Thin film lithium niobate microring filter arrays, optical vector-matrix multipliers

Abstract

The application provides a thin-film lithium niobate micro-ring filter array and an optical vector-matrix multiplier, and comprises a thin-film lithium niobate micro-ring filter array; thin-film lithium niobate micro-ring filters with a first target row number and a first target column number, thin-film lithium niobate input waveguides with the first target row number, and thin-film lithium niobate output waveguides with the first target row number, and each thin-film lithium niobate micro-ring filter is provided with a driving module; the driving module is used for adjusting the initial resonant wavelength of the corresponding thin-film lithium niobate micro-ring filter to a target resonant wavelength. The application utilizes the electro-optic effect characteristics of thin-film lithium niobate to change the resonant wavelength of the micro-ring filter. The optical vector-matrix multiplier integrated with the thin-film lithium niobate micro-ring filter array of the application has a small power consumption, less than 20 fJ per byte.

Description

Technical Field

[0001] This invention relates to the field of integrated optics, and particularly to thin-film lithium niobate microring filter arrays and optical vector-matrix multipliers. Background Technology

[0002] An optical vector-matrix multiplier is a device that uses optical methods to perform vector-matrix multiplication calculations. Currently, optical vector-matrix multipliers can be integrated onto a chip using microring filters. The microring filter performs resonant filtering on the received multi-wavelength optical signals and outputs an optical signal corresponding to the resonant wavelength.

[0003] Currently, silicon microring filters have been used to realize on-chip integrated optical vector-matrix multipliers. Silicon microring filters mainly utilize the plasma dispersion effect of silicon, and control the refractive index of silicon by changing the carrier concentration of silicon through an external electric field, thereby changing the resonant wavelength of the silicon microring filter.

[0004] In practical applications, because the resonant wavelength variation of silicon microring filters is based on the plasma dispersion effect, the on-chip integrated optical vector-matrix multiplier based on silicon microring filters consumes a large amount of power. Summary of the Invention

[0005] To address the issue of high power consumption in on-chip integrated optical vector-matrix multipliers based on silicon microring filters, this invention provides a thin-film lithium niobate microring filter array and an optical vector-matrix multiplier.

[0006] The first aspect of the present invention provides a thin-film lithium niobate microring filter array, including a thin-film lithium niobate microring filter with a first target number of rows and a first target number of columns, a thin-film lithium niobate input waveguide with a first target number of rows, and a thin-film lithium niobate output waveguide with a first target number of rows.

[0007] Each row of thin-film lithium niobate microring filters corresponds to a thin-film lithium niobate input waveguide and a thin-film lithium niobate output waveguide. Any thin-film lithium niobate input waveguide is used to input the received multi-wavelength optical signal to all thin-film lithium niobate microring filters in the corresponding row; the multi-wavelength optical signal includes multiple wavelengths; any thin-film lithium niobate output waveguide is used to receive and output the resonant filtering results of all thin-film lithium niobate microring filters in the corresponding row;

[0008] Each of the thin-film lithium niobate microring filters in each row has a different initial resonant wavelength and can resonate with each wavelength in a multi-wavelength optical signal.

[0009] Each thin-film lithium niobate microring filter is equipped with a driving module; the driving module is used to adjust the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter to the target resonant wavelength.

[0010] Optionally, when adjusting the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter to the target resonant wavelength, the drive module performs the following:

[0011] The initial resonant wavelength of the corresponding thin-film lithium niobate microring filter is adjusted to the target resonant wavelength based on the elements of the target input matrix.

[0012] Wherein, when an element of the target input matrix is ​​1, the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter is not adjusted to the target resonant wavelength;

[0013] When the elements of the target output matrix are 0, the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter is adjusted to the target resonant wavelength.

[0014] Optionally, both the thin-film lithium niobate input waveguide and the thin-film lithium niobate output waveguide can be straight waveguides.

[0015] A second aspect of the present invention provides an optical vector-matrix multiplier, comprising any of the thin-film lithium niobate microring filter arrays disclosed in the first aspect of the present invention, and further comprising a laser source module, a beam splitter module, and a detector array;

[0016] The laser source module is used to emit supercontinuum lasers;

[0017] The beam splitting module is used to split the supercontinuum laser into multiple multi-wavelength optical signals; any multi-wavelength optical signal has the same power.

