Micro-ring modulator and multichannel micro-ring modulation system
By adopting a Z-type PN junction interface and a multi-doped region design in the microring modulator, the problem of balancing modulation efficiency and bandwidth is solved, a balance between efficient optical signal modulation and wide bandwidth is achieved, and the preparation process is simplified, making it suitable for high-density optical communication systems.
Patent Information
- Application Number
- CN202511054364.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2025-10-03
AI Technical Summary
Existing micro-ring modulators have difficulty in achieving a balance between modulation efficiency and bandwidth, and the manufacturing process is complex and the cost is high.
A Z-shaped PN junction interface is adopted, combined with the design of lightly doped regions, medium doped regions and heavily doped regions, to increase the cross-sectional area of the depletion region and reduce the resistance value, while simplifying the preparation process.
It achieves a balance between efficient optical signal modulation and wide optoelectronic bandwidth, reduces manufacturing costs, and is suitable for high-density optical communication systems.
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Figure CN120742577A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor technology, and in particular to a micro-ring modulator and a multi-channel micro-ring modulation system. Background Art
[0002] Silicon microring modulators (MRMs) are used to provide CMOS-compatible, scalable optical signal modulation within densely packed device layouts. Carrier-depletion-mode MRMs utilize a reverse-bias voltage to exploit the plasma dispersion effect for signal modulation. The reverse-biased PN junction alleviates the limitations of minority carrier lifetimes, resulting in faster operation.
[0003] To improve the modulation efficiency, the overlap integral between the carrier density variation and the optical mode should be optimized. MRM has demonstrated that different silicon PN junction configurations, such as vertical junction, lateral junction, and L-type junction, can achieve efficient signal modulation.
[0004] The carrier depletion mode utilizes reverse bias on the PN junction to form a depletion region. By varying the width of the depletion region, the effective refractive index of the optical signal can be modulated. A wider depletion region allows for better coupling with the optical mode field. However, this increases the junction capacitance of the device, which in turn reduces bandwidth. Therefore, existing microring modulators suffer from a balance between modulation efficiency and bandwidth. Summary of the Invention
[0005] An object of the first aspect of the present application is to provide a micro-ring modulator that can simultaneously ensure high modulation efficiency and large bandwidth.
[0006] A further purpose of this application is to simplify the process and save costs.
[0007] An object of the second aspect of the present application is to provide a multi-channel micro-ring modulation system comprising a plurality of the above-mentioned micro-ring modulators, which can achieve precise modulation and filtering at a higher wavelength density.
[0008] An embodiment of the present application provides a microring modulator, comprising a silicon waveguide structure, wherein the silicon waveguide structure comprises a stacked slab layer and a Z-ridge waveguide, wherein the Z-ridge waveguide and a region directly below the Z-ridge waveguide form an interface region, wherein the interface region comprises a PN junction interface, wherein the PN junction interface comprises a first vertical interface, a horizontal interface, and a second vertical interface connected in sequence, wherein the PN junction interface is flanked by a P region and an N region, respectively.
[0009] The P region and the N region are sequentially formed with a lightly doped region, a medium doped region and a heavily doped region with increasing doping concentrations in the width direction. The lightly doped region of the P region and the lightly doped region of the N region are butted together to form the PN junction interface at the butt joint.
[0010] Furthermore, the first vertical interface and the second vertical interface are respectively located on both sides of a center plane in a width direction of the interface area.
[0011] Furthermore, the distance between the first vertical interface and the second vertical interface and the center plane is 20%-30% of the width of the Z-ridge waveguide.
[0012] Furthermore, the concentration range of the lightly doped region of the P region and the lightly doped region of the N region is 2.8e 18 cm -3 ~3.2e 18 cm -3 The concentration range of the middle doping region of the P region and the middle doping region of the N region is 7.2e 19 cm -3 ~7.4e 19 cm -3 The concentration range of the heavily doped region of the P region and the heavily doped region of the N region is 1.8e 20 cm -3 ~2.2e 20 cm -3 .
