CN115265773A - Mid- and far-infrared broadband detection system based on whispering gallery mode microcavity - Google Patents

Abstract

The invention provides a mid- and far-infrared light wide-spectrum detection system based on a whispering gallery mode microcavity, and relates to the technical field of infrared detection. Material; laser light source part, used for emitting detection light; photoelectric detection part, used to detect the optical signal in the whispering gallery mode microcavity; signal generation part, used to support the mixer to provide voltage signal to the voltmeter. The 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 micro-cavity, and then the heat is conducted into the micro-cavity waveguide by the absorption layer, causing the temperature of the waveguide to change. Under the action, the equivalent refractive index of the microcavity mode changes, and the resonant frequency shifts, so that the transmitted optical power of the microcavity changes, and the optical power is converted into an electrical signal by the photodetector, which realizes the measurement of the mid- and far-infrared light intensity at room temperature. Highly sensitive detection.

Description

Broad-spectrum detection system for mid- and far-infrared light based on whispering gallery mode microcavity

technical field

The invention relates to the technical field of infrared detection, in particular to a mid-to-far infrared wide-spectrum detection system based on a whispering gallery mode microcavity.

Background technique

Compared with microwaves, visible and near-infrared light waves, electromagnetic waves in the mid-to-far infrared band, especially the terahertz band, have not been fully researched and developed for a long time due to the lack of high-performance radiation sources and high-sensitivity effective detection methods. use. However, the mid-to-far infrared band has very important application prospects in the fields of public security, wireless communication, biological effects, biomedical imaging, and information technology. For example, the spontaneous radiation of the human body is in the mid-to-far infrared band. In addition to being used to measure the temperature of the human body, the rich information contained in its spectrum is expected to reflect the health and psychological state of the human body. In addition, the transition frequency of vibration and rotation of macromolecules, the phonon frequency of condensed matter, and the response frequency of carriers in some semiconductor materials are all in the mid-to-far infrared band.

The mid-to-far infrared band is located in the transition stage from microwave electronics to visible and near-infrared photonics in traditional research. This band has some special properties and cannot directly use the existing high-sensitivity detection technology of microwave or visible and near-infrared light. At present, the detection of mid- and far-infrared waves is mainly realized by thermal sensitive elements, such as bolometers, pyroelectric detectors, or semiconductor photosensitive elements of corresponding wavelength bands, such as PbS, HgCdTe, InAsSb, InAs, etc. However, there are some unavoidable problems in these two kinds of direct detection devices in the middle and far infrared bands. For the thermal element, although its own price is cheap, its lower sensitivity strictly limits its application range. Although semiconductor detectors can achieve high sensitivity, they have a high noise level at room temperature and must use multi-stage thermoelectric coolers to lower the temperature to work at ultra-low temperatures, resulting in mid-to-far infrared semiconductor detection systems. It is bulky and contains a complex refrigeration system, which cannot be used immediately after startup, and the cost is also greatly increased.

Therefore, how to design a mid-to-far infrared detection device with high sensitivity at room temperature has become a technical problem to be solved.

Contents of the invention

The present invention aims to solve at least one of the technical problems in the above-mentioned prior art or related technologies, and provides a mid-far infrared light broadband detection system based on a whispering gallery mode microcavity, which not only realizes the detection of mid-far infrared light intensity at room temperature High sensitivity detection, also has the advantages of high integration, small size and so on.

The present invention is realized through the following technical solutions: a mid-to-far infrared wide-spectrum detection system based on a whispering gallery mode microcavity, comprising: a whispering gallery mode microcavity part, which is provided with a whispering gallery microcavity structure for receiving In the mid-to-far infrared light, the surface of the whispering gallery microcavity structure is coated with mid-to-far infrared light absorbing materials; the laser light source part is equipped with a laser and an electro-optical phase modulator, which is connected to the whispering gallery mode microcavity part through an optical fiber to emit detection light; The detection part is provided with a photodetector and a mixer. The input side of the photodetector is connected to the microcavity of the whispering gallery mode through an optical fiber, and the output side of the photodetector is electrically connected to the mixer for detecting the microcavity of the whispering gallery mode. The optical signal in the cavity; the signal generating part is equipped with a signal generator, which is respectively connected to the laser light source part and the photoelectric detection part, and is used to generate a modulated electrical signal. One modulated electrical signal drives the electro-optic phase modulator, and the other modulated electrical signal is sent to mixer so that the mixer provides a voltage signal to the voltmeter.

