CPO silicon light engine

Abstract

The invention relates to the technical field of optical communication, and provides a CPO silicon optical engine, which comprises an optical emission assembly, the optical emission assembly comprises a wavelength demultiplexer, a micro-ring modulator array and a wavelength multiplexer, the wavelength demultiplexer is used for dividing an incident multi-wavelength light beam into multiple paths of light beams with single mode length, the micro-ring modulator array is used for dividing the light beams with single mode length into multiple paths of light beams with single mode length, and the wavelength multiplexer is used for dividing the light beams with single mode length into multiple paths of light beams with single mode length. And the micro-ring modulator array is used for carrying out electro-optical signal modulation on the light subjected to beam splitting by the wavelength demultiplexer, and the wavelength multiplexer is used for combining multiple paths of light beams with different wavelengths modulated by the micro-ring modulator array into one path of multi-wavelength light beam and outputting the multi-wavelength light beam. According to the CPO silicon optical engine, high integration of a modulation channel array is realized by adopting a micro-ring modulator, on-chip receiving end integration is realized by adopting a polarization demultiplexing scheme, channels are combined by adopting a wavelength multiplexer based on a cascade multimode Bragg grating filter, the number of optical IO ports is reduced, the single-fiber transmission bandwidth is increased, an external light source scheme is adopted, and the CPO silicon optical engine has the advantages of high integration degree, high integration degree and high integration degree. The occupied space is reduced, and the heat dissipation pressure is reduced.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a CPO silicon photonics engine. Background Technology

[0002] The digital economy has become a national strategy, and artificial intelligence (AI), as its core driving force, has placed higher demands on computing infrastructure. Computing servers mainly consist of computing units, storage units, and high-speed optical interconnect components.

[0003] Traditional pluggable optical modules suffer from significant signal loss due to the large distance (tens of centimeters) between the optoelectronic chip and the ASIC chip. This loss necessitates high-power devices such as digital signal processors (DSPs), drivers, and serializers / deserializers (SerDes) for signal compensation and shaping, greatly increasing the energy consumption for data transmission.

[0004] CPO (Co-packaged Optoelectronics) technology integrates the switching chip and the optical engine into a single package, significantly shortening the transmission distance and improving transmission efficiency. It is expected to reduce energy consumption by 60%. The core value of this technology lies in the significant improvement in energy efficiency and integration.

[0005] In CPO applications, due to the limited space of silicon photonic chips, it is necessary to solve the problem of high-density integration of transceiver channel arrays and the contradiction between the large number of optical I / O (input / output) and the limited physical space. Summary of the Invention

[0006] The purpose of this invention is to provide a CPO silicon photonics engine that can at least solve some of the defects in the prior art.

[0007] To achieve the above objectives, embodiments of the present invention provide the following technical solution: a CPO silicon photonics engine, comprising an optical emitting component, wherein the optical emitting component includes a wavelength demultiplexer, a micro-ring modulator array, and a wavelength multiplexer.

[0008] The wavelength demultiplexer is used to split an incident single-path multi-wavelength beam into multiple single-mode beams.

[0009] The micro-ring modulator array is used to modulate the signal of the light after it has been split by the wavelength demultiplexer.

[0010] The wavelength multiplexer is used to combine multiple beams of different wavelengths modulated by the micro-ring modulator array into a single multi-wavelength beam for output.

[0011] Furthermore, the micro-ring modulator array includes a thermally adjustable phase shifter, which controls the transmittance of the input light wavelength by adjusting the operating voltage, thereby regulating the operating point of the micro-ring modulator.

[0012] Furthermore, a monitoring detector is provided in the optical path of the micro-ring modulator array, which is used to determine whether the locked operating point is correct.

[0013] Furthermore, each micro-ring modulator in the micro-ring modulator array is equipped with three monitoring detectors, and the operating point can be locked by any two of the monitoring detectors.

[0014] Furthermore, both the wavelength multiplexer and the wavelength demultiplexer include several cascaded multimode Bragg grating filters, with each stage of the multimode Bragg grating filter having an independent wavelength.

[0015] Furthermore, the wavelength multiplexer and the wavelength demultiplexer are the same device and are made of silicon nitride material.

[0016] Furthermore, it also includes an optical receiving component, which comprises a polarization beam splitter rotator, a wavelength demultiplexer, and a detector array.

[0017] The polarization beam splitter is used to separate the input TM0 and TE0 mode light and convert the TM0 mode to the TE0 mode. The polarization beam splitter operates in the wavelength range of 1271~1600nm.

