An optical computing array based on reverse-biased germanium modulators

Abstract

The application belongs to the technical field of semiconductor optoelectronic devices, and particularly relates to a light computing array based on a reverse bias germanium modulator, which comprises a cross matrix formed by multiple rows of parallel input light waveguides and multiple columns of parallel output light waveguides; an optical detector is arranged at the output end of each column of the output light waveguides; multiple light splitters; multiple germanium modulators, each corresponding to one cross waveguide, and the first input end of the germanium modulator being connected with the output end of the light splitter through a transmission light waveguide; and multiple light combiners, each being connected with the output end of the germanium modulator and the output light waveguide. Through the above structure, the application comprehensively provides a high-response computing array with a thermal compensation mechanism and capable of reducing light reflection, so as to realize a scheme of a large-scale integrated computing array with low power consumption under the condition of meeting frequent switching.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor optoelectronic device technology, specifically relating to an optical computing array based on a reverse bias germanium modulator. Background Technology

[0002] Optical computing technology, as a new generation of high-performance computing architecture, has shown great potential in fields such as artificial intelligence and signal processing due to its high parallelism and low latency. Its core performance indicators mainly depend on total computing bandwidth, power consumption, and system stability. As the scale of computing increases, the amount of data processed by the system per unit time grows linearly, but the power consumption of the weighting units of the optical chip in the optoelectronic fusion system 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] In current mainstream technologies, optical computing architectures based on phase change materials (PCMs) (such as the existing technology CN111684343B) achieve weight modulation through the reversible transition between crystalline and amorphous states of the material. While this approach boasts extremely low static power consumption (down to the μW level) and large-scale matrix integration capabilities, its phase transition process suffers from thermal accumulation effects, limiting the material's response speed (typically on the order of hundreds of nanoseconds), making it difficult to meet the millisecond-level frequent switching requirements of weight parameters in deep learning training scenarios. Furthermore, frequent switching significantly increases dynamic power consumption (up to the mW / cell level), leading to a decrease in system energy efficiency.

[0004] Another type of optical computing scheme based on carrier absorption effect (such as the applicant's prior application CN202310669033.4) achieves optical modulation by controlling the free carrier concentration under forward bias. These devices have nanosecond-level response speeds and can support training-level weight update frequencies, but their forward conduction current is large (typically >100 μA / cell), significantly increasing total power consumption when building large-scale arrays (typically >10 mW / cell), making it difficult to meet the energy efficiency requirements of highly integrated systems. Furthermore, long-term high-current operation may cause device reliability issues.

[0005] To address the aforementioned technical shortcomings, there is an urgent need for an optical computing chip solution that balances low power consumption, high switching tolerance, and large-scale integration capabilities. Summary of the Invention

[0006] The purpose of this invention is to provide an optical computing array based on a reverse bias germanium modulator to partially alleviate or solve the above-mentioned shortcomings and reduce the power consumption of large-scale optical computing chips.

[0007] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution:

[0008] An optical computing array based on a reverse-biased germanium modulator includes:

[0009] The cross matrix is ​​formed by multiple rows of parallel input optical waveguides and multiple columns of parallel output optical waveguides; and each column of output optical waveguides is equipped with a photodetector at its output end.

[0010] Multiple beam splitters are disposed at the front end of the cross waveguide formed by each row of input optical waveguides and each column of output optical waveguides;

[0011] Multiple germanium modulators, each of the germanium modulators corresponding to one of the cross waveguides, and the first input terminal of the germanium modulator is connected to the output terminal of the beam splitter via a transmission optical waveguide;

[0012] Multiple optical combiners are provided, each of which is connected to the output terminal of the germanium modulator and the output optical waveguide, respectively, for combining 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 transmitting it to the next cross waveguide on the same output optical waveguide;

[0013] The photoelectric properties of the light absorption layer in the germanium modulator can be changed by writing a control signal to its second input terminal, and the germanium modulator can generate a second light signal based on the first light signal input at the first input terminal and send it to the optical combiner; the photoelectric properties 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 disposed on the insulating layer; a germanium absorption layer embedded in the waveguide layer; a first depth at which the germanium absorption layer is embedded in the waveguide layer is less than the thickness of the waveguide layer, or a second depth at which the germanium absorption layer is embedded in the waveguide layer is equal to the thickness of the waveguide layer;

[0015] A heating unit is provided at 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 disposed 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 arranged on both sides of the germanium absorption layer, and each heating unit group includes multiple heating units evenly spaced along the length of the germanium absorption layer. The heating levels of two adjacent heating units on the same side are first-level heating and second-level 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 absorbing region arranged sequentially along the light propagation direction.

