Optical calculation array based on micro-ring resonators without free spectral range

Abstract

The invention discloses an optical computing array based on micro-ring resonators without a free spectral range, which comprises an on-chip wavelength division multiplexing beam splitting array, an on-chip intensity modulation array, two groups of on-chip wavelength division multiplexing beam combining arrays and an on-chip balance detector, the on-chip wavelength division multiplexing beam splitting array and the on-chip wavelength division multiplexing beam combining array are respectively composed of a group of multiple FSR-free MRRs which share the same bus optical waveguide, each resonator corresponds to an independent wavelength channel, and the on-chip intensity modulator array is composed of a plurality of groups of on-chip MZI modulator arrays. According to the optical calculation array implementation method, independent control and coding calculation of different wavelength channels in a broadband wavelength range are realized by utilizing the single harmonic peak characteristic of the FSR-free MRR array and the wide-spectrum intensity modulation function of the MZI unit, the limitation of a free spectrum range on the optical calculation wavelength channel is eliminated, the higher wavelength parallelism is achieved, and the optical calculation array implementation method has the advantages of being simple in structure and convenient to implement. And therefore, the calculation scale is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of silicon-based optical computing, and more specifically, to an optical computing array based on a microring resonator with no free spectral range. Background Technology

[0002] As an emerging computing paradigm, silicon-based optical computing technology has attracted widespread attention due to its advantages such as low latency, low power consumption, and high parallelism, demonstrating enormous application potential in fields such as artificial intelligence and signal processing. In current development implementations, silicon-based optical computing schemes based on wavelength division multiplexing (WDM) architectures utilize the inherent parallel dimension of wavelength in optical signals for information mapping and computation, achieving high-throughput data processing capabilities and providing the necessary computing power support for the aforementioned application areas.

[0003] Currently, silicon-based optical computing based on wavelength division multiplexing (WDM) architectures typically employs wavelength-selective devices such as microring resonators and their arrays to achieve independent intensity modulation of optical signals in different wavelength channels within the WDM signal, thus mapping between numerical domain computation and optical domain signals. However, due to the periodic resonant characteristics of these devices across the spectral range, the independently controllable wavelength channels used by the same WDM computing array are often limited to a single free spectral range of the device. While optimizing the performance of individual devices, such as the quality factor, or increasing the wavelength density of the WDM light source can improve the computational density within a single free spectral range, the resulting increase in hardware complexity and system control precision becomes an obstacle to practical implementation. This contradiction becomes even more apparent during large-scale integration.

[0004] Therefore, a new hardware implementation scheme is urgently needed to address the limitations of wavelength division multiplexing optical computing architecture in terms of wavelength parallelism. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an optical computing array based on a micro-ring resonator without a free spectral range, starting from the hardware device and array design for realizing computing functions. This aims to overcome the limitation of the free spectral range of traditional wavelength-selective devices on the parallelism of wavelength division multiplexing optical computing schemes, and realize a silicon-based optical computing hardware architecture with high parallelism and high wavelength channel capacity.

[0006] The above-mentioned technical objective of this invention is achieved through the following technical solution: an optical computing array based on a microring resonator without a free spectral range, the array comprising an on-chip wavelength division multiplexing beam splitter array, an on-chip intensity modulation array, two sets of on-chip wavelength division multiplexing beam combiner arrays, and an on-chip balanced detector, wherein, The on-chip wavelength division multiplexing beam splitter array consists of multiple FSR-free MRRs that share the same bus optical waveguide, with each resonator corresponding to an independent wavelength channel. The on-chip intensity modulator array consists of multiple on-chip Mach-Zehnder interferometer (MZI) modulator arrays, the number of which is the same as the wavelength channels used to perform the calculations, and each group contains two MZI modulator units in series. The on-chip wavelength division multiplexing beam combiner array consists of multiple FSR-free MRRs that share the same bus optical waveguide, with each resonator corresponding to an independent wavelength channel. The on-chip balanced detector consists of two on-chip photodetectors, which are respectively connected to the output terminals of the two bus waveguides of the on-chip wavelength division multiplexing beam combiner array, and convert the difference in optical power output by the two into photocurrent output.

