Integrated multi-channel delay compensation and coupling method and system of optical computing chip

Abstract

The invention provides an integrated multi-channel delay compensation and coupling method and system for an optical computing chip. Relative delay measurement is carried out on an input channel and a reference channel of the optical computing chip; obtaining the actual position and geometric dimension information of the port of the optical calculation chip, and combining the relative delay value of each channel and the photoresist refractive index of the photon lead to design the structure of the photon lead; cleaning the optical computing chip and the optical fiber array, fixing the optical computing chip and the optical fiber array on a transparent substrate, and dispensing photoresist to an interconnection area; performing point-by-point exposure along the interior of the photon lead design structure by using femtosecond laser to form a photon lead structure; and removing the unexposed photoresist, and dispensing a low-refractive-index matching liquid matched with the refractive index of the photoresist to form a waveguide cladding, thereby completing integrated multi-channel delay compensation and coupling of the optical computing chip. According to the invention, femtosecond laser is utilized to manufacture a photon lead structure, so that highly compact multichannel coupling interconnection with integrated delay compensation and coupling is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic chip function regulation and optical coupling, in particular to a kind of integrated multi-channel delay compensation and coupling method and system of optical computing chip realized by photonic lead. BACKGROUND

[0002] Optical neural network computing has the potential to overcome bandwidth bottleneck and achieve ultra-high computing speed. At the same time, optical neural network computing is carried out in the analog domain, effectively reducing the energy and time consumption caused by memory access. By utilizing the physical mechanism of diffraction and interference of light, high-speed and parallel optical neural network computing operations can be achieved. However, optical computing chips have high requirements for the consistency of the delay between multiple channels, and the preparation deviation of the optical computing chip and the limitations of traditional end face and grating coupling methods cannot ensure the uniformity of the delay of the multi-channel system.

[0003] In an optical computing chip, different channels carry different data, and each functional module needs the data of different channels to work normally according to a specific timing. If the delay of each channel is inconsistent, it will cause the data of different channels to arrive at the target module at different times, and then cause the incorrect operation of the functional module. To solve the problem of delay consistency of optical computing chips, the method of external delay line is often used, which has low integration density and challenges in large-scale multi-channel compensation.

[0004] Photon wire bonding technology (PWB) utilizes the nonlinear effect of femtosecond laser pulses to induce a two-photon polymerization effect in the focal point of the light beam focused in the photosensitive resin, forming a three-dimensional free-form polymer waveguide between interconnected devices, which has the potential to realize optical coupling between optical chips and efficient delay compensation within the chip. At present, the hybrid packaging of multi-channel chips of optical transceivers in optical communication systems has been realized by using photon wire bonding technology (see document: M. Blaicher et al., "Hybrid multi-chip assembly of optical communication engines by in situ 3D nano-lithography," Light Sci. Appl., vol. 9, no. 1, pp. 1-11, Dec. 2020), but the above work only uses photon wire to realize low-loss coupling of different ports, but does not realize the function of multi-channel delay compensation. By using photon wire bonding technology to process three-dimensional polymer waveguides of different physical lengths between optical computing chips and fiber arrays to compensate for the delay between multiple channels, multi-channel delay compensation coupling can be realized. However, no similar technology for photon wire compensation of multi-channel delay has been found to be described or reported, and no similar information has been collected at home and abroad. Therefore, how to meet the requirements of multi-channel delay compensation while realizing low-loss transmission of optical signals is a problem to be solved in the field. SUMMARY

[0005] The present application is directed to the above-mentioned deficiencies in the prior art, and provides an integrated multi-channel delay compensation and coupling method and system for an optical computing chip.

[0006] According to one aspect of the present application, an integrated multi-channel delay compensation and coupling method for an optical computing chip is provided, comprising:

[0007] Measuring the multi-channel relative delay values of the input channels and reference channels of the optical computing chip;

[0008] Obtaining the actual position and geometric size information of the ports of the optical computing chip, and combining the relative delay values of the channels and the photoresist refractive index of the photon wire, to design the photon wire structure and obtain the photon wire design structure;

[0009] Cleaning the optical computing chip and the fiber array and fixing them on a transparent substrate, and then using photoresist to drop and coat to the interconnection area;

[0010] Forming a photon wire structure by point-by-point exposure along the inside of the photon wire design structure;

[0011] The unexposed photoresist is removed, and a low-refractive-index matching liquid matching the refractive index of the photoresist is drop-casted to form a waveguide cladding, thereby completing the integrated multi-channel delay compensation and coupling of the photonic computing chip.

[0012] Preferably, the measurement of the multi-channel relative delay values of the input channels and the reference channel of the photonic computing chip comprises:

[0013] One end of the input channels and the reference channel of the photonic computing chip is connected to a broadband light source through an optical fiber by means of an optical alignment platform, and the other end of the input channels and the reference channel of the photonic computing chip is connected to a photodetector through an optical fiber, the optical signal is converted into an electrical signal by the photodetector, and the electrical signal is transmitted to the input channel of an oscilloscope, and the relative delay values of each channel are measured by the oscilloscope.

[0014] Preferably, the measurement of the relative delay values of each channel by the oscilloscope comprises:

[0015] The displacement of the optical fiber clamp is adjusted to obtain the best optical coupling effect.

[0016] The signal obtained on the oscilloscope is analyzed to obtain the amplitude response of each channel.

[0017] Based on the amplitude response of each channel, the phase response of each channel is calculated using the K-K relationship, and the phase information in the frequency domain is converted into the phase information in the time domain by inverse Fourier transform, and the relative delay values of each channel are obtained from the phase information in the time domain.

[0018] Preferably, the actual position and geometric dimension information of the port of the photonic computing chip are obtained, and the photonic lead structure is designed in combination with the relative delay values of each channel and the photoresist refractive index of the photonic lead, to obtain a photonic lead design structure, which comprises:

[0019] The actual position and direction angle of the port of the end-coupler and the port of the fiber array of the photonic computing chip are detected by an imaging system of a femtosecond laser platform.

