Terahertz wave emitter and preparation method thereof

Abstract

The invention discloses a terahertz wave emitter and a preparation method thereof, and relates to the technical field of terahertz photoelectric devices.The terahertz wave emitter comprises a laser source, a first quartz single crystal wafer and a second quartz single crystal wafer, the crystal face indexes of the first quartz single crystal wafer and the second quartz single crystal wafer are (0001), and the first quartz single crystal wafer and the second quartz single crystal wafer are pasted together. The first quartz single crystal wafer is located at a first target azimuth angle, the second quartz single crystal wafer is located at a second target azimuth angle, and the second target azimuth angle rotates by 60 degrees or 180 degrees or 300 degrees relative to the first target azimuth angle, so that under excitation of femtosecond laser with a polarization direction, terahertz wave peak values with the same polarity generated by the first quartz single crystal wafer and the second quartz single crystal wafer are the same in phase; according to the terahertz wave emitter, the terahertz wave peak values with the same polarity generated by the first quartz single crystal wafer and the second quartz single crystal wafer are superposed, the effective phase matching length is prolonged, the intensity of the finally generated terahertz wave is remarkably improved, and the emitter is simple in structure, simple in preparation method and low in 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 a frequency of 0.1 THz to 10 THz. The frequency range covered by terahertz waves is also called the "Terahertz gap". Due to its special band, terahertz waves have many excellent properties, such as penetration, safety, and fingerprint properties, and are of great significance in the research of materials science and material science. Since the terahertz wave band is between microwaves and infrared waves, it is difficult to generate and detect using traditional electronics and photonics. Therefore, people have done little research on electromagnetic waves in this band in the past many years. In recent years, with the advancement of ultrafast laser technology and high-precision circuit technology, terahertz technology has ushered in rapid development.

[0003] Generation and detection are key links in terahertz technology, so terahertz wave transmitters are key devices in terahertz systems. Existing photonic methods for generating terahertz waves include photoconductivity and optical rectification. Among them, the photoconductivity method uses the photoelectric effect to irradiate light radiation onto semiconductor materials to excite carriers therein. The carriers accelerate and move under the drive of the bias electric field to generate terahertz radiation. Photoconductive antennas are important devices that use photoconductive method to generate terahertz waves; however, in photoconductive antenna technology, the inherent phonon absorption of the material limits the intensity and bandwidth of the generated terahertz waves, and the cost of photoconductive antennas is expensive. The optical rectification method uses ultrashort laser pulses to be incident on nonlinear crystals, and uses the nonlinear effect of nonlinear crystals to generate terahertz pulse waves; however, in the optical rectification method, the phase matching between the excitation light and the generated terahertz light in the nonlinear crystal will seriously affect the bandwidth and intensity of the generated terahertz waves.

[0004] Existing electronic methods for generating terahertz waves include new terahertz wave transmitters based on spin electronics, which use femtosecond laser pulses to excite spin electrons in materials and generate terahertz waves through the interaction and propagation of spin electrons. Compared with new terahertz wave transmitters based on spin electronics, the optical rectification method uses the nonlinear effect of nonlinear crystals to generate terahertz waves, which is simpler and has a higher intensity. However, 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. Summary of the invention

[0005] In order to solve the above technical problems, the embodiment of the present application provides a terahertz wave transmitter and a preparation method thereof, by stacking and pasting two quartz single crystal sheets together and controlling the azimuth angles of the two quartz single crystal sheets, so that the peaks of terahertz waves with the same polarity generated by femtosecond lasers passing through the two quartz single crystal sheets are in phase, the effective phase matching length is extended, and the intensity of the generated terahertz wave is significantly improved.

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

[0007] A terahertz wave transmitter, comprising:

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

[0009] A first quartz single crystal sheet and a second quartz single crystal sheet, wherein the crystal plane indexes of the first quartz single crystal sheet and the second quartz single crystal sheet are both (0001), and the first quartz single crystal sheet and the second quartz single crystal sheet are pasted 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 a 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 amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, and the target azimuth angle is 120° as a period 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 sheet and the second quartz single crystal sheet are bonded together by 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 sheet and the second quartz single crystal sheet are both α-quartz single crystal sheets.

