Mid- and far-infrared broadband detection system based on whispering gallery mode microcavity

Abstract

The present invention provides a mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity. This system relates to the field of infrared detection technology and includes: a whispering gallery mode microcavity portion, wherein the surface of the whispering gallery microcavity structure is coated with a mid- and far-infrared light absorbing material; a laser light source portion for emitting detection light; a photoelectric detection portion for detecting light signals in the whispering gallery mode microcavity; and a signal generator portion for supporting a mixer in providing a voltage signal to a voltmeter. The present invention converts light energy into heat energy by coating the mid- and far-infrared light absorbing material on the surface of the on-chip whispering gallery microcavity. The heat is then conducted from the absorption layer into the microcavity waveguide, causing a change in the waveguide temperature. Under the influence of the thermo-optical effect, the equivalent refractive index of the microcavity mode changes, causing the resonant frequency to drift, resulting in a change in the transmitted light power of the microcavity. The photoelectric detector then converts the light power into an electrical signal, achieving highly sensitive detection of mid- and far-infrared light intensity at room temperature.

Description

Technical Field

[0001] The present invention relates to the field of infrared detection technology, and in particular to a mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity. Background Art

[0002] Electromagnetic waves in the mid- and far-infrared bands, particularly the terahertz band, have long been understudied and underdeveloped compared to microwaves and light waves in the visible and near-infrared bands due to a lack of high-performance radiation sources and effective, highly sensitive detection methods. However, the mid- and far-infrared bands hold significant application prospects in areas such as public safety, wireless communications, bioeffects, biomedical imaging, and information technology. For example, spontaneous radiation emitted by the human body falls within the mid- and far-infrared bands. Besides being used to measure body temperature, the rich information contained in its spectrum is expected to reveal a person's health and psychological state. Furthermore, the vibrational and rotational transition frequencies of macromolecules, the phonon frequencies of condensed matter, and the response frequencies of charge carriers in certain semiconductor materials all fall within the mid- and far-infrared bands.

[0003] The mid- and far-infrared wavelengths lie at the transition stage between traditional microwave electronics and visible and near-infrared photonics. This wavelength range exhibits unique properties that preclude direct application of existing high-sensitivity detection technologies for microwaves, visible light, or near-infrared light. Currently, detection of mid- and far-infrared wavelengths is primarily achieved using thermal sensors, such as bolometers and pyroelectric detectors, or semiconductor photosensitive devices designed for the corresponding wavelengths, such as PbS, HgCdTe, InAsSb, and InAs. However, both direct detection devices in the mid- and far-infrared wavelengths present inherent challenges. While thermal sensors are inherently inexpensive, their low sensitivity severely limits their application. While semiconductor detectors can achieve higher sensitivity, they exhibit high noise levels at room temperature and require multi-stage thermoelectric coolers to operate at ultra-low temperatures. Consequently, mid- and far-infrared semiconductor detection systems are often bulky and require complex cooling systems, making them difficult to operate out of the box and significantly increasing their cost.

[0004] Therefore, how to design a mid- and far-infrared detection device with high sensitivity at room temperature becomes a technical problem that needs to be solved. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art or related art, and provides a mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity. The system not only achieves highly sensitive detection of mid- and far-infrared light intensity at room temperature, but also has the advantages of high integration and small size.

[0006] The present invention is achieved through the following technical solutions: a mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity, comprising: a whispering gallery mode microcavity portion, provided with a whispering gallery microcavity structure for receiving mid- and far-infrared light to be measured, the surface of the whispering gallery microcavity structure being coated with a mid- and far-infrared light absorbing material; a laser light source portion, provided with a laser and an electro-optical phase modulator, connected to the whispering gallery mode microcavity portion via an optical fiber, for emitting detection light; a photoelectric detection portion, provided with a photodetector and a mixer, the input side of the photodetector being connected to the whispering gallery mode microcavity portion via an optical fiber, the output side of the photodetector being electrically connected to the mixer, for detecting light signals in the whispering gallery mode microcavity; and a signal generating portion, provided with a signal generator, respectively connected to the laser light source portion and the photoelectric detection portion, for generating a modulated electrical signal, one modulated electrical signal driving the electro-optical phase modulator, and the other modulated electrical signal being sent to the mixer, so that the mixer provides a voltage signal to a voltmeter.