[0020] According to the port size, actual coordinates, direction vector of the end-coupler and the fiber array, and the relative delay information of each channel, a segmented photonic lead structure is designed to obtain a photonic lead design structure.

[0021] Preferably, the photonic lead design structure comprises a cubic transition straight waveguide, a mode spot shape conversion waveguide, a curved waveguide, and a conical transition straight waveguide, wherein:

[0022] The cubic transition straight waveguide is a cubic waveguide structure that becomes thick from thin, the large-aperture rectangular end of the cubic transition straight waveguide completely covers the light-out end surface of the end-coupler, and the small-aperture rectangular end of the cubic transition straight waveguide is connected to the rectangular port of the mode spot shape conversion waveguide.

[0023] The mode spot shape conversion waveguide is a cylindrical waveguide structure which is transitioned from rectangle to circle, and the circular port of the mode spot shape conversion waveguide is connected to the curved waveguide;

[0024] The curved waveguide is a curved cylindrical waveguide structure with circular cross section and fixed size, and the other end of the curved waveguide is connected to the small-diameter port of the conical transition straight waveguide; the delay compensation of each channel is realized by designing the trajectory of the curved waveguide;

[0025] The conical transition straight waveguide is a tapered waveguide structure which is getting thicker, and the large-diameter port of the conical transition straight waveguide is connected to the fiber array.

[0026] Preferably, the radius of the circular cross section of the curved waveguide should meet the requirement of single-mode transmission of optical signals.

[0027] Preferably, the designing of the trajectory of the curved waveguide includes:

[0028] According to the relative delay values T1-T n , the first channel is the longest delay channel, and its relative delay value is T1, then the relative delay difference between the remaining channels and the first channel is T1-T2-T n , through the wavelength, the photoresist refractive index and the relative delay difference information, the physical length that the remaining channels need to increase relative to the first channel is calculated as L2-L n ;

[0029] Through the actual coordinates r 10 and r 11 and the unit direction vectors and of the end face coupler of the first channel and the end face of the fiber array, the values of a x0 -a z5 are adjusted by optimization method so that the loss is minimized, and finally the trajectory of the curved waveguide of the first channel is obtained The length of the curved waveguide of the first channel is wherein, and represent the first-order derivatives of x1(t), y1(t) and z1(t) with respect to the parameter t, and the following is obtained:

[0030]

[0031]

[0032]

[0033] x1(t)=ax0 t 5 +a x1 t 4 +a x2 t 3 +a x3 t 2 +a x4 t+a x5

[0034] y1(t)=a y0 t 5 +a y1 t 4 +a y2 t 3 +a y3 t 2 +a y4 t+a y5

[0035] z1(t)=a z0 t 5 +a z1 t 4 +a z2 t 3 +a z3 t 2 +a z4 t+a z5

[0036]

[0037]

[0038]

[0039]

[0040] in, represents the total loss of the curved waveguide of the first channel, α represents the material absorption and surface scattering coefficient of the curved waveguide, κ1(t) represents the inverse of the curvature radius of the curved waveguide of the first channel, t represents the parameter of the trajectory equation and 0 <t<1, represents the direction vector along the curved waveguide trajectory of the first channel, and Respectively First and second derivatives with respect to parameter t;

[0041] According to the actual coordinates of the end face couplers and fiber arrays of the remaining channels and and the unit direction vector and The lengths of the curved waveguides in the newly added remaining channels are under the constraint condition of reaches the minimum, the trajectory equation of the remaining channel is where the channel number i = 1…n.

[0042] Preferably, the optical computing chip and the optical fiber array are cleaned and fixed on a transparent optical substrate, and then a photoresist is dropped to the interconnection area, including:

[0043] The optical computing chip, the optical fiber array and the transparent optical substrate are cleaned with an organic solvent, and the optical computing chip and the optical fiber array are fixed on the transparent optical substrate;

[0044] The residual organic solvent and moisture are removed by a heating device;

[0045] The photoresist is deposited between the optical computing chip and the optical fiber array.

[0046] Preferably, the transparent optical substrate adopts a stepped glass slide or a sapphire film.

[0047] Preferably, the photonic wire structure is formed by point-by-point exposure inside the photonic wire design structure, including:

[0048] The sample coated with the photoresist is placed on a displacement table of a femtosecond laser platform;

[0049] According to the photonic wire design structure, a femtosecond laser focal point is controlled to perform point-by-point exposure on the photoresist layer.

[0050] Preferably, the femtosecond laser focal point is controlled to perform point-by-point exposure on the photoresist layer according to the photonic wire design structure, including:

[0051] The photonic wire design structure is divided into n sections along the direction of beam propagation,

[0052] The outer contour trajectory of each section is proportionally reduced to form a concentric structure with the same center point;

[0053] All contours of each concentric structure are divided into m points;

[0054] The femtosecond laser focal point is controlled to move to one of the points, and the process of turning on the femtosecond laser exposure, turning off the femtosecond laser and moving to the next point is performed, so that the femtosecond laser only exposes at the point to obtain a polymer point structure;

[0055] The above process is performed to expose the concentric structure point by point from the inside to the outside in the photoresist to obtain a polymer surface structure; the polymer surface structure is stacked to form a three-dimensional polymer body structure to obtain a photonic wire structure.

[0056] Preferably, the method further comprises:

[0057] Positioning metal marks on the optical computing chip; wherein:

[0058] The shape of the marks is rectangular or triangular;

[0059] The marks are located on the two arms of the end-coupler and are symmetric about the axis thereof;

[0060] The number of the marks depends on the length of the end-coupler.

