A signal processing method for realizing terahertz frequency up-conversion

Abstract

The present invention belongs to the field of terahertz communication, and specifically relates to a signal processing method for realizing terahertz frequency up-conversion. After the terahertz signal received by the terahertz antenna and the pump laser output by the pump light source generating device are combined by a dichroic mirror, they are collinearly injected into an alkali metal sample cell provided in a heating device. The ultraviolet collimated light mixed with the residual pump laser and the terahertz signal output by the alkali metal sample cell passes through a filter to obtain ultraviolet collimated light. By performing photoelectric detection on the ultraviolet collimated light, signal processing after the frequency up-conversion of the terahertz signal is realized. The device based on this method has a simple structure, the used devices are maturely developed, and the cost is low; moreover, the ultraviolet collimated light and the terahertz signal have consistent time-resolved characteristics, can directly copy all the information carried by the terahertz signal completely, and have a low bit error rate; the ultraviolet detector has extremely high sensitivity, requires a low conversion rate for four-wave mixing, and is easy to realize the frequency up-conversion of the terahertz signal.

Description

Technical Field

[0001] The present invention belongs to the field of terahertz communication, and specifically relates to a signal processing method for realizing terahertz frequency up-conversion. Background Art

[0002] In recent years, with the rapid development of the Internet of Things, the interconnection of various intelligent terminal devices relies on a communication system that can achieve ultra-wideband and ultra-high-speed transmission, which requires a higher carrier frequency to meet the large data volume transmission rate higher than 100 Gbit / s. Currently, the frequency band for high-speed communication is developing from millimeter waves to terahertz frequencies (0.1 - 10 THz), and one of the key technologies is the detection of terahertz signals. At present, relatively common terahertz detection means include semiconductor Schottky diode detectors and superconductor-insulator-superconductor tunneling junction detectors, etc. However, the response frequency bands of these two types of detectors are lower than 2.5 THz, and moreover, in the detection process, it is necessary to cooperate with a terahertz local oscillator for heterodyne detection, the system is complex, and the cost is relatively high; Bolometer is a terahertz detection instrument that is currently used more, but the detection sensitivity of Bolometer is low, and the response speed is slow, which simply cannot meet the requirements of high-speed detection; the widely concerned terahertz quantum well detector can be designed with a response frequency band as needed, can meet the detection of high-frequency terahertz signals, and has a fast response speed and relatively high sensitivity. However, the working environment of the quantum well detector requires cryogenic cooling (<50 K) to maintain, and moreover, the current commercial products are not yet mature.

[0003] If a terahertz signal detection system can be constructed based on commercially available devices at the current level, so as to realize the frequency up-conversion of terahertz signals into wavelengths that are easy to detect, the R & D difficulty of the terahertz detection system can be reduced, the cost scale can be controlled, at the same time, a new method for terahertz signal processing can be provided, and moreover, it can provide a great impetus to the development of the terahertz communication field. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for frequency up-converting terahertz signals into ultraviolet light signals that are easy to detect, which can realize terahertz signal processing based on current commercially available devices, reduce the R & D difficulty, and control the cost scale.

[0005] The technical solution adopted by the present invention to achieve the above object is:

[0006] A signal processing system for realizing terahertz frequency up-conversion, comprising: a terahertz antenna, a pump light source generating device, a dichroic mirror, an alkali metal sample cell, a heating device and a filter mirror. Wherein, the terahertz signal received by the terahertz antenna and the pump laser output by the pump light source generating device are combined by the dichroic mirror and then collinearly enter the alkali metal sample cell arranged in the heating device. The ultraviolet collimated light mixed with the residual pump laser and the terahertz signal output by the alkali metal sample cell passes through the filter mirror to obtain ultraviolet collimated light, and signal processing based on the frequency up-conversion of the terahertz signal is realized by performing photoelectric detection on the ultraviolet collimated light.

[0007] The pump light source generating device is a pump light source.

[0008] The pump light source generating device includes two pump light sources and a dichroic mirror A. The pump lasers emitted by the two pump light sources are combined by the dichroic mirror A so that the combined pump light source is combined with the signal received by the terahertz antenna again.

[0009] The pump light source generating device includes two pump light sources and a polarization beam splitting cube. The pump lasers emitted by the two pump light sources are combined by the polarization beam splitting cube so that the combined pump light source is combined with the signal received by the terahertz antenna again.

[0010] The heating device is a sealed hollow shell, and a transparent window is provided at each of the left and right ends of the shell. The terahertz signal and the pump laser pass through the alkali metal sample cell through the two opposite transparent windows, and a band anti-reflection film is coated on the surface of the transparent window.

[0011] The alkali metal in the alkali metal sample cell includes any one of sodium, potassium, rubidium and cesium.

[0012] A signal processing method for realizing terahertz frequency up-conversion, comprising the following steps:

[0013] The terahertz signal received by the terahertz antenna and the pump laser output by the pump light source generating device are combined by the dichroic mirror and then collinearly enter the alkali metal sample cell arranged in the heating device;

[0014] The heating device heats the alkali metal sample cell to generate alkali metal vapor. The terahertz signal and the pump light source undergo a four-band mixing process with the alkali metal vapor to generate ultraviolet collimated light, which is output together with the residual pump laser and the terahertz signal;

[0015] The ultraviolet collimated light mixed with the residual pump laser and the terahertz signal passes through the filter mirror to filter out the residual pump laser and the terahertz signal. Signal processing based on the frequency up-conversion of the terahertz signal is realized by performing photoelectric detection on the ultraviolet collimated light after filtering out the residual pump laser and the terahertz signal.

[0016] The pump laser emitted by the pump light source generating device excites the alkali metal atoms in the ground state in the alkali metal sample cell to the m 2 D 5 / 2 energy level, and the terahertz signal received by the terahertz antenna excites the alkali metal atoms at the m 2 D 5 / 2 energy level to the n’ 2 P 3 / 2 energy level.

[0017] The pump laser emitted by the pump light source generating device excites the alkali metal atoms in the ground state in the alkali metal sample cell to the m 2 S 1 / 2 energy level, and the terahertz signal received by the terahertz antenna excites the alkali metal atoms at the m 2 S 1 / 2 energy level to the n’ 2 P 3 / 2 energy level.

[0018] The frequency range of the terahertz signal received by the terahertz antenna is: 0.1 - 10.0 THz.

[0019] The present invention has the following beneficial effects and advantages:

[0020] 1. Based on the alkali metal vapor to achieve four-wave mixing, the required device structure is simple, without an optical resonator, and convenient for optical adjustment.

[0021] 2. Commercially available pump light sources at a relatively mature level and subsequent ultraviolet-band photodetectors can be used, which is beneficial to controlling the system cost.

[0022] 3. The ultraviolet collimated light and the terahertz signal have consistent time-resolved characteristics, can directly copy all the information carried by the terahertz signal completely, and have a low error rate.

[0023] 4. The single-photon energy at terahertz frequencies is extremely low, and the sensitivity of terahertz detectors is limited, resulting in high energy requirements for terahertz signals; the single-photon energy in the ultraviolet band is high, two orders of magnitude higher than terahertz frequencies, and the current ultraviolet-band photodetectors have extremely high sensitivity and can achieve single-photon detection of ultraviolet light. Therefore, this method has low requirements for the conversion rate of four-wave mixing and is easy to achieve the terahertz frequency up-conversion and detection functions.

