A dual antenna photonic transmitter based on a traveling wave detector

Abstract

The application discloses a dual-antenna photonic transmitter based on a traveling wave detector, which comprises two antennas and a traveling wave photodetector, wherein the two antennas are respectively arranged at the terminals of the traveling wave photodetector. The traveling wave photodetector used by the dual-antenna photonic transmitter removes the 50-ohm resistor at the input end of the traditional traveling wave electrode, thereby reducing the shunt loss of the resistor. In addition, the antenna matched with the impedance of the traveling wave photodetector is introduced at the input terminal of the traveling wave photodetector, thereby eliminating the RF signal reflection caused by the removal of the matching resistor and improving the bandwidth of the traveling wave photodetector. The dual-antenna photonic transmitter structure with one traveling wave photodetector integrated with two antennas not only effectively improves the radiation power of the photonic transmitter, but also has compact structure and good consistency, and is conducive to forming a large-scale photonic transmitter array.

Description

Technical Field

[0001] This invention relates to the field of integrated optoelectronic device technology, and in particular to a dual-antenna photonic emitter based on a traveling wave detector. Background Technology

[0002] With the ever-increasing global demand for high-speed data transmission rates, next-generation communication networks are placing increasingly higher demands on device bandwidth. In high-speed links, purely electronic systems have inherent drawbacks, such as high cable loss, narrow electronic device bandwidth, and incompatibility between different frequency bands. Therefore, compared to purely electronic solutions, photonic transmitters developed using photonic technology to generate millimeter-wave wireless communication offer significant advantages. They feature low fiber loss, high device bandwidth, and strong resistance to electromagnetic interference, and can completely replace the tens of thousands of expensive coaxial cable antenna coverage systems used in modern wireless networks, while also increasing scalability.

[0003] Current conventional photonic transmitter designs integrate a single antenna with a photodetector, but their relatively weak radiated power limits long-range wireless transmission in wireless network systems. In 2019, Ali Hajimiri's research group proposed a fully integrated broadband tunable silicon-based photonic transmitter. Its detector unit uses a dual-input germanium-silicon photodetector, and the single antenna unit employs a highly directional Vivaldi antenna. This photonic transmitter system achieved a detector bandwidth of 32 GHz. However, due to the low RF saturation power of the detector and the fact that a single detector is integrated with only a single antenna unit, its effective radiated power only reaches -65 dBm at 44 GHz. Therefore, achieving a low-loss, high-radiated-power photonic transmitter remains an important challenge. Summary of the Invention

[0004] The purpose of this invention is to design a dual-antenna photon transmitter based on a traveling wave detector to reduce the additional power consumption at the matching impedance end of the traveling wave photodetector and achieve high radiation power of the photon transmitter.

[0005] To achieve the above design goals, the technical solution of the present invention is as follows:

[0006] A dual-antenna photonic transmitter based on a traveling-wave detector is disclosed. The dual-antenna photonic transmitter includes two antennas and a traveling-wave photodetector. The two antennas are located at opposite ends of the traveling-wave photodetector. The two antennas are impedance-matched to the traveling-wave photodetector. The input end of the traveling-wave photodetector uses an impedance-matched antenna instead of a traditional 50-ohm resistor, reducing the shunt loss of the resistor. The introduction of an impedance-matched antenna at the input end of the traveling-wave photodetector not only eliminates RF signal reflection caused by removing the matching resistor and improves the bandwidth of the traveling-wave photodetector, but also effectively increases the radiation power of the photonic transmitter.

[0007] Furthermore, in the above technical solution, the antenna can be any one of a Yagi antenna, a Vivaldi antenna, or a helical antenna.

[0008] Furthermore, the Yagi antenna includes an excitation element, a director, and a reflector, with the reflector also serving as a ground plane.

[0009] Furthermore, the traveling wave photodetector is made of any one of silicon-on-insulator (SOI), gallium arsenide, or indium phosphide.

[0010] Furthermore, the antenna and traveling-wave photodetector can be integrated using either hybrid integration or monolithic integration. When hybrid integration is chosen, the antenna is made of a PCB board, and the antenna and traveling-wave photodetector can be integrated together using flip-chip packaging or wire bonding. When monolithic integration is chosen, the antenna and traveling-wave photodetector are made of the same material.

