Millimeter wave / terahertz emitter structure based on detector and Fabry-Perot resonant antenna
By integrating the detector with the Fabry-Perot resonant antenna to form a Fabry-Perot resonant cavity antenna, the problems of low gain and substrate leakage in photodetector integrated antennas are solved, achieving high-gain, high-directivity electromagnetic wave radiation output, which is suitable for highly integrated terahertz transmitters.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-17
- Publication Date
- 2026-04-03
AI Technical Summary
In existing technologies, the integration of photodetectors and patch antennas suffers from low gain and substrate leakage, resulting in low electromagnetic wave radiation efficiency and making it difficult to achieve high-power, highly integrated on-chip terahertz transmitters.
By employing a Fabry-Perot resonant cavity structure, the detector and Fabry-Perot resonant antenna are integrated to form a high-gain Fabry-Perot resonant cavity antenna. Through multiple reflections, electromagnetic waves are superimposed in phase, thereby improving radiation intensity and directivity.
It significantly improves the radiation intensity and gain in the main beam direction, achieves efficient electromagnetic wave radiation output, and has a highly integrated and high-power terahertz transmitter structure.
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Figure CN121790884A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of detector and antenna monolithic integration and Fabry-Perot resonant antenna technology, and particularly to a millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna. Background Technology
[0002] In terahertz (THz) applications, photodiodes (PDs) can generate microwave signals based on optical mixing effects, and are considered an effective solution for realizing tunable, low-phase-noise terahertz signal sources. To efficiently radiate the generated microwave signals into free space, a suitable output structure is needed to achieve effective coupling and radiation of electromagnetic energy. Currently, there are two main implementation paths: First, the PD is packaged as a rectangular waveguide or coaxial output module and connected to a horn antenna through a rectangular waveguide interface or coaxial interface to achieve high-efficiency microwave signal radiation; second, the PD is integrated with a patch antenna to achieve free-space radiation output over a wide bandwidth. Compared with waveguide / coaxial output modules, integrating a patch antenna on the PD can effectively eliminate high-frequency transmission losses and parasitic effects caused by bonding wires. Its radiation characteristics are not limited by the size of the rectangular waveguide or coaxial interface, thus significantly improving the system's bandwidth and radiation efficiency. Furthermore, this solution is compact, easy to integrate, and has the potential for arraying and large-scale integration.
[0003] Integrating a photodiode (PD) directly with a patch antenna enables seamless optical-to-RF signal conversion on a single chip, creating a compact terahertz signal source. However, using a PD monolithically integrated patch antenna as a terahertz signal source faces several challenges: First, the output power of the PD is typically limited by the device's bandwidth and saturation characteristics, restricting the output microwave signal power. Second, the high dielectric constant substrate of the PD can cause severe electromagnetic leakage. Typical III-V materials have high dielectric constants (ε_r≈12–13), which easily lead to electromagnetic energy coupling into the substrate at terahertz frequencies, resulting in reduced radiation efficiency, decreased radiation directivity, reduced gain, and main lobe distortion in the patch antenna. These issues become significant bottlenecks limiting the performance improvement of on-chip terahertz antennas. Summary of the Invention
[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, one objective of this invention is to propose a millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna, which features high integration, low profile, and can significantly improve the radiation intensity in the main beam direction, achieving high-gain, high-directivity radiation output.
[0005] The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to an embodiment of the present invention includes: A Fabry-Perot resonant cavity includes a metal cavity ground plane and a partial transmission dielectric plate. The partial transmission dielectric plate covers one side of the metal cavity ground plane, and a Fabry-Perot resonant cavity is formed between the partial transmission dielectric plate and the metal cavity ground plane. A PD monolithically integrated broadband patch antenna chip, the chip serving as a feed source and disposed in the Fabry-Perot resonant cavity, the PD being fixed to the metal cavity ground plane, and the broadband patch antenna facing the partial transmission dielectric plate.
[0006] The working principle of the millimeter-wave / terahertz transmitter structure based on the detector and Fabry-Perot resonant antenna in this invention embodiment is as follows: The PD generates microwave signals, such as millimeter-wave / terahertz signals, through optical mixing. The microwave signals are directly fed into the broadband patch antenna, which radiates the input microwave signals. When the electromagnetic wave propagates to the partial transmission dielectric plate, the partial transmission dielectric plate transmits a portion of the electromagnetic wave energy (such as a small portion) and reflects another portion of the electromagnetic wave energy (such as the majority). The reflected electromagnetic wave propagates in the Fabry-Perot resonant cavity to the metal cavity ground plane, where the metal cavity ground plane performs total reflection. This process repeats, and the electromagnetic wave propagates back and forth multiple times within the Fabry-Perot resonant cavity. Since the cavity height of the Fabry-Perot resonant cavity satisfies the Fabry-Perot resonance condition, the phases of the reflected electromagnetic waves are coherent. The electromagnetic waves transmitted from the partial transmission dielectric plate will have a phase superposition effect, thus increasing the antenna gain.