In this technical solution, the laser light emitted by the laser light source part passes through the microcavity part of the whispering gallery mode and then is transmitted to the photodetection part, wherein the laser light is coupled into and out of the waveguide in the microcavity part of the microcavity part of the whispering gallery mode by a lens fiber, and the on-chip waveguide and The ring microcavities are coupled through the evanescent field. The sinusoidal modulation signal generated by the signal generation part is divided into two routes, one route drives the electro-optic phase modulator, and the other route is mixed with the electrical signal of the photodetector part in the mixer, and the electrical signal generated after mixing is convenient to be measured by a voltmeter. Measurement. Among them, the whispering gallery microcavity is a miniature optical resonator, which uses total internal reflection to confine the light field in a small mode volume. The resonance between the light wave and the whispering gallery microcavity must satisfy the relationship that the optical path length of the intracavity mode is an integer multiple of the light wavelength. Due to the extremely short wavelength of light, a very small change in the optical path length will affect a significant change in the resonant state of the microcavity. Thanks to the ultra-high sensitivity of the cavity optical resonance condition to the optical frequency and the ultra-high frequency of the light wave, the highly sensitive detection of the mid-to-far infrared light intensity at room temperature is realized. Essentially, changes in the external environment cause changes in the optical path length or quality factor (Q value) of the microcavity mode, so that the detection amount can be interpreted through the resonance state of the light and the microcavity.

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

In this technical scheme, the microcavity structure of the whispering gallery is manufactured by etching process, and the preferred etching material is silicon (Silicon-On-Insulator, SOI) sheet on the insulating substrate, and the microcavity structure of the whispering gallery uses the SOI sheet as the substrate , the etching process is mature, and it is easy to prepare with the existing technical means; the integrated waveguide coupling on the chip greatly improves the stability of the cavity optical coupling, has good robustness, and the detection results are not easily affected by the vibration of the external environment. PDMS has a strong absorption effect on mid- and far-infrared light in a wide spectrum range, and can realize wide-spectrum detection; PDMS can be coated by spin coating, and the thickness of the coating can be achieved by adjusting the rotation speed and running time of the spinner. Precise control. The present invention preferably adopts the whispering gallery mode silicon ring cavity coated with PDMS on the chip as the thermal sensor, which has higher sensitivity than the traditional mid-far infrared thermal sensor detection scheme and can work at room temperature.

PDMS material has a high absorption rate in the mid-to-far infrared band, which can convert the light energy of the mid-to-far infrared wave into heat energy. However, its own thermo-optic coefficient is negative. When it is coated on the common silica microsphere cavity with positive thermo-optic coefficient, not only the thickness of the coating is not easy to control, but also it is difficult to achieve on-chip integration. The refraction of the two materials is similar. The efficiency will make the energy of the optical mode in the cavity be distributed in the two materials at the same time, and the sensitivity of the cavity mode to temperature is determined by the thermo-optic coefficient of the two materials. The thermo-optic coefficients of the two materials with opposite signs will reduce the 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 the traditional microcavity detection system, it is often necessary to scan the output frequency of the pump laser, and use the change of the transmission spectrum to detect the change of the optical resonance state of the cavity to obtain the measurement, which undoubtedly increases the complexity of the system. Algorithmic processing of directly acquired data is required, so it is difficult to do without the assistance of computing systems. The invention utilizes the PDH (Pound-Drever-Hall) technology used in laser frequency stabilization, and realizes the direct readout of the middle and far infrared light power to be measured.

According to the mid-to-far infrared wide-spectrum detection system based on the whispering gallery mode microcavity provided by the present invention, preferably, the whispering gallery mode microcavity part further includes: an optical filter, which is set corresponding to the mid-to-far infrared light to be measured; a focusing lens, which is located at The lower side of the optical filter focuses the mid-to-far infrared light to be measured in the microcavity structure of the whispering gallery.

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

According to the mid-to-far infrared broad-spectrum detection system based on the whispering gallery mode microcavity provided by the present invention, preferably, the signal generating part further includes: a phase shifter arranged between the signal generator and the mixer.

According to the mid-to-far infrared wide-spectrum detection system based on the whispering gallery mode microcavity provided by the present invention, preferably, the photodetection part further includes: a band-pass filter arranged between the photodetector and the mixer; a low-pass filter , set between the mixer and the voltmeter.

