Design method of power beam splitter and power beam splitter

Abstract

The embodiment of the application discloses a design method of a power beam splitter and the power beam splitter. The design method comprises the following steps: dividing a flat plate waveguide into a first region and a second region; determining the state of each pixel block in the first region by using a first simulation optimization algorithm, so that the TE 00 mode input by the input waveguide is converted into the TE 10 mode after being transmitted through the first region; determining the state of each pixel block in the second region by using a second simulation optimization algorithm, so that the TE 10 mode input at the interface between the first region and the second region is converted into the TM 00 mode after being transmitted through the second region, and the TM mode is split into two output waveguides according to a preset ratio. The technical scheme of the embodiment of the application designs a power beam splitter with polarization rotation and power splitting functions, which can rotate the polarization of input light, rotate the input TE mode into the TM mode at the output port, and simultaneously split the power.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated photonic devices, and in particular to a design method of a power splitter and the power splitter. BACKGROUND

[0002] In recent years, photonic integrated circuits (PICs) have been considered as one of the most promising platforms in the fields of optical communications, spectroscopy, metrology, quantum communications and computing, thanks to their low loss, high integration density and compatibility with complementary metal-oxide-semiconductor (CMOS) platforms. Due to the high refractive index difference between silicon and cladding material, the device size of photonic devices based on silicon-on-insulator (SOI) platform has been greatly reduced, and the SOI platform can provide more efficient and compact photonic devices than other integrated platforms such as LiNbO3. However, typical SOI-based waveguide devices are usually wider than they are high, so that the mode profiles of different polarizations can be distinguished. The TE and TM modes propagating in the SOI waveguide structure have large differences in transmission characteristics such as effective refractive index, mode field distribution and loss, which will cause strong polarization dependence and severely limit many applications including optical interconnects.

[0003] As one of the most basic components of high-density PICs, power splitters (PSs) are often used to control the flow of light to achieve many basic operations in PICs, such as transmitting, separating and combining optical signals. In fact, power splitters are essential devices for building many complex devices, such as optical logic gates, modulators, optical switches, etc. In recent years, a large number of research works on power splitters have been reported, mainly including power splitters based on directional couplers (DCs), Y-branches and multimode interference couplers (MMIs). Many of the currently proposed power splitters are based on single polarization, and few of them have polarization management functions. In many silicon optical modulators using Mach-Zehnder interferometers, polarizers and power splitters are necessary because the modulator can only work in one polarization condition, and the lack of polarization control will damage the performance of the device. Therefore, it is very important to implement polarization management in PICs, but the current power splitters often work in a specific polarization, which requires adding devices such as polarization splitters to the PS, which will hinder the realization of high-density large-scale PICs. SUMMARY

[0004] The embodiment of the present application provides a design method of a power splitter and the power splitter, the design method designs a power splitter with polarization rotation and power splitting functions, the power splitter can realize polarization rotation on input light, rotate the input TE mode into TM mode at the output port, and simultaneously realize power splitting.

[0005] According to an aspect of the present application, there is provided a design method of a power splitter, the power splitter comprising an input waveguide, two output waveguides and a slab waveguide arranged between the input waveguide and the output waveguides, the slab waveguide comprising a plurality of arrayed and equal-sized pixel blocks, the pixel blocks comprising a first state or a second state; the design method comprising:

[0006] dividing the slab waveguide into a first region and a second region;

[0007] determining, by using a first simulation optimization algorithm, the state of each of the pixel blocks in the first region, so that the TE 00 mode input by the input waveguide is converted into TE 10 mode after transmission through the first region;

[0008] determining, by using a second simulation optimization algorithm, the state of each of the pixel blocks in the second region, so that the TE 10 mode input at the interface between the first region and the second region is converted into TM 00 mode after transmission through the second region, and is split into the two output waveguides according to a preset ratio;

[0009] wherein the first region is arranged along a direction of the input waveguide pointing to the output waveguides, and the first region is located on a side of the second region close to the input waveguide.

[0010] Optionally, after determining, by using the second simulation optimization algorithm, the state of each of the pixel blocks in the second region, so that the TE 10 mode input at the interface between the first region and the second region is converted into TM 00 mode after transmission through the second region, and is split into the two output waveguides according to the preset ratio, the design method further comprises:

[0011] simulating, by using a finite-difference time-domain method, a process in which light waves of TE 00 mode input by the input waveguide are converted into light waves of TM 00 mode after transmission through the slab waveguide and are output by the two output waveguides;

[0012] comparing whether a difference between a ratio of output powers of the two output waveguides and the preset ratio is less than a preset range;

[0013] if not, repeating the first simulation optimization algorithm and the second simulation optimization algorithm until the difference between the ratio of the output powers of the two output waveguides and the preset ratio is less than the preset range.

