A tuning system for a micro-ring modulator

Abstract

The application discloses a kind of micro-ring modulator's tuning system, including substrate, bus waveguide and micro-ring waveguide formed in the top layer silicon of substrate;The micro-ring waveguide is divided into capacitive tuning area, modulation area and its surrounding thermal resistance tuning area along circumference;The thermal resistance tuning area is powered to generate Joule heat to increase waveguide temperature, so that modulation area resonance wavelength occurs red shift, and constitutes coarse tuning unit;The capacitive tuning area is reduced waveguide refractive index by plasmonic dispersion effect when applying forward bias, so that modulation area resonance wavelength occurs blue shift, and constitutes fine tuning unit;The modulation area is used to load radio frequency signal to realize electro-optic modulation;It further includes control unit, and is electrically connected respectively with the coarse tuning unit and fine tuning unit;The control unit is configured to perform vernier caliper type hierarchical tuning method to tune modulation area, so that the resonance wavelength of modulation area reaches target working wavelength.The application combines thermal tuning and electrical coordination, and realizes complementary advantages of both.

Description

Technical Field

[0001] This invention belongs to the field of micro-ring modulator technology, and particularly relates to a tuning system for a micro-ring modulator. Background Technology

[0002] Silicon-based microring modulators are small in size, low in power consumption, compatible with CMOS processes, and easy to integrate on a large scale. However, due to factors such as semiconductor manufacturing process deviations, ambient temperature fluctuations, and device aging drift, the inherent resonant wavelength of the microring resonator is prone to deviating from the preset target operating wavelength, leading to a decrease in extinction ratio, an increase in insertion loss, and a deterioration in modulation performance. Therefore, a stable and reliable resonant wavelength tuning mechanism must be provided to ensure the normal operation of the microring modulator.

[0003] Current microring resonator wavelength tuning technology is mainly divided into two categories: thermo-optical tuning and carrier dispersive electrical tuning.

[0004] Thermo-optical tuning relies on the thermo-optical effect of silicon materials. By changing the refractive index of the waveguide through the heating unit, the resonant wavelength is red-shifted towards longer wavelengths. It has the advantage of a large tuning range, which can usually cover a wavelength range of several nanometers. However, the thermal response speed is slow, generally ranging from microseconds to milliseconds, and the power consumption is relatively high. In multi-channel high-density integration scenarios, it is easy to cause thermal crosstalk between channels.

[0005] Carrier dispersive electrical tuning, typically represented by capacitor tuning structures, blue-shifts the resonant wavelength toward shorter wavelengths by changing the carrier concentration in the waveguide. It features fast tuning speed and high control precision, but the tuning range is very limited, usually only in the sub-nanometer range, making it difficult to cover large wavelength shifts caused by process deviations on its own.

[0006] International patent application WO2018068507A1 discloses a control method and apparatus for a microring resonator. The control method includes: after receiving a wavelength configuration command, using the nearest resonant wavelength as a reference, calculating the target driving power of the hot electrode according to the driving power step value corresponding to the channel spacing, and realizing the coarse adjustment of the resonant wavelength through step-type thermal tuning; after the coarse adjustment is completed, the hot electrode is fine-tuned with a smaller power step size to maintain the locked state of the resonant wavelength.

[0007] This solution improves the control efficiency of thermal tuning to some extent through a hierarchical step control method. However, since it uses a single thermal tuning unit to achieve hierarchical control, tuning speed and tuning accuracy cannot be simultaneously achieved. On the other hand, if thermal tuning is used throughout the entire process in high-temperature, long-term operating scenarios, it will exacerbate heat accumulation in the chip, resulting in increased overall system power consumption and decreased long-term operational reliability. Summary of the Invention

[0008] The purpose of this invention is to provide a tuning system for a micro-ring modulator that partially solves or alleviates at least one of the above-mentioned shortcomings in the prior art. Depending on different operating conditions, it combines thermal tuning and electrical coordination for synergistic tuning, making full use of the complementary advantages of the two, thereby achieving a certain degree of balance between tuning speed and tuning accuracy.

[0009] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution: A first aspect of the present invention is to provide a tuning system for a microring modulator, comprising a substrate, a bus waveguide and a microring waveguide formed on the top silicon layer of the substrate, the bus waveguide having an input port and an output port, and the microring waveguide and the bus waveguide being coupled by an evanescent wave. The micro-ring waveguide is divided into a capacitor tuning region and a modulation region along the circumference; and a thermal resistance tuning region is provided on its outer side. The thermal resistance tuning region is energized to generate Joule heating, which raises the waveguide temperature and causes the resonant wavelength of the modulation region to redshift, thus forming a coarse tuning unit. When a forward bias voltage is applied, the capacitor tuning region reduces the waveguide refractive index through the plasma dispersion effect, causing a blue shift in the resonant wavelength of the modulation region, thus forming a fine tuning unit. The modulation region is used to load radio frequency signals to achieve electro-optic modulation; It also includes a control unit, which is electrically connected to the coarse tuning unit and the fine tuning unit respectively; the control unit is configured to perform a vernier caliper-type graded tuning method to tune the modulation region so that the resonant wavelength of the modulation region reaches the target operating wavelength.

[0010] Furthermore, the coarse tuning unit also includes a heating resistor structure acting in the thermal resistor tuning region and a first electrode group connected to the heating resistor structure; the heating resistor structure is a doped silicon resistor or a deposited titanium nitride thin film resistor, and the first electrode group includes a first tuning electrode and a second tuning electrode respectively electrically connected to both ends of the heating resistor.

[0011] Furthermore, the fine tuning unit also includes a MOS capacitor doped structure and a second electrode group connected to the MOS capacitor doped structure; the MOS capacitor doped structure is a lateral MOS capacitor structure, which forms a carrier accumulation layer at the waveguide interface under forward bias to change the effective refractive index of the waveguide.

[0012] Furthermore, the modulation region is provided with a PN junction structure and a third electrode group connected to the PN junction structure; the PN junction operates in a reverse bias state, and the third electrode group includes differential radio frequency electrodes.

[0013] Furthermore, the control unit includes two digital-to-analog conversion modules, one of which is a coarse-tuning digital-to-analog conversion module electrically connected to the thermal resistance tuning area, and the other is a fine-tuning digital-to-analog conversion module electrically connected to the capacitor tuning area.

[0014] Furthermore, the control unit specifically includes: The wavelength deviation acquisition subunit is configured to acquire the wavelength deviation between the initial resonant wavelength of the micro-ring modulator and the target operating wavelength, wherein the wavelength deviation is the difference between the target operating wavelength and the initial resonant wavelength. The judgment subunit is configured to determine whether the wavelength deviation is greater than or equal to a first wavelength threshold. The first tuning subunit is configured to, when the wavelength deviation is greater than or equal to a first wavelength threshold, determine the target thermal tuning amplitude and the target electrical tuning amplitude of the micro-ring modulator based on the wavelength deviation, wherein the target thermal tuning amplitude is the red shift generated by thermal tuning and the target electrical tuning amplitude is the blue shift generated by electrical tuning; and to activate the coarse tuning unit to perform thermal tuning until the target thermal tuning amplitude is reached, and then activate the fine tuning unit to perform electrical tuning until the target electrical tuning amplitude is reached, thereby adjusting the resonant wavelength of the micro-ring modulator to the target operating wavelength; The second tuning subunit is configured to set the target thermal tuning amplitude to 0 when the wavelength deviation is less than the first wavelength threshold, determine the target electrical tuning amplitude of the micro-ring modulator based on the wavelength deviation, the target electrical tuning amplitude being the blue shift generated by electrical tuning; and initiate the fine tuning unit to perform electrical tuning until the target electrical tuning amplitude is reached, thereby adjusting the resonant wavelength of the micro-ring modulator to the target operating wavelength.