[0061] According to another aspect of the present application, there is provided an integrated multi-channel delay compensation and coupling system for an optical computing chip, comprising:

[0062] A multi-channel delay measurement module for measuring the relative delay of the input channels and reference channels of the optical computing chip;

[0063] A photonic wire structure design module for obtaining the actual position and geometric size information of the ports of the optical computing chip, and combining the relative delay values of the channels and the photoresist refractive index of the photonic wire to design the photonic wire structure, thereby obtaining a photonic wire design structure;

[0064] A photoresist deposition module for cleaning the optical computing chip and the fiber array and fixing them on a transparent substrate, and then using photoresist to drop and coat the interconnection region;

[0065] A photonic wire exposure module for point-by-point exposure along the inside of the photonic wire design structure to form a photonic wire structure;

[0066] A photonic wire development module for removing unexposed photoresist and drop-coating a low-refractive-index matching liquid matching the photoresist refractive index to form a waveguide cladding layer, thereby completing the integrated multi-channel delay compensation and coupling function of the optical computing chip.

[0067] Preferably, the system further comprises:

[0068] A mark deposition module for depositing positioning metal marks on the optical computing chip.

[0069] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0070] The integrated multi-channel delay compensation and coupling method and system for an optical computing chip provided by the present application realize compact multi-channel delay compensation by designing the trajectory of the photonic wire, thereby saving the area overhead of the compensation part.

[0071] The application provides a method and system for integrated multi-channel delay compensation and coupling of an optical computing chip, which utilizes a two-photon polymerization effect of a femtosecond laser to manufacture a photonic lead structure, realizes highly compact, low-transmission-loss integrated multi-channel interconnection between chips for delay compensation and coupling, and supports high-accuracy optical computing operations. BRIEF DESCRIPTION OF DRAWINGS

[0072] Other features, objects and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings:

[0073] Figure 1 A work flow chart of the method for integrated multi-channel delay compensation and coupling of an optical computing chip in a preferred embodiment of the application.

[0074] Figure 2 A schematic diagram of the multi-channel delay measurement step in a preferred embodiment of the application.

[0075] Figure 3 A schematic diagram of the photonic lead segmentation structure design in a preferred embodiment of the application.

[0076] Figure 4 A schematic diagram of the photoresist deposition step in a preferred embodiment of the application.

[0077] Figure 5 A schematic diagram of the photonic lead segmented into several sections along the optical transmission direction in a preferred embodiment of the application.

[0078] Figure 6 A schematic diagram of the femtosecond laser point-by-point exposure of a single section in a preferred embodiment of the application.

[0079] Figure 7 A schematic diagram of the drop-coating of a low-refractive-index matching liquid to form a waveguide cladding in a preferred embodiment of the application.

[0080] Figure 8 A schematic diagram of the component modules of the system for integrated multi-channel delay compensation and coupling of an optical computing chip in a preferred embodiment of the application. DETAILED DESCRIPTION

[0081] The embodiments of the application are described in detail below: The embodiments are implemented on the premise of the technical solutions of the application, and detailed implementation modes and specific operation processes are given. It should be noted that, for those skilled in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are all within the protection scope of the application.

[0082] The embodiment of the present application provides a kind of integrated multi-channel delay compensation and coupling method of optical computing chip, the method utilizes femtosecond laser to manufacture three-dimensional free-form polymer waveguide between the end face coupler of optical computing chip and fiber array in situ, the transition waveguide structure is completed to the transformation of circular waveguide cross section to rectangular waveguide cross section, the multi-channel relative delay difference of optical computing chip is compensated by designing curved waveguide trajectory, and low transmission loss is realized, the scanning path of laser focus is traversed to design the photonic lead structure, and the highly compact, delay compensation and coupling integrated photonic lead structure is realized.

[0083] Specifically, as shown in Figure 1 The embodiment provides integrated multi-channel delay compensation and coupling method of optical computing chip, which can include the following operations:

[0084] S1, the multi-channel relative delay value of input channel and reference channel of optical computing chip is measured;

[0085] S2, the port actual position and geometric dimension information of optical computing chip are acquired, and the photonic lead structure is designed in combination with the relative delay value of each channel and the photoresist refractive index, to obtain photonic lead design structure;

[0086] S3, optical computing chip and fiber array are cleaned and fixed on transparent substrate, then photoresist is dropped to interconnection area;

[0087] S4, photonic lead structure is formed by point-by-point exposure along the inside of photonic lead design structure;

[0088] S5, remove unexposed photoresist, and drop low refractive index matching liquid matched with photoresist refractive index to form waveguide cladding, to complete integrated multi-channel delay compensation and coupling of optical computing chip.

[0089] The above technical solutions provided by the embodiment of the present application will be further described in detail in combination with a preferred embodiment.

[0090] S100, multi-channel delay measurement: through optical alignment platform, one end of input channel and reference channel of optical computing chip is connected to broadband light source through optical fiber, the other end is connected to photodetector through optical fiber, the optical signal is converted into electrical signal by photodetector and transmitted to the input channel of oscilloscope, and the relative delay value of each input channel is measured by oscilloscope.

[0091] In a preferred embodiment of S100, the measurement of multi-channel relative delay value further includes the following operations:

[0092] S101, place the optical computing chip on the optical substrate of the optical coupling test platform, connect one end of the to-be-tested channel and the reference channel to the wide-spectrum light source through the optical fiber, connect the other end of the to-be-tested channel and the reference channel to the photodetector through the optical fiber, convert the optical signal into an electrical signal through the photodetector, and input the electrical signal into an oscilloscope to capture and measure the received signal;

[0093] S102, by adjusting the displacement control system of the optical fiber clamp, the best optical coupling effect is realized, and by analyzing the signal obtained on the oscilloscope, the amplitude response of each channel can be obtained;

[0094] S103, based on the amplitude response of each channel, the phase response of each channel is calculated using the K-K relationship (The Kramers-Kronig relationship), and then the phase information in the frequency domain is converted into the phase information in the time domain through inverse Fourier transform, and the relative delay values T1-T n .

[0095] S200, photonic wire structure design: by using the imaging system of the femtosecond laser platform to obtain the actual position and geometric size of the port and other information, combining the relative delay value of each channel, the refractive index of the photoresist of the photonic wire, and other information to design the photonic wire structure.

