阅读说明：本技术 太赫兹多模连续波振幅光谱系统和太赫兹信号产生装置 (Terahertz multimode continuous wave amplitude spectrum system and terahertz signal generating device ) 是由 杨彬 张艳东 丁庆 于 2019-09-18 设计创作，主要内容包括：本申请适用于太赫兹成像技术领域,提供了太赫兹多模连续波振幅光谱系统和太赫兹信号产生装置,太赫兹信号产生装置包括至少四个激光信号产生模块和至少三个光混频模块,第一激光信号产生模块和第二激光信号产生模块输出的激光信号进行混频,第三激光信号产生模块和第四激光信号产生模块输出的激光信号进行混频,然后再将混频后的激光信号再进行混频,最后输出太赫兹信号。该太赫兹信号产生装置能够产生较宽频率范围的太赫兹信号。并且,通过两两混频最后再混频的方式能够在保证宽频的情况下最大限度降低激光信号产生模块的投入个数,降低了结构复杂度,在利用产生的太赫兹信号进行检测时检测速度也会变得很快,不需要借助于其他设备即可实现。(The terahertz signal generating device comprises at least four laser signal generating modules and at least three optical frequency mixing modules, laser signals output by the first laser signal generating module and the second laser signal generating module are subjected to frequency mixing, laser signals output by the third laser signal generating module and the fourth laser signal generating module are subjected to frequency mixing, then the laser signals after frequency mixing are subjected to frequency mixing, and finally the terahertz signals are output. The terahertz signal generating device can generate terahertz signals in a wider frequency range. In addition, the input number of the laser signal generation modules can be reduced to the maximum extent under the condition of ensuring the broadband through a mode of mixing two by two and finally mixing again, the structural complexity is reduced, the detection speed is also fast when the generated terahertz signals are used for detection, and the detection can be realized without other equipment.)

1. A terahertz signal generating apparatus, comprising:

at least four laser signal generating modules; and

at least three optical mixing modules;

the at least four laser signal generating modules comprise a first laser signal generating module, a second laser signal generating module, a third laser signal generating module and a fourth laser signal generating module, the at least three optical frequency mixing modules comprise a first optical frequency mixing module, a second optical frequency mixing module and a third optical frequency mixing module, a laser signal output end of the first laser signal generating module is connected with a first optical signal input end of the first optical frequency mixing module, a laser signal output end of the second laser signal generating module is connected with a second optical signal input end of the first optical frequency mixing module, a laser signal output end of the third laser signal generating module is connected with a first optical signal input end of the second optical frequency mixing module, and a laser signal output end of the fourth laser signal generating module is connected with a second optical signal input end of the second optical frequency mixing module, the optical signal output end of the first optical frequency mixing module is connected with the first optical signal input end of the third optical frequency mixing module, the optical signal output end of the second optical frequency mixing module is connected with the second optical signal input end of the third optical frequency mixing module, and the optical signal output end of the third optical frequency mixing module is used for outputting terahertz signals.

2. The terahertz signal generating apparatus of claim 1, wherein the first laser signal generating module and/or the second laser signal generating module comprises a laser and a modulator; the third laser signal generation module and/or the fourth laser signal generation module comprise a laser and a modulator.

3. The terahertz signal generating apparatus of claim 2, further comprising a laser frequency adjustment module, the laser frequency adjustment module being connected to the modulator.

4. A terahertz multimode continuous wave amplitude spectroscopy system, comprising:

a terahertz signal generating device; and

a detection device;

the terahertz signal generating device includes:

at least four laser signal generating modules; and

at least three optical mixing modules;

the at least four laser signal generating modules comprise a first laser signal generating module, a second laser signal generating module, a third laser signal generating module and a fourth laser signal generating module, the at least three optical frequency mixing modules comprise a first optical frequency mixing module, a second optical frequency mixing module and a third optical frequency mixing module, a laser signal output end of the first laser signal generating module is connected with a first optical signal input end of the first optical frequency mixing module, a laser signal output end of the second laser signal generating module is connected with a second optical signal input end of the first optical frequency mixing module, a laser signal output end of the third laser signal generating module is connected with a first optical signal input end of the second optical frequency mixing module, and a laser signal output end of the fourth laser signal generating module is connected with a second optical signal input end of the second optical frequency mixing module, an optical signal output end of the first optical frequency mixing module is connected with a first optical signal input end of the third optical frequency mixing module, an optical signal output end of the second optical frequency mixing module is connected with a second optical signal input end of the third optical frequency mixing module, and an optical signal output end of the third optical frequency mixing module is used for outputting terahertz signals;

and an object to be detected is placed between the optical signal output end of the third optical frequency mixing module and the detection device.