[0024] 5. This method is based on injecting three external signals into the alkali metal cell, and the four-wave mixing process occurs through a unique path. The corresponding ultraviolet collimated light wavelength generated is unique, and there will be no interference problem in the ultraviolet light detection process.

[0025] 6. This method can continuously tune and detect the terahertz signal frequencies within a certain frequency range. Description of the Drawings

[0026] Figure 1 Schematic diagram a of the principle of the present invention;

[0027] Figure 2 Schematic diagram b of the principle of the present invention;

[0028] Figure 3 Schematic diagram c of the principle of the present invention;

[0029] Figure 4 Schematic diagram d of the principle of the present invention;

[0030] Figure 5 Schematic diagram a of the structure of the present invention;

[0031] Figure 6 Schematic diagram b of the structure of the present invention;

[0032] Figure 7 Schematic diagram c of the structure of the present invention;

[0033] Wherein 1 is a terahertz antenna, 2 is a pump light source a, 3 is a pump light source b, 4 is a polarization beam splitting cube, 5 is a dichroic mirror a, 6 is a dichroic mirror b, 7 is an alkali metal sample cell, 8 is a heating device, and 9 is a filter. Specific embodiments

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] Solution 1:

[0036] As Figure 5 , Figure 6 shown, a signal processing method for realizing terahertz frequency up-conversion, the device structure involved includes a terahertz antenna, a pump light source a, a pump light source b, an alkali metal sample cell, a heating device, and a filter.

[0037] The terahertz antenna can receive terahertz signals in space and, through its waveguide structure, collimate the propagation direction of the terahertz signals so that the terahertz signals enter the alkali metal sample cell;

[0038] As Figure 1 , Figure 2 shown, the output laser wavelength of the pump light source a can resonantly excite alkali metal atoms in the ground state (n 2 S 1 / 2 ) to the n 2 P 3 / 2 energy level. The output laser wavelength of the pump light source a has a certain range of tunability and can also non-resonantly excite alkali metal atoms in the ground state to the vicinity of the n 2 P 3 / 2 energy level;

[0039] The output laser wavelength of the pump light source b can resonantly excite alkali metal atoms at the n 2 P 3 / 2 energy level to the m 2 D 5 / 2 energy level. The output laser wavelength of the pump light source b has a certain range of tunability and can also non-resonantly excite alkali metal atoms at the n 2 P 3 / 2 energy level or near it to near the m 2 D 5 / 2 energy level; The terahertz signal received by the terahertz antenna will excite alkali metal atoms at the m 2 D 5 / 2 energy level or near it to the n' 2 P 3 / 2 energy level or near it;

[0040] The output laser wavelength of the pump light source b can also resonantly excite alkali metal atoms at the n 2 P 3 / 2 energy level to the m 2 S 1 / 2 energy level. The output laser wavelength of the pump light source b has a certain range of tunability and can also non-resonantly excite alkali metal atoms at the n 2 P 3 / 2 energy level or near it to near the m 2 S 1 / 2 energy level; The terahertz signal received by the terahertz antenna will excite alkali metal atoms at the m 2 S 1 / 2 energy level or near it to the n' 2 P 3 / 2 energy level or near it;

[0041] The laser output by the pump light source a, the laser output by the pump light source b, and the terahertz signal received by the terahertz antenna are collimated and combined and then enter the alkali metal sample cell collinearly in space. After the alkali metal sample cell is heated, alkali metal vapor atoms with corresponding concentrations are generated inside. Based on the third-order nonlinear polarization of the alkali metal, a four-wave mixing process occurs, generating ultraviolet wavelength collimated light. The laser output by the pump light source a, the laser output by the pump light source b, the terahertz signal, and the generated ultraviolet collimated light participating in the four-wave mixing satisfy energy conservation. The frequency relationship of the ultraviolet collimated light is as shown in formula (1):

[0042] ω(UV) = ω(a) + ω(b) + ω(THz) (1)

[0043] Among them, ω(UV) is the frequency of the ultraviolet collimated light, ω(a) is the output laser frequency of the pump source a, ω(b) is the output laser frequency of the pump source b, and ω(THz) is the frequency of the terahertz signal received by the terahertz antenna.

[0044] Solution 2:

[0045] As Figure 7 shown, the device structure involved in a signal processing method for realizing terahertz frequency up-conversion includes a terahertz antenna, a pump source b, a dichroic mirror, an alkali metal sample cell, a heating device, and a filter.

[0046] The terahertz antenna can receive the terahertz signal in space and, through its waveguide structure, collimate the propagation direction of the terahertz signal to make the terahertz signal enter the alkali metal sample cell;

[0047] As Figure 3 、 Figure 4 shown, the output laser wavelength of the pump source b can resonantly excite alkali metal atoms in the ground state (n 2 S 1 / 2 ) to the m 2 D 5 / 2 energy level through two-photon absorption, and the output laser wavelength of the pump source b has a certain range of tunability and can also non-resonantly excite alkali metal atoms in the ground state (n 2 S 1 / 2 ) to the vicinity of the m 2 D 5 / 2 energy level; the terahertz signal received by the terahertz antenna excites alkali metal atoms in the m 2 D 5 / 2 energy level or its vicinity to the n' 2 P 3 / 2 energy level or its vicinity;

[0048] The output laser wavelength of the pump source b can also resonantly excite alkali metal atoms in the ground state (n 2 S 1 / 2 ) to the m 2 S 1 / 2 energy level through two-photon absorption, and the output laser wavelength of the pump source b has a certain range of tunability and can also non-resonantly excite alkali metal atoms in the ground state (n 2 S 1 / 2 ) to the vicinity of the m 2 S 1 / 2 energy level; the terahertz signal received by the terahertz antenna excites alkali metal atoms in the m 2 S 1 / 2 energy level or its vicinity to the n' 2 P 3 / 2 energy level or its vicinity;

[0049] After the laser output by the pump light source b and the terahertz signal received by the terahertz antenna are collimated and combined, they enter the alkali metal sample cell collinearly in space. After the alkali metal sample cell is heated, alkali metal vapor atoms with a corresponding concentration are generated inside. Based on the third-order nonlinear polarization of the alkali metal, a four-wave mixing process occurs, generating ultraviolet wavelength collimated light. The laser output by the pump light source b (two photons, 2hν), the terahertz signal, and the generated ultraviolet collimated light participating in the four-wave mixing satisfy energy conservation. The frequency relationship of the ultraviolet collimated light is shown in formula (2):

[0050] ω(UV) = 2ω(b) + ω(THz) (2)

[0051] Among them, ω(UV) is the frequency of the ultraviolet collimated light, ω(b) is the frequency of the laser output by the pump light source b, and ω(THz) is the frequency of the terahertz signal received by the terahertz antenna.

[0052] The alkali metal sample cell is filled with a sufficient amount of alkali metal, and the alkali metal is sodium, potassium, rubidium or cesium; the heating device is used to heat the alkali metal sample cell to the required temperature to generate alkali metal vapor with a corresponding concentration;

[0053] The filter lens has a high transmittance for the ultraviolet light band and a high reflectance for the bands other than ultraviolet light;

[0054] The filter lens filters out the residual pump laser and terahertz signal transmitted from the alkali metal sample cell, and only allows the ultraviolet collimated light to pass through. Then, the ultraviolet collimated light is converted into an electrical signal by an ultraviolet band photodetector for subsequent signal processing.