[0014] Optionally, a first simulation optimization algorithm is used to determine the state of each pixel block within the first region, so that the TE input of the input waveguide... 00 The mode is converted to TE after being transmitted through the first area. 10 Patterns, including:

[0015] Set the initial state distribution of each pixel block within the first region;

[0016] Using the finite-difference time-domain method, TE was simulated. 00 The light wave of the pattern is input through the input waveguide and propagates in the first region to obtain... The output terminal TE of the first region is indicated. 10 The optical power of the mode, TE 00 Input optical power of the mode;

[0017] By changing the state of the first pixel block within the first region, the TE is simulated using the finite-difference time-domain method. 00 The process of the light wave of the pattern propagating in the first region yields the updated FOM1;

[0018] Determine if the updated FOM1 has increased in size;

[0019] If so, then maintain the current state of the first pixel block and perform the same state change and FOM1 calculation operation as the previous step on the next pixel block;

[0020] If not, the state of the first pixel block is restored to its initial state, and the same state change and FOM1 calculation operations are performed on the next pixel block as in the previous step.

[0021] Traverse all the pixel blocks and perform multiple iterations until FOM1 is greater than the first preset value.

[0022] Optionally, the first preset value is greater than or equal to 0.95 and less than or equal to 1.

[0023] Optionally, a second simulation optimization algorithm is used to determine the state of each pixel block within the second region, so that the TE input at the interface between the first region and the second region... 10 The mode is converted to TM after being transmitted through the second area. 00 The pattern is generated and the beam is split into two output waveguides according to a preset ratio, including:

[0024] Set the initial state distribution of each pixel block in the second region;

[0025] Using the finite-difference time-domain method, TE was simulated.10 TE mode of light inputted from the interface between the first region and the second region, and the process of transmitting the TE 10 mode of light in the second region, and splitting the TE 00 mode of light into two TM 10 modes of light, and obtaining an updated FOM2;

[0026] changing the state of a first pixel block in the second region, and simulating the TE 00 mode of light in the second region, and splitting the TE

[0027] determining whether the updated FOM2 is smaller;

[0028] if yes, keeping the current state of the first pixel block, and performing the same state changing and updated FOM2 calculating operations on a next pixel block as in the previous step;

[0029] if no, restoring the state of the first pixel block to an initial state, and performing the same state changing and updated FOM2 calculating operations on a next pixel block as in the previous step;

[0030] iterating through all the pixel blocks until the FOM2 is smaller than a second preset value.

[0031] Optionally, a second simulation optimization algorithm is used to determine the state of each pixel block in the second region, so that the TE 10 mode of light inputted from the interface between the first region and the second region is converted into a TM 00 mode of light after transmitting through the second region, and is split into two TM

[0032] setting an initial state distribution of each pixel block in the second region;

[0033] simulating the TE 10 mode of light inputted from the interface between the first region and the second region, and the process of transmitting the TE mode of light inputted from the interface between the first region and the second region, and the process of transmitting the TE 10 mode of light in the second region, and splitting the TE 00 mode of light into two TM

[0034] changing the state of a first pixel block in the second region, simulating the TE 10 mode light wave in the second region and splitting into two TM 00 mode light waves, obtaining an updated FOM2;

[0035] determining whether the updated FOM2 is smaller;

[0036] If yes, keeping the current state of the first pixel block, and performing the same state changing and updated FOM2 calculating operations on the next pixel block as in the previous step;

[0037] If no, restoring the state of the first pixel block to the initial state, and performing the same state changing and updated FOM2 calculating operations on the next pixel block as in the previous step;

[0038] iterating all the pixel blocks and performing multiple iterations until the FOM2 is smaller than a second preset value.

[0039] Optionally, the second preset value is greater than or equal to 0 and smaller than or equal to 0.07.

[0040] Optionally, the area of the first region is smaller than the area of the second region.

[0041] According to another aspect of the present application, there is provided a power splitter, comprising a silicon-on-insulator substrate, the silicon-on-insulator substrate comprising an input waveguide, two output waveguides and a slab waveguide arranged between the input waveguide and the output waveguides, the slab waveguide comprising a plurality of array-arranged and equally-sized pixel blocks, the pixel blocks comprising a first state or a second state, the state of the pixel blocks being determined by the design method described above.

[0042] TE 00 mode light beam input from the input waveguide, being converted into TM 00 mode light after transmission through the slab waveguide, and being split into two output waveguides according to a preset ratio.