According to the mid-to-far infrared broadband detection system based on the whispering gallery mode microcavity provided by the present invention, preferably, the structure of the whispering gallery microcavity 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 dimethylsiloxane was 2.5 μm.

According to the mid-to-far infrared wide-spectrum detection system based on the 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 a 1550nm band, single-frequency output, and the line of the laser The width is less than 10MHz.

In this technical solution, taking the light wavelength of 12.5 μm as an example, the refractive index of silicon is about 3.47, and that of PDMS is 1.68. Mode energy can rarely be distributed in PDMS. After finite element method 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 one thousandth. two. Therefore, it can be considered that the influence of PDMS on the Q value of the cavity mode and the resonance conditions 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 optical resonance condition make the detection sensitivity of the present invention to the middle and far infrared light higher than that of the traditional heat-sensitive detection device, and the high thermo-optic coefficient of the silicon material itself can realize far stronger Thermal detection sensitivity of silicon oxide microcavities.

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

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

In this technical solution, the present invention adopts PDH technology in laser frequency stabilization, and by means of electro-optical phase modulation and circuit signal processing, the Lorentz response of the cavity optical resonance transmittance to the detuning amount is converted into an approximate linear response, so that it can pass The indication of the voltmeter directly reads the infrared light intensity.

The beneficial effects obtained by the present invention include at least: in the traditional whispering gallery microcavity sensing scheme, the measurement of the change of the resonance condition often needs to scan the pump wavelength to obtain the transmission spectrum of the microcavity mode, and the value to be measured cannot be obtained directly. The present invention uses a laser The PDH (Pound-Drever-Hall) technology in frequency stabilization, with the help of electro-optic phase modulation and circuit signal processing, converts the Lorentz response of the cavity optical resonance transmittance to the detuning amount into an approximate linear response, so that the voltmeter can The display reads out the infrared light intensity directly, and does not rely on an additional computer system to perform algorithmic processing on the acquired data. The whispering gallery microcavity (silicon ring cavity) coated with PDMS (Polydimethylsiloxane, PDMS) is used as the thermal element, which has higher sensitivity than the traditional mid-far infrared thermal element detection scheme , and can work at room temperature. PDMS material has a high absorption rate in the mid-to-far infrared band, which greatly improves the detection accuracy.

Description of drawings

Fig. 1 shows a schematic structural diagram of a mid-far infrared light broadband detection system based on a whispering gallery mode microcavity according to an embodiment of the present invention.

Fig. 2 shows a schematic cross-sectional view of a whispering gallery microcavity structure of a mid-far infrared light broadband detection system based on a whispering gallery mode microcavity according to an embodiment of the present invention.

Fig. 3 shows a graph of detection results according to an embodiment of the present invention.

Detailed ways

In order to understand the above-mentioned purpose, features and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", " The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner" and "outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and Simplified descriptions, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention based on specific situations.

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

For a whispering gallery microcavity, its resonant wavelength is related to the refractive index of the microcavity material, as follows:

mλ=2πRn

In the above formula, m is a non-zero integer, λ is the resonance wavelength, R is the radius of the microcavity, and n is the equivalent refractive index of the microcavity mode. When the temperature of the cavity changes, due to the thermo-optic effect, the equivalent refractive index of the microcavity mode will also change, thereby causing the resonant wavelength, that is, the frequency of the resonant light wave to change. As shown in part (a) of Figure 3 (the transmission spectrum of the microcavity resonance, the cavity light is in a critical coupling state, when the cavity light is fully resonant, the transmittance is zero), when the microcavity and light wavelength fully satisfy the above formula In the mathematical relationship, the transmitted light energy of the microcavity is the lowest, keeping the pump wavelength unchanged, the temperature-induced resonant wavelength shift will change the transmitted light intensity, so that the intensity of infrared light can be measured. In the scheme, the light emitted by the medium-to-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 concentrated on the microcavity through a focusing lens. The PDMS layer coated on the microcavity has a strong absorption of mid- and far-infrared light, so heat is generated, which causes the resonance wavelength to change, and finally leads to the change of the transmitted light power.

In the system, a narrow-linewidth laser, an optical polarization controller, an electro-optic phase modulator, a whispering gallery mode microcavity chip, and a photodetector are connected through optical fibers. The optical polarization controller is used to control the polarization state of the pump light to achieve high-efficiency resonance corresponding to the microcavity mode, and the electro-optical phase modulator is used to provide sidebands for PDH technology. The laser light is coupled into and out of the waveguide on the chip through the fiber lens. After the fiber lens and the waveguide port are coupled efficiently, the positions of the two are precisely fixed.

