An optical computing array based on germanium modulators

Abstract

The present invention belongs to the technical field of semiconductor optoelectronic devices, and specifically relates to an optical computing array based on a germanium modulator, comprising a cross matrix, wherein the cross matrix is ​​formed by crossing multiple rows of mutually parallel input optical waveguides and multiple columns of mutually parallel output optical waveguides; and a photodetector is provided at the output end of each column of the output optical waveguide; multiple optical splitters; multiple germanium modulators, each of the germanium modulators corresponds to one of the cross waveguides, and the first input end of the germanium modulator is connected to the output end of the optical splitter through a transmission optical waveguide; and multiple optical combiners, each of the optical combiners is respectively connected to the output end of the germanium modulator and the output optical waveguide. Through the above structure, the present application comprehensively provides a computing array with a high responsiveness having a thermal compensation mechanism and capable of reducing light reflection, so as to realize a solution for a low-power large-scale integrated computing array under the condition of frequent switching.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor optoelectronic devices, and in particular relates to an optical computing array based on germanium modulators. Background Art

[0002] Optical computing technology, as a next-generation high-performance computing architecture, demonstrates tremendous potential in fields such as artificial intelligence and signal processing due to its high parallelism and low latency. Its core performance metrics are primarily determined by total computing bandwidth, power consumption, and system stability. While the amount of data processed per unit time increases linearly with the scale of computing, the power consumption of the optical chip weight units in optoelectronic fusion systems increases quadratically, leading to a sharp increase in overall power consumption. This contradiction has become a key bottleneck restricting the practical application of optical computing chips.

[0003] Among the current mainstream technical solutions, optical computing architectures based on phase-change materials (PCMs) (such as the prior art CN111684343B) achieve weight modulation through reversible transitions between the material's crystalline and amorphous states. While this solution offers extremely low static power consumption (down to the microwatt level) and the ability to integrate large-scale matrices, the phase change process introduces thermal accumulation effects, limiting the material's response speed (typically in the hundreds of nanoseconds), making it difficult to meet the frequent millisecond-level switching requirements of weight parameters in deep learning training scenarios. Furthermore, frequent switching significantly increases dynamic power consumption (up to the milliwatt-per-unit level), reducing system energy efficiency.

[0004] Another type of optical computing scheme based on carrier absorption (such as the applicant's prior application CN116736933A) achieves optical modulation by manipulating the free-carrier concentration under forward bias. These devices offer nanosecond response speeds, enabling training-level weight update frequencies. However, their high forward current (typically >100 μA / cell) significantly increases overall power consumption (typically >10 mW / cell) when constructing large-scale arrays, making it difficult to meet the energy efficiency requirements of highly integrated systems. Furthermore, prolonged high-current operation can lead to device reliability issues.

[0005] In response to the above technical defects, there is an urgent need for an optical computing chip solution that takes into account low operating power consumption, high switching tolerance and large-scale integration capabilities. Summary of the Invention

[0006] The object of the present invention is to provide an optical computing array based on germanium modulators to partially alleviate or solve the above-mentioned shortcomings and reduce the power consumption of large-scale optical computing chips.

[0007] In order to solve the above-mentioned technical problems, the present invention specifically adopts the following technical solutions:

[0008] An optical computing array based on germanium modulators, comprising:

[0009] A cross matrix, wherein the cross matrix is ​​formed by crossing multiple rows of mutually parallel input optical waveguides and multiple columns of mutually parallel output optical waveguides; and a photodetector is provided at the output end of each column of the output optical waveguide;

[0010] A plurality of optical splitters, each of which is provided at the front end of a cross waveguide formed by each row of input optical waveguides and each column of output optical waveguides;

[0011] a plurality of germanium modulators, each of the germanium modulators corresponding to one of the cross waveguides, and a first input end of the germanium modulator being connected to an output end of the optical splitter through a transmission optical waveguide;

[0012] a plurality of optical combiners, each of which is connected to the output end of the germanium modulator and the output optical waveguide, and is used to combine the first optical signal of the corresponding cross waveguide and the second optical signal output by the germanium modulator into a third optical signal, and transmit the third optical signal to the next cross waveguide on the same output optical waveguide;

[0013] In which, the photoelectric characteristics of the light absorption layer in the germanium modulator can be changed by writing a control signal into its second input terminal, and the germanium modulator can generate a second light signal based on the first light signal input into the first input terminal and send it to the light combiner; the photoelectric characteristics include the light absorption coefficient.