[0043] Optionally, the silicon-on-insulator substrate comprises:

[0044] a silicon substrate;

[0045] a silicon dioxide layer and a silicon waveguide layer stacked in sequence on one side of the silicon substrate;

[0046] the first state is a non-etching state, and the second state is an etching state, and the pixel block in the second state is provided with a groove with a preset depth.

[0047] The design method of the power beam splitter provided by the embodiment of the present application, the power beam splitter comprises an input waveguide, two output waveguides and a flat waveguide arranged between the input waveguide and the output waveguide, the flat waveguide comprises a plurality of array-arranged and equal-size pixel blocks, the pixel blocks comprise a first state or a second state; the design method comprises the following steps: first, dividing the flat waveguide into a first region and a second region; then, determining the state of each pixel block in the first region by using a first simulation optimization algorithm, so that the TE 00 mode input by the input waveguide is converted into the TE 10 mode after being transmitted through the first region; and then, determining the state of each pixel block in the second region by using a second simulation optimization algorithm, so that the TE 10 mode input at the interface between the first region and the second region is converted into the TM 00 mode after being transmitted through the second region, and is split into the two output waveguides according to a preset ratio; wherein, the first region is arranged in a direction along which the input waveguide points to the output waveguide, and the first region is located on a side of the second region close to the input waveguide. The technical solution of the embodiment of the present application designs a power beam splitter with polarization rotation and power splitting functions, the power beam splitter can realize polarization rotation of input light, rotate the input TE mode into the TM mode at the output port, and simultaneously realize power splitting, and the power beam splitter has the advantages of simple preparation process, low cost and small size.

[0048] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0050] Figure 1 A flowchart of a design method of a power beam splitter provided by the embodiment of the present application;

[0051] Figure 2 A structural diagram of a power beam splitter provided by the embodiment of the present application;

[0052] Figure 3 A sectional structure diagram along the section line AA'; Figure 2

[0053] Figure 4 ​A detailed flowchart of S120 provided in an embodiment of the present invention.

[0054] Figure 5 This is a schematic diagram of the structure for simulation optimization of the first region provided in an embodiment of the present invention;

[0055] Figure 6 This is a schematic diagram of a specific process corresponding to S130 provided in an embodiment of the present invention.

[0056] Figure 7 This is a schematic diagram of the structure for simulation optimization of the second region provided in an embodiment of the present invention;

[0057] Figure 8 This is a schematic diagram of another specific process corresponding to S130 provided in an embodiment of the present invention;

[0058] Figure 9 This is a flowchart illustrating another design method for a power beam splitter provided in an embodiment of the present invention. Detailed Implementation

[0059] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0060] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0061] Figure 1 This is a flowchart illustrating a design method for a power beam splitter according to an embodiment of the present invention. This design method is used to design a power beam splitter with polarization rotation and power splitting functions, which can rotate TE mode light into TM mode and achieve beam splitting. Figure 2 This is a schematic diagram of a power beam splitter provided in an embodiment of the present invention, with reference to...Figure 2 The power splitter comprises an input waveguide 10, two output waveguides 20 (a first output waveguide 21 and a second output waveguide 22), and a slab waveguide 30 arranged between the input waveguide 10 and the output waveguide 20, the slab waveguide 30 comprising a plurality of arrayed and equal-sized pixel blocks 301, the pixel blocks 301 comprising a first state or a second state.

[0062] In this embodiment, the power splitter is a device based on silicon-on-insulator (SOI) technology, and the slab waveguide 30 is a waveguide structure based on a multimode interference coupler (MMI). Figure 3 To achieve the above purpose, Figure 2 FIG. 4 is a schematic view of a cross-sectional structure along the section line AA' shown in FIG. 3, which is referred to Figure 3 Optionally, the power splitter comprises a silicon substrate 100, a silicon dioxide layer 200 and a silicon waveguide layer 300 being sequentially stacked on one side of the silicon substrate 100; the first state is a non-etching state, that is, the silicon waveguide layer 300 corresponding to the pixel block 301a in the first state is not etched, and the second state is an etching state, and the pixel block 301b in the second state is provided with a groove 310 with a preset depth. In a specific implementation, the shape and depth of the groove 310 can be designed according to actual conditions, for example, the projection shape of the groove 310 on the silicon substrate 100 is circular, and the depth is less than the thickness of the silicon waveguide layer 300. It should be noted that the plurality of arrayed and equal-sized pixel blocks 301 in the slab waveguide 30 are only regional divisions of the slab waveguide when the power splitter is designed, and are not actually divided into multiple blocks. For example, in an embodiment, the slab waveguide 30 comprises 16×35 pixel blocks 301.

[0063] Referring to Figure 1 The design method provided in this embodiment comprises the following steps.

[0064] S110, dividing the slab waveguide into a first region and a second region.

