A terahertz wave transmitter and its preparation method

Abstract

The present application discloses a terahertz wave emitter and a preparation method thereof, relating to the technical field of terahertz optoelectronic devices. The terahertz wave emitter comprises a laser source and a first quartz single crystal and a second quartz single crystal pasted together, both of which have a crystal plane index of (0001). By setting the first quartz single crystal at a first target azimuth angle and the second quartz single crystal at a second target azimuth angle, and rotating the second target azimuth angle by 60°, 180°, or 300° relative to the first target azimuth angle, under the excitation of a femtosecond laser with a polarization direction, the terahertz wave peaks of the first quartz single crystal and the second quartz single crystal with the same polarity have the same phase, so that the terahertz wave peaks of the first quartz single crystal and the second quartz single crystal with the same polarity are superimposed, extending the effective phase matching length, and significantly improving the intensity of the terahertz wave finally generated. The emitter has a simple structure, a simple preparation method, and low cost.

Description

Technical Field

[0001] The present application relates to the technical field of terahertz optoelectronic devices, and in particular to a terahertz wave emitter and a preparation method thereof. Background Art

[0002] Terahertz waves are generally defined as electromagnetic waves with frequencies between 0.1 THz and 10 THz. The frequency range covered by terahertz waves is also known as the "Terahertz gap." Due to their unique wavelength range, terahertz waves possess many excellent properties, such as penetrability, safety, and fingerprint resistance, making them of great significance in the research of materials science and physical science. Because terahertz waves lie between microwaves and infrared waves, they are difficult to generate and detect using traditional electronic and photonic methods. Consequently, for many years, research on electromagnetic waves in this band was limited. In recent years, with advances in ultrafast laser technology and high-precision circuit processing, terahertz technology has experienced rapid development.

[0003] Generation and detection are key components in terahertz technology, making terahertz wave emitters crucial components in terahertz systems. Existing photonic methods for generating terahertz waves include photoconductivity and optical rectification. The photoconductivity method exploits the photoelectric effect, irradiating light onto a semiconductor material to excite carriers. Driven by a bias electric field, these carriers accelerate and generate terahertz radiation. Photoconductive antennas are key devices for generating terahertz waves using this method. However, inherent phonon absorption in photoconductive antenna technology limits the intensity and bandwidth of the generated terahertz waves, and photoconductive antennas are expensive to manufacture. Optical rectification utilizes ultrashort laser pulses incident on a nonlinear crystal, exploiting the nonlinear effects of the crystal to generate terahertz pulses. However, phase matching between the excitation light and the generated terahertz light within the nonlinear crystal can significantly affect the bandwidth and intensity of the generated terahertz waves.

[0004] Existing electronic methods for generating terahertz waves, such as novel spintronics-based terahertz wave emitters, utilize femtosecond laser pulses to excite spin electrons in materials, generating terahertz waves through the interaction and propagation of these spin electrons. Compared to these novel spintronics-based terahertz wave emitters, optical rectification methods, which utilize the nonlinear effects of nonlinear crystals, are simpler to generate terahertz waves and produce higher-intensity terahertz waves. However, overcoming the phase matching issues of nonlinear crystals in terahertz wave emitters to enhance terahertz wave intensity remains a pressing technical challenge for those skilled in the art. Summary of the Invention

[0005] To solve the above technical problems, the embodiments of the present application provide a terahertz wave emitter and a preparation method thereof, which achieves this by stacking and pasting two quartz single crystals together and controlling the azimuth angles of the two quartz single crystals so that the peaks of the terahertz waves with the same polarity generated by the femtosecond laser passing through the two quartz single crystals are in phase, thereby extending the effective phase matching length and significantly improving the intensity of the generated terahertz waves.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] A terahertz wave transmitter, comprising:

[0008] A laser source, configured to generate a femtosecond laser, wherein the femtosecond laser has a polarization direction;

[0009] A first quartz single crystal wafer and a second quartz single crystal wafer, wherein the crystal plane index of the first quartz single crystal wafer and the second quartz single crystal wafer are both (0001), and the first quartz single crystal wafer and the second quartz single crystal wafer are bonded together;

[0010] The first quartz single crystal wafer is at a first target azimuth angle, and the second quartz single crystal wafer is at a second target azimuth angle, and the second target azimuth angle is rotated 60°, 180°, or 300° relative to the first target azimuth angle; when the quartz single crystal wafer with a crystal plane index of (0001) is at the target azimuth angle, after the femtosecond laser generated by the laser source is vertically incident on the surface of the quartz single crystal wafer, the terahertz wave amplitude generated by the quartz single crystal wafer is the largest, and the target azimuth angle has a period of 120° within 360° in the plane, and the target azimuth angle includes the first target azimuth angle and the second target azimuth angle.