5. The terahertz multimode continuous wave amplitude spectroscopy system of claim 4, wherein the first and/or second laser signal generating module comprises a laser and a modulator; the third laser signal generation module and/or the fourth laser signal generation module comprise a laser and a modulator.

6. The terahertz multimode continuous wave amplitude spectroscopy system of claim 5, further comprising a laser frequency adjustment module coupled to the modulator.

7. The terahertz multimode continuous wave amplitude spectroscopy system of claim 4, 5 or 6, further comprising a transmitter, wherein the optical signal output of the third optical mixing module is connected to the optical signal input of the transmitter, and the optical signal output of the transmitter is configured to output the terahertz signal.

8. The terahertz multimode continuous wave amplitude spectroscopy system of claim 4, 5 or 6, further comprising a first lens module and a second lens module arranged between the optical signal output end of the third optical mixing module and the detection device, wherein the first lens module and the second lens module are arranged in sequence along the optical signal transmission direction, and the object to be measured is arranged between the first lens module and the second lens module.

9. The terahertz multimode continuous wave amplitude spectroscopy system as claimed in claim 4, 5 or 6, wherein the detection device comprises a detection module and an electrical spectrum analyzer, the detection module is used for detecting the terahertz signal after transmitting the object to be measured, and a signal output end of the detection module is connected with the electrical spectrum analyzer.

10. The terahertz multimode continuous wave amplitude spectroscopy system of claim 9, wherein the detection module is a schottky diode.

Technical Field

The application belongs to the technical field of terahertz imaging, and particularly relates to a terahertz multimode continuous wave amplitude spectrum system and a terahertz signal generating device.

Background

With the rapid development of the ultrafast laser technology and the further understanding of the action mechanism of terahertz radiation and substances by people, the terahertz radiation as a new and rapidly developed technology is widely concerned in many fields, and indicates a wide application prospect in many fields such as safety detection, medical diagnosis, wireless communication, pharmacy and the like. Terahertz spectrum provides a novel spectrum detection means, and the structure, the composition, the interaction and the like of a substance are researched by utilizing different characteristic absorption of the substance in a terahertz waveband. Compared with other technologies, the terahertz technology has the characteristics of high signal-to-noise ratio, wide dynamic range and the like, and can obtain time domain information, frequency domain information or intensity information of a sample in a terahertz waveband, so that important information such as a corresponding physical structure and chemical components of a substance is obtained.

The current terahertz spectrum is divided into pulse and continuous wave spectra due to the laser. The pulse terahertz spectrum can provide spectral information of an imaging object, even refractive index dispersion, and is high in resolution. The continuous wave terahertz spectrum has the characteristics of higher radiation power, simple system, low price, high imaging speed and convenience in use. The representative of the pulse spectroscopy system is a terahertz time-domain spectrometer. Continuous wave terahertz spectroscopy systems provide higher radiation intensity than pulsed spectroscopy systems, which is essentially an intensity (amplitude) imaging. A common continuous wave spectrum system is realized by continuous frequency tuning of a continuous wave laser, and information of a plurality of different frequencies needs to be acquired, but in order to acquire a terahertz signal in a wide frequency range, the conventional detection system has a very complex structure and relatively slow detection speed, and a subsequent selection process is also needed to realize the terahertz signal acquisition.

Disclosure of Invention

In view of this, the embodiments of the present application provide a terahertz multimode continuous wave amplitude spectroscopy system and a terahertz signal generating apparatus, so as to solve the problem that the structure of the existing detection system is very complex.

A first aspect of an embodiment of the present application provides a terahertz signal generating apparatus, including:

at least four laser signal generating modules; and

at least three optical mixing modules;

the at least four laser signal generating modules comprise a first laser signal generating module, a second laser signal generating module, a third laser signal generating module and a fourth laser signal generating module, the at least three optical frequency mixing modules comprise a first optical frequency mixing module, a second optical frequency mixing module and a third optical frequency mixing module, a laser signal output end of the first laser signal generating module is connected with a first optical signal input end of the first optical frequency mixing module, a laser signal output end of the second laser signal generating module is connected with a second optical signal input end of the first optical frequency mixing module, a laser signal output end of the third laser signal generating module is connected with a first optical signal input end of the second optical frequency mixing module, and a laser signal output end of the fourth laser signal generating module is connected with a second optical signal input end of the second optical frequency mixing module, the optical signal output end of the first optical frequency mixing module is connected with the first optical signal input end of the third optical frequency mixing module, the optical signal output end of the second optical frequency mixing module is connected with the second optical signal input end of the third optical frequency mixing module, and the optical signal output end of the third optical frequency mixing module is used for outputting terahertz signals.

