration generating unit 36 ​​is input to the vibration input unit 16 of the optical sensor 10 as an input signal, and is also input to the phase comparator 32 as a reference signal. The signal output from the vibration generating unit 36 ​​is input to the vibration input unit 16 as an input signal having the resonance frequency of the double-supported beam 11A of the optical sensor 10. The vibration input unit 16 generates vibration based on the input signal, and vibrates the double-supported beam 11A.

[0029] Next, we will explain the operation of the broadband photodetector 1. When no light is input to the optical sensor 10, the double-supported beam 11A vibrates at a natural resonant frequency. The initial value ω0=f0 / 2π of the angular frequency corresponding to the resonant frequency f0 is given by the following formula (1).

[0030]

number

[0031] where Young's modulus of the double-supported beam 11A is E, density is ρ, and constant according to mode is μ n , the span length of the both-supported beam 11A is L, and the thickness of the both-supported beam 11A is t. When light is irradiated from the light source R to the optical sensor 10, the light irradiated to the both-supported beam 11A is converted to heat in the light absorption section 15. The heat generated in the light absorption section 15 is transferred to the both-supported beam 11A. When the temperature of the both-supported beam 11A rises, the both-supported beam 11A thermally expands. Since one end of the both-supported beam 11A is restrained by the first support section 11B and the other end is restrained by the second support section 11C, the both-supported beam 11A is compressed in the longitudinal direction in response to the thermal expansion, and a stress σ is generated inside. The angular frequency ω0(σ)=f0 / 2π corresponding to the resonance frequency f0 of the both-supported beam 11A when the stress σ acts is expressed by the following formula (2).

[0032]

number

[0033] As shown in formula (2), the angular frequency ω0 (σ) corresponding to the resonance frequency f0 changes linearly with an increase in the thermal stress σ (<0). Here, if the resonance frequency of the both-supported beam 11A is detected based on the optical sensor 10, the power of the input light can be calculated. When the resonance frequency of the both-supported beam 11A to which light is input changes, the phase synchronization unit 30 adjusts the signal of the changed resonance frequency so that it is output from the vibration generating unit 36. The resonance frequency of the both-supported beam 11A can be obtained by observing the signal output from the vibration generating unit 36. Therefore, according to the wideband light detection device 1, the resonance frequency of the both-supported beam 11A shifts based on the light input to the optical sensor 10, so that the input of light can be detected.

[0034] In order to detect minute changes in the resonance frequency f0 based on the optical sensor 10, it is desirable that the mechanical resonance in the double-supported beam 11A has a quality factor (Q value) that represents the state of vibration as high as possible. B is the Boltzmann constant, T is the temperature, f0 is the resonant frequency, k is the spring constant of the double-supported beam 11A, Q is the Q value, and A is the amplitude. The frequency noise density n f The relationship between the Q value and the resistance is expressed by the following formula (3).

[0035]

number

[0036] 4 shows the measurement results of the resonance spectrum of the optical sensor 10 measured based on the wideband photodetector 1. According to the measurement results, the Q value of the optical sensor 10 was approximately 17,000. The optical sensor 10 exhibits a value more than twice as high as that of a conventional MEMS optical sensor formed from GaAs. Therefore, the optical sensor 10 is capable of measuring the frequency of light with less noise and greater precision than the conventional MEMS optical sensor formed from GaAs.

[0037] FIG. 5 shows the change in the resonance spectrum when heat is input to the optical sensor 10. As shown in the figure, the optical sensor 10 generates thermal stress and softens based on the input of light, and the resonance frequency decreases accordingly. FIG. 6 shows the function of the resonance frequency shift of the optical sensor 10 corresponding to the input thermal power. In the figure, (A) shows the measurement result using a doubly supported beam 11A formed with dimensions of 100 μm × 30 μm × 2.5 μm. As can be seen in FIG. 5, the frequency shift increases linearly with the increase in heat output, so the normalized thermal response of this sample is expressed by the following equation (4).

[0038]

number

[0039] Such thermal response can be adjusted by forming the double-supported beam 11A to be thin or by forming the span length to be long. In FIG. 6, (B) shows the measurement result when a double-supported beam 11A formed to be 0.8 μm thick is used. As shown in the figure, (B) shows a frequency shift compared to (A), and the thermal response R is about 26.5 W. -1 The measured thermal response was close to that of the optical sensor made of GaAs.

