CN108683059A - The system and method for generating high-intensity broadband THz wave using liquid column - Google Patents

Abstract

The invention discloses a kind of system and method generating high-intensity broadband THz wave using liquid column, which includes the laser being successively set in light path, spectroscope, chopper, the first off-axis parabolic mirror and liquid column, wherein：The focal length of first off-axis parabolic mirror is 1 inch, the direction of liquid column is straight down, laser is for emitting a horizontal polarization laser beam, horizontal polarization laser beam is by being divided into a branch of pump light and a branch of detection light after spectroscope, pump light passes through after being modulated by chopper focuses on liquid column by the first off-axis parabolic mirror, is to form one to give off the terahertz radiation source of high-intensity broadband THz wave at liquid column.Present invention application liquid column generates THz wave and generation efficiency is high, system composition is simple, it is at low cost to build, is easy maintenance, stability height, the blank in current high-intensity broadband THz wave generation technology field is compensated for, there is stronger scientific research and actual application value.

Description

Systems and methods for generating high-intensity broadband terahertz waves using a liquid column

technical field

The invention relates to the technical field of terahertz waves, in particular to a system and method for generating high-intensity broadband terahertz waves by using a liquid column.

Background technique

In recent years, with the research on terahertz radiation sources, a large number of research results have proved that solid crystals, metal materials, gases or plasmas are all good terahertz radiation sources. However, there are very few research results on the use of liquids, especially liquid water or its plasma, to generate terahertz waves. In fact, liquid water has been studied for more than 10 years as a source of various electromagnetic waves. For example: High harmonics and white light are generated by the non-linear process of focusing ultrashort-pulse laser light onto water contained in cells, jets or droplets. Furthermore, the dynamics of liquid water irradiated by laser pulses has been studied for more than two decades. The reason why liquid water is hindered as a source of THz radiation may be because liquid water has very strong absorption properties in the THz frequency range. The power absorption coefficient of liquid water at 1 terahertz is about 220cm ^-1 , which means that when 3.6×10 ⁹ terahertz photons enter a 1mm thick water film, only one photon will be radiated. It can be seen that the loss of photons is very large and Terahertz generation is very inefficient.

Contents of the invention

The present invention provides a system and method for generating high-intensity broadband terahertz waves by using a liquid column to generate high-intensity broadband terahertz waves.

In order to achieve the above object, the present invention provides a system for generating high-intensity broadband terahertz waves using a liquid column, which includes a laser, a beam splitter, a chopper, a first off-axis parabolic reflector, and a liquid that are sequentially arranged on the optical path column, where:

The focal length of the first off-axis parabolic reflector is 1 inch,

The direction of the liquid column is vertically downward,

The laser is used to emit a horizontally polarized laser beam, and the horizontally polarized laser beam is divided into a beam of pump light and a beam of probe light after passing through the beam splitter, and the pump light is modulated by the chopper and passed through the first The off-axis parabolic reflector focuses on the liquid column, and a terahertz wave radiation source capable of radiating high-intensity broadband terahertz waves is formed at the liquid column.

In an embodiment of the present invention, the laser is a femtosecond laser, and the chopping frequency of the chopper is 100-300 Hz.

In an embodiment of the present invention, the liquid in the liquid column is water, an inorganic solution or an organic solution.

In one embodiment of the present invention, the liquid in the liquid column is calcium chloride solution or carbon tetrachloride solution.

In an embodiment of the present invention, the diameter of the liquid column is 0.2um.

In an embodiment of the present invention, the liquid column is generated by a liquid column generating device, and the liquid column generating device includes a liquid pool, a water pump, a spray head, a first connecting pipe and a second connecting pipe, and the first connecting pipe The pipe is connected between the liquid pool and the water pump, the second connecting pipe is connected between the water pump and the spray head, and the water pump is used to draw the liquid in the liquid pool and increase it. pressure, and the liquid column is ejected from the nozzle, and the liquid in the liquid column flows back to the liquid pool.