Optionally, the first laser signal generation module and/or the second laser signal generation module comprises a laser and a modulator; the third laser signal generation module and/or the fourth laser signal generation module comprise a laser and a modulator.

Optionally, the terahertz signal generating device further comprises a laser frequency adjusting module, and the laser frequency adjusting module is connected to the modulator.

A second aspect of an embodiment of the present application provides a terahertz multimode continuous wave amplitude spectroscopy system, including:

a terahertz signal generating device; and

a detection device;

the terahertz signal generating device includes:

at least four laser signal generating modules; and

at least three optical mixing modules;

the at least four laser signal generating modules comprise a first laser signal generating module, a second laser signal generating module, a third laser signal generating module and a fourth laser signal generating module, the at least three optical frequency mixing modules comprise a first optical frequency mixing module, a second optical frequency mixing module and a third optical frequency mixing module, a laser signal output end of the first laser signal generating module is connected with a first optical signal input end of the first optical frequency mixing module, a laser signal output end of the second laser signal generating module is connected with a second optical signal input end of the first optical frequency mixing module, a laser signal output end of the third laser signal generating module is connected with a first optical signal input end of the second optical frequency mixing module, and a laser signal output end of the fourth laser signal generating module is connected with a second optical signal input end of the second optical frequency mixing module, an optical signal output end of the first optical frequency mixing module is connected with a first optical signal input end of the third optical frequency mixing module, an optical signal output end of the second optical frequency mixing module is connected with a second optical signal input end of the third optical frequency mixing module, and an optical signal output end of the third optical frequency mixing module is used for outputting terahertz signals;

and an object to be detected is placed between the optical signal output end of the third optical frequency mixing module and the detection device.

Optionally, the first laser signal generation module and/or the second laser signal generation module comprises a laser and a modulator; the third laser signal generation module and/or the fourth laser signal generation module comprise a laser and a modulator.

Optionally, the terahertz multimode continuous wave amplitude spectroscopy system further includes a laser frequency adjusting module, and the laser frequency adjusting module is connected to the modulator.

Optionally, the terahertz multimode continuous wave amplitude spectroscopy system further includes a transmitter, an optical signal output end of the third optical mixing module is connected to an optical signal input end of the transmitter, and an optical signal output end of the transmitter is configured to output a terahertz signal.

Optionally, the terahertz multimode continuous wave amplitude spectroscopy system further includes a first lens module and a second lens module, which are disposed between the optical signal output end of the third optical mixing module and the detection device, the first lens module and the second lens module are sequentially disposed along the optical signal transmission direction, and the object to be detected is disposed between the first lens module and the second lens module.

Optionally, the detection device includes a detection module and an electrical spectrum analyzer, the detection module is configured to detect the terahertz signal after transmitting the object to be detected, and a signal output end of the detection module is connected to the electrical spectrum analyzer.

Optionally, the detection module is a schottky diode.

Compared with the prior art, the embodiment of the application has the advantages that: the laser signals of every two laser signal generation modules are firstly mixed, then the mixed laser signals are mixed, and finally terahertz signals are output, and the terahertz signals are generated through a difference frequency principle. The frequency of the laser signal output by each laser signal generation module can be set to ensure that the width of the frequency of the generated terahertz signal is large, namely the terahertz signal with a wide frequency range can be generated. And the mode of mixing two by two and finally mixing frequency again can reduce the input number of the laser signal generating modules to the maximum extent under the condition of ensuring the broadband, not only reduces the structural complexity and ensures that the structure is simpler, correspondingly, the detection speed is also fast when the generated terahertz signal is used for detection, and the method can be realized without other equipment.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor.