[0007] Furthermore, the on-chip wavelength division multiplexing beam splitter array performs on-chip beam splitting on the wavelength division multiplexing optical signal input to the structure. Each FSR-free MRR in the array structure selectively downloads its corresponding wavelength signal in the bus waveguide to its respective transmission channel and transmits it forward.

[0008] Furthermore, in the on-chip intensity modulator array, each channel is connected in series with a 1×1 active high-speed MZI modulator and a 1×2 thermo-optical MZI modulator; wherein, the input port of the 1×1 active high-speed MZI modulator is connected to the download end of the corresponding FSR-free MRR in the on-chip wavelength division multiplexing beam splitting array, and its output port is connected to the input end of the 1×2 thermo-optical MZI modulator, and the two output ports of the 1×2 thermo-optical MZI modulator are respectively connected to the input ends of the two corresponding FSR-free MRRs in the on-chip wavelength division multiplexing beam combining array.

[0009] Furthermore, the two sets of on-chip wavelength division multiplexing beam combining arrays correspond to the two output ports of each 1×2 thermo-optical MZI modulator in the on-chip intensity modulator array; the input port of each FSR-free MRR contained in the first set of wavelength division multiplexing beam combining arrays is connected to the first output port of each 1×2 thermo-optical MZI modulator, for downloading and combining the specific wavelength optical signal output from the output port to its bus waveguide; the input port of each FSR-free MRR contained in the second set of wavelength division multiplexing beam combining arrays is connected to the second output port of each 1×2 thermo-optical MZI modulator, for downloading and combining the specific wavelength optical signal output from the output port to its bus waveguide.

[0010] Furthermore, the up-and-down microring resonator comprises an up-and-down microring resonator as the main structure, two racetrack-shaped directional couplers with Bragg gratings as the coupling region, and three thermo-optical phase shifters, wherein... The ring waveguide of the microring resonator has a different waveguide width from the bus waveguide, which suppresses the positive resonance of the microring resonator. The Bragg grating-assisted racetrack-shaped directional coupler introduces a reverse optical signal loop with bandpass filtering properties and completes reverse resonance within the micro-ring resonator. The three thermo-optical phase shifters are located above the up-down micro-ring resonator and the two Bragg grating-assisted racetrack-shaped directional couplers, respectively. Specifically, by controlling the thermo-optical phase shifter, the reverse resonance spectrum of the micro-ring resonator and the bandpass filter spectrum of the Bragg grating-assisted racetrack-type directional coupler can be red-shifted or blue-shifted. Then, by superimposing the three resonance spectrum lines, a single resonance peak in the spectral range is achieved, eliminating the influence of FSR. Thus, the FSR-free MRR can only perform routing function for optical signals of a single wavelength channel without interfering with other wavelength channels.

[0011] Furthermore, for a single element in the input vector corresponding to the 1×1 active high-speed MZI modulator in its array, for a non-negative input vector with the same number of dimensions as the number of channels in the on-chip intensity modulator array, by rapidly switching the operating state of each 1×1 active high-speed MZI modulator, the element (x) in each of the different input vectors... i (where i is the dimension of the element in the vector) is quickly encoded and mapped to the optical power of each beam of light passing through the modulator. , (Input the optical signal power of the i-th 1×1 active high-speed MZI modulator) to complete high-throughput signal encoding.

[0012] Furthermore, for a single element in the weight vector corresponding to the 1×2 thermo-optical MZI modulator in its array, for a weight vector with the same number of dimensions as the number of channels in the on-chip intensity modulator array, by controlling the operating state of each 1×2 thermo-optical MZI modulator, the normalized element (w) of each weight vector... i The difference in optical power between the two output ports of the thermo-optical MZI modulator, where i is the dimension of the element in the vector, is encoded and mapped to represent the splitting ratio of each real element (where i is the dimension of the element in the vector). , (where is the splitting ratio of the i-th thermo-optical MZI modulator); for an optical signal carrying input vector elements input to a 1×2 thermo-optical MZI modulator, after passing through the thermo-optical MZI modulator, it is split into two optical signals (with optical powers respectively). and It then passes the signal to the next level on-chip wavelength division multiplexing beam combiner array.

