Optical communication system

Abstract

The invention discloses an optical communication system, and relates to the technical field of optical communication, and the optical communication system comprises an optical transmitting module, an optical receiving module and an optical conduction module. The light emitting module comprises a light emitting part which is used for emitting light. The light receiving module comprises a photoelectric detector and a signal processor, the photoelectric detector is in communication connection with the signal processor, the photoelectric detector receives light rays emitted by the light emitting part and converts the light rays into analog signals, and the signal processor reads the analog signals generated by the photoelectric detector and outputs digital signals; the light conduction module is arranged between the light emitting module and the light receiving module and conducts light emitted by the light emitting part to the photoelectric detector. According to the optical interconnection technology, attenuation is low during data transmission, the optical interconnection technology is not prone to electromagnetic interference, and the anti-interference capability, the transmission rate and the transmission distance during signal transmission can be improved.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to an optical communication system. Background Technology

[0002] Currently, data exchange between chips and modules mainly relies on metal wires on printed circuit boards. However, with the explosive growth of system computing power, higher requirements are being placed on the transmission rate, anti-interference capability, and transmission distance of interconnect technologies.

[0003] Existing electrical interconnection technologies, limited by physical principles and technological bottlenecks, are unable to meet these demands. In particular, high-frequency signals suffer severe attenuation and are susceptible to electromagnetic interference on metal transmission lines, affecting signal integrity, limiting transmission rates and effective distances, and making it difficult to meet the ever-increasing demand for data exchange. Summary of the Invention

[0004] The main objective of this invention is to propose an optical communication system that addresses the problems of poor anti-interference capability, transmission rate, and transmission distance in existing electrical interconnection technologies.

[0005] To achieve the above objectives, the present invention proposes an optical communication system comprising an optical emitting module, an optical receiving module, a flexible circuit board, and an optical transmission module. The optical emitting module includes a light-emitting element for emitting light. The optical receiving module includes a photodetector and a signal processor, which are communicatively connected. The photodetector receives the light emitted by the light-emitting element and converts it into an analog signal. The signal processor reads the analog signal generated by the photodetector and outputs a digital signal. Both the optical receiving module and the optical emitting module are electrically connected to the flexible circuit board. The optical transmission module is located between the optical emitting module and the optical receiving module and transmits the light emitted by the light-emitting element to the photodetector.

[0006] In one embodiment of the present invention, the light transmission module includes a first lens, a second lens, and a light transmission element. The first lens is attached to the light-emitting side of the light-emitting element, the second lens is attached to the light-incident side of the photodetector, and the two ends of the light transmission element are connected to the first lens and the second lens. The light emitted by the light-emitting element is focused by the first lens onto the light-conducting element and then conducted to the second lens, which focuses the light onto the photodetector.

[0007] In one embodiment of the present invention, the optical transmission element is an optical fiber.

[0008] In one embodiment of the present invention, the light-emitting element is a Micro LED.

[0009] In one embodiment of the present invention, the light emitting module includes a plurality of Micro LEDs, the light receiving module includes a plurality of photodetectors, and the light transmitting module includes a plurality of optical fibers, each of which receives a light signal emitted by a Micro LED and transmits it to a photodetector.

[0010] In one embodiment of the present invention, the optical communication system includes a first chip, a second chip, a first flexible circuit board, and a second flexible circuit board; The first chip is packaged on the first flexible circuit board, and the second chip is packaged on the second flexible circuit board; multiple light-emitting elements are integrated on the first chip and electrically connected to the first flexible circuit board; multiple photodetectors are integrated on the second chip and electrically connected to the second flexible circuit board.

[0011] In one embodiment of the present invention, the optical communication system includes a first chip, a second chip, a first flexible circuit board, and a second flexible circuit board; The first chip is packaged on the first flexible circuit board, and the second chip is packaged on the second flexible circuit board; both the first chip and the second chip integrate the light-emitting element and the photodetector, and the light-emitting element and the photodetector integrated on the first chip are electrically connected to the first flexible circuit board; the light-emitting element and the photodetector integrated on the second chip are electrically connected to the second flexible circuit board.

[0012] In one embodiment of the present invention, the photodetector is a spin photodetector; And / or, the signal processor is a comparator.

[0013] In one embodiment of the present invention, the light emitting module further includes a driver, which is electrically connected to the light-emitting element.

[0014] In one embodiment of the present invention, the light emitting module further includes a first equalizer, which is electrically connected to the driver and the light-emitting element. The first equalizer is used to equalize and enhance the high-frequency driving signal generated by the driver. And / or, the optical receiving module further includes a second equalizer, which is electrically connected to the photodetector and the signal processor, and is used to equalize and enhance the high-frequency analog signal generated by the photodetector.