Fig. 1 is a schematic view of a first structure of a terahertz signal generating apparatus according to an embodiment of the present application;

fig. 2 is a schematic diagram of a second structure of a terahertz signal generating apparatus according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a first structure of a terahertz multimode continuous wave amplitude spectroscopy system according to a second embodiment of the present application;

fig. 4 is a schematic diagram of a second structure of the terahertz multimode continuous wave amplitude spectroscopy system according to the second embodiment of the present application.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is also to be understood that the terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the specification of the present application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

In order to explain the technical means described in the present application, the following description will be given by way of specific embodiments.

Fig. 1 is a schematic diagram of a first circuit structure of a terahertz signal generating apparatus according to an embodiment of the present application. For convenience of explanation, only portions related to the embodiments of the present application are shown.

As shown in fig. 1, the terahertz signal generating apparatus includes a laser signal generating module and an optical mixing module. The number of the laser signal generating modules is at least four, and the laser signal generating modules are set according to actual needs, and the embodiment takes 4 as an example for explanation, which are the first laser signal generating module 101, the second laser signal generating module 102, the third laser signal generating module 103, and the fourth laser signal generating module 104, respectively. The number of the optical frequency mixing modules is adapted to the number of the laser signal generating modules, so that the number of the optical frequency mixing modules is at least three, and the optical frequency mixing modules are arranged according to actual needs, in this embodiment, 3 optical frequency mixing modules are taken as an example and are respectively the first optical frequency mixing module 105, the second optical frequency mixing module 106 and the third optical frequency mixing module 107, and each optical frequency mixing module may be a conventional optical frequency mixer.

The laser signal output end of the first laser signal generating module 101 is connected to the first optical signal input end of the first optical frequency mixing module 105 (connected via an optical fiber, the same applies hereinafter), the laser signal output end of the second laser signal generating module 102 is connected to the second optical signal input end of the first optical frequency mixing module 105, the laser signal output end of the third laser signal generating module 103 is connected to the first optical signal input end of the second optical frequency mixing module 106, and the laser signal output end of the fourth laser signal generating module 104 is connected to the second optical signal input end of the second optical frequency mixing module 106. An optical signal output end of the first optical frequency mixing module 105 is connected to a first optical signal input end of the third optical frequency mixing module 107, an optical signal output end of the second optical frequency mixing module 106 is connected to a second optical signal input end of the third optical frequency mixing module 107, and an optical signal output end of the third optical frequency mixing module 107 is a terahertz signal output end of the terahertz signal generating device and is used for outputting a terahertz signal.

The frequencies of the laser signals output by the first laser signal generating module 101, the second laser signal generating module 102, the third laser signal generating module 103, and the fourth laser signal generating module 104 are all set according to actual needs, and certainly, the four laser signal generating modules cannot all generate laser signals with the same frequency, so that a part of the four laser signal generating modules may generate laser signals with the same frequency, and of course, the four laser signal generating modules may also generate laser signals with different frequencies, that is, the first laser signal generating module 101, the second laser signal generating module 102, the third laser signal generating module 103, and the fourth laser signal generating module 104 output laser signals with different frequencies. Moreover, the functions of the four laser signal generating modules are used for outputting laser signals, and the specific structure of the modules is not limited, for example, the following two implementation modes are provided: 1. the laser signal generation module can be a laser source such as a laser diode or the like, or a simple structure such as a laser diode and a modulator; 2. the laser signal output by each laser signal generating module may be a laser signal output by mixing at least two laser signals, in which case, the structure of the laser signal generating module is relatively complex, and is not just a laser diode and a modulator, but is formed by combining related structures, for example, the laser signal generating module includes at least two lasers (the at least two lasers are emitted by a laser source or are generated by mixing other groups of lasers) and at least one mixer, and the laser signal is output by laser mixing. Therefore, the structure of the laser signal generating module is not exclusive, and may be a laser source (such as a laser diode) for outputting an original laser signal, or a structure composed of a plurality of laser sources and a mixer, and outputs a laser signal after mixing or other related processing. In short, any structure of the laser signal generating module is within the protection range as long as the laser signal can be output.

In addition, the terahertz signal generating device may include other laser signal generating modules besides the first laser signal generating module 101, the second laser signal generating module 102, the third laser signal generating module 103 and the fourth laser signal generating module 104, and these other laser signal generating modules may be arranged on corresponding optical paths in the terahertz signal generating device according to actual needs, and perform frequency mixing with the relevant optical paths of the first laser signal generating module 101, the second laser signal generating module 102, the third laser signal generating module 103 and the fourth laser signal generating module 104.