[0007] In this technical solution, laser light emitted by the laser light source passes through the whispering gallery mode microcavity and is then transmitted to the photodetector. The laser light is coupled into and out of the waveguide within the whispering gallery mode microcavity via a lensed fiber. The on-chip waveguide and ring microcavity are coupled via the evanescent field. The sinusoidal modulated signal generated by the signal generator is split into two paths: one drives an electro-optical phase modulator, and the other is mixed with the electrical signal from the photodetector in a mixer. The resulting electrical signal can be measured using a voltmeter. The whispering gallery microcavity is a miniature optical resonator that uses total internal reflection to confine the light field within a very small mode volume. Resonance between the light wave and the whispering gallery microcavity requires that the optical path length of the cavity mode be an integer multiple of the wavelength. Due to the extremely short wavelength of light, even small changes in the optical path length can significantly alter the microcavity's resonant state. Thanks to the ultra-high sensitivity of the cavity's optical resonance to the optical frequency and the ultra-high frequency of the light wave, highly sensitive detection of mid- and far-infrared light intensity at room temperature is achieved. Essentially, changes in the external environment cause changes in the optical path length or quality factor (Q value) of the microcavity mode, thereby interpreting the detection quantity through the resonant state of light and the microcavity.

[0008] According to the mid- and far-infrared broadband detection system based on whispering gallery mode microcavity provided by the present invention, preferably, the waveguide material of the whispering gallery microcavity structure is silicon, and the mid- and far-infrared absorption material is polydimethylsiloxane (PDMS).

[0009] In this technical solution, the whispering gallery microcavity structure is made by an etching process, and the preferred etching material is a silicon-on-insulator (SOI) wafer on an insulating substrate. The whispering gallery microcavity structure uses the SOI wafer as a substrate, and the etching process is mature and easy to prepare with existing technical means; the waveguide coupling integrated on the chip greatly improves the stability of the cavity light coupling, has good robustness, and the detection results are not easily affected by vibrations in the external environment. PDMS has a strong absorption effect on mid- and far-infrared light in a wide spectrum range, and can achieve wide-spectrum detection; PDMS can be applied by spin coating, and the coating thickness can be more accurately controlled by adjusting the speed and running time of the rotator. The present invention preferably uses a whispering gallery mode silicon ring cavity coated with PDMS on the chip as a thermal element, which has higher sensitivity than traditional mid- and far-infrared thermal element detection solutions and can operate at room temperature.

[0010] PDMS material has a high absorptivity in the mid- and far-infrared bands, converting mid- and far-infrared light energy into thermal energy. However, its own thermo-optic coefficient is negative. When coated on a common silica microsphere cavity with a positive thermo-optic coefficient, not only is the coating thickness difficult to control, making on-chip integration difficult, but the similar refractive indices of the two materials will cause the energy of the intracavity light mode to be distributed simultaneously in both materials. In this case, the sensitivity of the cavity mode to temperature is determined by the thermo-optic coefficients of the two materials. The opposite signs of the thermo-optic coefficients of the two materials will reduce thermal sensitivity, and the high absorption coefficient of PDMS will also significantly affect the Q value of the cavity mode, thereby reducing the sensitivity to mid- and far-infrared light detection. In addition, in traditional microcavity detection systems, it is often necessary to scan the output frequency of the pump laser and detect the changes in the cavity light resonant state by the changes in the transmission spectrum to obtain the measured value. This undoubtedly increases the complexity of the system and requires algorithmic processing of the directly obtained data, making it difficult to do without the assistance of a computing system. The present invention utilizes the PDH (Pound-Drever-Hall) technology used in laser frequency stabilization to achieve direct readout of the mid- and far-infrared light power to be measured.

[0011] According to the mid- and far-infrared light broadband detection system based on the whispering gallery mode microcavity provided by the present invention, preferably, the whispering gallery mode microcavity portion further includes: an optical filter arranged corresponding to the mid- and far-infrared light to be measured; and a focusing lens arranged on the lower side of the optical filter to focus the mid- and far-infrared light to be measured into the whispering gallery microcavity structure.

[0012] According to the mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity provided by the present invention, preferably, the laser light source unit further includes: a light polarization controller disposed between the laser and the electro-optical phase modulator.