[0015] The optical communication system proposed in this invention includes an optical emitting module, an optical receiving module, and an optical transmission module. The optical emitting module includes a light-emitting element for emitting light. The optical receiving module includes a photodetector and a signal processor, with the photodetector and signal processor communicatively connected. The optical transmission module is positioned between the optical emitting and receiving modules, transmitting the light emitted by the light-emitting element to the photodetector. The photodetector receives the light emitted by the light-emitting element and converts it into an analog signal. The signal processor reads the analog signal generated by the photodetector and outputs a digital signal to achieve signal transmission. Compared to traditional interconnection technologies using metal wires, the optical interconnection technology of this application exhibits lower data attenuation and is less susceptible to electromagnetic interference during data transmission, thus improving anti-interference capability, transmission rate, and transmission distance. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the optical communication system provided by the present invention; Figure 2 A schematic diagram of the optical communication system provided by the present invention in another embodiment; Figure 3 A schematic diagram of an embodiment of the optical communication module provided by the present invention; Figure 4 This is a schematic diagram of the optical communication module provided by the present invention in another embodiment.

[0018] Explanation of icon numbers: 11. Light-emitting element; 12. Driver; 131. First flexible circuit board; 132. First chip; 14. First equalizer; 21. Photodetector; 211. First spin photodetector; 212. Second spin photodetector; 22. Signal processor; 23. Second equalizer; 241. Second flexible circuit board; 242. Second chip; 30. Light transmission module; 31. Light transmission element; 32. First lens; 33. Second lens; 40. Sealing layer.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] This invention proposes an optical communication system.

[0024] Combination Figures 1 to 3 As shown, in one embodiment of the present invention, the optical communication system includes an optical emitting module, an optical receiving module, and an optical transmission module 30; the optical emitting module includes a light-emitting element 11, which is used to emit light; the optical receiving module includes a photodetector 21 and a signal processor 22, which are communicatively connected. The photodetector 21 receives the light emitted by the light-emitting element 11 and converts it into an analog signal. The signal processor 22 reads the analog signal generated by the photodetector 21 and outputs a digital signal; the optical transmission module 30 is disposed between the optical emitting module and the optical receiving module and transmits the light emitted by the light-emitting element 11 to the photodetector 21.

[0025] In this embodiment, the optical emitting module serves as the signal source of the optical communication system, and the light-emitting element 11 is a semiconductor light-emitting device that can receive electrical signals and convert them into light signals of corresponding intensity for emission.

[0026] As the signal receiver in an optical communication system, the core function of the optical receiver module is to perform the "optical-to-electrical-to-digital" conversion. The optical receiver module includes a photodetector 21 and a signal processor 22. The photodetector 21 receives the optical signal from the optical transmitter module and converts it into an analog electrical signal (such as a changing voltage, current, or resistance). The signal processor 22 reads this analog signal and compares it with an internally or externally set reference threshold, thereby outputting a high-level or low-level digital signal. This direct-connection architecture of "detector-signal processor 22" eliminates the need for transimpedance amplifiers (TIAs) and multi-stage limiting amplifiers (LAs) in the associated optical receiver link, simplifying the analog front-end and reducing power consumption and noise.

[0027] The optical transmission module 30 connects the optical emitting module and the optical receiving module, positioned between them. It directs the light emitted from the light-emitting element 11 to the photosensitive surface of the photodetector 21 in a low-loss, high-fidelity manner. This waveguide-based optical interconnection method solves the problems of electromagnetic interference (EMI), crosstalk, and the rapidly increasing transmission line loss with increasing frequency present in traditional electrical interconnections. Through the coordinated operation of the optical emitting module, the optical transmission module 30, and the optical receiving module, the optical communication system achieves the conversion process from electrical signal to optical signal to electrical signal to digital signal, providing a high-bandwidth, low-latency, and interference-resistant data transmission channel between chips, boards, and even cabinets, effectively solving the problems of speed, distance, and integrity in electrical interconnections in the background art.

[0028] This optical communication system can be applied to signal transmission between boards such as server motherboards, switch / router boards, and high-performance testing instruments; it can also be applied to AR / VR headsets and ultra-thin laptops to connect high-performance computing units and high-resolution displays; it can also be applied to autonomous vehicles to connect high-resolution cameras, LiDAR, central computing platforms, etc., to process and transmit sensor data; and it can also be applied to ultra-large-scale data centers and high-performance computing clusters to realize data transmission between server racks and within the data center.

