800G single-fiber bidirectional silicon optical chip, 800G single-fiber bidirectional silicon optical device and working point voltage control method

Abstract

The invention provides an 800G single-fiber bidirectional silicon optical chip, a device and a working point voltage control method, and relates to the field of chip manufacturing, and the silicon optical chip comprises four transmitters with different single-wave wavelengths of 200G and four receivers with different single-wave wavelengths of 200G which are integrated in the silicon optical chip. Optical signals of the transmitter and the receiver are coupled through the micro-ring resonator and the chip I / O COM waveguide, and the chip I / O COM waveguide transmits single-fiber bidirectional 800G optical signals to the outside through an external optical fiber. A photon integrated loop is constructed by using a modulator formed by four single-wave 200G emitting electrodes with different wavelengths and a receiver and a micro-ring resonator, and an external optical fiber connected with an external laser is mixed and integrated to the photon integrated loop to provide a light source, so that the transmission function of a chip in a single-fiber bidirectional 800G optical signal is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of optical communication chips and devices, and in particular to an 800G single-fiber bidirectional silicon photonic chip, device, and operating point voltage control method. Background Art

[0002] The training of large AI models requires massive computing resources, and computing card manufacturers in the industry have emerged one after another to explore the possibility of various network technology innovations. The switches currently used in AI supercomputing are still electrical switches. All-optical switches based on OXC technology (Optical Cross-Connect) replace existing electrical chip switches, which is a technological trend. OXC has two built-in micromirror arrays. Micromirror array 1 deflects the incident signal to the micromirror unit corresponding to micromirror array 2 by adjusting the angle, mapping the light from the input port to the output port, thereby realizing the exchange of optical signals between the two paths. The entire process is a passive operation, which can greatly reduce the power consumption of the switch. At present, North America has begun to deploy OXC switches for AI supercomputing applications.

[0003] Since the channel resources of OXC switches are relatively tight, single-fiber bidirectional optical modules need to be connected to reduce the fiber channel budget. 800G single-fiber bidirectional optical modules have begun to be used in small batches in this field, but the eight-channel EML solution is currently used. The internal device packaging of the optical module is very complex, and the cost and yield of the optical module are facing great pressure. Silicon photonics has many advantages such as small size, high integration, low cost, and easy production. However, the 800G single-fiber bidirectional optical module using silicon photonics is still blank in the research field and market. Summary of the invention

[0004] The technical problem to be solved by the present invention is that, in order to overcome the defects of the above-mentioned prior art, the present invention provides an 800G single-fiber bidirectional silicon photonic chip, device and working point voltage control method.

[0005] The present invention provides an 800G single-fiber bidirectional silicon photonic chip, comprising four transmitters with different single-wavelengths of 200G and four receivers with different single-wavelengths of 200G integrated inside the silicon photonic chip, wherein the optical signals of the transmitters and the receivers are coupled through a microring resonator and a chip I / O COM waveguide, and the chip I / O COM waveguide transmits the single-fiber bidirectional 800G optical signal to the outside through an external optical fiber.

[0006] Compared with the prior art, the 800G single-fiber bidirectional silicon photonic chip of the present application has the following advantages: a photonic integrated circuit is constructed by using a modulator and a micro-ring resonator composed of a single-wavelength 200G transmitter and receiver with four different wavelengths, and an external optical fiber connected to an external laser is hybridly integrated into the photonic integrated circuit to provide a light source, thereby realizing the chip's single-fiber bidirectional 800G optical signal transmission function.

[0007] In a possible implementation, each of the transmitters includes a CW Laser light source chip and a transmitter microring resonator; the CW Laser light source chip is electrically connected to a pad on one side of the CW laser coupling step of a silicon photonic chip, the CW Laser light source chip waveguide is submicron-coupled with a light source optical input waveguide, the light source optical input waveguide is input to a single-wave 200G MZM modulator, and the MZM modulator is output to an MZM output waveguide; depending on whether the resonant wavelength of the transmitter microring resonator matches the output wavelength of the CW Laser light source chip, the optical signal of the MZM output waveguide enters the chip I / O COM waveguide output or enters the MZM-MPD backlight detector.

[0008] Compared with the existing technology, the direction of the optical signal can be conveniently controlled by the resonant wavelength of the transmitter microring resonator and the light output wavelength of the CW Laser light source chip.

[0009] In a possible implementation manner, the end faces of the CW Laser light source chip waveguide and the light source light inlet waveguide relative to the silicon photonic chip are both inclined surfaces.

[0010] Compared with the existing technology, the waveguides on both sides are beveled relative to the chip end face to resist return loss and improve the performance of silicon photonic chips.

[0011] In a possible implementation manner, the MZM modulator is provided with an MZM heating resistor for adjusting the phase difference between two arms of the MZM modulator.

[0012] In a possible implementation, a TXMR heating resistor for adjusting the resonant wavelength of the transmitter microring resonator is provided on the transmitter microring resonator.

[0013] In a possible implementation, each of the receivers includes a receiver microring resonator and a single-wavelength 200G PD, the receiver microring resonator outputs to an RXMR downstream output waveguide, and the input optical signal of the external optical fiber is input to a chip I / O COM waveguide; depending on whether the resonant wavelength of the receiver microring resonator matches a wavelength of the input optical signal, the receiver microring resonator is coupled to the single-wavelength 200G PD through the RXMR downstream output waveguide.

[0014] In a possible implementation, the receiver microring resonator is provided with an RXMR heating resistor for adjusting the resonant wavelength of the receiver microring resonator.