[0096] In a preferred embodiment of S200, the photonic wire structure design further includes the following operations:

[0097] S201, use the imaging system of the femtosecond laser platform to detect the actual position and direction angle of the end face coupler port and the optical fiber array port of the optical computing chip;

[0098] S202, according to the port size, actual coordinates, direction vector of the end face coupler and the optical fiber array, and the relative delay value of each channel and other information, design a segmented photonic wire structure for compensating and coupling the optical fiber array and the end face coupler to ensure the consistency of loss and delay.

[0099] In S202, the imaging system can be used to directly observe to obtain the actual coordinates and direction vectors of the ports, and then design a photonic wire structure for compensating and coupling the optical fiber array and the end face coupler to ensure that the multi-channel delay is compensated while low transmission loss is achieved.

[0100] In a preferred embodiment of S202, the segmented photonic wire structure is composed of a table transition straight waveguide, a mode spot shape conversion waveguide, a curved waveguide, and a conical transition straight waveguide. Further:

[0101] The mesa-transition straight waveguide is a cubic structure that gradually thickens; the spot shape conversion waveguide is a cylindrical structure that transitions from rectangular to circular; the curved waveguide is a curved cylindrical waveguide with a circular cross-section and fixed dimensions; and the conical-transition straight waveguide is a tapered structure that gradually thickens. The large-aperture rectangular end of the mesa-transition straight waveguide completely covers the light-emitting endface of the end coupler, while the small-aperture rectangular end of the mesa-transition straight waveguide connects to the rectangular end of the spot shape conversion waveguide. The circular end of the spot shape conversion waveguide connects to the curved waveguide, while the other end of the curved waveguide connects to the small-aperture end of the conical-transition straight waveguide. Finally, the large-aperture circular end of the conical-transition straight waveguide connects to the fiber array.

[0102] In a preferred embodiment of S202, the design of the curved waveguide further includes the following operations:

[0103] First, according to the relative delay values ​​T1~T n , assuming that the first channel is the longest delayed channel and its relative delay value is T1, then the relative delay difference between the remaining channels and the first channel is T1-T2~T1-T n By using the wavelength, the refractive index of the photoresist and the relative delay difference information, it is calculated that the physical length of the remaining channel needs to be increased relative to the first channel, which is L2~L n ;

[0104] Then, the actual coordinates r of the end face of the optical fiber array and the end face coupler of the first channel are 10 and r 11 and the unit direction vector and By optimizing a x0 ~a z5 The value of to the minimum, and finally obtain the curved waveguide trajectory of the first channel Then the length of the curved waveguide of the first channel is in and Respectively represent the first-order derivatives of x1(t), y1(t) and z1(t) with respect to parameter t, where:

[0105]

[0106]

[0107]

[0108] x1(t)=a x0 t 5 +a x1 t 4 +a x2 t3 +a x3 t 2 +a x4 t+a x5

[0109] y1(t) = a y0 t 5 +a y1 t 4 +a y2 t 3 +a y3 t 2 +a y4 t+a y5

[0110] z1(t) = a z0 t 5 +a z1 t 4 +a z2 t 3 +a z3 t 2 +a z4 t+a z5

[0111]

[0112]

[0113]

[0114]

[0115] wherein, represents the total loss of the curved waveguide of the first channel, a represents the material absorption and surface scattering coefficient of the curved waveguide, κ1(t) represents the reciprocal of the curvature radius of the curved waveguide of the first channel, t represents the parameter of the trajectory equation and 0 < t < 1, represents the direction vector along the trajectory of the curved waveguide of the first channel, and respectively represent the first order derivative and the second order derivative with respect to the parameter t;

[0116] Finally, according to the actual coordinates of the end face of the end face coupler and the fiber array of the remaining channels and and the unit direction vectors and under the constraint condition that the length of the curved waveguide of the newly added remaining channel is , the same reasoning is used to make reach the minimum through the optimization method, and the trajectory equation of the remaining channel is Where the number of channels i = 1…n. In a preferred embodiment of S202, the curved waveguide has a circular cross-section, and the radius should meet the requirements of single-mode transmission of optical signals. By carefully designing the trajectory of the curved waveguide, the multi-channel delay can be compensated while achieving low transmission loss.

[0117] S300, photoresist deposition: clean and fix the optical computing chip and the fiber array on the transparent substrate, then drop the photoresist to the interconnection area, and finally place it on the heating device to complete the baking.

[0118] In a preferred embodiment of S300, photoresist deposition further includes the following operations:

[0119] S301, clean the optical computing chip, fiber array and transparent optical substrate with organic solvents such as acetone and isopropyl alcohol, and fix the optical computing chip and fiber array on the transparent optical substrate to ensure that the heights of the light output ports are basically consistent;

[0120] S302, use an oven or hot plate to remove residual organic solvents, moisture, etc.

[0121] S303, deposit photoresist between the optical computing chip and the fiber array.

[0122] In a preferred embodiment of S301, the transparent optical substrate uses glass slides, sapphire films, etc. and can be designed as a stepped shape to compensate for the height difference between the fiber array and the optical computing chip, avoid excessive alignment offset, and increase coupling loss caused by angle offset, and achieve efficient optical interconnection.

[0123] S400, photonic wire exposure: control the femtosecond laser focus to expose point by point along the designed internal structure of the photonic wire structure to form the photonic wire structure.

[0124] In a preferred embodiment of S400, photonic wire exposure further includes the following operations:

[0125] S401, place the coated sample on the displacement table of the femtosecond laser platform;

[0126] S402, according to the designed photonic wire structure, control the femtosecond laser focus to expose the photoresist layer point by point.

[0127] In a preferred embodiment of S402, the method for exposing the photoresist layer with the femtosecond laser focus point by point includes:

[0128] Divide the designed photonic wire structure into n sections along the beam propagation direction, and expose each section by controlling the femtosecond laser to form a three-dimensional polymer structure.