[0018] The wavelength demultiplexer is used to demultiplex the single-channel multi-wavelength optical signal from the receiving end.

[0019] The detector array is used to receive the optical signal separated by the wavelength demultiplexer and convert the optical signal into an electrical signal.

[0020] Furthermore, the polarization beam splitter rotator includes a mode converter and a mode wavelength demultiplexer.

[0021] The mode converter is used to convert TM0 mode light into TE1 mode light, and the operating wavelength range of the mode converter is between 1271 and 1600 nm.

[0022] The mode wavelength demultiplexer is used to separate TE1 mode light and TE0 mode light in the same optical path and convert TE1 mode to TE0 mode. The operating wavelength range of the mode wavelength demultiplexer is between 1271 and 1600 nm.

[0023] Furthermore, it also includes an external light source assembly, which is connected to the light emitting assembly via a polarization-maintaining fiber.

[0024] Furthermore, the external light source assembly includes a laser chip, a spatial coupling module, and a wavelength multiplexer, wherein the laser chip and the wavelength multiplexer are spatially coupled through the spatial coupling module.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. A high degree of integration of the modulation channel array is achieved by using a micro-ring modulator.

[0027] 2. A polarization demultiplexing scheme is used to achieve on-chip receiver integration.

[0028] 3. Wavelength multiplexing is used to combine channels, reducing the number of optical I / O ports and increasing the single-fiber transmission bandwidth.

[0029] 4. An external light source solution is adopted to reduce space occupation and heat dissipation pressure. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a CPO silicon photonics engine provided in an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of an external light source for a CPO silicon photonics engine provided in an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of a light-emitting component of a CPO silicon photonics engine provided in an embodiment of the present invention;

[0033] Figure 4 A graph showing the relationship between the wavelength and transmittance of the input light of a CPO silicon photonics engine provided in an embodiment of the present invention;

[0034] Figure 5 A schematic diagram of a microring modulator with three mPDs arranged in the optical path of a CPO silicon photonics engine provided in an embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram of the structure of a CPO silicon photonics engine optical receiving component provided in an embodiment of the present invention;

[0036] Figure 7 A schematic diagram of the normalized spectral curves of three mPD photocurrents of a CPO silicon photonics engine provided in an embodiment of the present invention.

[0037] Figure 8 This is a schematic diagram of a microring modulator array that uses the microring itself to realize wavelength multiplexers and wavelength demultiplexers in traditional technology.

[0038] Figure 9 The spectrum of each microring in a microring modulator array that implements wavelength multiplexers and wavelength demultiplexers based on the microrings themselves in traditional technology;

[0039] Figure 10The spectral diagram of each microring in a microring modulator array employing a Bragg grating wavelength MUX / DEMUX in a CPO silicon photonics engine provided in an embodiment of the present invention. Detailed Implementation

[0040] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Please see Figure 1 , Figures 3 to 5 This invention provides a CPO silicon photonics engine, including a light emitting component comprising a wavelength demultiplexer, a micro-ring modulator array, and a wavelength multiplexer. The wavelength demultiplexer splits an incident single-path multi-wavelength beam into multiple single-mode beams. The micro-ring modulator array modulates the beams split by the wavelength demultiplexer using an electro-optic signal. The wavelength multiplexer combines the multiple beams of different wavelengths modulated by the micro-ring modulator array into a single multi-wavelength beam for output. Preferably, the micro-ring modulator array includes a thermally adjustable phase shifter. The thermally adjustable phase shifter controls the transmittance of the input light wavelength without a microwave signal by adjusting the operating voltage, thereby controlling the operating point of the micro-ring modulator. A monitoring detector is disposed on the optical path of the micro-ring modulator array to determine whether the locked operating point is correct. Each micro-ring modulator in the micro-ring modulator array is equipped with three monitoring detectors, and the operating point is locked by any two of these monitoring detectors. In this embodiment, the optical emitting component of this application employs a micro-ring modulator to achieve high integration of the modulation channel array. A polarization demultiplexing scheme is used to achieve on-chip receiver integration. Specifically, as... Figure 3 As shown, the TX silicon photonics chip comprises a wavelength demultiplexer (DEMUX), a microring modulator (MRM) array, and a wavelength multiplexer (MUX). The TX silicon photonics chip and the external light source are connected via polarization-maintaining fiber, ensuring that the light entering the TX silicon photonics chip is in TE mode. The incident multi-wavelength light is split into multiple single-mode wavelengths by the wavelength demultiplexer, then modulated by the MRM array to complete the electro-optic signal, and finally combined into a single wavelength multiplexer, which is connected to the output of the TX silicon photonics chip. The MRM needs to operate at a specific operating point, such as... Figure 4As shown, the transmittance corresponding to the input light wavelength needs to be at -3dB or -5dB, which requires adjusting the voltage of the thermal phase shifter on the MRM. To lock onto this operating point, a monitoring detector (mPD) needs to be set up in the MRM optical path to determine whether the desired operating point has been locked, such as... Figure 5 As shown, an MRM can be configured with three mPDs, and the operating point can be locked by selecting any two of them. Specifically, the three mPDs are mPD1, mPD2, and mPD3, and their photocurrents follow the following relationship: I_mPD1≈I_mPD2+I_mPD3, where "≈" reflects the absorption and scattering losses present in the microring. Based on this relationship, the target operating point can be locked by the photocurrent of any two mPDs. When the target operating point is 3 dB, the specific locking method is as follows: using mPD1 and mPD2 for locking requires satisfying 10*log10(I_mPD2 / I_mPD1)=3dB, as shown below. Figure 7 As shown, if the three photocurrents are normalized and expressed in dB, the equivalent is I_mPD1−I_mPD2 = 3 dB. Using mPD1 and mPD3 for locking, I_mPD1−I_mPD3≈3 dB should be satisfied. Using mPD2 and mPD3 for locking, I_mPD2≈I_mPD3≈3 dB should be satisfied.