[0029] Combination Figure 1 As shown, in one embodiment of the present invention, the light transmission module 30 includes a first lens 32, a second lens 33 and a light transmission element 31. The first lens 32 is attached to the light-emitting side of the light-emitting element 11, the second lens 33 is attached to the light-incident side of the photodetector 21, and the two ends of the light transmission element 31 are connected to the first lens 32 and the second lens 33. The light emitted by the light-emitting element 11 is focused by the first lens 32 to the light-conducting element 31 and then conducted to the second lens 33, which focuses the light onto the photodetector 21.

[0030] In this embodiment, the first lens 32 is closely attached to or aligned with the light-emitting side surface of the light-emitting element 11. Specifically, the first lens 32 can be a miniature trapezoidal lens, hemispherical lens, cylindrical lens, or aspherical lens, fabricated on the chip of the light-emitting element 11 through photoresist hot melt reflow, micro-nano imprinting, or direct bonding processes. Alternatively, the first lens 32 can be fabricated on an independent transparent substrate (such as glass) and then aligned and bonded to the chip. The function of the first lens 32 is to collimate or converge the light beam emitted by the light-emitting element 11 with a certain divergence angle, so that more light can be efficiently transmitted to the port of the light-transmitting element 31, reducing the spillover loss of light in free space transmission, and thus reducing signal crosstalk between adjacent channels in a multi-channel architecture.

[0031] The second lens 33 is attached to the light-incident side of the photodetector 21. The second lens 33 is used to refocus or refocus the light beam emitted from the light conductor 31, which may have some divergence, onto the photosensitive area of ​​the photodetector 21, thereby further improving the light signal reception efficiency and thus enhancing the signal reception sensitivity and signal-to-noise ratio of the optical communication system.

[0032] The optical transmission element 31 serves as the transmission medium for optical signals. Its two ends are coupled to the first lens 32 and the second lens 33, respectively. After being shaped by the first lens 32, the optical signal enters the optical transmission element 31 and is transmitted over long distances within it via total internal reflection or waveguide confinement. Finally, it is directed to the second lens 33 and focused onto the receiving surface of the photodetector 21. This lens-waveguide-lens structure not only compensates for the alignment difficulties caused by the small size of the light-emitting element 11 and the detector but also improves the coupling efficiency of the entire optical link. This allows the system to achieve stable and reliable communication even at lower transmission power, extending the effective transmission distance.

[0033] Furthermore, the optical transmission module 30 also includes a sealing layer 40, which is a transparent adhesive layer. The sealing layer 40 is disposed on the end face of the first lens 32 facing the light-emitting element 11 and the end face of the second lens 33 facing the photodetector 21, sealing the gap between the first lens 32 and the light-emitting element 11 and the gap between the second lens 33 and the photodetector 21, so as to improve the sealing effect of the optical communication system.

[0034] In one embodiment of the present invention, the light transmission element 31 is an optical fiber. The optical fiber can be a multimode fiber or a single-mode fiber. The core diameter of the optical fiber is adapted to the light-emitting surface size of the light-emitting element 11 and the light-receiving surface size of the photodetector 21 to improve alignment accuracy and reduce transmission loss.

[0035] In terms of connection methods, optical fibers can be permanently fixed and coupled to lenses or light sources by fusion splicing or UV-cured optical adhesive bonding; of course, optical fibers can also be directly coupled by placing the end face of the optical fiber directly close to the lens or light source and aligning it to achieve optical coupling.

[0036] Using optical fiber as the optical transmission component 31, compared to metal wires, optical fiber offers a wider transmission bandwidth and lower signal attenuation. This enables this optical communication system to achieve interconnections ranging from centimeter-level chip-to-chip to kilometer-level room-to-room interconnections. Simultaneously, optical fiber is immune to electromagnetic interference and can operate stably in complex electromagnetic environments, ensuring signal integrity. The lightweight and flexible nature of optical fiber also allows for flexible cabling and saves space.

[0037] In one embodiment of the present invention, the light-emitting element 11 is a Micro LED. The light-emitting area of ​​the Micro LED is small, for example, a few micrometers, and the pixel center-to-center spacing can reach tens of micrometers to achieve high-density integration. Its emission wavelength can be in the visible to near-infrared light range, such as 450 nm, 850 nm, or 1310 nm.

[0038] Combination Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the light emitting module includes a plurality of Micro LEDs, the light receiving module includes a plurality of photodetectors 21, and the light transmission module 30 includes a plurality of optical fibers, each optical fiber receiving the light signal emitted by a Micro LED and transmitting it to a photodetector 21.

[0039] In this embodiment, the light emitting module includes multiple Micro LEDs (e.g., 64, 128 or more), which are densely integrated on a chip or other type of integrated circuit in a regular two-dimensional matrix (e.g., 8×8, 16×8); of course, multiple Micro LEDs can also be integrated on a chip or other type of integrated circuit in an irregular arrangement.

