G-band terahertz photoelectric mixing module based on WR5.1 metal waveguide packaging

Abstract

The invention provides a G-band terahertz photoelectric mixing module based on WR5.1 metal waveguide packaging, which is characterized by comprising a WR5.1 waveguide cavity structure composed of a metal upper base and a metal lower base, one end of the WR5.1 waveguide cavity structure is provided with an SMA coaxial interface, a single-mode optical fiber collimator is exposed out of the other end of the WR5.1 waveguide cavity structure, and the other end of the single-mode optical fiber collimator is provided with an SMA coaxial interface. The single-mode fiber collimator and a micro lens located in the WR5.1 waveguide cavity structure form an optical focusing system, and an MUTC-PD, a quartz-based radio frequency circuit board and a direct-current power supply expansion board are further arranged in the WR5.1 waveguide cavity structure; the DC power supply expansion board is connected with the quartz-based radio frequency circuit board and the SMA coaxial interface, the quartz-based radio frequency circuit board is connected with the MUTC-PD, and the lens focus of the micro lens is on the waveguide cleavage plane of the MUTC-PD. According to the technical scheme disclosed by the invention, the problems of low integration level, large transmission link loss, high processing difficulty and the like of a radio frequency circuit in the prior art can be solved, and high-power terahertz signal output is realized.

Description

Technical Field

[0001] The invention relates to a G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide packaging, belonging to the technical field of MUTC-PD terahertz emission modules. Background Art

[0002] In recent years, terahertz (100GHz~10THz) technology has shown broad application prospects in the fields of wireless communication, high-resolution imaging and sensing. Traditional methods of generating terahertz signals mainly include electrical and optical methods. The electrical method includes signal generation methods based on frequency doubling and mixing technology, but this method usually has defects such as narrow frequency band, multiple harmonics and low transmission rate. In contrast, the use of optical heterodyne beat frequency technology to generate terahertz signals with the help of modified single carrier transfer photodetector (MUTC-PD) has the advantages of large bandwidth, no harmonics and high transmission rate. Therefore, optically generated terahertz sources have become an important development direction in terahertz technology.

[0003] In practical applications, when the frequency exceeds 100 GHz, MUTC-PD packaged with coaxial connectors faces challenges in achieving low-loss output, including dielectric loss, high-order modes, electromagnetic interference, etc. In contrast, waveguides can provide low-loss output over a wide frequency range and can be easily integrated with other standard waveguide interface devices (such as antennas, amplifiers, mixers, etc.).

[0004] In the existing MUTC-PD waveguide packaging module, branch bias is usually used to provide DC power supply and RF current suppression. However, as the frequency increases (for example, G band: 140GHz~220GHz), the RF circuit needs to reduce the loss by using low dielectric constant materials (such as quartz) and reducing the size. The three design methods adopted by the branch bias method will increase the RF loss or the difficulty of processing and assembly to a certain extent:

[0005] 1. Integrate the circuit on a board without additional cutting: This method will greatly increase the geometric size of the circuit board and thus increase the RF loss. The RF loss can be reduced by drilling holes in the board, but it will undoubtedly increase the processing difficulty and cost.

[0006] 2. Integrate the circuit on a board and cut off the excess parts: This method will greatly increase the difficulty of cutting and assembly. When the size is small (for example: 50 microns thick and 320 microns wide), it is not suitable for high-quality, low-loss performance boards such as quartz-based.

[0007] 3. Printing the branch circuit and the RF main circuit separately and bonding them together will increase the RF loss and assembly difficulty.

[0008] An unreasonable backshort design of the waveguide component will also lead to increased loss of high-frequency signals and affect the system bandwidth performance, which is usually not taken into consideration in traditional module design.

[0009] Existing, traditional excitation probes are generally rectangular in shape, and lack structural exploration of the excitation probes, resulting in limited working bandwidth. Summary of the invention

[0010] The purpose of the present invention is to solve the problem of low output power of existing G-band photogenerated terahertz sources by comprehensively considering impedance matching, high integration and low loss to design a transmission link.

[0011] In order to achieve the above-mentioned purpose, the technical solution of the present invention is to disclose a G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package, characterized in that it includes a WR5.1 waveguide cavity structure composed of a metal upper base and a lower base, one end of the WR5.1 waveguide cavity structure is provided with an SMA coaxial interface, a single-mode fiber collimator is exposed outside the other end of the WR5.1 waveguide cavity structure, the single-mode fiber collimator and a microlens located in the WR5.1 waveguide cavity structure form an optical focusing system, and the WR5.1 waveguide cavity structure is also provided with a MUTC-PD, a quartz-based RF circuit board and a DC power supply extension board; the DC power supply extension board is connected to the quartz-based RF circuit board and the SMA coaxial interface, the quartz-based RF circuit board is connected to the MUTC-PD, and the lens focus of the microlens is on the waveguide cleavage surface of the MUTC-PD.

