G-band terahertz photomixing module based on WR5.1 metal waveguide package

Abstract

The application provides a G-band terahertz photomixing module based on a WR5.1 metal waveguide package, characterized in that the module comprises a WR5.1 waveguide cavity structure composed of an upper metal 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, the WR5.1 waveguide cavity structure is further provided with a MUTC-PD, a quartz-based radio frequency circuit board and a direct current power supply extension board; the direct current power supply extension 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 a lens focal point of the microlens is on a waveguide cleavage surface of the MUTC-PD. The technical scheme disclosed by the application can solve the problems of low radio frequency circuit integration, large transmission link loss and high processing difficulty in the prior art, and realize high-power terahertz signal output.

Description

TECHNICAL FIELD

[0001] The application relates to a G-band terahertz photomixing module based on a WR5.1 metal waveguide package, and belongs to the technical field of MUTC-PD terahertz emission modules. BACKGROUND

[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 terahertz signal generation methods mainly include electrical and optical methods. The electrical method includes signal generation methods based on frequency multiplication and mixing technology, but this method usually has defects such as narrow frequency band, multiple harmonics and low transmission rate. In contrast, the modified unipolar carrier transport photodetector (MUTC-PD) uses optical heterodyne beat frequency technology to generate terahertz signals, which has the advantages of wide bandwidth, no harmonics and high transmission rate. Therefore, the optical generation of terahertz sources has become an important development direction in terahertz technology.

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

[0004] In existing MUTC-PD waveguide packaging modules, a branch bias method is usually used to provide direct current power supply and radio frequency current suppression. However, as the frequency increases (for example, G-band: 140GHz-220GHz), the radio frequency circuit needs to use low dielectric constant materials (such as quartz) and reduce the size to reduce the loss. The three design methods of the branch bias method will increase the radio frequency loss or the processing and assembly difficulty to some 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 radio frequency loss. By drilling holes in the board, the radio frequency loss can be reduced, but the processing difficulty and cost are undoubtedly increased.

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

[0007] 3. Print the branch and radio frequency main path respectively and then bond them together, which will increase the radio frequency loss and assembly difficulty.

[0008] The short end backshort design of the waveguide assembly is also unreasonable, which can cause the loss of high frequency signals to increase, and affect the system bandwidth performance, and this is usually not considered in the traditional module design.

[0009] The existing and traditional excitation probe is generally rectangular in shape, and the structure of the excitation probe is not explored, so that the working bandwidth is limited. SUMMARY

[0010] The purpose of the present application is to solve the problems of low output power of the existing G-band optical terahertz source by comprehensively considering impedance matching, high integration and low loss in the design of the transmission link.

[0011] In order to achieve the above purpose, the technical scheme of the present application discloses a G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide packaging, characterized in that it comprises 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 micro-lens located in the WR5.1 waveguide cavity structure form an optical focusing system, and the WR5.1 waveguide cavity structure is further provided with a MUTC-PD, a quartz-based radio frequency circuit board and a direct current power supply expansion board; the direct current 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 focal point of the micro-lens is on the waveguide cleavage surface of the MUTC-PD.

[0012] Preferably, the quartz-based radio frequency circuit board comprises a characteristic impedance matched GCPW input transmission line, 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 direct current bias voltage for the MUTC-PD and suppress radio frequency signal leakage.

[0016] Preferably, the quartz-based radio frequency circuit board takes 50 microns thick quartz as the 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 on a straight line along the quartz-based radio frequency circuit board.

[0018] Preferably, the characteristic impedance of the 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 a width of 280 microns and 20 microns.

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

[0021] Preferably, the output waveguide interface is composed of the upper waveguide assembly of the upper metal base and the lower waveguide assembly of the lower metal base, and the waveguide interface is in the form of WR5.1, covering the frequency range of 140 GHz to 220 GHz; the short ends of the upper waveguide assembly and the lower waveguide assembly are treated with a 320-micron chamfer to reduce high-frequency return loss, and the far ends are standard WR5.1 waveguide output ports.

[0022] Preferably, the two sides of the upper waveguide assembly of the upper metal base are the upper transmission assembly one and the upper transmission assembly two, and the two sides of the lower waveguide assembly of the lower metal base are the lower transmission assembly one and the lower transmission assembly two.