[0042] As an optimized solution for an embodiment of the present invention, please refer to Figures 8 to 10 In the optical emission assembly, both the wavelength multiplexer and the wavelength demultiplexer include several cascaded multimode Bragg grating filters, with each stage of the multimode Bragg grating filter having an independent wavelength. Preferably, the wavelength multiplexer and the wavelength demultiplexer are the same device and are fabricated using silicon nitride material. Traditional optical emission schemes utilize a micro-ring modulator itself to achieve wavelength multiplexing / demultiplexing. For example... Figure 8 As shown, when a beam of light with four wavelengths (λ1, λ2, λ3, λ4) enters the micro-ring modulator array, and the resonant wavelengths of the four micro-ring modulators are tuned to near λ1, λ2, λ3, and λ4 respectively, then the four micro-ring modulators simultaneously achieve wavelength multiplexing, electro-optic modulation, and wavelength demultiplexing. This scheme has a simple structure, but it has the following problems: Figure 9 As shown, 1. To achieve multi-wavelength multiplexing, all wavelengths need to be accommodated within one FSR (Free Spectral Region) of the micro-ring modulator. This requires a small diameter for the micro-ring modulator, resulting in a large half-wave voltage and insufficient modulation depth. 2. The spacing between multiple wavelengths is very small, typically only 1-2 nm. Such multi-wavelength light sources are not commercially viable and require the development of specific optical frequency comb light sources. 3. Each micro-ring modulator needs to have its unique operating point locked to a specific wavelength via a thermal phase shifter, such as... Figure 9As shown by the black dots, each micro-ring channel has only one operating point, making locking difficult. 4. The receiver also requires a micro-ring modulator for wavelength demultiplexing, necessitating precise control of the thermal phase shifter within the micro-ring to lock the wavelength, increasing locking difficulty and circuit complexity. This embodiment combines a Bragg grating filter with a micro-ring modulator. [The following text appears to be unrelated and possibly a separate document fragment:] ...as Figure 3 As shown, the Bragg grating filter acts as both a wavelength multiplexer and demultiplexer, while the microring modulator itself only needs to perform electro-optic modulation. This approach offers the following advantages over traditional techniques that only use microring modulators: 1. It eliminates the requirement for the FSR of the microring modulator, allowing for a larger diameter and improved modulation capability; 2. It allows for the use of conventional coarse wavelength division multiplexing (CWDM) light sources, which are readily available and cost-effective; 3. Each microring modulator has multiple operating points corresponding to specific wavelengths, such as... Figure 10 As shown by the black dot, each micro-ring channel has 5 operating points, reducing the difficulty of locking; 4. The receiver wavelength demultiplexer adopts a Bragg grating wavelength demultiplexer, which has a sufficiently wide channel spectrum (18nm) and can be compatible with wavelengths that vary freely within ±9nm. It is a passive device and does not require fine-tuning and locking, resulting in higher stability.