[0065] Continuing to refer to Figure 2 The slab waveguide 30 is divided into a first region 31 and a second region 32, wherein the first region 31 is arranged along a direction a of the input waveguide 10 pointing to the output waveguide 20, and the first region 31 is located on one side of the second region 32 close to the input waveguide 10. Since the function of the slab waveguide 30 in this embodiment is to convert the light wave of the TE mode into the TM mode, it is difficult to directly realize the conversion from the TE mode to the TM mode, and therefore, in this embodiment, the first region 31 is used to realize the conversion from the input mode of the TE mode to the TE mode, and the second region is used to realize the conversion from the TE mode to the TM mode and splitting. 00 10 10 00

[0066] ​​​​In the embodiment, the first area 31 only implements the conversion function, and the second area 32 implements both the conversion and the beam splitting functions, and therefore, the area of the first area 31 is less than the area of the second area 32, which is optional, so as to facilitate the implementation of the preset functions. For example, in the embodiment, the first area 31 includes 16*15 pixel blocks 301, and the second area 32 includes 16*20 pixel blocks.

[0067] S120, determining the state of each pixel block in the first area by using a first simulation optimization algorithm, so that the TE 00 mode input by the input waveguide is converted into the TE 10 mode after being transmitted through the first area.

[0068] The first simulation optimization algorithm can be a direct-binary-search (DBS) algorithm, and the DBS is combined with a finite-difference time-domain (FDTD) simulation to implement the optimization of the device.

[0069] Figure 4 A specific flowchart of S120 provided in the embodiment is shown in FIG. 5. Figure 4 The first simulation optimization algorithm can be a direct-binary-search (DBS) algorithm, and the DBS is combined with a finite-difference time-domain (FDTD) simulation to implement the optimization of the device. 00 mode input by the input waveguide is converted into the TE 10 mode after being transmitted through the first area.

[0070] S121, setting an initial state distribution of each pixel block in the first area.

[0071] Figure 5 A structure diagram for simulating and optimizing the first area provided in the embodiment is shown in FIG. 6. Figure 5 The first area 31 includes 16*15 pixel blocks 301, wherein 0 represents etching (the second state) and 1 represents non-etching (the first state), and the initial state distribution is a 16*15 matrix composed of 0 and 1. In a specific implementation, the matrix of the initial state distribution can be all 0 or all 1, or a randomly distributed matrix, which is not limited in the embodiment.

[0072] S122, simulating the transmission of the TE 00 mode light wave input by the input waveguide in the first area by using a finite-difference time-domain method, to obtain , which represents the output TE 10 mode optical power of the first area, , which represents the input TE 00 mode optical power.

[0073] After the initial state distribution is determined, the first region is simulated by using the time domain finite difference simulation module of the Lumerical commercial simulation software to obtain the mode field distribution at the interface between the first region and the second region. Specifically, the merit value representing the output end TE 10 mode of the first region, representing the input light power of the TE 00 mode, that is, the light field mode of the interface between the first region and the second region has been converted from the TE 00 mode to the TE 10 mode. The result of the optimization is that the value of the FOM1 is as large as possible and close to 1.

[0074] S123, change the state of the first pixel block in the first region, simulate the process of the light wave of the TE 00 mode in the first region by using the time domain finite difference method to obtain the updated FOM1.

[0075] The first pixel block can be the first pixel point at the lower left corner. The state of the pixel block is changed, that is, the state is reversed. If the original state is 0, it is reversed to 1, and if the original state is 1, it is reversed to 0. Then the time domain finite difference FDTD method is used for simulation to obtain the value of the updated FOM1.

[0076] S124, judge whether the updated FOM1 is larger.

[0077] S125, if yes, keep the current state of the first pixel block, and perform the same state change and calculation of the updated FOM1 on the next pixel block as in the previous step.

[0078] S126, if no, restore the state of the first pixel block to the initial state, and perform the same state change and calculation of the updated FOM1 on the next pixel block as in the previous step.

[0079] If the updated FOM1 is larger, keep it reversed, and perform the same operation on the next pixel block, otherwise, return to the previous state, move to the next pixel block and perform the operation again.

[0080] S127, traverse all the pixel blocks and perform multiple iterations until the FOM1 is greater than a first preset value.

[0081] In this embodiment, the first region includes 16x15 pixel blocks, and one iteration is sufficient to traverse the 16x15 pixel blocks. Through multiple iterations until the value of the FOM1 meets the requirements, for example, in specific implementation, the first preset value is greater than or equal to 0.95 and less than or equal to 1.

[0082] S130, determining the state of each pixel block in the second region by using a second simulation optimization algorithm, so that the TE 10 mode input at the interface between the first region and the second region is converted into TM 00 mode after transmission through the second region, and is split into two output waveguides according to a preset ratio.