[0018] A thin-film lithium niobate microring filter array is used to resonantly filter multiple received multi-wavelength optical signals and output the resonant filtering result.

[0019] The detector array is used to receive the results of the resonant filtering.

[0020] Optionally, the preset wavelength of the supercontinuous laser emitted by the laser source module includes a first number of different wavelengths; the first number is equal to the first target column number, which is the number of columns of the thin-film lithium niobate microring filter array.

[0021] Optionally, the beam splitting module is used to split the supercontinuous laser into a second number of multi-wavelength optical signals; the second number is equal to the first target row number, which is the row number of the thin-film lithium niobate microring filter array.

[0022] Optionally, the detector array may contain a third number of detectors; the third number is equal to the second number.

[0023] Optionally, each of the detectors may have a filter at its front end.

[0024] This invention provides a thin-film lithium niobate microring filter array and an optical vector-matrix multiplier, comprising a thin-film lithium niobate microring filter array; thin-film lithium niobate microring filters with a first target number of rows and a first target number of columns; a thin-film lithium niobate input waveguide with a first target number of rows; and a thin-film lithium niobate output waveguide with a first target number of rows. Each of the thin-film lithium niobate microring filters is provided with a driving module; the driving module is used to adjust the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter to the target resonant wavelength. This invention utilizes the electro-optic effect characteristics of thin-film lithium niobate to change the resonant wavelength of the microring filter. The optical vector-matrix multiplier integrated using the thin-film lithium niobate microring filter array of this invention has low power consumption, less than 20 fJ per byte. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a thin-film lithium niobate microring filter array provided in the first embodiment of this application;

[0026] Figure 2 A partial structural schematic diagram of a thin-film lithium niobate microring filter array provided in the first embodiment of this application;

[0027] Figure 3 This is a schematic diagram of an optical vector-matrix multiplier provided in the second embodiment of this application. Detailed Implementation

[0028] To facilitate the explanation of the technical solution of this application, some concepts involved in this application will be explained first below.

[0029] The principle of vector-matrix multiplication is to perform a multiplication operation between an input vector x and an input matrix w, and obtain an output vector y. The specific calculation formula is as follows:

[0030]

[0031] To address the issue of high power consumption in on-chip integrated optical vector-matrix multipliers based on silicon microring filters in practical applications, this invention provides a thin-film lithium niobate microring filter array and an optical vector-matrix multiplier based on the thin-film lithium niobate microring filter.

[0032] The first embodiment of this application discloses a thin-film lithium niobate microring filter array, comprising N rows and M columns of thin-film lithium niobate microring filters w ij N thin-film lithium niobate input waveguides and N thin-film lithium niobate output waveguides, such as Figure 1 As shown.

[0033] Where N is the number of rows of the first target matrix, M is the number of columns of the first target matrix, i = 1, 2, ..., N, j = 1, 2, ..., M; in practical applications, N corresponds to the number of columns of the input matrix, and M corresponds to the number of rows of the input matrix.

[0034] Each row of thin-film lithium niobate microring filters w i1 ,w i2 ,……w iM Each corresponds to a thin-film lithium niobate input waveguide and a thin-film lithium niobate output waveguide. Any thin-film lithium niobate input waveguide is used to input the received multi-wavelength optical signals to all thin-film lithium niobate micro-ring filters in the corresponding row; wherein, the multi-wavelength optical signals include multiple wavelengths; any thin-film lithium niobate output waveguide is used to receive and output the resonant filtering results of all thin-film lithium niobate micro-ring filters in the corresponding row.

[0035] Furthermore, both the input waveguide and the output waveguide of any thin-film lithium niobate are straight waveguides.

[0036] Each of the thin-film lithium niobate microring filters in each row has a different initial resonant wavelength and can resonate with each wavelength in a multi-wavelength optical signal.

[0037] The preset wavelengths of the multi-wavelength optical signals are x1, x2, ... x. M The initial resonant wavelength of the thin-film lithium niobate microring filter in the i-th row is λ. i1 ,λ i2 ……λ iM The radii of the thin-film lithium niobate microring filters located in the same row are all different; the radius R of the thin-film lithium niobate microring filter in the i-th row and j-th column is... ij Based on the initial resonant wavelength λ ij Confirmed, R ij With λ ij The following relationship must be satisfied:

[0038] 2πn ij R ij =aλ ij

[0039] Where, n ij Let a be the initial refractive index of the thin-film lithium niobate microring filter in the i-th row and j-th column, where a is an integer.