[0015] In a possible implementation, the CW Laser light source chip includes a CW laserInP substrate, a CW laser active area waveguide, a CW laser electrode and a CW laser electrode pre-solder which are stacked in sequence; the silicon photonic chip includes a silicon waveguide Cladding, a silicon waveguide, a silicon dioxide layer, a silicon substrate and a silicon photonic chip electrode; the silicon waveguide Cladding, the silicon waveguide and the silicon dioxide layer are stacked up and down in sequence above one side of the silicon substrate, and the silicon photonic chip electrode is arranged above the other side of the silicon substrate; the silicon photonic chip electrode and the CW laser electrode are electrically connected.

[0016] Compared with the existing technology, the CW laser electrode is pre-set with solder, and the solder is heated, pressurized and melted to connect the two chips, which plays the three roles of high-strength fixation, electrical conduction and thermal conduction; the silicon waveguide and the CW laser active area waveguide are coupled and aligned at the submicron level through a high-precision placement machine, and the coupling gap is filled with refractive index matching glue to achieve further matching of the mode fields on both sides, reducing coupling insertion loss and return loss. At the same time, the refractive index matching glue also plays a role in protecting the end faces of the chips on both sides, increasing the stability and reliability of the long-term working end faces of the chips.

[0017] The present application also provides a device of an 800G single-fiber bidirectional silicon photonic chip, including a device BGA high-frequency packaging substrate, a TEC thermoelectric controller for controlling the temperature of the silicon photonic chip, four 200G MZ driver chips for amplifying a single-wave 200G electrical signal input from a module / system mainboard and then loading it on the MZM, four 200G TIA chips for amplifying a single-wave 200G electrical signal for high-speed PD output and then outputting it to the module / system mainboard, a silicon photonic working point control IC chip for sampling MPD and PD photocurrent and controlling a heating resistor on the adjustment chip to make it work at the optimal bias voltage position, and a single-channel FA; The TEC thermoelectric controller is mounted with a silicon photonic chip and a thermistor; the four 200G MZ driver chips, four 200G TIA chips and a silicon photonic working point control IC chip are all mounted on the device BGA high-frequency packaging substrate 307; the single-channel FA and the chip I / O COM waveguide are coupled and fixed on the TEC thermoelectric controller.

[0018] Compared with the existing technology, a BGA silicon photonic device is designed. Through the internal packaging of the thermoelectric controller and the silicon photonic operating point control IC with integrated ADC / DAC, the thermoelectric controller makes the wavelength of the laser more stable and the three-temperature performance of the microring resonator more stable; the silicon photonic operating point control IC can quickly complete the debugging of 12 heater bias voltage operating points and perform real-time control after the device is powered on, reducing the device's dependence on the client MCU control resources.

[0019] The present application also provides a method for controlling the operating point voltage of an 800G single-fiber bidirectional silicon photonic chip, comprising the following steps: Step 1, respectively scan the voltage of the TXMR heating resistors of the four transmitters, monitor the four corresponding MZM-MPD backlight detector current curves, set the voltage of the TXMR heating resistor to the maximum point of the MZM-MPD backlight detector current, confirm that no light enters the transmitter microring resonator at this time, and proceed to the next step; Step 2: Set the operating points of the four MZM heating resistors: Scan the voltage of the MZM heating resistors of the four transmitters respectively, monitor the voltage curves of the four MZM-MPD backlight detectors, and set the operating point voltage of the MZM heating resistor to the 3dB operating point of the MZM modulator; Step 3: Set the operating point thresholds and operating points of the four TXMR heating resistors: Scan the voltages of the TXMR heating resistors of the four transmitters respectively, monitor the current curves of the four MZM-MPD backlight detectors, set the operating point threshold voltage of the TXMR heating resistor to an operating point of 5% of the maximum photocurrent point of the MZM-MPD backlight detector, and set the operating point voltage of the TXMR heating resistor to an operating point of the minimum current point of the MZM-MPD backlight detector; Step 4: Scan the voltage of the RXMR heating resistors of the four receivers respectively, monitor the photocurrent curves of the four single-wave 200G PDs, set the voltage of the RXMR heating resistor to the minimum current point of the single-wave 200G PD, confirm that no light enters the receiver microring resonator at this time, and proceed to the next step; Step 5. Set the operating point thresholds and operating points of the four RXMR heating resistors: Scan the voltages of the four RXMR heating resistors respectively, monitor the four single-wave 200G PD photocurrent curves, take 95% of the maximum point of the single-wave 200G PD photocurrent as the resonance point threshold of the receiver microring resonator, and set the voltage to the maximum point of the single-wave 200G PD photocurrent; Step 6: Feedback the operating point threshold voltage and operating point voltage on the silicon photonic chip to the module / system mainboard.

[0020] Compared with the existing technology, a working point control method and process of 800G single-fiber bidirectional silicon photonic devices are given, which can quickly and stably control the working point of the silicon photonic chip, so that the chip can work with high reliability for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the functional block diagram of the 800G single-fiber bidirectional silicon photonic chip; Figure 2 This is a cross-sectional diagram of CW laser and silicon optical coupling; Figure 3This is the functional block diagram of 800G single-fiber bidirectional silicon optical devices; Figure 4 These are two silicon photonic chip wavelength meters for 800G single-fiber bidirectional transmission; Figure 5 This is a schematic diagram of the light entering and exiting the TX1 MZM (the light path is in the direction of the arrow); Figure 6 is the curve of MZM-MPD photocurrent changing with the MZM heating resistor voltage; Figure 7 This is a schematic diagram of the optical path of the MZM output light coupling coupled to the COM waveguide output through the TXMR (the optical path is along the direction of the arrow); Figure 8 is the curve of MZM-MPD photocurrent changing with TXMR heating resistor voltage; Fig. 9 This is a schematic diagram of the optical path of the COM waveguide light output to the high-speed PD through RXMR coupling (the optical path is along the direction of the arrow); Fig.10 It is the curve of the high-speed PD photocurrent changing with the RXMR heating resistor voltage; Fig.11 It is a flow chart of the device operating point control method.