[0083] The second simulation optimization algorithm can also use DBS combined with FDTD to realize device optimization. The optical power output by the two output waveguides can each account for 50% of the total power, i.e., the power splitter can be a 3dB power splitter.

[0084] Figure 6 A specific flowchart of S130 corresponding to an embodiment of the present application is shown in FIG. 13. Figure 6 Optionally, the state of each pixel block in the second region is determined by using a second simulation optimization algorithm, so that the TE 10 mode input at the interface between the first region and the second region is converted into TM 00 mode after transmission through the second region, and is split into two output waveguides according to a preset ratio.

[0085] S1301, setting an initial state distribution of each pixel block in the second region.

[0086] Figure 7 A structure diagram of simulating and optimizing the second region according to an embodiment of the present application is shown in FIG. 14. Figure 7 The second region 32 includes 16x20 pixel blocks 301, and the initial state distribution of each pixel block can be similar to that of the first region.

[0087] S1302, simulating the light wave of TE 10 mode input at the interface between the first region and the second region by using a time-domain finite difference method, and obtaining, in the process of transmission through the second region, representing the optical power of TE 10 mode input at the interface between the first region and the second region, P2 and P3 representing the optical power of TM 00 mode output by the two output waveguides, respectively.

[0088] After the initial state distribution is determined, the second region is simulated by using a time-domain finite difference simulation module of a commercial simulation software Lumerical, an input optical power of TE 10 mode is given at the interface between the first region and the second region, and the second region realizes the functions of converting the light field mode from TE 10 to TM 00 and implementing power splitting. Specifically, TE mode inputted at the interface between the first region and the second region 10 P2 and P3 represent the optical power of TM 00 mode outputted by the two output waveguides respectively, the second region is optimized by using the DBS algorithm, so as to make the FOM2 value as small as possible, when the FOM2 value tends to 0, it can be known that and tend to 0.5, which proves that the second region realizes the conversion of the optical field mode from TE 10 to TM 00 , and the power is evenly divided into the two output waveguides. The optimization process of the second region is similar to that of the first region, and will not be described here.

[0089] S1303, changing the state of the first pixel block in the second region, simulating the process of the TE 10 mode optical wave propagating in the second region and being split into two TM 00 mode beams by using the finite difference time domain method, to obtain the updated FOM2.

[0090] S1304, judging whether the updated FOM2 is smaller.

[0091] S1305, if yes, keeping the current state of the first pixel block, and performing the same state changing and updated FOM2 calculating operation on the next pixel block as the previous step.

[0092] S1306, if no, restoring the state of the first pixel block to the initial state, and performing the same state changing and updated FOM2 calculating operation on the next pixel block as the previous step.

[0093] S1307, traversing all the pixel blocks, and performing multiple iterations until the FOM2 is smaller than a second preset value.

[0094] Since in actual application, the splitting ratio of the power splitter is not limited to equal division, but can also have other splitting ratios, such as 9:1, 8:2, 7:3, 6:4, etc., the design method provided in the embodiment can also set other splitting ratios. In another embodiment, Figure 8 for another S130 provided in the embodiment of the application, a specific flowchart is shown in FIG. 13B. Figure 8 Optionally, a second simulation optimization algorithm is used to determine the state of each pixel block in the second region, so that the TE 10 mode inputted at the interface between the first region and the second region is converted into TM 00 mode after propagating through the second region, and is split into two output waveguides according to a preset ratio, including:

[0095] S1311, setting the initial state distribution of each pixel block in the second region;

[0096] S1312, simulating the TE 10 mode light wave inputted by the interface between the first region and the second region, obtaining the TE 10 mode light power inputted by the interface between the first region and the second region, P2 and P3 respectively represent the TM 00 mode light power outputted by two output waveguides, x and y respectively represent the proportion of the output power of the two output waveguides in the total output power, x+y=1 and x, y are positive numbers;

[0097] S1313, changing the state of the first pixel block in the second region, and simulating the TE 10 mode light wave in the second region and splitting into two TM 00 mode processes, obtaining the updated FOM2;

[0098] S1314, judging whether the updated FOM2 is smaller;

[0099] S1315, if yes, keeping the current state of the first pixel block, and performing the same state changing and calculating the updated FOM2 operation on the next pixel block as the previous step;

[0100] S1316, if no, restoring the state of the first pixel block to the initial state, and performing the same state changing and calculating the updated FOM2 operation on the next pixel block as the previous step;

[0101] S1317, traversing all pixel blocks and performing multiple iterations until the FOM2 is smaller than the second preset value.