[0012] Preferably, the quartz-based RF circuit board includes a GCPW input transmission line with characteristic impedance matching, an improved ultra-wideband sector excitation probe, and an on-chip integrated stepped impedance low-pass filter, wherein:

[0013] The characteristic impedance-matched GCPW input transmission line is used to connect the MUTC-PD as the input end of the signal;

[0014] The improved ultra-wideband sector excitation probe is used to excite the TE10 waveguide of the WR5.1 waveguide;

[0015] The on-chip integrated stepped impedance low-pass filter is used to provide a DC bias voltage for the MUTC-PD and to suppress RF signal leakage.

[0016] Preferably, the quartz-based radio frequency circuit board uses 50 micron thick quartz as a carrier board.

[0017] Preferably, the GCPW input transmission line, the improved ultra-wideband sector excitation probe, and the on-chip integrated stepped impedance low-pass filter are distributed in a straight line along the quartz-based RF circuit board.

[0018] Preferably, the characteristic impedance of the characteristic impedance-matched GCPW input transmission line is 50 ohms.

[0019] Preferably, the on-chip integrated stepped impedance low-pass filter is composed of periodically arranged microstrip lines with widths of 280 microns and 20 microns.

[0020] Preferably, the DC power supply expansion board uses 150 micron thick quartz as a substrate, on which connection metal pads are printed for connecting with the on-chip integrated stepped impedance low-pass filter and the SMA coaxial interface.

[0021] Preferably, the upper waveguide component of the metal upper base cooperates with the lower waveguide component of the metal lower base to form an output waveguide interface, the waveguide interface form is WR5.1, and the working frequency band covers 140GHz~220GHz; the short ends of the upper waveguide component and the lower waveguide component are chamfered by 320 microns to reduce high-frequency return loss, and the far end is a standard WR5.1 waveguide output port.

[0022] Preferably, the upper waveguide component of the metal upper base is provided with an upper transmission component 1 and an upper transmission component 2 on both sides, and the lower waveguide component of the metal lower base is provided with a lower transmission component 1 and a lower transmission component 2 on both sides;

[0023] The characteristic impedance-matched GCPW input transmission line is placed in a transmission cavity 1 composed of an upper transmission component 1 and a lower transmission component 1, and the metal lower base and the ground line of the GCPW input transmission line are connected to form a common ground through conductive silver glue;

[0024] The on-chip integrated stepped impedance low-pass filter is placed in a transmission cavity 2 composed of an upper transmission component 2 and a lower transmission component 2;

[0025] The quartz-based RF circuit board and the DC power supply expansion board are gold-plated on the front side, and 10 microns thick conductive silver glue is applied on the back side to be fixed to the metal lower base, wherein the DC power supply expansion board is placed on the lower bearing component 1 of the metal lower base;

[0026] The MUTC-PD is fixed on the lower bearing table of the metal lower base by UV glue, and the upper surface of the MUTC-PD is flush with the upper surface of the quartz-based radio frequency circuit board.

[0027] The single-mode optical fiber collimator is fixed in the lower bearing component 2 of the metal lower base by UV glue;

[0028] The microlens is fixed on the lower bearing component 3 of the metal lower base by UV glue;

[0029] The SMA coaxial interface is inserted into the lower bearing component 4 of the metal lower base and fixed with screws.

[0030] Preferably, the MUTC-PD is bonded to the GCPW input transmission line with gold wire, the quartz-based RF circuit board is connected to the DC power supply expansion board with conductive silver glue, and the DC power supply expansion board and the SMA coaxial interface are connected with conductive silver glue.

[0031] The technical solution disclosed in the present invention can solve the problems of low integration of radio frequency circuits, large transmission link loss, high processing difficulty, etc. in the prior art, and realize high-power terahertz signal output. Compared with the prior art solution, the present invention has the following beneficial effects:

[0032] Integrated design of linear bias circuit in the same direction: Different from the traditional branch bias scheme, the present invention adopts a linear layout design of the GCPW input transmission line with characteristic impedance matching, an improved ultra-wideband fan-shaped excitation probe, and an on-chip integrated stepped impedance low-pass filter in the same direction. This design significantly solves the problems of low integration of RF circuits and large transmission link loss.

[0033] Waveguide backshort optimization design: By improving the waveguide backshort structure and using 320-micron chamfering, the return loss at high frequencies is effectively reduced and the bandwidth characteristics of the system are improved.