[0022] Description of reference numerals: 11-MZM-MPD backlight detector; 111-TX1 MZM-MPD backlight detector; 112-TX2 MZM-MPD backlight detector; 113-TX3 MZM-MPD backlight detector; 114-TX4 MZM-MPD backlight detector; 12-single-wavelength 200G PD; 121-RX1 single-wavelength 200G PD; 122-RX2 single-wavelength 200G PD; 123-RX3 single-wavelength 200G PD; 124-RX4 single-wavelength 200G PD; 1301-light source into optical waveguide; 131-TX1 light source into optical waveguide; 132-TX2 light source into optical waveguide; 133-TX3 light source into optical waveguide; 134-TX4 light source into optical waveguide; 1302-MZM output waveguide; 135-TX1 MZM output waveguide; 136-TX2 MZM output waveguide; 137-TX3 MZM output waveguide; 138-TX4 MZM output waveguide; 1303-RXMR downstream output waveguide; 139-RX1 RXMR downstream output waveguide; 1310-RX2 RXMR downstream output waveguide; 1311-RX3 RXMR downstream output waveguide; 1312-RX4 RXMR downstream output waveguide; 1401-transmitter micro-ring resonator; 141-TX1 transmitter micro-ring resonator; 142-TX2 transmitter micro-ring resonator; 143-TX3 transmitter micro-ring resonator; 144-TX4 transmitter micro-ring resonator; 1402-receiver micro-ring resonator; 145-RX1 receiver micro-ring resonator; 146-RX2 receiver micro-ring resonator; 147-RX3 receiver micro-ring resonator; 148-RX4 receiver micro-ring resonator; 15-MZM modulator; 151-TX1 MZM modulator; 152-TX2 MZM modulator; 153-TX3 MZM modulator; 154-TX4 MZM modulator; 1601-MZM heating resistor; 161-TX1 MZM heating resistor; 162-TX2 MZM heating resistor; 163-TX3 MZM heating resistor; 164-TX4 MZM heating resistor; 1602-TXMR heating resistor; 165-TX1 TXMR heating resistor; 166-TX2 TXMR heating resistor; 167-TX3 TXMR heating resistor; 168-TX4 TXMR heating resistor; 1603-RXMR heating resistor; 169-RX1 RXMR heating resistor; 1610-RX2 RXMR heating resistor; 1611-RX3RXMR heating resistor; 1612-RX4 RXMR heating resistor; 17-CW laser coupling step; 20-CW Laser light source chip; 101-TX1 CW Laser light source chip; 102-TX2 CW Laser light source chip; 103-TX3 CW Laser light source chip; 104-TX4 CW Laser light source chip; 201-CW laser InP substrate; 202-CW laser active area waveguide; 203-CW laser electrode; 204-CW laser electrode pre-solder; 21-silicon photonic chip; 1313-chip I / O COM waveguide; 211-silicon waveguide cladding; 212-silicon waveguide; 213-silicon dioxide layer; 214-silicon substrate; 215-silicon photonic chip electrode; 301-TEC thermoelectric controller; 302-thermistor; 303-200G MZ driver chip; 304-200G TIA chip; 305-silicon photonic working point control IC chip; 306-single-channel FA; 307-device BGA high-frequency packaging substrate. DETAILED DESCRIPTION

[0023] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0024] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0025] In the embodiments of the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0026] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] See also Figure 1 to Figure 5 As shown, the embodiment of the present application discloses that the present invention proposes an 800G single-fiber bidirectional silicon photonic chip and device technical solution, and provides a detailed method and process for controlling the silicon photonic working point.

[0028] It includes four different single-wavelength 200G transmitters (TX) and four different single-wavelength 200G receivers (RX) integrated inside the chip. The optical signals of the transmitters and receivers are coupled through the microring resonator and the COM waveguide. The COM waveguide transmits single-fiber bidirectional 800G optical signals to the outside through external optical fibers.

[0029] Each transmitter includes a CW Laser light source chip 10 , and the CW Laser light source chips 10 of the four channel transmitters are represented by CW Laser light source chip 101 , CW Laser light source chip 102 , CW Laser light source chip 103 , and CW Laser light source chip 104 , respectively.

[0030] See also Figure 1As shown in the figure, taking the 1st channel transmitter (TX1) and the 1st channel receiver (RX1) as examples, the working principle is explained in detail.

[0031] The working principle of the 1st channel transmitter (TX1) is as follows: It includes a TX1 CW Laser light source chip 101, which is a discrete chip of a III-V group material laser and is welded to the corresponding pad on the left side of the CW laser coupling step 17 of the 800G single-fiber bidirectional silicon photonic chip 1 through a flip-chip welding process.

[0032] The TX1 CW Laser light source chip 101 waveguide (III-V group waveguide) and the TX1 light source optical waveguide 131 (silicon waveguide) are coupled and aligned at the sub-micron level by a high-precision placement machine. At the same time, the waveguides on both sides are beveled relative to the chip end face to resist return loss and improve the performance of the TX1 CW Laser light source chip 101.

[0033] The continuous light emitted by the TX1 CW Laser light source chip 101 is coupled into the TX1 light source optical waveguide 131 and input into the TX1 single-wave 200G MZM modulator 151 (Mach-Zehnder modulator). The continuous light signal is modulated into a single-wave 200G high-speed optical signal and output to the TX1 MZM output waveguide 135 .

[0034] The TX1 MZM heating resistor 161 is a heating resistor integrated on the TX1 single-wavelength 200G MZM modulator 151 chip, and is used to adjust the phase difference between the two arms of the TX1 single-wavelength 200G MZM modulator 151 to a suitable operating point of the TX1 single-wavelength 200G MZM modulator 151 .