[0040] Each of the aforementioned thin-film lithium niobate microring filters is equipped with a driving module; the driving module is used to set the initial resonant wavelength λ of the corresponding thin-film lithium niobate microring filter. ij Adjusted to the target resonant wavelength λ' ij .

[0041] Furthermore, such as Figure 2As shown, the driving module includes two electrodes disposed on the inner and outer sides of the thin-film lithium niobate microring filter. One electrode is grounded and is the negative electrode, while the other electrode is subjected to voltage and is the positive electrode. The initial refractive index of the thin-film lithium niobate microring filter is changed by the electric field between the two electrodes.

[0042] Utilizing the electro-optic effect of thin-film lithium niobate, an electric field is applied to the corresponding thin-film lithium niobate microring filter via a driving module, thereby changing the refractive index of the thin-film lithium niobate microring waveguide, i.e., from the initial refractive index n. ij Become the target refractive index n' ij ,n' ij The following relationship must be satisfied:

[0043]

[0044] Among them, E ij Let d be the magnitude of the electric field applied by the driving module in the i-th row and j-th column to the corresponding thin-film lithium niobate microring filter. effij For the thin-film lithium niobate microring filter in the i-th row and j-th column, under electric field E ij The effective electro-optic coefficient, n effij For the thin-film lithium niobate microring filter in the i-th row and j-th column, under electric field E ij The effective refractive index below.

[0045] The target resonant wavelength λ' of the thin-film lithium niobate microring filter in row i and column j ij According to R ij and n' ij Determine according to the following formula:

[0046] 2πn′ ij R ij =aλ′ ij

[0047] When adjusting the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter to the target resonant wavelength, the drive module performs the following:

[0048] The initial resonant wavelength λ of the corresponding thin-film lithium niobate microring filter is determined based on the elements of the target input matrix. ij Adjusted to the target resonant wavelength λ' ij ;

[0049] Specifically, when an element of the target input matrix is ​​1, no electric field is applied to the corresponding thin-film lithium niobate microring filter, i.e., the initial resonant wavelength λ of the thin-film lithium niobate microring filter is not set. ij Adjusted to the target resonant wavelength λ' ij ;

[0050] When the elements of the target output matrix are 0, an electric field is applied to the corresponding thin-film lithium niobate microring filter, that is, the initial resonant wavelength λ of the corresponding thin-film lithium niobate microring filter is... ij Adjusted to the target resonant wavelength λ' ij .

[0051] This invention utilizes the electro-optic effect of thin-film lithium niobate to modify the resonant wavelength of a micro-ring filter. Because lithium niobate exhibits excellent electro-optic effects, its electro-optic coefficient d... 33 =30.8pm / V, a single microring filter can achieve a modulation rate greater than 100GHz, while the power consumption per byte is less than 20fJ and the transmission loss is as low as 2.7dB / m. Therefore, using thin-film lithium niobate microring filters for large-scale integration to realize the operation process of optical vector-matrix multipliers has broad application prospects.

[0052] The second embodiment of this application discloses an optical vector-matrix multiplier, including the thin-film lithium niobate microring filter array disclosed in the first embodiment, and further including a laser source module, a beam splitter module, and a detector array. See [link to relevant documentation]. Figure 3 .

[0053] The laser source module is used to emit supercontinuum lasers. The preset wavelength of the supercontinuum lasers includes a first number of different wavelengths. The first number is equal to the preset number M of the thin-film lithium niobate microring filter array, that is, the preset wavelengths include M different wavelengths x1, x2, ... x M .

[0054] In practical applications, a target wavelength is selected from a preset wavelength range based on the input vector. The target wavelength range contains K wavelengths, where K ≤ M; that is, when the j-th element of the input vector is 1, the target wavelength range includes wavelength x. j When the i-th element of the input vector is 0, the target wavelength does not include wavelength x. j .

[0055] The beam splitting module is used to split each supercontinuous laser beam into a second number of multi-wavelength optical signals, the second number being equal to the preset number N of the thin-film lithium niobate micro-ring filter array; any multi-wavelength optical signal has the same power and all contain the target wavelength.