[0013] Furthermore, both the 1×1 active high-speed MZI modulator and the 1×2 thermo-optical MZI modulator are configured as equal-arm MZI structures, and their broadband operating characteristics do not introduce additional wavelength-dependent crosstalk during input encoding and weight encoding.

[0014] Furthermore, the two photodetectors in the on-chip balanced detector are respectively connected to the bus waveguide output ports of the two sets of on-chip wavelength division multiplexing beam combiner arrays, and convert the wavelength division multiplexed optical signals after beam combining in the two waveguides into photocurrents (current values ​​are respectively...). and , The corresponding coefficients of the on-chip photodetector), and its final output differential current is characterized by the calculated result (differential current value). ).

[0015] In summary, the present invention has the following beneficial effects: The optical computing array based on a free-spectrum-range microring resonator disclosed herein utilizes the single resonant peak characteristics of the FSR-freeMRR array and the broadband intensity modulation function of the MZI unit to achieve independent control and encoding calculation of different wavelength channels within a broadband wavelength range. This eliminates the limitation of the free spectrum range on the optical computing wavelength channels, resulting in higher wavelength parallelism and a significant improvement in its computing scale. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an optical computing array based on a microring resonator without a free spectral range according to the present invention; Figure 2 This is a schematic diagram of a microring resonator without free spectral range used in the wavelength division multiplexing beam splitter / combiner array of the present invention; Figure 3 The uploading and downloading type micro-ring resonator in this invention ( Figure 3 (a) Solid line), Bragg grating-assisted racetrack-type directional coupler ( Figure 3 (a) Dashed line), FSR-free MRR ( Figure 3 (b) Amplitude-frequency response curve; Figure 4 This is a schematic diagram of a series MZI modulator used in the intensity modulator array of the present invention; Figure 5 This is a schematic diagram of the on-chip balanced detector used in this invention. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] In the preferred embodiments of the present invention, those skilled in the art should note that MZI and the like involved in the present invention can be considered as prior art.

[0019] Example 1, as Figure 1 As shown, the architecture includes an on-chip wavelength division multiplexing beam splitter array, an on-chip intensity modulation array, two sets of on-chip wavelength division multiplexing beam combiner arrays, and an on-chip balanced detector. The on-chip wavelength division multiplexing beam splitter array consists of multiple FSR-free MRRs that share the same bus optical waveguide, with each resonator corresponding to an independent wavelength channel. The on-chip intensity modulator array consists of multiple on-chip Mach-Zehnder interferometer (MZI) modulator arrays, the number of which is the same as the wavelength channels used to perform the calculations, with each group containing two MZI modulator units in series. The on-chip wavelength division multiplexing beam combiner array consists of multiple FSR-free MRRs that share the same bus optical waveguide, with each resonator corresponding to an independent wavelength channel. The on-chip balanced detector consists of two on-chip photodetectors, which are respectively connected to the output terminals of the two bus waveguides of the on-chip wavelength division multiplexing beam combiner array, and convert the difference in optical power output between the two into photocurrent output.

[0020] The on-chip wavelength division multiplexing beam splitter array performs on-chip beam splitting of the wavelength division multiplexing optical signal input to the structure. Each FSR-free MRR in the array structure selectively downloads the corresponding wavelength signal in the bus waveguide to its respective transmission channel and transmits it forward.

[0021] In the on-chip intensity modulator array, each channel is connected in series with a 1×1 active high-speed MZI modulator and a 1×2 thermo-optical MZI modulator. The input port of the 1×1 active high-speed MZI modulator is connected to the download port of the corresponding FSR-free MRR in the on-chip wavelength division multiplexing beam splitter array, and its output port is connected to the input port of the 1×2 thermo-optical MZI modulator. The two output ports of the 1×2 thermo-optical MZI modulator are respectively connected to the input ports of the two corresponding FSR-free MRRs in the on-chip wavelength division multiplexing beam combiner array.