[0035] Figure 5 A schematic diagram of the light input / output of the TX1 single-wavelength 200G MZM modulator 151 is given, and the light path is along the direction of the arrow. Figure 6 1 is a curve showing the variation of the photocurrent of the TX1 MZM-MPD backlight detector 111 with the voltage of the TX1 MZM heating resistor 161 (MZM-Heater).

[0036] The TX1 MZM heating resistor 161 has a fixed resistance value. By applying voltage for heating, the thermo-optical effect causes a phase difference between the two arms of the single-wave 200G MZM modulator 151. When the relative difference satisfies 0+N×360 degrees, the interference is constructive, and the photocurrent of the TX1 MZM-MPD backlight detector 111 is maximum; when the relative difference satisfies 180+N×360 degrees, the interference is offset, and the photocurrent of the TX1 MZM-MPD backlight detector 111 is minimum.

[0037] The operating point of the TX1 MZM heating resistor 161 is generally set at half (3 dB) of the maximum photocurrent of the TX1 MZM-MPD backlight detector 111 .

[0038] In the embodiment, the mode spot diameter of the waveguide end face of the CW Laser light source chip 101 is 6μm, the mode spot diameter of the end face of the light source light input waveguide 131 is 7μm, the inclination angle of the coupling end face is 2°, the alignment accuracy of the two waveguides is 0.3μm, the coupling loss after the matching glue of the waveguide coupling gap on both sides is 1.5dB, the coupling return loss is 27dB, the refractive index of the matching glue is 1.445, the transmittance is 98%, the modulator working point is controlled at 3.1dB, the CW Laser light source chip 101 output light power is +18.5dBm, and the resistance value of the MZM heating resistor 161 is 120Ω.

[0039] The TXMR heating resistor 165 on the transmitter microring resonator 141 (TXMR) is used to heat and adjust the resonance wavelength of the transmitter microring resonator 141 .

[0040] When the resonance wavelength of the transmitter microring resonator 141 matches the light output wavelength of the CW Laser light source chip 101 , the optical signal of the MZM output waveguide 135 can be coupled to the chip I / O COM waveguide 1313 through the transmitter microring resonator 141 for output.

[0041] When the resonance wavelength of the transmitter microring resonator 141 does not match the light output wavelength of the CW Laser light source chip 101 , the optical signal of the MZM output waveguide 135 will enter the MZM-MPD backlight detector 111 .

[0042] The MZM-MPD backlit detector 111 has three functions: (1) The curve of the photocurrent of the MZM-MPD backlight detector 111 changing with the voltage of the MZM heating resistor 161, and adjusting the voltage of the MZM heating resistor 161 to the optimal working point; (2) The photocurrent of the MZM-MPD backlight detector 111 changes with the voltage of the TXMR heating resistor 165, and the voltage of the MR heating resistor 165 is adjusted to the optimal working point; (3) During the long-term operation of the chip, the photocurrent size of the MZM-MPD backlight detector 111 satisfies the threshold condition to determine whether the voltage of the TXMR heating resistor 165 of the transmitter microring resonator 141 is at the optimal working point. If it is no longer at the optimal working point, the voltage of the TXMR heating resistor 165 is adjusted in real time to keep it at the optimal working point.

[0043] Figure 7A schematic diagram of the optical path of the light output from the TX1 MZM output waveguide 135 coupled to the output of the COM waveguide 1313 through the transmitter microring resonator 141 (TXMR) is given, and the optical path is along the direction of the arrow. Figure 8 It is a curve of the photocurrent of the MZM-MPD backlight detector 111 changing with the voltage of the TXMR heating resistor 165 (TXMR-Heater), and the voltage of the 165_TX1 MR heating resistor is adjusted.

[0044] When the transmitter microring resonator 141 is in the resonant state, light is coupled into the microring, and the photocurrent of the MZM-MPD backlight detector 111 is very small and reaches a valley value. We set a TXMR resonance point MZM-MPD photocurrent threshold. When the current is lower than the threshold, it is considered that the voltage of the current MR heating resistor 165 is at a suitable working point.

[0045] In the embodiment, the resistance value of the MR heating resistor 165 is 120Ω, the current peak value of the MZM-MPD backlight detector 111 is 100uA, the valley value is 0.8uA, the photocurrent threshold of the MZM-MPD backlight detector 111 is 5uA, and when the voltage operating point of the MR heating resistor 165 is reached, the actual optical output power of the device is >+0.5dBm per wavelength.

[0046] The working principle of the 1st channel receiver (RX1) is as follows: COM-MPD115 is used for auxiliary coupling monitoring of external optical fiber and chip I / O COM waveguide 1313.

[0047] The four wavelengths of the external optical fiber input optical signals to the chip I / O COM waveguide 1313 and enter the optical chip. By adjusting the voltage of the RXMR heating resistor 169 on the receiver microring resonator 145 (RXMR), the resonant wavelength of the receiver microring resonator 145 is matched with one of the four wavelengths of the input optical signal. The optical signal can be coupled into the receiver microring resonator 145 and coupled out to the RX1 single-wavelength 200G PD 121 through the RXMR downstream output waveguide 139.

[0048] Fig. 9 A schematic diagram of the optical path of the light entering the COM waveguide and outputting it to the high-speed PD through RXMR coupling is given, and the optical path is along the direction of the arrow. Fig.10 It is the curve of high-speed PD photocurrent changing with RXMR heating resistor (RXMR-Heater) voltage.