[0015] Furthermore, the first tuning subunit is also configured to: compare the wavelength deviation with a second wavelength threshold, wherein the second wavelength threshold is greater than the first wavelength threshold; if the wavelength deviation is greater than or equal to the second wavelength threshold, it is determined to be a large deviation condition, and the first thermoelectric synergy parameter is calculated; if the wavelength deviation is greater than or equal to the first wavelength threshold and less than the second wavelength threshold, it is determined to be a medium deviation condition, the current chip temperature or the current ambient temperature is obtained, the current chip temperature or the current ambient temperature is compared with a preset temperature threshold, and a tuning scheme is selected based on the comparison result.

[0016] Furthermore, when a large deviation operating condition is determined, the first tuning subunit is specifically configured to calculate the first thermoelectric synergy parameter using the following formula: λ1 = C, Calculate λ2 = λ1 - λ0; Where λ0 is the wavelength deviation, λ1 is the target thermal tuning amplitude, λ2 is the target electrical tuning amplitude, and C is the preset fixed thermal tuning amplitude. The value of C is 30% to 50% of the maximum tuning range of the coarse tuning unit, and satisfies C - λ0 ≤ the maximum tuning range of the fine tuning unit.

[0017] Furthermore, the first tuning subunit is specifically configured to calculate the second thermoelectric synergy parameter using the following formula when the ambient temperature or chip temperature is determined to be less than a preset temperature threshold under moderate deviation conditions: λ1 = N × Q, λ2 = λ1 - λ0; Calculate; where λ0 is the wavelength deviation, λ1 is the target thermal tuning amplitude, λ2 is the target electrical tuning amplitude, Q is the tuning step size of the coarse tuning unit, and N is the number of tuning steps of the coarse tuning unit.

[0018] Furthermore, the first tuning subunit is specifically configured to: obtain the maximum effective blue-shift tuning range of the fine-tuning unit and the maximum red-shift tuning range under full-scale drive of the coarse-tuning unit; calculate the physical boundary constraints of the tuning step size Q using the maximum effective blue-shift tuning range and the maximum red-shift tuning range; construct a total cost function that simultaneously includes tuning speed cost and ESC margin cost, and solve it to obtain a preliminary optimal Q value; and correct the preliminary optimal Q value using the physical boundary constraints to obtain the final Q value.

[0019] Beneficial effects: The tuning system provided by this invention employs a thermal resistance tuning region as a coarse tuning unit, which can cover the full-range resonant wavelength drift corresponding to temperature fluctuations of tens of degrees Celsius, effectively offsetting wavelength shifts caused by chip process deviations and significant changes in ambient temperature. It uses a capacitor tuning region as a fine tuning unit, achieving sub-nanometer-level wavelength adjustment resolution, ensuring precise alignment of the resonant wavelength with the target operating wavelength. Compared to thermal tuning, it offers faster tuning speed, i.e., a faster response time. Both components work collaboratively in a caliper-like hierarchical architecture, significantly improving tuning resolution without compressing the effective tuning range, thus solving the problem of the inability to simultaneously achieve both tuning range and adjustment accuracy in traditional single-tuning schemes.

[0020] By employing a two-stage, coarse-tuning and fine-tuning approach to digital-to-analog converter (DAC) modules, the tuning effect of a single high-bit-width DAC can be achieved using two low-bit-width DAC chips. This eliminates the need for high-precision, high-cost DAC devices, directly reducing the material cost of the control circuit. Furthermore, the hierarchical tuning control logic is clearly layered: coarse-tuning handles wavelength range positioning, while fine-tuning ensures precise target point locking. The control algorithm is relatively simple to implement, reducing the development complexity of the control circuit and firmware, and facilitating mass deployment and debugging in large-scale silicon photonic interconnect systems.

[0021] Thermocouple tuning causes a redshift in the resonant wavelength, while capacitor tuning causes a blueshift. These two adjustments are in opposite directions, together forming a complete bidirectional wavelength adjustment capability. Compared to single-tuning schemes that can only achieve unidirectional wavelength shift, this invention can directly and quickly respond to both positive and negative wavelength drift. The closed-loop locking process does not rely on overshoot correction, resulting in faster wavelength locking speed and higher locking accuracy. It is better suited to the frequent and irregular temperature fluctuations in co-packaged optical scenarios, improving the reliability of long-term wavelength locking.

[0022] The micro-ring waveguide is circumferentially divided into a modulation region, a capacitance tuning region, and a thermal resistance tuning region. These functional regions are physically isolated from each other via intrinsic silicon waveguide segments. The high-speed electro-optic modulation function and the static wavelength tuning function are independent and do not interfere with each other. Tuning operations do not negatively affect the signal quality of the high-speed electro-optic modulation. The overall device structure is designed and fabricated based on standard SOI silicon photonics processes. Waveguide etching, ion doping, and metal electrode deposition are all compatible with mainstream commercial silicon photonics processes, requiring no additional special process steps. This results in excellent mass production adaptability and high process yield, and ensures greater stability and reliability during long-term device operation.

[0023] The vernier caliper-style graded tuning method provided by this invention sets a first wavelength threshold and a second wavelength threshold, classifying wavelength deviation into three categories: small deviation, medium deviation, and large deviation, and matching corresponding tuning modes: For the small deviation condition, a pure electrical tuning scheme is used, with no additional heat dissipation and the fastest response speed; for the large deviation condition, a combination of fixed thermal tuning amplitude and electrical tuning is used. Due to the fast calculation mode with a fixed thermal tuning amplitude, it eliminates the need for iterative stepping, significantly shortening the parameter calculation and tuning time during the initial power-on calibration of the chip, achieving rapid wavelength locking; for the medium deviation condition, a standard vernier step tuning mode is used, with fixed-gradient coarse tuning combined with electrical fine tuning to ensure tuning accuracy and consistency. In other words, in cases of large deviation, priority is given to ensuring the reliability and speed of wavelength locking, thereby quickly achieving wavelength locking and avoiding communication interruptions or calculation errors; while in cases of medium deviation, tuning accuracy is guaranteed to a limited extent. The grading strategy proposed in this application can adaptively match different application scenarios such as initial calibration and temperature drift compensation during operation, and achieve the optimal balance between tuning efficiency and tuning performance within the entire deviation range.

[0024] This invention proposes a weighted cost function based on tuning speed cost and ESC margin cost, obtaining the theoretically optimal step size through analytical differentiation, replacing the traditional empirical value selection method. Simultaneously, it uses the maximum range of the ESC after deducting the steady-state margin as the upper limit constraint and the minimum step size corresponding to the hardware resolution of the digital-to-analog converter as the lower limit constraint to perform boundary correction on the theoretically optimal value. This ensures that tuning has no blind spots and that hardware implementation is feasible. Furthermore, by adjusting the weighting coefficients, it flexibly adapts to different performance requirements such as speed-first, balanced mode, and margin-first modes, giving the step size design a clear quantitative basis and scenario adaptability, effectively improving the overall performance of the tuning system.