[0034] The metal lower base and the ground wire of the GCPW input transmission line are connected to form a common ground through conductive silver glue, eliminating the process step of drilling through holes on the chip, greatly reducing the processing difficulty while also achieving the effect of low-loss transmission.

[0035] The geometric shape of the excitation probe was designed and optimized, and an improved ultra-wideband fan-shaped excitation probe was proposed, so that the insertion loss of the entire transmission link in the G band is controlled within 0.5dB±0.3dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the appearance and structure of the G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package;

[0037] Figure 2 This is a schematic diagram of the internal design structure of the cavity;

[0038] Figure 3 This is a schematic diagram of the interior of the metal lower base;

[0039] Figure 4 This is a schematic diagram of the interior of the metal upper base;

[0040] Figure 5 The diagram shows the MUTC-PD, quartz-based RF circuit and DC power supply expansion board. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0042] like Figure 1 , 2 As shown in Figures 3 and 4, the G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package disclosed in this embodiment includes: a WR5.1 waveguide cavity structure composed of a metal upper base 1 and a metal lower base 2, an SMA coaxial interface 3, an optical focusing system composed of a single-mode fiber collimator 4 and a microlens 5, a MUTC-PD 6, a quartz-based RF circuit board 7 placed in the metal lower base 2, and a DC power supply expansion board 8.

[0043] like Figure 1 , 3 As shown in FIG. 4 , the waveguide cavity structure is composed of a metal upper base 1 and a metal lower base 2. The short end (backshort) 206 of the waveguide component is chamfered by 320 microns to reduce high-frequency return loss, and the far end is a standard WR5.1 waveguide output port. The metal upper base 1 and the metal lower base 2 are made of copper, and aluminum can be selected in other embodiments. First, precision CNC milling is performed by a precision machine tool, and then the surface is gold-plated.

[0044] like Figure 3 , 4 As shown, the waveguide component 101 of the metal upper base 1 cooperates with the waveguide component 201 of the metal lower base 2 to form an output waveguide interface. The interface type is WR5.1, and the working frequency band covers 140GHz to 220GHz.

[0045] like Figure 5 As shown, the quartz-based RF circuit board 7 uses 50-micron-thick quartz as a carrier board, including: a characteristic impedance-matched GCPW input transmission line 701 (characteristic impedance is 50 ohms), an improved ultra-wideband fan-shaped excitation probe 702, and an on-chip integrated step impedance low-pass filter 703, and they are distributed in a straight line along the quartz-based RF circuit board 7. The characteristic impedance-matched GCPW input transmission line 701 is used to connect the MUTC-PD 6 as the input end of the signal. The improved ultra-wideband fan-shaped excitation probe 702 is used to excite the TE10 waveguide of the WR5.1 waveguide. The on-chip integrated step impedance low-pass filter 703 is used to provide a DC bias voltage for the MUTC-PD 6 and curb RF signal leakage, and is composed of a periodic arrangement of microstrip lines with widths of 280 microns and 20 microns.

[0046] The DC power supply expansion board 8 uses 150 micron thick quartz as a substrate, on which a connection metal pad 801 is printed for connecting with the on-chip integrated stepped impedance low-pass filter 703 and the SMA coaxial interface 3 .

[0047] like Figure 2 , 3 As shown in Figure 4, the quartz-based RF circuit board 7 and the DC power supply expansion board 8 are gold-plated on the front side, and a 10-micron-thick conductive silver glue is applied on the back side to fix them to the metal lower base 2. The characteristic impedance-matched GCPW input transmission line 701 is placed in the transmission cavity composed of the transmission component 103 of the metal upper base 1 and the transmission component 205 of the metal lower base 2, and the ground wires of the metal lower base 2 and the GCPW input transmission line 701 are connected to form a common ground through the conductive silver glue. The on-chip integrated step impedance low-pass filter 703 is placed in the transmission cavity composed of the transmission component 102 of the metal upper base 1 and the transmission component 207 of the metal lower base 2. The DC power supply expansion board 8 is placed on the bearing component 208 of the metal lower base 2. The MUTC-PD 6 is fixed on the bearing table 204 of the metal lower base 2 with UV glue, and the upper surface of the MUTC-PD 6 is flush with the upper surface of the quartz-based RF circuit board 7.

[0048] The single-mode fiber collimator 4 is fixed to the bearing assembly 202 of the metal lower base 2 with UV glue. The SMA coaxial interface 3 is inserted into the bearing assembly 209 of the metal lower base 2 and fixed with screws. The microlens 5 is fixed to the bearing assembly 203 of the metal lower base 2 with UV glue, and the lens focus is on the waveguide cleavage surface of the MUTC-PD 6. The MUTC-PD 6 and the GCPW input transmission line 701 are bonded with gold wire, the quartz-based RF circuit board 7 and the DC power supply expansion board 8 are connected with conductive silver glue, and the DC power supply expansion board 8 and the SMA coaxial interface 3 are connected with conductive silver glue.