The laser signals generated by the first laser signal generating module 101 and the second laser signal generating module 102 are mixed by the first optical mixing module 105, and are output by the first optical mixing module 105; the laser signals generated by the third laser signal generation module 103 and the fourth laser signal generation module 104 are mixed by the second optical mixing module 106, and are output by the second optical mixing module 106; the laser signal output by the first optical mixing module 105 and the laser signal output by the second optical mixing module 106 are mixed by the third optical mixing module 107 to output a terahertz signal, and the terahertz signal is generated by the difference frequency principle. Therefore, the terahertz signal generating device can generate a terahertz signal in a wide frequency range. And the mode of mixing two by two and finally mixing frequency again can reduce the input number of the laser signal generating modules to the maximum extent under the condition of ensuring the broadband, not only reduces the structural complexity and ensures that the structure is simpler, correspondingly, the detection speed is also fast when the generated terahertz signal is used for detection, and the method can be realized without other equipment.

Fig. 2 is a schematic diagram of a second circuit structure of the terahertz signal generating apparatus according to the first embodiment of the present application. For convenience of explanation, only portions related to the embodiments of the present application are shown.

As shown in fig. 2, the terahertz signal generating apparatus includes a laser signal generating module and an optical mixing module. The laser signal generating module is a first laser signal generating module, a second laser signal generating module, a third laser signal generating module and a fourth laser signal generating module. The optical mixing modules are a first optical mixing module 208, a second optical mixing module 209 and a third optical mixing module 210, respectively, and each optical mixing module may be a conventional optical mixer.

The first laser signal generation module and/or the second laser signal generation module comprise a laser and a modulator; the third laser signal generation module and/or the fourth laser signal generation module comprises a laser and a modulator. Namely: at least one of the first laser signal generation module and the second laser signal generation module comprises a laser and a modulator, and at least one of the third laser signal generation module and the fourth laser signal generation module comprises a laser and a modulator. In this embodiment, the first laser signal generating module is a laser diode 201, and a laser signal output end of the laser diode 201 is connected to a first optical signal input end of the first optical mixing module 208 (connected by an optical fiber, the same applies below); the second laser signal generating module comprises a laser diode 202 and a modulator 205, a laser signal output end of the laser diode 202 is connected with a laser signal input end of the modulator 205, and a laser signal output end of the modulator 205 is connected with a second optical signal input end of the first optical mixing module 208; the third laser signal generating module comprises a laser diode 203 and a modulator 206, a laser signal output end of the laser diode 203 is connected with a laser signal input end of the modulator 206, a laser signal output end of the modulator 206 is connected with a first optical signal input end of the second optical mixing module 209, the fourth laser signal generating module comprises a laser diode 204 and a modulator 207, a laser signal output end of the laser diode 204 is connected with a laser signal input end of the modulator 207, and a laser signal output end of the modulator 207 is connected with a second optical signal input end of the second optical mixing module 209; an optical signal output end of the first optical frequency mixing module 208 is connected to a first optical signal input end of the third optical frequency mixing module 210, an optical signal output end of the second optical frequency mixing module 209 is connected to a second optical signal input end of the third optical frequency mixing module 210, and an optical signal output end of the third optical frequency mixing module 210 is a terahertz signal output end of the terahertz signal generating device and is used for outputting a terahertz signal.

Since the first laser signal generation module only has the laser diode 201, the output laser signal is the originally generated laser signal, and the frequency of the originally generated laser signal is the original frequency of the laser light and serves as the reference frequency. The second laser signal generation module, the third laser signal generation module and the fourth laser signal generation module are all provided with laser diodes and modulators, and the modulators can perform frequency modulation on laser signals generated by the laser diodes so as to change the frequency. In order to adjust the laser frequency conveniently, the terahertz signal generating device further comprises a laser frequency adjusting module 211, wherein the laser frequency adjusting module 211 is connected with the modulator 205, the modulator 206 and the modulator 207 and is used for adjusting parameters of the three modulators so as to adjust the laser frequency, and specific laser frequency values of the three modulators are set according to actual needs. The laser frequency adjusting module 211 is a conventional frequency generator, and is not described in detail.