[0013] According to the mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity provided by the present invention, preferably, the signal generating unit further includes: a phase shifter provided between the signal generator and the mixer.

[0014] According to the mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity provided by the present invention, preferably, the photoelectric detection unit further includes: a bandpass filter arranged between the photoelectric detector and the mixer; and a low-pass filter arranged between the mixer and the voltmeter.

[0015] According to the mid- and far-infrared light broadband detection system based on the whispering gallery mode microcavity provided by the present invention, preferably, the whispering gallery microcavity structure is designed as a square silicon waveguide with a cross-sectional size of 1×1 μm and a ring cavity diameter of 30 to 100 μm; the coating thickness of polydimethylsiloxane is 2.5 μm.

[0016] According to the mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity provided by the present invention, preferably, the laser is a narrow-linewidth laser, the output light is near-infrared light, the output wavelength includes the 1550nm band, the single-frequency output, and the laser linewidth is less than 10MHz.

[0017] In this technical solution, taking the wavelength of light of 12.5μm as an example, the refractive index of silicon is about 3.47, and that of PDMS is 1.68. The difference in the refractive index between the two (the larger the difference, the easier it is to meet the total reflection condition of light) ensures that the cavity mode energy is rarely distributed in the PDMS. After finite element simulation analysis, when the pump light is 1550nm, the 1×1μm silicon waveguide coated with PDMS, the proportion of fundamental mode energy in PDMS is about 0.2%. Therefore, it can be considered that the influence of PDMS on the Q value and resonance conditions of the cavity mode is almost negligible, and the negative thermo-optic coefficient of PDMS will not reduce the sensitivity of the detection system. The extremely short wavelength of the light wave and the extremely high sensitivity of the cavity light resonance condition make the detection sensitivity of the present invention to mid- and far-infrared light higher than that of traditional thermal detection devices. The high thermo-optic coefficient of the silicon material itself can achieve a thermal detection sensitivity far stronger than that of traditional silica microcavities.

[0018] According to the mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity provided by the present invention, preferably, the photodetector is an indium gallium arsenide (InGaAs) photodetector, and the operating band is the near-infrared light band.

[0019] According to the mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity provided by the present invention, preferably, the modulated electrical signal output by the signal generator is a sinusoidal modulation signal, and the modulation frequency is greater than the linewidth of the microcavity mode.

[0020] In this technical solution, the present invention adopts the PDH technology in laser frequency stabilization, and with the help of electro-optical phase modulation and circuit signal processing, converts the Lorentz response of the cavity optical resonance transmittance to the detuning amount into an approximately linear response, so that the infrared light intensity can be directly read through the reading of the voltmeter.

[0021] The beneficial effects achieved by the present invention include at least the following: In traditional whispering gallery microcavity sensing schemes, measuring changes in resonance conditions often requires scanning the pump wavelength to obtain the transmission spectrum of the microcavity mode, and it is impossible to directly obtain the value to be measured. The present invention adopts the PDH (Pound-Drever-Hall) technology in laser frequency stabilization, and with the help of electro-optical phase modulation and circuit signal processing, the Lorentz response of the cavity light resonance transmittance to the detuning amount is converted into an approximate linear response, so that the infrared light intensity can be directly read out through the reading of the voltmeter, without relying on an additional computer system to perform algorithmic processing on the acquired data. A whispering gallery microcavity (silicon ring cavity) coated with PDMS (polydimethylsiloxane, Polydimethylsiloxane, PDMS) is used as a thermal element. Compared with traditional mid- and far-infrared thermal element detection schemes, it has higher sensitivity and can work at room temperature. The PDMS material has a high absorption rate in the mid- and far-infrared bands, which greatly improves the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity according to an embodiment of the present invention is shown.

[0023] Figure 2 A schematic cross-sectional view of a whispering gallery microcavity structure of a mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity according to an embodiment of the present invention is shown.

