Three-port beam splitter capable of adjusting beam splitting ratio and beam splitting ratio adjusting method thereof

Abstract

The invention provides a three-port beam splitter capable of adjusting a beam splitting ratio and a beam splitting ratio adjusting method thereof, and relates to the technical field of optical beam splitters, and the three-port beam splitter is characterized in that an input waveguide and an output waveguide are oppositely arranged, and the input waveguide is connected with the output waveguide through a multimode interference area waveguide; the output waveguide comprises a first output waveguide and a second output waveguide which are not connected with each other; the multi-mode interference area waveguide is a coupling area waveguide, the multi-mode interference area waveguide is of a regular-shaped or non-linear bending type waveguide structure containing a default area, the different proportions of the default area in the multi-mode interference area waveguide enable the beam splitting ratios of output light to be different, and the different bending conditions of the multi-mode interference area waveguide enable the beam splitting ratios of the output light to be different. Through the waveguide with the default area or the nonlinear bending type multimode interference area, the beam splitting ratio of the three-port beam splitter can be adjusted through a coupling area which is small in size, large in process tolerance and easy to process, and a flat spectrum can be output.

Description

Technical Field

[0001] The present invention relates to the technical field of optical beam splitters, and in particular to a three-port beam splitter with adjustable beam splitting ratio and a beam splitting ratio adjustment method thereof. Background Art

[0002] Photonic integrated circuits (PICs) integrate a large number of optical components with microelectronic devices for advanced photonic systems on chips. As one of the basic building blocks of PICs, optical power beam splitters have been widely used in signal monitoring, signal feedback, and power distribution. Optical beam splitters are used to separate the light field into different paths in a certain proportion. There are three types of commonly used on-chip optical beam splitters, namely Y-type beam splitters, multimode interference couplers (MMI), and directional couplers.

[0003] Directional coupler (DC) is a commonly used optical power divider that can be used to obtain any splitting ratio, but it is sensitive to wavelength, which limits its application. The performance of traditional Y-branch structure devices is greatly affected by the process.

[0004] Multimode interference beam splitter (MMI) is a classic 3dB beam splitter structure. Its basic working principle is the self-image effect, that is, multiple modes exist in the multimode waveguide and interfere with each other, so that a single image or multiple images of the input mode field can be periodically generated in the transmission direction of the waveguide. When the output waveguide is located at these self-imaging points, the beam splitting function can be realized.

[0005] However, the existing multimode interference beam splitter (MMI) is usually complex in structure, and each required splitting ratio needs to be optimized individually through many numerical simulations, and the coupling area needs to be specially processed to adjust the splitting ratio. The ideal state should be to achieve any splitting ratio programmable. Summary of the invention

[0006] In view of this, the embodiments of this specification provide a three-port beam splitter with adjustable splitting ratio and a method for adjusting the splitting ratio thereof, so as to achieve the purpose of adjusting any splitting ratio through a multi-mode interference region waveguide with a smaller size and easier processing.

[0007] The embodiments of this specification provide the following technical solutions:

[0008] In one aspect, a three-port beam splitter with adjustable beam splitting ratio is provided, comprising:

[0009] Input waveguide 1, multimode interference region waveguide 2 and output waveguide;

[0010] The input waveguide 1 is arranged opposite to the output waveguide, and the input waveguide 1 is connected to the output waveguide through the multimode interference region waveguide 2;

[0011] The output waveguide includes a first output waveguide 3 and a second output waveguide 4 which are not connected to each other;

[0012] The multimode interference region waveguide 2 is an optical coupling region waveguide, wherein the multimode interference region waveguide 2 is a waveguide structure of a regular shape including a default region 201 and / or a nonlinear bending type waveguide structure, and the proportion of the default region 201 in the multimode interference region waveguide 2 is different, resulting in different output light splitting ratios, and the bending conditions of the multimode interference region waveguide 2 are different, resulting in different output light splitting ratios.