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

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

[0022] 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.

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

[0024] A cross matrix, which is formed by multiple rows of parallel input optical waveguides and multiple columns of parallel electrical busbars;

[0025] Multiple optical splitters are disposed at the front end of the intersection node of each row of optical input waveguides and each column of electrical bus.

[0026] Multiple germanium modulators, each of the germanium modulators corresponding to one of the cross nodes, and the first input terminal of the germanium modulator is connected to the output terminal of the beam splitter via a transmission optical waveguide;

[0027] Multiple first photodetectors are provided, each of which is connected to the output terminal of the germanium modulator and the electrical bus, respectively, for converting the optical signal output by the germanium modulator into an electrical signal and sending it to the electrical bus;

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

[0029] The product of the multiplier and the multiplicand 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 disposed on the insulating layer; a germanium absorption layer embedded in the waveguide layer; a first depth at which the germanium absorption layer is embedded in the waveguide layer is less than the thickness of the waveguide layer, or a second depth at which the germanium absorption layer is embedded in the waveguide layer is equal to the thickness of the waveguide layer;

[0031] A heating unit is provided at 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 disposed 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 arranged on both sides of the germanium absorption layer, and each heating unit group includes multiple heating units evenly spaced along the length of the germanium absorption layer. The heating levels of two adjacent heating units on the same side are first-level heating and second-level heating, respectively.

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

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

[0036] As an improvement, when viewed from above, the width of the light guiding region gradually increases from the incident end along the light propagation direction; and when viewed from the side, the width of the light guiding region gradually decreases from the top to the bottom; or, the interface between the light guiding region and the waveguide layer is fan-shaped; and / or, the cross-section of the light absorption region 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 this invention are as follows:

[0038] To address the need for frequent millisecond-level switching in deep learning training scenarios, this application provides a high-response computing array with a thermal compensation mechanism that can reduce light reflection, thereby achieving the design of a low-power, large-scale integrated computing array while meeting the requirements of frequent switching.

[0039] In contrast to existing methods that use phase change materials for modulation or change the carrier concentration by injecting current or applying voltage within the dopant to alter the light absorption coefficient, this application provides an optical computing array based on a reverse-biased germanium modulator, while simultaneously employing a scheme that allows for multiple modulations of the light absorption characteristics of the germanium absorption layer.

[0040] First, this application modulates the photoresponsivity of the germanium modulator by voltage regulation. The dark current of the germanium modulator under reverse bias is extremely low, and its photocurrent during operation is at least two orders of magnitude smaller than that of forward-conducting carrier absorption modulators or phase change material modulators, 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, along with a real-time feedback mechanism, to ensure the temperature consistency and uniformity of the entire germanium absorption layer. This increases the number of valence band electrons that can transition, thereby changing the light absorption coefficient of the germanium absorption layer while reducing the operating voltage of the electroabsorption modulator. Moreover, when anomalies such as signal distortion caused by temperature (e.g., high system temperature due to high system power consumption, or high temperature during the modulation process of the heating unit) are detected, temperature compensation can be performed using the heating unit located inside the optical computing array, eliminating the need for a separate temperature compensation module outside the optical computing array. In other words, by setting up a dual-purpose heating unit, both the light absorption coefficient of the absorption layer and its temperature can be compensated to alleviate signal distortion.

[0042] Furthermore, for cases where the light absorption cross-sectional area of ​​the light absorption region (germanium absorption layer) is large (e.g., "full etching"), this application designs the germanium absorption layer into partitions (light guiding region and light absorption region). The light signal transmitted from the optical waveguide is guided by a gradient interface formed by the gradual change in the height and width of the light guiding region. This means that the cross-sectional area of ​​the light guiding region gradually increases from the incident end in both height and length, which can significantly 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. Attached Figure Description

[0043] 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.