[0025] This invention introduces a dual-dimensional judgment dimension of chip temperature or ambient temperature and continuous operating time to form an adaptive collaborative tuning mode. Under high-temperature, short-duration operating conditions, a basic thermal tuning amplitude is used for thermoelectric collaborative tuning, balancing tuning range and accuracy. Under high-temperature, long-duration operating conditions, the thermal tuning amplitude is appropriately reduced to decrease the heat generated by thermal tuning, thereby reducing the risk of localized heat accumulation within the chip due to prolonged thermal tuning and reducing inter-channel thermal crosstalk. This results in lower thermal power consumption at a lower performance cost, suppressing the risk of thermal failure. This mechanism significantly improves the long-term operational reliability of high-density photonic integrated chips in high-temperature environments, and is particularly suitable for high-integration, high-heat-density applications such as co-packaged optics. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] Figure 2 This is a flowchart of the present invention.

[0029] Summary of attached labeling and identification: 100 - Silicon device layer, 101 - Input port, 102 - Output port, 103 - Micro-ring waveguide, 104 - First doped region, 105 - Second doped region, 106 - Third doped region, 107 - Fourth doped region, 108 - Thermocouple tuning region, 110-1 - First differential RF electrode, 110-2 - Second differential RF electrode, 111-1 - First metal electrode, 111-2 - Second metal electrode, 112-1 - First tuning electrode, 112-2 - Second tuning electrode. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] In this document, suffixes such as "module," "part," or "unit" used to denote elements are used only for the purpose of illustrative purposes and have no specific meaning in themselves. Therefore, "module," "part," or "unit" may be used interchangeably.

[0032] In this document, the terms "upper," "lower," "inner," "outer," "front," "rear," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In this document, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0035] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0036] Example 1: like Figure 1As shown, this embodiment provides a tuning system for a micro-ring modulator, fabricated on a silicon-on-insulator (SOI) substrate. The substrate, from bottom to top, comprises a bottom silicon support substrate, a silicon dioxide buried oxide layer, and a top silicon device layer 100. All optical waveguide structures of the device are formed within the top silicon layer through photolithography, etching, and doping processes. The top silicon layer uses standard thickness parameters for commercial silicon photonics processes, such as 220 nm, to ensure compatibility with mainstream silicon photonics wafer fabrication lines without requiring additional special processes.

[0037] A bus waveguide and a micro-ring waveguide are formed in the top silicon layer. The bus waveguide is a straight strip waveguide, with its two ends forming an input port 101 and an output port 102, respectively, for carrying the input transmission and output acquisition of optical waves. The micro-ring waveguide is a closed ring waveguide structure, adjacent to one side of the bus waveguide. The sidewalls of the micro-ring waveguide and the sidewalls of the bus waveguide maintain a set coupling distance, and the two achieve optical energy coupling interaction through the evanescent wave effect.

[0038] During operation, the incident light signal enters the bus waveguide from the input port 101. When it is transmitted to the coupling region, some of the light energy is coupled into the micro-ring waveguide and circulates along the ring path. Wavelengths that meet the micro-ring resonance condition will form resonance enhancement in the ring. Light signals that do not meet the resonance condition continue to propagate forward along the bus waveguide and are finally output from the output port 102.

[0039] The micro-ring waveguide is divided into two independent functional regions along its circumference: a capacitor tuning region and a modulation region. Furthermore, a thermal resistance tuning region 108 is provided on the outer side of the micro-ring waveguide. Adjacent functional regions are physically isolated by an intrinsic silicon waveguide segment to avoid crosstalk between the carrier distribution, electric field distribution, and thermal field distribution in different regions, ensuring that each functional region can be independently controlled and does not interfere with each other.

[0040] The modulation region is the area in the micro-ring modulator where high-speed electro-optic modulation is achieved. A PN junction structure is formed inside the waveguide in this region, with P-type and N-type doped regions respectively located on opposite sides of the waveguide, forming a lateral PN junction structure. For example, see [link to example]. Figure 1 The modulation region includes a third doped region 106 and a fourth doped region 107 with opposite doping types, thereby forming a PN junction in this region. For example, the third doped region 106 can be P-type doped, and the fourth doped region 108 can be N-type doped.

[0041] Furthermore, the modulation region 106 is provided with a third electrode group connected to the PN junction structure. The third electrode group includes a pair of differential radio frequency electrodes and a first differential radio frequency electrode 110-1 and a second differential radio frequency electrode 110-2. The two electrodes are electrically connected to the P-type doped region (such as the third doped region 106) and the N-type doped region (such as the fourth doped region 107) of the PN junction, respectively. During normal operation, the PN junction is in a reverse bias state. The external high-speed radio frequency electrical signal is loaded to both ends of the PN junction through the differential radio frequency electrodes. The effective refractive index of the waveguide is changed by the plasma dispersion effect, thereby performing phase modulation and intensity modulation on the optical signal transmitted in the micro-ring, completing the high-speed electro-optic signal conversion function.

[0042] The thermal resistance tuning region 108 constitutes the coarse tuning unit of the system, used to achieve a wide range of resonant wavelength adjustment. The thermal resistance tuning region 108 is provided with a heating resistor structure and a first electrode group connected to the heating resistor structure. The heating resistor structure can be implemented in two ways: one is to heavily dope the silicon material on both sides of the microring waveguide through ion implantation to form a low-resistance doped silicon resistor; the other is to deposit titanium nitride material on the top or side of the microring waveguide to form a thin film heating resistor.

[0043] The first electrode group includes a first tuning electrode 112-1 and a second tuning electrode 112-2, which are electrically connected to the two ends of the heating resistor structure, respectively. When a driving voltage is applied to the first electrode group, a current is generated inside the heating resistor structure, and heat is released through the Joule effect. The heat is transferred to the micro-ring waveguide through thermal conduction, causing the overall temperature of the waveguide to rise. Based on the thermo-optical effect of silicon material, the increase in waveguide temperature leads to an increase in its effective refractive index, ultimately causing the resonant wavelength of the micro-ring to shift towards longer wavelengths, i.e., a redshift occurs. The tuning range of the heating resistor tuning region 108 is wide, covering all wavelength shifts corresponding to temperature fluctuations of tens of degrees Celsius. It can cope with large-range wavelength shifts caused by process deviations and large changes in ambient temperature, and undertakes the functions of initial calibration and large-amplitude coarse adjustment.

[0044] The capacitor tuning region 104 constitutes the fine tuning unit of the system, used to achieve high-precision fine adjustment of the resonant wavelength. The capacitor tuning region 104 is provided with a MOS capacitor doped structure and a second electrode group connected to the MOS capacitor doped structure. The MOS capacitor doped structure is a lateral MOS capacitor structure, with a P-type doped region, an intrinsic silicon region, and an N-type doped region sequentially formed along the waveguide lateral direction, forming a laterally stacked capacitor structure. For example, see [link to example]. Figure 1 The capacitor tuning region includes a first doped region 104 and a second doped region 105 with opposite doping types, thus forming a capacitor tuning region. For example, the first doped region on the inner side of the ring waveguide is set as a P-type doped region, and the second doped region on the outer side is set as an N-type doped region.