[0013] On the other hand, a method for adjusting the splitting ratio of a three-port beam splitter with adjustable splitting ratio is provided, the method comprising:

[0014] If the multimode interference region waveguide 2 is a waveguide structure of a regular shape including a default region 201, a default region calculation model is constructed, wherein the default region calculation model includes a first correlation relationship between a proportion of the default region 201 in the multimode interference region waveguide 2 and a splitting ratio of the output light;

[0015] According to the first association relationship, the proportion of the default area 201 in the multi-mode interference region waveguide 2 is adjusted to adjust the splitting ratio of the output light; or

[0016] If the multi-mode interference region waveguide 2 is a nonlinear curved waveguide structure, a boundary curve calculation model is constructed, wherein the boundary curve calculation model includes a second correlation relationship between the curvature conditions of at least two of the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204, and the fourth nonlinear curve 205;

[0017] The curvature of at least two of the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205 is adjusted according to the second association relationship, and different splitting ratios of the output light are determined based on different curvatures of the adjusted curves.

[0018] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0019] By setting a multimode interference zone waveguide with a default area and / or a nonlinear bending type, it is achieved that different splitting ratios of the three-port beam splitter can be adjusted and a flat spectrum can be output through a coupling zone waveguide with a smaller size, a larger process tolerance and easy processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a structural diagram of a first embodiment of a three-port beam splitter including a default region of the present invention;

[0022] Figure 2 is a structural diagram of a second embodiment of a three-port beam splitter including a default region of the present invention;

[0023] Figure 3 is a structural diagram of a third embodiment of a three-port beam splitter including a default region of the present invention;

[0024] Figure 4 This is a simulation effect diagram of the first embodiment with a default ratio of 0% (the beam splitting ratio is 50:50);

[0025] Figure 5 This is a simulation effect diagram of the first embodiment with a default ratio of 25% (splitting ratio is 25:75);

[0026] Figure 6 This is a simulation effect diagram of the first embodiment with a default ratio of 50% (splitting ratio is 20:80);

[0027] Figure 7 This is a simulation effect diagram of the first embodiment with a default ratio of 75% (splitting ratio is 15:85);

[0028] Figure 8 This is the structural diagram of the traditional Y-branch three-terminal beam splitter;

[0029] Fig. 9 is a structural diagram of a three-port beam splitter surrounded by curves according to an embodiment of the present invention;

[0030] Fig.10 This is a simulation effect diagram of the multi-mode interference area obtained using the first boundary curve calculation model (the beam splitting ratio is 15:85);

[0031] Fig.11 This is a simulation effect diagram of the multi-mode interference area obtained using the first boundary curve calculation model (beam splitting ratio is 30:70);

[0032] Fig.12 This is a simulation effect diagram of the multi-mode interference area obtained using the first boundary curve calculation model (the beam splitting ratio is 50:50);

[0033] Fig.13This is a simulation effect diagram of the multi-mode interference area obtained using the second boundary curve calculation model (beam splitting ratio is 10:90);

[0034] Fig.14 This is a simulation effect diagram of the multi-mode interference area obtained using the second boundary curve calculation model (beam splitting ratio is 30:70);

[0035] Fig.15 This is a simulation effect diagram of the multi-mode interference area obtained using the second boundary curve calculation model (the beam splitting ratio is 50:50).

[0036] The reference numerals in the figure are: 1, input waveguide; 2, multimode interference zone waveguide; 201, default area; 202, first nonlinear curve; 203, second nonlinear curve; 204, third nonlinear curve; 205, fourth nonlinear curve; 206, first dividing line; 207, second dividing line; 3, first output waveguide; 4, second output waveguide. DETAILED DESCRIPTION

[0037] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0038] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] like Figure 1 , Figure 2 , Figure 3 and Fig. 9 As shown, the three-port beam splitter with adjustable splitting ratio includes: an input waveguide 1, a multimode interference region waveguide 2 and an output waveguide. The input waveguide 1 is arranged opposite to the output waveguide, and the input waveguide 1 is connected to the output waveguide through the multimode interference region waveguide 2. The output waveguide includes a first output waveguide 3 and a second output waveguide 4 that are not connected to each other.

[0040] The multimode interference region waveguide 2 is a coupling region waveguide, such as Figures 1 to 3 As shown, the multimode interference region waveguide 2 may be a waveguide structure of a regular shape including a default region 201 (i.e., a default region 201 is provided on a waveguide structure of a regular shape) and / or a waveguide structure of a nonlinear bending type. The beam splitting ratio of the output light is different if the proportion of the default region 201 in the multimode interference region waveguide 2 is different, and the beam splitting ratio of the output light is different if the bending conditions of the multimode interference region waveguide 2 are different. It is achieved that by adjusting the proportion of the default region 201 in the multimode interference region waveguide 2 to be different, different beam splitting ratios can be adjusted, or by adjusting the bending conditions of the multimode interference region waveguide 2 to be different, different beam splitting ratios of the output light can be adjusted.