[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 sheet and a second quartz single crystal sheet, wherein the crystal plane indexes of the first quartz single crystal sheet and the second quartz single crystal sheet are both (0001);

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

[0022] Among them, when a 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 amplitude of the terahertz wave 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 prior art, the above technical solution has the following advantages:

[0026] The terahertz wave transmitter provided in the embodiment of the present application includes a laser source and a first quartz single crystal sheet and a second quartz single crystal sheet pasted 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 sheet and the second quartz single crystal sheet are both (0001). When a femtosecond laser with a polarization direction is vertically incident on the surface of a quartz single crystal wafer with a crystal plane index of (0001), a polarization electric field that varies with time is excited in the quartz single crystal wafer, 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 near the exit surface of the quartz single crystal wafer, respectively, one with a positive terahertz wave peak and the other with a negative terahertz wave peak. For the incident surface or the exit surface of the quartz single crystal wafer, the amplitude of the terahertz wave generated by the quartz single crystal wafer is related to the azimuth angle of the quartz single crystal wafer. When the quartz single crystal wafer is rotated to the target azimuth angle, the amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, that is, the terahertz wave peak is generated. At the same time, considering that the quartz single crystal wafer The target azimuth angle is 120° as a period within 360° in the plane, and the amplitude of the terahertz wave generated by the quartz single crystal is proportional to cos(3φ), wherein 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; thus, it can be seen that when the quartz single crystal is rotated to an azimuth angle of 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 when the quartz single crystal is at the 0° azimuth angle.

[0027] Therefore, in the terahertz wave transmitter 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 angle of the quartz single crystal includes 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, taking the first target azimuth angle as 0° azimuth angle, the second target azimuth angle is 60°, 180° or 300°, then When the incident surface of the first quartz single crystal wafer generates a terahertz wave peak with one polarity under the excitation of a femtosecond laser with a polarization direction, the exit surface of the first quartz single crystal wafer generates a terahertz wave peak with the opposite polarity, and the incident surface of the second quartz single crystal wafer also generates a terahertz wave peak with 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 with 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 attached together, so that the terahertz wave peaks with 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 with 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 terahertz wave finally generated is significantly improved.

[0028] In addition, the terahertz wave emitter provided in the embodiment of the present application only needs to provide a laser source and two quartz single crystal sheets, and the two quartz single crystal sheets are pasted 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 crystal sheets 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative work.

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

[0031] Figure 2A schematic diagram of the variation of the intensity of a terahertz wave generated by a terahertz wave transmitter provided in an embodiment of the present application over time, and a schematic diagram of the variation of the intensity of a 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 the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work 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, but the present application may also be implemented in other ways different from those described herein, and 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 A schematic diagram of the structure of a terahertz wave transmitter provided in an embodiment of the present application is shown. 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, the crystal plane indexes 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, 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 a 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 amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest. The target azimuth angle of the quartz single crystal wafer is 120° as a period within 360° in 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 femtosecond laser with a polarization direction is incident vertically on the surface of a quartz single crystal with a crystal plane index of (0001), a polarization electric field that varies with time will be excited in the quartz single crystal, thereby generating a polarization current, which in turn generates a terahertz wave. For a quartz single crystal of a certain thickness, a terahertz signal will be generated within the thickness range near the incident surface of the quartz single crystal, and a terahertz signal will also be generated within the thickness range near the exit surface of the quartz single crystal. The thickness of the incident surface (i.e., the surface first incident by the femtosecond laser) and the exit surface (the surface opposite to the incident surface) of the quartz single crystal that contributes to the generation of terahertz is equivalent. 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 terahertz wave peak, and the other has a negative terahertz wave peak. When the thickness of the quartz single crystal is less than a certain range, the terahertz signal generated near the incident surface of the quartz single crystal and the terahertz signal generated near its exit surface are combined into a terahertz signal, in which terahertz wave peaks with opposite polarities are generated alternately. The terahertz signal generated near the exit surface of the quartz single crystal is related to the additional phase obtained due to phase mismatch, while the terahertz signal generated near the incident surface of the quartz single crystal is only 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, and 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 terahertz wave peak, and the other has a negative terahertz wave peak.