[0014] As an improvement, the germanium modulator includes: a silicon substrate and an insulating layer deposited on the silicon substrate; a waveguide layer is provided on the insulating layer; a germanium absorption layer is embedded in the waveguide layer; a first depth of the germanium absorption layer embedded in the waveguide layer is less than the thickness of the waveguide layer, or a second depth of the germanium absorption layer embedded in the waveguide layer is equal to the thickness of the waveguide layer;

[0015] A heating unit is provided on the top and / or bottom of the germanium absorption layer, and the heating unit extends along the length direction of the germanium absorption layer; or,

[0016] Heating units are respectively provided on both sides of the germanium absorption layer, and the heating units extend along the length direction of the germanium absorption layer; or,

[0017] Heating unit groups are respectively provided on both sides of the germanium absorption layer, and the heating unit group on each side includes a plurality of heating units evenly spaced along the length direction of the germanium absorption layer, wherein the heating levels of two adjacent heating units on the same side are primary heating and secondary heating respectively;

[0018] The heating unit is used to change the photoelectric properties of the light absorbing layer.

[0019] As an improvement, the germanium absorption layer includes a light guiding region and a light absorption region sequentially arranged along the light propagation direction.

[0020] The cross-sectional area of ​​the light guiding region gradually increases from the incident end in a direction close to the light absorbing region; and the cross-sectional area of ​​the light absorbing region is the same along the light propagation direction.

[0021] As an improvement, when the light guiding area is viewed from above, its width gradually increases from the incident end along the direction of light propagation; and when the light guiding area is viewed from the side, its width gradually decreases from the top to the bottom; or, the interface between the light guiding area and the waveguide layer is fan-shaped; and / or, the cross-section of the light absorption area is rectangular.

[0022] As an improvement, the width and length of the heating unit located on the top and / or bottom of the germanium absorption layer are both smaller than the width and length of the germanium absorption layer.

[0023] An optical computing array based on germanium modulators, comprising:

[0024] A cross matrix, wherein the cross matrix is ​​formed by crossing multiple rows of mutually parallel input optical waveguides and multiple columns of mutually parallel electrical buses;

[0025] a plurality of optical splitters, each of which is provided at a front end of an intersection node between each row of optical input waveguides and each column of electrical buses;

[0026] a plurality of germanium modulators, each of the germanium modulators corresponding to one of the cross nodes, and a first input end of the germanium modulator being connected to an output end of the optical splitter via a transmission optical waveguide;

[0027] a plurality of first photodetectors, each of which is connected to the output end of the germanium modulator and the electrical bus, and is used to convert the optical signal output by the germanium modulator into an electrical signal and send the electrical signal to the electrical bus;

[0028] The photoelectric characteristics of the light absorption layer in the germanium modulator can be changed by writing a control signal into its second input terminal, and the germanium modulator can generate a second light signal based on the first light signal inputted through the first input terminal and send the second light signal to the first photodetector; the photoelectric characteristics include a light absorption coefficient;

[0029] The product of the multiplier value and the multiplicand value is encoded in the optical signal.

[0030] As an improvement, the germanium modulator includes: a silicon substrate and an insulating layer deposited on the silicon substrate; a waveguide layer is provided on the insulating layer; a germanium absorption layer is embedded in the waveguide layer; a first depth of the germanium absorption layer embedded in the waveguide layer is less than the thickness of the waveguide layer, or a second depth of the germanium absorption layer embedded in the waveguide layer is equal to the thickness of the waveguide layer;

[0031] A heating unit is provided on the top and / or bottom of the germanium absorption layer, and the heating unit extends along the length direction of the germanium absorption layer; or,

[0032] Heating units are respectively provided on both sides of the germanium absorption layer, and the heating units extend along the length direction of the germanium absorption layer; or,

[0033] Heating unit groups are respectively provided on both sides of the germanium absorption layer, and the heating unit group on each side includes a plurality of heating units evenly spaced along the length direction of the germanium absorption layer, wherein the heating levels of two adjacent heating units on the same side are primary heating and secondary heating, respectively.