[0041] When implementing it, Figures 1 to 3As shown, the default area 201 is arranged on the side of the multi-mode interference region waveguide 2 facing the input waveguide 1, and the default area 201 and the input waveguide 1 are staggered.

[0042] In specific implementation, in order to increase the process tolerance of the multimode interference zone waveguide 2 and facilitate processing and achieve a smaller size, the regular shape of the multimode interference zone waveguide 2 can be any shape that is easy to process, such as polygon, circle, ellipse, etc.

[0043] For example, Figure 1 As shown, it illustrates a three-port beam splitter in which the default area 201 is set at the lower corner of the multi-mode interference region waveguide 2 and the regular shape of the multi-mode interference region waveguide 2 is a rectangle.

[0044] like Figure 2 As shown, it illustrates a three-port beam splitter in which the default area 201 is set at the lower corner of the multi-mode interference region waveguide 2 and the regular shape of the multi-mode interference region waveguide 2 is a hexagon.

[0045] like Figure 3 As shown, it illustrates a three-port beam splitter in which the default area 201 is set at the lower corner of the multi-mode interference region waveguide 2 and the regular shape of the multi-mode interference region waveguide 2 is an ellipse.

[0046] In specific implementation, the proportion of the default area 201 in the multimode interference region waveguide 2 can be calculated by the plane area of ​​the two, or by the volume of the two. In order to improve the calculation efficiency and accuracy, and to further improve the accuracy of adjusting the splitting ratio, it is proposed to calculate the proportion according to the maximum length L of the multimode interference region waveguide 2 along the propagation direction of the optical signal and the maximum length L1 of the default area 201 along the propagation direction of the optical signal, such as Figures 1 to 3 As shown, L is the maximum length of the multimode interference region waveguide 2 along the propagation direction of the optical signal. L1 is the maximum length of the default region 201 along the propagation direction of the optical signal.

[0047] When implementing it, Figure 8 As shown, Figure 8It is a traditional Y-branch structure, which cannot adjust the fractional ratio of the output light. In order to achieve the adjustment of any splitting ratio of the output light, in addition to proposing a solution to adjust the splitting ratio of the output light by adjusting the proportion of the default area 201 in the multi-mode interference area waveguide 2, the present application also proposes a solution to adjust the splitting ratio of the output light by adjusting the bending conditions of the multi-mode interference area waveguide 2. For example, if the multi-mode interference area waveguide 2 is a nonlinear curved waveguide structure, the multi-mode interference area waveguide 2 includes a first curved waveguide, a second curved waveguide, a third curved waveguide and a fourth curved waveguide, the first curved waveguide and the third curved waveguide are relatively connected along the axis of the light propagation direction to form a first curved waveguide structure, the second curved waveguide and the fourth curved waveguide are relatively connected along the axis of the light propagation direction to form a second curved waveguide structure, the first end of the first curved waveguide structure is connected to the input waveguide 1, and the The second end of the first curved waveguide structure is connected to the first end of the second curved waveguide structure, and the second end of the second curved waveguide structure is connected to the first output waveguide 3 and the second output waveguide 4. The contour line of the first curved waveguide is a first nonlinear curve 202, the contour line of the second curved waveguide is a second nonlinear curve 203, the contour line of the third curved waveguide is a third nonlinear curve 204, and the contour line of the fourth curved waveguide is a fourth nonlinear curve 205. By adjusting the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205, and by adjusting the curvature of at least two of the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205, the curvature of the multimode interference region waveguide 2 is adjusted to achieve adjustment of an arbitrary beam splitting ratio.