[0049] The voltage of the RX1 RXMR heating resistor 169 is adjusted. When the RX1 receiver microring resonator 145 is in the resonant state, light is coupled into the RX1 receiver microring resonator 145, and the photocurrent of the RX1 single-wave 200G PD 121 is very large and reaches a peak value. Then a RXMR resonance point PD photocurrent threshold is set. If the current is higher than the threshold, it is considered that the current voltage of the RX1 RXMR heating resistor 169 is at a suitable working point.

[0050] In this embodiment, the input optical power is 0 dBm per wavelength, the resistance value of the RXMR heating resistor 169 is 120Ω, the high-speed PD current peak is 500 uA, the valley value is 1.2 uA, the high-speed PD photocurrent threshold is 475 uA, and the actual coupling response of the device PD is 0.45 A / W at the voltage operating point of the RXMR heating resistor 169.

[0051] The working principles of the 2nd, 3rd, and 4th channel transmitters (TX2, TX3, TX4) and receivers (RX2, RX3, RX4) are similar and will not be repeated here. A single-channel transmitter and receiver can achieve single-wave 200Gbps signal transmission, and a four-channel transmitter and receiver can achieve four-wave 800Gbps single-fiber bidirectional signal transmission.

[0052] In the present invention, the transmitter and the receiver use two sets of different working wavelengths. Figure 4 The working wavelength table of two 800G single-fiber bidirectional silicon photonic chips is given. The two chips can achieve the interconnection and interoperability of 800G single-fiber bidirectional optical signals.

[0053] In the embodiment, the working wavelengths used are λ1=1273.55 nm, λ2=1277.89 nm, λ3=1282.26 nm, λ4=1286.67 nm, λ5=1295.56 nm, λ6=1300.06 nm, λ7=1304.59 nm, and λ8=1309.14 nm.

[0054] See also Figure 2 The cross-sectional schematic diagram of the coupling between the CW laser light source chip 20 and the silicon photonic chip 1 is shown. The CW laser light source chip 20 is processed based on III-V semiconductor materials and is divided into four layers: CW laser InP substrate 201, CW laser active area waveguide 202, CW laser electrode 203 and CW laser electrode pre-solder 204.

[0055] The silicon photonic chip 21 has a waveguide region on the right side of the CW laser coupling step 17 , including a silicon waveguide cladding 211 , a silicon waveguide 212 , a silicon dioxide layer 213 and a silicon substrate 214 .

[0056] On the left side of the CW laser coupling step 17, three layers 211 to 213 are hollowed out by etching to expose the silicon substrate 214, and a silicon photonic chip electrode 215 is made on the surface of the silicon substrate 214 for connecting with the CW laser 203 electrode to supply power to the CW laser chip 20.

[0057] The CW laser chip 20 is flip-chip mounted on the silicon photonic chip electrode 215 of the silicon photonic chip 21 through the Flipchip welding process. The CW laser electrode is pre-set with solder 204. The solder is heated, pressurized and melted to connect the two chips, playing the three roles of high-strength fixation, electrical conduction and thermal conduction.

[0058] The silicon waveguide 212 and the CW laser active area waveguide 202 are coupled and aligned at the sub-micron level by a high-precision chip mounter, and the coupling gap is filled with 22_ refractive index matching glue to further match the mode fields on both sides and reduce the coupling insertion loss and return loss. At the same time, the refractive index matching glue 22 also protects the chip end faces on both sides, increasing the stability and reliability of the long-term working end faces of the chip.

[0059] In the embodiment, the CW laser electrode pre-set solder 204 used is gold-tin solder, the ratio of gold to tin is 7:3, the melting point is 280° C., the maximum heating temperature of the placement machine is 320° C., the duration is 15 seconds, and the measured placement accuracy is +0.42 μm.

[0060] The functional block diagram of the 800G single-fiber bidirectional silicon optical device in the present invention is as follows: Figure 3 As shown: A 4×200G MZ driver chip 303, a 4×200G TIA chip 304, a silicon photonic operating point control IC chip 305 and a TEC thermoelectric controller 301 are mounted on the device BGA high-frequency packaging substrate 307, and an 800G single-fiber bidirectional silicon photonic chip 21 and a thermistor 302 are surface mounted on the TEC thermoelectric controller 301.

[0061] The function of the TEC thermoelectric controller 301 is to control the temperature of the silicon photonic chip 21, control the laser wavelength and light output power, and improve the three-temperature performance consistency of the silicon photonic core microring resonator.

[0062] The function of the 4×200G MZ driver chip 303 is to amplify the single-wave 200G electrical signal input from the module / system mainboard and load it on the MZM. The function of the 4×200G TIA chip 304 is to amplify the single-wave 200G electrical signal output from the high-speed PD and output it to the module / system mainboard.

[0063] The silicon photonic operating point control IC chip 305 integrates ADC and DAC to sample the MPD and PD photocurrents, and control and adjust the 12 heating resistors on the chip to operate at the optimal bias voltage position.

[0064] After coupling and alignment, the single-channel FA306 and the chip I / O COM waveguide 1313 on the silicon photonic chip 21 are fixedly bonded to the surface of the TEC thermoelectric controller 301, and 800G single-fiber bidirectional optical signal transmission is performed through the single-mode optical fiber 308 and the external optical fiber.

[0065] The device BGA high-frequency packaging substrate 307 and the chip, and the chip and the chip are electrically connected through gold wire bonding. Since the device BGA high-frequency packaging substrate 307 and the module / system motherboard are interconnected through the BGA interface, all the glue inside the device needs to be able to pass the high-temperature reflow soldering process, including the patch silver glue, coupling glue and refractive index matching glue.

