Communication system between silicon optical chips based on dual-port output Mach-Zehnder modulator

Abstract

The invention discloses a silicon optical inter-chip communication system based on a dual-port output Mach-Zehnder modulator, and belongs to the technical field of inter-chip communication. An optical signal emitted by a laser is subjected to 1: 1 light splitting through a first multimode interferometer and then enters a first phase modulation arm and a second phase modulation arm to be subjected to phase modulation, and the two paths of modulated optical signals pass through a first thermal adjustment phase shifter and a second thermal adjustment phase shifter respectively to compensate phase errors. And the two paths of optical signals subjected to phase compensation realize dual-port output through a second multi-mode interferometer and are transmitted to a balance photoelectric detector on a receiving end chip, and photocurrent subtraction of the two paths of optical signals is performed in the balance photoelectric detector to obtain enhanced signal output. Compared with a traditional direct modulation and direct detection inter-core communication mode, the receiving sensitivity can be doubled, and guiding significance is achieved for development of the optical interconnection technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of inter-chip communication, and in particular relates to a silicon photonic inter-chip communication system based on a dual-port output Mach-Zehnder modulator. Background Art

[0002] With the booming development of emerging application fields such as the Internet of Things, large-scale artificial intelligence, and cloud computing, the demand for large-capacity communications between and within data centers is growing, which places increasingly high demands on the design of high-performance, low-power, and multifunctional semiconductor chips. With the iteration of advanced processes, the approaching physical limit size of transistors and the exponential growth in the cost of new process development, traditional single-chip system-on-chip (SoC) technology will make it more difficult to improve chip technology. In addition, SoCs are usually manufactured using the same process and materials, and there are inherent limitations on the interconnection speed and bandwidth between their internal functional modules.

[0003] To meet the above challenges, chiplet technology came into being, opening up a new path for chip design. The core concept of chiplet technology is to build a larger-scale and more complex chip system through precise combination of miniaturized and function-specific integrated circuit IP modules. This is different from the design of SoC, in which all components (such as CPU, GPU, memory, I / O interface, etc.) are integrated on a silicon wafer. Chiplet is a small-scale circuit manufactured separately to perform specific functions or tasks, and is interconnected through 3D stacking or advanced packaging technology combined with advanced interconnect technology. Chiplet technology has the main advantages of high yield, low cost, high integration, powerful performance, good flexibility, and fast time to market. Among them, the new interface interconnection is the key to chiplet technology, which refers to the use of new technologies and materials to achieve high-speed, low-power, and high-reliability interconnection between chips to improve the performance and efficiency of chip systems.

[0004] The progress of silicon photonic high-speed transceiver systems, especially the realization of silicon photonic interconnection, has injected new vitality into chiplet technology. Common silicon photonic components include Mach-Zehnder interferometers (MZIs), balanced photodetectors (BPDs), and optical attenuators (VOAs). Taking the typical silicon photonic chip MZI-PD optical interconnection structure as an example, the structure first integrates a laser or other light source on the chiplet to generate a focused light beam as an optical signal. These optical signals are modulated by an optical modulator (MZM) to carry digital information. Subsequently, the modulated optical signal is transmitted through an optical waveguide. If necessary, the path can be flexibly adjusted through an optical cross switch to achieve flexible connection between different functional modules inside the chip. The photodetector (PD) is used to detect the optical signal and convert it into an electrical signal for processing at the receiving end. Finally, the signal is processed at the receiving end, involving steps such as demodulation, decryption, and error correction.

[0005] As a new paradigm for data transmission, inter-chip optical interconnect technology uses optical signals instead of traditional electrical signals to transmit data at high speed in the form of laser beams between chiplets and other components (such as CPU, GPU, memory, I / O devices, etc.). This technological innovation marks a breakthrough in the chiplet-based interconnect architecture, introducing new dimensions of speed, bandwidth, and efficiency for data communication within semiconductor packages. However, the sensitivity of the current communication architecture still has room for improvement, so continuous optimization and technological innovation remain the key to the development of this field. Summary of the invention

[0006] In view of the above, the purpose of the present invention is to provide a silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator. By optimizing the inter-chip communication method based on a dual-output Mach-Zehnder modulator and a balanced photodetector, compared with the traditional inter-chip communication method of direct modulation and direct detection, the present invention can double the receiving sensitivity, essentially improve the signal-to-noise ratio (SNR) of the signal, thereby relaxing the requirements on device performance and allowing higher modulation formats, achieving higher-speed inter-chip communication while relatively improving the chip process tolerance, which has guiding significance for the development of optical interconnection technology.