[0055] The laser output by the pump light source a, the laser output by the pump light source b, and the terahertz signal received by the terahertz antenna do not need to be strictly resonant with the alkali metal atomic energy levels. A four-wave mixing process can be achieved within a certain range deviating from the alkali metal atomic energy levels. Correspondingly, the wavelength of the generated ultraviolet collimated light will also change. In this way, the method of the present invention can realize continuous up-conversion of the terahertz signal frequency within a certain frequency range.

[0056] According to when the laser output wavelength of the pump light source and the terahertz signal frequency received by the terahertz antenna are fixed values, since the path of ultraviolet four-wave mixing is unique, the wavelength of the generated ultraviolet collimated light is also unique, and there is no interference problem during the detection of ultraviolet light.

[0057] The ultraviolet collimated light and the terahertz signal have consistent time resolution characteristics, can directly copy all the information carried by the terahertz signal completely, and have a low bit error rate.

[0058] The single - photon energy of ultraviolet light is 2 - 3 orders of magnitude higher than that of terahertz signals, and the sensitivity of ultraviolet photodetectors is extremely high, enabling single - photon detection and reducing the requirements for the four - wave mixing conversion efficiency of the frequency up - conversion system.

[0059] The laser wavelength output by the pump source does not need to be strictly resonant with the terahertz signal frequency received by the terahertz antenna for alkali - metal energy - level transitions. Therefore, the frequency up - conversion system can continuously tune the detection of terahertz signal frequencies within a certain range.

[0060] The wavelength of the pump laser emitted by the pump source in the pump - source generating device is jointly determined by the terahertz signal and the type of alkali metal used in the alkali - metal sample cell. By the terahertz signal frequency, the transition energy levels of the corresponding alkali metal (m 2 D 5 / 2 →n’ 2 P 3 / 2 or m 2 S 1 / 2 →n’ 2 P 3 / 2 ) are determined. After determining the m 2 D 5 / 2 energy level or m 2 S 1 / 2 energy level, the pump - laser wavelength for exciting the alkali - metal atoms from the ground state to the m 2 D 5 / 2 energy level or m 2 S 1 / 2 energy level is then deduced. When the pump - source generating device uses two pump sources, the wavelength of pump source a corresponds to the alkali - metal atom n 2 S 1 / 2 →n 2 P 3 / 2 transition, and the wavelength of pump source b corresponds to the alkali - metal atom n 2 P 3 / 2 →m 2 D 5 / 2 transition or n 2 P 3 / 2 →m 2 S 1 / 2 transition; when the pump - source generating device uses one pump source, half of the pump - source wavelength corresponds to the alkali - metal atom n 2 S 1 / 2 →m 2 D 5 / 2 transition or n 2 P 3 / 2 →m 2 S 1 / 2 transition.

[0061] The following will be combined with Figs. Figure 1 ~Figs. Figure 7, the present invention will be described by specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0062] Embodiment 1

[0063] For the energy level schematic diagram involved in four-wave mixing, please refer to the appendix Figure 1 as shown.

[0064] For the main structure involved in the method of the present invention, please refer to the appendix Figure 5 as shown, including: a terahertz antenna 1, a pump light source a 2, a pump light source b 3, a dichroic mirror a 5, a dichroic mirror b 6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0065] The specific implementation method is as follows:

[0066] The alkali metal sample cell 7 is filled with sodium metal, and the heating device 8 heats the alkali metal sample cell 7 to 300 °C. The saturated vapor pressure of the sodium metal inside the alkali metal sample cell 7 at 300 °C is 1.6×10 -2 torr (2.1 Pa), and the sodium vapor atomic concentration is 2.7×10 14 cm -3 ;

[0067] The pump light source a 2 outputs a laser with a wavelength of 589.2 nm, corresponding to the D2 line of sodium metal. The pump light source b 3 outputs a laser with a wavelength of 419.7 nm. After passing through the dichroic mirror a 5, it is combined with the laser output by the pump source a 2 reflected by the dichroic mirror a 5. The 0.5 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b 6 and is then combined with the pump laser reflected by the dichroic mirror b 6. The laser output by the pump light source a 2, the laser output by the pump light source b 3, and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; antireflection films in the 200 - 900 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; an antireflection film in the 400 - 550 nm band and a high-reflection film in the 580 - 860 nm band are coated on the outer surface of the dichroic mirror a 5; a high-reflection film in the 400 - 860 nm band is coated on the outer surface of the dichroic mirror b 6; the optical thin film coated on the outer surface of the filter 9 only allows the 240 - 250 nm band to pass through;

[0068] The pump light source a 2 outputs 589.2 nm laser to resonantly excite sodium metal atoms in the ground state (3 2 S 1 / 2 ) to the 3 2 P 3 / 2 energy level. The pump light source b 3 outputs 419.7 nm laser to resonantly excite sodium metal atoms in the 3 2 P 3 / 2 energy level to the 13 2 D 5 / 2Energy level, the 0.5 THz signal received by the terahertz antenna 1 will 2 D 5 / 2 energy level of sodium metal atoms is excited to 14 2 P 3 / 2 energy level. Subsequently, through the four-wave mixing process, ultraviolet collimated light of 245.0 nm (14 2 P 3 / 2 →3 2 S 1 / 2 ) is generated. The information carried by the 245.0 nm ultraviolet collimated light is consistent with the information carried by the 0.5 THz signal, achieving complete replication. After the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 245.0 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 0.5 THz signal to 245.0 nm ultraviolet light for information processing.

[0069] Example 2

[0070] The schematic diagram of the energy levels involved in four-wave mixing is shown in the appendix Figure 2 as shown.

[0071] The main structures involved in the method of the present invention are shown in the appendix Figure 6 as shown, including: a terahertz antenna 1, a pump light source a2, a pump light source b3, a polarization beam splitting cube 4, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0072] The specific implementation method is as follows:

[0073] The alkali metal sample cell 7 is filled with sodium metal. The heating device 8 heats the alkali metal sample cell 7 to 300 °C. The saturated vapor pressure of sodium metal inside the alkali metal sample cell 7 at 300 °C is 1.6×10 -2 torr (2.1 Pa), and the sodium vapor atomic concentration is 2.7×10 14 cm -3 ;

[0074] The output laser wavelength of the pump light source a2 is 589.2 nm, corresponding to the D2 line of sodium metal, and the polarization state is S polarization. The output laser wavelength of the pump light source b3 is 442.4 nm, and the polarization state is P polarization. After passing through the polarization beam splitting cube 4, it is combined with the output laser of the pump light source a2 reflected by the polarization beam splitting cube 4. The 6.6 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6 and is then combined with the pump laser reflected by the dichroic mirror b6. The output laser of the pump light source a2, the output laser of the pump light source b3, and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; antireflection films in the 200-900 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; an antireflection film in the 400-860 nm band is coated on the outer surface of the polarization beam splitting cube 4; a high reflection film in the 400-860 nm band is coated on the outer surface of the dichroic mirror b6; the optical film coated on the outer surface of the filter 9 only allows the 245-255 nm band to pass through;

[0075] The 589.2 nm laser output by the pump light source a2 resonantly excites sodium metal atoms in the ground state (3 2 S 1 / 2 ) to the 3 2 P 3 / 2 energy level. The 442.4 nm laser output by the pump light source b3 resonantly excites sodium metal atoms in the 3 2 P 3 / 2 energy level to the 9 2 S 1 / 2 energy level. The 6.6 THz signal received by the terahertz antenna 1 excites sodium metal atoms in the 9 2 S 1 / 2 energy level to the 9 2 P 3 / 2 energy level. Subsequently, ultraviolet collimated light at 251.3 nm (9 2 P 3 / 2 →3 2 S 1 / 2 ) is generated through the four-wave mixing process. The information carried by the 251.3 nm ultraviolet collimated light is consistent with the information carried by the 6.6 THz signal, achieving complete replication; after the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 251.3 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 6.6 THz signal to 251.3 nm ultraviolet light for information processing.