[0045] Furthermore, the second electrode group includes a first metal electrode 111-1 and a second metal electrode 111-2, which are electrically connected to the P-type doped region (such as the first doped region 104) and the N-type doped region (such as the second doped region 105), respectively. When a forward bias voltage is applied to the second electrode group, an electron accumulation layer and a hole accumulation layer are formed at the interface between the intrinsic silicon region and the doped regions on both sides, respectively. The change in carrier concentration reduces the effective refractive index of the waveguide through the plasma dispersion effect, thereby causing the resonant wavelength of the microring to shift towards a shorter wavelength, i.e., a blue shift occurs. The capacitor tuning region 104 operates based on the carrier accumulation mechanism. In the steady-state wavelength-locked state that maintains a fixed bias voltage, there is almost no continuous conduction current inside the structure. Therefore, the static power consumption approaches zero, making it very suitable for precise wavelength maintenance and small-amplitude drift compensation under steady-state operation.

[0046] The system also includes a control unit. The output of the control unit is electrically connected to the first electrode group of the coarse tuning unit and the second electrode group of the fine tuning unit, respectively, to output a graded tuning control signal, execute the vernier caliper graded tuning method, and finally make the resonant wavelength of the modulation region 106 stably aligned with the target working wavelength.

[0047] The control unit contains two independent digital-to-analog converter (DAC) modules. One is a coarse-tuning DAC module, whose output is electrically connected to the first electrode group of the RTD tuning area 108, used to output an adjustable heating drive voltage to control the amplitude and rate of thermo-optical tuning. The other is a fine-tuning DAC module, whose output is electrically connected to the second electrode group of the capacitor tuning area 104, used to output an adjustable forward bias voltage to control the fine step size of electro-optical tuning. The two low-bit-width DAC modules work together, with the coarse-tuning module covering a wide wavelength range and the fine-tuning module covering high-precision adjustment steps. This hierarchical combination achieves the equivalent tuning effect of a single high-bit-width DAC module, eliminating the need for expensive high-precision DAC chips and effectively reducing hardware costs and the design complexity of the control circuit.

[0048] In some embodiments, the control unit is configured to perform a vernier caliper-type step-tuning method (see Embodiment 2 for details). Specifically, the control unit includes: The wavelength deviation acquisition subunit is configured to acquire the wavelength deviation between the initial resonant wavelength of the micro-ring modulator and the target operating wavelength, wherein the wavelength deviation is the difference between the target operating wavelength and the initial resonant wavelength. The judgment subunit is configured to determine whether the wavelength deviation is greater than or equal to a first wavelength threshold. The first tuning subunit is configured to, when the wavelength deviation is greater than or equal to a first wavelength threshold, determine the target thermal tuning amplitude and the target electrical tuning amplitude of the micro-ring modulator based on the wavelength deviation, wherein the target thermal tuning amplitude is the red shift generated by thermal tuning and the target electrical tuning amplitude is the blue shift generated by electrical tuning; and to activate the coarse tuning unit to perform thermal tuning until the target thermal tuning amplitude is reached, and then activate the fine tuning unit to perform electrical tuning until the target electrical tuning amplitude is reached, thereby adjusting the resonant wavelength of the micro-ring modulator to the target operating wavelength; The second tuning subunit is configured to, when the wavelength deviation is less than a first wavelength threshold, set the target thermal tuning amplitude to a preset amplitude, such as 0, determine the target electrical tuning amplitude of the micro-ring modulator based on the wavelength deviation, the target electrical tuning amplitude being the blue shift generated by electrical tuning; and initiate the fine tuning unit to perform electrical tuning until the target electrical tuning amplitude is reached, thereby adjusting the resonant wavelength of the micro-ring modulator to the target operating wavelength.

[0049] Preferably, the first tuning subunit is specifically configured to: compare the wavelength deviation with a second wavelength threshold, wherein the second wavelength threshold is greater than the first wavelength threshold; if the wavelength deviation is greater than or equal to the second wavelength threshold, it is determined to be a large deviation condition, and the first thermoelectric synergy parameter is calculated; if the wavelength deviation is greater than or equal to the first wavelength threshold and less than the second wavelength threshold, it is determined to be a medium deviation condition, the current chip temperature or the current ambient temperature is obtained, the chip temperature or the current ambient temperature is compared with a preset temperature threshold, and a tuning scheme is selected based on the comparison result.

[0050] When the condition is determined to be a large deviation, the formula for calculating the first thermoelectric synergy parameter by the first tuning subunit includes: λ1 = C, λ2 = λ1 - λ0. Where λ0 is the wavelength deviation, λ1 is the target thermal tuning amplitude, λ2 is the target electrical tuning amplitude, and C is the preset fixed thermal tuning amplitude. The value of C is 30% to 50% of the maximum tuning range of the coarse tuning unit, and satisfies C - λ0 ≤ the maximum tuning range of the fine tuning unit.

[0051] In some embodiments, when the ambient temperature or chip temperature is determined to be less than a preset temperature threshold under moderate deviation conditions, the formula for the first tuning subunit to calculate the second thermoelectric synergy parameter includes: λ1 = N×Q, λ2 = λ1 - λ0.

[0052] Where λ0 is the wavelength deviation, λ1 is the target thermal tuning amplitude, λ2 is the target electrical tuning amplitude, Q is the tuning step size of the coarse tuning unit, and N is the number of tuning steps of the coarse tuning unit.

[0053] Preferably, the step of the first tuning subunit specifically obtaining the tuning step size Q of the coarse tuning unit includes: obtaining the maximum effective blue-shift tuning range of the fine tuning unit and the maximum red-shift tuning range under full-scale drive of the coarse tuning unit; calculating the physical boundary constraints of the tuning step size Q using the maximum effective blue-shift tuning range and the maximum red-shift tuning range; constructing a total cost function that simultaneously includes tuning speed cost and ESC margin cost, and solving it to obtain a preliminary optimal Q value; and correcting the preliminary optimal Q value using the physical boundary constraints to obtain the final Q value. Specifically, see the Q value determination method in Embodiment 2.

[0054] Furthermore, the first tuning subunit is also configured to: when determined to be a medium deviation operating condition, and the detected current chip temperature or current ambient temperature is greater than or equal to a preset temperature threshold, further obtain the continuous operating time of the micro-ring modulator at the current target operating wavelength, compare the continuous operating time with a preset time period threshold, and select a tuning scheme based on the comparison result. If the continuous operating time of the micro-ring modulator at the target operating wavelength is less than the preset time period threshold, it indicates that the thermal tuning time of the micro-ring modulator is relatively short. Although the current chip temperature is high, the heat generated by the micro-ring modulator in a short time is still within the tolerable range, and the heat accumulation may not be serious. Therefore, thermoelectric synergistic tuning is adopted, and the second thermoelectric synergistic parameter calculation is performed. Vernier thermoelectric synergistic tuning is adopted to ensure tuning accuracy and range. If the continuous operating time is greater than or equal to the preset time threshold, it indicates that the chip is under prolonged high-temperature operation. Prolonged heating will further increase the chip temperature, significantly increasing the risk of thermal crosstalk between channels, and may even prevent the achievement of the expected thermal tuning effect. Therefore, the thermal tuning amplitude should be appropriately reduced to appropriately decrease heat source generation. Specifically, new thermoelectric synergy parameters (such as subsequent third thermoelectric synergy parameters) are calculated based on the same principle as the calculation method of the second thermoelectric synergy parameter. Preferably, the tuning amplitude is reduced by decreasing the tuning step size and / or the number of tuning steps in the second thermoelectric synergy parameter.