[0034] As an improvement, the germanium absorption layer includes a light guiding region and a light absorption region sequentially arranged along the light propagation direction.

[0035] The cross-sectional area of ​​the light guiding region gradually increases from the incident end in a direction close to the light absorbing region; and the cross-sectional area of ​​the light absorbing region is the same along the light propagation direction.

[0036] As an improvement, when the light guiding area is viewed from above, its width gradually increases from the incident end along the direction of light propagation; and when the light guiding area is viewed from the side, its width gradually decreases from the top to the bottom; or, the interface between the light guiding area and the waveguide layer is fan-shaped; and / or, the cross-section of the light absorption area is rectangular.

[0037] As an improvement, the width and length of the heating unit located at the top and / or bottom of the germanium absorption layer are both smaller than the width and length of the germanium absorption layer. The principle and beneficial technical effects of the present invention are:

[0038] In response to the millisecond-level frequent switching requirements in deep learning training scenarios, this application provides a high-responsive computing array with a thermal compensation mechanism that can reduce light reflection, so as to achieve the design of a low-power large-scale integrated computing array while meeting the conditions of frequent switching.

[0039] In contrast to the existing methods of using phase change materials for modulation, or changing the carrier concentration by injecting current or applying voltage in the doping to change the light absorption coefficient, the present application provides an optical computing array based on a reverse-biased germanium modulator, while also achieving multiple controls on the light absorption characteristics of the germanium absorption layer.

[0040] First, the present application regulates the photoresponsivity of the germanium modulator through voltage. The dark current of the germanium modulator under reverse bias is extremely low, and its photocurrent during operation can be at least 2 orders of magnitude smaller than that of the forward-conducting carrier absorption modulator or phase change material modulator, thereby effectively reducing the power consumption of a single device during operation.

[0041] Furthermore, a heating unit is provided on at least one side of the germanium absorption layer, coupled with a real-time feedback mechanism to ensure temperature consistency and uniformity across the entire germanium absorption layer. This increases the number of electrons available for transition to the valence band, thereby changing the optical absorption coefficient of the germanium absorption layer and reducing the operating voltage of the electro-absorption modulator. Furthermore, when an anomaly such as signal distortion caused by temperature is detected (e.g., high system temperature due to high system power consumption, or high temperature during the heating unit modulation process), the heating unit within the optical computing array can be used for temperature compensation, eliminating the need for a separate temperature compensation module external to the optical computing array. In other words, the dual-purpose heating unit can both change the optical absorption coefficient of the absorption layer and provide temperature compensation to mitigate signal distortion.

[0042] Furthermore, in the case where the light absorption cross-sectional area of ​​the light absorption region (germanium absorption layer) is large (for example, "full etching"), the present application designs a partitioned design for the germanium absorption layer (light guiding region and light absorption region), and guides the light signal transmitted from the optical waveguide through a gradient interface formed by gradually changing the height and width of the light guiding region. That is, the cross-sectional area of ​​the light guiding region gradually increases in height and length from the incident end, which can greatly reduce the reflection of light at the incident end when propagating in the light absorption layer (germanium absorption layer) with a larger cross-sectional area, thereby improving the light absorption rate of the modulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the embodiments or the description of the prior art. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the various elements or parts are not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without inventive work.

[0044] Figure 1 FIG1 is an exemplary side view of a modulator in Embodiment 2 of the present invention;

[0045] Figure 2 is another exemplary side view of the modulator in the second embodiment of the present invention;

[0046] Figure 3 is another exemplary side view of the modulator in the second embodiment of the present invention;

[0047] Figure 4 is a top view of the modulator in the second embodiment of the present invention;

[0048] Figure 5 It is a front view of the germanium absorption layer in the second embodiment of the present invention;

[0049] Figure 6 is a top view of the germanium absorption layer in Example 2 of the present invention;

[0050] Figure 7 Schematic diagram of the structure of an exemplary optical computing array in Embodiment 1 of the present invention;

[0051] Figure 8 FIG. 4 is a schematic structural diagram of another exemplary optical computing array in the first embodiment of the present invention.