In one embodiment of the present invention, the water pump is a variable frequency scroll self-priming electric pump with a rated power of 750w, the first connecting pipe is a latex hose, and the second connecting pipe is a metal connecting pipe and latex A combination of hoses, wherein the latex hose has an aperture of 3-10 mm, the metal connecting pipe has an aperture of 5-15 mm, and the nozzle is an aluminum alloy nozzle with an aperture of 0.1-1 mm.

In an embodiment of the present invention, the system for generating high-intensity broadband terahertz waves using a liquid column further includes a terahertz wave detection system, which includes a second off-axis parabolic mirror, a silicon wafer, and a third off-axis parabolic mirror , ZnTe crystal, first convex lens, terahertz wave detector and second convex lens, wherein:

The focal lengths of the second off-axis parabolic reflector and the third off-axis parabolic reflector are both 4 inches,

The second off-axis parabolic reflector converges the terahertz wave into a parallel beam, which is filtered by the silicon chip and projected to the third off-axis parabolic reflector to focus and form a focused beam. The focused beam The detection beam focused by the second convex lens is jointly focused on the ZnTe crystal and then passes through the first convex lens, and then the intensity is detected by the terahertz wave detector.

In an embodiment of the present invention, the terahertz wave detector is a self-balancing photodetector.

In an embodiment of the present invention, the terahertz wave radiation source radiates terahertz waves with different intensities at different angles in space, and the intensity of the terahertz waves is the largest in the direction where the radiation angle θ is 65°, and the radiation angle θ is defined as follows:

Define the direction of the laser projected from the first off-axis paraboloid to the liquid column as A, and the direction from the liquid column to the device for receiving terahertz waves as B, then the angle between A and B is the radiation angle θ, Define -180°<θ≤180°, define that the radiation angle θ is 0° when A and B are in the same direction, and 180° when A and B are in the opposite direction, and define that the radiation angle θ is 0° and rotates clockwise to The radiation angle θ is positive when the radiation angle θ is 180° between directions, otherwise it is negative.

The present invention also provides a method for generating a high-intensity broadband terahertz wave using a liquid column applied in the above system, which includes the following steps:

S1: the laser emits a horizontally polarized laser beam;

S2: the horizontally polarized laser beam is divided into a beam of pump light and a beam of probe light after passing through the beam splitter;

S3: the pump light is modulated by the chopper and focused on the liquid column through the first off-axis parabolic reflector;

S4: A terahertz wave radiation source is formed at the liquid column and radiates high-intensity broadband terahertz waves.

The system and method for generating high-intensity broadband terahertz waves provided by the present invention innovatively apply liquid columns to generate terahertz waves and have high generation efficiency. The system is simple in structure, low in construction cost, easy to maintain, and high in stability, making up for At present, there is a blank in the field of high-intensity broadband terahertz wave generation technology, which has strong scientific research and practical application value.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic composition diagram (top view) of a system for generating high-intensity broadband terahertz waves using a liquid column provided by the present invention;

Fig. 2 is the composition schematic diagram (side view) of the liquid column generating device among the present invention;

Fig. 3 is the time-domain waveform of the terahertz wave that the present invention produces;

Fig. 4 is the spectrogram of the terahertz wave that the present invention produces;

Fig. 5 is a numerical distribution diagram of the radiation angle θ viewed from a plan view.