[0024] Figure 3 FIG. 4 shows a diagram of detection results according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limiting the present invention. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0027] like Figure 1 、 Figure 2 and Figure 3 As shown, the present invention provides a mid-to-far infrared light broadband detection system based on a whispering gallery mode microcavity, comprising: a narrow linewidth laser (1), an optical polarization controller (2), an electro-optical phase modulator (3), a whispering gallery mode microcavity chip (4), a photodetector (5), a mid-to-far infrared light radiation source to be measured (6), an optical filter (7), a focusing lens (8), a signal generator (9), a phase shifter (10), a voltmeter (11), a low-pass filter (12), a mixer (13), and a bandpass filter (14). The narrow linewidth laser (1), the optical polarization controller (2), the electro-optical phase modulator (3), the whispering gallery mode microcavity chip (4), and the photodetector (5) are sequentially connected together through optical fibers, wherein the laser light is coupled into and out of the microcavity chip via the lens optical fiber. The sinusoidal modulation signal generated by the signal generator (9) is divided into two paths. One path drives the electro-optical phase modulator (3), and the other path passes through the phase shifter (10) and is mixed with the electrical signal of the photodetector (5) that has passed through the bandpass filter (14) in the mixer (13). The electrical signal generated after the mixing passes through the low-pass filter (12) and is finally measured by the voltmeter (11). The infrared light emitted by the mid- and far-infrared radiation source (6) to be measured is obtained through the optical filter (7) to obtain the infrared light of the desired measurement band range. The optical microcavity is placed at the focus of the focusing lens (8).

[0028] For a whispering gallery microcavity, its resonant wavelength is related to the refractive index of the microcavity material, as shown in the following equation:

[0029] mλ=2πRn

[0030] In the above formula, m is a non-zero integer, λ is the resonant wavelength, R is the microcavity radius, and n is the equivalent refractive index of the microcavity mode. When the temperature of the cavity changes, the equivalent refractive index of the microcavity mode will also change due to the influence of the thermo-optical effect, causing the resonant wavelength, that is, the frequency of the resonant light wave, to change. Figure 3As shown in part (a) (the transmission spectrum of the microcavity resonance, the cavity light is in a critical coupling state, and when the cavity light is completely resonant, the transmittance is zero), when the microcavity and the wavelength of light completely satisfy the mathematical relationship of the above formula, the energy of the transmitted light of the microcavity is the lowest. Keeping the pump wavelength unchanged, the resonant wavelength shift caused by temperature will cause the intensity of the transmitted light to change, so that the intensity of the infrared light can be measured. In this scheme, the light emitted by the mid- and far-infrared radiation source to be measured passes through a filter to obtain the measurement band of interest, and the infrared light to be measured is focused on the microcavity through a focusing lens. The PDMS layer coated on the microcavity has a strong absorption of mid- and far-infrared light, thus generating heat, which causes the resonant wavelength to change, and ultimately leads to a change in the power of the transmitted light.

[0031] The system comprises a narrow-linewidth laser, a polarization controller, an electro-optical phase modulator, a whispering gallery mode microcavity chip, and a photodetector connected via optical fiber. The polarization controller controls the polarization state of the pump light, achieving efficient resonance in the corresponding microcavity mode, while the electro-optical phase modulator provides sidebands for PDH technology. Laser light is coupled into and out of the on-chip waveguide via a fiber lens. After efficient coupling is achieved, the positions of the fiber lens and the waveguide port are precisely fixed.

[0032] The response of the transmission spectrum of the microcavity to the frequency of light is Lorentzian. The same transmitted light intensity can correspond to two different infrared light intensities and cannot be read directly. Therefore, PDH technology is used to realize the direct readout of the infrared light intensity to be measured. The specific process is that the photodetector converts the received microcavity transmitted light signal into an electrical signal, filters out the noise through a bandpass filter, and then mixes it with the sinusoidal signal generated by the signal generator. Among them, the phase shifter is used to adjust the phase difference between the two mixed electrical signals to achieve selective acquisition of the real part or imaginary part of the PDH error signal. The mixed electrical signal passes through a low-pass filter and is received by a voltmeter, thus realizing an approximate linear response relationship between the electrical signal and the infrared light intensity to be measured. The intensity of the mid- and far-infrared light can be directly read according to the voltage value, such as Figure 3 Part (b) shows the corresponding voltmeter measurement results after circuit processing. Each point corresponds to a different incident infrared light power, and the power difference between two adjacent points is 10μW. The simulation parameters for this detection result are set as the PDMS layer thickness of 2.5μm, the ring cavity waveguide of 1×1μm, the diameter of 50μm, and the intrinsic Q value of the microcavity of 1×10 5 The wavelength of the pump laser injected into the microcavity is 1550nm.