[0076] Example 3

[0077] For the energy level schematic diagram involved in four-wave mixing, please refer to the appendix Figure 2 as shown.

[0078] For the main structures involved in the method of the present invention, please refer to the appendix Figure 5As shown in the figure, it includes: a terahertz antenna 1, a pump light source a 2, a pump light source b 3, a dichroic mirror a 5, a dichroic mirror b 6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0079] The specific implementation method is as follows:

[0080] The alkali metal sample cell 7 is filled with potassium metal. The heating device 8 heats the alkali metal sample cell 7 to 240 °C. The saturated vapor pressure of potassium metal inside the alkali metal sample cell 7 at 240 °C is 4.0×10 -2 torr (5.3 Pa), and the potassium vapor atomic concentration is 7.6×10 14 cm -3 ;

[0081] The pump light source a 2 outputs a laser with a wavelength of 776.7 nm, corresponding to the D2 line of potassium metal. The pump light source b 3 outputs a laser with a wavelength of 475.5 nm. After passing through the dichroic mirror a 5, it is combined with the laser output from the pump light source a 2 reflected by the dichroic mirror a 5. The 2.3 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b 6 and is then combined with the pump laser reflected by the dichroic mirror b 6. The laser output from the pump light source a 2, the laser output from the pump light source b 3, and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; Anti-reflection films with wavelengths in the range of 200 - 900 nm are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; An anti-reflection film with wavelengths in the range of 400 - 550 nm and a high-reflection film with wavelengths in the range of 580 - 860 nm are coated on the outer surface of the dichroic mirror a 5; A high-reflection film with wavelengths in the range of 400 - 860 nm is coated on the outer surface of the dichroic mirror b 6; The optical film coated on the outer surface of the filter 9 only allows wavelengths in the range of 290 - 300 nm to pass through;

[0082] The 776.7 nm laser output from the pump light source a 2 resonantly excites potassium metal atoms in the ground state (4 2 S 1 / 2 ) to the 4 2 P 3 / 2 energy level. The 475.5 nm laser output from the pump light source b 3 resonantly excites potassium metal atoms at the 4 2 P 3 / 2 energy level to the 13 2 S 1 / 2 energy level. The 2.3 THz signal received by the terahertz antenna 1 excites potassium metal atoms at the 13 2 S 1 / 2 energy level to the 13 2 P 3 / 2 energy level. Subsequently, through the four-wave mixing process, 292.8 nm (13 2 P 3 / 2 → 4 2 S 1 / 2) of the ultraviolet collimated light, the information carried by the 292.8 nm ultraviolet collimated light is consistent with the information carried by the 2.3 THz signal, achieving complete replication; after the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 292.8 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 2.3 THz signal to 292.8 nm ultraviolet light and then performing information processing.

[0083] Example 4

[0084] The energy level schematic diagram involved in four-wave mixing is shown in the appendix Figure 1 as shown.

[0085] The main structures involved in the method of the present invention are shown in the appendix Figure 6 as shown, including: a terahertz antenna 1, a pump light source a2, a pump light source b3, a polarization beam splitting cube 4, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0086] The specific implementation method is as follows:

[0087] The alkali metal sample cell 7 is filled with potassium metal, and the heating device 8 heats the alkali metal sample cell 7 to 240 °C. The saturated vapor pressure of the potassium metal inside the alkali metal sample cell 7 at 240 °C is 4.0×10 -2 torr (5.3 Pa), and the potassium vapor atomic concentration is 7.6×10 14 cm -3 ;

[0088] The pump light source a2 outputs a laser with a wavelength of 776.7 nm, corresponding to the D2 line of potassium metal, and the polarization state is S polarization. The pump light source b3 outputs a laser with a wavelength of 466.0 nm, and the polarization state is P polarization. After passing through the polarization beam splitting cube 4, it is combined with the laser output from the pump light source a2 that is reflected by the polarization beam splitting cube 4. The 10.0 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6 and then is combined with the pump laser reflected by the dichroic mirror b6. The laser output from the pump light source a2, the laser output from the pump light source b3, and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; antireflection films in the 200 - 900 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; an antireflection film in the 400 - 860 nm band is coated on the outer surface of the polarization beam splitting cube 4; a high reflection film in the 400 - 860 nm band is coated on the outer surface of the dichroic mirror b6; the optical film coated on the outer surface of the filter 9 only allows the 280 - 290 nm band to pass through;

[0089] The 776.7 nm laser output by the pump light source a2 will be located in the ground state (4 2 S 1 / 2) potassium metal atoms are resonantly excited to 4 2 P 3 / 2 energy level, the pump light source b3 outputs a 466.0 nm laser to resonantly excite the potassium metal atoms at the 4 2 P 3 / 2 energy level to the 15 2 D 5 / 2 energy level, the 10.0 THz signal received by the terahertz antenna 1 will excite the potassium metal atoms at the 15 2 D 5 / 2 energy level to the 27 2 P 3 / 2 energy level, and then through a four-wave mixing process, ultraviolet collimated light of 287.0 nm (27 2 P 3 / 2 →4 2 S 1 / 2 ) is generated. The information carried by the 287.0 nm ultraviolet collimated light is consistent with the information carried by the 10.0 THz signal, realizing complete replication; after the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 287.0 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 10.0 THz signal to 287.0 nm ultraviolet light for information processing.

[0090] Example 5

[0091] The energy level schematic diagram involved in four-wave mixing is shown in the appendix Figure 2 as shown.

[0092] The main structure involved in the method of the present invention is shown in the appendix Figure 6 as shown, including: a terahertz antenna 1, a pump light source a2, a pump light source b3, a polarization beam splitting cube 4, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0093] The specific implementation method is as follows:

[0094] The alkali metal sample cell 7 is filled with rubidium metal, and the heating device 8 heats the alkali metal sample cell 7 to 210 °C. The saturated vapor pressure of rubidium metal inside the alkali metal sample cell 7 at 210 °C is 6.8×10 -2 torr (9.1 Pa), and the rubidium vapor atomic concentration is 1.4×10 15 cm -3 ;

[0095] The pump light source a2 outputs laser with a wavelength of 780.2 nm, corresponding to the D2 line of rubidium metal, and the polarization state is S polarization. The pump light source b3 outputs laser with a wavelength of 481.7 nm, and the polarization state is P polarization. After passing through the polarization beam splitting cube 4, it is combined with the laser output by the pump light source a2 that is reflected by the polarization beam splitting cube 4. The 0.1 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6 and is then combined with the pump laser reflected by the dichroic mirror b6. The laser output by the pump light source a2, the laser output by the pump light source b3, and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; antireflection films in the 200 - 900 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; an antireflection film in the 400 - 860 nm band is coated on the outer surface of the polarization beam splitting cube 4; a high reflection film in the 400 - 860 nm band is coated on the outer surface of the dichroic mirror b6; the optical film coated on the outer surface of the filter 9 only allows the band of 295 - 305 nm to pass through;

[0096] The 780.2 nm laser output by the pump light source a2 resonantly excites rubidium metal atoms in the ground state (5 2 S 1 / 2 ) to the 5 2 P 3 / 2 energy level. The 481.7 nm laser output by the pump light source b3 resonantly excites rubidium metal atoms in the 5 2 P 3 / 2 energy level to the 34 2 S 1 / 2 energy level. The 0.1 THz signal received by the terahertz antenna 1 excites rubidium metal atoms in the 34 2 S 1 / 2 energy level to the 34 2 P 3 / 2 energy level. Subsequently, ultraviolet collimated light of 297.8 nm (34 2 P 3 / 2 →5 2 S 1 / 2 ) is generated through the four-wave mixing process. The information carried by the 297.8 nm ultraviolet collimated light is consistent with the information carried by the 0.1 THz signal, achieving complete replication. After the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 297.8 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 0.1 THz signal to 297.8 nm ultraviolet light for information processing.

