On-chip terahertz amplitude modulator and working method thereof

Abstract

According to the on-chip terahertz amplitude modulator and the working method thereof, a microstrip transmission line is connected with a metal opening resonance ring in series, and an opening is combined with a dynamic material GaAs diode, so that the working mode switching of a resonance unit is supported, and the efficient amplitude modulation of transmitted terahertz waves is realized. According to the on-chip microstrip modulator, a microstrip parallel branch structure adopted by a traditional on-chip microstrip modulator is optimized, efficient modulation is realized by adopting a single modulation unit, and meanwhile, a coding function is introduced for the modulator. The modulation structure is simple, the number of the modulation units is further simplified, the size of the on-chip modulator is reduced, and the modulation structure has the advantages of being high in flexibility and practicability and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic functional devices, and in particular to an on-chip terahertz amplitude modulator and a working method thereof. Background Art

[0002] Terahertz communication, with its abundant spectrum resources and support for Tbps-level data transmission, has shown significant technical advantages in the field of high-speed wireless communications and is expected to serve as the key core of the next generation of wireless communication systems. Direct modulation is the direct application of digital signals to terahertz carriers without the need for microwave and infrared band devices, and has the advantages of compact system architecture and high efficiency. Among them, quasi-optical modulators are mostly based on periodically arranged multi-unit arrays, have many parasitic parameters, and act on transmitted light in free space optical transmission, which is not conducive to the realization of small-scale integration of terahertz systems. Compared with before, on-chip waveguide modulators have achieved high integration and miniaturization by integrating transmission lines and modulation elements on the chip, significantly reducing the impact of parasitic parameters on performance and rate, and providing more stable modulation performance.

[0003] At present, microstrip-based on-chip terahertz communication mostly adopts the form of parallel branches in amplitude modulation. This method produces a small response in the case of a single unit and often cannot meet the requirements of modulation depth. Therefore, multiple modulation units need to be cascaded, which not only increases the overall volume and insertion loss of the modulator, but also poses certain challenges in processing and preparation. Therefore, facing the technical development and application needs in the field of terahertz communication, a modulation structure that is easy to integrate, small in size, highly flexible, and simple in structure is needed. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose an on-chip terahertz amplitude modulator and its working method, which supports the switching of the working mode of the resonant unit by connecting a microstrip transmission line in series with a metal open resonant ring, and combining the opening with a dynamic material GaAs diode, so as to achieve efficient amplitude modulation of the transmitted terahertz wave. The present invention optimizes the microstrip parallel branch structure used in the traditional on-chip microstrip modulator, uses a single modulation unit to achieve efficient modulation, and introduces a codable function to the modulator. At the same time, the modulation structure of the present invention is simple in structure, further simplifies the number of modulation units, reduces the volume of the on-chip modulator, and has the characteristics of flexibility and strong practicality.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] An on-chip terahertz amplitude modulator comprises a substrate, an open resonant ring, a dynamic material GaAs diode and a metal base plate; wherein the substrate is fixed on the metal base plate, the metal base plate is used to provide an electrical boundary for the modulation structure, the surface of the substrate is provided with an open resonant ring and a dynamic material structure, the dynamic material structure is coaxially sleeved on the open resonant ring, the open resonant ring is used to generate a larger resonance in the working frequency band, and the dynamic material structure plays the role of an equivalent modulator switch.

[0007] Furthermore, it also includes a metal microstrip transmission line, which is arranged on the surface of the substrate and connected to the outer side of the open resonant ring. The substrate and the metal microstrip transmission line constitute a 50-ohm standard transmission line.

[0008] Furthermore, the metal microstrip transmission line and the open resonant ring are integrated in series.

[0009] Moreover, the metal base plate provides an environment for the electrical boundary equivalent modulator in actual operation.

[0010] A method for operating an on-chip terahertz amplitude modulator comprises the following steps:

[0011] Step 1: The terahertz carrier is input from one end of the modulator through a metal microstrip transmission line, modulated by the structure of the open resonant ring and the dynamic material, and then output from the other end of the metal microstrip transmission line;

[0012] Step 2: The opening and closing of the dynamic material structure changes the electromagnetic properties at the opening of the open resonant ring, and the on and off of the terahertz wave signal is controlled by changing the impedance of the entire modulation structure.

[0013] The advantages and positive effects of the present invention are:

[0014] 1. The present invention connects a microstrip transmission line in series with a metal open resonant ring, and combines the opening with a dynamic material, thereby supporting the switching of the working mode of the resonant unit and realizing efficient amplitude modulation of the transmitted terahertz wave. The present invention optimizes the microstrip parallel branch structure used in the traditional on-chip microstrip modulator, uses a single modulation unit to achieve efficient modulation, and introduces a codable function to the modulator. The modulation structure of the present invention is simple in structure, further simplifies the number of modulation units, reduces the volume of the on-chip modulator, and has the characteristics of flexibility and strong practicality.

