Narrow-linewidth millimeter wave terahertz spectrum measurement device and method based on Fabry-Perot interferometer

Abstract

The invention provides a narrow-linewidth millimeter wave terahertz spectrum measurement device and method based on a Fabry-Perot interferometer. The narrow-linewidth millimeter wave terahertz spectrum measurement device comprises the Fabry-Perot interferometer, a terahertz lens, a power detection device and a linewidth analysis device, a radiation signal of a radiation source to be measured passes through the terahertz lens and the Fabry-Perot interferometer to generate a focusing signal; the focusing signal is input to the power detection device for spectral analysis of the radiation signal, and the focusing signal is input to the line width analysis device for line width analysis of the radiation signal. The problems that in the prior art, the coverage range of millimeter wave and terahertz wave spectrum measurement power is small, the requirement for the environment is high, and narrow linewidth measurement of high-frequency-band radiation is difficult to carry out are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of spectrum measurement, and in particular to a narrow-linewidth millimeter-wave terahertz spectrum measurement device and method based on a Fabry-Perot interferometer. Background Art

[0002] Millimeter wave and terahertz bands are located between microwave and infrared bands of the electromagnetic spectrum, with a frequency range of approximately 30 GHz to 10 THz. They have unique properties, such as strong penetration, good directivity, and high bandwidth and spectral resolution, which make them have important application prospects in imaging, communication and sensing. The terahertz band (0.1 THz to 10 THz) has attracted widespread attention from the scientific and industrial communities because of its important potential in non-destructive testing, biomedical imaging, security inspection, communication and other fields.

[0003] In the development of millimeter wave and terahertz technology, the introduction of narrow linewidth radiation sources is particularly critical. Narrow linewidth radiation refers to electromagnetic radiation with extremely narrow spectrum width. It has the characteristics of high spectrum resolution, which enables more accurate acquisition of spectral characteristics and material information of substances in spectrum measurement and imaging applications. For example, in terahertz spectroscopy measurement, narrow linewidth radiation can more effectively distinguish the subtle features of different materials and improve the measurement accuracy of the system.

[0004] Common millimeter-wave terahertz radiation linewidth test methods include direct detection technology, harmonic mixing technology, photoelectric conversion detection technology, vector network analysis technology, etc. Direct detection technology uses a spectrum analyzer, which is simple, but is limited by the resolution of the spectrum analyzer and has certain requirements for the power of radiation; harmonic mixing technology uses nonlinear materials to generate harmonic frequencies of signals and measures the spectrum width of these harmonics, which is suitable for the measurement of ultra-narrow linewidth signals, but the system implementation is complex and has high requirements for the performance of nonlinear materials; photoelectric conversion detection technology converts high-frequency millimeter-wave or terahertz wave signals into optical signals and then measures them through optical detectors, but the photoelectric conversion efficiency is usually low, especially in the high frequency band (terahertz band), which may cause signal attenuation and noise problems, and the photoelectric components have high requirements for the environment; vector network analyzer technology usually requires additional frequency extension modules (such as external mixers) in the millimeter-wave terahertz band, the system cost is high and the operation is complex and costly, and the measurement accuracy of narrow linewidth radiation is limited. Summary of the invention

[0005] The present invention provides a narrow linewidth millimeter wave terahertz spectrum measurement device and method based on a Fabry-Perot interferometer, which is used to solve the problems in the prior art of small power coverage range of millimeter wave and terahertz wave spectrum measurement, high environmental requirements, and difficulty in performing narrow linewidth measurement of high-frequency band radiation.

[0006] The present invention provides a narrow linewidth millimeter-wave terahertz spectrum measuring device based on a Fabry-Perot interferometer, comprising: Fabry-Perot interferometer, terahertz lens, power detection device and linewidth analysis device; The radiation signal of the radiation source to be measured generates a focusing signal after passing through the terahertz lens and the Fabry-Perot interferometer; The focused signal is input into the power detection device to perform spectrum analysis of the radiation signal, and the focused signal is input into the line width analysis device to perform line width analysis of the radiation signal.

[0007] According to a narrow linewidth millimeter-wave terahertz spectrum measuring device based on a Fabry-Perot interferometer provided by the present invention, the terahertz lens comprises: a first terahertz lens and a second terahertz lens; The Fabry-Perot interferometer is arranged between the first terahertz lens and the second terahertz lens.