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

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

[0046] Figure 3This is another exemplary side view of the modulator in Embodiment 2 of the present invention;

[0047] Figure 4 This is a top view of the modulator in Embodiment 2 of the present invention;

[0048] Figure 5 This is a front view of the germanium absorption layer in Embodiment 2 of the present invention;

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

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

[0051] Figure 8 This is a schematic diagram of the structure of another exemplary optical computing array in Embodiment 1 of the present invention.

[0052] The diagram is labeled as follows: 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 strip; 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 Implementation

[0053] 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.

[0054] In this document, suffixes such as "module," "component," or "unit" used to denote elements are used solely for the purpose of illustrative purposes and have no specific meaning in themselves. Therefore, "module," "component," or "unit" may be used interchangeably. In this document, terms such as "upper," "lower," "inner," "outer," "front," "rear," "one end," and "the other end," indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the 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, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0055] In this document, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," and "connected," etc., should be interpreted broadly. For example, "connected" 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. In this document, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0056] In this paper, the "splitter" can utilize components such as optical waveguides, optical couplers, heaters, and phase shifters with specific structures to distribute optical signals within the chip in an active or passive manner. Correspondingly, the "combiner" can utilize components such as optical waveguides, optical couplers, heaters, and phase shifters with specific structures to sum optical signals within the chip in an active or passive manner.

[0057] Example 1

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

[0059] The cross matrix is ​​formed by multiple rows of parallel input channels and multiple columns of parallel output channels, and each column of the output waveguide is equipped with a photodetector at its output end.

[0060] Multiple beam splitters are provided, wherein the beam splitters are positioned at the front end of the cross channel formed by each row of optical input channels and each column of output channels.

[0061] Multiple signal processing units are provided, each signal processing unit corresponding to one of the cross channels, and the first input terminal of each signal processing unit is connected to the output terminal of the beam splitter via a transmission optical waveguide; the transmission optical waveguide may be selected from 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 higher 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 beam combiners are provided, each of which is connected to the output terminal 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 to existing methods that use phase change materials for modulation or alter carrier concentration by injecting current or applying voltage within the dopant to change the light absorption coefficient, this application proposes a radically different solution for the millisecond-level frequent switching requirements in deep learning training scenarios. This application provides an optical computing array based on a reverse-biased germanium modulator. By controlling the photoresponsivity of the germanium modulator with voltage, the dark current of the germanium modulator under reverse bias is extremely low. Its photocurrent during operation is at least two orders of magnitude smaller than that of forward-conducting carrier absorption modulators or phase change material modulators, 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 correspondingly, the signal processing unit is a germanium modulator.

[0066] Specifically, the optical computing array includes:

[0067] The cross matrix is ​​formed by multiple rows of parallel input optical waveguides and multiple columns of parallel output optical waveguides; and each column of output optical waveguides is provided with a photodetector at its output end; preferably, the input optical waveguides and the output optical waveguides are arranged perpendicularly.

[0068] Multiple optical splitters are provided, wherein the optical splitters are disposed at the front end of the cross waveguide formed by each row of input optical waveguides and each column of output optical waveguides; preferably, the optical splitters are disposed at the front end of the input optical waveguides in the cross waveguides.

[0069] Multiple germanium modulators, each of the germanium modulators corresponding to one of the cross waveguides, and the first input terminal of the germanium modulator is connected to the output terminal of the beam splitter via a transmission optical waveguide;

[0070] Multiple optical combiners are provided, each of which is connected to the output terminal of the germanium modulator and the output optical waveguide, respectively, for combining 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 transmitting it to the next cross waveguide on the same output optical waveguide;

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

[0072] In other words, multiple rows of input optical waveguides and multiple rows of output optical waveguides are cross-arranged to divide the optical computing array into multiple optical computing units. The optical computing unit includes cross waveguides and beam splitters, germanium modulators and beam combiners arranged at different positions on the cross waveguides.