[0007] Compared with existing technologies, the millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna in this invention has the following advantages: By using a PD monolithically integrated broadband patch antenna chip as a feed source, placed in a Fabry-Perot resonant cavity between a grounded metal plate and a partially transmissive dielectric plate, a high-gain Fabry-Perot resonant cavity antenna is formed. Through the in-phase superposition effect of multiple reflections of electromagnetic waves by the Fabry-Perot resonant cavity, the radiation intensity in the main beam direction can be significantly improved, achieving high-gain and high-directivity radiation output. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna in this invention effectively compensates for the low gain and substrate leakage of existing PD monolithically integrated patch antennas, possessing excellent electromagnetic wave radiation efficiency, and providing a feasible and efficient way to realize a high-power, highly integrated on-chip terahertz transmitter.
[0008] In some embodiments, the partial transmission medium plate is an alumina plate, a silicon nitride plate, or a quartz plate.
[0009] In some embodiments, a recess is provided on one side of the metal cavity ground plane, and the partial transmission medium plate covers the opening of the recess, thereby forming a Fabry-Perot resonant cavity between the partial transmission medium plate and the metal cavity ground plane.
[0010] In some embodiments, the magnitude of the resonant enhancement frequency is changed by controlling the cavity height of the Fabry-Perot resonator.
[0011] In some embodiments, the broadband patch antenna includes a broadband patch antenna body, a positive electrode, and a negative electrode. The positive electrode is connected to the broadband patch antenna body via a positive wire, and the negative electrode is connected to the broadband patch antenna body via a negative wire. The broadband patch antenna body, the positive wire, the positive electrode, the negative wire, and the negative electrode are all integrated on the surface of the PD to form the chip.
[0012] In some embodiments, the broadband patch antenna body is a rectangular patch antenna, a butterfly antenna, a dipole resonant antenna, or a log-periodic dipole antenna.
[0013] In some embodiments, the butterfly patch antenna adopts a symmetrical double-arm structure.
[0014] In some embodiments, the PD achieves high-speed photoelectric conversion by optimizing the thickness of the absorption layer and the thickness of the drift region.
[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of a millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the PD monolithic integrated broadband patch antenna chip in an embodiment of the present invention; Figure 3 This is a gain curve of a Fabry-Perot resonant antenna based on a millimeter-wave / terahertz transmitter structure with a detector and a Fabry-Perot resonant antenna, according to an embodiment of the present invention.
[0017] Figure label: Fabry-Perot resonant cavity 1; metal cavity ground plane 101; partial transmission dielectric plate 102; Fabry-Perot resonant cavity 103; chip 2; PD 201; broadband patch antenna 202; broadband patch antenna body 2021; positive electrode 2022; positive line 2023; negative electrode 2024; negative line 2025. Detailed Implementation
[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0019] The following is combined with Figures 1 to 3 This invention describes a millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna, according to an embodiment of the present invention.
[0020] like Figures 1 to 3 As shown, the millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to an embodiment of the present invention includes a Fabry-Perot resonant cavity 1 and a chip 2 of a PD201 monolithically integrated broadband patch antenna 202.
[0021] The Fabry-Perot resonant cavity 1 includes a metal cavity ground plane 101 and a partial transmission dielectric plate 102. The partial transmission dielectric plate 102 covers one side of the metal cavity ground plane 101, forming a Fabry-Perot resonant cavity 103 between the partial transmission dielectric plate 102 and the metal cavity ground plane 101. The Fabry-Perot resonant cavity 103 means that its cavity height dimension satisfies the Fabry-Perot resonance condition. The chip 2 serves as a feed source and is disposed in the Fabry-Perot resonant cavity 103. The PD 201 is fixed on the metal cavity ground plane 101, and the broadband patch antenna 202 faces the partial transmission dielectric plate 102.