[0052] Markings in the figure: 1. Silicon substrate; 2. Waveguide layer; 3. Heating unit; 4. Insulating layer; 5. Germanium absorption layer; 51. Light guiding region; 52. Light absorption region; 6. Electrode; 7. Silicon ribbon; 8. Optical computing unit; 101. Germanium modulator; 102. Input optical waveguide; 103. Transmission optical waveguide; 104. Output optical waveguide; 105. Electrical bus; 106. First photodetector. DETAILED DESCRIPTION

[0053] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0054] Herein, the use of suffixes such as "module", "component" or "unit" to indicate elements is only for the purpose of facilitating the description of the present invention and has no specific meaning in itself. Therefore, "module", "component" or "unit" can be used interchangeably. Herein, the orientation or positional relationship indicated by the terms "upper", "lower", "inside", "outside", "front", "back", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0055] As used herein, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood broadly. For example, "connected" can mean fixed, removable, or integral; it can mean mechanical, direct, or indirect through an intermediary, or it can mean internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention. As used herein, "plurality" means two or more, including two, three, four, five, etc.

[0056] In this context, an optical splitter can utilize components such as optical waveguides, optical couplers, heaters, and phase shifters with specific structures to distribute optical signals within the chip, either actively or passively. Similarly, an optical combiner can utilize components such as optical waveguides, optical couplers, heaters, and phase shifters with specific structures to sum optical signals within the chip, either actively or passively.

[0057] Example 1

[0058] The present invention provides an optical computing array based on a germanium modulator, comprising:

[0059] A cross matrix is ​​formed by multiple rows of mutually parallel input channels and multiple columns of mutually parallel output channels, and a photodetector is provided at the output end of the output optical waveguide in each column.

[0060] A plurality of optical splitters are arranged at the front end of the intersection channel formed by each row of optical input channels and each column of output channels.

[0061] Multiple signal processing units, each corresponding to one of the cross channels, and a first input end of each signal processing unit connected to an output end of the optical splitter via a transmission optical waveguide; the transmission optical waveguide can be made of one of the following optical waveguide materials: silicon (Si), silicon oxide (SiO2), silicon nitride (SiN), indium phosphide (InP), gallium phosphide (GaP), germanium (Ge), lithium niobate (LiNbO3), aluminum nitride (AlN), or any Group IV or Group III-V semiconductor with a band gap greater than the wavelength of light.

[0062] The signal processing unit is a germanium modulator, or the signal processing unit includes a germanium modulator and a photodetector.

[0063] Multiple light combiners, each of which is connected to the output end of the signal processing unit and the output channel, and is used to combine the first signal of the corresponding cross channel and the second signal output by the signal processing unit into a third signal, and transmit it to the next cross channel on the same output channel.

[0064] Compared with the existing method of using phase change materials for modulation, or changing the carrier concentration by injecting current or applying voltage in the doping to change the light absorption coefficient. This application proposes a solution that is completely different from the existing technology to meet the needs of frequent switching in milliseconds in deep learning training scenarios. This application provides an optical computing array based on a reverse-biased germanium modulator. The light response of the germanium modulator is regulated by voltage. The dark current of the germanium modulator under reverse bias is extremely low. The photocurrent during operation can be at least 2 orders of magnitude smaller than that of the forward-conducting carrier absorption modulator or phase change material modulator, thereby effectively reducing the power consumption of a single device during operation.

[0065] In some embodiments, the input channel is an input optical waveguide, the output channel is an output optical waveguide, and accordingly, the signal processing unit is a germanium modulator.

[0066] Specifically, the optical computing array includes:

[0067] A cross matrix is ​​formed by crossing multiple rows of mutually parallel input optical waveguides and multiple columns of mutually parallel output optical waveguides; and a photodetector is provided at the output end of each column of the output optical waveguide; preferably, the input optical waveguide and the output optical waveguide are arranged vertically.

[0068] A plurality of optical splitters are provided at the front end of a cross waveguide formed by each row of input optical waveguides and each column of output optical waveguides; preferably, the optical splitter is provided at the front end of the input optical waveguide in the cross waveguide.

[0069] a plurality of germanium modulators, each of the germanium modulators corresponding to one of the cross waveguides, and a first input end of the germanium modulator being connected to an output end of the optical splitter through a transmission optical waveguide;

[0070] a plurality of optical combiners, each of which is connected to the output end of the germanium modulator and the output optical waveguide, and is used to combine the first optical signal of the corresponding cross waveguide and the second optical signal output by the germanium modulator into a third optical signal, and transmit the third optical signal to the next cross waveguide on the same output optical waveguide;

[0071] In which, the photoelectric characteristics of the light absorption layer in the germanium modulator can be changed by writing a control signal into its second input terminal, and the germanium modulator can generate a second light signal based on the first light signal input into the first input terminal and send it to the light combiner; the photoelectric characteristics include the light absorption coefficient.