[0073] In other embodiments, the input channel is an input optical waveguide, the output channel is an electrical bus, and correspondingly, the signal processing unit is a germanium modulator and a photodetector (i.e., the first photodetector mentioned below).

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

[0075] Multiple optical splitters are disposed at the front end of the intersection node of each row of optical input waveguides and each column of electrical bus; preferably, the optical splitters are disposed at the front end of the input optical waveguides in the intersection waveguides.

[0076] Multiple germanium modulators, each of the germanium modulators corresponding to one of the cross nodes, and the first input terminal of the germanium modulator is connected to the output terminal of the beam splitter via a transmission optical waveguide;

[0077] Multiple first photodetectors are provided, each of which is connected to the output terminal of the germanium modulator and the electrical bus, respectively, for converting the optical signal output by the germanium modulator into an electrical signal and sending it to the electrical bus;

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

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

[0080] In other words, 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. The optical computing unit includes cross-waveguides and beam splitters, germanium modulators, first photodetectors and beam combiners arranged at different positions on the cross-waveguides.

[0081] Example 2

[0082] This embodiment provides a germanium modulator applied to the optical computing array in Embodiment 1, including a silicon substrate 1 and an insulating layer 4 deposited on the silicon substrate 1; a waveguide layer 2 is disposed on the insulating layer 4; a germanium absorption layer 5 is embedded in the waveguide layer 2; the first depth of the germanium absorption layer 5 embedded in the waveguide layer 2 is less than the thickness of the waveguide layer 2, or the second depth of the germanium absorption layer 5 embedded in the waveguide layer 2 is 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, which is "full etching").

[0083] Specifically, 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 embodiments, when the second depth is equal to the thickness of the waveguide layer 2, that is, with the insulating layer 4 as the etching endpoint, on the one hand, the germanium absorption layer 5 can have a larger cross-section, thereby maximizing the overlap time between the modulation region and the optical field. For the same length, the responsivity is higher; for the same responsivity, the size is smallest. On the other hand, the etching depth is easier to control, ensuring the consistency of the etching trench depth between different modulators. In traditional shallow etching processes, due to the shallow etching depth and difficulty in precise control, it is easily affected by factors such as uneven silicon layer thickness, leading to inconsistent etching depths and thus affecting the performance uniformity of the modulator. The etching trench process reaching the insulating layer 4 has better stability and is beneficial for 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, heating units 3 are provided at the top and / or bottom of the germanium absorption layer 5, and the heating units 3 extend along the length direction of the germanium absorption layer 5; or, heating units 3 are 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, heating unit groups 3 are provided on both sides of the germanium absorption layer 5, and each heating unit group 3 includes multiple 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 on the same side are primary heating and secondary heating, respectively; the heating units 3 are used to change the photoelectric properties of the light absorption layer.

[0087] Unlike the traditional approach of relying on high electric field strength to increase the absorption coefficient and thus ensure the uniformity of photocurrent density, this invention provides a thermal compensation mechanism that only targets the endpoint effect. Specifically, by setting 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 of the germanium absorption layer, ensuring the consistency and uniformity of the temperature of the entire germanium absorption layer 5, thereby increasing the number of valence band electrons that can jump, thereby changing the light absorption coefficient of the germanium absorption layer 5 while reducing the operating voltage of the electroabsorption modulator. In this process, it is only necessary to ensure the final light absorption rate (i.e., 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, this application provides a thermal compensation mechanism that dually regulates the light absorption coefficient, targeting only the endpoint effect. First, the light absorption coefficient of the germanium absorption layer is adjusted from the germanium modulator itself by heating the germanium absorption layer. Then, the light absorption coefficient of the germanium absorption layer is further adjusted by adjusting the input voltage. That is to say, the adjustment requirements of the input voltage in this process are not high. In other words, the response speed of the computing array can be guaranteed while ensuring low energy consumption, thereby meeting the requirements of large-scale matrices.

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

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

[0091] The first judgment module is used to determine whether the actual temperature value monitored by the temperature monitoring module is greater than a first preset temperature threshold. If the actual temperature value is greater than the first preset temperature threshold, a first control signal indicating that heating has stopped is generated and sent to the heating unit 3 / the heating unit group; if the actual temperature value is less than the first preset temperature threshold, a second control signal indicating that monitoring continues is generated and sent 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 with a heating level of Level 1.