[0022] The working principle of the millimeter-wave / terahertz transmitter structure based on the detector and Fabry-Perot resonant antenna in this embodiment of the invention is as follows: PD201 generates microwave signals, such as millimeter-wave / terahertz signals, through optical mixing. The microwave signals are directly fed into the broadband patch antenna 202, which radiates the microwave signals to the partial transmission dielectric plate 102. When the electromagnetic wave reaches the partial transmission dielectric plate 102, the plate transmits a portion of the electromagnetic wave energy (a small portion) and reflects a larger portion (most of the electromagnetic wave energy). The reflected electromagnetic wave propagates in the Fabry-Perot resonant cavity 103 to the metal cavity ground plane 101, where it undergoes total internal reflection. This process repeats, and the electromagnetic wave propagates back and forth multiple times within the Fabry-Perot resonant cavity 103. Since the cavity height of the Fabry-Perot resonant cavity 103 satisfies the Fabry-Perot resonance condition, the phases of the reflected electromagnetic waves are coherent. The electromagnetic waves transmitted from the partial transmission dielectric plate 102 will have a phase superposition effect, thus increasing the antenna gain.
[0023] Compared with existing technologies, the millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna in this embodiment of the invention has the following advantages: By using the chip 2 of the PD201 monolithically integrated broadband patch antenna 202 as a feed source, placed in the Fabry-Perot resonant cavity 103 between the grounded metal plate 101 and part of the transmission dielectric plate 102, a high-gain Fabry-Perot resonant cavity 103 type antenna is formed. Through the in-phase superposition effect of multiple reflections of electromagnetic waves by the Fabry-Perot resonant cavity 1, the radiation intensity in the main beam direction can be significantly improved, achieving high-gain and high-directivity radiation output. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna in this embodiment of the invention effectively compensates for the low gain and substrate leakage of the existing PD monolithically integrated patch antenna, possessing excellent electromagnetic wave radiation efficiency, and providing a feasible and efficient way to realize a high-power, highly integrated on-chip terahertz transmitter.
[0024] In some embodiments, a portion of the transmission dielectric plate 102 is an alumina plate, a silicon nitride plate, or a quartz plate. Alumina and silicon nitride plates have high dielectric constants, resulting in lower transmission energy, higher gain, and lower bandwidth. Compared to alumina and silicon nitride plates, quartz plates have relatively lower dielectric constants, relatively lower gain, and relatively higher bandwidth.
[0025] The transmissive dielectric plate 102 can also be a dielectric plate made of other materials.
[0026] In some embodiments, a recess is provided on one side of the metal cavity ground plane 101, and a portion of the transmission dielectric plate 102 covers the opening of the recess, thereby forming a Fabry-Perot resonant cavity 103 between the portion of the transmission dielectric plate 102 and the metal cavity ground plane 101. The Fabry-Perot resonant cavity 1 has a simple structure and is easy to manufacture.
[0027] In some embodiments, the frequency of resonance enhancement is changed by controlling the cavity height of the Fabry-Perot resonator 103. Specifically, the resonance characteristics of the Fabry-Perot resonator 1 are adjusted by controlling the cavity height of the Fabry-Perot resonator 103, i.e., the distance between the partial transmission dielectric plate 102 and the metal cavity ground plane 101, thereby changing the frequency of resonance enhancement.
[0028] In some embodiments, the broadband patch antenna 202 includes a broadband patch antenna body 2021, a positive electrode 2022, and a negative electrode 2024. The positive electrode 2022 is connected to the broadband patch antenna body 2021 via a positive wire 2023, and the negative electrode 2024 is connected to the broadband patch antenna body 2021 via a negative wire 2025. The broadband patch antenna body 2021, the positive wire 2023, the positive electrode 2022, the negative wire 2025, and the negative electrode 2024 are all integrated on the surface of the PD201 to form the chip 2.
[0029] By integrating the broadband patch antenna body 2021, positive wire 2023, positive electrode 2022, negative wire 2025, and negative electrode 2024 onto the platform of PD201, the parasitic effects of leads and packaging can be eliminated. This is because in traditional heterogeneous integration of PD and external antenna, the PD output is usually connected to the antenna via gold wire bonding, and the leads introduce parasitic effects. On the other hand, the signal path length can be reduced, and the RF power transmission efficiency can be improved. This is because monolithic integration allows the photocurrent to be directly injected into the antenna without the need for external transmission line losses. Furthermore, the compact structure of chip 2 allows multiple PD-antenna units to be fabricated on the same substrate, facilitating the implementation of integrated arrays.
[0030] In some embodiments, the broadband patch antenna body 2021 is a rectangular patch antenna, a butterfly antenna, a dipole resonant antenna, or a log-periodic dipole antenna. The broadband patch antenna body 2021 has a simple structure and is easy to integrate with the PD201 monolithically. The appropriate structure can be selected according to the target frequency bandwidth and radiation characteristics requirements to balance bandwidth and gain. Rectangular patch antennas have the advantages of good directivity and easy impedance matching, making them suitable for narrowband high-gain applications; butterfly antennas have broadband characteristics; and dipole antennas have the simplest structure, facilitating integrated design with PD electrodes and enabling narrowband high-efficiency radiation.