Description of reference signs: 1-laser; 2-beam splitter; 3-chopper; 4-first off-axis parabolic reflector; 5-liquid column; 51-liquid pool; 52-water pump; 55-second connecting pipe; 6-terahertz wave detection system; 61-second off-axis parabolic reflector; 62-silicon wafer; 63-third off-axis parabolic reflector; 64-ZnTe crystal; 65-the first convex lens; 66-terahertz wave detector; 67-the second convex lens.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Fig. 1 is a schematic composition diagram (top view) of a system for producing a high-intensity broadband terahertz wave using a liquid column provided by the present invention, and Fig. 2 is a schematic composition diagram (side view) of a liquid column generation device in the present invention, as shown in Fig. 1 and Fig. As shown in 2, the system for generating high-intensity broadband terahertz waves by using a liquid column provided by the present invention includes a laser 1, a beam splitter 2, a chopper 3, a first off-axis parabolic reflector 4, and a liquid column sequentially arranged on the optical path 5, of which:

The focal length of the first off-axis parabolic mirror 4 is 1 inch,

The direction of the liquid column 5 is vertically downward, and it should be a continuous, stable liquid column with a fixed flow rate and no change in shape.

The laser 1 is used to emit a horizontally polarized laser beam. The horizontally polarized laser beam is divided into a beam of pump light and a beam of probe light after passing through the beam splitter 2. The pump light is modulated by the chopper 3 and reflected by the first off-axis paraboloid 4 The mirror focuses on the liquid column 5, and the liquid column 5 forms a terahertz wave radiation source capable of radiating high-intensity broadband terahertz waves.

The laser 1 in the present invention may be, for example, a femtosecond laser, and the chopping frequency of the chopper 3 may be, for example, 100-300 Hz.

In the present invention, the liquid in the liquid column 5 can be water, an inorganic solution (such as calcium chloride solution) or an organic solution (such as carbon tetrachloride solution).

In an embodiment of the present invention, the diameter of the liquid column 5 may be, for example, 0.2um, but the present invention is not limited thereto, and the diameter of the liquid column may be adjusted according to actual needs.

As shown in Figure 2, in the present embodiment, the liquid column 5 is produced by a liquid column generating device, and the liquid column generating device includes a liquid pool 51, a water pump 52, a spray nozzle 53, a first connecting pipe 54 and a second connecting pipe 55, the first connecting pipe 54 and the second connecting pipe 55. A connecting pipe 54 is connected between the liquid pool 51 and the water pump 52, and a second connecting pipe 55 is connected between the water pump 52 and the nozzle 53. The water pump 52 is used to extract the liquid in the liquid pool 51 and pressurize it, and the The spray head 53 sprays out the liquid column 5 , and the liquid in the liquid column 5 flows back to the liquid pool 51 .

In Fig. 2, the water pump 52 can be, for example, a variable frequency scroll self-priming electric pump with a rated power of 750w, the first connecting pipe 54 can be a latex hose, and the second connecting pipe 55 can be a combination of a metal connecting pipe and a latex hose (wherein the metal connecting pipe is close to the water pump, and the latex hose is close to the nozzle), wherein, the aperture of the latex hose is 3-10mm, the aperture of the metal connecting pipe is 5-15mm, and the nozzle 53 is an aluminum alloy with an aperture of 0.1-1mm. Alloy nozzle.

In the present invention, the terahertz wave radiation source faces terahertz waves with different radiation intensities at different angles in space, and the intensity of the terahertz waves is the largest in the direction where the radiation angle θ is 65°, and the radiation angle θ is defined as follows:

Define the direction of the laser projected from the first off-axis paraboloid to the liquid column as A, and the direction from the liquid column to the device for receiving terahertz waves as B, then the angle between A and B is the radiation angle θ, Define -180°<θ≤180°, define that the radiation angle θ is 0° when A and B are in the same direction, and 180° when A and B are in the opposite direction, and define that the radiation angle θ is 0° and rotates clockwise to The radiation angle θ is positive when the radiation angle θ is 180° between directions, otherwise it is negative. From this definition, we can see that the radiation angle θ in Figure 1 is a positive value. Figure 5 is a numerical distribution diagram of the radiation angle θ from the top view, as shown in Figure 5, on the top view shown in Figure 1, -180°<θ≤180°, when the radiation angle θ is 65°, the terahertz wave The intensity is the largest, as shown in Figure 3 and Figure 4, that is, the terahertz wave corresponding to the radiation angle θ being 65°.