[0015] 2. The present invention connects the resonance unit and the metal microstrip transmission line in series, which has a simple structure and low difficulty in preparation and processing.

[0016] 3. The C-shaped open resonant ring used in the present invention has a large modulation depth, which can support a single unit to effectively modulate the amplitude of the terahertz carrier signal in the target band, thereby reducing the number of modulation units used.

[0017] 4. The present invention can effectively adjust the position of the resonant frequency band and the size of the modulation depth by adjusting the size of the resonant ring and its opening, and has strong plasticity.

[0018] 5. The metal microstrip transmission line structure in the present invention can be realized through a series of traditional photolithography processes, and the process is mature and easy to manufacture.

[0019] 6. The present invention introduces a coding effect into the modulator, thereby improving the function of the modulator;

[0020] 7. The present invention uses a microstrip transmission line to transmit terahertz waves and can operate under normal temperature, normal pressure, and non-vacuum conditions. It is easy to package and convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an overall structural diagram of an on-chip terahertz amplitude modulator and its working method structure of the present invention.

[0022] Figure 2 The present invention is a top view of the structure of an on-chip terahertz amplitude modulator and its working method.

[0023] Figure 3 The S21 parameter diagram of the dynamic material involved in Example 1 of the present invention when the modulator is turned on and off is compared.

[0024] Figure 4 This is a simulation diagram of the electric field of Example 1 of the present invention when the dynamic material is in the open state (coded as the number "1").

[0025] Figure 5 This is an electric field simulation diagram of Example 1 of the present invention when the dynamic material is in the off state (coded as the number "0").

[0026] Figure 6 It is a top view of the dual-band coded modulation structure based on Example 1 of the present invention.

[0027] Figure 7 This is an S21 parameter diagram of the modulator comparison when the dynamic material involved in Example 2 of the present invention is in the four states of "00", "01", "10" and "11".

[0028] Description of reference numerals:

[0029] 1-substrate, 2-metal microstrip transmission line, 3-open resonant ring, 4-structure of dynamic material, 5-metal base plate. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings.

[0031] The present invention solves the technical problem by adopting the following technical solutions:

[0032] An on-chip terahertz amplitude modulator comprises a substrate 1, an open resonant ring 3, a dynamic material GaAs diode 4 and a metal base plate 5; wherein the substrate is fixed on the metal base plate, the metal base plate is used to provide an electrical boundary for the modulation structure, the surface of the substrate is provided with an open resonant ring and a dynamic material structure, the dynamic material structure is coaxially sleeved on the open resonant ring, the open resonant ring is used to generate a larger resonance in the working frequency band, and the dynamic material structure plays the role of an equivalent modulator switch.

[0033] Meanwhile, the present invention also includes a metal microstrip transmission line 2, which is arranged on the surface of the substrate and connected to the outer side of the open resonant ring. The substrate and the metal microstrip transmission line constitute a 50 ohm standard transmission line.

[0034] Among them, the metal microstrip transmission line and the open resonant ring are integrated in series; the size, opening size and position of the open resonant ring are adjustable; at the same time, the structure of the open resonant ring includes but is not limited to a circular ring or a square ring; the open resonant ring and the structure of the dynamic material are integrally formed, and the dynamic material includes but is not limited to a high electron mobility transistor, a gallium arsenide diode or a vanadium oxide.

[0035] The metal base plate provides an environment for the electrical boundary equivalent modulator in actual operation. The material of the metal base plate includes but is not limited to Au, Ag or Cu. The substrate material includes but is not limited to silicon carbide, silicon, indium phosphide or quartz.

[0036] According to the above-mentioned on-chip terahertz amplitude modulator, the following two embodiments are tested to illustrate the effect of the present invention.

[0037] Example 1

[0038] The following is combined with Figure 1-5 The specific embodiment 1 of the present invention is described in detail.

[0039] like Figure 1 and Figure 2 As shown, the present embodiment provides an on-chip terahertz amplitude modulator structure, comprising a substrate, a metal microstrip transmission line, an open resonant ring, a dynamic material structure, and a metal bottom plate. The substrate and the metal microstrip transmission line constitute a 50-ohm standard transmission line; the open resonant ring is used to generate a larger resonance in the working frequency band to increase the transmission loss of the terahertz wave in the working frequency band; the dynamic material structure plays the role of an equivalent modulator switch to realize the on and off of the terahertz wave in the working frequency band; the metal bottom plate provides an electrical boundary for the modulation structure.

[0040] The terahertz carrier is input from one end of the modulator through a metal microstrip transmission line, modulated by the open resonant ring and the dynamic material structure, and then output from the other end of the metal microstrip transmission line. Specifically, the opening and closing of the dynamic material structure can change the electromagnetic properties at the opening of the open resonant ring, thereby changing the overall impedance of the modulation structure and controlling the on and off of the terahertz wave signal.