[0129] Further, the method of forming a three-dimensional polymer structure further comprises:

[0130] S4021, proportionally reducing the outer contour trajectory of each section to form a concentric structure with the same center point; wherein each contour trajectory shares the center with other trajectories and gradually reduces in size, for example, for a circular section, it can be divided into a concentric circle structure;

[0131] S4022, dividing all contours of each concentric structure into m points, and the point spacing depends on the size of the laser focal point;

[0132] S4023, forming a three-dimensional polymer structure by controlling the laser focal point to expose the concentric structure point by point from inside to outside in the photoresist.

[0133] In a preferred embodiment of S4023, the method of forming a three-dimensional polymer structure further comprises the following operations:

[0134] S40231, moving the laser focal point to the point - turning on the femtosecond laser exposure - turning off the femtosecond laser - moving to the next point, so that the femtosecond laser only exposes at the point to form a polymer point structure;

[0135] S40232, forming a polymer surface structure by stacking the polymer point structure inside the section;

[0136] S40233, forming a three-dimensional polymer structure by stacking the polymer surface structure.

[0137] S500, photonic lead development: removing unexposed photoresist by developing solution, and dropping low refractive index matching liquid to form waveguide cladding.

[0138] In a preferred embodiment of S500, the method of photonic lead development further comprises the following operations:

[0139] S501, removing unexposed photoresist by developing process to form a photonic lead structure;

[0140] S502, dropping low refractive index matching liquid on the photonic lead structure to form waveguide cladding. In a specific application example, the low refractive index matching liquid can use the chemical solution Cargille code3421 known in the art.

[0141] In a preferred embodiment of the present application, the above method further comprises:

[0142] S600, during the manufacturing process, a positioning metal mark is deposited on the optical computing chip. The positioning metal mark is used to position the chip structure. The shape of the mark can be rectangular or triangular, etc. The position of the mark is located on the two arms of the end face coupler and is symmetrical about its axis. The number of marks can be two or four, depending on the length of the end face coupler.

[0143] The integrated multi-channel delay compensation and coupling method for an optical computing chip provided in the above-mentioned embodiment of the present invention realizes highly compact, multi-channel inter-chip interconnection with integrated delay compensation and coupling by multi-channel delay measurement, photon lead structure design, photoresist deposition, photon lead exposure and photon lead development, and utilizing the two-photon polymerization effect of a femtosecond laser to manufacture the photon lead structure.

[0144] The technical solutions provided by the above embodiments of the present invention are described in detail below with reference to the accompanying drawings and specific application examples. It should be noted that the following description provides detailed implementation methods and structures, but the protection scope of the present invention is not limited to the following embodiments.

[0145] like Figure 1 and Figure 2 As shown in FIG, the integrated multi-channel delay compensation and coupling method of the optical computing chip implemented in this specific application example includes the following five steps:

[0146] Step 1: Multi-channel relative delay measurement: First, place the optical computing chip on the optical substrate of the optical coupling test platform, connect one end of the channel to be tested and the reference channel to a broadband light source through an optical fiber, and then connect the other end of the channel to be tested and the reference channel to a photodetector through an optical fiber. The photodetector converts the optical signal into an electrical signal, which is then transmitted to the input port of the oscilloscope to capture and measure the received signal. Next, adjust the displacement control system of the optical fiber clamp to achieve the best optical coupling effect, ensuring that the optical signal can be effectively coupled from the broadband light source into the optical computing chip and accurately detected and received by the photodetector and oscilloscope. By analyzing the signal obtained on the oscilloscope, the amplitude response of each channel can be obtained. Finally, the KK relationship (The Kramers–Kronig relationship) is used to calculate the phase response of each channel, where the KK relationship is used to obtain the phase response from the amplitude response. The phase information in the frequency domain is converted into phase information in the time domain through inverse Fourier transform, from which the relative delay values ​​T1 to T1 of each channel are obtained. n .

[0147] Step 2: Design of the photonic ribbon structure: First, the actual positions of the ports of the end-coupler 303 of the photonic chip 101 and the ports of the fiber array 301 are detected using the imaging system of the femtosecond laser platform; then, based on the information such as the port size, actual coordinates, direction vector and relative delay value of each channel of the end-coupler 303 and the fiber array 301, a segmented photonic ribbon structure is designed. The structure is composed of a platform transition straight waveguide 201, a mode spot shape conversion waveguide 202, a curved waveguide 203 and a conical transition straight waveguide 204. Among them, the platform transition straight waveguide 201 is a cube structure with a fine-to-thick transition, the mode spot shape conversion waveguide 202 is a column transition structure with a rectangular-to-circular transition, the curved waveguide 203 is a curved column waveguide with a circular cross section and a fixed size, and the conical transition straight waveguide 204 is a tapered structure with a fine-to-thick transition. The large-aperture rectangular end of the platform transition straight waveguide 201 completely covers the light-out end surface of the end-coupler 303, the small-aperture rectangular port of the platform transition straight waveguide 201 is connected to the rectangular port of the mode spot shape conversion waveguide 202, the circular port of the mode spot shape conversion waveguide 202 is connected to the curved waveguide 203, the other end of the curved waveguide 203 is connected to the small-aperture port of the conical transition straight waveguide 204, and the large-aperture circular port of the conical transition straight waveguide 204 is connected to the fiber array 301. The specific design steps of the curved waveguide 203 are as follows: first, according to the relative delay values T1-T n of each channel obtained in the multi-channel delay measurement step, it is assumed that the first channel is the longest delay channel, and its relative delay value is T1, then the relative delay difference of the remaining channels with the first channel is T1-T2-T n , through the wavelength, photonic ribbon refractive index, delay difference and other information, the physical length that needs to be added to the remaining channels relative to the first channel can be calculated as L2-L n , then the curved waveguide of the first channel is designed through the actual coordinates and direction vectors of the corresponding ports of the first channel edge-coupler 303 array and the fiber array 301, and the length of the curved waveguide is L1; finally, according to the actual coordinates and direction vectors of the remaining channels, the lengths of the curved waveguides 203 of the remaining channels are respectively L1+L2-L1+L n , as shown in FIG. 8. Figure 3

[0148] ​Step 3: Photoresist deposition: First, clean the device. Put the optical computing chip 101, the fiber array 301, and the transparent optical substrate 306 into the acetone solution and isopropyl alcohol solution for 5 minutes and 3 minutes respectively, rinse with deionized water and air dry; then, use a coarse alignment precision device to fix the optical computing chip 101 and the fiber array 301 on the transparent optical substrate 306, ensure that the heights of the light output ports are basically the same and the interconnection ports are basically aligned, and then place the sample on a heating device such as an oven or hot plate at a temperature of 100°C for 20 minutes, and then take it out and cool it to room temperature naturally; finally, use a needle tube 309 to drop photoresist 302 between the optical computing chip 101 and the fiber array 301, and use a hot plate to bake the photoresist 302 to obtain a stable photoresist 302 layer. As shown in Figure 4 .