[0022] Two sets of on-chip wavelength division multiplexing beam combiner arrays correspond to the two output ports of each 1×2 thermo-optical MZI modulator in the on-chip intensity modulator array, respectively. The input port of each FSR-free MRR contained in the first set of wavelength division multiplexing beam combiner arrays is connected to the first output port of each 1×2 thermo-optical MZI modulator, and is used to download and combine the specific wavelength optical signal output from the output port to its bus waveguide. The input port of each FSR-free MRR contained in the second set of wavelength division multiplexing beam combiner arrays is connected to the second output port of each 1×2 thermo-optical MZI modulator, and is used to download and combine the specific wavelength optical signal output from the output port to its bus waveguide.

[0023] like Figure 2As shown, the uploading / downloading microring resonator includes an uploading / downloading microring resonator 1 as the main structure, two racetrack-shaped directional couplers 2 and 3 with Bragg gratings as the coupling region, and three thermo-optical phase shifters. The ring waveguide and the bus waveguide of the microring resonator have different waveguide widths, which suppresses the positive resonance of the microring resonator. The Bragg grating-assisted racetrack-shaped directional coupler introduces a reverse optical signal loop with bandpass filtering properties and completes reverse resonance within the microring resonator; Three thermo-optical phase shifters are located above the upper and lower download type micro-ring resonator and two Bragg grating-assisted racetrack-shaped directional couplers 1-3, respectively; Among them, by controlling the thermo-optical phase shifter, the inverse resonance spectrum of the micro-ring resonator and the bandpass filter spectrum of the Bragg grating-assisted racetrack-type directional coupler can be red-shifted or blue-shifted, thereby enabling the resonance spectrum of the three elements to be displayed as follows: Figure 3 The forms in (a) are superimposed to achieve the following: Figure 3 (b) shows a single resonant peak in the spectral range, eliminating the influence of FSR, so that FSR-free MRR can perform routing function only for optical signals of a single wavelength channel without interfering with other wavelength channels.

[0024] Each channel in the on-chip intensity modulator array is connected in series with an MZI modulation unit, such as... Figure 4 As shown, the structure consists of four 50:50 on-chip optical beam splitters 4, an on-chip active phase shifter 5, and thermo-optical phase shifters 6-7. The 1×1 active high-speed MZI modulator corresponds to a single element in the input vector. For a non-negative input vector with the same dimension as the number of channels in the on-chip intensity modulator array, the high-speed control of the active phase shifter 5 enables the switching of the 1×1 active high-speed MZI modulator's operating state. This allows each element (xi, where i is the dimension of the element in the vector) in different input vectors to be quickly encoded and mapped to the optical power of each beam of light passing through the modulator. , (To input the optical signal power of the i-th 1×1 active high-speed MZI modulator), complete the high-throughput signal encoding, and the thermo-optical phase shifter 6 is used to adjust the initial operating state of the 1×1 active high-speed MZI modulator.

[0025] In the array, each element of the weight vector corresponding to a 1×2 thermo-optical MZI modulator is assigned a dimension equal to the number of channels in the on-chip intensity modulator array. The operating state of each 1×2 thermo-optical MZI modulator is configured by controlling the thermo-optical phase shifter 7. Each normalized element of the weight vector (wi, where i is the dimension of the element in the vector) is encoded and mapped to the splitting ratio of the thermo-optical MZI modulator. The difference in optical power between the two output ports characterizes each real element ( , (where is the splitting ratio of the i-th thermo-optical MZI modulator); for an optical signal carrying input vector elements input to a 1×2 thermo-optical MZI modulator, after passing through the thermo-optical MZI modulator, it is split into two optical signals (with optical powers respectively). and It then passes the signal to the next level on-chip wavelength division multiplexing beam combiner array.

[0026] Both the 1×1 active high-speed MZI modulator and the 1×2 thermo-optical MZI modulator are configured as equal-arm MZI structures, and their broadband operating characteristics do not introduce additional wavelength-dependent crosstalk during input encoding and weight encoding.