[0048] like Fig. 9 As shown, the multimode interference region waveguide 2 is a nonlinear curved waveguide structure, and the contour line of the first curved waveguide is a first nonlinear curve 202 (ie Fig. 9 AB curve in FIG), the contour line of the second curved waveguide is a second nonlinear curve 203 ( Fig. 9 BC curve in FIG), the contour line of the third curved waveguide is the third nonlinear curve 204 ( Fig. 9 DE curve in FIG), the contour line of the fourth curved waveguide is the fourth nonlinear curve 205 ( Fig. 9EF curve in the figure), the connection between the first end of the first curved waveguide structure and the input waveguide 1 is the first dividing line 206, and the connection between the second end of the second curved waveguide structure and the first output waveguide 3 and the second output waveguide 4 is the second dividing line 207, that is, the first dividing line 206 is the dividing line between the multimode interference region waveguide 2 and the input waveguide 1, and the second dividing line 207 is the dividing line between the multimode interference region waveguide 2 and the output waveguide. In specific implementation, the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205 can be different nonlinear curves, or partially the same or partially different nonlinear curves, the first nonlinear curve 202 and the third nonlinear curve 204 can be symmetrical or asymmetrical, and the second nonlinear curve 203 and the fourth nonlinear curve 205 can be symmetrical or asymmetrical.

[0049] In a specific implementation, the curvature of the curve may include bending conditions (such as the number of bends), curvature (such as the curvature of each bend), length of the curve, and the like.

[0050] In a specific implementation, in order to adjust the splitting ratio of the three-port beam splitter with the above-mentioned adjustable splitting ratio, the present application also provides a method for adjusting the splitting ratio of the three-port beam splitter, which comprises the following steps:

[0051] 1. Different calculation models can be determined according to the different structures of the waveguide 2 in the multi-mode interference region.

[0052] 2. If the multimode interference zone waveguide 2 is a waveguide structure of a regular shape including a default zone 201, a default zone calculation model is constructed, wherein the default zone calculation model includes a first correlation relationship between the proportion of the default zone 201 in the multimode interference zone waveguide 2 and the splitting ratio of the output light (the splitting ratio is the power ratio between each light beam when a light beam is split into two beams); and then, according to the first correlation relationship, the proportion of the default zone 201 in the multimode interference zone waveguide 2 is adjusted to adjust the splitting ratio of the output light.

[0053] 2.1. Constructing a first relationship between the maximum length L of the multimode interference region waveguide 2 along the propagation direction of the optical signal, the maximum length L1 of the default region along the propagation direction of the optical signal and the default proportion α: α=L1 / L.

[0054] 2.2. Construct the second relationship between the default proportion α and the transmission matrix T:

[0055] Specifically, the transmission matrix of the traditional 1*2MMI 3dB power divider is

[0056] 2.3. According to the first relational expression and the second relational expression, a relational expression of the normalized output optical power P2 of the first output waveguide 3 and a relational expression of the normalized output optical power P3 of the second output waveguide 4 are constructed, and then the splitting ratio is obtained as P2:P3;

[0057] in, k1 and k2 are constants related to waveguide parameters, and the splitting ratio = P2×100:P3×100.

[0058] like Figures 4 to 7 As shown, it can be seen from the simulation data that when the default proportion α changes from 0% to 75%, the output optical power of the output waveguide (the first output waveguide 3 and the second output waveguide 4) changes (the splitting ratio of the first output waveguide 3 changes from 50% to 15%, and the splitting ratio of the second output waveguide 4 changes from 50% to 85%), thereby achieving output with any splitting ratio.

[0059] 3. If the multi-mode interference zone waveguide 2 is a nonlinear curved waveguide structure, a boundary curve calculation model is constructed, wherein the boundary curve calculation model includes a second correlation relationship between the curvatures of at least two of the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204, and the fourth nonlinear curve 205; and then, the curvatures of at least two of the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204, and the fourth nonlinear curve 205 are adjusted according to the second correlation relationship, and different splitting ratios of the output light are determined based on the different curvatures after the curves are adjusted.

[0060] 3.1. Construct a first boundary curve calculation model, in which any two of the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205 in the first boundary curve calculation model are curves with fixed bending conditions, and the other two curves are curves with adjustable bending conditions.

[0061] In one embodiment, R1, R2, R3, and R4 are respectively the S-bend characterization values ​​of any one of the four nonlinear curves (the bending characterization value can be a value representing any one of the bending conditions (such as how many bends are included), the curvature (such as the curvature of each bend), and the curve length, or it can be a value determined by combining any multiple items of the bending conditions, curvature, and curve length.