[0102] The specific simulation optimization process is similar to the above embodiment, which will not be described in detail here. In specific implementation, the size of the second preset value is not limited, and the closer the value is to 0, the closer the splitting ratio of the power splitter is to the preset ratio. Optionally, the second preset value is greater than or equal to 0 and less than or equal to 0.07.

[0103] The technical scheme of the embodiment of the application first divides the flat waveguide into the first region and the second region; then determines the state of each pixel block in the first region by using the first simulation optimization algorithm, so that the TE 00 mode inputted by the input waveguide is converted into the TE 10 mode after transmission through the first region; and then determines the state of each pixel block in the second region by using the second simulation optimization algorithm, so that the TE 10 mode inputted by the interface between the first region and the second region is converted into the TM 00The input light is polarized and split into two output waveguides according to a preset ratio, thereby designing a power beam splitter with polarization rotation and power splitting functions. This power beam splitter can achieve polarization rotation of the input light, rotate the input TE mode to TM mode at the output port, and simultaneously split the power. The power beam splitter has the advantages of simple manufacturing process, low cost and small size.

[0104] Figure 9 A flowchart illustrating another design method for a power beam splitter provided in an embodiment of the present invention is shown below. Figure 9 The design method includes:

[0105] S210. Divide the planar waveguide into a first region and a second region.

[0106] S220. Using the first simulation optimization algorithm, determine the state of each pixel block in the first region, so that the TE input to the input waveguide... 00 The mode is converted to TE after transmission through the first area. 10 model.

[0107] S230. Using the second simulation optimization algorithm, determine the state of each pixel block in the second region, so that the TE input at the interface between the first and second regions... 10 The mode is converted to TM after being transmitted through the second area. 00 The pattern is then split into two output waveguides according to a preset ratio.

[0108] S240. Using the finite-difference time-domain method, simulate TE. 00 The light wave of the mode is input through the input waveguide, transmitted through the planar waveguide, and output through the two output waveguides. 00 The process of light waves in a pattern.

[0109] S250. Compare whether the difference between the ratio of the output power of the two output waveguides and the preset ratio is less than the preset range.

[0110] S260. If not, repeat the first simulation optimization algorithm and the second simulation optimization algorithm until the difference between the ratio of the output power of the two output waveguides and the preset ratio is less than the preset range.

[0111] In this embodiment, after optimizing the first and second regions step by step, the optimized first and second regions are connected in series, with the input waveguide given mode as TE. 00 The optical power input is used to detect the TM mode at the output port. 00 The optical power determines the overall device. Where P up P down These refer to the TM mode corresponding to the upper and lower arms of the output waveguide, respectively. 00P in refers to the optical power of the TE 00 mode. The sub-region optimization is to save the optimization time, and the FOM value of the whole device is obtained by performing the FDTD simulation after the optimized regions are connected in series. If the ideal requirement is not reached, the DBS optimization can be performed on the whole device, so that the device capable of realizing the polarization rotation and the 3dB power splitting is obtained. It should be noted that if other splitting ratios are to be realized, only the FOM formula of the whole device needs to be changed to where x and y respectively correspond to the output proportions of the upper arm and the lower arm of the output waveguide, x+y=1, and x, y are positive numbers.

[0112] The design method provided by the above embodiment can design an ultra-compact power splitter with polarization rotation function. In order to facilitate representation, the above design method is performed at a wavelength of 1550nm. In order to expand the bandwidth of the device, the FOM value can be changed in the subsequent design process, such as changing FOM1 to (i.e. the average value of multiple corresponding wave bands, and the corresponding FOM2 and the whole device FOM will also be changed), where N is the number of wavelengths used in simulation. If multiple wavelengths in a range of more than 110nm are used for the above simulation, and finally all good results are obtained, the finally designed device will be an ultra-compact, wide-band and polarization-rotating power splitter.

[0113] The embodiment of the present application also provides a power splitter, which continues to refer to Figure 2 The power splitter includes a silicon-on-insulator substrate, the silicon-on-insulator substrate includes an input waveguide 10, two output waveguides 20 (a first output waveguide 21 and a second output waveguide 22) and a slab waveguide 30 arranged between the input waveguide 10 and the output waveguide 20, the slab waveguide 30 includes a plurality of array-arranged and equal-sized pixel blocks 301, the pixel block 301 includes a first state or a second state, and the state of the pixel block 301 is determined by any one of the design methods provided by the above embodiment; the light beam of the TE 00 mode input from the input waveguide 10 is converted into the TM 00 mode after being transmitted through the slab waveguide 30, and is split into two output waveguides 20 according to a preset ratio.