As shown in FIG. 1 , the system for generating high-intensity broadband terahertz waves provided by the present invention may further include a terahertz wave detection system 6, which includes a second off-axis parabolic reflector 61, a silicon wafer 62, a second Three off-axis parabolic mirrors 63, a ZnTe crystal 64, a first convex lens 65, a terahertz wave detector 66 and a second convex lens 67, wherein:

The focal lengths of the second off-axis parabolic mirror 61 and the third off-axis parabolic mirror 63 are 4 inches,

The second off-axis parabolic reflector 61 converges the terahertz wave into a beam of parallel beams, and the parallel beam is filtered by the silicon chip 62 and projected to the third off-axis parabolic reflector 63 to focus and form a focused beam, which is connected with the first The detection beams focused by the two convex lenses 67 are collectively focused on the ZnTe crystal 64 and then pass through the first convex lens 65 , and then the intensity is detected by the terahertz wave detector 66 .

In FIG. 2 , the terahertz wave detector 66 may be, for example, a self-balancing photodetector.

The present invention also provides a method for generating a high-intensity broadband terahertz wave using a liquid column in Fig. 1 and Fig. 2, which includes the following steps:

S1: Laser 1 emits a horizontally polarized laser beam;

S2: The horizontally polarized laser beam is split into a beam of pump light and a beam of probe light after passing through the beam splitter 2;

S3: the pump light is modulated by the chopper 3 and focused on the liquid column 5 through the first off-axis parabolic mirror 4;

S4: A terahertz wave radiation source is formed at the liquid column 5 and radiates high-intensity broadband terahertz waves.

It should be noted that the signal light such as "beam" mentioned in the present invention all propagates in the same horizontal plane, that is, the signal light between any two elements in Figure 1 is in the same horizontal plane, and the generated terahertz Waves are also received in the same horizontal plane.

Fig. 3 is the time-domain waveform of the terahertz wave produced by the present invention, and Fig. 4 is the spectrum diagram of the terahertz wave produced by the present invention, and the time delay in Fig. 3 refers to the pump light and the probe light after passing through the beam splitter 2 The time difference between them can be seen from Figure 3 and Figure 4, the amplitude of the terahertz wave is more than 10 times stronger than the intensity of the terahertz wave generated by pumping air with the same power; The invention can produce a high-intensity broadband terahertz radiation source, which is easy for practical application in spectroscopic measurement and imaging.

The system and method for generating high-intensity broadband terahertz waves provided by the present invention innovatively apply liquid columns to generate terahertz waves and have high generation efficiency. The system is simple in structure, low in construction cost, easy to maintain, and high in stability, making up for At present, there is a blank in the field of high-intensity broadband terahertz wave generation technology, which has strong scientific research and practical application value.

Those skilled in the art can understand that the accompanying drawing is only a schematic diagram of an embodiment, and the modules or processes in the accompanying drawing are not necessarily necessary for implementing the present invention.

Those of ordinary skill in the art can understand that: the modules in the device in the embodiment may be distributed in the device in the embodiment according to the description in the embodiment, or may be changed and located in one or more devices different from the embodiment. The modules in the above embodiments can be combined into one module, and can also be further split into multiple sub-modules.

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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (11)