[0072] That is, multiple rows of input optical waveguides and multiple rows of output optical waveguides are arranged crosswise to divide the optical computing array into multiple optical computing units, each of which includes a cross waveguide and a splitter, a germanium modulator and a combiner arranged at different positions of the cross waveguide.

[0073] In other embodiments, the input channel is an input optical waveguide, the output channel is an electrical bus, and accordingly, the signal processing unit is a germanium modulator and a photodetector (also referred to as the first photodetector below).

[0074] Specifically, a cross matrix is ​​formed by crossing multiple rows of mutually parallel input optical waveguides and multiple columns of mutually parallel electrical buses; preferably, the input optical waveguides are perpendicular to the electrical buses.

[0075] A plurality of optical splitters are provided at the front end of the intersection node between each row of optical input waveguides and each column of electrical buses; preferably, the optical splitter is provided at the front end of the input optical waveguide in the intersection waveguide.

[0076] a plurality of germanium modulators, each of the germanium modulators corresponding to one of the cross nodes, and a first input end of the germanium modulator being connected to an output end of the optical splitter via a transmission optical waveguide;

[0077] a plurality of first photodetectors, each of which is connected to the output end of the germanium modulator and the electrical bus, and is used to convert the optical signal output by the germanium modulator into an electrical signal and send the electrical signal to the electrical bus;

[0078] The photoelectric characteristics of the light absorption layer in the germanium modulator can be changed by writing a control signal into its second input terminal, and the germanium modulator can generate a second light signal based on the first light signal inputted through the first input terminal and send the second light signal to the first photodetector; the photoelectric characteristics include a light absorption coefficient;

[0079] The product of the multiplier value and the multiplicand value is encoded in the optical signal.

[0080] That is, multiple rows of input optical waveguides and multiple rows of electrical buses are cross-arranged to divide the optical computing array into multiple optical computing units, each of which includes a cross-waveguide, and a splitter, a germanium modulator, a first photodetector, and a light combiner arranged at different positions of the cross-waveguide.

[0081] Example 2

[0082] This embodiment provides a germanium modulator for use in the optical computing array of the first embodiment, comprising a silicon substrate 1 and an insulating layer 4 deposited on the silicon substrate 1; a waveguide layer 2 is provided on the insulating layer 4; a germanium absorption layer 5 is embedded in the waveguide layer 2; the germanium absorption layer 5 is embedded in the waveguide layer 2 to a first depth less than the thickness of the waveguide layer 2, or the germanium absorption layer 5 is embedded in the waveguide layer 2 to a second depth greater than or equal to the thickness of the waveguide layer 2 (preferably, the second depth of the germanium absorption layer 5 embedded in the waveguide layer 2 is equal to the thickness of the waveguide layer 2, in which case "full etching" is performed).

[0083] When the second depth is equal to the thickness of the waveguide layer 2 , it indicates that the bottom of the germanium absorption layer 5 is flush with the upper surface of the insulating layer 4 ; when the second depth is greater than the thickness of the waveguide layer 2 , it indicates that the germanium absorption layer 5 is embedded in the insulating layer 4 .

[0084] In the above embodiment, when the second depth is equal to the thickness of the waveguide layer 2, that is, the etching ends at the insulating layer 4, on the one hand, the germanium absorption layer 5 can have a larger cross-section, thereby maximizing the overlap time with the light field in the modulation region. At the same length, the responsivity is higher; at the same responsivity, the size is minimized. On the other hand, the etching depth is easy to control, ensuring the consistency of the etched groove depth between different modulators. In traditional shallow etching processes, because the etching depth is shallow and difficult to precisely control, it is easily affected by factors such as uneven silicon layer thickness, resulting in inconsistent etching depth, which in turn affects the performance uniformity of the modulator. Etching grooves that reach deep into the insulating layer 4 has better process stability, which is conducive to the large-scale production of high-quality modulators.

[0085] In some embodiments, a heating unit 3 is provided on at least one side of the germanium absorption layer 5 .