[0011] Optionally, the thickness of the first quartz single crystal sheet is less than 0.3 mm, and the thickness of the second quartz single crystal sheet is less than 0.3 mm.

[0012] Optionally, the thickness of the first quartz single crystal sheet is equal to the thickness of the second quartz single crystal sheet.

[0013] Optionally, the shape of the first quartz single crystal sheet is the same as the shape of the second quartz single crystal sheet.

[0014] Optionally, the first quartz single crystal wafer and the second quartz single crystal wafer are bonded together using acetone liquid.

[0015] Optionally, the surface of the first quartz single crystal wafer facing away from the second quartz single crystal wafer and the surface of the first quartz single crystal wafer facing the second quartz single crystal wafer are both polished surfaces;

[0016] The surface of the second quartz single crystal wafer facing away from the first quartz single crystal wafer and the surface of the second quartz single crystal wafer facing the first quartz single crystal wafer are both polished surfaces.

[0017] Optionally, the first quartz single crystal wafer and the second quartz single crystal wafer are both α-quartz single crystal wafers.

[0018] A method for preparing a terahertz wave transmitter, comprising:

[0019] Providing a laser source, wherein the laser source is used to generate femtosecond laser light, wherein the femtosecond laser light has a polarization direction;

[0020] Providing a first quartz single crystal wafer and a second quartz single crystal wafer, wherein the crystal plane index of the first quartz single crystal wafer and the second quartz single crystal wafer are both (0001);

[0021] placing the first quartz single crystal wafer at a first target azimuth angle and the second quartz single crystal wafer at a second target azimuth angle, wherein the second target azimuth angle is rotated 60°, 180°, or 300° relative to the first target azimuth angle; and bonding the first quartz single crystal wafer and the second quartz single crystal wafer together using acetone liquid;

[0022] Among them, when the quartz single crystal chip with a crystal plane index of (0001) is at a target azimuth angle, after the femtosecond laser generated by the laser source is vertically incident on the surface of the quartz single crystal chip, the terahertz wave amplitude generated by the quartz single crystal chip is the largest, and the target azimuth angle has a period of 120° within 360° in the plane, and the target azimuth angle includes the first target azimuth angle and the second target azimuth angle.

[0023] Optionally, the method for preparing the terahertz wave transmitter further includes:

[0024] The first quartz single crystal wafer is double-sided polished in advance, and the second quartz single crystal wafer is double-sided polished in advance.

[0025] Compared with the existing technology, the above technical solution has the following advantages:

[0026] The terahertz wave emitter provided in an embodiment of the present application includes a laser source and a first quartz single crystal wafer and a second quartz single crystal wafer bonded together. The laser source is used to generate a femtosecond laser with a polarization direction. The crystal plane index of the first quartz single crystal wafer and the second quartz single crystal wafer are both (0001). When a femtosecond laser with a polarization direction is vertically incident on the surface of a quartz single crystal with a crystal plane index of (0001), a time-varying polarization electric field is excited in the quartz single crystal, thereby generating a polarization current, which in turn generates a terahertz wave. Moreover, terahertz signals with opposite polarities are generated near the incident surface and the exit surface of the quartz single crystal, respectively, one with a positive polarity terahertz wave peak and the other with a negative polarity terahertz wave peak. For the incident surface or the exit surface of the quartz single crystal, the amplitude of the terahertz wave generated by the quartz single crystal is related to the azimuth angle of the quartz single crystal. When the quartz single crystal is rotated to the target azimuth angle, the amplitude of the terahertz wave generated by the quartz single crystal is the largest, that is, the terahertz wave peak is generated. At the same time, considering that the quartz single crystal The target azimuth angle is 120° in a 360° plane, and the amplitude of the terahertz wave generated by the quartz single crystal is proportional to cos(3φ), where φ is the angle of rotation of the current azimuth angle of the quartz single crystal relative to the 0° azimuth angle, and the 0° azimuth angle is a target azimuth angle of the marked quartz single crystal. It can be seen that when the quartz single crystal is rotated to 120° or 240° relative to the 0° azimuth angle, the amplitude of the terahertz wave generated by the quartz single crystal is the largest, and the polarity is the same as when the quartz single crystal is at the 0° azimuth angle; when the quartz single crystal is rotated to 60°, 180°, or 300° relative to the 0° azimuth angle, the amplitude of the terahertz wave generated by the quartz single crystal is the largest, but the polarity is opposite to that when the quartz single crystal is at the 0° azimuth angle.