[0033] According to the above embodiment, preferably, the whispering gallery mode micro-ring cavity is preferably designed as a square silicon waveguide with a cross-sectional size of 1×1 μm and a ring cavity diameter of 30 to 100 μm. The mid- and far-infrared absorption material is covered on the chip surface by spin coating. The preferred material of the micro-cavity is PDMS, and the coating thickness is 2.5 μm.

[0034] According to the above embodiment, the microcavity chip is preferably fabricated using electron beam lithography and etching processes. The chip material is preferably an SOI wafer with an oxide layer thickness of 2 μm. The mask structure is written into the photoresist coated on the SOI wafer by electron beam lithography, and the silicon waveguide ring cavity is fabricated on the chip by dry etching.

[0035] According to the above embodiment, preferably, the output light of the narrow linewidth laser (1) is near-infrared light, the output wavelength is in the 1550nm band, single-frequency output, and the linewidth of the laser is less than 10MHz.

[0036] According to the above embodiment, the working band of the photodetector (5) is the near-infrared light band, and is preferably an indium gallium arsenide (InGaAs) detector.

[0037] According to the above embodiment, preferably, the modulation signal output by the signal generator (9) is a sine wave, and the modulation frequency is greater than the line width of the microcavity mode.

[0038] According to another embodiment of the present invention, a method for preparing a whispering gallery silicon ring cavity coated with a PDMS infrared light absorption layer is provided. A standard SOI wafer is used as a substrate, and an electron beam exposure and reactive ion etching process are used to prepare an on-chip integrated whispering gallery microcavity. The main steps include:

[0039] (1) Cleaning the SOI wafer. Contaminants on the surface of the material will significantly reduce the Q value of the microcavity, so it is necessary to ensure that the SOI wafer is sufficiently clean. Immerse the SOI wafer in acetone, ethanol, and deionized water in sequence, place it in an ultrasonic cleaner, and clean it in each solution for 20 minutes. Finally, blow it dry with a clean nitrogen gun.

[0040] (2) Spin-coat the photoresist. Use ZEP520A as the photoresist model. Use a pipette to drop the photoresist onto the SOI wafer and use the spin coating method to evenly cover the SOI wafer with the photoresist. Set the spin coater speed to 4000 rpm, the acceleration to 4000 rpm, and the spin coating time to 120 seconds. After the coating is completed, heat the chip on a heating table at 180°C for half an hour to allow the solvent in the photoresist to escape slowly and fully.

[0041] (3) Electron beam exposure. Place the SOI wafer with photoresist on the surface on the base of the electron beam exposure machine. Adjust the focus and astigmatism, and write the pattern structure on the mask into the photoresist through electron beam exposure. The parameters of the electron beam exposure machine are set as follows: acceleration voltage 30kV, aperture 15μm, beam current 55Pa, and electron beam dose factor 1.2. After the exposure is completed, place the chip in the developer for 60 seconds.

[0042] (4) Ion etching. The purpose of etching is to transfer the structure in the photoresist to the chip. For silicon etching, sulfur hexafluoride (SF6) is used, which can react chemically with silicon to produce volatile silicon tetrafluoride (SiF4). At the same time, the etching chamber is filled with trifluoromethane to protect the side walls. The specific parameters of the etching process are set as follows: gas pressure 15mTorr, RF power 300W, SF6 and trifluoromethane flow rates of 5 and 50sccm respectively, and etching time 15 minutes. After etching is completed, the chip is placed in the degumming solution, placed on a heating table, the temperature is set to 80℃, heated for 24 hours, and finally cleaned with acetone, alcohol, and deionized water.

[0043] (5) Spin coating PDMS and curing. The PDMS used is model Dow Corning DC184, and the basic components and curing agent are fully mixed in a mass ratio of 7:1. Use a dropper to absorb the uncured PDMS glue and drop it on the prepared microcavity chip. The thickness of the final PDMS layer is controlled by adjusting the speed of the rotary glue machine. The speed is set between 1000 and 6000 rpm and the spin coating time is 120 seconds. After spin coating, the chip is sealed and placed in a blast drying oven with the temperature set at 120℃. Blast dry for 6 hours and then take it out.