[0097] Example 6

[0098] The energy level schematic diagram involved in four-wave mixing is shown in the appendix Figure 1 as shown.

[0099] The main structures involved in the method of the present invention are shown in the appendix Figure 5As shown in the figure, it includes: a terahertz antenna 1, a pump light source a 2, a pump light source b 3, a dichroic mirror a 5, a dichroic mirror b 6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0100] The specific implementation method is as follows:

[0101] The alkali metal sample cell 7 is filled with rubidium metal. The heating device 8 heats the alkali metal sample cell 7 to 210 °C. The saturated vapor pressure of the rubidium metal inside the alkali metal sample cell 7 at 210 °C is 6.8×10 -2 torr (9.1 Pa), and the rubidium vapor atomic concentration is 1.4×10 15 cm -3 ;

[0102] The pump light source a 2 outputs a laser with a wavelength of 780.2 nm, corresponding to the D2 line of rubidium metal. The pump light source b 3 outputs a laser with a wavelength of 502.3 nm. After passing through the dichroic mirror a 5, it is combined with the laser output by the pump source a 2 reflected by the dichroic mirror a 5. The 7.4 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b 6 and is then combined with the pump laser reflected by the dichroic mirror b 6. The laser output by the pump light source a 2, the laser output by the pump light source b 3, and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; Anti-reflection films with a wavelength range of 200 - 900 nm are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; An anti-reflection film with a wavelength range of 400 - 550 nm and a high-reflection film with a wavelength range of 580 - 860 nm are coated on the outer surface of the dichroic mirror a 5; A high-reflection film with a wavelength range of 400 - 860 nm is coated on the outer surface of the dichroic mirror b 6; The optical thin film coated on the outer surface of the filter 9 only allows light with a wavelength range of 300 - 310 nm to pass through;

[0103] The 780.2 nm laser output by the pump light source a 2 resonantly excites rubidium metal atoms in the ground state (5 2 S 1 / 2 ) to the 5 2 P 3 / 2 energy level. The 502.3 nm laser output by the pump light source b 3 resonantly excites rubidium metal atoms in the 5 2 P 3 / 2 energy level to the 12 2 D 5 / 2 energy level. The 7.4 THz signal received by the terahertz antenna 1 excites rubidium metal atoms in the 12 2 D 5 / 2 energy level to the 15 2 P 3 / 2 energy level. Subsequently, through the four-wave mixing process, 303.3 nm (15 2 P 3 / 2 → 5 2 S 1 / 2) The ultraviolet collimated light, the information carried by the 303.3nm ultraviolet collimated light is consistent with the information carried by the 7.4THz signal, achieving complete replication; after the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 303.3nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 7.4THz signal to 303.3nm ultraviolet light for information processing.

[0104] Example 7

[0105] The energy level schematic diagram involved in four-wave mixing is shown in the appendix Figure 1 as shown.

[0106] The main structures involved in the method of the present invention are shown in the appendix Figure 6 as shown, including: a terahertz antenna 1, a pump light source a2, a pump light source b3, a polarization beam splitting cube 4, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0107] The specific implementation method is as follows:

[0108] The alkali metal sample cell 7 is filled with cesium metal, and the heating device 8 heats the alkali metal sample cell 7 to 200 °C. The saturated vapor pressure of cesium metal inside the alkali metal sample cell 7 at 200 °C is 8.9×10 -2 torr (11.9 Pa), and the cesium vapor atomic concentration is 1.8×10 15 cm -3 ;

[0109] The pump light source a2 outputs a laser with a wavelength of 852.3nm, corresponding to the D2 line of cesium metal, and the polarization state is S polarization. The pump light source b3 outputs a laser with a wavelength of 517.7nm, and the polarization state is P polarization. After passing through the polarization beam splitting cube 4, it is combined with the laser output from the pump light source a2 reflected by the polarization beam splitting cube 4. The 1.0THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6 and is then combined with the pump laser reflected by the dichroic mirror b6. The laser output from the pump light source a2, the laser output from the pump light source b3, and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; the outer surfaces of the windows at both ends of the alkali metal sample cell 7 are coated with an antireflection film in the 200-900nm band; the outer surface of the polarization beam splitting cube 4 is coated with an antireflection film in the 400-860nm band; the outer surface of the dichroic mirror b6 is coated with a high reflection film in the 400-860nm band; the optical thin film coated on the outer surface of the filter 9 only allows the 315-325nm band to pass through;

[0110] The pump light source a2 outputs 852.3nm laser, which will be located in the ground state (6 2 S 1 / 2) cesium metal atoms are resonantly excited to 6 2 P 3 / 2 energy level, the pump light source b3 outputs a 517.7 nm laser to resonantly excite the cesium metal atoms located at the 6 2 P 3 / 2 energy level to 20 2 D 5 / 2 energy level, the 1.0 THz signal received by the terahertz antenna 1 will excite the cesium metal atoms at the 20 2 D 5 / 2 energy level to 22 2 P 3 / 2 energy level, and then through a four-wave mixing process, ultraviolet collimated light of 321.7 nm (22 2 P 3 / 2 →6 2 S 1 / 2 ) is generated. The information carried by the 321.7 nm ultraviolet collimated light is consistent with the information carried by the 1.0 THz signal, realizing complete replication; after the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 321.7 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 1.0 THz signal to 321.7 nm ultraviolet light for information processing.

[0111] Example 8

[0112] The schematic diagram of the energy levels involved in four-wave mixing is shown in the appendix Figure 2 as shown.