[0066] In this embodiment, the material of the device BGA high-frequency packaging substrate 307 is Panasonic M7 resin, the high-frequency pad bandwidth is greater than 70Ghz, the 200G MZ driver chip 303 outputs a maximum voltage swing of 3Vpp, the 200G TIA chip 304 has a transimpedance gain of 4500Ω, the thermistor 302 has a resistance of 10KΩ, a resistance accuracy of ±3%, a coupling loss of 1.7dB between the single-mode optical fiber 308 and the COM waveguide 1313, and a gold wire bonding high-speed signal gold wire control length of 160μm to obtain optimal high-frequency performance.

[0067] The working process of 800G single-fiber bidirectional silicon optical devices is as follows: (1) The module / system mainboard supplies power to the devices (the four TX CW Laser light source chips 101-104 are lit, the TEC thermoelectric controller 301 is powered and the thermistor 302 is monitored for resistance, and PID temperature control is started, the 4×200G MZ driver chip 303 is powered, the 4×200G TIA chip 304 is powered, and the silicon photonic working point control IC chip 305 is powered), and communicates with the silicon photonic working point control IC chip 305.

[0068] (2) Confirm that the optical power and wavelength of the external optical signal are stable, and connect the external optical signal to the device through the single-mode optical fiber 308.

[0069] (3) The silicon photonic working point control IC chip 305 automatically searches for the working point of the silicon photonic heating resistor, and after the working point is successfully configured, it is fed back to the module / system mainboard.

[0070] The module / system mainboard is loaded with 4×200Gbps high-frequency signals for 800G signal transmission.

[0071] Since the 800G single-fiber bidirectional silicon photonic chip 21 has four MZM modulators and eight MR microring resonators that need to control the operating point (polarization voltage of the heating resistor), it needs to occupy the client module / system motherboard MCU resources. We have integrated the 305_silicon photonic operating point control IC in the device to control the operating points of the four MZM modulators and eight MR microring resonators, a total of 12 heating resistors.

[0072] The silicon photonic chip operating point voltage control process is divided into the following steps: S1, scan the TXMR heating resistor 1602 in the fourth transmitter channel RX4 to confirm that no light enters the TXMR in the fourth channel; Specifically: scan the voltage of the fourth TXMR heating resistor 1602 (the four TXMR heating resistors are marked with reference numerals: 165, 166, 167, 168), monitor the current of the fourth corresponding MZM-MPD backlight detector 11 (the four MZM-MPD backlight detectors are marked with reference numerals: 111, 112, 113, 114), and plot the voltage of each TXMR heating resistor 1602 and the current of the corresponding MZM-MPD backlight detector 11. Set the voltage of the TXMR heating resistor 1602 to the voltage of the TXMR heating resistor 1602 corresponding to the maximum current point of the corresponding MZM-MPD backlight detector 11, and confirm that no light enters the transmitter microring resonator (TXMR) 1401 at this time.

[0073] S2. Set the working point of the fourth MZM heating resistor 1601: Specifically: scan the voltage of the fourth MZM heating resistor 1601 (the reference numerals of the four MZM heating resistors are: 161, 162, 163, 164 respectively), monitor the current of the fourth corresponding MZM-MPD backlight detector 11, and draw a curve of the voltage of each MZM heating resistor 1601 and the current of the corresponding MZM-MPD backlight detector 11.

[0074] The voltage of the MZM heating resistor 1601 is set to the voltage of the MZM heating resistor 1601 corresponding to the 3 dB operating point of the MZM modulator, thereby completing the setting of the operating point of the MZM heating resistor 1601 .

[0075] S3. Set the operating point threshold and operating point of the fourth TXMR heating resistor 1602: Specifically: Scan the voltage of the fourth TXMR heating resistor 1602 respectively, monitor the current of the fourth corresponding MZM-MPD backlight detector 11, and draw a curve of the voltage of each TXMR heating resistor 1602 and the current of the corresponding MZM-MPD backlight detector 11. Find the minimum point of the photocurrent of the MZM-MPD backlight detector 11 (at this time, all the light output of the MZM modulator is coupled into the TXMR) and the maximum point of the photocurrent.

[0076] Set the voltage of the TXMR heating resistor 1602 to the voltage of the TXMR heating resistor 1602 corresponding to the minimum current point of the MZM-MPD backlight detector 11, and complete the setting of the working point of the TXMR heating resistor 1602; set the voltage of the TXMR heating resistor 1602 to the voltage of the TXMR heating resistor 1602 corresponding to 5% of the maximum photocurrent point of the MZM-MPD backlight detector 11, and complete the setting of the working point threshold of the TXMR heating resistor 1602.

[0077] In actual work, the working point will shift. As long as the current of the MZM-MPD backlight detector 11 is lower than the working point threshold, it is considered that the voltage of the TXMR heating resistor 1602 is in a normal working state (the light output of the MZM modulator is coupled into the TXMR with a higher efficiency); when it is monitored that the current of the MZM-MPD backlight detector 11 is higher than the working point threshold, the TXMR heating resistor voltage is automatically adjusted to return to a state below the threshold.

[0078] S4, scanning the RXMR heating resistor 1603 of the fourth receiver to confirm that no light enters the receiver microring resonator (RXMR) 1402 of the channels of the fourth receiver; Specifically: scan the voltage of the RXMR heating resistor 1603 of the fourth receiver (the reference numerals of the four RXMR heating resistors are: 169, 1610, 1611, 1612, respectively), monitor the photocurrent curve of the fourth single-wave 200G PD12 (the reference numerals of the four single-wave 200G PDs are: 121, 122, 123, 124, respectively), set the voltage of the RXMR heating resistor 1603 to the minimum current point of the single-wave 200G PD12, and confirm that no light enters the receiver microring resonator 1402 at this time.

[0079] S5. Set the operating point threshold and operating point of the fourth RXMR heating resistor 1603: Specifically, the voltage of the fourth MR heating resistor 1603 is scanned, and the photocurrent curve of the fourth single-wave 200G PD12 is monitored respectively to find the maximum point of the photocurrent of the 124 high-speed PD (at this time, all the incoming light of the COM waveguide is coupled into the 148 RXMR).