The response of the transmission spectrum of the microcavity to the light frequency is Lorentzian, and the same transmitted light intensity can correspond to two different infrared light intensities, which cannot be read directly. Therefore, the 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 band-pass filter, and mixes it with the sinusoidal signal generated by the signal generator. Wherein, the phase shifter is used to adjust the phase difference of the two mixed frequency electrical signals, so as to selectively obtain the real part or the imaginary part of the PDH error signal. The electrical signal after frequency mixing is accepted by the voltmeter after passing through the low-pass filter, so that the approximate linear response relationship between the electrical signal and the intensity of the infrared light to be measured is realized, and the intensity of the mid-to-far infrared light can be read directly according to the voltage value, as shown in the figure Part (b) of 3 shows: the measurement results of the corresponding voltmeter obtained after circuit processing, each point corresponds to a different incident infrared light power, and the power difference between two adjacent points is 10 μW. The simulation parameters of the detection results are set as the thickness of the PDMS layer is 2.5 μm, the ring cavity waveguide is 1×1 μm, the diameter is 50 μm, the intrinsic Q value of the microcavity is 1×10 ⁵ , and the wavelength of the pump laser injected into the microcavity is 1550nm.

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 preferred material of the cavity is PDMS, and the coating thickness is 2.5 μm.

According to the above-mentioned embodiment, preferably, the microcavity chip is manufactured by electron beam exposure and etching process, the chip manufacturing material is preferably SOI sheet, and the thickness of the oxide layer is 2 μm. The structure of the mask plate is written into the photoresist coated on the SOI chip by electron beam exposure, and the silicon waveguide ring cavity on the chip is produced by dry etching.

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

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

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.

According to another embodiment of the present invention, there is also provided a method for preparing a whispering gallery silicon ring cavity coated with a PDMS infrared light absorbing layer, using a standard SOI sheet as a substrate, and using electron beam exposure and reactive ion etching processes Prepare the whispering gallery microcavity integrated on the chip, the main steps include:

(1) Cleaning of SOI sheet. 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 sheet is clean enough. The SOI sheet was immersed in acetone, ethanol, and deionized water in sequence, and placed in an ultrasonic cleaner. Each solution was cleaned for 20 minutes, and finally dried with a clean nitrogen gun.

(2) Spin-coat photoresist. The model of the photoresist is ZEP520A, and the photoresist is dropped onto the SOI sheet with a straw, and the photoresist is evenly covered on the SOI sheet by the spin coating method. The rotational speed of the rotary coater was set at 4000 rpm, the acceleration was 4000 rpm, and the spin coating time was 120 seconds. After homogenization, heat the chip at 180°C on a heating platform for half an hour to allow the solvent in the photoresist to escape slowly and fully.

(3) Electron beam exposure. Put the SOI sheet with photoresist on the surface on the base of the electron beam exposure machine, adjust the focal length and astigmatism, and write the pattern structure on the mask plate into the photoresist by means of electron beam exposure. The parameters of the electron beam exposure machine are set as follows: accelerating voltage 30Kv, aperture 15μm, beam current 55Pa, electron beam dose factor 1.2. After the exposure, the chip was placed in the developer solution for 60 seconds.

(4) Ion etching. The purpose of etching is to transfer the structure in the photoresist to the chip. For the etching of silicon, sulfur hexafluoride (SF ₆ ) is used, which can chemically react with silicon to produce volatile silicon tetrafluoride ( SiF ₄ ), while filling the etching chamber with trifluoromethane to protect the sidewall. The specific parameters in the etching process are set as follows: gas pressure 15mTorr, radio frequency power 300W, flow rates of SF ₆ and trifluoromethane respectively 5 and 50 sccm, and etching time 15 minutes. After the etching is completed, put the chip into the glue remover, place it on a heating platform, set the temperature at 80°C, heat it for 24 hours, and finally clean it with acetone, alcohol, and deionized water.

(5) Spin coating PDMS and curing. The PDMS model is Dow Corning DC184, and the basic components and curing agent are fully mixed according to the mass ratio of 7:1. Use a dropper to draw uncured PDMS glue and drop it on the prepared microcavity chip. The thickness of the final PDMS layer was controlled by adjusting the rotational speed of the rotary coater, the rotational speed was set at 1000 to 6000 rpm, and the spin coating time was 120 seconds. After the spin coating is completed, the chip is sealed and placed in a blast drying oven with a set temperature of 120° C., and is taken out after blast drying for 6 hours.