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

[0094] The first temperature threshold can be obtained in advance through a large number of experiments, or it can be preset 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 effect on the material itself.

[0095] The division of heating levels (Level 1 and Level 2) is only for the purpose of distinguishing between the two and does not limit their heating power or other characteristics. When only Level 1 heating is turned on, the heating power is relatively small, while when both Level 1 and Level 2 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] This 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 valence band electrons that can transition. 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 temperature changes.

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

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

[0099] When viewed from above, the width of the light guiding region gradually increases from the incident end along the light propagation direction; and when viewed from the side, the width of the light guiding region gradually decreases from the top to the bottom; or, the interface between the light guiding region and the waveguide layer is fan-shaped; and / or, the cross-section of the light absorption region 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 at the interface of media with different refractive indices, the greater the difference in refractive index, the more severe the reflection. This gradual transition structure allows light to enter the germanium absorption layer 5 more smoothly from the silicon waveguide, improving the coupling efficiency and thus enhancing the modulator's absorption capability.

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

[0102] Due to technological limitations, a conical light guiding region requires significant cost. Therefore, in this embodiment, to reduce manufacturing complexity, the cross-sectional area of ​​the light guiding region only needs to gradually increase from the incident end along the direction close to the light absorption region 52. For example, the light guiding region is a triangle that is narrower at the front and wider at the back when viewed from above, and a trapezoid that is larger at the top and smaller at the bottom when viewed from the front. Although it differs from an ideal conical shape, the trapezoidal structure can still achieve a gradual change in refractive index to a certain extent, reducing light reflection, and is a feasible solution under existing technological conditions.

[0103] In other words, by restricting the shape of the light guiding region, the cross-sectional area of ​​the light guiding region gradually increases from the incident end in both height and length. This can significantly 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, this application provides a full etching scheme 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. This ensures heating effectiveness without unnecessary heat waste. In this embodiment, the addition of the germanium absorption layer with the above-described structure improves light absorption efficiency. However, it also amplifies any data anomalies, such as data distortion, making it easier to detect anomalies in subsequent processes. There are various factors that can cause data anomalies, and specific judgment and identification mechanisms can be used with existing technologies, which will not be elaborated here. Once an anomaly such as data distortion caused by temperature is identified, temperature compensation can be performed through the heating unit.

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

[0106] In contrast to existing methods that use phase change materials for modulation or change the carrier concentration by injecting current or applying voltage within the dopant to alter the light absorption coefficient, this application provides an optical computing array based on a reverse-biased germanium modulator, while simultaneously employing a scheme that allows for multiple modulations of the light absorption characteristics of the germanium absorption layer.

[0107] First, this application modulates the photoresponsivity of the germanium modulator by voltage regulation. The dark current of the germanium modulator under reverse bias is extremely low, and its photocurrent during operation is at least two orders of magnitude smaller than that of forward-conducting carrier absorption modulators or phase change material modulators, 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 used to ensure the consistency and uniformity of the temperature of the entire germanium absorption layer 5, thereby increasing the number of valence band electrons that can jump, thereby changing the light absorption coefficient of the germanium absorption layer 5 while reducing the operating voltage of the electroabsorption modulator.

[0109] Furthermore, for cases where the light absorption cross-sectional area of ​​the light absorption region (germanium absorption layer) is large (e.g., "full etching"), this application designs the germanium absorption layer into partitions (light guiding region and light absorption region). The light signal transmitted from the optical waveguide is guided by a gradient interface formed by the gradual change in the height and width of the light guiding region. This means that the cross-sectional area of ​​the light guiding region gradually increases from the incident end in both height and length, which can significantly 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.

[0110] 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.