[0011] Furthermore, the traveling-wave photodetector is an n-level distributed traveling-wave detector, specifically comprising n detector units, log₂n multimode interferometers (MMIs), one fiber coupler, and one traveling-wave electrode. The detector units of this traveling-wave photodetector can be distributed in a periodic or aperiodic structure.

[0012] Furthermore, the traveling wave electrode of the traveling wave photodetector is a coplanar stripline CPS structure, thereby eliminating the need for a transition balun from the traveling wave photodetector to the antenna and reducing power loss.

[0013] Furthermore, the bias network can be an inductive metal wire or composed of multiple cascaded spiral inductors. This bias network has the characteristic of passing DC while blocking AC, providing DC bias for the traveling wave photodetector while suppressing the output of RF AC signals from the bias terminal, thereby improving the output power of the traveling wave photodetector.

[0014] Furthermore, the wavelength range of the input optical signal of the dual-antenna photonic transmitter can be at least one of the C-band or O-band.

[0015] Furthermore, the dual-antenna photonic emitter based on the traveling wave detector can form an i×j large-scale photonic emitter array.

[0016] The beneficial effects of this invention are as follows:

[0017] Compared to traditional photon transmitters, the dual-antenna photon transmitter of this invention employs a traveling-wave photodetector and eliminates the traditional 50-ohm resistor at its input terminal, reducing the additional power loss caused by photocurrent shunting to the 50-ohm resistor. Furthermore, an impedance-matched antenna is introduced at the input terminal, which not only eliminates the reflection of backpropagating RF signals at the traveling-wave electrode input terminal caused by resistor removal, improving the photodetector bandwidth, but also increases the efficiency of feeding the traveling-wave detector signal into the antenna system and radiating it into space, achieving high radiation power for the photon transmitter. The dual-antenna photon transmitter of this invention has a compact structure and good consistency, facilitating the construction of large-scale photon transmitter arrays. Attached Figure Description

[0018] Figure 1 This invention relates to a dual-antenna photon emitter based on a traveling wave detector;

[0019] Figure 2 It is a simulated three-dimensional gain pattern of the antenna;

[0020] Figure 3 This is a schematic diagram of a traveling wave photodetector.

[0021] Figure 4 This is a simulated frequency response diagram of a traveling wave photodetector;

[0022] In the diagram: 1. Antenna, 2. Traveling wave photodetector, 3. Bias network, 4. Pad, 5. Director, 6. Excitation oscillator, 7. Reflector, 8. Fiber optic coupler, 9. Multimode interferometer, 10. Detector unit, 11. Traveling wave electrode. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] like Figure 1This invention discloses a dual-antenna photonic transmitter based on a traveling-wave detector, comprising two antennas 1 and a traveling-wave photodetector 2. The invention integrates the two antennas onto the two ends of the traveling-wave electrode of the traveling-wave photodetector, replacing the 50-ohm resistor at the input of the traveling-wave photodetector with an impedance-matched antenna. This not only reduces the current shunt loss of the resistor and increases the radiation power of the photonic transmitter, but also eliminates RF signal reflection caused by removing the matching resistor, improving the bandwidth of the traveling-wave photodetector and achieving broadband high-power radiation of the photonic transmitter. The antennas 1 employ a Yagi antenna to improve antenna gain and directivity; the traveling-wave photodetector 2 employs an aperiodic loading type traveling-wave detector to improve both RF saturation power and detector bandwidth.

[0025] like Figure 1 As shown, the Yagi antenna 1 employs a coplanar stripline CPS feeding method. This coplanar stripline CPS has the same structure as the traveling wave electrode 11 of the traveling wave photodetector 2, which eliminates the need for the conversion transition balun required for mode conversion at the antenna feed end, thereby reducing the transmission loss of the RF signal from the traveling wave photodetector 2 to the antenna 1. The Yagi antenna 1 comprises three parts: a director 5, an excitation element 6, and a reflector 7. The reflector 7 also serves as a ground plane, significantly reducing the antenna size. The three-dimensional gain pattern of the Yagi antenna 1, simulated using the three-dimensional electromagnetic simulation software Ansys HFSS, is shown below. Figure 2 As shown, its gain is 3.6 dBi, achieving high-gain, highly directional radiation.