[0023] The GCPW input transmission line with matched characteristic impedance is placed in the transmission cavity one composed of the upper transmission assembly one and the lower transmission assembly one, and the ground of the lower metal base and the GCPW input transmission line is connected to form a common ground through conductive silver paste.

[0024] The on-chip integrated stepped impedance low-pass filter is placed in the transmission cavity two composed of the upper transmission assembly two and the lower transmission assembly two.

[0025] The quartz-based RF circuit board and the DC power supply extension board are gold-plated on the front surface and coated with 10-micron-thick conductive silver paste on the back surface and fixed to the lower metal base, wherein the DC power supply extension board is placed on the lower bearing assembly one of the lower metal base.

[0026] The MUTC-PD is fixed to the lower bearing platform of the lower metal base with UV glue, and the upper surface of the MUTC-PD is flush with the upper surface of the quartz-based RF circuit board.

[0027] The single-mode fiber collimator is fixed to the lower bearing assembly two of the lower metal base with UV glue.

[0028] The microlens is fixed to the lower bearing assembly three of the lower metal base with UV glue.

[0029] The SMA coaxial interface is inserted into the lower bearing assembly four of the lower metal base and fixed with a screw.

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

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

[0032] Same-direction linear bias circuit integration design: Unlike the traditional branch bias scheme, the application adopts the same-direction linear layout design of the characteristic impedance matched GCPW input transmission line, the improved ultra-wideband fan-shaped excitation probe and the on-chip integrated stepped impedance low-pass filter. This design significantly solves the problems of low integration of the radio frequency circuit and large transmission link loss.

[0033] Waveguide backshort optimization design: By improving the backshort structure of the waveguide, 320 microns of chamfering are processed, which effectively reduces the return loss at high frequency and improves the bandwidth characteristics of the system.

[0034] The metal lower base and the ground wire of the GCPW input transmission line are connected by conductive silver glue to form a common ground, which eliminates the process step of punching a hole on the chip, greatly reduces the processing difficulty, and also achieves the effect of low-loss transmission.

[0035] The geometry of the excitation probe is designed and optimized, and an improved ultra-wideband fan-shaped excitation probe is 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 DRAWINGS

[0036] Figure 1 It is a schematic diagram of the appearance structure of the G-band terahertz photomixer module based on WR5.1 metal waveguide packaging.

[0037] Figure 2 It is a schematic diagram of the internal design structure of the cavity.

[0038] Figure 3 It is a schematic diagram of the internal structure of the metal lower base.

[0039] Figure 4 It is a schematic diagram of the internal structure of the metal upper base.

[0040] Figure 5 The MUTC-PD, the quartz-based radio frequency circuit and the DC power supply extension board are illustrated. DETAILED DESCRIPTION

[0041] The application will be further described in connection with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that after reading the content of the application, those skilled in the art can make various modifications or changes to the application, and these equivalent forms also fall within the scope defined by the appended claims.

[0042] As shown in Figs. 1, 2, 3, 4, the G-band terahertz photomixing module based on WR5.1 metal waveguide package disclosed in the embodiment comprises a WR5.1 waveguide cavity structure composed of a metal upper base 1 and a metal lower base 2, an optical focusing system composed of an SMA coaxial interface 3, a single-mode fiber collimator 4 and a micro-lens 5, a MUTC-PD 6, a quartz-based radio frequency circuit board 7 placed in the metal lower base 2 and a direct current power supply extension board 8. Figure 1 , 2

[0043] As shown in Figs. 1, 2, 3, 4, the waveguide cavity structure is composed of the metal upper base 1 and the metal lower base 2. The back short 206 of the waveguide assembly is processed by 320-micron chamfering for reducing 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 in other embodiments, aluminum can be selected, which is first precisely milled by a precision machine tool, and then surface plated to obtain. Figure 1 , 3

[0044] As shown in Figs. 1, 2, 3, 4, the waveguide assembly 101 of the metal upper base 1 cooperates with the waveguide assembly 201 of the metal lower base 2 to form an output waveguide interface, which is in the form of WR5.1 and covers the frequency band of 140GHz-220GHz. Figure 3 4 As shown in Figs. 1, 2, 3, 4, the waveguide assembly 101 of the metal upper base 1 cooperates with the waveguide assembly 201 of the metal lower base 2 to form an output waveguide interface, which is in the form of WR5.1 and covers the frequency band of 140GHz-220GHz.