[0113] The main structures involved in the method of the present invention are shown in the appendix Figure 5 as shown, including: a terahertz antenna 1, a pump light source a2, a pump light source b3, a dichroic mirror a5, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0114] The specific implementation method is as follows:

[0115] The alkali metal sample cell 7 is filled with cesium metal, and the heating device 8 heats the alkali metal sample cell 7 to 200 °C. The saturated vapor pressure of the cesium metal inside the alkali metal sample cell 7 at 200 °C is 8.9×10 -2 torr (11.9 Pa), and the cesium vapor atomic concentration is 1.8×10 15 cm -3 ;

[0116] The pump light source a2 outputs laser with a wavelength of 852.3 nm, corresponding to the D2 line of cesium metal. The pump light source b3 outputs laser with a wavelength of 546.3 nm. After passing through the dichroic mirror a5, it is combined with the laser output by the pump light source a2 that is reflected by the dichroic mirror a5. The 4.1 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6 and is then combined with the pump laser that is reflected by the dichroic mirror b6. The laser output by the pump light source a2, the laser output by the pump light source b3, and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; antireflection films in the 200 - 900 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; an antireflection film in the 400 - 550 nm band and a high-reflection film in the 580 - 860 nm band are coated on the outer surface of the dichroic mirror a5; a high-reflection film in the 400 - 860 nm band is coated on the outer surface of the dichroic mirror b6; the optical thin film coated on the outer surface of the filter 9 only allows light in the 325 - 335 nm band to pass through;

[0117] The pump light source a2 outputs 852.3 nm laser, which resonantly excites cesium metal atoms in the ground state (6 2 S 1 / 2 ) to the 6 2 P 3 / 2 energy level. The pump light source b3 outputs 546.3 nm laser, which resonantly excites cesium metal atoms in the 6 2 P 3 / 2 energy level to the 13 2 S 1 / 2 energy level. The 4.1 THz signal received by the terahertz antenna 1 excites cesium metal atoms in the 13 2 S 1 / 2 energy level to the 13 2 P 3 / 2 energy level. Subsequently, ultraviolet collimated light at 331.4 nm (13 2 P 3 / 2 →6 2 S 1 / 2 ) is generated through the four-wave mixing process. The information carried by the 331.4 nm ultraviolet collimated light is consistent with the information carried by the 4.1 THz signal, achieving complete replication. After the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 331.4 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 4.1 THz signal to 331.4 nm ultraviolet light for information processing.

[0118] Example 9

[0119] The energy level schematic diagram involved in four-wave mixing is shown in the appendix Figure 3 as shown.

[0120] The main structures involved in the method of the present invention are shown in the appendix Figure 7As shown, it includes: a terahertz antenna 1, a pump light source b3, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0121] The specific implementation method is as follows:

[0122] The alkali metal sample cell 7 is filled with sodium metal. The heating device 8 heats the alkali metal sample cell 7 to 300 °C. The saturated vapor pressure of the sodium metal inside the alkali metal sample cell 7 at 300 °C is 1.6×10 -2 torr (2.1 Pa), and the sodium vapor atomic concentration is 2.7×10 14 cm -3 ;

[0123] The pump light source b3 outputs a laser with a wavelength of 498.9 nm. The 1.4 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6, and then is combined with the pump laser reflected by the dichroic mirror b6. The laser output by the pump light source b3 and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; Anti-reflection films with a wavelength range of 200 - 700 nm are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; A high-reflection film with a wavelength range of 400 - 700 nm is coated on the outer surface of the dichroic mirror b6; The optical thin film coated on the outer surface of the filter 9 only allows light in the wavelength range of 245 - 255 nm to pass through;

[0124] The 498.9 nm laser output by the pump light source b3 resonantly excites the sodium metal atoms in the ground state (3 2 S 1 / 2 ) to the 9 2 D 5 / 2 energy level through two-photon absorption (2hν). The 1.4 THz signal received by the terahertz antenna 1 excites the sodium metal atoms at the 9 2 D 5 / 2 energy level to the 10 2 P 3 / 2 energy level. Subsequently, ultraviolet collimated light at 249.1 nm (10 2 P 3 / 2 →3 2 S 1 / 2 ) is generated through a four-wave mixing process. The information carried by the 249.1 nm ultraviolet collimated light is consistent with the information carried by the 1.4 THz signal, achieving complete replication; After the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 249.1 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 1.4 THz signal to 249.1 nm ultraviolet light for information processing.

[0125] Example 10

[0126] The energy level schematic diagram involved in four-wave mixing is shown in the appendix Figure 4 as follows.

[0127] The main structure involved in the method of the present invention is shown in the appendix Figure 7 as follows, including: a terahertz antenna 1, a pump light source b3, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0128] The specific implementation method is as follows:

[0129] The alkali metal sample cell 7 is filled with sodium metal, and the heating device 8 heats the alkali metal sample cell 7 to 300 °C. The saturated vapor pressure of the sodium metal inside the alkali metal sample cell 7 at 300 °C is 1.6×10 -2 torr (2.1 Pa), and the sodium vapor atomic concentration is 2.7×10 14 cm -3 ;

[0130] The laser wavelength output by the pump light source b3 is 496.6 nm. The 8.8 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6, and then is combined with the pump laser reflected by the dichroic mirror b6. The laser output by the pump light source b3 and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; antireflection films in the 200 - 700 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; a high-reflection film in the 400 - 700 nm band is coated on the outer surface of the dichroic mirror b6; the optical film coated on the outer surface of the filter 9 only allows the 240 - 250 nm band to pass through;

[0131] The 496.6 nm laser output by the pump light source b3 resonantly excites the sodium metal atoms in the ground state (3 2 S 1 / 2 ) to the 11 2 S 1 / 2 energy level through two-photon absorption (2hν). The 8.8 THz signal received by the terahertz antenna 1 excites the sodium metal atoms in the 11 2 S 1 / 2 energy level to the 12 2 P 3 / 2 energy level. Subsequently, through the four-wave mixing process, 246.5 nm (12 2 P 3 / 2 →3 2 S 1 / 2) of the ultraviolet collimated light, the information carried by the 246.5 nm ultraviolet collimated light is consistent with the information carried by the 8.8 THz signal, achieving complete replication; after the filter 9 filters out the residual pump laser and terahertz signal in the output optical signal of the alkali metal sample cell 7, only the 246.5 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet optical signal is photoelectrically detected, thereby realizing the frequency up-conversion of the 8.8 THz signal to 246.5 nm ultraviolet light for information processing.

[0132] Example 11

[0133] The energy level diagram involved in four-wave mixing is shown in the appendix Figure 4 as shown.

[0134] The main structures involved in the method of the present invention are shown in the appendix Figure 7 as shown, including: a terahertz antenna 1, a pump light source b3, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0135] The specific implementation method is as follows:

[0136] The alkali metal sample cell 7 is filled with potassium metal, and the heating device 8 heats the alkali metal sample cell 7 to 240 °C. The saturated vapor pressure of the potassium metal inside the alkali metal sample cell 7 at 240 °C is 4.0×10 -2 torr (5.3 Pa), and the potassium vapor atomic concentration is 7.6×10 14 cm -3 ;

[0137] The pump light source b3 outputs a laser with a wavelength of 590.5 nm. The 3.0 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6 and is then combined with the pump laser reflected by the dichroic mirror b6. The pump laser output by the pump light source b3 and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; the outer surfaces of the windows at both ends of the alkali metal sample cell 7 are coated with an antireflection film in the 200 - 700 nm band; the outer surface of the dichroic mirror b6 is coated with a high-reflection film in the 400 - 700 nm band; the optical film coated on the outer surface of the filter 9 only allows the 290 - 300 nm band to pass through;

[0138] The pump light source b3 outputs a 590.5 nm laser, and through two-photon absorption (2hν), the potassium metal atoms in the ground state (4 2 S 1 / 2 ) are resonantly excited to the 12 2 S 1 / 2 energy level. The 3.0 THz signal received by the terahertz antenna 1 excites the potassium metal atoms at the 12 2 S 1 / 2 energy level to the 12 2 P 3 / 2Energy levels, and then ultraviolet collimated light of 294.4 nm (12 2 P 3 / 2 →4 2 S 1 / 2 ) is generated through the four-wave mixing process. The information carried by the 294.4 nm ultraviolet collimated light is consistent with the information carried by the 3.0 THz signal, achieving complete replication. After the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 294.4 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet optical signal is photoelectrically detected, thus realizing the frequency up-conversion of the 3.0 THz signal to 294.4 nm ultraviolet light for information processing.