[0055] In some embodiments, the preset time period threshold is set according to the chip's thermal reliability index, typically ranging from tens of minutes to several hours; the chip temperature is collected in real time by an on-chip integrated temperature sensor.

[0056] In some embodiments, continuous operating time refers to the duration of continuous operation of the micro-ring modulator at the same target operating wavelength. During this continuous operating time, the micro-ring modulator may correspond to different computational subtasks, but all of these subtasks are based on the same target operating wavelength. Specifically, this continuous operating time is estimated in advance based on historical data statistical analysis of similar or identical large-scale model computation tasks when determining the tuning strategy for the current target operating wavelength. Because similar or identical large-scale model computation tasks employ similar tuning strategies, but these strategies may differ due to variations in the actual operating environment or conditions, the tuning strategies used by similar or identical large-scale model computation tasks cannot be directly and completely applied. However, the continuous operating time of the micro-ring modulator at the same target operating wavelength can be roughly estimated using historical data from similar or identical large-scale model computation tasks, and the target thermal tuning amplitude can be dynamically adjusted in conjunction with the current chip temperature or ambient temperature.

[0057] For example, a computational task involving a large model is typically divided into multiple computational subtasks executed by different photonic computing units. Data for some of these subtasks may be loaded onto the same target operating wavelength for transmission, and this target operating wavelength may be provided by the same microring modulator. Furthermore, the microring modulator may need to provide different target operating wavelengths at different computational stages. For instance, during the T1-T2 time period, a microring modulator utilizes an electrothermal co-tuning strategy to provide the target operating wavelength λ. 11 During the T2-T3 time period, the micro-ring modulator utilizes an electrothermal co-tuning strategy to provide the target operating wavelength λ. 12 The micro-ring modulator operates from the target operating wavelength λ. 11 Switch to the target operating wavelength λ 12 Previously (e.g., when approaching T2, or at the target operating wavelength λ) 11 For calculation subtasks that are about to end, it is necessary to first determine whether the time period T2-T3 is greater than or equal to the preset duration threshold. If the duration is less than the preset time threshold, that is, the continuous working time of the micro-ring modulator is not too long, even if the current chip temperature is high, the system can tolerate it because the continuous working time is not too long. Therefore, the second electrothermal coordination parameter is calculated to perform electrothermal coordination. If the duration is greater than or equal to a preset time threshold, it indicates that the current chip temperature is already relatively high. Since thermal tuning itself generates heat, a longer thermal tuning time may cause a significant further increase in chip temperature, thus exacerbating thermal crosstalk between channels and potentially failing to achieve the desired thermal coordination effect. Therefore, the thermal tuning duration should be appropriately reduced. Specifically, if the continuous operating time is greater than or equal to a preset time threshold, a third electrothermal coordination parameter calculation is performed to determine the target thermal tuning amplitude and the target electrical tuning amplitude of the micro-ring modulator. The calculation is performed as follows: λ1' = N' × Q', λ2' = λ1' - λ0, where λ1' is the target thermal tuning amplitude, λ2' is the target electrical tuning amplitude, Q' is the tuning step size of the heating tuning module, and N' is the number of tuning steps of the heating tuning module, and λ1' < λ1. For example, λ1' = N' × Q' = (N - N0) × Q, λ2' = λ1' - λ0; where N0 is the preset reduction tuning step size. Another example is λ1' = N' × Q' = N × (Q - Q0), λ2' = λ1' - λ0; where Q0 is the preset reduction step size. Of course, both the tuning step size and the number of tuning steps can be reduced simultaneously, with the ultimate goal of reducing λ1 to λ1'. Alternatively, a preset reduction amplitude can be directly set so that λ1 - preset amplitude reduction = λ1'. In other words, the focus of this application is not on how to reduce λ1 to λ1', but on using different electrothermal tuning coordination methods according to different ambient temperatures or chip temperatures. Example 2: like Figure 2 As shown, this embodiment provides a vernier caliper-type graded tuning method, deployed in the control unit of Embodiment 1, and its specific steps include: Step S100: Obtain the wavelength deviation.

[0058] In some embodiments, the current initial resonant wavelength of the micro-ring modulator and the preset target operating wavelength are first obtained, and the wavelength deviation between the two is calculated.

[0059] In this embodiment, the initial resonant wavelength can be obtained by scanning the transmission spectrum of the microring using the on-chip optical power monitoring unit to extract the wavelength value corresponding to the resonant valley; the target operating wavelength is the channel center wavelength preset by the wavelength division multiplexing system and is pre-stored in the chip's control register. The wavelength deviation is defined as the difference between the target operating wavelength and the initial resonant wavelength, i.e., wavelength deviation = target operating wavelength - initial resonant wavelength.

[0060] Step S200: Determine the wavelength deviation level.

[0061] In some embodiments, the calculated wavelength deviation λ0 is compared with a preset first wavelength threshold to determine the magnitude of the deviation and select the corresponding tuning scheme. The first wavelength threshold is equal to the maximum effective tuning range of the fine tuning unit. When the deviation is less than this threshold, in order to ensure the tuning accuracy and response speed, wavelength calibration can be completed by capacitor tuning alone, without the need to start thermal tuning. When the deviation is greater than or equal to this threshold, the range of capacitor tuning is insufficient to cover the deviation, and thermal tuning and electrical tuning must be started in tandem.

[0062] It is worth noting that when λ0 is negative, it means that the initial resonant wavelength is already greater than the target operating wavelength. In this case, tuning can only be completed by relying on the blue shift of the fine tuning unit.

[0063] If the wavelength deviation is greater than or equal to the first wavelength threshold, proceed to step S300 to execute the thermoelectric synergistic tuning process; if the wavelength deviation is less than the first wavelength threshold, proceed to step S400 to execute the pure electric tuning process.

[0064] Step S300, thermoelectric synergistic tuning process.

[0065] In some embodiments, when the wavelength deviation is greater than or equal to a first wavelength threshold, the target thermal tuning amplitude and the target electrical tuning amplitude of the micro-ring modulator are first determined according to the wavelength deviation, wherein the target thermal tuning amplitude is the red shift generated by thermal tuning and the target electrical tuning amplitude is the blue shift generated by electrical tuning; then the coarse tuning unit is started to perform thermal tuning until the target thermal tuning amplitude is reached, and then the fine tuning unit is started to perform electrical tuning until the target electrical tuning amplitude is reached, thereby adjusting the resonant wavelength of the micro-ring modulator to the target operating wavelength.

[0066] In this step, to further adapt to tuning requirements of different deviation levels and improve tuning efficiency and operating condition adaptability (i.e., improve system flexibility), the operating conditions of thermoelectric synergistic tuning are further subdivided. The specific process is as follows: S301. The wavelength deviation is compared with the second wavelength threshold, which is greater than the first wavelength threshold. The second wavelength threshold is set according to the typical distribution of chip process deviation, and is usually 3 to 5 times the first wavelength threshold.