[0149] Step 4: Photonic wire exposure: First, place the sample with photoresist on the displacement table of the femtosecond laser platform; then, according to the designed photonic wire 403 structure, use a microscope lens 501 to control the femtosecond laser focus 502 to align and expose the photoresist layer. The exposure strategy is to divide the photonic wire 403 structure into multiple cross sections along the beam propagation direction, and form a polymer surface structure at each cross section by femtosecond laser exposure. The polymer surface structures 503 are arranged in three-dimensional space in turn to form a photonic wire structure, as shown in Figure 4 . The method of processing the polymer surface structure 503 includes the following steps: each cross-sectional outer contour trajectory is scaled down proportionally to form a concentric structure with the same center point. Each contour trajectory shares the center with other trajectories, and the size gradually decreases. For example, for a circular cross section, it is divided into a concentric circle structure, and then all the contours of the concentric structure are divided into multiple points, and the point spacing depends on the size of the laser focus 502. By controlling the laser focus 502 to expose the photoresist of the concentric structure point by point from the inside to the outside, the polymer surface structure 503 is formed, and the polymer surface structure 503 is stacked to obtain a three-dimensional polymer structure. As shown in Figure 5 and Figure 6 .

[0150] Step 5: Photonic wire development: The unexposed photoresist 302 is removed by the development process to form the photonic wire 403 structure, and the photonic wire 403 structure is used to realize the interconnection between the fiber array 301 and the edge coupler 101; then, use a dropper 602 to drop a low-refractive-index matching liquid 603 on the photonic wire structure to form a waveguide cladding to isolate air. As shown in Figure 7 .

[0151] Figure 3An illustrative diagram of the structure design steps of the photonic lead 403 in the technical solution of the present application is given. The photonic lead 403 structure is divided into four parts: the first part 201 is a mesa transition straight waveguide, used to connect the end face coupler; the second part 202 is a mode spot shape conversion waveguide, which converts the circular cross section into a square cross section; the third part 203 is a single-mode transmission circular curved waveguide, used to compensate for multi-channel delay and alignment deviation; and the fourth part 204 is a conical transition straight waveguide, used to connect the fiber port. Among them, the mesa waveguide structure of the first part 201 has a large-size square cross section, which just covers the port of the end face coupler, and the axis is coincident with the end face coupler 101. The mode spot shape converter of the second part 202 converts the circular waveguide cross section into a square cross section, and the axis is coincident with the axis of the mesa transition straight waveguide of the first part 201. The start and end directions of the curved waveguide of the third part 203 are the same as the waveguide axis directions connected at both ends, and the cross section is circular and the radius meets the single-mode transmission requirement. The axis of the conical transition straight waveguide of the fourth part 204 is coincident with the fiber core axis.

[0152] Figure 4 An illustrative diagram of the photoresist deposition steps in the technical solution of the present application is given. First, use the syringe 309 to drop the photoresist on the interconnection area to form a photoresist layer 302 covering the interconnection area. Then, use a heating device to bake the photoresist layer to remove the solvent, thereby obtaining a stable photoresist layer 302. Among them, the optical computing chip 101 modulates the multi-wavelength signal received by the end face coupler 303 array through the delay line 307, the micro-ring resonator 305 and the wavelength division multiplexer 304, and completes the optical computing operation.

[0153] Figure 5 and Figure 6 An exposure strategy of the photonic lead in the technical solution of the present application is given. The photonic lead 403 structure is divided into multiple cross sections along the light transmission direction, and the number of cross sections depends on the size of the laser focus 502; then, the outer contour trajectory of each cross section is scaled down to form a concentric structure with the same center point. Each contour trajectory shares the center with other trajectories, and the size gradually decreases, for example, the outer contour of the circular cross section is circular, which is divided into a concentric circular structure, as shown in the rectangular cross section interior 405 and the circular cross section interior 406. By controlling the microscope lens 501 to expose each point inside each cross section, the size change of the laser focus 502 will cause the spacing between adjacent points to be different. After the laser focus scans all the points in the cross section from inside to outside, a dense polymer surface structure is finally formed. Stack the polymer surface structure to obtain a three-dimensional polymer body structure. Process all cross sections in turn according to the light transmission direction, and finally form a complete photonic lead 403 structure.

[0154] Figure 7A schematic diagram of the present application is given. After the photoresist development operation, the complete photonic wire 403 is left between the fiber array 301 and the edge coupler 303. The photonic wire 403 realizes highly compact, delay-compensated and coupled optical interconnection through the transition waveguide and the curved waveguide. The low refractive index matching liquid 603 is sucked by the dropper 602 and dropped on the photonic wire 403, and the waveguide cladding is formed after natural air drying, which reduces the waveguide loss and insulates the air.

[0155] An embodiment of the present application provides an integrated multi-channel delay compensation and coupling system of an optical computing chip.

[0156] Specifically, as shown in the drawings, the integrated multi-channel delay compensation and coupling system of the optical computing chip provided by the embodiment can include the following modules: Figure 8 A multi-channel delay measurement module, which is configured to measure multi-channel relative delay values of input channels and reference channels of the optical computing chip.