[0007] In order to achieve the above-mentioned invention object, the technical solution provided by the present invention is as follows: An embodiment of the present invention provides a silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator, comprising: a transmitting chip and a receiving chip; The on-chip structure of the transmitting chip includes a laser and a dual-port output Mach-Zehnder modulator, and the structure of the dual-port output Mach-Zehnder modulator includes a first multi-mode interferometer, a first phase modulation arm, a second phase modulation arm, a first thermally modulated phase shifter, a second thermally modulated phase shifter, and a second multi-mode interferometer; the on-chip structure of the receiving chip includes a balanced photodetector; The optical signal emitted by the laser is split 1:1 by the first multimode interferometer and then enters the first phase modulation arm and the second phase modulation arm for phase modulation respectively. The two optical signals after modulation are respectively passed through the first thermal modulation phase shifter and the second thermal modulation phase shifter to compensate for the phase error. The two optical signals after phase compensation are then passed through the second multimode interferometer to achieve dual-port output and transmitted to the balanced photodetector of the receiving chip. The photocurrents of the two optical signals are subtracted in the balanced photodetector to obtain an enhanced signal output.

[0008] Preferably, the on-chip structure of the transmitting end chip further includes a digital-to-analog conversion module, through which the electrical signal is loaded onto the optical signal emitted by the first phase modulation arm and the second phase modulation arm.

[0009] Preferably, the optical field of the two optical signals outputted at the dual ports by the second multimode interferometer is expressed as: , , in, and The two optical signals are The light field, is the light field of the optical signal emitted by the laser, is an imaginary unit, is the driving voltage of the dual-port output Mach-Zehnder modulator, is the half-wave voltage of the dual-port output Mach-Zehnder modulator, is the phase difference between the first phase modulation arm and the second phase modulation arm.

[0010] Preferably, the phase difference between the first phase modulation arm and the second phase modulation arm is adjusted by at least one of the first thermal phase shifter and the second thermal phase shifter.

[0011] Preferably, when the phase difference between the first phase modulation arm and the second phase modulation arm is When the photocurrent of the two optical signals is subtracted in the balanced photodetector, the enhanced signal output is expressed as: , in, and are the photocurrents of the optical signal, and are the conjugate of the two optical signal fields, is the photocurrent of the output enhanced signal.

[0012] Preferably, the method further comprises: when the phase difference between the first phase modulation arm and the second phase modulation arm is When the photocurrent of the two optical signals is subtracted in the balanced photodetector, the enhanced signal output is expressed as: .

[0013] Preferably, the first phase modulation arm and the second phase modulation arm are both push-pull type.

[0014] Preferably, the first thermal phase shifter and the second thermal phase shifter change the propagation path of the optical signal in the waveguide by heating or cooling the waveguide, thereby adjusting the phase of the optical signal.

[0015] The present invention proposes a novel inter-core communication method based on a dual-port output Mach-Zehnder modulator and balanced photodetector reception. Compared with the prior art, the present invention has at least the following beneficial effects: (1) The signal strength is improved, which effectively improves the receiving sensitivity. Since the effective signal strength of the present invention is twice as high as that of the communication method of single-output Mach-Zehnder modulator and single photodetector reception, it can effectively improve the receiving sensitivity and signal quality of inter-core communication.

[0016] (2) It can allow higher modulation formats, effectively improving the communication capacity of inter-core communication. The improvement of receiving sensitivity means that this communication method has a higher signal-to-noise ratio. A higher signal-to-noise ratio allows a higher modulation order. Under the same signal baud rate, the higher the order, the higher the rate.

[0017] (3) Improved performance while keeping the chip area unchanged. Compared with the traditional method, the chip area of ​​this invention is only increased at the receiving end, but since the area of ​​the on-chip photodetector is very small, this increase can be basically ignored, and the chip area of ​​the transmitting end remains unchanged.