1. A system that utilizes a liquid column to generate a high-intensity broadband terahertz wave, is characterized in that it includes a laser, a beam splitter, a chopper, a first off-axis parabolic mirror and a liquid column that are sequentially arranged on the optical path, wherein: The focal length of the first off-axis parabolic reflector is 1 inch, The direction of the liquid column is vertically downward, The laser is used to emit a horizontally polarized laser beam, and the horizontally polarized laser beam is divided into a beam of pump light and a beam of probe light after passing through the beam splitter, and the pump light is modulated by the chopper and passed through the first The off-axis parabolic reflector focuses on the liquid column, and a terahertz wave radiation source capable of radiating high-intensity broadband terahertz waves is formed at the liquid column. 2. The system for generating high-intensity broadband terahertz waves by using a liquid column according to claim 1, wherein the laser is a femtosecond laser, and the chopping frequency of the chopper is 100-300 Hz. 3. The system for generating high-intensity broadband terahertz waves using a liquid column according to claim 1, wherein the liquid in the liquid column is water, an inorganic solution or an organic solution. 4. The system for generating high-intensity broadband terahertz waves using a liquid column according to claim 3, wherein the liquid in the liquid column is calcium chloride solution or carbon tetrachloride solution. 5. The system for generating high-intensity broadband terahertz waves using a liquid column according to claim 1, wherein the diameter of the liquid column is 0.2um. 6. The system for generating high-intensity broadband terahertz waves using a liquid column according to claim 1, wherein the liquid column is generated by a liquid column generating device, and the liquid column generating device includes a liquid pool, a water pump, A spray head, a first connecting pipe and a second connecting pipe, the first connecting pipe is connected between the liquid pool and the water pump, the second connecting pipe is connected between the water pump and the spray head, the The water pump is used to draw the liquid in the liquid pool and pressurize it, and spray the liquid column from the spray head, and the liquid in the liquid column returns to the liquid pool. 7. The system for generating high-intensity broadband terahertz waves using a liquid column according to claim 6, wherein the water pump is a variable frequency scroll self-priming electric pump with a rated power of 750w, and the first connecting pipe It is a latex hose, and the second connecting pipe is a combination of a metal connecting pipe and a latex hose, wherein the latex hose has an aperture of 3 to 10 mm, the metal connecting pipe has an aperture of 5 to 15 mm, and the nozzle is an aperture between Aluminum alloy nozzles between 0.1mm and 1mm. 8. The system for generating high-intensity broadband terahertz waves using a liquid column according to claim 1, further comprising a terahertz wave detection system comprising a second off-axis parabolic reflector, a silicon wafer, a third Off-axis parabolic mirror, ZnTe crystal, first convex lens, terahertz wave detector and second convex lens, wherein: The focal lengths of the second off-axis parabolic reflector and the third off-axis parabolic reflector are both 4 inches, The second off-axis parabolic reflector converges the terahertz wave into a parallel beam, which is filtered by the silicon chip and projected to the third off-axis parabolic reflector to focus and form a focused beam. The focused beam The detection beam focused by the second convex lens is jointly focused on the ZnTe crystal and then passes through the first convex lens, and then the intensity is detected by the terahertz wave detector. 9. The system for generating high-intensity broadband terahertz waves using a liquid column according to claim 8, wherein the terahertz wave detector is a self-balancing photodetector. 10. The system for generating high-intensity broadband terahertz waves using a liquid column according to claim 1, wherein the terahertz wave radiation source radiates terahertz waves with different intensities at different angles in space, and the radiation angle θ is 65° direction, the intensity of the terahertz wave is the largest, and the definition of the radiation angle θ is as follows: Define the direction of the laser projected from the first off-axis paraboloid to the liquid column as A, and the direction from the liquid column to the device for receiving terahertz waves as B, then the angle between A and B is the radiation angle θ, Define -180°<θ≤180°, define that the radiation angle θ is 0° when A and B are in the same direction, and 180° when A and B are in the opposite direction, and define that the radiation angle θ is 0° and rotates clockwise to The radiation angle θ is positive when the radiation angle θ is 180° between directions, otherwise it is negative. 11. A method for producing a high-intensity broadband terahertz wave using a liquid column in the system according to any one of claims 1 to 10, characterized in that it comprises the following steps: S1: the laser emits a horizontally polarized laser beam; S2: the horizontally polarized laser beam is divided into a beam of pump light and a beam of probe light after passing through the beam splitter; S3: the pump light is modulated by the chopper and focused on the liquid column through the first off-axis parabolic reflector; S4: A terahertz wave radiation source is formed at the liquid column and radiates high-intensity broadband terahertz waves.