[0040] Accordingly, the light receiving module includes multiple photodetectors 21, the number, arrangement, and spacing of which are consistent with the Micro LED array at the transmitting end. The multiple photodetectors 21 are integrated on a chip or other form of integrated circuit, and each photodetector 21 is responsible for receiving and converting light signals from a corresponding transmitting channel.

[0041] The optical transmission module 30 comprises multiple optical fibers, which form an optical fiber array. Each optical fiber forms an optical link, with one end optically coupled to a Micro LED and the other end coupled to a photodetector 21. The multiple Micro LEDs, multiple photodetectors 21, and multiple optical fibers form multiple parallel optical paths, i.e., multiple data channels. Each data channel is relatively independent, avoiding optical crosstalk between channels and improving the signal-to-noise ratio and signal integrity of the optical communication system.

[0042] Combination Figure 1 As shown, in one embodiment of the present invention, the optical communication system further includes a first chip 132, a second chip 242, a first flexible circuit board 131, and a second flexible circuit board 241; the first chip 132 is packaged in the first flexible circuit board 131, the second chip 242 is packaged in the second flexible circuit board 241, a plurality of light-emitting elements 11 are integrated in the first chip 132 and electrically connected to the first flexible circuit board 131; a plurality of photodetectors are integrated in the second chip 242 and electrically connected to the second flexible circuit board 241.

[0043] In this embodiment, the substrate of the first flexible circuit board 131 can be polyimide (PI) or other polymers, possessing excellent flexibility, heat resistance, and electrical insulation. Simultaneously, the first flexible circuit board 131 contains circuitry, and a connection terminal is provided at one end of the first flexible circuit board 131 for connecting to an external communication port. The light-emitting element 11 is integrated onto the first chip 132 and electrically connected to the circuitry of the first flexible circuit board 131.

[0044] The bendable nature of the first flexible circuit board 131 allows the light emitting module to be folded or installed in irregular, narrow spaces, achieving a compact layout in three-dimensional space.

[0045] The light-emitting element 11 is mounted on the first chip 132, or the light-emitting element 11 and the first chip 132 are fabricated simultaneously using semiconductor processing technology, so that the light-emitting element 11 is integrated on the first chip 132. The first chip 132 is mounted on the first flexible circuit board 131, so the light-emitting element 11 can be electrically connected to the first flexible circuit board 131 through the first chip 132.

[0046] Similarly, the photodetector 21 and signal processor 22 are integrated onto the second chip 242, and the second chip 242 is packaged onto the second flexible circuit board 241. Therefore, the photodetector 21 and signal processor 22 can be electrically connected to the second flexible circuit board 241 through the second chip 242. The bendability of the second flexible circuit board 241 allows the light receiving module to be folded or installed in irregular, narrow spaces, achieving a compact layout in three-dimensional space.

[0047] Since the light-emitting element 11 and the photodetector 21 are respectively disposed on different chips, the first chip 132 and the second chip 242 can be spaced apart and arranged relative to each other. At the same time, multiple optical fibers are disposed between the first chip 132 and the second chip 242 and coupled to the light-emitting element 11 and the photodetector 21 respectively. The light-emitting element 11 on the first chip 132 is used to emit optical signals, and the photodetector 21 on the second chip 242 is used to receive optical signals, so as to realize multi-channel data transmission.

[0048] Combination Figure 2 As shown, in one embodiment of the present invention, the optical communication system includes a first chip 132, a second chip 242, a first flexible circuit board 131, and a second flexible circuit board 241. The first chip 132 is packaged on the first flexible circuit board 131, and the second chip 242 is packaged on the second flexible circuit board 241; Both the first chip 132 and the second chip 242 integrate a light-emitting element 11 and a photodetector 21. The light-emitting element 11 and the photodetector 21 integrated in the first chip 132 are electrically connected to the first flexible circuit board 131; the light-emitting element 11 and the photodetector 21 integrated in the second chip 242 are electrically connected to the second flexible circuit board 241.