[0044] The target azimuth angle of the quartz single crystal wafer with a crystal plane index of (0001) is 120° as a period within 360° in the plane. Specifically, by rotating the quartz single crystal wafer with a crystal plane index of (0001) to the point where the quartz single crystal wafer can generate a terahertz wave with the maximum amplitude (i.e., a 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 a 0° azimuth angle. 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 by the quartz single crystal wafer when the quartz single crystal wafer is at a 0° azimuth angle, and both are 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 by the quartz single crystal wafer when the quartz single crystal wafer is at a 0° azimuth angle.

[0045] Moreover, based on a target azimuth angle of a quartz single crystal wafer with a marked 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), wherein φ is the angle at which the current azimuth angle of the quartz single crystal wafer is rotated relative to the azimuth angle of 0°. For example, when φ=0°, the quartz single crystal piece is at a target azimuth angle, and the amplitude of the terahertz wave generated by the quartz single crystal piece is the largest; when φ=60°, the quartz single crystal piece is at another target azimuth angle, and the amplitude of the terahertz wave generated by the quartz single crystal piece 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 piece 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 piece 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 piece 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 piece 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 azimuth angle of 0°, 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 an azimuth angle of 0°; when the quartz single crystal wafer is rotated to 60°, 180° or 300° relative to the azimuth angle of 0°, 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 an azimuth angle of 0°.

[0047] Through the above analysis, it can be understood that in the terahertz wave transmitter 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 angle of the quartz single crystal includes 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 angle, the second target azimuth angle is 60°, 180° or 300°, then Then, 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 with one polarity, the exit surface of the first quartz single crystal 210 generates a terahertz wave peak with the opposite polarity, and the incident surface of the second quartz single crystal 220 also generates a terahertz wave peak with 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 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 adhered together, 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 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.

[0048] In addition, the terahertz wave emitter provided in the embodiment of the present application only needs to provide a laser source and two quartz single crystal sheets, and the two quartz single crystal sheets are pasted 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 crystal sheets 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 The schematic diagram of the change of the intensity of the terahertz wave generated by the terahertz wave transmitter provided in the embodiment of the present application over time is shown, wherein the second target azimuth angle of the second quartz single crystal wafer is rotated by 60° relative to the first target azimuth angle of the first quartz single crystal wafer, for comparison, Figure 2A schematic diagram showing the variation of the intensity of the terahertz wave generated by the existing terahertz wave transmitter including a quartz single crystal sheet over time is also shown. It can be seen that compared with the existing terahertz wave transmitter including a quartz single crystal sheet, the intensity of the terahertz wave generated by the terahertz wave transmitter 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 femtosecond laser with a polarization direction 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; and 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, which is conducive to the superposition of the terahertz wave peaks with 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 terahertz wave finally generated.

[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 understandable 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 be at 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 be at the second target azimuth angle, making the design and preparation easier.

[0053] Optionally, the first quartz single crystal 210 and the second quartz single crystal 220 are pasted together by acetone liquid (strong volatile liquid). That is, the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220 are pasted together by acetone liquid. Under the action of acetone liquid, the exit surface of the first quartz single crystal 210 and the incident surface of the second quartz single crystal 220 are pasted together very tightly, ensuring that there is no gap between the two surfaces, which is conducive to the superposition of the terahertz wave peaks with 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 improving the intensity of the terahertz wave finally generated.