[0067] S302. If the wavelength deviation is greater than or equal to the second wavelength threshold, it is usually a large wavelength shift caused by the initial calibration of the chip upon power-on or inherent process deviation. This is determined to be a large deviation condition, and the first thermoelectric synergy parameter calculation is performed.

[0068] Specifically, when a large deviation operating condition is determined, the first thermoelectric synergy parameter is calculated, and a rapid coarse adjustment strategy with a fixed thermal adjustment amplitude is adopted. The calculation formula is as follows: λ1 = C, λ2=λ1-λ0 Where λ0 is the wavelength deviation, λ1 is the target thermal tuning amplitude, i.e. the total red shift required for thermal tuning; λ2 is the target electrical tuning amplitude, i.e. the total blue shift required for capacitor tuning; and C is the preset fixed thermal tuning amplitude.

[0069] In this embodiment, the value of C is 30% to 50% of the maximum tuning range of the coarse tuning unit. This range allows the thermal tuning to operate in the linear range with optimal efficiency, while reserving sufficient upper and lower tuning margins. Furthermore, the value of C satisfies the constraint C - λ0 ≤ the maximum tuning range of the fine tuning unit, ensuring that the residual deviation caused by thermal tuning overtuning can be fully compensated by capacitor tuning, thus avoiding tuning failure.

[0070] For example, the maximum tuning range of the coarse tuning unit is 2nm, with C=0.8nm, accounting for 40% of the maximum tuning range. The maximum tuning range of the fine tuning unit is 0.3nm. If the current wavelength deviation λ0=0.65nm, the target thermal tuning amplitude λ1=0.8nm and the target electrical tuning amplitude λ2=0.8-0.65=0.15nm are calculated. Since 0.15nm is less than the maximum electrical tuning range of 0.3nm, the solution is feasible. In this mode, in scenarios with large deviations, there is no need for step-by-step calculations. The thermal tuning can be directly set to a fixed amplitude, which can significantly shorten the parameter calculation and tuning time, and achieve rapid wavelength locking upon power-on. That is, while ensuring a certain tuning accuracy, it also takes into account the coordination speed (or response speed).

[0071] S303 When the wavelength deviation is between the first wavelength threshold and the second wavelength threshold, it is usually a medium-range deviation caused by ambient temperature fluctuations or device drift. It is determined to be a medium deviation condition. The current chip temperature or the current ambient temperature is obtained and compared with the preset temperature threshold. The tuning scheme is selected based on the comparison result.

[0072] Specifically, step S303 includes the following steps: Specifically, in S3031, when the condition is determined to be a moderate deviation and the detected current chip temperature is less than a preset temperature threshold, the second thermoelectric synergy parameter is calculated using a standard vernier caliper-style step tuning strategy. The calculation formula is as follows: λ1 = N × Q, λ2 = λ1 - λ0; Calculate; where λ0 is the wavelength deviation, λ1 is the target thermal tuning amplitude, λ2 is the target electrical tuning amplitude, Q is the tuning step size of the coarse tuning unit, N is the number of tuning steps of the coarse tuning unit, that is, the wavelength redshift corresponding to each control step of thermal tuning, which is equivalent to the scale interval of the vernier caliper main scale; N is the number of tuning steps of the coarse tuning unit, which is the smallest positive integer that satisfies λ1≥λ0.

[0073] The physical principle behind this calculation logic is as follows: thermal tuning can only achieve a redshift of the wavelength, not a reverse blueshift. Therefore, the total amplitude of thermal tuning must be greater than or equal to the wavelength deviation, i.e., over-tuning upwards by at least one step. The excess wavelength offset caused by over-tuning is then precisely compensated for by a reverse blueshift using capacitive tuning, ultimately achieving accurate alignment of the resonant wavelength. In this mode, thermal tuning performs coarse adjustment with a fixed step size, while capacitive tuning completes fine adjustment with sub-step precision, completely replicating the working principle of a vernier caliper. This allows for high-precision wavelength calibration without blind spots across the entire tuning range.

[0074] For example, Q=0.2nm, the current wavelength deviation λ0=0.5nm, the smallest positive integer N=3 that satisfies λ1≥0.5nm, therefore the target thermal tuning amplitude λ1=3×0.2=0.6nm, the target electrical tuning amplitude λ2=0.6-0.5=0.1nm, and finally the total deviation calibration of 0.5nm is achieved by superimposing a thermal red shift of 0.6nm with an electrical blue shift of 0.1nm.

[0075] In this embodiment, the single-step nominal tuning scale value Q of the coarse tuning unit is optimized and determined by the weighted cost function extremum method to achieve an optimal balance between tuning speed and ESC margin. The specific method for obtaining the value is as follows: S30311, obtain basic hardware parameters.

[0076] In some embodiments, the maximum effective blue-shift tuning range λ_elec_max of the capacitor tuning module within the safe operating bias range is determined in advance (the specific measurement method is prior art and is not the focus of this application, so it will not be described in detail here), the maximum red-shift tuning range λ_thermal_max of the heating tuning module under full-scale drive power is determined in advance (the specific measurement method is prior art and is not the focus of this application, so it will not be described in detail here), and the effective number of bits n of the digital-to-analog converter in the thermal tuning drive circuit is obtained.

[0077] S20312, calculate the physical boundary constraints for the Q value.

[0078] The upper limit constraint is determined by the effective range of the capacitor tuning. To reserve a portion of the electronically controlled range for temperature drift compensation during subsequent steady-state operation, a steady-state margin coefficient α is introduced. The value of α ranges from 0.1 to 0.3; in this embodiment, it is set to 0.2. Specifically, the formula for calculating the upper limit constraint is: Q_upper=(1 α)×λ_elec_max; This constraint ensures that any overtuning caused by any hot-tuning step can be fully compensated by capacitor tuning, eliminating the tuning blind zone in the entire tuning range from the root.

[0079] The lower limit constraint is determined by the inherent resolution of the driving hardware, i.e., the wavelength offset corresponding to a single code value of the digital-to-analog converter, calculated using the following formula: Q_lower=λ_thermal_max / (2 n 1); This constraint is the minimum tuning step size that can be achieved in hardware; the Q value cannot be less than this physical limit.

[0080] S30313, construct the total cost function and solve for the preliminary optimal value.

[0081] Based on the typical initial wavelength deviation λ0_avg of the system, a total cost function is constructed that simultaneously includes the cost of tuning speed and the cost of electronic control margin. J (Q) = k1×(λ0_avg / Q) + k2×Q; Wherein, k1 is the tuning speed weighting coefficient, k2=k0 / Qref is the ESC margin weighting coefficient, Qref is the preset reference step size (preferably, Qref is the geometric mean of Q_upper or Q_lower), and the two can be configured according to the performance priority of the system; k1×(λ0_avg / Q) is the tuning speed cost item, the number of hot-tuning steps is inversely proportional to the step size Q, the larger Q is, the fewer the steps, the faster the tuning speed, and the lower the corresponding speed cost; k2×Q is the ESC margin occupancy cost item, the maximum overtuning amount in a single tuning is equal to Q, the larger Q is, the more ESC range is occupied, the less the remaining steady-state margin, and the higher the corresponding margin cost.