[0008] According to a narrow-linewidth millimeter-wave terahertz spectrum measuring device based on a Fabry-Perot interferometer provided by the present invention, the first terahertz lens receives a radiation signal emitted by a radiation source to be measured, and focuses the radiation signal into a parallel light beam through the first terahertz lens to generate a collimated terahertz signal.

[0009] According to a narrow linewidth millimeter-wave terahertz spectrum measuring device based on a Fabry-Perot interferometer provided by the present invention, the Fabry-Perot interferometer comprises: a first reflector and a second reflector; The first reflector is parallel to the second reflector, and the distance between the first reflector and the second reflector is adjustable; An optical resonant cavity is formed based on the first reflecting mirror, the second reflecting mirror and the spacing gap therebetween.

[0010] According to a narrow-linewidth millimeter-wave terahertz spectrum measuring device based on a Fabry-Perot interferometer provided by the present invention, the collimated terahertz signal enters the optical resonant cavity, undergoes multiple reflections and interferences between a first reflector and a second reflector to form a standing wave, and is emitted from the second reflector to generate an interference signal.

[0011] According to a narrow-linewidth millimeter-wave terahertz spectrum measuring device based on a Fabry-Perot interferometer provided by the present invention, the interference signal is focused by a second terahertz lens to generate a focusing signal.

[0012] According to a narrow-linewidth millimeter-wave terahertz spectrum measurement device based on a Fabry-Perot interferometer provided by the present invention, the focused signal enters a power detection device, and the signal strength is detected by the power detection device, and the spectrum information of the radiation signal is obtained after Fourier transformation.

[0013] According to a narrow linewidth millimeter-wave terahertz spectrum measurement device based on a Fabry-Perot interferometer provided by the present invention, the focused signal enters a linewidth analysis device for denoising, filtering and frequency domain transformation to complete preprocessing, and linewidth analysis is performed on the preprocessed focused signal.

[0014] The present invention also provides a method for measuring a narrow linewidth millimeter-wave terahertz spectrum based on a Fabry-Perot interferometer, comprising: The radiation signal emitted by the radiation source to be measured is injected into the first terahertz lens, and a collimated terahertz signal is generated through the first terahertz lens; The collimated terahertz signal is reflected and interfered multiple times in the optical resonant cavity to form a standing wave, which is emitted from the second reflector to generate an interference signal; The interference signal is focused by a second terahertz lens to generate a focusing signal; Based on the focused signal, spectrum analysis and linewidth analysis are performed through a power detection device and a linewidth analysis device.

[0015] According to a narrow-linewidth millimeter-wave terahertz spectrum measurement method based on a Fabry-Perot interferometer provided by the present invention, the cavity length of the optical resonant cavity is adjusted by changing the spacing between the first reflector and the second reflector in the optical resonant cavity, the amplitude of the incident collimated terahertz signal is enhanced, and an interference signal is obtained.

[0016] The present invention provides a narrow-linewidth millimeter-wave terahertz spectrum measurement device and method based on a Fabry-Perot interferometer, which improves the measurement accuracy of narrow-linewidth radiation in the millimeter-wave and terahertz frequency bands through the interference enhancement of the Fabry-Perot interferometer; can adapt to signals of different power levels, including low-power small signals, and expands the application scope of the measurement; reduces the dependence on the experimental environment, makes the measurement process simpler and reduces the cost; supports real-time adjustment and interaction through automated data acquisition and signal processing, and improves the flexibility and efficiency of the measurement; and provides an effective solution to the problems of low narrow-linewidth measurement accuracy and high requirements on radiation power and experimental environment in the prior art; improves the stability and reliability of the system through precise control and advanced signal processing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1It is a schematic structural diagram of a narrow-linewidth millimeter-wave terahertz spectrum measurement device based on a Fabry-Perot interferometer provided by the present invention.

[0019] Figure 2 The present invention provides a flow chart of a method for measuring a narrow-linewidth millimeter-wave terahertz spectrum based on a Fabry-Perot interferometer.

[0020] Figure numerals: 1: radiation source to be measured; 2: first terahertz lens; 3: first reflector; 4: second reflector; 5: second terahertz lens; 6: focusing signal; 7: power detection device; 8: line width analysis device. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The Fabry-Perot (FP) interferometer is an important optical system that uses two parallel mirrors with high reflectivity to form a stable standing wave field to select and enhance radiation of a specific wavelength. The FP interferometer has the advantages of simple structure, convenient tuning, and high spectral resolution, and can accurately measure the line width and frequency characteristics of radiation. In the millimeter wave and terahertz fields, FP interferometers are often used in combination with various detection technologies, such as direct detection, harmonic mixing, and photoelectric conversion, to achieve accurate analysis and measurement of radiation signals. Therefore, FP interferometers have broad application prospects in optical communications, spectral analysis, radar systems, and other fields.