[0056] A thin-film lithium niobate microring filter array is used to resonate and filter N received multi-wavelength optical signals, and output the resonant filtering result.

[0057] The detector array contains a third number of detectors, which is equal to the second number, i.e., the detector array contains N detectors y1, y2, ... y N .

[0058] Furthermore, each detector has a filter at its front end. The filter can filter out light signals of specific wavelengths. In this embodiment, the filter is configured to filter out M wavelengths x1, x2, ... x M The optical signal. After the multi-wavelength optical signal passes through the thin-film lithium niobate microring filter through which the driven module applies an electric field, it cannot be incident on the detector.

[0059] As an example, the optical vector-matrix multiplier disclosed in this application is used to implement the operation process of 4×4 order optical vector-matrix multiplication. See the following description for details:

[0060] The supercontinuum laser emitted by the laser source module is a broadband laser containing four wavelengths: x1, x2, x3, and x4. The energy of these four wavelengths is basically the same.

[0061] The beam splitting module splits the received supercontinuum laser into four multi-wavelength optical signals of equal energy, which then enter the four thin-film lithium niobate input waveguides of the thin-film lithium niobate microring filter array. The energy of the four wavelengths remains the same. Each thin-film lithium niobate input waveguide passes through four thin-film lithium niobate microring filters. Light with wavelength x1 enters w... i1 The thin-film lithium niobate microring filter resonates and is coupled to the corresponding row of thin-film lithium niobate output waveguide for output. Wavelengths x2, x3, x4 are deduced in sequence, where i = 1, 2, 3, 4.

[0062] w ij This indicates the effect of the micro-ring filter on the corresponding wavelength x. j The operation is defined as follows: where i, j = 1, 2, 3, 4. When the driving module applies an electric field to the corresponding thin-film lithium niobate microring filter, that is, when the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter is adjusted to the target resonant wavelength, w ij =0; When the driving module applies an electric field to the corresponding thin-film lithium niobate microring filter, that is, when the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter is adjusted to the target resonant wavelength, w ij =1.

[0063] At this point, the optical signal after receiving the resonant filtering signal from the thin-film lithium niobate output waveguide propagates to the left. Therefore, the thin-film lithium niobate output waveguide needs to be rotated in one direction to output the resonant filtering result.

[0064] Detector y i Receive the resonant filtering result of the output waveguide of the thin-film lithium niobate in the j-th row.

[0065] The implementation process of the above-mentioned 4×4 order optical vector-matrix multiplier can be regarded as the following vector-matrix multiplication process:

[0066]

[0067] Furthermore, when the target wavelength of the supercontinuum laser only includes two wavelengths, x2 and x3, the corresponding input vector is (0 11 0); the first row of the thin-film lithium niobate microring filter array only allows the two wavelengths x1 and x3 to be incident on the detector y1, that is, the second and fourth driving modules in the first row adjust the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter to the target resonant wavelength, and the first column of the corresponding input matrix is ​​(w 11 w 12 w 13 w 14 )=(1 0 1 0). The optical signal received by detector y1 is y1=x1w 11 +x2w 12 +x3w 13 +x4w 14 =0×1+1×0+1×1+0×0=1. And so on, the entire vector-matrix multiplication process can be completed.

[0068] This invention provides a thin-film lithium niobate microring filter array and an optical vector-matrix multiplier, comprising a thin-film lithium niobate microring filter array; thin-film lithium niobate microring filters with a first target number of rows and a first target number of columns; a thin-film lithium niobate input waveguide with a first target number of rows; and a thin-film lithium niobate output waveguide with a first target number of rows. Each of the thin-film lithium niobate microring filters is provided with a driving module; the driving module is used to adjust the initial resonant wavelength of the corresponding thin-film lithium niobate microring filter to the target resonant wavelength. This invention utilizes the electro-optic effect characteristics of thin-film lithium niobate to change the resonant wavelength of the microring filter. The optical vector-matrix multiplier integrated using the thin-film lithium niobate microring filter array of this invention has low power consumption, less than 20 fJ per byte.