Therefore, the first laser signal generation module and the second, third and fourth laser signal generation modules output laser with different frequencies. The laser output by the first laser signal generation module and the laser output by the second laser signal generation module are mixed by the first optical mixing module 208, the laser output by the third laser signal generation module and the laser output by the fourth laser signal generation module are mixed by the second optical mixing module 209, the optical signal mixed by the first optical mixing module 208 and the optical signal mixed by the second optical mixing module 209 are mixed by the third optical mixing module 210, the generation of terahertz signals is realized by using the difference frequency principle, and the generated terahertz frequency is modulated by the corresponding frequency of the original laser source, so that the multimode continuous system is realized.

In addition, the terahertz signal generating device can include other laser signal generating modules besides the first laser signal generating module, the second laser signal generating module, the third laser signal generating module and the fourth laser signal generating module, and the other laser signal generating modules can be arranged on corresponding optical paths in the terahertz signal generating device according to actual needs and perform frequency mixing with related optical paths of the first laser signal generating module, the second laser signal generating module, the third laser signal generating module and the fourth laser signal generating module.

Therefore, the terahertz signal generating device can generate a terahertz signal in a wide frequency range. And the mode of mixing two by two and finally mixing frequency again can reduce the input number of the laser signal generating modules to the maximum extent under the condition of ensuring the broadband, not only reduces the structural complexity and ensures that the structure is simpler, correspondingly, the detection speed is also fast when the generated terahertz signal is used for detection, and the method can be realized without other equipment.

The second embodiment of the present application provides a terahertz multimode continuous wave amplitude spectroscopy system, which includes two major parts, one part is a terahertz signal generating device, and the other part is a detecting device 308. As shown in fig. 3, the terahertz signal generating apparatus includes a laser signal generating module and an optical mixing module. The number of the laser signal generating modules is at least four, and the laser signal generating modules are set according to actual needs, and the embodiment takes 4 as an example for description, and the number of the laser signal generating modules is the first laser signal generating module 301, the second laser signal generating module 302, the third laser signal generating module 303, and the fourth laser signal generating module 304. The number of the optical frequency mixing modules is adapted to the number of the laser signal generating modules, so the number of the optical frequency mixing modules is at least three, and the number is set according to actual needs, in this embodiment, 3 optical frequency mixing modules are taken as an example and are respectively the first optical frequency mixing module 305, the second optical frequency mixing module 306 and the third optical frequency mixing module 307, and each optical frequency mixing module may be a conventional optical frequency mixer.

The laser signal output end of the first laser signal generating module 301 is connected to the first optical signal input end of the first optical frequency mixing module 305 (connected via an optical fiber, the same applies hereinafter), the laser signal output end of the second laser signal generating module 302 is connected to the second optical signal input end of the first optical frequency mixing module 305, the laser signal output end of the third laser signal generating module 303 is connected to the first optical signal input end of the second optical frequency mixing module 306, and the laser signal output end of the fourth laser signal generating module 304 is connected to the second optical signal input end of the second optical frequency mixing module 306. An optical signal output end of the first optical frequency mixing module 305 is connected to a first optical signal input end of the third optical frequency mixing module 307, an optical signal output end of the second optical frequency mixing module 306 is connected to a second optical signal input end of the third optical frequency mixing module 307, and an optical signal output end of the third optical frequency mixing module 307 is a terahertz signal output end of the terahertz signal generating device and is used for outputting a terahertz signal.

The frequencies of the laser signals output by the first laser signal generating module 301, the second laser signal generating module 302, the third laser signal generating module 303 and the fourth laser signal generating module 304 are all set according to actual needs, and certainly, the four laser signal generating modules cannot all generate laser signals with the same frequency, so that a part of the four laser signal generating modules may generate laser signals with the same frequency, and of course, the four laser signal generating modules may also generate laser signals with different frequencies, that is, the first laser signal generating module 301, the second laser signal generating module 302, the third laser signal generating module 303 and the fourth laser signal generating module 304 output laser signals with different frequencies. Moreover, the functions of the four laser signal generating modules are used for outputting laser signals, and the specific structure of the modules is not limited, for example, the following two implementation modes are provided: 1. the laser signal generation module can be a laser source such as a laser diode or the like, or a simple structure such as a laser diode and a modulator; 2. the laser signal output by each laser signal generation module may be a laser signal output by mixing at least two laser signals (the at least two laser signals are emitted by a laser source or generated by mixing other groups of laser light), and in this case, the structure of the laser signal generation module is relatively complex, and the laser signal generation module includes at least two laser beams and at least one mixer instead of a laser diode and a modulator, and outputs the laser signal by laser mixing. Therefore, the structure of the laser signal generating module is not exclusive, and may be a laser source (such as a laser diode) for outputting an original laser signal, or a structure composed of a plurality of laser sources and a mixer, and outputs a laser signal after mixing or other related processing. In short, any structure of the laser signal generating module is within the protection range as long as the laser signal can be output.