[0027] Therefore, in the terahertz wave emitter provided in the embodiment of the present application, the first quartz single crystal is set at a first target azimuth angle, so that after the femtosecond laser generated by the laser source is vertically incident on the surface of the first quartz single crystal, the amplitude of the terahertz wave generated by the first quartz single crystal is the largest; at the same time, the second quartz single crystal is set at a second target azimuth angle, so that after the femtosecond laser generated by the laser source is vertically incident on the surface of the second quartz single crystal, the amplitude of the terahertz wave generated by the second quartz single crystal is also the largest; that is, the target azimuth angles of the quartz single crystal include the first target azimuth angle and the second target azimuth angle; and the second target azimuth angle is rotated by 60°, 180° or 300° relative to the first target azimuth angle, that is, with the first target azimuth angle as 0° azimuth, the second target azimuth angle is 60°, 180° or 300°, then When a femtosecond laser with a polarization direction is excited, when the incident surface of the first quartz single crystal wafer generates a terahertz wave peak of one polarity, the exit surface of the first quartz single crystal wafer generates a terahertz wave peak of the opposite polarity, and the incident surface of the second quartz single crystal wafer also generates a terahertz wave peak of the opposite polarity. That is, the exit surface of the first quartz single crystal wafer and the incident surface of the second quartz single crystal wafer generate terahertz wave peaks of the same polarity, and the exit surface of the first quartz single crystal wafer and the incident surface of the second quartz single crystal wafer are tightly bonded together. In this way, the terahertz wave peaks of the same polarity generated by the first quartz single crystal wafer and the second quartz single crystal wafer have the same phase, so that the terahertz wave peaks of the same polarity generated by the first quartz single crystal wafer and the second quartz single crystal wafer are superimposed, thereby extending the effective phase matching length, so that the intensity of the ultimately generated terahertz wave is significantly improved.

[0028] In addition, the terahertz wave emitter provided in the embodiment of the present application only requires a laser source and two quartz single crystals, which are then glued together at a certain azimuth angle. The preparation method is simple, and the structure of the prepared terahertz wave emitter is also simple. Moreover, since the cost of quartz single crystals is relatively low, the terahertz wave emitter provided in the embodiment of the present application has a low production cost and can meet more commercial needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 A schematic structural diagram of a terahertz wave transmitter provided in an embodiment of the present application;

[0031] Figure 2This is a schematic diagram of the change in the intensity of the terahertz wave generated by a terahertz wave transmitter provided in an embodiment of the present application over time, and a schematic diagram of the change in the intensity of the terahertz wave generated by an existing terahertz wave transmitter including a quartz single crystal wafer over time.

[0032] Reference numerals:

[0033] 100 - laser source; 210 - first quartz single crystal wafer; 220 - second quartz single crystal wafer. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0036] As described in the background technology section, how to overcome the phase matching problem of nonlinear crystals in terahertz wave transmitters to improve the intensity of terahertz waves is a technical problem that needs to be solved urgently by those skilled in the art.

