A terahertz modulator

Abstract

The present invention provides a terahertz modulator, comprising a substrate, a first electrode, a second electrode and a voltage and current source; the substrate comprises a first surface and a second surface opposite to each other, the first electrode is arranged on the first surface, and the second electrode is arranged on the second surface; the positive output terminal of the voltage and current source is electrically connected to the first electrode, and the negative output terminal is electrically connected to the second electrode. The terahertz modulator provided by the present invention causes the substrate to enter an avalanche breakdown state through the voltage and current source, thereby realizing a great change in the conductivity of the substrate material, and then causes a great change in the carrier concentration by adjusting the current, and controls the transmittance of the terahertz wave by adjusting the magnitude of the output current, thereby realizing the modulation of the terahertz wave, and utilizing the avalanche breakdown to realize a higher modulation depth, thereby realizing the dynamic adjustability of the modulator.

Description

Technical Field

[0001] The present application relates to the technical field of terahertz wave modulation, and in particular to a terahertz modulator. Background Art

[0002] Terahertz (THz, 1THz = 1024Hz) waves refer to the electromagnetic spectrum region between millimeter waves and infrared optics with a frequency range of 0.1-10THz and a corresponding wavelength of 3mm-30μm. With the development of modern science and technology, people's research on millimeter waves and infrared light has continued to deepen, and their devices and application technologies have become increasingly mature, forming two major application and research fields of millimeter waves and infrared optics.

[0003] When using terahertz waves, it is necessary to modulate the terahertz waves. Modulating the terahertz waves refers to adjusting the terahertz wave transmittance of the device. Existing terahertz modulation devices have poor modulation effects and small modulation depths, and cannot meet modulation requirements. Summary of the invention

[0004] In view of this, the present application provides a terahertz modulator to improve the problem that existing terahertz modulation devices cannot meet modulation requirements.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The present invention provides a terahertz modulator, which comprises: a substrate, a first electrode, a second electrode and a voltage-current source; the substrate comprises a first surface and a second surface opposite to each other, the first electrode is arranged on the first surface, and the second electrode is arranged on the second surface; the voltage-current source comprises a positive output terminal and a negative output terminal, the positive output terminal is electrically connected to the first electrode, and the negative output terminal is electrically connected to the second electrode; the voltage-current source is used to adjust the voltage output to the substrate so that the substrate enters an avalanche breakdown state; the voltage-current source is also used to convert into a current source when the substrate enters an avalanche breakdown state, and adjust the current output to the substrate to adjust the terahertz wave transmittance of the substrate.

[0007] Furthermore, a rated current of the voltage-current source is greater than an avalanche breakdown current of the substrate.

[0008] Furthermore, the thickness of the substrate is less than 1000 μm.

[0009] Furthermore, the thickness of the substrate is 300 μm.

[0010] Furthermore, the resistivity of the substrate is less than 100Ω·cm.

[0011] Furthermore, the thickness of the first electrode and the second electrode is 200 μm.

[0012] Furthermore, the first electrode is a strip electrode or a ring electrode.

[0013] Furthermore, the second electrode is a ring electrode or a strip electrode.

[0014] Furthermore, the material of the substrate includes one of P-type silicon, N-type silicon, germanium or gallium arsenide.

[0015] Compared with the prior art, the terahertz modulator provided by the present application has the following beneficial effects:

[0016] The terahertz modulator provided by the present application includes a substrate, a first electrode, a second electrode and a voltage and current source; a voltage is applied to the substrate material by using the voltage and current source, so that the substrate is converted from a non-avalanche breakdown state to an avalanche breakdown state. After the substrate enters the avalanche breakdown state, the current on the device is adjusted by the voltage and current source, thereby realizing the modulation of the terahertz wave. The larger the current, the lower the transmittance of the terahertz wave, and the smaller the current, the higher the transmittance of the terahertz wave. By using a voltage and current source, the voltage and current source is a voltage source when the substrate is not broken down, and when the substrate breaks down, it acts as a current source, thereby realizing the dynamic adjustment of the current, adjusting the transmittance of the terahertz wave, and realizing the modulation of the terahertz wave.