[0114] Referring to Figure 3 Optionally, the silicon-on-insulator substrate includes: a silicon substrate 100; a silicon dioxide layer 200 and a silicon waveguide layer 300 which are sequentially laminated on one side of the silicon substrate 100; the first state is a non-etching state, and the second state is an etching state, and a groove 310 with a preset depth is arranged in the pixel block in the second state.

[0115] In one specific embodiment of the present application, the power splitter is a 3dB power splitter with polarization rotation, which is implemented by designing a waveguide structure based on MMI on a silicon-on-insulator (SOI) platform, the entire waveguide structure is located on a 3 mu m thick SiO2 oxide substrate, the thickness of the Si waveguide is 220 nm, which is a standard SOI platform. The width of the input waveguide and the output waveguide is set to 500 nm, and the middle slab waveguide is divided into 16x35 pixel blocks. The size of the middle slab waveguide is 1.92x4.2 mu m 2 , each pixel has a size of 120 nm x 120 nm, and the radius of the etched circular hole is 45 nm, wherein the pixel block waveguide in the non-etched state has a standard thickness of 220 nm, and the etched pixel block waveguide has an etching depth of 180 nm, and the etching circular hole is filled with air. Since the etched circular hole changes the transmission state of light in the slab waveguide, the polarization rotation function can be realized.

[0116] The 3dB power splitter with polarization rotation provided by the embodiment of the present application can realize polarization rotation of the input light and simultaneously realize power division. At present, silicon photonics devices have high requirements for polarization, and most silicon optical devices require to work in a polarization state, so a polarization splitter and a polarization rotator are needed to be added in front of the conventional power splitter to realize polarization control of light, but adding related polarization control devices will limit the integration density of PICs. Therefore, the embodiment of the present application proposes a multifunctional device with polarization rotation and power division, which can realize polarization rotation of the input waveguide light field mode and simultaneously realize uniform power splitting. The area of the slab waveguide of the multifunctional device is only 1.92x4.2 mu m 2 , and the super-compact size can be subsequently integrated and multiplexed with other devices on a photonic integrated chip platform. At the same time, the device designed in the embodiment of the present application is based on an SOI platform, and the etching shape is a circular hole, and the etching area of each pixel block remains consistent, which can effectively avoid the device manufacturing error caused by the hysteresis effect in the manufacturing process; at the same time, the device designed in the embodiment of the present application can be manufactured by a single-step etching process, which is simple to operate and low in cost.

[0117] The above specific embodiments do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A design method for a power beam splitter, characterized in that, The power beam splitter includes an input waveguide, two output waveguides, and a planar waveguide disposed between the input and output waveguides. The planar waveguide includes multiple equally sized pixel blocks arranged in an array. Each pixel block has either a first state or a second state. The first state is a non-etched state, and the second state is an etched state. The pixel block in the second state has a groove of a preset depth within it. The design method includes: The planar waveguide is divided into a first region and a second region; Using a first simulation optimization algorithm, the state of each pixel block within the first region is determined, so that the TE input of the input waveguide... 00 The mode is converted to TE after being transmitted through the first area. 10 model; Using the second simulation optimization algorithm, the state of each pixel block in the second region is determined, so that the TE input at the interface between the first region and the second region is... 10 The mode is converted to TM after being transmitted through the second area. 00 The pattern is then split into two output waveguides according to a preset ratio; The first region and the second region are arranged along the direction from the input waveguide to the output waveguide, and the first region is located on the side of the second region closer to the input waveguide.

2. The design method according to claim 1, characterized in that, Using the second simulation optimization algorithm, the state of each pixel block in the second region is determined, so that the TE input at the interface between the first region and the second region is... 10 The mode is converted to TM after being transmitted through the second area. 00 After configuring the pattern and splitting the beam into the two output waveguides according to a preset ratio, it also includes: Using the finite-difference time-domain method, TE was simulated. 00 The light wave of the mode is input through the input waveguide, transmitted through the planar waveguide, and then output as TM waves through the two output waveguides. 00 The process of light waves in a pattern; Compare whether the difference between the ratio of the output power of the two output waveguides and the preset ratio is less than a preset range; If not, repeat the first simulation optimization algorithm and the second simulation optimization algorithm until the difference between the ratio of the output power of the two output waveguides and the preset ratio is less than the preset range.