[0139] Example 12

[0140] For the schematic diagram of the energy levels involved in four-wave mixing, see the appendix Figure 3 as shown.

[0141] For the main structures involved in the method of the present invention, see the appendix Figure 7 as shown, including: a terahertz antenna 1, a pump light source b3, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0142] The specific implementation method is as follows:

[0143] The alkali metal sample cell 7 is filled with potassium metal. The heating device 8 heats the alkali metal sample cell 7 to 240 °C. The saturated vapor pressure of potassium metal inside the alkali metal sample cell 7 at 240 °C is 4.0×10 -2 torr (5.3 Pa), and the potassium vapor atomic concentration is 7.6×10 14 cm -3 ;

[0144] The laser output by the pump light source b3 has a wavelength of 579.6 nm. The 7.2 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6 and is then combined with the pump laser reflected by the dichroic mirror b6. The laser output by the pump light source b3 and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly. Anti-reflection films in the 200 - 700 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; a high-reflection film in the 400 - 700 nm band is coated on the outer surface of the dichroic mirror b6; the optical film coated on the outer surface of the filter 9 only allows the 285 - 295 nm band to pass through;

[0145] The 579.6 nm laser output by the pump light source b3 resonantly excites potassium metal atoms in the ground state (4 2 S 1 / 2 ) to 15 2 D 5 / 2Energy level, the 7.2 THz signal received by the terahertz antenna 1 will excite potassium metal atoms at the 15 2 D 5 / 2 energy level to the 22 2 P 3 / 2 energy level. Subsequently, through the four-wave mixing process, ultraviolet collimated light at 287.8 nm (22 2 P 3 / 2 →4 2 S 1 / 2 ) is generated. The information carried by the 287.8 nm ultraviolet collimated light is consistent with the information carried by the 7.2 THz signal, achieving complete replication. After the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 287.8 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 7.2 THz signal to 287.8 nm ultraviolet light for information processing.

[0146] Example 13

[0147] For the schematic diagram of the energy levels involved in four-wave mixing, see the appendix Figure 3 as shown.

[0148] For the main structures involved in the method of the present invention, see the appendix Figure 7 as shown, including: a terahertz antenna 1, a pump light source b3, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0149] The specific implementation method is as follows:

[0150] The alkali metal sample cell 7 is filled with rubidium metal. The heating device 8 heats the alkali metal sample cell 7 to 210 °C. The saturated vapor pressure of rubidium metal inside the alkali metal sample cell 7 at 210 °C is 6.8×10 -2 torr (9.1 Pa), and the rubidium vapor atomic concentration is 1.4×10 15 cm -3 ;

[0151] The pump light source b3 outputs laser with a wavelength of 615.1 nm. The 4.6 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6 and is then combined with the pump laser reflected by the dichroic mirror b6. The pump laser output by the pump light source b3 and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly. The outer surfaces of the windows at both ends of the alkali metal sample cell 7 are coated with an antireflection film in the 200 - 700 nm band; the outer surface of the dichroic mirror b6 is coated with a high-reflection film in the 400 - 700 nm band; the optical film coated on the outer surface of the filter 9 only allows the 300 - 310 nm band to pass through;

[0152] The pump light source b3 outputs a 615.1 nm laser, and through two-photon absorption (2hν), rubidium metal atoms in the ground state (5 2 S 1 / 2 ) are resonantly excited to the 11 2 D 5 / 2 energy level. The 4.6 THz signal received by the terahertz antenna 1 excites rubidium metal atoms in the 11 2 D 5 / 2 energy level to the 13 2 P 3 / 2 energy level. Subsequently, ultraviolet collimated light at 306.1 nm (13 2 P 3 / 2 →5 2 S 1 / 2 ) is generated through a four-wave mixing process. The information carried by the 306.1 nm ultraviolet collimated light is consistent with the information carried by the 4.6 THz signal, achieving complete replication. After the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 306.1 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet optical signal is photoelectrically detected, thus realizing the frequency up-conversion of the 4.6 THz signal to 306.1 nm ultraviolet light for information processing.

[0153] Example 14

[0154] The energy level schematic diagram involved in four-wave mixing is shown in the appendix Figure 4 as shown.

[0155] The main structures involved in the method of the present invention are shown in the appendix Figure 7 as shown, including: a terahertz antenna 1, a pump light source b3, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0156] The specific implementation method is as follows:

[0157] The alkali metal sample cell 7 is filled with rubidium metal. The heating device 8 heats the alkali metal sample cell 7 to 210 °C. The saturated vapor pressure of rubidium metal inside the alkali metal sample cell 7 at 210 °C is 6.8×10 -2 torr (9.1 Pa), and the rubidium vapor atom concentration is 1.4×10 15 cm -3 ;

[0158] The pump light source b3 outputs laser with a wavelength of 610.5 nm. The 9.4 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6, and then is combined with the pump laser reflected by the dichroic mirror b6. The laser output by the pump light source b3 and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; antireflection films in the 200 - 700 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; a high-reflection film in the 400 - 700 nm band is coated on the outer surface of the dichroic mirror b6; the optical thin film coated on the outer surface of the filter 9 only allows light in the 300 - 310 nm band to pass through;

[0159] The 610.5 nm laser output by the pump light source b3 resonantly excites rubidium metal atoms in the ground state (5 2 S 1 / 2 ) to the 14 2 S 1 / 2 energy level through two-photon absorption (2hν). The 9.4 THz signal received by the terahertz antenna 1 excites rubidium metal atoms in the 14 2 S 1 / 2 energy level to the 16 2 P 3 / 2 energy level. Subsequently, ultraviolet collimated light at 302.3 nm (16 2 P 3 / 2 →5 2 S 1 / 2 ) is generated through a four-wave mixing process. The information carried by the 302.3 nm ultraviolet collimated light is consistent with the information carried by the 9.4 THz signal, achieving complete replication; after the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 302.3 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thereby realizing the frequency up-conversion of the 9.4 THz signal to 302.3 nm ultraviolet light for information processing.

[0160] Example 15

[0161] For the energy level schematic diagram involved in four-wave mixing, see the appendix Figure 4 as shown.

[0162] For the main structures involved in the method of the present invention, see the appendix Figure 7 as shown, including: a terahertz antenna 1, a pump light source b3, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter 9.