[0027] like Figure 5 As shown, the bus waveguide output ports 8-9 of the two sets of on-chip wavelength division multiplexing beam combiner arrays output the beam-combined wavelength division multiplexed optical signals, with powers of respectively. and It is connected to two photodetectors 10-11 in the on-chip balanced detector, and the two wavelength division multiplexed optical signals are thus converted into photocurrent values ​​of respectively. and The photocurrent, of which Given the corresponding coefficients of the on-chip photodetector, the final output of the balanced detector is the differential current of the two photogenerated currents mentioned above. This output current is numerically equivalent to the input vector. and weight vector The result of calculating the vector dot product.

[0028] The optical computing array based on a free-spectrum-range microring resonator provided in this embodiment utilizes the single resonant peak characteristic of the FSR-free MRR array and the broadband intensity modulation function of the MZI unit to achieve independent control and encoding calculation of different wavelength channels within a broadband wavelength range. This eliminates the limitation of the free spectrum range on the optical computing wavelength channels, has higher wavelength parallelism, and thus achieves a significant improvement in its computing scale.

[0029] It should be understood that the optical computing arrays of this disclosure can be implemented with larger-scale array combinations. In the above embodiments, oriented towards the input vector and weight vector The vector dot product calculation form and its array can be further generalized to higher-dimensional linear calculation forms of the same type by increasing the number of on-chip FSR-free MRR units and MZI modulator units in the topological cascade, such as input vectors. and weight vector The matrix-vector multiplication calculation form. By utilizing the FSR-free MRR array in this invention to realize the beam splitting / combining function of wavelength division multiplexing signals, and by utilizing the MZI modulator unit and its array to realize the on-chip optical computing array form for linear weight calculation of optical signals of different wavelength channels, this should be regarded as the inventive point of this invention.

[0030] It is worth mentioning that the technical features such as MZI involved in this patent application should be regarded as prior art. The specific structure, working principle and possible control methods and spatial arrangement of these technical features can be adopted using conventional choices in the field, and should not be regarded as the inventive point of this patent. This patent will not be further elaborated in detail.

[0031] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An optical computing array based on a microring resonator without a free spectral range, characterized in that: The array comprises an on-chip wavelength division multiplexing beam splitter array, an on-chip intensity modulation array, two sets of on-chip wavelength division multiplexing beam combiner arrays, and an on-chip balanced detector. The on-chip wavelength division multiplexing beam splitter array consists of multiple FSR-free MRRs that share the same bus optical waveguide, with each resonator corresponding to an independent wavelength channel. The on-chip intensity modulator array consists of multiple on-chip Mach-Zehnder interferometer (MZI) modulator arrays, the number of which is the same as the wavelength channels used to perform the calculations, and each group contains two MZI modulator units in series. The on-chip wavelength division multiplexing beam combiner array consists of multiple FSR-free MRRs that share the same bus optical waveguide, with each resonator corresponding to an independent wavelength channel. The on-chip balanced detector consists of two on-chip photodetectors, which are respectively connected to the output terminals of the two bus waveguides of the on-chip wavelength division multiplexing beam combiner array, and convert the difference in optical power output by the two into photocurrent output.

2. The optical computing array based on a microring resonator without a free spectral range according to claim 1, characterized in that: The on-chip wavelength division multiplexing beam splitter array performs on-chip beam splitting of the wavelength division multiplexing optical signal input to the structure. Each FSR-free MRR in the array structure selectively downloads its corresponding wavelength signal in the bus waveguide to its respective transmission channel and transmits it forward.

3. The optical computing array based on a microring resonator without a free spectral range according to claim 1, characterized in that: In the on-chip intensity modulator array, each channel is connected in series with a 1×1 active high-speed MZI modulator and a 1×2 thermo-optical MZI modulator. The input port of the 1×1 active high-speed MZI modulator is connected to the download port of the corresponding FSR-free MRR in the on-chip wavelength division multiplexing beam splitter array, and its output port is connected to the input port of the 1×2 thermo-optical MZI modulator. The two output ports of the 1×2 thermo-optical MZI modulator are respectively connected to the input ports of the two corresponding FSR-free MRRs in the on-chip wavelength division multiplexing beam combiner array.