[0040] FIG. 7 shows the change in the resonance frequency when 530 nm visible light is input to the optical sensor 10. FIG. 8 shows the change in the resonance frequency when 1.5 μm infrared light is input to the optical sensor 10. FIG. 9 shows the change in the resonance frequency when 0.3 THz terahertz waves are input to the optical sensor 10 by a terahertz wave multiplier. FIG. 10 shows the change in the resonance frequency when light from a thermal light source (light bulb) is input to the optical sensor 10 via a far-infrared pass filter (cut frequency 5 THz) (i.e., the input light is light of 0 to 5 THz). FIG. 11 shows the change in the resonance frequency when light from a thermal light source (light bulb) is input to the optical sensor 10 via a far-infrared pass filter (cut frequency 20 THz) (i.e., the input light is light of 0 to 20 THz). As shown in the figure, the optical sensor 10 can detect the resonance frequency that changes based on the input of light. It can be seen that the optical sensor 10 has sensitivity to light in the visible light and infrared light frequency bands.

[0041] The optical sensor 10 can detect light in a predetermined frequency band at high speed. The photothermal response speed of the optical sensor 10 is determined based on its thermal time constant. If the specific heat of silicon is c and the thermal conductivity is κ, the thermal time constant of the optical sensor 10 is expressed by the following formula (5).

[0042]

number

[0043] The response speed of the optical sensor 10 is 1 / τ, so the smaller τ is, the faster the response of the optical sensor 10. To demonstrate the high speed response speed of the optical sensor 10, the modulation frequency of the input light was modulated and the shift in the resonant frequency was measured.

[0044] 12 shows the measurement results of the frequency shift Δf when the modulation frequency is changed. As shown in the figure, when comparing the optical sensor 10 with an optical sensor of the same size formed from a conventional GaAs, the thermal time constant of the optical sensor 10 was about 35 μs, while the thermal time constant of the optical sensor formed from the conventional GaAs was about 100 μs. As shown by this measurement result, when comparing the optical sensor 10 of the same shape with an optical sensor formed from a conventional GaAs, it is found that the thermal response of the optical sensor 10 is about three times faster than the thermal response of the optical sensor formed from the conventional GaAs.

[0045] As shown in Fig. 13, the optical sensor 10 has a detection speed (Hz) that is 100 to 1000 times faster than conventional thermal sensors that utilize changes in resistance or capacitance, while having the same sensitivity. The broadband photodetector 1 has an optical sensor 10 with a MEMS structure formed from an SOI material, and can realize a bolometer with high resistance and high light transmittance at low cost. The broadband photodetector 1 can realize a high-performance bolometer that operates at room temperature based on the optical sensor 10 and has a wide band, high sensitivity, high speed, and low cost.

[0046] Optical sensor 10 is formed using an SOI substrate, and therefore has high transmittance over a wide frequency range, and is capable of measuring light ranging from visible light to infrared and terahertz waves, making it possible to realize a sensor that operates at room temperature, is fast, and highly sensitive. Optical sensor 10 uses an SOI substrate structure that is less expensive than a GaAs heterostructure, which has a complicated growth process, and therefore MEMS bolometers can be mass-produced at low cost. Optical sensor 10 uses general silicon semiconductor technology, and therefore can be easily mass-produced.

[0047] The optical sensor 10 has high sensitivity to light in a wide wavelength band, from visible light to infrared and terahertz waves, and therefore has a detection speed approximately three times faster than a conventional MEMS optical sensor formed in the same shape from GaAs. The optical sensor 10 is formed from a silicon-based material, which simplifies the growth process and allows it to be formed at low cost. The broadband photodetector 1 to which the optical sensor 10 is applied has no dead band in which detection sensitivity decreases in the terahertz to infrared region, and can realize a broadband, high-speed, and high-sensitivity photodetector, spectrometer, and biological imaging device.

[0048] In addition, when attempting to form a doubly supported beam resonator type optical sensor using silicon-based materials, there was a problem that the internal stress of the beam structure deposited by the physical film deposition method was large. However, the present inventors have found that the above-mentioned internal stress problem can be solved by adopting a MEMS structure formed of a crystalline SOI material (for example, a single crystal SOI substrate) with small internal stress. In this way, when a MEMS doubly supported beam structure formed of an SOI material is used, the performance of the optical sensor can be further improved. For example, the example described in the above Non-Patent Document 2 adopts a-Si that is physically deposited, so the internal stress of the MEMS structure is relatively large. For this reason, only a torsion mode with insufficient temperature sensitivity can be used. Compared with the example described in this Non-Patent Document 2, the temperature sensitivity of the above optical sensor 10 is about 20 times higher. Note that Non-Patent Document 3 describes an example using an SOI substrate, but this does not take into consideration the internal stress of the beam structure as described above. The example described in Non-Patent Document 3 adopts a cantilever structure, so the initial stress inside the structure is irrelevant. In addition, Non-Patent Document 3 does not describe the crystallinity of the material. Furthermore, in the example described in Non-Patent Document 3, a cantilever structure is used, so the temperature sensitivity is approximately 10 nW / Hz 0.5 , which is more than 10 times better than the optical sensor 10 described above.