[0062] The two curves in the first boundary curve calculation model are set to have fixed bending characterization values ​​(bending characterization value R1 and bending characterization value R2 are fixed values), and bending characterization value R4 is related to bending characterization value R1, bending characterization value R2, and bending characterization value R3. By changing the value of the only variable bending characterization value R3, different beam splitting ratio outputs can be achieved.

[0063] like Figures 10 to 12 As shown, it can be known from the simulation data that after using the first boundary curve calculation model to adjust any two curves of the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205 to be curved, the beam splitting ratios of 15:85, 30:70 and 50:50 can be achieved respectively.

[0064] like Fig.10 As shown, the bending characterization value R1 is set to the radius of the S bend in the S bend line = 4.5μm, and the bending characterization value R2 is set to the radius of the S bend in the S bend line = 2.5μm. When the bending characterization value R3 is the radius of the S bend in the S bend line = 0.3μm, the bending characterization value R4 is the radius of the S bend in the S bend line = 1.65μm, at this time, the beam splitting ratio is 15:85.

[0065] like Fig.11 As shown, the bending characterization value R1 is set to the radius of the S bend in the S bend line = 4.5 μm, and the bending characterization value R2 is set to the radius of the S bend in the S bend line = 2.5 μm. When the bending characterization value R3 is the radius of the S bend in the S bend line = 2 μm, the bending characterization value R4 is the radius of the S bend in the S bend line = 1.11 μm, at this time, the beam splitting ratio is 30:70.

[0066] like Fig.12 As shown, the bending characterization value R1 is set to the radius of the S bend in the S bend line = 4.5 μm, and the bending characterization value R2 is set to the radius of the S bend in the S bend line = 2.5 μm. When the bending characterization value R3 is the radius of the S bend in the S bend line = 4.5 μm, the bending characterization value R4 is the radius of the S bend in the S bend line = 2.5 μm, at this time, the beam splitting ratio is 50:50.

[0067] 3.2. Construct a second boundary curve calculation model, wherein in the second boundary curve calculation model, the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205 are all curves whose bending conditions can be adjusted. Construct the relationship between the bending characterization value R1, the bending characterization value R2, the bending characterization value R3 and the bending characterization value R4:

[0068]

[0069] R2=A3R1;

[0070] Among them, A1, A2, A3, A4, and A5 are constants.

[0071] In the second boundary curve calculation model, the bending characterization value R1, the bending characterization value R2, and the bending characterization value R4 are related to the value of the bending characterization value R3. By changing the value of the variable bending characterization value R3, different beam splitting ratio outputs can be achieved.

[0072] like Figures 13 to 15 As shown, it can be known from the simulation data that after using the second boundary curve calculation model to adjust any curve among the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205 to a curved state, the beam splitting ratios of 10:90, 30:70 and 50:50 can be achieved respectively.

[0073] like Fig.13 As shown, when the bending characterization value R1 is the radius of the S-bend in the S-bend line = 3.94 μm, the bending characterization value R2 is the radius of the S-bend in the S-bend line = 1.97 μm, the bending characterization value R3 is the radius of the S-bend in the S-bend line = 0.2 μm, and the bending characterization value R4 is the radius of the S-bend in the S-bend line = 0.11 μm, the splitting ratio is 10:90.

[0074] like Fig.14 As shown, when the bending characterization value R1 is the radius of the S-bend in the S-bend line = 8.46 μm, the bending characterization value R2 is the radius of the S-bend in the S-bend line = 4.23 μm, the bending characterization value R3 is the radius of the S-bend in the S-bend line = 3 μm, and the bending characterization value R4 is the radius of the S-bend in the S-bend line = 1.5 μm, the splitting ratio is 30:70.

[0075] like Fig.15 As shown, when the bending characterization value R1 is the radius of the S-bend in the S-bend line = 4.5μm, the bending characterization value R2 is the radius of the S-bend in the S-bend line = 2.25μm, the bending characterization value R3 is the radius of the S-bend in the S-bend line = 4.5μm, and the bending characterization value R4 is the radius of the S-bend in the S-bend line = 2.25μm, the splitting ratio is 50:50.