[0023] The narrow-linewidth millimeter-wave terahertz spectrum measurement method of the Fabry-Perot interferometer can further optimize the spectral resolution and sensitivity of the system. Through multiple interference superpositions, the FP interferometer can effectively screen out narrowband spectra and enhance the strength and quality of the signal. This combination can significantly improve the detection performance of the terahertz system, especially in applications such as material analysis, environmental monitoring, and high-resolution imaging, providing higher accuracy and stability.

[0024] In the present invention, the resonance peak detection technology of the Fabry-Perot interferometer is used to accurately extract the resonance peak information of the terahertz wave using advanced signal processing technology, such as fast Fourier transform. Precise control of the scanning mechanism: The scanning mechanism can change the cavity length of the FP cavity with sub-wavelength accuracy, which is crucial for narrow linewidth measurement.

[0025] The main advantages and features are: high-precision measurement of narrow linewidth, signal enhancement through FP cavity interference, and accurate measurement of narrow linewidth radiation in the millimeter wave and terahertz frequency bands, which is especially suitable for low-power signal sources and improves measurement accuracy to hundreds of kHz.

[0026] Good adaptability to signals of different power levels: This test method is not strictly limited by signal power. It is suitable for strong signal scenarios and can maintain high measurement accuracy under weak signal conditions.

[0027] Strong environmental adaptability: Compared with traditional spectrum analysis methods, this method has low dependence on the experimental environment, greatly reducing the cost and difficulty of the experiment, making the implementation process easier. It includes precise scanning control, data acquisition and signal processing modules, which can realize the automation of spectrum measurement and support real-time adjustment and interaction.

[0028] Combine the following Figure 1 The invention discloses a narrow linewidth millimeter-wave terahertz spectrum measuring device based on a Fabry-Perot interferometer, comprising: Fabry-Perot interferometer, terahertz lens, power detection device 7 and line width analysis device 8; The radiation signal of the radiation source 1 to be measured generates a focusing signal 6 after passing through the terahertz lens and the Fabry-Perot interferometer; The focused signal 6 is input to the power detection device 7 to perform spectrum analysis of the radiation signal, and the focused signal 6 is input to the line width analysis device 8 to perform line width analysis of the radiation signal.

[0029] In the present invention, the terahertz lens comprises: a first terahertz lens 2 and a second terahertz lens 5; The Fabry-Perot interferometer is arranged between the first terahertz lens 2 and the second terahertz lens 5 .

[0030] The main object in the experiment or test, the radiation frequency band is millimeter wave terahertz, and the power range is wide.

[0031] The first terahertz lens 2 receives the radiation signal emitted by the radiation source 1 to be measured, and focuses the radiation signal into a parallel light beam through the first terahertz lens 2 to generate a collimated terahertz signal.

[0032] Specifically, the Fabry-Perot interferometer includes: a first reflector 3 and a second reflector 4; The first reflector 3 is parallel to the second reflector 4, and the distance between the first reflector 3 and the second reflector 4 is adjustable; An optical resonant cavity is formed based on the first reflecting mirror 3, the second reflecting mirror 4 and the gap therebetween.

[0033] The collimated terahertz signal enters the optical resonant cavity, is reflected and interfered multiple times between the first reflector 3 and the second reflector 4 to form a standing wave, and is emitted from the second reflector 4 to generate an interference signal.

[0034] In the present invention, the collimated radiation signal is vertically incident on the first reflector 3 of the FP interferometer. The incident wave is reflected multiple times in the interferometer to form an interference effect, and then emitted. When the collimated terahertz signal is incident on the first reflector 3 of the optical resonant cavity, part of the light beam is reflected, and part of the light beam passes through the first reflector 3 into the cavity. In the optical resonant cavity, the light beam will be reflected multiple times between two parallel reflectors. Each reflected light beam will interfere with other light beams in the cavity, and these interferences can be constructive interference or destructive interference, depending on the phase relationship of the light beams. By controlling the distance between the first reflector 3 and the second reflector 4, an interference signal is obtained, and the amplitude of the signal to be measured is enhanced.

[0035] The interference signal is focused by the second terahertz lens 5 to generate a focusing signal 6 .