Claims

1. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package, characterized in that: It includes a WR5.1 waveguide cavity structure composed of a metal upper base and a lower base. An SMA coaxial interface is provided at one end of the WR5.1 waveguide cavity structure. A single-mode fiber collimator is exposed outside the other end of the WR5.1 waveguide cavity structure. The single-mode fiber collimator and a microlens located in the WR5.1 waveguide cavity structure form an optical focusing system. A MUTC-PD, a quartz-based RF circuit board and a DC power supply expansion board are also provided in the WR5.1 waveguide cavity structure. The DC power supply expansion board is connected to the quartz-based RF circuit board and the SMA coaxial interface, the quartz-based RF circuit board is connected to the MUTC-PD, and the lens focus of the microlens is on the waveguide cleavage surface of the MUTC-PD.

2. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package as claimed in claim 1, characterized in that: The quartz-based radio frequency circuit board includes a characteristic impedance-matched GCPW input transmission line, an improved ultra-wideband sector-shaped excitation probe, and an on-chip integrated stepped impedance low-pass filter, wherein: The characteristic impedance matched GCPW input transmission line is used to connect the MUTC-PD as the input end of the signal; The improved ultra-wideband sector excitation probe is used to excite the TE10 waveguide of the WR5.1 waveguide; The on-chip integrated stepped impedance low-pass filter is used to provide a DC bias voltage for the MUTC-PD and to suppress RF signal leakage.

3. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package as claimed in claim 2, characterized in that: The quartz-based radio frequency circuit board uses 50-micron-thick quartz as a carrier board.

4. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package as claimed in claim 2, characterized in that: The GCPW input transmission line, the improved ultra-wideband sector-shaped excitation probe, and the on-chip integrated stepped impedance low-pass filter are distributed in a straight line along the quartz-based radio frequency circuit board.

5. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package as claimed in claim 2, characterized in that: The characteristic impedance of the characteristic impedance-matched GCPW input transmission line is 50 ohms.

6. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package as claimed in claim 2, characterized in that: The on-chip integrated stepped impedance low-pass filter is composed of periodically arranged microstrip lines with widths of 280 microns and 20 microns.

7. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide packaging as claimed in claim 2, characterized in that: The DC power supply expansion board uses 150 micron thick quartz as a carrier, on which connection metal pads are printed for connecting with the on-chip integrated stepped impedance low-pass filter and the SMA coaxial interface.

8. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide packaging as claimed in claim 7, characterized in that: The output waveguide interface is composed of the upper waveguide component of the metal upper base and the lower waveguide component of the metal lower base. The waveguide interface is in the form of WR5.1, and the operating frequency band covers 140GHz to 220GHz. The short ends of the upper waveguide component and the lower waveguide component are chamfered by 320 microns to reduce high-frequency return loss, and the far end is a standard WR5.1 waveguide output port.

9. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package as claimed in claim 8, characterized in that: The upper waveguide component of the metal upper base is provided with an upper transmission component 1 and an upper transmission component 2 on both sides, and the lower waveguide component of the metal lower base is provided with a lower transmission component 1 and a lower transmission component 2 on both sides; The characteristic impedance-matched GCPW input transmission line is placed in a transmission cavity 1 composed of an upper transmission component 1 and a lower transmission component 1, and the metal lower base and the ground line of the GCPW input transmission line are connected to form a common ground through conductive silver glue; The on-chip integrated stepped impedance low-pass filter is placed in a transmission cavity 2 composed of an upper transmission component 2 and a lower transmission component 2; The quartz-based RF circuit board and the DC power supply expansion board are gold-plated on the front side, and 10 microns thick conductive silver glue is applied on the back side to be fixed to the metal lower base, wherein the DC power supply expansion board is placed on the lower bearing component 1 of the metal lower base; The MUTC-PD is fixed on the lower bearing table of the metal lower base by UV glue, and the upper surface of the MUTC-PD is flush with the upper surface of the quartz-based radio frequency circuit board. The single-mode optical fiber collimator is fixed in the lower bearing component 2 of the metal lower base by UV glue; The microlens is fixed on the lower bearing component 3 of the metal lower base by UV glue; The SMA coaxial interface is inserted into the lower bearing component 4 of the metal lower base and fixed with screws.

10. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package as claimed in claim 2, characterized in that: The MUTC-PD is bonded to the GCPW input transmission line with gold wire, the quartz-based RF circuit board is connected to the DC power supply expansion board with conductive silver glue, and the DC power supply expansion board and the SMA coaxial interface are connected with conductive silver glue.

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