[0037] In view of this, an embodiment of the present application provides a terahertz wave transmitter. Figure 1 FIG. 1 shows a schematic structural diagram of a terahertz wave transmitter provided in an embodiment of the present application. Figure 1 As shown, the terahertz wave transmitter includes:

[0038] The laser source 100 is used to generate femtosecond laser light, and the femtosecond laser light has a polarization direction;

[0039] A first quartz single crystal wafer 210 and a second quartz single crystal wafer 220 , wherein the crystal plane index of the first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 are both (0001), and the first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 are pasted together;

[0040] The first quartz single crystal wafer 210 is at a first target azimuth angle, and the second quartz single crystal wafer 220 is at a second target azimuth angle, which is rotated 60°, 180°, or 300° relative to the first target azimuth angle. When the quartz single crystal wafer with a crystal plane index of (0001) is at the target azimuth angle, after the femtosecond laser generated by the laser source is vertically incident on the surface of the quartz single crystal wafer, the terahertz wave amplitude generated by the quartz single crystal wafer is the largest. The target azimuth angle of the quartz single crystal wafer is 120° in period within 360° within the plane, and the target azimuth angle of the quartz single crystal wafer includes the first target azimuth angle and the second target azimuth angle.

[0041] It is understandable that the femtosecond laser generated by the laser source 100 has a polarization direction, that is, the femtosecond laser generated by the laser source 100 is linearly polarized light, that is, the electric field of the femtosecond laser beam oscillates in a specific direction perpendicular to the propagation direction of the laser beam.

[0042] It should be noted that when a polarized femtosecond laser is incident perpendicularly on the surface of a quartz crystal with a crystal index of (0001), it excites a time-varying polarization electric field within the crystal, generating a polarization current, which in turn generates terahertz waves. For a quartz crystal of a certain thickness, a terahertz signal is generated within the thickness range near the incident surface of the crystal, and a terahertz signal is also generated within the thickness range near the exit surface of the crystal. The thicknesses contributing to terahertz generation near the incident surface (i.e., the surface first hit by the femtosecond laser) and the exit surface (the surface opposite the incident surface) of the quartz crystal are comparable. The two terahertz signals generated near the incident and exit surfaces of the quartz crystal, respectively, have opposite polarities: one with a positive terahertz wave peak and the other with a negative terahertz wave peak. When the thickness of a quartz crystal crystal falls below a certain range, the terahertz signal generated near the crystal's incident surface and the terahertz signal generated near its exit surface combine into a single terahertz signal, in which terahertz wave peaks of opposite polarity alternate. The terahertz signal generated near the exit surface of the quartz crystal crystal is associated with an additional phase due to phase mismatch, while the terahertz signal generated near the crystal's incident surface is solely related to the material itself.

[0043] It should also be noted that for the incident surface or the exit surface of the quartz single crystal, the amplitude of the terahertz wave generated by the quartz single crystal is related to the azimuth angle of the quartz single crystal. When the quartz single crystal is rotated to the target azimuth angle, the amplitude of the terahertz wave generated by the quartz single crystal is the largest, that is, the terahertz wave peak is generated. In addition, the polarities of the two terahertz signals generated near the incident surface and the exit surface of the quartz single crystal are opposite, one has a positive polarity terahertz wave peak, and the other has a negative polarity terahertz wave peak.

[0044] The target azimuth angle of a quartz single crystal wafer with a crystal plane index of (0001) is 120° in period within 360° within the plane. Specifically, by rotating the quartz single crystal wafer with a crystal plane index of (0001) until the quartz single crystal wafer can generate a terahertz wave with the maximum amplitude (i.e., the terahertz wave peak), the quartz single crystal wafer is at a target azimuth angle, and the target azimuth angle of the quartz single crystal wafer at this time is marked as the 0° azimuth angle. Then, when the quartz single crystal wafer is at an azimuth angle of 120° or 240°, the amplitude of the terahertz wave generated by the quartz single crystal wafer is the same as the amplitude of the terahertz wave generated when the quartz single crystal wafer is at the 0° azimuth angle, both being the maximum. The polarity of the terahertz wave generated by the quartz single crystal wafer is also the same as the polarity of the terahertz wave generated when the quartz single crystal wafer is at the 0° azimuth angle.