[0076] 3.3. The boundary curve calculation model (such as the first boundary curve calculation model or the second boundary curve calculation model) may be selected based on the accuracy requirement of the splitting ratio of the three-port beam splitter.

[0077] In the first boundary curve calculation model, two curves are fixed curves with bending conditions, and the other two curves are adjustable curves with bending conditions. The fixed curves with bending conditions can be determined by the previous simulation results, and only the bending conditions of the two curves need to be adjusted. Therefore, the calculation complexity of the first boundary calculation model is low, and the calculation time required is short. It is suitable for application scenarios where the beam splitting ratio can be adjusted through simple calculations.

[0078] In the second boundary curve calculation model, the curvature of the four curves can be adjusted. Therefore, the calculation complexity of the second boundary curve calculation model is higher, the calculation time required is longer, and the beam splitting ratio can be adjusted more accurately. It is suitable for application scenarios that require precise adjustment of the beam splitting ratio.

[0079] Specifically, in the boundary curve calculation model, the first nonlinear curve 202, the second nonlinear curve 203, the third nonlinear curve 204 and the fourth nonlinear curve 205 can be characterized by using Euler curves, S-curves, Bezier curves, polynomial functions and other curve characterization methods.

[0080] Beneficial effects of the embodiments of the present invention:

[0081] The three-port beam splitter of the embodiment of the present invention uses the self-image of the multimode interference coupler (MMI) to reduce the loss of the device, which is conducive to the realization of large-scale photon integration. By processing the default area on the multimode interference area, the influence of the manufacturing process deviation can be reduced, the process requirements are reduced, the wavelength sensitivity is reduced, and a relatively flat output spectrum is achieved; the self-image effect of the multimode interference area of ​​the curve enclosure structure is used to achieve arbitrary fractional ratio output, and the upper and lower boundaries of the multimode interference area structure can be characterized by S-curves, Euler curves, Bessel curves or polynomial functions to achieve arbitrary curve enclosure structures. By changing the curve characterization of each curve, a programmable design for adjusting the splitting ratio is provided. Compared with the traditional Y-branch structure, the device performance deterioration caused by process deviation in process preparation can be reduced; the design method of the three-port beam splitter implemented by the present invention can enable the coupling area to achieve a flat output spectrum with a smaller size, and the process tolerance is large, and a device with an arbitrary splitting ratio can be conveniently designed.

[0082] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the scope of protection of the patent of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with each other, and with each other.

Claims

1. A three-port beam splitter with adjustable splitting ratio, characterized in that: include: An input waveguide (1), a multimode interference region waveguide (2) and an output waveguide; The input waveguide (1) is arranged opposite to the output waveguide, and the input waveguide (1) is connected to the output waveguide through the multi-mode interference region waveguide (2); The output waveguide comprises a first output waveguide (3) and a second output waveguide (4) which are not connected to each other; The multimode interference region waveguide (2) is an optical coupling region waveguide, wherein the multimode interference region waveguide (2) is a waveguide structure of a regular shape including a default region (201) and / or a waveguide structure of a nonlinear bending type, and the beam splitting ratio of the output light is different when the proportion of the default region (201) in the multimode interference region waveguide (2) is different, and the beam splitting ratio of the output light is different when the bending conditions of the multimode interference region waveguide (2) are different.

2. The three-port beam splitter with adjustable splitting ratio according to claim 1, characterized in that: The default area (201) is arranged on a side of the multi-mode interference region waveguide (2) facing the input waveguide (1), and the default area (201) and the input waveguide (1) are arranged in a staggered manner.

3. The three-port beam splitter with adjustable beam splitting ratio according to claim 1, characterized in that: The regular shape includes any one of a polygon, a circle, and an ellipse.

4. The three-port beam splitter with adjustable beam splitting ratio according to claim 1, characterized in that: If the multimode interference region waveguide (2) is a nonlinear curved waveguide structure, the multimode interference region waveguide (2) comprises a first curved waveguide, a second curved waveguide, a third curved waveguide and a fourth curved waveguide, the first curved waveguide and the third curved waveguide are relatively connected along the axis of the light propagation direction to form a first curved waveguide structure, the second curved waveguide and the fourth curved waveguide are relatively connected along the axis of the light propagation direction to form a second curved waveguide structure, the first end of the first curved waveguide structure is connected to the input waveguide (1), the second end of the first curved waveguide structure is connected to the first end of the second curved waveguide structure, and the second curved waveguide structure The second end is connected to the first output waveguide (3) and the second output waveguide (4); the contour line of the first curved waveguide is a first nonlinear curve (202); the contour line of the second curved waveguide is a second nonlinear curve (203); the contour line of the third curved waveguide is a third nonlinear curve (204); and the contour line of the fourth curved waveguide is a fourth nonlinear curve (205); and the curvature of the multimode interference region waveguide (2) is adjusted by adjusting the curvature of at least two of the first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205).