[0049] In this embodiment, the specific structures of the first chip 132, the second chip 242, the first flexible circuit board 131, and the second flexible circuit board 241 can be referred to the description in the above embodiments, and will not be further elaborated here. In this embodiment, multiple light-emitting elements 11 are partially integrated on the first chip 132 and partially integrated on the second chip 242; multiple photodetectors 21 are partially integrated on the first chip 132 and partially integrated on the second chip 242. That is, the first chip 132 has both light-emitting elements 11 and photodetectors 21, and the second chip 242 has both light-emitting elements 11 and photodetectors 21. The first chip 132 and the second chip 242 are arranged opposite each other, and multiple optical fibers are arranged between the first chip 132 and the second chip 242. The light-emitting elements 11 on the first chip 132 are connected to the photodetectors 21 on the second chip 242 through optical fibers to achieve signal transmission, and the light-emitting elements 11 on the second chip 242 are connected to the photodetectors 21 on the first chip 132 through optical fibers to achieve signal transmission. The multiple light-emitting elements 11 and multiple photodetectors 21 on the first chip 132 can be arranged alternately along the row and column directions, or the multiple light-emitting elements 11 can be arranged in one area of ​​the first chip 132, and the multiple photodetectors 21 can be arranged in another area of ​​the first chip 132. Similarly, the multiple light-emitting elements 11 and multiple photodetectors 21 on the second chip 242 can be arranged in the same way.

[0050] In one embodiment of the present invention, the photodetector 21 is a spin photodetector.

[0051] In this embodiment, the spin photodetector is not a traditional photodiode based on a semiconductor PN junction, but a device that utilizes the spin property of electrons for photoelectric conversion. The energy of the incident photons is absorbed by the magnetic material layer (such as CoFeB, CoPt, etc.) of the spin photodetector, causing a sharp increase in the local electron temperature, which in turn changes the magnetization state (such as the magnetic moment direction or magnetization intensity) of the magnetic layer through thermal effects. This change in magnetic state directly leads to a change in the overall resistance of the spin photodetector. By detecting this resistance change, the intensity of the incident light signal can be determined; alternatively, a voltage can be applied across the spin photodetector, and the intensity of the incident light signal can be determined by detecting changes in current. Since the above process mainly relies on the spin of electrons under the influence of a magnetic field, rather than the generation and migration of charge carriers as in traditional semiconductors, the response time of the spin photodetector is extremely short, reaching the picosecond level, and the parasitic capacitance of the device is extremely small.

[0052] When light shines on a spin photodetector, its resistance changes. Applying a constant bias voltage Vbias across the spin photodetector causes the current difference across it to change accordingly (ΔI = Vbias / ΔR). The signal processor 22 can be a comparator, analog-to-digital converter, dynamic latch amplifier (such as a PCSA), or other device with signal conversion capabilities to "determine" discrete digital "0" or "1" from a continuous analog signal. For example, when the signal processor 22 is a comparator, it can be a voltage comparison circuit. In this case, applying a constant bias current Ibias across the spin photodetector will cause the voltage difference across it to change with the resistance of the spin photodetector (ΔV = Ibias * ΔR). The comparator has a preset reference voltage Vref, which is compared with the analog voltage change signal of the spin photodetector. The comparator's output changes when the input analog voltage exceeds the reference voltage Vref threshold, thereby converting the analog light intensity signal into a digital "0" or "1" signal output.

[0053] In traditional optical receiver modules that use semiconductor photodetectors to detect optical signals, the semiconductor photodetectors (such as PIN-PDs or APDs) generate weak, continuous photocurrent signals (typically in the microampere range) under illumination. This signal has high impedance and low amplitude characteristics, making it easily overwhelmed by noise in the circuit. Therefore, the current signal output by a traditional semiconductor photodetector must first be converted into a processable voltage signal by a transimpedance amplifier (TIA), introducing as little noise as possible in the process. However, the TIA itself has a gain-bandwidth product limitation, and its noise (especially the input reference noise current) directly determines the receiver's sensitivity limit. To compensate for channel loss, a continuous-time linear equalizer (EQ) and a multi-stage limiting amplifier (LA) are usually cascaded after the TIA to amplify the signal and shape it into a digital level that meets the required amplitude. This complex analog front-end not only consumes a lot of power but also limits the system's signal response rate and sensitivity.

[0054] In stark contrast, the spin photodetector used in this application directly converts optical signals into varying resistances within the device. When a constant bias voltage or current is applied, the change in resistance is directly converted into a large-amplitude voltage or current signal. That is, under light pulse illumination, the electrical signal at both ends of the spin photodetector can instantly switch from one level to another with a significantly different amplitude. Therefore, the output signal itself possesses sufficient amplitude and edge steepness to be output to a comparator for threshold decision-making, eliminating the need for signal amplification and impedance conversion via a TIA, and the need for complex waveform restoration via an additional EQ. The receiving link is simplified from the traditional multi-stage structure of "PD→TIA→EQ→LA→signal processor 22" to a two-stage structure of "spin PD→signal processor 22". This not only significantly reduces the power consumption and design complexity of analog circuits, but also eliminates the noise-bandwidth trade-off of TIA from limiting system performance. The bandwidth of the optical receiver module is theoretically limited only by the physical response speed of the spin photodetector itself (which can reach the picosecond level) and the decision speed of the signal processor 22, thereby realizing an optical communication module with high response speed, wider bandwidth, higher sensitivity, and high energy efficiency.