[0045] Moreover, based on a target azimuth angle of a quartz single crystal wafer marked with a crystal plane index of (0001) being an azimuth angle of 0°, the amplitude of the terahertz wave generated by the quartz single crystal wafer with a crystal plane index of (0001) is proportional to cos(3φ), where φ is the angle of rotation of the current azimuth angle of the quartz single crystal wafer relative to the azimuth angle of 0°. For example, when φ=0°, the quartz single crystal wafer is at a target azimuth angle, and the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest; when φ=60°, the quartz single crystal wafer is at another target azimuth angle, and the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, but the polarity is opposite to that when φ=0°; when φ=120°, the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, and the polarity is the same as that when φ=0°; when φ=180°, the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, but the polarity is opposite to that when φ=0°; when φ=240°, the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, and the polarity is the same as that when φ=0°; when φ=300°, the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, but the polarity is opposite to that when φ=0°.

[0046] In summary, when the quartz single crystal wafer is rotated to 120° or 240° relative to the 0° azimuth angle, the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, and the polarity is the same as when the quartz single crystal wafer is at the 0° azimuth angle; when the quartz single crystal wafer is rotated to 60°, 180° or 300° relative to the 0° azimuth angle, the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, but the polarity is opposite to when the quartz single crystal wafer is at the 0° azimuth angle.

[0047] Through the above analysis, it can be understood that in the terahertz wave emitter provided in the embodiment of the present application, the first quartz single crystal 210 is set at a first target azimuth angle, so that after the femtosecond laser generated by the laser source 100 is vertically incident on the surface of the first quartz single crystal 210, the amplitude of the terahertz wave generated by the first quartz single crystal 210 is the largest; at the same time, the second quartz single crystal 220 is set at a second target azimuth angle, so that after the femtosecond laser generated by the laser source 100 is vertically incident on the surface of the second quartz single crystal 220, the amplitude of the terahertz wave generated by the second quartz single crystal 220 is also the largest; that is, the target azimuth angles of the quartz single crystal include the first target azimuth angle and the second target azimuth angle; and the second target azimuth angle is rotated by 60°, 180° or 300° relative to the first target azimuth angle, that is, with the first target azimuth angle as 0° azimuth, the second target azimuth angle is 60°, 180° or 300°, then Therefore, under the excitation of a femtosecond laser with a polarization direction, the incident surface of the first quartz single crystal 210 generates a terahertz wave peak of one polarity, the exit surface of the first quartz single crystal 210 generates a terahertz wave peak of the opposite polarity, and the incident surface of the second quartz single crystal 220 also generates a terahertz wave peak of the opposite polarity. That is, the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220 generate terahertz wave peaks of the same polarity, and the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220 are tightly bonded together. In this way, the terahertz wave peaks of the same polarity generated by the first quartz single crystal 210 and the second quartz single crystal 220 have the same phase, so that the terahertz wave peaks of the same polarity generated by the first quartz single crystal 210 and the second quartz single crystal 220 are superimposed, thereby extending the effective phase matching length, so that the intensity of the ultimately generated terahertz wave is significantly improved.

[0048] In addition, the terahertz wave emitter provided in the embodiment of the present application only requires a laser source and two quartz single crystals, which are then glued together at a certain azimuth angle. The preparation method is simple, and the structure of the prepared terahertz wave emitter is also simple. Moreover, since the cost of quartz single crystals is relatively low, the terahertz wave emitter provided in the embodiment of the present application has a low production cost and can meet more commercial needs.

[0049] To verify the above analysis, Figure 2 A schematic diagram showing the change in the intensity of a terahertz wave generated by a terahertz wave transmitter provided in an embodiment of the present application over time is shown, wherein the second target azimuth angle of the second quartz single crystal wafer is rotated 60° relative to the first target azimuth angle of the first quartz single crystal wafer. For comparison, Figure 2A schematic diagram of the change in the intensity of the terahertz wave generated by the existing terahertz wave emitter including a quartz single crystal piece over time is also shown. It can be seen that compared with the existing terahertz wave emitter including a quartz single crystal piece, the intensity of the terahertz wave generated by the terahertz wave emitter provided in the embodiment of the present application is significantly improved.