[0036] The focused signal 6 enters the power detection device 7, and the signal strength is detected by the power detection device 7, and the spectrum information of the radiation signal is obtained after Fourier transformation. The focused signal 6 enters the line width analysis device 8 for denoising, filtering and frequency domain transformation, and completes the preprocessing, and the preprocessed focused signal 6 is subjected to line width analysis.

[0037] The present invention utilizes the multi-beam interference phenomenon of the FP interferometer to enhance the light intensity of a specific wavelength, so as to realize the precise measurement of narrow linewidth radiation; through the interference effect of the FP interferometer, the intensity and quality of the signal are enhanced, and the detection performance of the terahertz system is significantly improved; it can adapt to a wide power range from weak radiation to strong radiation sources, and is not strictly limited by the signal power; it can adapt to a wide power range from weak radiation to strong radiation sources, and is not strictly limited by the signal power; by precisely controlling the cavity length of the FP cavity, the narrow linewidth measurement is realized with sub-wavelength accuracy; through data acquisition and signal processing, including a signal preprocessing procedure of denoising, filtering and frequency domain transformation, and a resonance peak detection technology, the automation and real-time adjustment of the spectrum measurement are realized; it can realize a narrow linewidth measurement accuracy of up to the order of hundreds of kHz, and is particularly suitable for low-power small signal radiation sources.

[0038] refer to Figure 2 The present invention also discloses a method for measuring a narrow linewidth millimeter-wave terahertz spectrum based on a Fabry-Perot interferometer, comprising: Step 100, injecting a radiation signal emitted by a radiation source 1 to be measured into a first terahertz lens 2, and generating a collimated terahertz signal through the first terahertz lens 2; Step 200: The collimated terahertz signal is reflected and interfered multiple times in the optical resonant cavity to form a standing wave, which is emitted from the second reflector 4 to generate an interference signal; Step 300, the interference signal is focused by a second terahertz lens 5 to generate a focusing signal 6; Step 400 : Based on the focus signal 6 , spectrum analysis and line width analysis are performed by a power detection device 7 and a line width analysis device 8 .

[0039] Specifically, the frequency band of the signal source to be tested is millimeter wave terahertz. The FP cavity is an optical resonant cavity composed of two parallel mirrors, which can produce multi-beam interference phenomenon. Its working principle is based on the multiple reflections and interference of light waves between the two mirrors. When the light of meets the resonance condition, a standing wave will be formed in the cavity, thereby enhancing the light intensity of this wavelength, while the light of other wavelengths will be weakened due to interference destructive phase. L satisfy.

[0040] (1).

[0041] The radiation spectrum is tested using a scanning FP interferometer. The power detection device 7 uses a GC-1P model Golay detector produced by a certain company, which can detect a frequency range of 37.5GHz-20THz, and the minimum detectable power is less than 1nW, which meets the requirements. In addition, other types of terahertz power detectors such as thermal radiometers, terahertz antennas, monolithic microwave integrated circuits, photodetectors, etc. can also be used. The present invention does not impose special restrictions on the type of power detector. The reflectors at both ends of the FP interferometer should use materials that can simultaneously reflect and transmit terahertz waves, such as high-resistance silicon, 4-methylpentene (TPX), and quartz crystals.

[0042] The radiation signal collimated by the first terahertz lens 2 is vertically incident on the FP interferometer, reflected and interfered between the two mirrors for many times, and the interfered signal is focused by the terahertz lens and sent to the power detection device 7. When the radiation wavelength λ and the distance L between the mirrors satisfy equation (1), constructive interference occurs and the interference signal intensity is enhanced. Therefore, by scanning the distance L between the mirrors, recording the change in the intensity of the interference signal detected by the detector, and then obtaining the spectrum of the signal to be detected after Fourier transformation. In the process of line width analysis, a set of signal preprocessing procedures including denoising, filtering and frequency domain transformation is implemented, which can effectively extract useful information from the collected signal and suppress the interference of noise.

[0043] According to the basic principle of Fourier transform, the maximum cavity length of the FP interferometer determines the measurement accuracy of the signal line width. The larger the maximum cavity length, the higher the line width measurement accuracy. Since the maximum cavity length of the FP interferometer used in the present invention can be set arbitrarily, extremely high terahertz signal line width measurement accuracy can be achieved in theory. Under laboratory conditions, the maximum cavity length of the FP cavity can usually reach tens of centimeters or even meters, and the corresponding line width test accuracy can reach ~100 kHz. More importantly, it solves the problem of narrow line width measurement of low-power small signal radiation sources and reduces the power requirements of the radiation source for line width measurement.