[0018] (4) The tolerance for insufficient chip performance caused by the process is relatively improved, which indirectly improves the yield rate. Since the invention can essentially improve the receiving sensitivity of communication, it can compensate for the insufficient chip performance caused by the process to a certain extent, so that it can still meet the basic inter-chip communication requirements, save costs and improve the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 is a structural schematic diagram of a silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator provided by an embodiment of the present invention; Figure 2 It is a structural schematic diagram of the silicon photonic chip-to-chip communication system based on a single-port output Mach-Zehnder modulator and a single photodetector receiver. DETAILED DESCRIPTION

[0021] To make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0022] like Figure 1As shown, an embodiment of the present invention provides a silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator, including: a transmitter chip and a receiver chip. The on-chip structure of the transmitter chip includes a laser 1, a first multimode interferometer 2, a first phase modulation arm 3, a digital-to-analog conversion module 4, a second phase modulation arm 5, a first thermally modulated phase shifter 6, a second thermally modulated phase shifter 7, and a second multimode interferometer 8. The on-chip structure of the receiver chip includes a balanced photodetector 9. Among them, the first multimode interferometer 2, the first phase modulation arm 3, the second phase modulation arm 5, the first thermally modulated phase shifter 6, the second thermally modulated phase shifter 7, and the second multimode interferometer 8 together constitute a dual-port output Mach-Zehnder modulator.

[0023] The optical signal emitted by the laser 1 is split 1:1 by the first multimode interferometer 2, and then enters the push-pull first phase modulation arm 3 and the second phase modulation arm 5 for phase modulation. At the same time, the electrical signal is loaded onto the optical signal emitted by the first phase modulation arm 3 and the second phase modulation arm 5 by the digital-to-analog conversion module 4. The two optical signals after modulation are then passed through the first thermal phase shifter 6 and the second thermal phase shifter 7 to statically compensate for the phase error caused by the chip manufacturing process. The two optical signals after phase compensation are then passed through the second multimode interferometer 8 to achieve dual-port output and transmitted to the balanced photodetector 9 of the receiving chip. The optical field of the two optical signals that achieve dual-port output by the second multimode interferometer is expressed as: , , in, and The two optical signals are The light field, is the light field of the optical signal emitted by the laser, is an imaginary unit, is the driving voltage of the dual-port output Mach-Zehnder modulator, is the half-wave voltage of the dual-port output Mach-Zehnder modulator; is the phase difference between the first phase modulation arm 3 and the second phase modulation arm 5 , which is adjusted by the first thermal phase shifter 6 or the second thermal phase shifter 7 .

[0024] and The two paths of light enter the balanced photodetector 9 of the receiving end chip together, and the output of the balanced photodetector 9 is the subtraction of the photocurrents of the two photodetectors, that is , when the phase difference When , the output photocurrent is expressed as: , in, and are the photocurrents of the optical signal, and are the conjugate of the two optical signal fields, is the photocurrent of the output enhanced signal.

[0025] When the phase difference When , the output photocurrent is expressed as: .

[0026] The enhanced signal output by the balanced photodetector 9 can be compared with Figure 2 Shown is a comparison of the standard single-port Mach-Zehnder modulator transmitting and single photodetector receiving communication modes. Figure 2 The first multimode interferometer 2, the first phase modulation arm 3, the second phase modulation arm 5, the first thermally adjustable phase shifter 6, the second thermally adjustable phase shifter 7, and the third multimode interferometer 10 together constitute a single-port output Mach-Zehnder modulator.