[0050] Optionally, the thickness of the first quartz single crystal 210 is less than 0.3 mm, and the thickness of the second quartz single crystal 220 is less than 0.3 mm. This is because, if the thickness of the quartz single crystal is relatively large, after the polarized femtosecond laser is incident on the surface of the quartz single crystal, two time-resolved terahertz signals will be generated near the incident surface and near the exit surface of the quartz single crystal, respectively, and the two time-resolved terahertz signals have opposite polarities. However, when the thickness of the quartz single crystal is relatively small, less than 0.3 mm, the two terahertz signals generated by the quartz single crystal are no longer time-resolved, but are combined into one terahertz signal, thereby facilitating the superposition of terahertz wave peaks of the same polarity generated by the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220, thereby increasing the intensity of the ultimately generated terahertz wave.

[0051] Further optionally, the thickness of the first quartz single crystal wafer 210 is equal to the thickness of the second quartz single crystal wafer 220 .

[0052] Optionally, the shape of the first quartz single crystal 210 is the same as the shape of the second quartz single crystal 220. It is understood that when the shape of the first quartz single crystal 210 is the same as the shape of the second quartz single crystal 220, after setting the first quartz single crystal 210 to the first target azimuth angle, it is only necessary to compare the first quartz single crystal 210 and rotate the second quartz single crystal 220 relative to the first quartz single crystal 210 by 60°, 180°, or 300° to set the second quartz single crystal 220 to the second target azimuth angle, making the design and preparation more convenient.

[0053] Optionally, the first quartz single crystal 210 and the second quartz single crystal 220 are bonded together using acetone (a highly volatile liquid). Specifically, the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220 are bonded together using the acetone liquid. Under the action of the acetone liquid, the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220 are bonded very tightly together, ensuring that there is no gap between the two surfaces. This facilitates the superposition of terahertz wave peaks of the same polarity generated by the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220, thereby increasing the intensity of the resulting terahertz wave.

[0054] Alternatively, the first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 may be tightly adhered together by other highly volatile liquids to ensure that there is no gap between the two surfaces.

[0055] Optionally, the surface of the first quartz single crystal 210 facing away from the second quartz single crystal 220 and the surface facing the second quartz single crystal 220 are both polished surfaces. Similarly, the surface of the second quartz single crystal 220 facing away from the first quartz single crystal 210 and the surface facing the first quartz single crystal 210 are also polished surfaces.

[0056] Optionally, both the first quartz single crystal 210 and the second quartz single crystal 220 are α-quartz single crystals. α-quartz (low-temperature quartz) is a common and important variant of quartz. α-quartz single crystals are colorless and transparent, have a glassy luster, high hardness, moderate specific gravity, and excellent piezoelectric and optical properties. These properties make α-quartz single crystals widely used in various fields such as electronics, optics, chemistry, and precision instruments, all at a low cost.

[0057] Based on the same inventive concept, the present invention also provides a method for preparing a terahertz wave transmitter, referring to Figure 1 As shown, the preparation method of the terahertz wave transmitter includes:

[0058] S100: providing a laser source 100, wherein the laser source 100 is used to generate femtosecond laser light, and the femtosecond laser light has a polarization direction.

[0059] S200 : providing a first quartz single crystal wafer 210 and a second quartz single crystal wafer 220 , wherein the crystal plane index of the first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 are both (0001).

[0060] S300: The first quartz single crystal wafer 210 is placed at a first target azimuth angle, and the second quartz single crystal wafer 220 is placed at a second target azimuth angle, wherein the second target azimuth angle is rotated 60°, 180°, or 300° relative to the first target azimuth angle; and the first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 are bonded together using acetone liquid.

[0061] Among them, when the quartz single crystal wafer with a crystal plane index of (0001) is at a target azimuth angle, after the femtosecond laser generated by the laser source 100 is vertically incident on the surface of the quartz single crystal wafer, the terahertz wave amplitude generated by the quartz single crystal wafer is the largest. The target azimuth angle of the quartz single crystal wafer is 120° in period within 360° in the plane, and the target azimuth angle of the quartz single crystal wafer includes a first target azimuth angle and a second target azimuth angle.