[0031] The broadband patch antenna body 2021 can also be used for other antennas.
[0032] In some embodiments, the butterfly patch antenna employs a symmetrical double-arm structure. The butterfly patch antenna has a uniform electric field distribution and stable radiation characteristics. The symmetrical structure ensures that the current distribution generated by the two arms is symmetrical. The main lobe of the radiation direction is stable, resulting in better directivity and higher beam symmetry. The output is a linearly polarized field, avoiding polarization distortion.
[0033] In some embodiments, PD201 achieves high-speed photoelectric conversion by optimizing the thickness of the absorption layer and the thickness of the drift region.
[0034] like Figures 1 to 3 As shown below, a specific example of a millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to an embodiment of the present invention is given.
[0035] The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna in this embodiment of the invention mainly consists of three parts: a detector monolithically integrated broadband patch antenna 202, a metal cavity ground plane 101, and a partial transmission dielectric plate 102.
[0036] The PD201 employs an InP-based single-row carrier detector structure, achieving high-speed photoelectric conversion through optimized absorption layer thickness (250 nm) and drift region thickness (300 nm). It utilizes a waveguide-type single-row carrier detector based on an InP substrate with a thickness of 200 μm, and an active region size of 4 × 5 μm. 2 The broadband patch antenna body 2021 adopts a butterfly antenna. The butterfly patch antenna body adopts a symmetrical double-arm structure. Each arm is about 300µm long and about 400µm wide. The positive electrode 2022 and the negative electrode 2024 are connected to the two arms of the butterfly antenna through the positive line 2023 and the negative line 2025, respectively.
[0037] The Fabry-Perot resonant cavity 103, located between the metal cavity ground plane 101 and the partially transmissive dielectric plate 102, has a length and width of 9 mm and a height of 1.5 mm. The partially transmissive dielectric plate 102 is made of alumina and has a thickness of 300 µm. This structure satisfies the Fabry-Perot resonance condition near 100 GHz, achieving in-phase superposition of the emitted waves and significantly enhancing the electric field intensity in the main radiation direction. Electromagnetic simulation results are as follows: Figure 3 As shown, it maintains high directional radiation in the 90-106 GHz range, with a gain stable above 10 dBi, reaching a maximum of about 17 dBi near 100 GHz.
[0038] It should be noted that monolithic integration, as mentioned above, refers to integrating multiple devices or functional modules on the same substrate.
[0039] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna, characterized in that, include: A Fabry-Perot resonant cavity includes a metal cavity ground plane and a partial transmission dielectric plate. The partial transmission dielectric plate covers one side of the metal cavity ground plane, and a Fabry-Perot resonant cavity is formed between the partial transmission dielectric plate and the metal cavity ground plane. A PD monolithically integrated broadband patch antenna chip, the chip serving as a feed source and disposed in the Fabry-Perot resonant cavity, the PD being fixed to the metal cavity ground plane, and the broadband patch antenna facing the partial transmission dielectric plate.
2. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to claim 1, characterized in that, The transmission medium plate is an alumina plate, a silicon nitride plate, or a quartz plate.
3. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to claim 1, characterized in that, A recess is provided on one side of the metal cavity ground plane, and the partial transmission medium plate covers the opening of the recess, thereby forming a Fabry-Perot resonant cavity between the partial transmission medium plate and the metal cavity ground plane.
4. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to claim 1, characterized in that, The frequency of resonance enhancement can be changed by controlling the cavity height of the Fabry-Perot resonator.
5. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to claim 1, characterized in that, The broadband patch antenna includes a broadband patch antenna body, a positive electrode, and a negative electrode. The positive electrode is connected to the broadband patch antenna body via a positive wire, and the negative electrode is connected to the broadband patch antenna body via a negative wire. The broadband patch antenna body, the positive wire, the positive electrode, the negative wire, and the negative electrode are all integrated on the surface of the PD to form the chip.
6. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to claim 5, characterized in that, The broadband patch antenna body can be a rectangular patch antenna, a butterfly antenna, a log-periodic antenna, or a dipole resonant antenna.
7. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to claim 6, characterized in that, The butterfly patch antenna adopts a symmetrical double-arm structure.
8. The millimeter-wave / terahertz transmitter structure based on a detector and a Fabry-Perot resonant antenna according to claim 1, characterized in that, The PD achieves high-speed photoelectric conversion by optimizing the thickness of the absorption layer and the drift region.