[0069] Furthermore, the modulation rate of a single silicon microring filter is generally below 60 GHz, while a single thin-film lithium niobate microring filter can achieve a modulation rate greater than 100 GHz. When performing 10×10 order vector-matrix multiplication, the floating-point computing power of the thin-film lithium niobate microring filter array disclosed in this invention is 10×10×100 GHz = 10 THz; when performing 50×50 order vector-matrix multiplication, the floating-point computing power of the thin-film lithium niobate microring filter array is 50×50×100 GHz = 250 THz. It can be seen that the computing power of the thin-film lithium niobate microring filter array increases significantly with the increase in integration scale. The power consumption per byte of thin-film lithium niobate is less than 20 fJ, the power consumption for 10 THz floating-point computing power is 0.2 W, and the power consumption for 250 THz floating-point computing power is 5 W. Compared to current CPU, GPU, and FPGA technologies, the on-chip integrated optical vector-matrix multiplier based on thin-film lithium niobate microring filter arrays offers significantly increased computing power while drastically reducing power consumption, making it a promising candidate for future applications in image processing, radar filtering, and other fields.

Claims

1. A thin film lithium niobate micro-ring filter array, characterized in that, The thin-film lithium niobate micro-ring filter array includes a first target number of rows and a first target number of columns of thin-film lithium niobate micro-ring filters, a first target number of thin-film lithium niobate input waveguides, and a first target number of thin-film lithium niobate output waveguides. Each row of thin-film lithium niobate micro-ring filters corresponds to a thin-film lithium niobate input waveguide and a thin-film lithium niobate output waveguide. Any thin-film lithium niobate input waveguide is configured to input a received multi-wavelength optical signal to all thin-film lithium niobate micro-ring filters in the corresponding row. The multi-wavelength optical signal includes multiple wavelengths. Any thin-film lithium niobate output waveguide is configured to receive and output resonance filtering results of all thin-film lithium niobate micro-ring filters in the corresponding row. The initial resonance wavelengths of all thin-film lithium niobate micro-ring filters in each row are different from each other and can resonate with the wavelengths in the multi-wavelength optical signal one by one. Each thin-film lithium niobate micro-ring filter is provided with a driving module. The driving module is configured to adjust the initial resonance wavelength of the corresponding thin-film lithium niobate micro-ring filter to a target resonance wavelength.

2. A thin-film lithium niobate microring filter array according to claim 1, wherein, The driving module is configured to perform the following when adjusting the initial resonance wavelength of the corresponding thin-film lithium niobate micro-ring filter to the target resonance wavelength: determine whether to adjust the initial resonance wavelength of the corresponding thin-film lithium niobate micro-ring filter to the target resonance wavelength according to an element of a target input matrix; when the element of the target input matrix is 1, the initial resonance wavelength of the corresponding thin-film lithium niobate micro-ring filter is not adjusted to the target resonance wavelength; when the element of the target input matrix is 0, the initial resonance wavelength of the corresponding thin-film lithium niobate micro-ring filter is adjusted to the target resonance wavelength.

3. A thin-film lithium niobate micro-ring filter array according to claim 1 or 2, wherein, Any thin-film lithium niobate input waveguide and any thin-film lithium niobate output waveguide are straight waveguides.

4. An optical vector-matrix multiplier, characterized by, The thin-film lithium niobate micro-ring filter array includes a laser source module, a beam splitting module, and a detector array. The laser source module is configured to emit supercontinuum laser. The beam splitting module is configured to split the supercontinuum laser into multiple multi-wavelength optical signals. The power of any multi-wavelength optical signal is the same. The thin-film lithium niobate micro-ring filter array is configured to perform resonance filtering on the received multiple multi-wavelength optical signals and output resonance filtering results. The detector array is configured to receive the resonance filtering results.

5. An optical vector-matrix multiplier according to claim 4, wherein, The preset wavelengths of the supercontinuum laser emitted by the laser source module include a first number of different wavelengths. The first number is equal to a first target column number, and the first target column number is the number of columns of the thin-film lithium niobate micro-ring filter array.

6. An optical vector-matrix multiplier according to claim 5, wherein, The beam splitting module is configured to split the supercontinuum laser into a second number of multi-wavelength optical signals. The second number is equal to a first target row number, and the first target row number is the number of rows of the thin-film lithium niobate micro-ring filter array.

7. An optical vector-matrix multiplier according to claim 6, wherein, The detector array includes a third number of detectors. The third number is equal to the second number.

8. An optical vector-matrix multiplier according to claim 7, wherein, The front end of each detector is provided with a filter.

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