[0157] A photonic wire structure design module, which is configured to obtain actual position information of ports of the optical computing chip, and combine channel delay values and photoresist refractive index of the photonic wire to design the photonic wire structure, to obtain a photonic wire design structure.

[0158] A photoresist deposition module, which is configured to clean the optical computing chip and the fiber array, and fix them on a transparent substrate, and then drop photoresist to an interconnection region.

[0159] A photonic wire exposure module, which is configured to expose the photonic wire design structure point by point to form a photonic wire structure.

[0160] A photonic wire development module, which is configured to remove unexposed photoresist, and drop low refractive index matching liquid matching the photoresist refractive index to form a waveguide cladding, to complete the integrated multi-channel delay compensation and coupling function of the optical computing chip.

[0161] In a preferred embodiment of the present application, the above system further includes:

[0162] A mark deposition module, which is configured to deposit a positioning metal mark on the optical computing chip, and the positioning metal mark is used to position the chip structure.

[0163] It should be noted that the steps in the method provided by the present application can be realized by corresponding modules, devices, units, etc. in the system, and those skilled in the art can refer to the technical scheme of the method to realize the composition of the system, i.e., the embodiments in the method can be understood as preferred examples of constructing the system, which will not be described here.

[0164] It should be noted that the steps in the method provided by the present application can be realized by corresponding modules, devices, units, etc. in the system, and those skilled in the art can refer to the technical scheme of the method to realize the composition of the system, i.e., the embodiments in the method can be understood as preferred examples of constructing the system, which will not be described here.

[0165] The above-mentioned embodiments of the present invention provide an integrated multi-channel delay compensation and coupling method and system for an optical computing chip. Through an optical alignment platform, one end of the input channel and reference channel of the optical computing chip are connected to a broadband light source through optical fibers, and the other end is connected to a photodetector through optical fibers. The photodetector converts the optical signal into an electrical signal and transmits the electrical signal to the input channel of the oscilloscope. The oscilloscope then measures the delay of each input channel. The imaging system of the femtosecond laser platform is used to obtain information such as the actual position of the port, and the photon lead structure is designed based on information such as the relative delay difference of each channel and the refractive index of the photoresist. The optical computing chip and the optical fiber array are cleaned and fixed on a transparent substrate. Then, photoresist is dripped onto the interconnection area and finally placed on a heating device to complete the curing. The focus of the femtosecond laser is controlled to expose point by point along the designed photon lead structure to form the photon lead structure. The unexposed photoresist is removed with a developer, and a low-refractive-index matching liquid is dripped on to form a waveguide cladding. The method and system provided by the above embodiments of the present invention utilize the two-photon polymerization effect of a femtosecond laser to fabricate a photonic lead structure, thereby achieving highly compact multi-channel inter-chip interconnection with integrated delay compensation and coupling.

[0166] Matters not mentioned in the above embodiments of the present invention are well known in the art.

[0167] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An integrated multi-channel delay compensation and coupling method for optical computing chips, characterized in that, The method comprises the following steps: Measuring the multi-channel relative delay values of the input channels and reference channels of the optical computing chip; Obtaining the actual position and geometric size information of the ports of the optical computing chip, and combining the relative delay values of the channels and the photoresist refractive index of the photonic lead structure to design the photonic lead structure to obtain a photonic lead design structure; Cleaning the optical computing chip and the fiber array and fixing them on a transparent substrate, and then using photoresist to drop on the interconnection area; Exposing the photonic lead structure inside the photonic lead design structure point by point to form a photonic lead structure; Removing the unexposed photoresist and dropping a low refractive index matching liquid matching the refractive index of the photoresist to form a waveguide cladding layer, and completing the integrated multi-channel delay compensation and coupling of the optical computing chip.

2. The integrated multi-channel delay compensation and coupling method of photonic computing chip according to claim 1, wherein, The method for measuring the multi-channel relative delay values of the input channels and reference channels of the optical computing chip comprises the following steps: Through the optical alignment platform, one end of the input channels and reference channels of the optical computing chip is connected to a broadband light source through an optical fiber, and the other end of the input channels and reference channels of the optical computing chip is connected to a photodetector through an optical fiber, the optical signal is converted into an electrical signal by the photodetector, and the electrical signal is transmitted to the input channel of an oscilloscope, and the relative delay values of the channels are measured by the oscilloscope; Wherein: The method for measuring the relative delay values of the channels by the oscilloscope comprises the following steps: Adjusting the displacement of the optical fiber clamp to obtain the best optical coupling effect; Analyzing the signals obtained on the oscilloscope to obtain the amplitude response of each channel; Based on the amplitude response of each channel, the phase response of each channel is calculated using the K-K relationship, and the phase information in the frequency domain is converted into the phase information in the time domain through inverse Fourier transform, and the relative delay values of the channels are obtained from the phase information in the time domain.

3. The integrated multi-channel delay compensation and coupling method of the photonic computing chip according to claim 1, wherein, The method for obtaining the actual position and geometric size information of the ports of the optical computing chip, and combining the relative delay values of the channels and the photoresist refractive index of the photonic lead structure to design the photonic lead structure to obtain a photonic lead design structure comprises the following steps: Using the imaging system of the femtosecond laser platform to detect the actual position and direction angle of the port of the end-coupler and the port of the fiber array of the optical computing chip; According to the port size, actual coordinates, direction vector of the end-coupler and the fiber array, and the relative delay value information of each channel, a segmented photonic lead structure is designed to obtain a photonic lead design structure.