[0082] Furthermore, by taking the first derivative of the total cost function J(Q) with respect to Q and setting the first derivative to zero, we can obtain the preliminary optimal Q value Q_opt when the cost is minimized. dJ / dQ = -k1×λ0_avg / Q 2 Solving for +k2=0, we get: .

[0083] S30314, boundary correction yields the final Q value.

[0084] The preliminary optimal Q-value Q_opt obtained from the analysis is compared with the physical boundary constraints, and corrections are made based on the comparison results.

[0085] When Q_opt≥Q_upper, it means that the theoretically optimal step size has exceeded the upper limit that capacitor tuning can cover. At this time, Q=Q_upper is taken to achieve the fastest tuning speed while ensuring no tuning blind zone.

[0086] When Q_lower<Q_opt<Q_upper, it indicates that the theoretical optimal step size falls within the physically feasible interval, and Q=Q_opt is adopted at this time, so that the tuning speed and the electronic tuning margin reach a comprehensively optimal balance.

[0087] When Q_opt≤Q_lower, it indicates that the theoretical optimal step size is smaller than the minimum step size achievable by hardware, and Q=Q_lower is adopted at this time, and tuning is performed with the limit precision of the hardware.

[0088] In this embodiment, different application scenarios can be adapted by adjusting the ratio of the weight coefficients k1 and k2. In speed-priority scenarios, k1 / k2=3~5 is adopted, and the optimal Q is closer to the upper limit; in the balance mode, k1 / k2=1 is adopted, and the comprehensive performance is optimal; in margin-priority scenarios, k1 / k2=0.2~0.5 is adopted, the optimal Q is smaller, and more electronic tuning steady-state margin is reserved.

[0089] S3032 When it is determined as a medium deviation working condition, and the detected current chip temperature or current ambient temperature is greater than or equal to the preset temperature threshold, the continuous working duration of the microring modulator at the target working wavelength is further obtained, the continuous working duration is compared with a preset duration threshold, and a tuning scheme is selected according to the comparison result.

[0090] Specifically, if the continuous working duration of the microring modulator at the target working wavelength is less than the preset duration threshold, it indicates that the time for thermal tuning of the microring modulator is relatively short. Although the current chip temperature is high, the heat generated by the microring modulator is still within the tolerable range in a short time, and the thermal accumulation generated may not be serious. Therefore, thermoelectric cooperative tuning is adopted, the second thermoelectric cooperative parameter calculation is performed, and vernier-type thermoelectric cooperative tuning is adopted to ensure tuning accuracy and range; If the continuous working duration is greater than or equal to the preset duration threshold, it indicates that the chip is in a long-term high-temperature working condition. Long-term heating will further increase the chip temperature, and the risk of inter-channel thermal crosstalk is greatly increased, and even the expected thermal tuning effect cannot be achieved. Therefore, the thermal tuning amplitude should be appropriately reduced at this time to appropriately reduce the heat generation from the heat source; specifically, new thermoelectric cooperative parameters (such as the subsequent third thermoelectric cooperative parameter) are calculated based on the same principle as the calculation method of the second thermoelectric cooperative parameter. Preferably, the tuning amplitude is reduced by reducing the tuning step size or / and the number of tuning steps in the second thermoelectric cooperative parameter.

[0091] In some embodiments, the preset time period threshold is set according to the chip's thermal reliability index, typically ranging from tens of minutes to several hours; the chip temperature is acquired in real time by an on-chip integrated temperature sensor. In some embodiments, the continuous operating time refers to the continuous operating time of the micro-ring modulator under the same target operating wavelength. During this continuous operating time, the micro-ring modulator may correspond to different computational subtasks, but all of these subtasks are based on the same target operating wavelength. Specifically, the continuous operating time is estimated in advance based on historical data statistical analysis of the same or similar large-scale model computation tasks when determining the tuning strategy for the current target operating wavelength. Because the tuning strategies used by the same or similar large-scale model computation tasks are similar, but may differ due to differences in the actual working environment or conditions, the tuning strategies used by the same or similar large-scale model computation tasks cannot be directly and completely applied. However, the continuous operating time of the micro-ring modulator under the same target operating wavelength can be roughly estimated using historical data from the same or similar large-scale model computation tasks, and the target thermal tuning amplitude can be dynamically adjusted in conjunction with the current chip temperature or ambient temperature.

[0092] For example, a computational task involving a large model is typically divided into multiple computational subtasks executed by different photonic computing units. Data for some of these subtasks may be loaded onto the same target operating wavelength for transmission, and this target operating wavelength may be provided by the same microring modulator. Furthermore, the microring modulator may need to provide different target operating wavelengths at different computational stages. For instance, during the T1-T2 time period, a microring modulator utilizes an electrothermal co-tuning strategy to provide the target operating wavelength λ. 11 During the T2-T3 time period, the micro-ring modulator utilizes an electrothermal co-tuning strategy to provide the target operating wavelength λ. 12 The micro-ring modulator operates from the target operating wavelength λ. 11 Switch to the target operating wavelength λ 12 Previously (e.g., when approaching T2, or at the target operating wavelength λ) 11 For calculation subtasks that are about to end, it is necessary to first determine whether the time period T2-T3 is greater than or equal to the preset duration threshold. If it is less than the preset duration threshold, that is, the continuous working time of the micro-ring modulator is not too long, even if the current chip temperature is high, the system can tolerate it because the continuous working time is not too long. Therefore, the second electrothermal coordination parameter is calculated based on the same principle as above to perform electrothermal coordination. If the duration is greater than or equal to a preset time threshold, it indicates that the current chip temperature is already relatively high. Since thermal tuning itself generates heat, a longer thermal tuning time may cause a significant further increase in chip temperature, thus exacerbating thermal crosstalk between channels and potentially failing to achieve the desired thermal coordination effect. Therefore, the thermal tuning duration should be appropriately reduced. Specifically, if the continuous operating time is greater than or equal to a preset time threshold, a third electrothermal coordination parameter calculation is performed to determine the target thermal tuning amplitude and the target electrical tuning amplitude of the micro-ring modulator. λ1' = N' × Q', λ2' = λ1' - λ0 is calculated, where λ1' is the target thermal tuning amplitude, λ2' is the target electrical tuning amplitude, Q' is the tuning step size of the heating tuning module, N' is the number of tuning steps of the heating tuning module, and λ1' < λ1.

[0093] For example, λ1' = N' × Q' = (N - N0) × Q, λ2' = λ1' - λ0; where N0 is the preset reduction tuning step number. Another example is λ1' = N' × Q' = N × (Q - Q0), λ2' = λ1' - λ0; where Q0 is the preset reduction step size. Of course, both the tuning step number and the tuning step size can be reduced simultaneously, with the ultimate goal of reducing λ1 to λ1'. It's even possible to directly preset a reduction amplitude, such that λ1 - preset amplitude reduction = λ1'. That is to say, the focus of this application is not on how to reduce λ1 to λ1', but on using different electrothermal tuning coordination methods according to different ambient temperatures or chip temperatures.

[0094] Of course, N0 or Q0 can be further refined according to the actual situation. For example, the longer the continuous working time, the larger N0 or Q0 is, and the shorter the continuous working time, the smaller N0 or Q0 is.