3. The design method according to claim 1, characterized in that, Using a first simulation optimization algorithm, the state of each pixel block within the first region is determined, so that the TE input of the input waveguide... 00 The mode is converted to TE after being transmitted through the first area. 10 Patterns, including: Set the initial state distribution of each pixel block within the first region; Using the finite-difference time-domain method, TE was simulated. 00 The light wave of the pattern is input through the input waveguide and propagates in the first region to obtain... , The output terminal TE of the first region is indicated. 10 The optical power of the mode, TE 00 Input optical power of the mode; By changing the state of the first pixel block within the first region, the TE is simulated using the finite-difference time-domain method. 00 The process of the light wave of the pattern propagating in the first region yields the updated FOM1; Determine if the updated FOM1 has increased in size; If so, then maintain the current state of the first pixel block and perform the same state change and FOM1 calculation operation as the previous step on the next pixel block; If not, the state of the first pixel block is restored to its initial state, and the same state change and FOM1 calculation operations are performed on the next pixel block as in the previous step. Traverse all the pixel blocks and perform multiple iterations until FOM1 is greater than the first preset value.

4. The design method according to claim 3, characterized in that, The first preset value is greater than or equal to 0.95 and less than or equal to 1.

5. The design method according to claim 1, characterized in that, Using the second simulation optimization algorithm, the state of each pixel block in the second region is determined, so that the TE input at the interface between the first region and the second region is... 10 The mode is converted to TM after being transmitted through the second area. 00 The pattern is generated and the beam is split into two output waveguides according to a preset ratio, including: Set the initial state distribution of each pixel block in the second region; Using the finite-difference time-domain method, TE was simulated. 10 The light wave of the pattern is input from the interface between the first region and the second region, and during its transmission in the second region, it is obtained. , TE represents the input at the interface between the first region and the second region. 10 The optical power of the mode, P2 and P3 represent the TM outputs of the two output waveguides, respectively. 00 The optical power of the mode; By changing the state of the first pixel block within the second region, the TE is simulated using the finite-difference time-domain method. 10 The light waves of the mode propagate in the second region and are split into two TM beams. 00 The process of creating the pattern yields the updated FOM2; Determine if the updated FOM2 has become smaller; If so, then maintain the current state of the first pixel block and perform the same state change and FOM2 calculation operation as the previous step on the next pixel block; If not, the state of the first pixel block is restored to its initial state, and the same state change and FOM2 calculation operations are performed on the next pixel block as in the previous step. Traverse all the pixel blocks and perform multiple iterations until FOM2 is less than the second preset value.

6. The design method according to claim 1, characterized in that, Using the second simulation optimization algorithm, the state of each pixel block in the second region is determined, so that the TE input at the interface between the first region and the second region is... 10 The mode is converted to TM after being transmitted through the second area. 00 The pattern is generated and the beam is split into two output waveguides according to a preset ratio, including: Set the initial state distribution of each pixel block in the second region; Using the finite-difference time-domain method, TE was simulated. 10 The light wave of the pattern is input from the interface between the first region and the second region, and during its transmission in the second region, it is obtained. , TE represents the input at the interface between the first region and the second region. 10 The optical power of the mode, P2 and P3 represent the TM outputs of the two output waveguides, respectively. 00 The optical power of the mode, x and y represent the proportions of the output power of the two output waveguides to the total output power, x+y=1 and x and y are both positive numbers; By changing the state of the first pixel block within the second region, the TE is simulated using the finite-difference time-domain method. 10 The light waves of the mode propagate in the second region and are split into two TM beams. 00 The process of creating the pattern yields the updated FOM2; Determine if the updated FOM2 has become smaller; If so, then maintain the current state of the first pixel block and perform the same state change and FOM2 calculation operation as the previous step on the next pixel block; If not, the state of the first pixel block is restored to its initial state, and the same state change and FOM2 calculation operations are performed on the next pixel block as in the previous step. Traverse all the pixel blocks and perform multiple iterations until FOM2 is less than the second preset value.

7. The design method according to claim 5 or 6, characterized in that, The second preset value is greater than or equal to 0 and less than or equal to 0.

07.

8. The design method according to claim 1, characterized in that, The area of ​​the first region is smaller than the area of ​​the second region.

9. A power beam splitter, characterized in that, The invention includes a silicon-on-insulator (SiI) substrate, wherein the SiI substrate includes an input waveguide, two output waveguides, and a planar waveguide disposed between the input waveguide and the output waveguides, wherein the planar waveguide includes a plurality of pixel blocks arranged in an array and of equal size, wherein the pixel blocks include a first state or a second state, and the state of the pixel blocks is determined by the design method according to any one of claims 1 to 8. TE input from the input waveguide 00 The patterned beam is converted into a TM beam after being transmitted through the planar waveguide. 00 The mode is then split into two output waveguides according to a preset ratio.

10. The power beam splitter according to claim 9, characterized in that, The silicon-on-insulator substrate includes: silicon substrate; A silicon dioxide layer and a silicon waveguide layer are sequentially stacked on one side of the silicon substrate; The first state is a non-etched state, and the second state is an etched state. In the second state, the pixel block is provided with a groove of a preset depth.

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