[0055] In addition, traditional semiconductor photodetectors cannot achieve both sensitivity and speed when miniaturized. Spin photodetectors, because their working principle does not rely on the photosensitive area to collect photons, have a low correlation between their intrinsic response speed and device capacitance. Therefore, even when the size is reduced to the submicron level, they can still maintain an ultrafast picosecond response and sufficient signal amplitude, thus meeting the requirements of "small size, high speed, and high sensitivity".

[0056] Understandably, due to the unique performance advantages of spin photodetectors, the area of ​​the light-incident side facing the light transmission module 30 can be set smaller than the area of ​​the light-outcident side facing the light transmission module 30. Designing a smaller area on the light-incident side of the spin photodetector effectively reduces its parasitic capacitance, thus significantly improving the response speed of the spin photodetector. Furthermore, based on the unique photoelectric conversion mechanism of the spin photodetector, excellent optical signal detection sensitivity can be maintained even with a smaller photosensitive area. Additionally, the detection bandwidth of the spin photodetector 12B increases as the device size decreases, contributing to higher system integration density and data transmission rates in optical communication modules. This design effectively overcomes the performance contradiction between response speed and sensitivity caused by size limitations in traditional semiconductor photodetectors, thereby significantly improving the overall performance of the optical communication module. When the light-emitting element 11 is a Micro LED, the Micro LED itself is relatively small. Since the size of the spin photodetector does not limit the response speed and sensitivity, the spin photodetector can be designed to be smaller than the Micro LED to reduce the volume of the optical communication module, or more Micro LEDs and spin photodetectors can be set in the same volume of the optical communication module, thereby increasing the number of channels of the optical communication module.

[0057] In one embodiment, the spin photodetector is a magnetic tunnel junction photodetector (MTJ PD). The MTJ PD is a vertically stacked thin-film structure, comprising, from bottom to top, a bottom electrode, a pinned / reference layer, a tunnel barrier layer, a free layer, and a top electrode. The bottom electrode may include multiple layers of metal such as tantalum (Ta) / ruthenium (Ru) for connecting electrical signals. The pinned / reference layer comprises a ferromagnetic alloy (such as CoFeB) with a fixed magnetization direction, which remains unchanged during device operation, providing a reference for resistance changes. The tunnel barrier layer can be an ultrathin magnesium oxide (MgO) single-crystal layer with a thickness on the nanometer scale. The free layer is composed of ferromagnetic materials (such as CoFeB, NiFe), but its magnetization direction changes under light / heat, achieving high-sensitivity light detection. The top electrode is a transparent or semi-transparent conductive layer, such as an ultrathin indium tin oxide (ITO) or a metal several nanometers thick (such as Ta / Ru), allowing light signals to penetrate and act on the free layer, while the top electrode connects to electrical signals.

[0058] When a light pulse strikes the free layer through the top electrode, the photon energy is rapidly absorbed and converted into heat in the lattice and electron spin system, causing the free layer temperature to rise sharply within picoseconds. This instantaneous temperature rise significantly reduces the magnetic anisotropy of the free layer, causing a transient deflection or precession of its magnetization vector. The relative angle (θ) between the magnetization directions of the free layer and the reference layer thus changes. According to the magnetoresistance effect of the magnetic tunnel junction, the resistance R of the spin optoelectronic device satisfies the relationship: R = R0 / (1 + TMR * cosθ), where R0 is the antiparallel state resistance and TMR is the tunneling magnetoresistance ratio. Therefore, even a tiny change in magnetization angle θ can be converted into a detectable device resistance signal R. This process is completely different from the mechanism in semiconductor photodiodes where electron-hole pairs are generated and then migrate under the influence of an electric field, thus avoiding the limitations imposed by carrier drift velocity and diffusion capacitance on the response speed, thereby achieving a high-speed response.

[0059] In other embodiments, in addition to magnetic tunnel junction photodetectors (MTJ PD), spin photodetectors can also be detectors that utilize the "optical-electron spin-charge" coupling mechanism, such as spin-seebeck photodetectors and multiferroic tunnel junction (MFTJ) photodetectors.

[0060] In one embodiment, combined with Figure 4 As shown, the photodetector 21 includes a first spin photodetector 211 and a second spin photodetector 212; The first spin photodetector 211 is configured to receive the light signal emitted by the light-emitting element 11 as a sensing detector. The second spin photodetector 212 is configured not to receive the light signal emitted by the light-emitting element 11 as a reference detector; The signal processor 22 is configured to receive the differential signal output by the first spin photodetector 211 and the second spin photodetector 212.