[0080] Set the voltage of the MR heating resistor 1603 to the voltage of the MR heating resistor 1603 corresponding to 95% of the maximum photocurrent point of the single-wave 200G PD 12, and complete the setting of the working point threshold of the RXMR heating resistor 1603; set the voltage of the MR heating resistor 1603 to the voltage of the MR heating resistor 1603 corresponding to the maximum photocurrent point of the single-wave 200G PD 12, and complete the setting of the working point of the RXMR heating resistor 1603.

[0081] In actual operation, the working point will shift; as long as the single-wave 200G PD 12 photocurrent is higher than the working point threshold, it is considered that the voltage of the RXMR heating resistor 1602 is in a normal working state (the COM waveguide light is coupled into the RXMR with high efficiency); when it is monitored that the single-wave 200G PD 12 photocurrent is lower than the working point threshold, the voltage of the RXMR heating resistor 1602 is automatically adjusted to return to a state higher than the working point threshold.

[0082] S6, repeating steps S1 to S5, scanning the MR heating resistors of the third transmitter channel RX3, the second transmitter channel RX2, and the first transmitter channel RX1 in sequence, formulating the operating point threshold, and setting the operating point; Set the RX MR heating resistor operating points in the order of channels 4, 3, 2, and 1. Since the light entering the COM end will enter RX4, RX3, RX2, and RX1 in turn, the order of setting the operating points cannot be disrupted.

[0083] S7. The operating point voltages of the 12 heating resistors on the silicon photonic chip are all set, and the feedback completion signal is given to the module / system mainboard.

[0084] In the embodiment, it takes 2291ms from the power-on of the module to the completion of the debugging of the working points of the 12 heating resistors on the silicon photonic chip and the device entering the normal working state. The three temperature points of the commercial grade ambient temperature (0℃, 25℃, 70℃) were tested. During the temperature rise and fall process, the 3dB working point drift of the four heating resistors was less than 0.3dB, and the current values ​​of the eight micro-switch MR heating resistors were all within the threshold range without deviation.

[0085] The working process of 800G single-fiber bidirectional silicon optical devices is as follows: (1) The module / system mainboard supplies power to the devices (101-104 four TX CW Laser light source chips are lit, 301_TEC power supply and 302_thermistor resistance monitoring and PID temperature control are started, 303_4×200G MZ driver chip power supply, 304_4×200G TIA power supply, 305_silicon photonic working point control IC power supply), and communicates with 305_silicon photonic working point control IC.

[0086] (2) Confirm that the optical power and wavelength of the external optical signal are stable, and connect the external optical signal to the device through a 308mm single-mode optical fiber.

[0087] (3) 305_Silicon photonic working point control IC automatically searches for the working point of the silicon photonic heating resistor, and feedback is given to the module / system mainboard after the working point configuration is successful.

[0088] The module / system mainboard is loaded with 4×200Gbps high-frequency signals for 800G signal transmission.

[0089] Fig.11 It is a flow chart of the device operating point control method.

[0090] The innovation of the present invention is: The photonic integrated circuit (PIC) built using a single-wavelength 200G modulator, detector and thermally tunable micro-ring resonator realizes the chip's single-fiber bidirectional 800G optical signal transmission function by hybridizing a flip-chip external laser into the PIC to provide a light source.

[0091] A BGA silicon photonic device was designed. Through the internal packaging of a thermoelectric controller (TEC) and a silicon photonic operating point control IC with integrated ADC / DAC, the thermoelectric controller (TEC) makes the wavelength of the laser more stable and the three-temperature performance of the microring resonator more stable. The silicon photonic operating point control IC can quickly complete the debugging of the bias voltage operating points of the 12 heating resistors and perform real-time control after the device is powered on, reducing the device's dependence on the client MCU control resources.

[0092] The working point control method and process of 800G single-fiber bidirectional silicon photonic devices are given, which can quickly and stably control the working point of the silicon photonic chip, so that the chip can work with high reliability for a long time.

[0093] In the description of the embodiments of the present application, it should be noted that in the description of the present application, terms such as "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description, and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present application.

[0094] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0095] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An 800G single-fiber bidirectional silicon photonic chip, characterized in that: The invention comprises four transmitters with different single-wavelengths of 200G and four receivers with different single-wavelengths of 200G integrated inside a silicon photonic chip (21), wherein the optical signals of the transmitters and the receivers are coupled via a micro-ring resonator and a chip I / O COM waveguide (1313), and the chip I / O COM waveguide (1313) transmits a single-fiber bidirectional 800G optical signal to the outside via an external optical fiber.

2. The 800G single-fiber bidirectional silicon photonic chip according to claim 1, characterized in that: Each of the transmitters comprises a CW Laser light source chip (20) and a transmitter micro-ring resonator (1401); The CW laser light source chip (20) is electrically connected to a pad on one side of a CW laser coupling step (17) of a silicon photonic chip (21); the waveguide of the CW laser light source chip (20) is sub-micron-coupled with a light source light inlet waveguide (1301); the light source light inlet waveguide (1301) is input to a single-wave 200G MZM modulator (15); and the MZM modulator (15) is output to an MZM output waveguide (1302); According to whether the resonance wavelength of the transmitter microring resonator (1401) matches the light output wavelength of the CW Laser light source chip (20), the optical signal of the MZM output waveguide (1302) enters the chip I / O COM waveguide (1313) for output or enters the MZM-MPD backlight detector (11).

3. The 800G single-fiber bidirectional silicon photonic chip according to claim 2, characterized in that: The end faces of the CW Laser light source chip (20) waveguide and the light source light inlet waveguide (1301) relative to the silicon photonic chip (21) are both inclined surfaces.