[0026] Figure 3This is a schematic diagram of the traveling-wave photodetector 2, which includes four parts: an optical fiber coupler 8, a multimode interferometer 9, detector units 10, and traveling-wave electrodes 11. The traveling-wave photodetector is an n-stage traveling-wave detector, integrating n detector units 10, which ensures uniform distribution of optical power and avoids current saturation of a single detector unit 10, thereby improving the RF saturation power of the traveling-wave detector 2. This invention employs a non-periodic loading type traveling-wave detector, where adjacent (n-1)th and nth detector units 10 have a certain spacing, and the spacing of the detector units 10 is optimized based on a genetic algorithm. The non-uniformity of the non-periodic loading type traveling-wave detector causes the optical current in the two propagation directions of the traveling-wave photodetector 2 to no longer be uniformly distributed, resulting in an imbalance between the amplitude of the forward RF signal and the amplitude of the reflected backward RF signal, weakening their interference intensity and thus alleviating the limitation of device bandwidth caused by their phase lag. To achieve speed matching, the output ports of the traveling-wave detector unit array 10 and the multimode interferometer 9 are connected through optical waveguide delay lines of different lengths, synchronizing the RF signals generated by different detector units 10 in the traveling-wave electrodes 11. By establishing an equivalent circuit model of detector unit 10 and traveling wave electrode 11, the frequency response characteristics of the RF signal output from traveling wave photodetector 2 to the load terminal of antenna 1 can be obtained according to the transfer matrix method, such as... Figure 4 As shown, the traveling wave photodetector has a 3dB bandwidth of up to 39GHz.

[0027] The dual-antenna photon emitter receives an external DC bias voltage via pad 4 using either probe bonding or gold wire bonding. This DC bias voltage then provides the reverse bias voltage required for the PN junction of the traveling-wave photodetector 2 through bias network 3. The bias network 3 is an inductive metal wire, functioning similarly to a bias network composed of spiral inductors. It has the characteristic of allowing DC while blocking AC, providing a DC operating voltage to the traveling-wave photodetector 2 while simultaneously preventing the RF signal generated by the traveling-wave photodetector 2 from transmitting to the bias network 3. This improves the efficiency of RF signal feeding to antenna 2 and further enhances the radiation power of the photon emitter.

[0028] When light is fed into the multimode interferometer 9 through the fiber optic coupler 8, the optical power is evenly distributed to the n detector units 10 and undergoes photoelectric conversion. The generated photocurrent is collected by the traveling wave electrode 11 and transmitted to the terminals on both sides of the traveling wave electrode 11, and then fed into the feed ports of the two antennas 1. Finally, the antennas 1 convert the RF electrical signal into an electromagnetic wave signal and radiate it into space. This process completes the optical-electrical-magnetic signal conversion, and because an antenna 1 is integrated on each side of the traveling wave photodetector 2, this dual-antenna photonic transmitter has advantages such as low loss, high gain, and high radiated power.

[0029] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-antenna photonic emitter based on a traveling-wave detector, characterized in that: It includes two antennas and a traveling wave photodetector; the two antennas are located at the two ends of the traveling wave photodetector respectively; the 50-ohm resistor at the input end of the traveling wave photodetector is reduced; the two antennas are impedance matched with the traveling wave photodetector.

2. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 1, characterized in that: The antenna can be any one of a Yagi antenna, a Vivaldi antenna, or a spiral antenna.

3. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 1, characterized in that: The traveling wave photodetector is made of any one of silicon-on-insulator (SOI), gallium arsenide, or indium phosphide.

4. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 1, characterized in that: The antenna and traveling wave photodetector are integrated through hybrid integration or monolithic integration.

5. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 4, characterized in that: When the antenna and traveling wave photodetector are integrated in a hybrid integration manner, the antenna is made of a PCB board; when the antenna and traveling wave photodetector are integrated in a monolithic integration manner, the antenna is made of the same material as the traveling wave photodetector.

6. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 1, characterized in that: The traveling wave photodetector is an n-level distributed traveling wave detector, specifically including n detector units, log₂n multimode interferometers, one fiber coupler, and one traveling wave electrode.

7. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 1, characterized in that: The traveling wave electrodes of the traveling wave photodetector are coplanar stripline CPS structures.

8. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 1, characterized in that: The dual-antenna photonic transmitter based on a traveling wave detector uses a bias network to provide a bias voltage. The bias network is an inductive metal wire or is composed of multiple cascaded spiral inductors.

9. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 1, characterized in that: The input light is either C-band or O-band.

10. The dual-antenna photonic emitter based on a traveling-wave detector according to claim 1, characterized in that: Used to construct the i×j photon emitter array.

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