In addition, the terahertz signal generating device may include other laser signal generating modules besides the first laser signal generating module 301, the second laser signal generating module 302, the third laser signal generating module 303 and the fourth laser signal generating module 304, and these other laser signal generating modules may be arranged on corresponding optical paths in the terahertz signal generating device according to actual needs, and perform frequency mixing with the relevant optical paths of the first laser signal generating module 301, the second laser signal generating module 302, the third laser signal generating module 303 and the fourth laser signal generating module 304.

The laser signals generated by the first laser signal generation module 301 and the second laser signal generation module 302 are mixed by the first optical mixing module 305, and are output by the first optical mixing module 305; the laser signals generated by the third laser signal generating module 303 and the fourth laser signal generating module 304 are mixed by the second optical mixing module 306, and are output by the second optical mixing module 306; the laser signal output by the first optical mixing module 305 and the laser signal output by the second optical mixing module 306 are mixed by the third optical mixing module 307, and a terahertz signal is output, and the generation of the terahertz signal is realized by the difference frequency principle. Therefore, the terahertz signal generating device can generate a terahertz signal in a wide frequency range. And the mode of mixing two by two and finally mixing frequency again can reduce the input number of the laser signal generating modules to the maximum extent under the condition of ensuring the broadband, not only reduces the structural complexity and ensures that the structure is simpler, correspondingly, the detection speed is also fast when the generated terahertz signal is used for detection, and the method can be realized without other equipment.

The object to be measured 309 is disposed on the optical path between the optical signal output end of the third optical mixing module 307 and the detection device 308, that is, in the detection region formed between the optical signal output end of the third optical mixing module 307 and the detection device 308. The terahertz signal output by the optical signal output end of the third optical mixing module 307 irradiates the object to be detected 309, the detecting device 308 receives the terahertz signal transmitted by the object to be detected 309 and performs corresponding analysis, and the analysis principle and process of the detecting device 308 belong to the prior art and are not described again.

The second terahertz multimode continuous wave amplitude spectroscopy system provided by the embodiment of the application comprises two parts, wherein one part is a terahertz signal generating device, and the other part is a detecting device.

As shown in fig. 4, the terahertz signal generating apparatus includes a laser signal generating module and an optical mixing module. The laser signal generating module is a first laser signal generating module, a second laser signal generating module, a third laser signal generating module and a fourth laser signal generating module. The optical mixing modules are a first optical mixing module 408, a second optical mixing module 409 and a third optical mixing module 410, respectively, each of which may be a conventional optical mixer.

The first laser signal generation module and/or the second laser signal generation module comprise a laser and a modulator; the third laser signal generation module and/or the fourth laser signal generation module comprises a laser and a modulator. Namely: at least one of the first laser signal generation module and the second laser signal generation module comprises a laser and a modulator, and at least one of the third laser signal generation module and the fourth laser signal generation module comprises a laser and a modulator. In this embodiment, the first laser signal generating module is a laser diode 401, and a laser signal output end of the laser diode 401 is connected to a first optical signal input end of the first optical mixing module 408 (connected by an optical fiber, the same applies below); the second laser signal generating module comprises a laser diode 402 and a modulator 405, a laser signal output end of the laser diode 402 is connected with a laser signal input end of the modulator 405, and a laser signal output end of the modulator 405 is connected with a second optical signal input end of the first optical mixing module 408; the third laser signal generating module comprises a laser diode 403 and a modulator 406, a laser signal output end of the laser diode 403 is connected with a laser signal input end of the modulator 406, a laser signal output end of the modulator 406 is connected with a first optical signal input end of the second optical mixing module 409, the fourth laser signal generating module comprises a laser diode 404 and a modulator 407, a laser signal output end of the laser diode 404 is connected with a laser signal input end of the modulator 407, and a laser signal output end of the modulator 407 is connected with a second optical signal input end of the second optical mixing module 409; an optical signal output end of the first optical frequency mixing module 408 is connected to a first optical signal input end of the third optical frequency mixing module 410, an optical signal output end of the second optical frequency mixing module 409 is connected to a second optical signal input end of the third optical frequency mixing module 410, and an optical signal output end of the third optical frequency mixing module 410 is a terahertz signal output end of the terahertz signal generating device and is used for outputting a terahertz signal.