The cross-sectional structure of the finally fabricated silicon microcavity with PDMS layer is shown in Fig. 2 . The resonance state of the microcavity is almost only determined by the silicon material, which can have a high Q value and red light detection sensitivity. The depth of the color in Figure 2 represents the temperature. The temperature distribution is simulated by the finite element method. The specific setting is that a plane wave with a wavelength of 12.5 μm and an electric field strength of about 1500 V/m is incident on the chip, and the thickness of the PDMS layer is is 1 μm, the ring cavity waveguide is 1×1 μm, and the diameter is 50 μm. The absorption of electromagnetic waves by the material is used as a heat source, and the temperature distribution is obtained in a steady state.

The mid-to-far infrared wide-spectrum detection system based on the whispering gallery mode microcavity provided by the present invention converts the mid-to-far infrared light into thermal energy through the absorption of PDMS, and then converts the heat into silicon with an on-chip integrated silicon ring cavity (whispering gallery microcavity structure). Changes in the refractive index of the waveguide lead to changes in the resonant state of the optical cavity. Use a photodetector to convert the optical signal that characterizes the optical resonant state of the cavity into an electrical signal, and use the extremely high sensitivity of the resonant condition of the cavity to accurately detect the intensity of infrared light. , and finally with the help of the circuit system, the Lorentz response of the cavity optical resonance transmittance to the detuning amount is converted into an approximate linear response, thereby realizing the direct readout of the infrared light intensity.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A mid-far infrared wide-spectrum detection system based on whispering gallery mode microcavity is characterized by comprising:

the echo wall mode microcavity part is provided with an echo wall microcavity structure and is used for receiving medium and far infrared light to be detected, and a medium and far infrared light absorbing material is coated on the surface of the echo wall microcavity structure;

the laser light source part is provided with a laser and an electro-optic phase modulator, is connected with the whispering gallery mode micro-cavity part through an optical fiber and is used for emitting probe light;

the photoelectric detection part is provided with a photoelectric detector and a mixer, the input side of the photoelectric detector is connected with the whispering gallery mode microcavity part through an optical fiber, and the output side of the photoelectric detector is electrically connected with the mixer and used for detecting an optical signal in the whispering gallery mode microcavity;

the signal generation portion is equipped with signal generator, connects respectively laser light source portion with photoelectric detection portion for produce the modulation signal of telecommunication, the drive of modulation signal of telecommunication of the same kind the electro-optic phase modulator, another way modulation signal of telecommunication send to the mixer, so that the mixer provides voltage signal to the voltmeter.

2. The whispering gallery mode microcavity-based mid-far infrared broadband detection system as claimed in claim 1, wherein the waveguide material of the whispering gallery microcavity structure is silicon, and the mid-far infrared absorbing material is polydimethylsiloxane.

3. The whispering gallery mode microcavity-based mid-to-far infrared broad spectrum detection system of claim 1, wherein the whispering gallery mode microcavity portion further comprises:

the optical filter is arranged corresponding to the mid-far infrared light to be detected;

and the focusing lens is arranged on the lower side of the optical filter and used for focusing the mid-infrared light to be detected in the echo wall micro-cavity structure.

4. The whispering gallery mode microcavity-based mid-to-far infrared broad spectrum detection system of claim 1, wherein the laser light source portion further comprises:

and the optical polarization controller is arranged between the laser and the electro-optical phase modulator.

5. The whispering gallery mode microcavity-based mid-far infrared broadband detection system of claim 1, wherein the signal generation section further comprises:

a phase shifter disposed between the signal generator and the mixer.

6. The whispering gallery mode microcavity-based mid-far infrared broadband detection system of claim 1, wherein the photodetection portion further comprises:

a band-pass filter disposed between the photodetector and the mixer;

a low pass filter disposed between the mixer and the voltmeter.

7. The mid-far infrared broad spectrum detection system based on the whispering gallery mode microcavity is characterized in that the whispering gallery microcavity structure is designed as a square silicon waveguide with a cross-sectional dimension of 1 x 1 μm and a diameter of the ring cavity of 30-100 μm; the coating thickness of the polydimethylsiloxane was 2.5 μm.

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

9. The whispering gallery mode microcavity-based mid-to-far infrared broadband detection system of any one of claims 1 to 7, wherein the photodetector is an indium gallium arsenide photodetector, and the operating band is a near infrared band.

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

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