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of a terahertz modulator provided by the present invention is shown.

[0020] Figure 2 A first viewing angle view of the terahertz modulator provided by the present invention is shown.

[0021] Figure 3 A second viewing angle view of the terahertz modulator provided by the present invention is shown.

[0022] Figure 4 A third viewing angle view of the terahertz modulator provided by the present invention is shown.

[0023] Figure 5 A schematic diagram of the IV curve of the substrate material is shown.

[0024] Icon: 100 - terahertz modulator; 110 - substrate; 111 - first surface; 112 - second surface; 120 - first electrode; 130 - second electrode; 140 - voltage and current source; 141 - positive output terminal; 142 - negative output terminal. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0027] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0028] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly stipulated and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0029] In the description of the present invention, it should also be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Terms such as "horizontal", "vertical", "overhanging" and the like do not mean that the components are absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. The terms "include", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0030] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0031] Terahertz waves refer to electromagnetic waves with a frequency range of 0.1THz to 10THz and a wavelength of approximately 0.03 to 3mm, which is between microwaves and infrared. With the development of modern science and technology, people's research on millimeter waves and infrared light has continued to deepen, and their devices and application technologies have become increasingly mature, forming two major application and research fields of millimeter waves and infrared optics. When using terahertz waves, it is necessary to modulate the terahertz waves. Modulating terahertz waves refers to adjusting the terahertz wave transmittance of the device. The existing terahertz modulation devices have poor modulation effects and small modulation depths, which cannot meet the modulation requirements.

[0032] In order to improve the above problems, the present application provides a terahertz modulator 100. Figure 1 to Figure 4 , Figure 1 The structure diagram of the terahertz modulator 100 provided in an embodiment of the present application is shown. The terahertz modulator 100 provided in this embodiment includes a substrate 110, electrodes and a voltage and current source 140. The substrate 110 includes a first surface 111 and a second surface 112 opposite to each other, and the electrodes include a first electrode 120 and a second electrode 130, wherein the first electrode 120 is disposed on the first surface 111, and the second electrode 130 is disposed on the second surface 112.

[0033] The voltage-current source 140 includes a positive output terminal 141 and a negative output terminal 142 , wherein the positive output terminal 141 is electrically connected to the first electrode 120 , and the negative output terminal 142 is electrically connected to the second electrode 130 .

[0034] The voltage-current source 140 is used to apply an electrical signal to the substrate 110, and adjust the voltage applied to the substrate 110 to convert the substrate 110 material from a non-avalanche breakdown state to an avalanche breakdown state. After the substrate 110 material is converted to the avalanche breakdown state, the voltage-current source 140 is used to adjust the output current, adjust the carrier concentration of the substrate 110, and adjust the resistivity of the substrate 110, thereby controlling the transmittance of the terahertz wave and realizing the modulation of the terahertz wave.

[0035] The terahertz modulator 100 provided in this embodiment utilizes the avalanche breakdown characteristics of the substrate 110 material. The voltage and current source 140 is used to first make the substrate 110 material enter an avalanche breakdown state. After the substrate 110 material enters the avalanche breakdown state, the voltage and current source 140 is used to adjust the current applied to both ends of the substrate 110 material to achieve dynamic current adjustment. By making the substrate 110 material work in an avalanche breakdown state, a great change in the conductivity of the substrate 110 material is achieved, thereby causing a great change in the carrier concentration. By adjusting the current applied to both ends of the substrate 110 material to adjust the carrier concentration, the transmittance of the terahertz wave is adjusted, and the modulation of the transmittance of the terahertz wave is achieved.