[0111] 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. An optical computing array based on reverse-biased germanium modulators, characterized in that, The application relates to a cross-matrix formed by a plurality of rows of parallel input optical waveguides and a plurality of columns of parallel output optical waveguides. A plurality of optical splitters are arranged at the front end of the cross waveguide formed by each row of input optical waveguides and each column of output optical waveguides. A plurality of germanium modulators are provided, each corresponding to one cross waveguide, and the first input end of the germanium modulator is connected to the output end of the optical splitter through a transmission optical waveguide. A plurality of optical combiners are connected to the output end of the germanium modulator and the output optical waveguide respectively, and are used for combining 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 transmitting the third optical signal to the next cross waveguide on the same output optical waveguide. The photoelectric property of the light absorption layer in the germanium modulator can be changed by the control signal input through the second input end, and the germanium modulator can generate the second optical signal based on the first optical signal input through the first input end and send the second optical signal to the optical combiner; the photoelectric property includes the light absorption coefficient. The germanium modulator comprises a silicon substrate and an insulating layer deposited on the silicon substrate; a waveguide layer is arranged on the insulating layer; and a germanium absorption layer is embedded in the waveguide layer. At least one side of the germanium absorption layer is provided with a heating unit; the heating unit is used for changing the photoelectric property of the light absorption layer. The germanium absorption layer comprises a light guiding area and a light absorption area arranged in sequence along the light propagation direction, wherein the cross-sectional area of the light guiding area gradually increases along the direction close to the light absorption area from the incident end; and the cross-sectional area of the light absorption area is the same along the light propagation direction. The heating unit is arranged at 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 The heating unit is arranged at the two sides of the germanium absorption layer, and the heating unit extends along the length direction of the germanium absorption layer; or The two sides of the germanium absorption layer are respectively provided with a heating unit group, and each heating unit group on the side comprises a plurality of heating units uniformly and spacedly arranged along the length direction of the germanium absorption layer, wherein the heating levels of the adjacent two heating units on the same side are first heating and second heating respectively. The germanium modulator further comprises: A temperature monitoring module is used for monitoring the actual temperature value of the germanium absorption layer in real time. A first judging module is used for judging whether the actual temperature value monitored by the temperature monitoring module is greater than a first preset temperature threshold value; if the actual temperature value is greater than the first preset temperature threshold value, a first control signal representing stopping heating is generated and sent to the heating unit or the heating unit group; if the actual temperature value is less than the first preset temperature threshold value, a second control signal representing continuing monitoring is generated and sent to the temperature monitoring module. Or, the temperature monitoring module is used for monitoring the actual temperature value of the germanium absorption layer after the heating unit with the first heating level and in the heating state is heated in real time. ​ The second judging module is configured to judge whether the actual temperature value monitored by the temperature monitoring module reaches a preset target temperature threshold after a preset time length, and if not, generate and send a third control signal representing a heating unit in a sleep state with a second heating level started, so that the actual temperature of the germanium absorption layer reaches the preset target temperature threshold.

2. The reverse-biased germanium modulator-based optical computing array of claim 1, wherein, The first depth of the germanium absorption layer embedded in the waveguide layer is less than the thickness of the waveguide layer, or the second depth of the germanium absorption layer embedded in the waveguide layer is equal to the thickness of the waveguide layer.

3. The reverse-biased germanium modulator-based optical computing array of claim 1, wherein, The width of the light guiding area gradually increases along the light propagation direction from the incident end when viewed from the top, and the width of the light guiding area gradually decreases from the top to the bottom when viewed from the side.

4. The reverse-biased germanium modulator-based optical computing array of claim 1, wherein, The width and length of the heating unit located at the top and / or bottom of the germanium absorption layer are less than the width and length of the germanium absorption layer.

5. The reverse-biased germanium modulator-based optical computing array of claim 1, wherein, The input optical waveguide and the output optical waveguide are arranged vertically.

6. The reverse-biased germanium modulator-based optical computing array of claim 1, wherein, The longitudinal section of the light guiding area is a right-angled trapezoid, and the hypotenuse of the right-angled trapezoid corresponds to the interface between the light guiding area and the waveguide layer, and the included angle α between the hypotenuse and the bottom side is 86°-89°.

7. The reverse-biased germanium modulator-based optical computing array of claim 1, wherein: The interface between the light guiding area and the waveguide layer is in the shape of a sector, and the longitudinal section of the light absorbing area is in the shape of a rectangle.

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