[0086] In some specific embodiments, a heating unit 3 is provided on the top and / or bottom of the germanium absorption layer 5, and the heating unit 3 extends along the length direction of the germanium absorption layer 5; or, heating units 3 are respectively provided on both sides of the germanium absorption layer 5, and the heating units 3 extend along the length direction of the germanium absorption layer 5; or, 3 groups of heating units are respectively provided on both sides of the germanium absorption layer 5, and the 3 groups of heating units on each side include a plurality of heating units 3 evenly spaced along the length direction of the germanium absorption layer 5, wherein the heating levels of two adjacent heating units 3 located on the same side are primary heating and secondary heating, respectively; the heating unit 3 is used to change the photoelectric properties of the light absorption layer.

[0087] Completely different from the traditional approach of relying on high electric field intensity to increase the absorption coefficient and thus ensure the uniformity of the photocurrent density, the present invention provides a thermal compensation mechanism that only targets the end point effect. Specifically, by providing a heating unit 3 on at least one side (bottom and / or top, or front and back sides) of the germanium absorption layer 5, the heating unit 3 acts on the germanium absorption layer 5 along the length direction of the germanium absorption layer to ensure the consistency and uniformity of the temperature of the entire germanium absorption layer 5, thereby increasing the number of electrons that can transition to the valence band, thereby changing the light absorption coefficient of the germanium absorption layer 5 and reducing the operating voltage of the electro-absorption modulator. In this process, it is only necessary to ensure the final light absorption rate (that is, the ratio of input light to output light / input light), without considering the uniformity of the light absorption coefficient of the germanium absorption layer 5.

[0088] In other words, the present application provides a thermal compensation mechanism for dual regulation of the light absorption coefficient only for the endpoint effect. First, the germanium absorption layer is heated to adjust the light absorption coefficient of the germanium absorption layer from the germanium modulator itself. Then, the light absorption coefficient of the germanium absorption layer is further adjusted by adjusting the input voltage. In other words, this process does not require high adjustment of the input voltage, that is, while ensuring low energy consumption, the response speed of the computing array can also be guaranteed, thereby meeting the requirements of large-scale matrices.

[0089] In some embodiments, the germanium modulator further comprises:

[0090] The temperature monitoring module is used to monitor the actual temperature value of the germanium absorption layer 5 in real time.

[0091] a first judgment module, configured to judge whether the actual temperature value monitored by the temperature monitoring module is greater than a first preset temperature threshold, and if so, to generate and send a first control signal indicating that heating is stopped to the heating unit 3 / the heating unit group; and if so, to generate and send a second control signal indicating that monitoring is continued to the temperature monitoring module; and / or,

[0092] The temperature monitoring module is used to monitor in real time the actual temperature value of the germanium absorption layer 5 after being heated by the heating unit 3 which is in a heating state at a first level of heating.

[0093] The second judgment module is used to judge whether the actual temperature value monitored by the temperature monitoring module reaches the preset target temperature threshold after a preset period of time. If not, a third control signal is generated and sent to the heating unit 3 indicating that the starting heating level is secondary heating and is in a dormant state, so that the actual temperature of the germanium absorption layer 5 reaches the preset target temperature threshold.

[0094] Among them, the first temperature threshold can be obtained in advance through a large number of experiments, or pre-set by the user based on experience. When the actual temperature is near the first preset temperature threshold, the number of valence band electrons that can transition tends to be maximized, but at the same time it will not cause too much adverse effects on the material itself.

[0095] The division of heating levels (level one and level two) is only for distinguishing the two and cannot limit their heating power or other characteristics. When only level one heating is turned on, the heating power is small, and when both level one heating and level two heating are turned on at the same time, the heating power increases and the temperature of the germanium absorption layer 5 can also be increased accordingly.

[0096] The present invention regulates the temperature of the germanium absorption layer 5 through a real-time feedback mechanism. On the one hand, it can maximize the number of electrons in the valence band that can transition as much as possible. On the other hand, it can improve the temperature stability of the germanium absorption layer 5 and prevent the problem of unstable light signals emitted by the germanium absorption layer 5 due to frequent changes in the temperature of the germanium absorption layer 5.