[0049] The broadband light detection device 1 to which the optical sensor 10 is applied can be applied to industrial fields that use near-infrared, infrared, and terahertz frequency bands. The broadband light detection device 1 to which the optical sensor 10 is applied can realize a terahertz / infrared Fourier spectrometer (FTIR), which is an essential device in the fields of materials, chemistry, pharmaceuticals, and biotechnology. The FTIR to which the optical sensor 10 is applied will be described below. In the following description, the same names and symbols will be used for the same configurations as in the above embodiment, and duplicate descriptions will be omitted as appropriate.

[0050] As shown in FIG. 16, the FTIR 100 includes a broadband light detection device 1 having a light sensor 10, a lens unit N, a light source R, an interference light generation unit U that generates interference light, and a calculation device 40 that analyzes the light detected by the broadband light detection device 1. The FTIR 100 is configured as a spectrometer that measures the interference waveform of light using an interferometer and measures the intensity distribution of the spectrum of light by Fourier transforming the measured value. When the FTIR 100 is used, a sample S is set in the broadband light detection device 1, and the FTIR 100 can examine the optical characteristics of the sample S. Note that the sample S is placed between the semi-transparent mirror U1 of the interference light generation unit U and the lens unit N in FIG. 16, but is not limited to this placement and may be placed at any position where spectroscopic measurement is possible. The lens unit N is formed in a lens shape using silicon, and collects the input light and inputs it to the light sensor 10. The calculation device 40 analyzes and outputs the spectrum of the light input to the light sensor 10. The arithmetic unit 40 is, for example, an information processing terminal device constituted by a personal computer or the like.

[0051] The interference light generating unit U is, for example, a Michelson interferometer, and includes a semi-transparent mirror U1, a first reflecting mirror U2 formed on a fixed mirror, and a second reflecting mirror U3 formed on a movable mirror that can move freely. The semi-transparent mirror U1 receives light L1 input from the light source R in an oblique direction and splits the light L1 into two light beams: a first reflected light beam L2 and a second transmitted light beam L3. The first light beam L2 is reflected by the first reflecting mirror U2 and returns to the semi-transparent mirror U1. The second light beam L3 is reflected by the second reflecting mirror U3 and returns to the semi-transparent mirror U1.

[0052] The first light L2 and the second light L3 are combined in the semi-transparent mirror U1. The second reflecting mirror U3 is movable in the optical path direction, and an optical path difference occurs between the optical path length of the second light L3 and the optical path length of the first light L2. Therefore, a phase difference occurs between the first light L2 and the second light L3 in the semi-transparent mirror U1, and an interference light L4 occurs in the semi-transparent mirror U1. The interference light L4 generated in the semi-transparent mirror U1 is collected in the lens unit N formed by a silicon lens and input to the optical sensor 10. The interference light L4 input to the optical sensor 10 vibrates the double-supported beam 11A, and the vibration is detected by the vibration detection device 20. The resonance frequency of the double-supported beam 11A changes based on the interference light L4. The phase synchronization unit 30 detects the frequency of the vibration of the optical sensor 10. The detection value detected by the phase synchronization unit 30 is input to the calculation device 40. The arithmetic unit 40 analyzes the spectrum of the light L1 based on the detection value detected by the phase synchronization unit 30. The arithmetic unit 40 performs Fourier analysis of the interference waveform of the interference light L4 at the detection value, and performs spectrum analysis of the light L1 output from the light source R. The arithmetic unit 40 outputs the spectrum of the light L1 for each wavelength component.

[0053] Since the modulation frequency of the light caused by the movement of the second reflecting mirror U3 is proportional to the frequency of the light and the moving speed of the second reflecting mirror U3, the scanning speed of the FTIR 100 depends on the detection speed of the optical sensor. The light intensity modulation frequency of the FTIR 100 is calculated by fm=2*f / c*v, where f is the frequency of the light, c is the speed of the light, and v is the speed of the moving mirror. For example, if the light is 10 μm infrared (frequency 30 THz) and the speed of the moving mirror is 10 mm / s, the modulation frequency of the light is 2 kHz.