[0036] The material of the substrate 110 may be a material with a low resistivity, for example, a material with a resistivity less than 100Ω·cm, preferably, a material with a resistivity of 10-15Ω·cm. In a possible implementation, the material of the substrate 110 may be a P-type Si material, an N-type Si material, germanium, gallium arsenide, and the like. In this embodiment, the substrate 110 is a P-type Si material, but is not limited thereto.

[0037] The shape of the substrate 110 may be a rectangle, a square, a circle or other shapes, which is not limited in this embodiment. For example, in a possible implementation, the shape of the substrate 110 is set to be a square. In order to facilitate the terahertz modulator 100 to be set in an integrated circuit, generally, the volume of the substrate 110 should not be too large. For example, the size of the substrate 110 is set to be 12 mm in length and width, and 300 μm in thickness, that is, the length and width of the first surface 111 and the second surface 112 are both set to 12 mm, and the thickness between the first surface 111 and the second surface 112 is 300 μm.

[0038] It should be noted that since the thickness and resistivity of the substrate 110 material may affect the avalanche breakdown voltage, the resistivity of the selected substrate 110 material should not be too large. Generally, a material with a resistivity less than 100Ω·cm can be selected. The thickness of the substrate 110 should not be too large. Generally speaking, the thickness of the selected substrate 110 material is less than 1000μm.

[0039] The electrodes include a first electrode 120 and a second electrode 130 . The first electrode 120 is disposed on the first surface 111 ; the second electrode 130 is disposed on the second surface 112 . The voltage and current source 140 applies a current or voltage to the substrate 110 through the first electrode 120 and the second electrode 130 .

[0040] The electrode is arranged on the surface of the substrate 110, and forms a good electrical contact with the substrate 110. It should be noted that, since the material of the substrate 110 is very easy to react with oxygen in the air to form an oxide layer, in order to prevent the electrode from having a poor contact with the substrate 110, the oxide layer on the surface of the substrate 110 needs to be removed before the electrode is arranged. For example, in a possible implementation, the substrate 110 is made of P-type Si, and a layer of SiO2 will be formed on the surface of the substrate 110. Before the electrode is arranged, the SiO2 on the surface of the substrate 110 needs to be removed to make the electrode have a good contact with the substrate 110 and improve the conductive performance.

[0041] In a possible implementation, the first electrode 120 may be provided as a strip electrode, and the number of the strip electrodes is one or more. When the number of the strip electrodes is one, the strip electrode may be provided in the central area of ​​the first surface 111; when the number of the strip electrodes is multiple, the strip electrodes may be uniformly arranged on the first surface 111. Providing multiple strip electrodes may enable the terahertz modulator 100 to be installed and used without being restricted by an installation angle.

[0042] The first electrode 120 is used to connect to the positive output terminal 141 of the voltage-current source 140 . In another possible implementation, the first electrode 120 may also be used to connect to the negative output terminal 142 of the voltage-current source 140 .

[0043] In a possible implementation manner, the length of the strip electrode may be set to 10 mm, the width to 2 mm, and the thickness to 200 nm.

[0044] The second electrode 130 can be an annular electrode, and the annular electrode is arranged on the second surface 112. Similarly, when setting the second electrode 130, the oxide layer of the second surface 112 needs to be removed. For example, in one possible implementation, the substrate 110 is made of P-type-Si, and a layer of SiO2 will be formed on the second surface 112. Before setting the second electrode 130, the SiO2 on the second surface 112 needs to be removed to ensure that the second electrode 130 is in good contact with the second surface 112 of the substrate 110 to improve the conductivity.

[0045] The second electrode 130 is used to connect the negative output terminal 142 of the voltage-current source 140, but is not limited to this. In one possible implementation, the first electrode 120 is connected to the positive output terminal 141 of the voltage-current source 140, and the second electrode 130 is used to connect the negative output terminal 142 of the voltage-current source 140; in another possible implementation, the first electrode 120 is connected to the negative output terminal 142 of the voltage-current source 140, and the second electrode 130 is used to connect the positive output terminal 141 of the voltage-current source 140.