[0027] like Figure 2 As shown, the output light field of the chip laser 1 at the transmitting end is also recorded as , after 1:1 splitting by the first multimode interferometer 2, they enter the push-pull first phase modulation arm 3 and the second phase modulation arm 5 for phase modulation, and at the same time, the electrical signal is loaded onto the optical signal emitted by the first phase modulation arm 3 and the second phase modulation arm 5 through the digital-to-analog conversion module 4. The two optical signals after modulation are then passed through the first thermal phase shifter 6 and the second thermal phase shifter 7 to statically compensate for the phase error caused by the chip manufacturing process. The two optical signals after phase compensation are then coupled by the third multimode interferometer 10 to achieve single-port output. The output optical field is recorded as , transmitted to the photodetector 11 of the receiving end chip. The expression is as follows: , in, is the driving voltage of the single-port output Mach-Zehnder modulator, is the half-wave voltage of the single-port output Mach-Zehnder modulator, and the phase difference between the two arms is By adjusting at least one of the first thermal phase shifter 6 and the second phase shifter 7 to 0. The receiving end chip is composed of a separate photodetector 11. The output of the transmitting end chip enters the receiving end chip after transmission, and the photocurrent is received by the photodetector 11 to obtain , as shown in formula (6): , Comparing equation (4) with equation (6), the communication method based on the dual-port output Mach-Zehnder modulator and balanced photodetector reception has an effective signal strength twice as high as the communication method based on the traditional standard single-port output Mach-Zehnder modulator and single photodetector reception, which greatly improves the receiving sensitivity and signal quality. In addition, since the traditional chip system does not provide a flexible choice of the number of ports, this innovative design not only breaks through the limitations of existing technologies, but also significantly optimizes the detection performance of optical signals. It contains a profound theoretical foundation and technological innovation, and has far-reaching guiding significance for the development of optical interconnection technology.

[0028] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator, characterized in that: Including a transmitter chip and a receiver chip; The on-chip structure of the transmitting chip includes a laser and a dual-port output Mach-Zehnder modulator, and the structure of the dual-port output Mach-Zehnder modulator includes a first multi-mode interferometer, a first phase modulation arm, a second phase modulation arm, a first thermally modulated phase shifter, a second thermally modulated phase shifter, and a second multi-mode interferometer; the on-chip structure of the receiving chip includes a balanced photodetector; The optical signal emitted by the laser is split 1:1 by the first multimode interferometer and then enters the first phase modulation arm and the second phase modulation arm for phase modulation respectively. The two optical signals after modulation are respectively passed through the first thermal modulation phase shifter and the second thermal modulation phase shifter to compensate for the phase error. The two optical signals after phase compensation are then passed through the second multimode interferometer to achieve dual-port output and transmitted to the balanced photodetector of the receiving chip. The photocurrents of the two optical signals are subtracted in the balanced photodetector to obtain an enhanced signal output.

2. The silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator according to claim 1, characterized in that: The on-chip structure of the transmitting end chip also includes a digital-to-analog conversion module, through which the electrical signal is loaded onto the optical signal emitted by the first phase modulation arm and the second phase modulation arm.

3. The silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator according to claim 1, characterized in that: The optical field of the two optical signals outputted at the dual ports by the second multimode interferometer is expressed as: ， ， in, and The two optical signals are The light field, is the light field of the optical signal emitted by the laser, is an imaginary unit, is the driving voltage of the dual-port output Mach-Zehnder modulator, is the half-wave voltage of the dual-port output Mach-Zehnder modulator, is the phase difference between the first phase modulation arm and the second phase modulation arm.

4. The silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator according to claim 3, characterized in that: The phase difference between the first phase modulation arm and the second phase modulation arm is adjusted by at least one of the first thermally adjustable phase shifter and the second thermally adjustable phase shifter.

5. The silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator according to claim 3, characterized in that: When the phase difference between the first phase modulation arm and the second phase modulation arm When the photocurrent of the two optical signals is subtracted in the balanced photodetector, the enhanced signal output is expressed as: ， in, and are the photocurrents of the optical signals, and are the conjugate of the two optical signal fields, is the photocurrent of the output enhanced signal.

6. The silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator according to claim 5, characterized in that: Also included is that when the phase difference between the first phase modulation arm and the second phase modulation arm When the photocurrent of the two optical signals is subtracted in the balanced photodetector, the enhanced signal output is expressed as: 。 7. The silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator according to claim 1, characterized in that: The first phase modulation arm and the second phase modulation arm are both push-pull type.

8. The silicon photonic chip-to-chip communication system based on a dual-port output Mach-Zehnder modulator according to claim 1, characterized in that: The first thermal phase shifter and the second thermal phase shifter change the propagation optical path of the optical signal in the waveguide by heating or cooling the waveguide, thereby adjusting the phase of the optical signal.

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