[0163] The specific implementation method is as follows:

[0164] The alkali metal sample cell 7 is filled with cesium metal. The heating device 8 heats the alkali metal sample cell 7 to 200 °C. The saturated vapor pressure of cesium metal inside the alkali metal sample cell 7 at 200 °C is 8.9×10 -2torr (11.9 Pa), the cesium vapor atomic concentration is 1.8×10 15 cm -3 ;

[0165] The laser wavelength output by the pump light source b3 is 640.4 nm. The 0.2 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6, and then is combined with the pump laser reflected by the dichroic mirror b6. The laser output by the pump light source b3 and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; antireflection films in the 200 - 700 nm band are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; a high - reflection film in the 400 - 700 nm band is coated on the outer surface of the dichroic mirror b6; the optical thin film coated on the outer surface of the filter mirror 9 only allows the 315 - 325 nm band to pass through;

[0166] The 640.4 nm laser output by the pump light source b3 resonantly excites cesium metal atoms in the ground state (6 2 S 1 / 2 ) to the 29 2 S 1 / 2 energy level through two - photon absorption (2hν). The 0.2 THz signal received by the terahertz antenna 1 excites cesium metal atoms in the 29 2 S 1 / 2 energy level to the 29 2 P 3 / 2 energy level. Subsequently, ultraviolet collimated light at 320.1 nm (29 2 P 3 / 2 →6 2 S 1 / 2 ) is generated through a four - wave mixing process. The information carried on the 320.1 nm ultraviolet collimated light is consistent with the information carried on the 0.2 THz signal, achieving complete replication; after the filter mirror 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 320.1 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up - conversion of the 0.2 THz signal to 320.1 nm ultraviolet light for information processing.

[0167] Example 16

[0168] The energy - level schematic diagram involved in four - wave mixing is shown in detail in Appendix Figure 3 as shown.

[0169] The main structures involved in the method of the present invention are shown in detail in Appendix Figure 7 as shown, including: a terahertz antenna 1, a pump light source b3, a dichroic mirror b6, an alkali metal sample cell 7, a heating device 8, and a filter mirror 9.

[0170] The specific implementation method is as follows:

[0171] The alkali metal sample cell 7 is filled with cesium metal. The heating device 8 heats the alkali metal sample cell 7 to 200 °C. The saturated vapor pressure of the cesium metal inside the alkali metal sample cell 7 at 200 °C is 8.9×10 -2 torr (11.9 Pa), and the cesium vapor atomic concentration is 1.8×10 15 cm -3 ;

[0172] The pump light source b3 outputs a laser with a wavelength of 654.0 nm. The 6.5 THz signal received by the terahertz antenna 1 passes through the dichroic mirror b6, and then is combined with the pump laser reflected by the dichroic mirror b6. The laser output by the pump light source b3 and the terahertz signal received by the terahertz antenna 1 enter the alkali metal sample cell 7 collinearly; Anti-reflection films with a wavelength range of 200 - 700 nm are coated on the outer surfaces of the windows at both ends of the alkali metal sample cell 7; A high-reflection film with a wavelength range of 400 - 700 nm is coated on the outer surface of the dichroic mirror b6; The optical thin film coated on the outer surface of the filter 9 only allows the wavelength range of 320 - 330 nm to pass through;

[0173] The 654.0 nm laser output by the pump light source b3 resonantly excites cesium metal atoms in the ground state (6 2 S 1 / 2 ) to the 14 2 D 5 / 2 energy level through two-photon absorption (2hν). The 6.5 THz signal received by the terahertz antenna 1 excites cesium metal atoms in the 14 2 D 5 / 2 energy level to the 17 2 P 3 / 2 energy level. Subsequently, ultraviolet collimated light at 324.7 nm (17 2 P 3 / 2 →6 2 S 1 / 2 ) is generated through the four-wave mixing process. The information carried by the 324.7 nm ultraviolet collimated light is consistent with the information carried by the 6.5 THz signal, achieving complete replication; After the filter 9 filters out the residual pump laser and terahertz signal in the optical signal output from the alkali metal sample cell 7, only the 324.7 nm ultraviolet collimated light is allowed to pass through, and then the ultraviolet light signal is photoelectrically detected, thus realizing the frequency up-conversion of the 6.5 THz signal to 324.7 nm ultraviolet light for information processing.

Claims

1. A signal processing system for realizing terahertz frequency up-conversion, characterized in that, Including: A terahertz antenna, a pump light source generating device, a dichroic mirror, an alkali metal sample cell, a heating device, and a filter. Among them, the terahertz signal received by the terahertz antenna and the pump laser output by the pump light source generating device are combined by the dichroic mirror and then collinearly enter the alkali metal sample cell arranged in the heating device. The ultraviolet collimated light mixed with the residual pump laser and the terahertz signal output by the alkali metal sample cell passes through the filter to obtain ultraviolet collimated light. By performing photoelectric detection on the ultraviolet collimated light, signal processing based on the frequency up-conversion of the terahertz signal is realized.

2. The signal processing system for realizing terahertz frequency up-conversion according to claim 1, wherein, The pump light source generating device is a single pump light source.

3. The signal processing system for realizing terahertz frequency up-conversion according to claim 1, wherein, The pump light source generating device includes two pump light sources and a dichroic mirror A. The pump lasers emitted by the two pump light sources are combined by the dichroic mirror A so that the combined pump light source is combined with the signal received by the terahertz antenna again.

4. A signal processing system for realizing terahertz frequency up-conversion according to claim 1, wherein The pump light source generating device includes two pump light sources and a polarization beam splitting cube. The pump lasers emitted by the two pump light sources are combined by the polarization beam splitting cube so that the combined pump light source is combined with the signal received by the terahertz antenna again.

5. A signal processing system for realizing terahertz frequency up-conversion according to claim 1, characterized in that The heating device is a sealed hollow shell, and a transparent window is provided at each of the left and right ends of the shell. The terahertz signal and the pump laser pass through the alkali metal sample cell through the two opposite transparent windows, and the surface of the transparent window is coated with an anti-reflection film in a certain wavelength band.

6. The signal processing system for realizing terahertz frequency up-conversion according to claim 1, characterized in that The alkali metal in the alkali metal sample cell includes any one of sodium, potassium, rubidium, and cesium.

7. A signal processing method for realizing terahertz frequency up-conversion, characterized in that, Including the following steps: The terahertz signal received by the terahertz antenna and the pump laser output by the pump light source generating device are combined by the dichroic mirror and then collinearly enter the alkali metal sample cell arranged in the heating device; The heating device heats the alkali metal sample cell to generate alkali metal vapor. The terahertz signal and the pump light source undergo a four-band mixing process with the alkali metal vapor to generate ultraviolet collimated light, which is output together with the residual pump laser and the terahertz signal; The ultraviolet collimated light mixed with the residual pump laser and the terahertz signal passes through the filter to filter out the residual pump laser and the terahertz signal. By performing photoelectric detection on the ultraviolet collimated light after filtering out the residual pump laser and the terahertz signal, signal processing based on the frequency up-conversion of the terahertz signal is realized.

8. A signal processing method for realizing terahertz frequency up-conversion according to claim 7, characterized in that The pump laser emitted by the pump light source device excites the alkali metal atoms in the ground state in the alkali metal sample cell to the m 2 D 5 / 2 energy level, and the terahertz signal received by the terahertz antenna excites the alkali metal atoms at the m 2 D 5 / 2 energy level to the n' 2 P 3 / 2 energy level. The value range of the variable m is: m > n, and m is an integer. The value range of the variable n' is: n' ≥ m, and n' is an integer.

9. A signal processing method for realizing terahertz frequency up-conversion according to claim 7, characterized in that, The pump laser emitted by the pump light source device excites the alkali metal atoms in the ground state in the alkali metal sample cell to the m 2 S 1 / 2 energy level, and the terahertz signal received by the terahertz antenna excites the alkali metal atoms at the m 2 S 1 / 2 energy level to the n' 2 P 3 / 2 energy level.

10. A signal processing method for realizing terahertz frequency up-conversion according to claim 7, characterized in that, The frequency range of the terahertz signal received by the terahertz antenna is: 0.1 - 10.0 THz.

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