[0046] In a possible implementation, the outer ring width of the second electrode 130 is 12 mm, the ring width is 2 mm, and the thickness is 200 mm.

[0047] It should be noted that the above examples of the shape, parameters, etc. of the first electrode 120 and the second electrode 130 are not limitations of this embodiment. The first electrode 120 and the second electrode 130 can also be other shapes. For example, the first electrode 120 can also be a ring electrode, and the second electrode 130 can also be a strip electrode. This embodiment does not limit this.

[0048] The first electrode 120 and the second electrode 130 are both made of a material with good conductivity. For example, in a possible implementation, the first electrode 120 and the second electrode 130 are both made of titanium (TiAu), but not limited thereto. The electrode can be plated on the substrate 110 using a photolithography process. In other implementations of this embodiment, the electrode can also be arranged using other processes.

[0049] In a possible implementation, the first electrode 120 and the second electrode 130 may be respectively connected to a wire for easy wiring; the first electrode 120 and the second electrode 130 may also not be connected to a wire, but may be electrically connected to the power supply through other methods, such as welding or other methods.

[0050] In this embodiment, the power source is a voltage and current source 140. The voltage and current source 140 can first be used as a current source to adjust the voltage to increase the voltage and current; when the current reaches the set rated current, the substrate 110 undergoes avalanche breakdown, and the voltage and current source 140 is transformed into a current source. At this time, the voltage is not adjustable, but the current is adjustable. By adjusting the current applied to the substrate 110 material, the carrier concentration of the substrate 110 material is changed, and the conductivity of the substrate 110 is changed, thereby realizing the modulation of the terahertz wave transmittance.

[0051] It should be noted that the above modulation can only be performed after the substrate 110 material undergoes avalanche breakdown. Avalanche breakdown refers to the situation in which, in a PN junction with a low material doping concentration, the electric field in the space charge region increases as the reverse voltage of the PN junction increases. In this way, the electrons and holes passing through the space charge region will increase the energy obtained under the action of the electric field. The electrons and holes running in the crystal will constantly collide with the crystal atoms. Through such collisions, the valence electrons bound in the covalent bonds can collide out and generate free electron-hole pairs. The newly generated carriers knock out other valence electrons under the action of the electric field, and new free electron and hole pairs are generated. Such a chain reaction causes the number of carriers in the barrier layer to increase in an avalanche manner, and the current flowing through the PN junction increases sharply and breaks down the PN junction. This collision ionization leads to breakdown, which is called avalanche breakdown.

[0052] When setting the rated current of the voltage-current source 140, the rated current needs to be greater than the avalanche breakdown current that causes the substrate 110 material to enter an avalanche breakdown state. In a possible implementation, the avalanche breakdown current of the substrate 110 material is related to its thickness. The current of the avalanche breakdown of the substrate 110 material with a thickness of 300 μm selected in this embodiment is about 0.2A, so the rated current of the voltage-current source 140 needs to be greater than 0.2A. For example, it can be set to 0.5A. In other implementations of this embodiment, the rated current needs to be set according to the substrate 110. At the same time, in order to prevent excessive current from damaging the device, the rated current needs to be less than 1A.

[0053] In a possible implementation, if a substrate 110 material of other thickness is selected, a voltammetry test can be performed in advance based on the substrate 110 material to measure the current and voltage when the substrate 110 material is in an avalanche breakdown state, so as to adjust the parameters of the voltage-current source 140 according to the measured current or voltage. For example, see Figure 5 , Figure 5The IV curve measured for silicon with a thickness of 300 μm is shown. By gradually increasing the voltage applied to both ends of the silicon and detecting its current in real time, it can be obtained that as the voltage increases, the current gradually increases nonlinearly and finally reaches avalanche breakdown, so that its avalanche breakdown current and voltage can be determined. The terahertz modulator 100 provided in this embodiment is regulated in the avalanche zone.