4. The optical computing array based on a microring resonator without a free spectral range according to claim 1, characterized in that: The two sets of on-chip wavelength division multiplexing beam combining arrays correspond to the two output ports of each 1×2 thermo-optical MZI modulator in the on-chip intensity modulator array; the input port of each FSR-free MRR contained in the first set of wavelength division multiplexing beam combining arrays is connected to the first output port of each 1×2 thermo-optical MZI modulator, and is used to download and combine the specific wavelength optical signal output from the output port to its bus waveguide; The input ports of each FSR-free MRR contained in the second group of wavelength division multiplexing beamforming array are connected to the second output port of each of the 1×2 thermo-optical MZI modulators, for downloading and beamforming specific wavelength optical signals output from the output port to its bus waveguide.

5. An optical computing array based on a microring resonator without a free spectral range, as described in claim 2 or 4, characterized in that: The uploading / downloading microring resonator comprises an uploading / downloading microring resonator as the main structure, two racetrack-shaped directional couplers with Bragg grating assistance as the coupling region, and three thermo-optical phase shifters, wherein... The ring waveguide of the microring resonator has a different waveguide width from the bus waveguide, which suppresses the positive resonance of the microring resonator. The Bragg grating-assisted racetrack-shaped directional coupler introduces a reverse optical signal loop with bandpass filtering properties and completes reverse resonance within the micro-ring resonator. The three thermo-optical phase shifters are located above the up-down micro-ring resonator and the two Bragg grating-assisted racetrack-shaped directional couplers, respectively. Specifically, by controlling the thermo-optical phase shifter, the reverse resonance spectrum of the micro-ring resonator and the bandpass filter spectrum of the Bragg grating-assisted racetrack-type directional coupler can be red-shifted or blue-shifted. Then, by superimposing the three resonance spectrum lines, a single resonance peak in the spectral range is achieved, eliminating the influence of FSR. Thus, the FSR-free MRR can only perform routing function for optical signals of a single wavelength channel without interfering with other wavelength channels.

6. The optical computing array based on a microring resonator without a free spectral range according to claim 3, characterized in that: The 1×1 active high-speed MZI modulator in the array corresponds to a single element in the input vector. For a non-negative input vector with the same number of dimensions as the number of channels in the on-chip intensity modulator array, by rapidly switching the operating state of each 1×1 active high-speed MZI modulator, the element x in each different input vector... i The optical power is rapidly encoded and mapped into each beam of light passing through the modulator. This completes high-throughput signal encoding, where i is the dimension of the element in the vector. The input optical signal power is the i-th 1×1 active high-speed MZI modulator.

7. An optical computing array based on a microring resonator without a free spectral range according to claim 6, characterized in that: In the array, each element of the weight vector corresponding to a 1×2 thermo-optical MZI modulator, for a weight vector with the same number of dimensions as the number of channels in the on-chip intensity modulator array, is normalized by controlling the operating state of each 1×2 thermo-optical MZI modulator, where w is the normalized element of each weight vector. i In the splitting ratio of the encoded mapped thermo-optical MZI modulator, the difference in optical power at its two output ports characterizes each real element. , Let be the splitting ratio of the i-th thermo-optical MZI modulator; for an optical signal carrying the input vector elements input to a 1×2 thermo-optical MZI modulator, it is split into two optical signals after passing through the thermo-optical MZI modulator, with optical powers of respectively and It is then passed to the next level on-chip wavelength division multiplexing beam combiner array, where i is the dimension of the element in the vector.

8. The optical computing array based on a microring resonator without a free spectral range according to claim 1, characterized in that: Both the 1×1 active high-speed MZI modulator and the 1×2 thermo-optical MZI modulator are configured as equal-arm MZI structures, and their broadband operating characteristics do not introduce additional wavelength-dependent crosstalk during input encoding and weight encoding.

9. The optical computing array according to claim 7, characterized in that, The two photodetectors in the on-chip balanced detector are respectively connected to the bus waveguide output ports of the two sets of on-chip wavelength division multiplexing beam combiner arrays, and convert the wavelength division multiplexed optical signal after beam combining in the two waveguides into photocurrent, the current values ​​of which are respectively and , The corresponding coefficients of the on-chip photodetector are represented by its final output differential current, which is the calculated result. The differential current value... ).

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