[0061] In this embodiment, the first spin photodetector 211 and the second spin photodetector 212 can be made of the same materials, structure, and process, and integrated on the same semiconductor substrate (such as a silicon substrate). The spacing between them is small, for example, less than 10 micrometers, to ensure that the environmental parameters such as the temperature environment, mechanical stress, and process fluctuations experienced by the first spin photodetector 211 and the second spin photodetector 212 tend to be consistent.

[0062] The first spin photodetector 211 is aligned and coupled to the output end of the light-conducting element 31 to receive light signals from the light-emitting element 11, thus serving as a sensing detector. The surface of the second spin photodetector 212 is covered by a light-shielding structure to prevent it from receiving light signals from the light-conducting element 31. The light-shielding structure can be an opaque metal layer (such as aluminum or tungsten) or a dark polymer (such as polyimide). By covering the surface of the second spin photodetector 212 with the light-shielding structure, the second spin photodetector 212 is exposed to the same environmental interference (such as temperature fluctuations, power supply noise, substrate noise, etc.) as the first spin photodetector 211, without responding to signal light, thus serving as a reference detector.

[0063] In the circuit connection, the first spin photodetector 211 and the second spin photodetector 212 are connected to a bias signal source (e.g., bias voltage or bias current), and the output of the bias signal source is connected to the signal processor 22. When only ambient noise (such as increased ambient temperature) is present, the resistances of the two spin photodetectors will change in the same direction and with equal amplitude. At this time, the voltage changes generated at the input of the signal processor 22 cancel each other out, making the differential input voltage ΔV≈0. However, when the light signal only illuminates the first spin photodetector 211, it will cause an additional change in the resistance of the first spin photodetector 211, thereby generating a differential voltage signal, which is then output to the signal processor 22.

[0064] This differential architecture actively cancels noise interference introduced by environmental factors and inherent circuit defects, further improving the signal-to-noise ratio and sensitivity of the optical communication module. This allows the optical communication module to operate stably at lower received optical power, thereby extending the communication distance. Simultaneously, it reduces the requirements for power supply stability and ambient temperature control, improving the system's robustness and reliability.

[0065] The spin photodetector (e.g., a magnetic tunnel junction photodetector) described in this application differs fundamentally from traditional semiconductor photodetectors (such as Si PIN or InGaAs APDs) in its information retention capability. A traditional semiconductor photodetector is essentially a passive, volatile photo-to-electric conversion element: it only generates a photocurrent output of "1" when an external reverse bias is applied and there is illumination; otherwise, it outputs "0". Once power is off, it does not store any state information internally; it cannot record whether the device has just received a light pulse, nor can it retrieve historical signals after power failure. In other words, traditional semiconductor photodetectors can only achieve real-time response and do not have memory storage capabilities.

[0066] In contrast, the spin photodetector in this application utilizes the magnetization direction of the ferromagnetic free layer as an information carrier, possessing non-volatile storage capability. When a light pulse of specific polarization or energy irradiates the spin photodetector, it drives the magnetic moment of the free layer to flip from the parallel (P) state to the antiparallel (AP) state (or from the AP state to the P state). Since the P state and AP state correspond to low-resistance and high-resistance states, respectively, and this state is maintained by the magnetic anisotropy of the material itself, the magnetization direction can be maintained for a long time even if the power supply is completely cut off. Therefore, the spin photodetector can not only output an electrical signal at the moment of illumination, but also store the event of "whether a valid light signal has been received" in the form of a resistance state, realizing the integrated function of signal transmission and storage.

[0067] Therefore, in the event of a sudden power outage or in sleep mode, the optical communication module can still read the resistance state of the spin photodetector upon subsequent power-up to restore the last communication content, making it suitable for high-reliability communication scenarios (such as aerospace and industrial control). Secondly, it can simplify the optical communication system architecture: eliminating the need for SRAM caching or Flash writing circuits required to maintain the state in traditional solutions.

[0068] Combination Figure 3 As shown, in one embodiment of the present invention, the light emitting module further includes a driver 12, which is electrically connected to the light emitting element 11.

[0069] In this embodiment, the driver 12 includes a current modulation circuit for converting a digital voltage signal from an upstream circuit (such as a serializer) into a high-precision current pulse capable of driving the Micro LED to emit light. The driving circuitry included in the driver 12 can be integrated onto a substrate or base plate and electrically interconnected with the Micro LED chip via micro-bumps to reduce parasitic inductance and resistance in the driving path. The driver 12 can be manufactured using advanced semiconductor fabrication processes, enabling high integration with the light-emitting element 11, feedforward equalizer, etc., achieving miniaturization and low power consumption.