[0054] Avalanche breakdown can also be achieved by using a simple voltage source, but after avalanche breakdown, the current applied to the substrate 110 material cannot be accurately controlled, and the current cannot be dynamically adjustable, so the modulation of the terahertz wave cannot be achieved. This embodiment uses a voltage and current source 140, and adjusts the voltage to convert the substrate 110 material from a non-avalanche breakdown state to an avalanche breakdown state. When the substrate 110 material is converted to the avalanche breakdown state, the voltage and current source 140 controls the transmittance of the terahertz wave by adjusting the magnitude of the output current, thereby achieving the modulation of the terahertz wave. The lower the resistivity of the substrate 110 material, the lower the transmittance of the terahertz wave. By causing the substrate 110 material to undergo avalanche breakdown, a great change in the conductivity of the substrate 110 material is achieved, thereby causing a great change in the carrier concentration, thereby achieving a great modulation of the transmittance of the terahertz wave. In this embodiment, the terahertz wave transmission energy modulation degree can reach 99.99%.

[0055] In summary, the present invention provides a terahertz modulator, including a substrate, a first electrode, a second electrode and a voltage and current source; the substrate includes a first surface and a second surface opposite to each other, the first electrode is arranged on the first surface, and the second electrode is arranged on the second surface; the voltage and current source includes a positive output terminal and a negative output terminal, the positive output terminal is electrically connected to the first electrode, and the negative output terminal is electrically connected to the second electrode; the voltage and current source is used to adjust the voltage output to the substrate so that the substrate enters an avalanche breakdown state; the voltage and current source is also used to convert into a current source when the substrate enters an avalanche breakdown state, and adjust the current output to the substrate to adjust the terahertz wave transmittance of the substrate. The terahertz modulator provided by the present invention causes the substrate to enter an avalanche breakdown state through a voltage and current source, thereby realizing a great change in the conductivity of the substrate material, and then causes a great change in the carrier concentration by adjusting the current, and controls the transmittance of the terahertz wave by adjusting the magnitude of the output current, thereby realizing the modulation of the terahertz wave, and utilizing avalanche breakdown to realize a higher modulation depth, thereby realizing the dynamic adjustability of the modulator.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A terahertz modulator, characterized in that: The terahertz modulator comprises: a substrate, a first electrode, a second electrode and a voltage and current source; The substrate comprises a first surface and a second surface opposite to each other, the first electrode is disposed on the first surface, and the second electrode is disposed on the second surface; The voltage-current source comprises a positive output terminal and a negative output terminal, the positive output terminal is electrically connected to the first electrode, and the negative output terminal is electrically connected to the second electrode; The voltage-current source is used to adjust the voltage output to the substrate so that the substrate enters an avalanche breakdown state; the voltage-current source is also used to convert into a current source when the substrate enters an avalanche breakdown state, and adjust the current output to the substrate to adjust the terahertz wave transmittance of the substrate.

2. The terahertz modulator according to claim 1, characterized in that: The rated current of the voltage-current source is greater than the avalanche breakdown current of the substrate.

3. The terahertz modulator according to claim 1, characterized in that: The thickness of the substrate is less than 1000 μm.

4. The terahertz modulator according to claim 1, characterized in that: The thickness of the substrate is 300 μm.

5. The terahertz modulator according to claim 1, characterized in that: The resistivity of the substrate is less than 100 Ω·cm.

6. The terahertz modulator according to claim 1, characterized in that: The thickness of the first electrode and the second electrode is 200 μm.

7. The terahertz modulator according to claim 1, characterized in that: The first electrode is a strip electrode or a ring electrode.

8. The terahertz modulator according to claim 1, characterized in that: The second electrode is a ring electrode or a strip electrode.

9. The terahertz modulator according to claim 1, characterized in that: The material of the substrate includes one of P-type silicon, N-type silicon, germanium or gallium arsenide.

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