[0044] The cross-sectional structure of the silicon microcavity with PDMS layer finally fabricated is as follows: Figure 2 The resonant state of this microcavity is almost solely determined by the silicon material, resulting in a high Q value and red light detection sensitivity. Figure 2 The depth of the color in the middle represents the temperature. The temperature distribution is obtained through finite element simulation. The specific setting is that a plane wave with a wavelength of 12.5μm and an electric field strength of about 1500V / m is incident on the chip. The PDMS layer thickness is 1μm, the ring cavity waveguide is 1×1μm, and the diameter is 50μm. The material's absorption of electromagnetic waves is used as a heat source, and the temperature distribution is obtained under steady-state conditions.

[0045] The mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity provided by the present invention converts mid- and far-infrared light into heat energy through the absorption of PDMS. An on-chip integrated silicon ring cavity (whispering gallery microcavity structure) then converts the heat into a change in the refractive index of a silicon waveguide, thereby causing a change in the resonant state of the optical cavity. A photodetector is used to convert the optical signal representing the resonant state of the cavity light into an electrical signal. The extremely high sensitivity of the cavity light resonance condition is utilized to accurately detect the intensity of the infrared light. Finally, with the aid of a circuit system, the Lorentz response of the cavity light resonance transmittance to the detuning amount is converted into an approximately linear response, thereby enabling direct readout of the infrared light intensity.

[0046] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity, characterized in that: include: The whispering gallery mode microcavity portion is provided with a whispering gallery microcavity structure for receiving the mid- and far-infrared light to be measured, wherein the surface of the whispering gallery microcavity structure is coated with a mid- and far-infrared light absorbing material; a laser light source unit, provided with a laser and an electro-optical phase modulator, connected to the whispering gallery mode microcavity unit via an optical fiber, for emitting probe light; a photoelectric detection unit, comprising a photodetector and a mixer, wherein the input side of the photodetector is connected to the whispering gallery mode microcavity unit via an optical fiber, and the output side of the photodetector is electrically connected to the mixer, for detecting the optical signal in the whispering gallery mode microcavity; The signal generating unit is provided with a signal generator, which is respectively connected to the laser light source unit and the photoelectric detection unit, and is used to generate a modulated electrical signal. One modulated electrical signal drives the electro-optical phase modulator, and the other modulated electrical signal is sent to the mixer so that the mixer provides a voltage signal to the voltmeter.

2. The mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity according to claim 1 is characterized in that: The waveguide material of the whispering gallery microcavity structure is silicon, and the mid- and far-infrared light absorption material is polydimethylsiloxane.

3. The mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity according to claim 1 is characterized in that: The whispering gallery mode microcavity portion further includes: An optical filter, configured to correspond to the mid- and far-infrared light to be measured; A focusing lens is provided on the lower side of the optical filter to focus the mid- and far-infrared light to be measured into the whispering gallery microcavity structure.

4. The mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity according to claim 1, characterized in that: The laser light source unit further includes: The optical polarization controller is arranged between the laser and the electro-optical phase modulator.

5. The mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity according to claim 1 is characterized in that: The signal generating unit further includes: A phase shifter is arranged between the signal generator and the mixer.

6. The mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity according to claim 1, characterized in that: The photoelectric detection unit further includes: a bandpass filter, disposed between the photodetector and the mixer; A low-pass filter is provided between the mixer and the voltmeter.

7. The mid- and far-infrared light broadband detection system based on whispering gallery mode microcavity according to claim 2, characterized in that: The whispering gallery microcavity structure is designed as a square silicon waveguide with a cross-sectional size of 1×1 μm and a ring cavity diameter of 30 to 100 μm; the coating thickness of the polydimethylsiloxane is 2.5 μm.

8. The mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity according to any one of claims 1 to 7, characterized in that: The laser is a narrow linewidth laser, the output light is near-infrared light, the output wavelength includes the 1550nm band, single-frequency output, and the linewidth of the laser is less than 10MHz.

9. The mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity according to any one of claims 1 to 7, characterized in that: The photoelectric detector is an indium gallium arsenide photoelectric detector, and its operating band is the near-infrared light band.

10. The mid- and far-infrared light broadband detection system based on a whispering gallery mode microcavity according to any one of claims 1 to 7, characterized in that: The modulated electrical signal output by the signal generator is a sinusoidal wave modulation signal, and the modulation frequency is greater than the line width of the microcavity mode.

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