[0043] Please see Figure 6The CPO silicon photonics engine further includes an optical receiving component, which comprises a polarization beam splitter, a wavelength demultiplexer, and a detector array. The polarization beam splitter separates the input TM0 and TE0 mode light and converts the TM0 mode to the TE0 mode, with an operating wavelength range of 1271–1600 nm. The wavelength demultiplexer demultiplexes the single-path multi-wavelength optical signal at the receiving end. The detector array receives the optical signal separated by the wavelength demultiplexer and converts it into an electrical signal. Preferably, the polarization beam splitter has a mode converter and a mode-wavelength demultiplexer. The mode converter converts the TM0 mode light to the TE1 mode light, with an operating wavelength range of 1271–1600 nm. The mode-wavelength demultiplexer separates the TE1 mode light and TE0 mode light in the same optical path and converts the TE1 mode to the TE0 mode, with an operating wavelength range of 1271–1600 nm. The wavelength demultiplexer is composed of cascaded multimode Bragg grating filters. In this embodiment, wavelength multiplexing is used for channel combining, reducing the number of optical I / O ports and increasing the single-fiber transmission bandwidth. Specifically, the optical receiving component consists of a polarization beam splitter (PBRS), a wavelength demultiplexer, and a detector (PD) array. Since the polarization entering the RX silicon photonics chip generally includes both TEO and TMO modes, but the silicon photonics chip only allows the TEO mode, it is necessary to convert the TMO mode to the TEO mode and separate it from the original TEO mode light. This function requires the use of PBRS. Considering that the RX silicon photonics chip needs to operate in a wide wavelength range (1271-1600nm), the PBRS needs to have the capability of wide-spectrum operation. The PBRS device here consists of two parts, the first being the TMO... The TE1 device converts TM0 to TE1 mode while leaving TE0 unchanged. Then comes the mode demultiplexer. When the TE1 and TE0 modes coexisting in the same optical path enter the demultiplexer, the TE1 mode light couples into a branch and is converted to TE0 mode, while the TE0 mode continues to propagate along the main path. Thus, a beam containing both TE0 and TM0 modes is converted into two TE0 mode beams after passing through the PBRS, one of which is entirely converted from the original TM0 mode light. Both TE0 mode beams after passing through the PBRS contain multiple wavelengths of optical signal, requiring a wavelength demultiplexer for wavelength demultiplexing. For example... Figure 6 As shown, the two 1271nm light streams separated by the two wavelength demultiplexers enter the same detector (PD), with each PD corresponding to a wavelength signal. This enables each PD to acquire optical signals in all modes (TE and TM) for each wavelength and convert them into electrical signals.