4. The 800G single-fiber bidirectional silicon photonic chip according to claim 2, characterized in that: The MZM modulator (15) is provided with an MZM heating resistor (1601) for adjusting the phase difference between two arms of the MZM modulator (15).

5. The 800G single-fiber bidirectional silicon photonic chip according to claim 2, characterized in that: The transmitter micro-ring resonator (1401) is provided with a TXMR heating resistor (1602) for adjusting the resonant wavelength of the transmitter micro-ring resonator (1401).

6. The 800G single-fiber bidirectional silicon photonic chip according to claim 1, characterized in that: Each of the receivers comprises a receiver micro-ring resonator (1402) and a single-wave 200G PD (12), the receiver micro-ring resonator (1402) outputs to the RXMR downlink output waveguide (1303), and the input optical signal of the external optical fiber is input to the chip I / O COM waveguide (1313); According to whether the resonance wavelength of the receiver microring resonator (1402) matches a wavelength of an input optical signal, the receiver microring resonator (1402) is coupled and output to a single-wavelength 200G PD (12) through an RXMR downlink output waveguide (1303).

7. The 800G single-fiber bidirectional silicon photonic chip according to claim 6, characterized in that: The receiver micro-ring resonator (1402) is provided with an RXMR heating resistor (1603) for adjusting the resonant wavelength of the receiver micro-ring resonator (1402).

8. The 800G single-fiber bidirectional silicon photonic chip according to claim 1, characterized in that: The CW laser light source chip (20) comprises a CW laser InP substrate (201), a CW laser active region waveguide (202), a CW laser electrode (203), and a CW laser electrode pre-solder (204) which are stacked in sequence; The silicon photonic chip (21) comprises a silicon waveguide cladding (211), a silicon waveguide (212), a silicon dioxide layer (213), a silicon substrate (214), and a silicon photonic chip electrode (215); the silicon waveguide cladding (211), the silicon waveguide (212), and the silicon dioxide layer (213) are sequentially stacked up and down and arranged above one side of the silicon substrate (214); and the silicon photonic chip electrode (215) is arranged above the other side of the silicon substrate (214); The silicon photonic chip electrode (215) and the CW laser electrode (203) are electrically connected.

9. A device based on the 800G single-fiber bidirectional silicon photonic chip according to any one of claims 1 to 7, characterized in that: It includes a device BGA high-frequency packaging substrate (307), a TEC thermoelectric controller (301) for controlling the temperature of a silicon photonic chip (21), four 200G MZ driver chips (303) for amplifying a single-wave 200G electrical signal input to a module / system mainboard and then loading it on an MZM, four 200G TIA chips (304) for amplifying a single-wave 200G electrical signal for high-speed PD output and then outputting it to the module / system mainboard, a silicon photonic operating point control IC chip (305) for sampling MPD and PD photocurrents and controlling 12 heating resistors on the adjustment chip to make them work at an optimal bias voltage position, and a single-channel FA (306); The TEC thermoelectric controller (301) is mounted with a silicon photonic chip (21) and a thermistor (302); the four 200G MZ driver chips (303), the four 200G TIA chips (304) and the silicon photonic operating point control IC chip (305) are all mounted on a device BGA high-frequency packaging substrate (307); and the single-channel FA (306) is coupled with the chip I / O COM waveguide (1313) and fixed on the TEC thermoelectric controller (301).

10. A method for controlling the operating point voltage of an 800G single-fiber bidirectional silicon photonic chip according to any one of claims 1 to 8, comprising the following steps: Step 1, respectively scan the voltages of the TXMR heating resistors (1602) of the four transmitters, monitor the current curves of the four corresponding MZM-MPD backlight detectors (11), set the voltage of the TXMR heating resistor (1602) to the maximum current point of the MZM-MPD backlight detector (11), confirm that no light enters the transmitter microring resonator (1401) at this time, and proceed to the next step; Step 2: Set the working points of the four MZM heating resistors (1601): Scanning the voltages of the MZM heating resistors (1601) of the four transmitters respectively, monitoring the voltage curves of the four MZM-MPD backlight detectors (11), and setting the operating point voltage of the MZM heating resistor (1601) to the 3 dB operating point of the MZM modulator (15); Step 3: Set the operating point thresholds and operating points of the four TXMR heating resistors (1602): Scan the voltages of the TXMR heating resistors (1602) of the four transmitters respectively, monitor the current curves of the four MZM-MPD backlight detectors (11), set the operating point threshold voltage of the TXMR heating resistor (1602) to an operating point of 5% of the maximum photocurrent point of the MZM-MPD backlight detector (11), and set the operating point voltage of the TXMR heating resistor (1602) to an operating point of the minimum current point of the MZM-MPD backlight detector (11); Step 4: Scan the voltages of the RXMR heating resistors (1603) of the four receivers respectively, monitor the photocurrent curves of the four single-wave 200G PDs (12), set the voltage of the RXMR heating resistor (1603) to the minimum current point of the single-wave 200G PD (12), confirm that no light enters the receiver microring resonator (1402) at this time, and proceed to the next step; Step 5. Set the operating point threshold and operating point of the four RXMR heating resistors (1603): Scan the voltages of four RXMR heating resistors (1603) respectively, monitor the photocurrent curves of four single-wave 200G PDs (12), use 95% of the maximum photocurrent point of the single-wave 200G PD (12) as the resonance point threshold of the receiver microring resonator (1402), and set the voltage to the maximum photocurrent point of the single-wave 200G PD (12); Step 6: Feedback the 12 operating point threshold voltages and operating point voltages on the silicon photonic chip (21) to the module / system mainboard.

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