[0070] Combination Figure 1 As shown, in one embodiment of the present invention, the light emitting module further includes a first equalizer 14, which is electrically connected to the driver 12 and the light-emitting element 11. The first equalizer 14 is used to equalize and enhance the high-frequency driving signal generated by the driver 12.

[0071] The first equalizer 14 is located at the signal output terminal of the driver 12. It can perform pre-distortion processing on the input digital signal waveform to enhance the high-frequency components of the signal and compensate for the inherent attenuation of high-frequency components by subsequent devices or links (Micro LED, packaging, etc.).

[0072] With or without limitation, the light emitting module includes a first equalizer 14, and the light receiving module further includes a second equalizer 23, which is electrically connected to the photodetector 21 and the signal processor 22. The second equalizer 23 is used to equalize and enhance the high-frequency analog signal generated by the photodetector 21.

[0073] The second equalizer 23 is electrically connected between the output of the photodetector 21 and the input of the signal processor 22. Since the signal output by the spin photodetector is essentially an analog voltage or current signal generated by modulating the bias current or voltage through its resistance change ΔR, although this signal has an ultrafast edge, its high-frequency components are attenuated after passing through printed circuit board traces, package interconnects, and other channels. The main function of the second equalizer 23 is to perform amplitude compensation and phase correction on the analog signal output by the spin photodetector, thereby equalizing and enhancing the high-frequency analog signal generated by the photodetector 21.

[0074] The above are merely exemplary embodiments of the present invention and do not limit the scope of the patent of the present invention. All equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. An optical communication system, characterized in that, The optical communication system includes: A light emitting module, comprising a light-emitting element and used to emit light; An optical receiving module includes a photodetector and a signal processor. The photodetector and the signal processor are communicatively connected. The photodetector receives the light emitted by the light-emitting element and converts it into an analog signal. The signal processor reads the analog signal generated by the photodetector and outputs a digital signal. A flexible circuit board, wherein both the light emitting module and the light receiving module are electrically connected to the flexible circuit board, and A light transmission module is provided, which is located between the light emitting module and the light receiving module, and transmits the light emitted by the light-emitting element to the photodetector.

2. The optical communication system as described in claim 1, characterized in that, The light transmission module includes a first lens, a second lens, and a light transmission element. The first lens is attached to the light-emitting side of the light-emitting element, the second lens is attached to the light-incident side of the photodetector, and the two ends of the light transmission element are connected to the first lens and the second lens. The light emitted by the light-emitting element is focused by the first lens onto the light-conducting element and then conducted to the second lens, which focuses the light onto the photodetector.

3. The optical communication system as described in claim 2, characterized in that, The optical transmission element is an optical fiber.

4. The optical communication system as described in claim 3, characterized in that, The light-emitting element is a Micro LED.

5. The optical communication system as described in claim 4, characterized in that, The light emitting module includes multiple MicroLEDs, the light receiving module includes multiple photodetectors, and the light transmitting module includes multiple optical fibers. Each optical fiber receives the light signal emitted by one of the MicroLEDs and transmits it to one of the photodetectors.

6. The optical communication system as described in claim 5, characterized in that, The optical communication system includes a first chip, a second chip, a first flexible circuit board, and a second flexible circuit board; The first chip is packaged on the first flexible circuit board, and the second chip is packaged on the second flexible circuit board; Multiple light-emitting elements are integrated into the first chip and electrically connected to the first flexible circuit board; Multiple photodetectors are integrated into the second chip and electrically connected to the second flexible circuit board.

7. The optical communication system as described in claim 5, characterized in that, The optical communication system includes a first chip, a second chip, a first flexible circuit board, and a second flexible circuit board; The first chip is packaged on the first flexible circuit board, and the second chip is packaged on the second flexible circuit board; Both the first chip and the second chip integrate the light-emitting element and the photodetector. The light-emitting element and the photodetector integrated in the first chip are electrically connected to the first flexible circuit board; the light-emitting element and the photodetector integrated in the second chip are electrically connected to the second flexible circuit board.

8. The optical communication system as described in any one of claims 1 to 7, characterized in that, The photodetector is a spin photodetector; And / or, the signal processor is a comparator.

9. The optical communication system as described in any one of claims 1 to 7, characterized in that, The light emitting module also includes a driver, which is electrically connected to the light-emitting element.

10. The optical communication system as described in claim 9, characterized in that, The light emitting module also includes a first equalizer, which is electrically connected to the driver and the light-emitting element. The first equalizer is used to equalize and enhance the high-frequency driving signal generated by the driver. And / or, the optical receiving module further includes a second equalizer, which is electrically connected to the photodetector and the signal processor, and is used to equalize and enhance the high-frequency analog signal generated by the photodetector.

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