[0095] Step S400, pure electric tuning process.

[0096] When the wavelength deviation is less than the first wavelength threshold, the target thermal tuning amplitude is set to a preset value, such as 0. The coarse tuning unit remains inactive, and the target electrical tuning amplitude of the micro-ring modulator is determined based on the wavelength deviation. This target electrical tuning amplitude is the blue shift generated by electrical tuning. The fine tuning unit is then activated to perform electrical tuning until the target electrical tuning amplitude is reached, thereby adjusting the resonant wavelength of the micro-ring modulator to the target operating wavelength. This scheme offers the fastest tuning speed and no additional heat dissipation, making it suitable for rapid calibration of small-range wavelength drift.

[0097] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0098] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a computer terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0099] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A tuning system for a micro-ring modulator, characterized in that: It includes a substrate, a bus waveguide and a micro-ring waveguide formed on the top silicon layer of the substrate, wherein the bus waveguide is provided with an input port and an output port, and the micro-ring waveguide is coupled to the bus waveguide via an evanescent wave. The micro-ring waveguide is divided into a capacitor tuning region and a modulation region along the circumference; and a thermal resistance tuning region is provided on its outer side. The thermal resistance tuning region generates Joule heating when energized, which raises the waveguide temperature and causes a red shift in the resonant wavelength of the modulation region, thus forming a coarse tuning unit. When a forward bias voltage is applied, the capacitor tuning region reduces the waveguide refractive index through the plasma dispersion effect, causing a blue shift in the resonant wavelength of the modulation region, thus forming a fine tuning unit. The modulation region is used to load radio frequency signals to achieve electro-optic modulation; It also includes a control unit, which is electrically connected to the coarse tuning unit and the fine tuning unit respectively; the control unit is configured to perform a vernier caliper-type graded tuning method to tune the modulation region so that the resonant wavelength of the modulation region reaches the target operating wavelength.

2. The tuning system for a micro-ring modulator according to claim 1, characterized in that: The coarse tuning unit also includes a heating resistor structure acting in the thermal resistance tuning region and a first electrode group connected to the heating resistor structure; the heating resistor structure is a doped silicon resistor or a deposited titanium nitride thin film resistor, and the first electrode group includes a first tuning electrode and a second tuning electrode respectively electrically connected to both ends of the heating resistor.

3. The tuning system for a micro-ring modulator according to claim 1, characterized in that: The fine tuning unit also includes a MOS capacitor doped structure and a second electrode group connected to the MOS capacitor doped structure; the MOS capacitor doped structure is a lateral MOS capacitor structure, which forms a carrier accumulation layer at the waveguide interface under forward bias to change the effective refractive index of the waveguide.

4. The tuning system for a micro-ring modulator according to claim 1, characterized in that: The modulation region is provided with a PN junction structure and a third electrode group connected to the PN junction structure; the PN junction operates in a reverse bias state, and the third electrode group includes differential radio frequency electrodes.

5. The tuning system for a micro-ring modulator according to claim 1, characterized in that: The control unit includes two digital-to-analog conversion modules, one of which is a coarse-tuning digital-to-analog conversion module electrically connected to the thermal resistance tuning area, and the other is a fine-tuning digital-to-analog conversion module electrically connected to the capacitor tuning area.

6. The tuning system for a micro-ring modulator according to claim 1, characterized in that, The control unit specifically includes: The wavelength deviation acquisition subunit is configured to acquire the wavelength deviation between the initial resonant wavelength of the micro-ring modulator and the target operating wavelength, wherein the wavelength deviation is the difference between the target operating wavelength and the initial resonant wavelength. The judgment subunit is configured to determine whether the wavelength deviation is greater than or equal to a first wavelength threshold. The first tuning subunit is configured to, when the wavelength deviation is greater than or equal to a first wavelength threshold, determine the target thermal tuning amplitude and the target electrical tuning amplitude of the micro-ring modulator based on the wavelength deviation, wherein the target thermal tuning amplitude is the red shift generated by thermal tuning and the target electrical tuning amplitude is the blue shift generated by electrical tuning; and to activate the coarse tuning unit to perform thermal tuning until the target thermal tuning amplitude is reached, and then activate the fine tuning unit to perform electrical tuning until the target electrical tuning amplitude is reached, thereby adjusting the resonant wavelength of the micro-ring modulator to the target operating wavelength; The second tuning subunit is configured to set the target thermal tuning amplitude to 0 when the wavelength deviation is less than the first wavelength threshold, determine the target electrical tuning amplitude of the micro-ring modulator based on the wavelength deviation, the target electrical tuning amplitude being the blue shift generated by electrical tuning; and initiate the fine tuning unit to perform electrical tuning until the target electrical tuning amplitude is reached, thereby adjusting the resonant wavelength of the micro-ring modulator to the target operating wavelength.

7. The tuning system for a micro-ring modulator according to claim 6, characterized in that, The first tuning subunit is further configured to: compare the wavelength deviation with a second wavelength threshold, wherein the second wavelength threshold is greater than the first wavelength threshold; if the wavelength deviation is greater than or equal to the second wavelength threshold, it is determined to be a large deviation condition, and the first thermoelectric synergy parameter is calculated; if the wavelength deviation is greater than or equal to the first wavelength threshold and less than the second wavelength threshold, it is determined to be a medium deviation condition, the current chip temperature or the current ambient temperature is obtained, the current chip temperature or the current ambient temperature is compared with a preset temperature threshold, and a tuning scheme is selected based on the comparison result.

8. The tuning system for a micro-ring modulator according to claim 7, characterized in that, When the condition is determined to be a large deviation, the first tuning subunit is specifically configured to calculate the first thermoelectric synergy parameter using the following formula: λ1 = C, Calculate λ2 = λ1 - λ0; Where λ0 is the wavelength deviation, λ1 is the target thermal tuning amplitude, λ2 is the target electrical tuning amplitude, and C is the preset fixed thermal tuning amplitude. The value of C is 30% to 50% of the maximum tuning range of the coarse tuning unit, and satisfies C - λ0 ≤ the maximum tuning range of the fine tuning unit.

9. The tuning system for a micro-ring modulator according to claim 7, characterized in that, The first tuning subunit is specifically configured to calculate the second thermoelectric synergy parameter using the following formula when the ambient temperature or chip temperature is determined to be less than a preset temperature threshold under moderate deviation conditions: λ1 = N×Q, Calculate λ2 = λ1 - λ0; Where λ0 is the wavelength deviation, λ1 is the target thermal tuning amplitude, λ2 is the target electrical tuning amplitude, Q is the tuning step size of the coarse tuning unit, and N is the number of tuning steps of the coarse tuning unit.

10. A tuning system for a micro-ring modulator according to claim 9, characterized in that, The first tuning subunit is specifically configured to obtain the maximum effective blue-shift tuning range of the fine tuning unit and the maximum red-shift tuning range under full-scale drive of the coarse tuning unit; calculate the physical boundary constraints of the tuning step size Q using the maximum effective blue-shift tuning range and the maximum red-shift tuning range; construct a total cost function that includes both tuning speed cost and electronic control margin cost, and solve it to obtain a preliminary optimal Q value; and correct the preliminary optimal Q value using the physical boundary constraints to obtain the final Q value.

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