[0097] In some embodiments, the germanium absorption layer includes a light guiding region and a light absorption region sequentially arranged along the light propagation direction, wherein the cross-sectional area of ​​the light guiding region gradually increases from the incident end in the direction approaching the light absorption region; the cross-sectional area of ​​the light absorption region is the same along the light propagation direction.

[0098] In some specific embodiments, the longitudinal cross-section of the light-guiding region 51 is a right-angled trapezoid, with the hypotenuse corresponding to the interface between the light-guiding region 51 and the waveguide layer 2, and the angle α between the hypotenuse and the base is 86°-89°. The longitudinal cross-section of the light-absorbing region 52 is rectangular, or the interface between the light-guiding region 51 and the waveguide layer 2 is fan-shaped. The longitudinal cross-section refers to a vertical plane parallel to the length of the germanium absorption layer.

[0099] When the light guiding area is viewed from above, its width gradually increases from the incident end along the direction of light propagation; and when the light guiding area is viewed from the side, its width gradually decreases from the top to the bottom; or, the interface between the light guiding area and the waveguide layer is fan-shaped; and / or, the cross-section of the light absorption area is rectangular.

[0100] The purpose of this arrangement is to achieve a smooth transition in refractive index. Since silicon has a refractive index of approximately 3.4 and germanium has a refractive index of approximately 4.4, this gradual structural change allows the refractive index to gradually transition from waveguide layer 2 (silicon waveguide) to germanium, reducing light reflection at the incident end. When light propagates across the interface of media with different refractive indices, the greater the difference in refractive index, the greater the reflection. This gradual transition structure allows light to flow more smoothly from the silicon waveguide into the germanium absorption layer 5, improving light coupling efficiency and, in turn, enhancing the modulator's light absorption capacity.

[0101] Ideally, the light guiding region is a cone with a smaller front and a larger back. The cone-shaped structure can achieve a more perfect refractive index gradient, minimize the reflection of light when entering the germanium absorption layer 5, and theoretically maximize the light coupling efficiency.

[0102] Due to process limitations, a conical light-guiding region is prohibitively expensive. Therefore, to reduce the manufacturing complexity in this embodiment, the cross-sectional area of ​​the light-guiding region is simply increased gradually from the incident end toward the light-absorbing region 52. For example, the light-guiding region is a triangle with a narrow front and wide back when viewed from above, and a trapezoid with a larger top and smaller bottom when viewed from above. While different from an ideal conical shape, the trapezoidal structure still achieves a certain degree of gradual refractive index change, reducing light reflection, and is a feasible solution under current process conditions.

[0103] That is to say, the present invention restricts the shape of the light guiding region so that the cross-sectional area of ​​the light guiding region gradually increases from the incident end in terms of both height and length, which can greatly reduce the reflection of light at the incident end when it propagates in the light absorption layer (germanium absorption layer) with a larger cross-sectional area, thereby improving the light absorption rate of the modulator. In other words, the present application provides a full etching solution with a thermal compensation mechanism that can reduce light reflection.

[0104] In some embodiments, the width and length of the heating unit 3 located at the top and / or bottom of the germanium absorption layer 5 are both smaller than the width and length of the germanium absorption layer 5. In this way, while ensuring the heating effect, unnecessary heat waste will not be caused. In this embodiment, due to the addition of the germanium absorption layer with the above structure, its light absorption efficiency is improved, but at the same time, once there is an abnormality in the data, such as data distortion, it will be amplified accordingly, making it easier to detect data abnormalities in subsequent processes. There are many factors that lead to data abnormalities. The specific judgment and identification mechanism can be identified using existing technologies, which will not be repeated here. Once it is identified that the data distortion and other abnormalities are caused by temperature, temperature compensation can be performed accordingly through the heating unit.

[0105] In summary, in response to the millisecond-level frequent switching requirements in deep learning training scenarios, this application provides a high-responsive computing array with a thermal compensation mechanism that can reduce light reflection, so as to achieve the design of a low-power large-scale integrated computing array while meeting the conditions of frequent switching.

[0106] In contrast to the existing methods of using phase change materials for modulation, or changing the carrier concentration by injecting current or applying voltage in the doping to change the light absorption coefficient, the present application provides an optical computing array based on a reverse-biased germanium modulator, while also achieving multiple controls on the light absorption characteristics of the germanium absorption layer.