[0062] Optionally, the method for preparing the terahertz wave transmitter provided in the embodiment of the present application may further include:

[0063] S400: Preliminarily perform double-side polishing on the first quartz single crystal wafer 210 and preliminarily perform double-side polishing on the second quartz single crystal wafer 220.

[0064] Specifically, acetone liquid can be dripped onto one surface of the double-sided polished first quartz single crystal wafer 210 or the second quartz single crystal wafer 220. Before the acetone liquid evaporates, the first quartz single crystal wafer 210 is placed at a first target azimuth angle, and the second quartz single crystal wafer 220 is placed at a second target azimuth angle, with the second target azimuth angle rotated 60°, 180°, or 300° relative to the first target azimuth angle. The first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 are then bonded together to ensure that there is no gap.

[0065] In this way, after the femtosecond laser generated by the laser source 100 is vertically incident on the surface of the first quartz single crystal 210, the amplitude of the terahertz wave generated by the first quartz single crystal 210 is the largest; and after the femtosecond laser generated by the laser source 100 is vertically incident on the surface of the second quartz single crystal 220, the amplitude of the terahertz wave generated by the second quartz single crystal 220 is also the largest; under the excitation of the femtosecond laser with a polarization direction, the incident surface of the first quartz single crystal 210 generates a terahertz wave peak of one polarity, the exit surface of the first quartz single crystal 210 generates a terahertz wave peak of the opposite polarity, and the incident surface of the second quartz single crystal 220 also generates a terahertz wave peak of the opposite polarity. The terahertz wave peaks of opposite polarities are generated, that is, the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220 generate terahertz wave peaks with the same polarity, and the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220 are tightly bonded together. Therefore, the terahertz wave peaks with the same polarity generated by the first quartz single crystal 210 and the second quartz single crystal 220 have the same phase, so that the terahertz wave peaks with the same polarity generated by the first quartz single crystal 210 and the second quartz single crystal 220 are superimposed, thereby extending the effective phase matching length, so that the intensity of the terahertz wave finally generated is significantly improved.

[0066] In addition, the preparation method of the terahertz wave emitter provided in the embodiment of the present application only requires providing a laser source and two quartz single crystals, and then pasting the two quartz single crystals together at a certain azimuth angle. The preparation method is simple, and the structure of the prepared terahertz wave emitter is also simple. Moreover, since the cost of quartz single crystals is relatively low, the production cost is low, which can meet more commercial needs.

[0067] Optionally, the thickness of the first quartz single crystal 210 is less than 0.3 mm, and the thickness of the second quartz single crystal 220 is less than 0.3 mm. This is because, if the thickness of the quartz single crystal is relatively large, after the polarized femtosecond laser is incident on the surface of the quartz single crystal, two time-resolved terahertz signals will be generated near the incident surface and near the exit surface of the quartz single crystal, respectively, and the two time-resolved terahertz signals have opposite polarities. However, when the thickness of the quartz single crystal is relatively small, less than 0.3 mm, the two terahertz signals generated by the quartz single crystal are no longer time-resolved, but are combined into one terahertz signal, thereby facilitating the superposition of terahertz wave peaks of the same polarity generated by the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220, thereby increasing the intensity of the ultimately generated terahertz wave.

[0068] Further optionally, the thickness of the first quartz single crystal wafer 210 is equal to the thickness of the second quartz single crystal wafer 220 .

[0069] Optionally, the shape of the first quartz single crystal 210 is the same as the shape of the second quartz single crystal 220. It is understood that when the shape of the first quartz single crystal 210 is the same as the shape of the second quartz single crystal 220, after setting the first quartz single crystal 210 to the first target azimuth angle, it is only necessary to compare the first quartz single crystal 210 and rotate the second quartz single crystal 220 relative to the first quartz single crystal 210 by 60°, 180°, or 300° to set the second quartz single crystal 220 to the second target azimuth angle, making the design and preparation more convenient.

[0070] Optionally, both the first quartz single crystal 210 and the second quartz single crystal 220 are α-quartz single crystals. α-quartz (low-temperature quartz) is a common and important variant of quartz. α-quartz single crystals are colorless and transparent, have a glassy luster, high hardness, moderate specific gravity, and excellent piezoelectric and optical properties. These properties make α-quartz single crystals widely used in various fields such as electronics, optics, chemistry, and precision instruments, all at a low cost.