[0054] The FTIR 100 to which the optical sensor 10 is applied has a detection speed of about 100 to 1000 times faster than that of a pyroelectric detector used in conventional FTIR, and can measure the spectral distribution of light at high speed and high sensitivity. The FTIR 100 can realize a multichannel spectrometer that analyzes the spectral distribution of light in the near-infrared, infrared, and terahertz frequency bands at high speed and high sensitivity. The interference light generating unit U may be replaced with a Michelson interferometer or other interferometer that generates interference light. The optical sensor 10 in the FTIR 100 may be an array of elements, and by integrating the circuit of the vibration detection unit, it is possible to realize an imaging element and thermography that can detect near-infrared, infrared, and terahertz waves at high speed, and can be applied to night driving support devices, etc.

[0055] The above-mentioned arithmetic device 40 is realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The program may be stored in a storage device such as an HDD (Hard Disk Drive) or flash memory provided in the arithmetic device 40 in advance, or may be stored in a removable storage medium such as a DVD or CD-ROM, and installed by mounting the storage medium in a drive device.

[0056] Although the present invention has been described above using the embodiments, the present invention is not limited to these embodiments, and various modifications and substitutions can be made without departing from the scope of the present invention. The configurations described in the above embodiments may be mutually substituted. [Explanation of symbols]

[0057] 10. Optical Sensor 11 Vibration section 11A Double supported beam 15 Absorption section 16 Vibration input section 17 Vibration detection unit 20 Vibration detection device 30 Phase synchronization section 36 Vibration generating unit 40 Arithmetic unit L Input light L1 light R light source

Claims

1. a vibration input unit that generates vibrations based on an input signal; a vibration section having a doubly supported beam formed by a MEMS structure using a silicon material, vibrating based on the vibration transmitted by the vibration input section and having a resonant frequency that changes when light is input; a vibration detection unit that detects vibration of the double-supported beam, The MEMS structure is formed of a high-resistance SOI (Silicon on Insulator) substrate (excluding the phononic crystal); Light sensor.

2. The MEMS structure is formed of an SOI substrate having a flat surface. The optical sensor of claim 1 .

3. The double-supported beam is provided between the vibration input unit and the vibration detection unit, and has a light absorption unit to which temperature is transmitted by inputting light.

3. The optical sensor according to claim 1 or 2.

4. The vibration input portion is formed by a piezoelectric element provided on one end side of the double-supported beam in the longitudinal direction. The optical sensor according to claim 3 .

5. The vibration input portion is formed by an electrostatic element provided on one end side of the double-supported beam in the longitudinal direction. The optical sensor according to claim 3 .

6. The vibration detection unit is formed of a piezoelectric element provided on the other end side of the double-supported beam in the longitudinal direction. The optical sensor according to claim 3 .

7. The vibration detection unit is formed of a piezoresistance element provided on the other end side of the double-supported beam in the longitudinal direction. The optical sensor according to claim 3 .

8. The MEMS structure includes: A substrate portion formed in a flat plate shape; A pair of sacrificial layers formed on the substrate portion; The vibration unit is made of a silicon material and has the two-sided beam formed in a flat plate shape so as to bridge the pair of sacrificial layers. The optical sensor according to claim 3 .

9. an optical sensor including a vibration input unit that generates vibrations based on an input signal, a vibration unit formed of a MEMS structure using a silicon material, that vibrates based on the vibration transmitted by the vibration input unit, and that has a double-supported beam whose resonance frequency changes when light is input, and a vibration detection unit that detects the vibration of the double-supported beam; a vibration detection device that amplifies and outputs the vibration of the optical sensor; a phase synchronization unit that detects a frequency of vibration of the optical sensor based on an output value of the vibration detection device, The MEMS structure is formed of a high-resistance SOI substrate (excluding phononic crystals); Light detection device.

10. The MEMS structure is formed of an SOI substrate having a flat surface.

10. The optical detection device according to claim 9.

11. an optical sensor including a vibration input unit that generates vibrations based on an input signal, a vibration unit formed of a MEMS structure using a silicon material, that vibrates based on the vibration transmitted by the vibration input unit, and that has a double-supported beam whose resonance frequency changes when light is input, a light absorption unit that transmits temperature to the double-supported beam when light is input, and a vibration detection unit that detects the vibration of the double-supported beam; a light source for inputting input light to the optical sensor; a vibration detection device that amplifies and outputs the vibration of the optical sensor; a phase synchronization unit that detects a frequency of vibration of the optical sensor based on an output value of the vibration detection device; a calculation unit that analyzes the spectrum of the light based on the detection value detected by the phase synchronization unit, The MEMS structure is formed of a high-resistance SOI substrate (excluding phononic crystals); Terahertz and infrared Fourier spectrometer.

12. The MEMS structure is formed of an SOI substrate having a flat surface. The terahertz / infrared Fourier spectrometer according to claim 11.

13. The resistivity of the SOI substrate is greater than 1000 Ω cm; The optical sensor of claim 1 .

Images