4. The integrated multi-channel delay compensation and coupling method of the photonic computing chip according to claim 3, wherein, The photonic lead design structure comprises a platform transition straight waveguide, a mode spot shape conversion waveguide, a curved waveguide and a conical transition straight waveguide; wherein: The platform transition straight waveguide is a cubic waveguide structure that becomes thick from thin, the large-aperture rectangular end of the platform transition straight waveguide completely covers the light-out end surface of the end-coupler, and the small-aperture rectangular end of the platform transition straight waveguide is connected to the rectangular port of the mode spot shape conversion waveguide; The mode spot shape conversion waveguide is a cylindrical waveguide structure that transitions from rectangular to circular, and the circular port of the mode spot shape conversion waveguide is connected to the curved waveguide; The curved waveguide is a curved cylindrical waveguide structure with a circular cross section and a fixed size, and the other end of the curved waveguide is connected to a small-diameter port of a conical transition straight waveguide; the trajectory of the curved waveguide is designed to realize delay compensation of each channel; The conical transition straight waveguide is a tapered waveguide structure that becomes thicker from the small-diameter port to the large-diameter port.

5. The integrated multi-channel delay compensation and coupling method of the photonic computing chip according to claim 4, wherein, Further comprising any one or any multiple of the following: The radius of the circular cross section of the curved waveguide should meet the requirements of single-mode transmission of optical signals; The design of the trajectory of the curved waveguide includes: According to the relative delay values T1-Tn of each channel n , assuming that the first channel is the longest delay channel and its relative delay value is T1, the relative delay difference between the remaining channels and the first channel is T1-T2-T1-Tn n , through the wavelength, the photoresist refractive index and the relative delay difference information, the physical length that the remaining channels need to increase relative to the first channel is calculated as L2-Ln n ; Actual coordinates r of the end face coupler and the end face of the optical fiber array through the first channel 10 and r 11 and unit direction vector and The value of a is adjusted by optimization x0 ~a z5 , so that the loss is minimized, and finally the curved waveguide track of the first channel is obtained. The length of the curved waveguide of the first channel is and respectively represent the first order derivative of x1(t), y1(t) and z1(t) with respect to the parameter t; wherein: x1(t) = a x0 t 5 +a x1 t 4 +a x2 t 3 +a x3 t 2 +a x4 t+a x5 y1(t) = a y0 t 5 +a y1 t 4 +a y2 t 3 +a y3 t 2 +a y4 t+a y5 z1(t) = a z0 t 5 +a z1 t 4 +a z2 t 3 +a z3 t 2 +a z4 t+a z5 wherein represents the total loss of the curved waveguide of the first channel, a represents the material absorption and surface scattering coefficient of the curved waveguide, K1(t) represents the inverse of the radius of curvature of the curved waveguide of the first channel, t represents a parameter of the trajectory equation and 0 < t < 1, represents the direction vector along the curved waveguide trajectory of the first channel, and respectively represent the first and second order derivatives with respect to the parameter t; According to the end surface coordinates of the end surface coupler and the optical fiber array of the remaining channel And And the unit directional vector And Under the constraint condition that the length of the curved waveguide of the newly added remaining channel is , the same reason is obtained by optimizing the trajectory equation of the remaining channel To achieve the minimum, the trajectory equation of the remaining channel is Where the channel number i = 1…n.

6. The integrated multi-channel delay compensation and coupling method of photonic computing chips of claim 1, wherein, The optical computing chip and the fiber array are cleaned and fixed on a transparent optical substrate, and then photoresist is dropped on the interconnection area; The optical computing chip, the fiber array and the transparent optical substrate are cleaned with an organic solvent, and the optical computing chip and the fiber array are fixed on the transparent optical substrate; The residual organic solvent and moisture are removed by using a heating device; The photoresist is deposited between the optical computing chip and the fiber array; The transparent optical substrate adopts a stepped glass slide or a sapphire film. The point-by-point exposure inside the photonic wire design structure to form a photonic wire structure includes:

7. The integrated multi-channel delay compensation and coupling method of photonic computing chips of claim 1, wherein, The sample coated with glue is placed on the displacement table of the femtosecond laser platform; According to the photonic wire design structure, the focal point of the femtosecond laser is controlled to perform point-by-point exposure on the photoresist layer; The point-by-point exposure of the focal point of the femtosecond laser on the photoresist layer according to the photonic wire design structure includes: The photonic wire design structure is divided into n cross sections along the direction of light beam propagation, The outer contour trajectory of each cross section is proportionally reduced to form a concentric structure with the same center point; All contours of each concentric structure are divided into m points; The focal point of the femtosecond laser is controlled to move to one of the points, and the process of turning on the femtosecond laser exposure, turning off the femtosecond laser and moving to the next point is performed, so that the femtosecond laser only exposes at this point to obtain a polymer point structure; The above process is performed to expose the concentric structure point by point from the inside to the outside in the photoresist to obtain a polymer surface structure; the polymer surface structures are stacked to form a three-dimensional polymer body structure to obtain a photonic wire structure. Further comprising: A positioning metal mark is deposited on the optical computing chip; wherein:

8. The integrated multi-channel delay compensation and coupling method of photonic computing chips according to any of claims 1-7, wherein, The shape of the mark is rectangular or triangular; The position of the mark is located on the two arms of the end-coupler and is symmetric about the axis thereof; The number of the mark is determined according to the length of the end-coupler. Comprising: A multi-channel delay measurement module for measuring the multi-channel relative delay values of the input channels and the reference channel of the optical computing chip; 9. An integrated multi-channel delay compensation and coupling system for optical computing chips, comprising: A photonic wire structure design module for obtaining the actual position and geometric size information of the ports of the optical computing chip, and combining the relative delay values of each channel and the refractive index of the photoresist of the photonic wire to design the photonic wire structure to obtain a photonic wire design structure; A photoresist deposition module for cleaning and fixing the optical computing chip and the fiber array on a transparent substrate, and then dropping photoresist on the interconnection area; ​ ​ A photonic wire exposure module for point-by-point exposure along the inside of the photonic wire design structure to form a photonic wire structure; A photonic wire development module for removing unexposed photoresist and dropping a low refractive index matching liquid matching the refractive index of the photoresist to form a waveguide cladding, completing the integrated multi-channel delay compensation and coupling of the optical computing chip.

10. The integrated multi-channel delay compensation and coupling system of the photonic computing chip of claim 9, wherein, Further comprising: A mark deposition module for depositing positioning metal marks on the optical computing chip.

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