[0041] In this embodiment, the width of the metal microstrip transmission line is 46 um, and the material of the metal microstrip transmission line is gold; the outer diameter of the open resonant ring is 120 um, the inner diameter is 110 um, and the width of the upper opening is 4 um; at the opening, the size of the dynamic material is 9*4 um, and the thickness of the above structure is 1 um.

[0042] The substrate material is silicon carbide with a thickness of 50 um. The entire open resonant ring is an open C-type ring. The dynamic material is a gallium arsenide diode.

[0043] By changing the on-off switching of the dynamic material, the resonant state of the modulation structure is adjusted, thereby realizing the dynamic regulation of the on-chip terahertz wave. Figure 3 The S21 parameters of the modulator on and off are shown. When the modulator is on, the open diode of the split resonant ring is turned on, the modulation unit is in a low impedance state, and there is no resonance in the range of 0.10-0.17 THz, such as Figure 4 As shown in the figure, the transmission loss is less than 1 dB, and the terahertz wave can pass smoothly in a wide frequency band. When the modulator is in the off state, the split resonant ring generates strong resonance, and the insertion loss is greater than 20 dB in the range of 0.132-0.148 THz, and the modulation depth reaches 48 dB. Figure 5 It can be seen from the figure that the terahertz wave is cut off by the open resonant ring, and the signal insertion loss is large. It can be seen from this that the modulation effect produced by the unit structure is ideal and has a high switching ratio, which illustrates the effectiveness of the invention.

[0044] Example 2

[0045] The following is combined with Figure 6-7 The specific embodiment 2 of the present invention is described in detail.

[0046] like Figure 6 As shown, a top view of an on-chip terahertz amplitude modulator structure provided by this embodiment.

[0047] In this embodiment, the width of the metal microstrip transmission line is 46 um, and the material of the metal microstrip transmission line is gold; the outer diameter of the open resonant ring is 100 um, the inner diameter is 80 um, and the narrow line width at the lower opening connection is 4 um; the width of the upper and lower openings is 4 um; at the upper and lower openings, the sizes of the dynamic materials are 10*4 um and 4*4 um respectively, and the thickness of the above structure is 1 um.

[0048] The substrate material is silicon carbide with a thickness of 50 um. The entire open resonant ring is an open square ring. The dynamic material is a gallium arsenide diode.

[0049] By marking the on and off states of the dynamic material as "1" and "0", there are four different coding combinations, namely "00", "01", "10" and "11". Figure 7 The S21 parameters of the modulator corresponding to four different states are displayed. When the code is "00", the entire modulator is in the disconnected state, and the loss at 0.13 THz and 0.16 THz is greater than 15 dB; when the code is "01", the loss is greater than 20 dB in the range of 0.145-0.166 THz, and the modulation depth is 47 dB; when the code is "10", the loss is greater than 20 dB in the range of 0.122-0.139 THz, and the modulation depth is 41 dB; when the code is "11", the loss of the entire modulator in the range of 0.10-0.17 THz is less than 1 dB, and has good conduction characteristics. It can be seen that the modulation effect of the modulation unit is ideal, and the coding function is added while having a high switching ratio, which illustrates the effectiveness of the invention.

[0050] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. An on-chip terahertz amplitude modulator, characterized in that: It includes a substrate, an open resonant ring, a dynamic material GaAs diode and a metal base plate; wherein the substrate is fixed on the metal base plate, the metal base plate is used to provide an electrical boundary for the modulation structure, the surface of the substrate is provided with an open resonant ring and a dynamic material GaAs diode structure, the dynamic material structure is coaxially sleeved on the open resonant ring, the open resonant ring is used to generate resonance in the working frequency band, and the dynamic material structure plays the role of an equivalent modulator switch.

2. The on-chip terahertz amplitude modulator according to claim 1, characterized in that: It also includes a metal microstrip transmission line, which is arranged on the surface of the substrate and connected to the outer side of the open resonant ring. The substrate and the metal microstrip transmission line form a 50-ohm standard transmission line.

3. The on-chip terahertz amplitude modulator according to claim 2, characterized in that: The metal microstrip transmission line and the open resonant ring are integrated in series.

4. The on-chip terahertz amplitude modulator according to claim 1, characterized in that: The metal base plate provides an environment for the electrical boundary equivalent modulator in actual operation.

5. A method for operating an on-chip terahertz amplitude modulator according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: The terahertz carrier is input from one end of the modulator through a metal microstrip transmission line, modulated by the structure of the open resonant ring and the dynamic material, and then output from the other end of the metal microstrip transmission line; Step 2: The opening and closing of the structure of the dynamic material GaAs diode realizes the change of the electromagnetic properties at the opening of the open resonant ring, and controls the on and off of the terahertz wave signal by changing the impedance of the entire modulation structure.

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