5. A method for adjusting the beam splitting ratio of a three-port beam splitter with adjustable beam splitting ratio according to any one of claims 1 to 4, characterized in that: The method comprises: If the multimode interference region waveguide (2) is a waveguide structure of a regular shape including a default region (201), a default region calculation model is constructed, wherein the default region calculation model includes a first correlation relationship between the proportion of the default region (201) in the multimode interference region waveguide (2) and the splitting ratio of the output light; According to the first association relationship, the proportion of the default area (201) in the multi-mode interference region waveguide (2) is adjusted to adjust the splitting ratio of the output light; or If the multi-mode interference region waveguide (2) is a nonlinear curved waveguide structure, a boundary curve calculation model is constructed, wherein the boundary curve calculation model includes a second correlation relationship between the curvature conditions of at least two of the first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205); The curvature of at least two of the first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205) is adjusted according to the second association relationship, and different splitting ratios of the output light are determined based on different curvatures of the adjusted curves.

6. The method for adjusting the beam splitting ratio according to claim 5, characterized in that: Constructing the default area calculation model includes: Constructing a first relationship between the maximum length L of the multimode interference region waveguide (2) along the propagation direction of the optical signal, the maximum length L1 of the default region (201) along the propagation direction of the optical signal and the proportion α: α=L1 / L; The second relationship between the proportion α and the transmission matrix T is constructed: According to the first relational expression and the second relational expression, a relational expression for the normalized output optical power P2 of the first output waveguide (3) and a relational expression for the normalized output optical power P3 of the second output waveguide (4) are constructed, and the splitting ratio is P2:P3, wherein: k1 and k2 are constants related to the waveguide parameters.

7. The method for adjusting the beam splitting ratio according to claim 5, characterized in that: Constructing the boundary curve calculation model includes: Constructing a first boundary curve calculation model, in which any two of the first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205) are curves with fixed bending conditions, and the other two are curves with adjustable bending conditions; A second boundary curve calculation model is constructed, in which the first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205) are all curves whose bending conditions can be adjusted.

8. The method for adjusting the beam splitting ratio according to claim 7, characterized in that: Constructing the first boundary curve calculation model includes: The two curves can be adjusted according to the bending condition, and the bending condition of the two curves meets the following third relationship: Among them, A1 and A2 are constants, R4 is the bending characterization value of one of the two curves with adjustable bending conditions, R3 is the bending characterization value of the other of the two curves with adjustable bending conditions, and R1 and R2 are respectively pre-set bending characterization values ​​of the two curves with fixed bending conditions.

9. The method for adjusting the beam splitting ratio according to claim 7, characterized in that: Constructing the second boundary curve calculation model includes: The curvature of any two of the first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205) conforms to the following fourth relational expression: Among them, A1 and A2 are constants, R1 is the curvature characterization value of one of the two curves, and R3 is the curvature characterization value of the other of the two curves; The curvature of any two of the first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205) conforms to the following fifth relation: R2=A3R1 Wherein, A3 is a constant, R1 is the curvature characterization value of one of the two arbitrary curves, and R2 is the curvature characterization value of the other of the two arbitrary curves; The curvature of any one of the first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205) and the curvature of the other three curves satisfy the following sixth relational expression: Among them, A4 and A5 are constants, R4 is the curvature characterization value of any curve, and R1, R2, and R3 are the curvature characterization values ​​of the other three curves respectively.

10. The method for adjusting the beam splitting ratio according to any one of claims 5 to 9, characterized in that: Also includes: The first nonlinear curve (202), the second nonlinear curve (203), the third nonlinear curve (204) and the fourth nonlinear curve (205) are characterized by using an Euler curve, an S-curve, a Bezier curve and a polynomial function.

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