[0044] Please see Figure 2 The CPO silicon photonics engine further includes an external light source assembly, which is connected to the optical emitting assembly via a polarization-maintaining fiber. Preferably, the external light source assembly includes a laser chip, a spatial coupling module, and a wavelength multiplexer, with the laser chip and the wavelength multiplexer spatially coupled via the spatial coupling module. In this embodiment, an external light source solution is used to reduce space occupation and heat dissipation pressure. Specifically, as... Figure 2As shown, the light source of the optical engine is externally mounted. The light source consists of a laser (LD) chip, a spatial coupling module (lens, isolator), and a wavelength multiplexer. Benefiting from the CWDM (coarse wavelength division multiplexing) characteristics of cascaded multimode Bragg gratings, the LD chip can use standard CWDM wavelengths. The CWDM wavelength distribution is based on the ITU-T G.694.2 standard, with a channel spacing of 20 nm, covering a band from 1271 nm to 1611 nm, for a total of 18 wavelength channels. The wavelength multiplexer is composed of cascaded multimode Bragg grating filters. Thanks to the wavelength independence of each stage of the grating filter in this wavelength multiplexer, the multiplexed wavelengths can be arbitrarily selected as needed. For example, in 8-wavelength multiplexing, wavelengths of 1271 nm, 1291 nm, 1311 nm, 1331 nm, 1351 nm, 1371 nm, 1411 nm, and 1431 nm can be selected, avoiding the water absorption peak at 1391 nm. The wavelength multiplexer chip uses silicon nitride (SiN), whose refractive index is insensitive to temperature, allowing the wavelength multiplexer to operate stably over a wide temperature range. The LD chip uses standard CWDM (coarse wavelength division multiplexing) wavelengths. The CWDM wavelength distribution is based on the ITU-T G.694.2 standard, with a channel spacing of 20 nm, covering a band from 1271 nm to 1611 nm, for a total of 18 wavelength channels. Spatial coupling between the LD chip and the wavelength multiplexer chip is achieved through lenses and isolators. Preferably, the external light source assembly is placed inside a first housing, which has an opening for the polarization-maintaining fiber to extend out of the first housing. The optical emitting assembly and the optical receiving assembly are also located inside a second housing, which has an opening for the polarization-maintaining fiber to enter, facilitating connection between the polarization-maintaining fiber and the optical reflecting assembly. In existing technologies, the light source is usually placed directly inside the second housing, which occupies space within the second housing. Externalizing the light source can significantly save space within the second housing. However, we have found that externalizing the light source can lead to reduced EMI performance due to the fiber passing through the opening. Therefore, this embodiment cleverly designs an EMI magnetic ring at the opening, and provides a toothed structure on the ring body of the EMI magnetic ring. On the one hand, the EMI magnetic ring can provide EMI protection at the opening; on the other hand, the toothed structure on the ring body can increase the friction between the EMI magnetic ring and the polarization-maintaining fiber, thereby limiting the polarization-maintaining fiber and preventing it from moving arbitrarily and pulling on the light emitting component. Preferably, the toothed structure can be integrally formed on the ring body or bonded to the ring body.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A CPO silicon photonic engine, comprising a light-emitting component, characterized in that: The optical emitting component includes a wavelength demultiplexer, a micro-ring modulator array, and a wavelength multiplexer. The wavelength demultiplexer is used to split an incident single-path multi-wavelength beam into multiple single-mode beams. The micro-ring modulator array is used to modulate the signal of the light after it has been split by the wavelength demultiplexer. The wavelength multiplexer is used to combine multiple beams of different wavelengths modulated by the micro-ring modulator array into a single multi-wavelength beam for output.

2. A CPO silicon photonics engine as described in claim 1, characterized in that: The micro-ring modulator array includes a thermally adjustable phase shifter, which controls the transmittance of the input light wavelength by adjusting the operating voltage, thereby regulating the operating point of the micro-ring modulator.

3. A CPO silicon photonic engine as described in claim 2, characterized in that: A monitoring detector is provided on the optical path of the micro-ring modulator array, and the monitoring detector is used to determine whether the locked operating point is correct.

4. A CPO silicon photonics engine as described in claim 3, characterized in that: Each micro-ring modulator in the micro-ring modulator array is equipped with three monitoring detectors, and the operating point can be locked by any two of the monitoring detectors.

5. A CPO silicon photonic engine as described in claim 1, characterized in that: Both the wavelength multiplexer and the wavelength demultiplexer include several cascaded multimode Bragg grating filters, with each stage of the multimode Bragg grating filter having an independent wavelength.

6. A CPO silicon photonic engine as described in claim 1, characterized in that: The wavelength multiplexer and the wavelength demultiplexer are the same device and are made of silicon nitride material.

7. A CPO silicon photonic engine as described in claim 1, characterized in that: It also includes an optical receiving component, which comprises a polarization beam splitter rotator, a wavelength demultiplexer, and a detector array. The polarization beam splitter is used to separate the input TM0 and TE0 mode light and convert the TM0 mode to the TE0 mode. The polarization beam splitter operates in the wavelength range of 1271~1600nm. The wavelength demultiplexer is used to demultiplex the single-channel multi-wavelength optical signal from the receiving end. The detector array is used to receive the optical signal separated by the wavelength demultiplexer and convert the optical signal into an electrical signal.

8. A CPO silicon photonics engine as described in claim 7, characterized in that: The polarization beam splitter rotator has a mode converter and a mode wavelength demultiplexer. The mode converter is used to convert TM0 mode light into TE1 mode light, and the operating wavelength range of the mode converter is between 1271 and 1600 nm. The mode wavelength demultiplexer is used to separate TE1 mode light and TE0 mode light in the same optical path and convert TE1 mode to TE0 mode. The operating wavelength range of the mode wavelength demultiplexer is between 1271 and 1600 nm.

9. A CPO silicon photonic engine as described in claim 1, characterized in that: It also includes an external light source assembly, which is connected to the light emitting assembly via a polarization-maintaining fiber.

10. A CPO silicon photonics engine as described in claim 9, characterized in that: The external light source assembly includes a laser chip, a spatial coupling module, and a wavelength multiplexer. The laser chip and the wavelength multiplexer are spatially coupled through the spatial coupling module.

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