Since the first laser signal generation module only has the laser diode 401, the output laser signal is the originally generated laser signal, and the frequency of the originally generated laser signal is the original frequency of the laser light and serves as the reference frequency. The second laser signal generation module, the third laser signal generation module and the fourth laser signal generation module are all provided with laser diodes and modulators, and the modulators can perform frequency modulation on laser signals generated by the laser diodes so as to change the frequency. In order to adjust the laser frequency conveniently, the terahertz signal generating device further comprises a laser frequency adjusting module 411, wherein the laser frequency adjusting module 411 is connected with the modulator 405, the modulator 406 and the modulator 407, and is used for adjusting parameters of the three modulators to adjust the laser frequency, and setting specific laser frequency values of the three modulators according to actual needs. The laser frequency adjusting module 411 is a conventional frequency generator, and is not described in detail.

Therefore, the first laser signal generation module and the second, third and fourth laser signal generation modules output laser with different frequencies. The laser output by the first laser signal generation module and the laser output by the second laser signal generation module are mixed by the first optical mixing module 408, the laser output by the third laser signal generation module and the laser output by the fourth laser signal generation module are mixed by the second optical mixing module 409, the optical signal mixed by the first optical mixing module 408 and the optical signal mixed by the second optical mixing module 409 are mixed by the third optical mixing module 410, the generation of terahertz signals is realized by using the difference frequency principle, and the generated terahertz frequency is modulated by the corresponding frequency of the original laser source, so that the multimode continuous system is realized.

In addition, the terahertz signal generating device may further include other laser signal generating modules besides the first laser signal generating module, the second laser signal generating module, the third laser signal generating module and the fourth laser signal generating module, and these other laser signal generating modules may be arranged on corresponding optical paths in the terahertz signal generating device according to actual needs, and perform frequency mixing with related optical paths of the first laser signal generating module, the second laser signal generating module, the third laser signal generating module and the fourth laser signal generating module.

In this embodiment, the terahertz multimode continuous wave amplitude spectroscopy system further includes a transmitter 412, an optical signal output end of the third optical mixing module 410 is connected to an optical signal input end of the transmitter 412, an optical signal output end of the transmitter 412 is used for outputting a terahertz signal, and the transmitter 412 is used for transmitting the terahertz signal generated by the terahertz signal generating device, and may be a conventional transmitter. Moreover, the terahertz multimode continuous wave amplitude spectroscopy system further comprises a first lens module 413 and a second lens module 415, the first lens module 413 and the second lens module 415 are arranged between the third optical mixing module 410 and the detection device, namely between the emitter 412 and the detection device, and are sequentially arranged along the optical signal transmission direction, and the object 414 to be detected is arranged between the first lens module 413 and the second lens module 415, namely a detection area is formed between the first lens module 413 and the second lens module 415. The first lens module 413 and the second lens module 415 can process the terahertz signal, for example, collimate the terahertz signal to reduce divergence of the terahertz signal, and in addition, the first lens module 413 and the second lens module 415 may be a single lens or may be formed by combining a plurality of lenses, and the specific number of lenses and the type of lenses are determined by actual conditions.

In the present embodiment, the detection apparatus includes a detection module 416 and an electrical spectrum analyzer 417 (the electrical spectrum analyzer 417 may be a conventional spectrum analyzer), and the detection module 416 is exemplified by a schottky diode, but may also be other detection devices. The schottky diode is used for detecting the terahertz signal after transmitting the object to be detected 414, and a signal output end of the schottky diode is connected with the electrical spectrum analyzer 417.

The terahertz signal output by the third optical mixing module 410 is sequentially irradiated onto the object 414 to be measured via the emitter 412 and the first lens module 413, the terahertz signal transmitted by the object 414 to be measured is detected by the schottky diode through the second lens module 415, the signal output by the detection is analyzed by the electrical spectrum analyzer 417, and all the difference sum and frequency are displayed on the spectrum image displayed by the electrical spectrum analyzer 417. Thus, the amplitude of each terahertz can be directly identified at the corresponding position of the spectrum image displayed by the electrical spectrum analyzer 417 by the terahertz multimode continuous wave amplitude spectroscopy system.

The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may be modified or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.