[0044] The invention provides a method for measuring narrow-linewidth millimeter-wave terahertz spectrum based on a Fabry-Perot interferometer, which improves the measurement accuracy of narrow-linewidth radiation in the millimeter-wave and terahertz frequency bands through interference enhancement of the Fabry-Perot interferometer; can adapt to signals of different power levels, including low-power small signals, and expands the application scope of the measurement; reduces the dependence on the experimental environment, makes the measurement process simpler and reduces the cost; supports real-time adjustment and interaction through automated data acquisition and signal processing, and improves the flexibility and efficiency of the measurement; and provides an effective solution to the problems of low narrow-linewidth measurement accuracy and high requirements on radiation power and experimental environment in the prior art; improves the stability and reliability of the system through precise control and advanced signal processing technology.

[0045] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0046] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A narrow linewidth millimeter-wave terahertz spectrum measurement device based on Fabry-Perot interferometer, characterized in that: include: Fabry-Perot interferometer, terahertz lens, power detection device and linewidth analysis device; The radiation signal of the radiation source to be measured generates a focusing signal after passing through the terahertz lens and the Fabry-Perot interferometer; The focused signal is input into the power detection device to perform spectrum analysis of the radiation signal, and the focused signal is input into the line width analysis device to perform line width analysis of the radiation signal.

2. The narrow linewidth millimeter-wave terahertz spectrum measurement device based on Fabry-Perot interferometer according to claim 1, characterized in that: The terahertz lens comprises: a first terahertz lens and a second terahertz lens; The Fabry-Perot interferometer is arranged between the first terahertz lens and the second terahertz lens.

3. The narrow linewidth millimeter-wave terahertz spectrum measurement device based on Fabry-Perot interferometer according to claim 2, characterized in that: The first terahertz lens receives a radiation signal emitted by a radiation source to be measured, and focuses the radiation signal into a parallel light beam through the first terahertz lens to generate a collimated terahertz signal.

4. The narrow linewidth millimeter-wave terahertz spectrum measurement device based on Fabry-Perot interferometer according to claim 1, characterized in that: The Fabry-Perot interferometer comprises: a first reflecting mirror and a second reflecting mirror; The first reflector is parallel to the second reflector, and the distance between the first reflector and the second reflector is adjustable; An optical resonant cavity is formed based on the first reflecting mirror, the second reflecting mirror and the spacing gap therebetween.

5. The narrow linewidth millimeter-wave terahertz spectrum measurement device based on Fabry-Perot interferometer according to claim 3, characterized in that: The collimated terahertz signal enters the optical resonant cavity, is reflected and interfered multiple times between the first reflector and the second reflector to form a standing wave, and is emitted from the second reflector to generate an interference signal.

6. The narrow linewidth millimeter-wave terahertz spectrum measurement device based on Fabry-Perot interferometer according to claim 5, characterized in that: The interference signal is focused by a second terahertz lens to generate a focusing signal.

7. The narrow linewidth millimeter-wave terahertz spectrum measurement device based on Fabry-Perot interferometer according to claim 1, characterized in that: The focused signal enters a power detection device, through which signal strength detection is performed, and spectrum information of the radiation signal is obtained after Fourier transformation.

8. The narrow linewidth millimeter-wave terahertz spectrum measurement device based on Fabry-Perot interferometer according to claim 1, characterized in that: The focused signal enters the line width analysis device for denoising, filtering and frequency domain transformation to complete preprocessing, and line width analysis is performed on the preprocessed focused signal.

9. A method for measuring narrow linewidth millimeter-wave terahertz spectrum based on Fabry-Perot interferometer, characterized in that: include: The radiation signal emitted by the radiation source to be measured is injected into the first terahertz lens, and a collimated terahertz signal is generated through the first terahertz lens; The collimated terahertz signal is reflected and interfered multiple times in the optical resonant cavity to form a standing wave, which is emitted from the second reflector to generate an interference signal; The interference signal is focused by a second terahertz lens to generate a focusing signal; Based on the focused signal, spectrum analysis and linewidth analysis are performed through a power detection device and a linewidth analysis device.

10. The narrow linewidth millimeter-wave terahertz spectrum measurement method based on Fabry-Perot interferometer according to claim 9, characterized in that: The cavity length of the optical resonant cavity is adjusted by changing the spacing between the first reflector and the second reflector in the optical resonant cavity, and the amplitude of the incident collimated terahertz signal is enhanced to obtain an interference signal.

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