[0045] As shown in Figs. 1, 2, 3, 4, the quartz-based radio frequency circuit board 7 takes 50-micron-thick quartz as a carrier board, and comprises a characteristic impedance matched GCPW input transmission line 701 (with a characteristic impedance of 50 ohms), an improved ultra-wideband sector excitation probe 702 and an on-chip integrated stepped impedance low-pass filter 703, which are distributed in a straight line along the quartz-based radio frequency 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 sector excitation probe 702 is used to excite the TE10 waveguide of the WR5.1 waveguide. The on-chip integrated stepped impedance low-pass filter 703 is used to provide a direct current bias voltage for the MUTC-PD 6 and suppress radio frequency signal leakage, and is composed of periodically arranged microstrip lines with a width of 280 microns and 20 microns. Figure 5

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

[0047] like Figure 2 、 3 As shown in Figures 4 and 5, the quartz-based RF circuit board 7 and DC power supply expansion board 8 are gold-plated on the front and coated with 10-micron-thick conductive silver glue on the back, securely mounted to the metal lower base 2. A characteristic impedance-matched GCPW input transmission line 701 is placed in the transmission cavity formed by the transmission component 103 of the metal upper base 1 and the transmission component 205 of the metal lower base 2. The ground lines of the metal lower base 2 and the GCPW input transmission line 701 are connected via conductive silver glue to form a common ground. An on-chip stepped impedance low-pass filter 703 is placed in the transmission cavity formed by 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 support component 208 of the metal lower base 2. The MUTC-PD 6 is secured to the support platform 204 of the metal lower base 2 using UV glue, with the top surface of the MUTC-PD 6 flush with the top surface of the quartz-based RF circuit board 7.

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

Claims

1. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package, characterized in that: The WR5.1 waveguide cavity structure comprises a WR5.1 waveguide cavity structure consisting 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 at the other end of the WR5.1 waveguide cavity structure. The single-mode fiber collimator and a microlens located within the WR5.1 waveguide cavity structure form an optical focusing system. The WR5.1 waveguide cavity structure also houses a MUTC-PD, a quartz-based RF circuit board, and a DC power supply expansion board. 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. The microlens has a focal point on the waveguide cleavage plane of the MUTC-PD. The quartz-based RF circuit board includes a GCPW input transmission line with characteristic impedance matching, an improved ultra-wideband sector-shaped excitation probe, and an on-chip integrated stepped impedance low-pass filter, wherein: A GCPW input transmission line with characteristic impedance matching is used to connect the MUTC-PD as a signal input terminal; An improved ultra-wideband sector-shaped excitation probe is used to excite the TE10 waveguide of the WR5.1 waveguide; An 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; The DC power supply expansion board uses 150 micron thick quartz as a carrier board, on which connection metal pads are printed for connecting to the on-chip integrated stepped impedance low-pass filter and the SMA coaxial interface; The upper waveguide component of the metal upper base is flanked by an upper transmission component 1 and an upper transmission component 2, and the lower waveguide component of the metal lower base is flanked by a lower transmission component 1 and a lower transmission component 2; 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 second transmission cavity composed of a second upper transmission component and a second lower transmission component; The quartz-based RF circuit board and the DC power supply expansion board are gold-plated on the front and coated with 10-micron-thick conductive silver glue on the back and fixed to the metal lower base, wherein the DC power supply expansion board is placed on the lower supporting component 1 of the metal lower base.

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

3. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide packaging according to claim 1, 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.

4. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide packaging according to claim 1, characterized in that: The characteristic impedance of the characteristic impedance-matched GCPW input transmission line is 50 ohms.

5. The G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide package according to claim 1, 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.

6. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide packaging according to claim 5, 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 and lower waveguide components are chamfered by 320 microns to reduce high-frequency return loss, and the far end is a standard WR5.1 waveguide output port.

7. A G-band terahertz optoelectronic mixing module based on WR5.1 metal waveguide packaging according to claim 6, characterized in that: The MUTC-PD is fixed to the lower bearing surface of the metal lower base with UV glue, and the upper surface of the MUTC-PD is flush with the upper surface of the quartz-based RF circuit board; The single-mode optical fiber collimator is fixed to 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.

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

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