[0071] The various parts in this manual are described in a combination of parallel and progressive manners. Each part focuses on the differences from other parts, and the same or similar parts between the various parts can be referenced to each other.

[0072] With respect to the above description of the disclosed embodiments, the features described in the various embodiments in this specification may be interchanged or combined with one another to enable those skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A terahertz wave transmitter, characterized in that: include: A laser source, configured to generate a femtosecond laser, wherein the femtosecond laser has a polarization direction; A first quartz single crystal wafer and a second quartz single crystal wafer, wherein the crystal plane index of the first quartz single crystal wafer and the second quartz single crystal wafer are both (0001), and the first quartz single crystal wafer and the second quartz single crystal wafer are bonded together; The first quartz single crystal wafer is at a first target azimuth angle, and the second quartz single crystal wafer is at a second target azimuth angle, and the second target azimuth angle is rotated 60°, 180°, or 300° relative to the first target azimuth angle; when the quartz single crystal wafer with a crystal plane index of (0001) is at the target azimuth angle, after the femtosecond laser generated by the laser source is vertically incident on the surface of the quartz single crystal wafer, the terahertz wave amplitude generated by the quartz single crystal wafer is the largest, and the target azimuth angle has a period of 120° within 360° in the plane, and the target azimuth angle includes the first target azimuth angle and the second target azimuth angle.

2. The terahertz wave transmitter according to claim 1, characterized in that: The thickness of the first quartz single crystal sheet is less than 0.3 mm, and the thickness of the second quartz single crystal sheet is less than 0.3 mm.

3. The terahertz wave transmitter according to claim 2, characterized in that: The thickness of the first quartz single crystal sheet is equal to the thickness of the second quartz single crystal sheet.

4. The terahertz wave transmitter according to claim 1, characterized in that: The shape of the first quartz single crystal sheet is the same as the shape of the second quartz single crystal sheet.

5. The terahertz wave transmitter according to claim 1, characterized in that: The first quartz single crystal sheet and the second quartz single crystal sheet are bonded together by acetone liquid.

6. The terahertz wave transmitter according to claim 1, characterized in that: The surface of the first quartz single crystal wafer facing away from the second quartz single crystal wafer and the surface of the first quartz single crystal wafer facing the second quartz single crystal wafer are both polished surfaces; The surface of the second quartz single crystal wafer facing away from the first quartz single crystal wafer and the surface of the second quartz single crystal wafer facing the first quartz single crystal wafer are both polished surfaces.

7. The terahertz wave transmitter according to any one of claims 1 to 6, characterized in that: The first quartz single crystal sheet and the second quartz single crystal sheet are both α-quartz single crystal sheets.

8. A method for preparing a terahertz wave transmitter, characterized in that: include: Providing a laser source, wherein the laser source is used to generate femtosecond laser light, wherein the femtosecond laser light has a polarization direction; Providing a first quartz single crystal wafer and a second quartz single crystal wafer, wherein the crystal plane index of the first quartz single crystal wafer and the second quartz single crystal wafer are both (0001); placing the first quartz single crystal wafer at a first target azimuth angle and the second quartz single crystal wafer at a second target azimuth angle, wherein the second target azimuth angle is rotated 60°, 180°, or 300° relative to the first target azimuth angle; and bonding the first quartz single crystal wafer and the second quartz single crystal wafer together using acetone liquid; Among them, when the quartz single crystal chip with a crystal plane index of (0001) is at a target azimuth angle, after the femtosecond laser generated by the laser source is vertically incident on the surface of the quartz single crystal chip, the terahertz wave amplitude generated by the quartz single crystal chip is the largest, and the target azimuth angle has a period of 120° within 360° in the plane, and the target azimuth angle includes the first target azimuth angle and the second target azimuth angle.

9. The method for preparing a terahertz wave transmitter according to claim 8, characterized in that: The method for preparing the terahertz wave transmitter further includes: The first quartz single crystal wafer is double-sided polished in advance, and the second quartz single crystal wafer is double-sided polished in advance.

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