[0054] Alternatively, the first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 may also 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 wafer 210 facing away from the second quartz single crystal wafer 220 and the surface facing the second quartz single crystal wafer 220 are both polished surfaces. Similarly, the surface of the second quartz single crystal wafer 220 facing away from the first quartz single crystal wafer 210 and the surface facing the first quartz single crystal wafer 210 are also polished surfaces.

[0056] Optionally, the first quartz single crystal 210 and the second quartz single crystal 220 are both α-quartz single crystals. α-quartz (low temperature quartz) is a common and important variant of quartz. α-quartz single crystal is colorless and transparent, has glass luster, high hardness, moderate specific gravity, and has good piezoelectricity and optical properties. These characteristics make α-quartz single crystal widely used in many fields such as electronics, optics, chemistry, precision instruments, etc., and the cost is low.

[0057] Based on the same inventive concept, the present application 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 indexes of the first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 are both (0001).

[0060] S300: placing the first quartz single crystal wafer 210 at a first target azimuth angle, placing the second quartz single crystal wafer 220 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 pasting the first quartz single crystal wafer 210 and the second quartz single crystal wafer 220 together by using acetone liquid;

[0061] 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 100 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 of the quartz single crystal chip is 120° as a period within 360° in the plane, and the target azimuth angle of the quartz single crystal chip 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, and the second target azimuth angle is 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 pasted together to ensure that there is no gap.

[0065] Thus, 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 with opposite polarities are superimposed, that is, the exit surface of the first quartz single crystal piece 210 and the incident surface of the second quartz single crystal piece 220 generate terahertz wave peaks with the same polarity, and the exit surface of the first quartz single crystal piece 210 and the incident surface of the second quartz single crystal piece 220 are tightly adhered together. Therefore, the terahertz wave peaks with the same polarity generated by the first quartz single crystal piece 210 and the second quartz single crystal piece 220 have the same phase, so that the terahertz wave peaks with the same polarity generated by the first quartz single crystal piece 210 and the second quartz single crystal piece 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 crystal sheets, and pasting the two quartz single crystal sheets 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 crystal sheets 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 femtosecond laser with a polarization direction 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; and 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, which is conducive to the superposition of the terahertz wave peaks with 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 terahertz wave finally generated.

[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 understandable 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 be at 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 be at the second target azimuth angle, making the design and preparation easier.

[0070] Optionally, the first quartz single crystal 210 and the second quartz single crystal 220 are both α-quartz single crystals. α-quartz (low temperature quartz) is a common and important variant of quartz. α-quartz single crystal is colorless and transparent, has glass luster, high hardness, moderate specific gravity, and has good piezoelectricity and optical properties. These characteristics make α-quartz single crystal widely used in many fields such as electronics, optics, chemistry, precision instruments, etc., and the cost is low.

[0071] The various parts in this manual are described in a combination of parallel and progressive ways. 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 embodiments in this specification may be replaced or combined with each other, so that professionals in the field can implement or use the present application. Various modifications to these embodiments will be apparent to professionals in the field, 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 will not be limited to the embodiments shown herein, but will 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, used to generate femtosecond laser light, wherein the femtosecond laser light has a polarization direction; A first quartz single crystal sheet and a second quartz single crystal sheet, wherein the crystal plane indexes of the first quartz single crystal sheet and the second quartz single crystal sheet are both (0001), and the first quartz single crystal sheet and the second quartz single crystal sheet are pasted 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 a 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 amplitude of the terahertz wave generated by the quartz single crystal wafer is the largest, and the target azimuth angle is 120° as a period 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 sheet and a second quartz single crystal sheet, wherein the crystal plane indexes of the first quartz single crystal sheet and the second quartz single crystal sheet are both (0001); The first quartz single crystal wafer is placed at a first target azimuth angle, and the second quartz single crystal wafer is placed at a second target azimuth angle, wherein the second target azimuth angle is rotated by 60°, 180°, or 300° relative to the first target azimuth angle; and the first quartz single crystal wafer and the second quartz single crystal wafer are bonded together by using acetone liquid; Among them, when a 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 amplitude of the terahertz wave 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 also 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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