[0107] First, the present application regulates the photoresponsivity of the germanium modulator through voltage. The dark current of the germanium modulator under reverse bias is extremely low, and its photocurrent during operation can be at least 2 orders of magnitude smaller than that of the forward-conducting carrier absorption modulator or phase change material modulator, thereby effectively reducing the power consumption of a single device during operation.

[0108] Furthermore, a heating unit is provided on at least one side of the germanium absorption layer, and a real-time feedback mechanism is provided to ensure the consistency and uniformity of the temperature of the entire germanium absorption layer 5, thereby increasing the number of electrons that can be transferred to the valence band, thereby changing the light absorption coefficient of the germanium absorption layer 5 and reducing the operating voltage of the electro-absorption modulator.

[0109] Furthermore, in the case where the light absorption cross-sectional area of ​​the light absorption region (germanium absorption layer) is large (for example, "full etching"), the present application designs a partitioned design of the germanium absorption layer (light guiding region and light absorption region), and guides the light signal transmitted from the optical waveguide through a gradient interface formed by gradually changing the height and width of the light guiding region. That is, the cross-sectional area of ​​the light guiding region gradually increases from the incident end in terms of both height and length, which can greatly reduce the reflection of light at the incident end when propagating in the light absorption layer (germanium absorption layer) with a larger cross-sectional area, thereby improving the light absorption rate of the modulator.

[0110] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0111] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. An optical computing array based on germanium modulators, characterized in that: include: A cross matrix, wherein the cross matrix is ​​formed by crossing multiple rows of mutually parallel input optical waveguides and multiple columns of mutually parallel electrical buses; a plurality of optical splitters, each of which is provided at a front end of an intersection node between each row of optical input waveguides and each column of electrical buses; a plurality of germanium modulators, each of the germanium modulators corresponding to one of the cross nodes, and a first input end of the germanium modulator being connected to an output end of the optical splitter via a transmission optical waveguide; a plurality of first photodetectors, each of which is connected to the output end of the germanium modulator and the electrical bus, and is used to convert the optical signal output by the germanium modulator into an electrical signal and send the electrical signal to the electrical bus; The photoelectric characteristics of the light absorption layer in the germanium modulator can be changed by writing a control signal into its second input terminal, and the germanium modulator can generate a second light signal based on the first light signal inputted through the first input terminal and send the second light signal to the first photodetector; the photoelectric characteristics include a light absorption coefficient; The product of the multiplier value and the multiplicand value is encoded in the optical signal.

2. The optical computing array according to claim 1, wherein: The germanium modulator comprises: a silicon substrate and an insulating layer deposited on the silicon substrate; a waveguide layer is provided on the insulating layer; a germanium absorption layer is embedded in the waveguide layer; the germanium absorption layer is embedded in the waveguide layer to a first depth less than the thickness of the waveguide layer, or the germanium absorption layer is embedded in the waveguide layer to a second depth equal to the thickness of the waveguide layer; A heating unit is provided on the top and / or bottom of the germanium absorption layer, and the heating unit extends along the length direction of the germanium absorption layer; or, Heating units are respectively provided on both sides of the germanium absorption layer, and the heating units extend along the length direction of the germanium absorption layer; or, Heating unit groups are respectively provided on both sides of the germanium absorption layer, and the heating unit group on each side includes a plurality of heating units evenly spaced along the length direction of the germanium absorption layer, wherein the heating levels of two adjacent heating units on the same side are primary heating and secondary heating, respectively.

3. The optical computing array according to claim 2, wherein: The germanium absorption layer includes a light guiding region and a light absorption region sequentially arranged along the light propagation direction. The cross-sectional area of ​​the light guiding region gradually increases from the incident end in a direction close to the light absorbing region; and the cross-sectional area of ​​the light absorbing region is the same along the light propagation direction.

4. The optical computing array according to claim 3, characterized in that When the light guiding area is viewed from above, its width gradually increases from the incident end along the direction of light propagation; and when the light guiding area is viewed from the side, its width gradually decreases from the top to the bottom; or, the interface between the light guiding area and the waveguide layer is fan-shaped; and / or, the cross-section of the light absorption area is rectangular.

5. The optical computing array according to claim 2, wherein: The width and length of the heating unit located on the top and / or bottom of the germanium absorption layer are both smaller than the width and length of the germanium absorption layer.

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