[0013] Furthermore, the P region and the N region are formed by ion implantation.
[0014] Furthermore, the micro-ring modulator includes a plurality of silicon waveguide structures isolated in the circumferential direction, and each silicon waveguide structure has a different length.
[0015] In particular, an embodiment of the present application further provides a multi-channel micro-ring modulation system, comprising a plurality of the above-mentioned micro-ring modulators.
[0016] Furthermore, the micro-ring modulator is an Add-Drop type micro-ring modulator, the radii of each micro-ring modulator are different, and the input end and the through output end of two adjacent micro-ring modulators are connected.
[0017] According to the first aspect of the present application, the PN junction interface of the micro-ring modulator is arranged in a "Z" shape, which increases the cross-sectional area of the depletion region, thereby increasing the overlapping area of the optical mode field and the depletion region, thereby improving the modulation efficiency of the micro-ring modulator; at the same time, a lightly doped region, a medium doped region and a heavily doped region are formed in the P region and the N region in the width direction, respectively, which can reduce the resistance value of the micro-ring modulator, thereby improving its optoelectronic bandwidth and achieving a balance between modulation efficiency and bandwidth. That is, the micro-ring modulator of the present application has high modulation efficiency and wide optoelectronic bandwidth.
[0018] Furthermore, the preparation process of the silicon waveguide structure of the present application is relatively simple and easy to implement, which is conducive to reducing manufacturing costs and achieving mass production.
[0019] According to a second aspect of the present application, a multi-channel micro-ring modulation system comprising a plurality of the aforementioned micro-ring modulators is provided. The system is suitable for ultra-high-density DWDM (wavelength division multiplexing / demultiplexing) systems, exhibits high scalability, enables precise modulation and filtering at higher wavelength densities, and can handle complex signal processing requirements. This system is well-suited for future demands for higher-speed and higher-capacity optical communications. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 is a schematic cross-sectional view of a microring modulator according to an embodiment of the present invention;
[0021] Figure 2 Schematic diagram of size parameters of a micro-ring modulator according to Example 1 of the present invention;
[0022] Figure 3 PN junction depletion region simulation diagram of the micro-ring modulator of Example 1 when the reverse bias voltage is 1V and 6V;
[0023] Figure 4 The effective refractive index change-voltage curves of the micro-ring modulators of Example 1 and Comparative Example 1;
[0024] Figure 5 The unit junction capacitance-voltage curves of the micro-ring modulators of Example 1 and Comparative Example 1;
[0025] Figure 6 A schematic diagram of a formation process of a PN junction interface of a micro-ring modulator according to an embodiment of the present invention;
[0026] Figure 7 is a connection diagram of a multi-channel micro-ring modulation system according to an embodiment of the present invention;
[0027] Figure 8 This is the transmission spectrum diagram of the multi-channel micro-ring modulation system of Example 2.
[0028] Reference numerals:
[0029] 100-microring modulator, 10-substrate layer, 20-insulating layer, 30-silicon waveguide layer, 40-connecting layer, 41-electrode structure, 42-isolating material, 31-planar layer, 32-Z-ridge waveguide, 33-PN junction interface, 301-first vertical interface, 302-horizontal interface, 303-second vertical interface, 34-P region, 35-N region, 36-depletion region, 304-P lightly doped region, 305-P medium doped region, 306-P heavily doped region, 307-N lightly doped region, 308-N medium doped region, 309-N heavily doped region, 200-multi-channel microring modulation system, 101-input end, 102-through output end, 103-Drop end. DETAILED DESCRIPTION
[0030] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.
[0031] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of this application are for illustrative purposes only and do not represent the only implementation method.
[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.
[0033] In this application, unless otherwise expressly specified or limited, a first feature being “above” or “below” a second feature may mean that the first feature is directly in contact with the second feature, or that the first feature and the second feature are indirectly in contact through an intermediate medium. Furthermore, a first feature being “above,” “above,” or “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below,” “below,” or “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.
[0034] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more of the relevant listed items.
[0035] Figure 1FIG. 1 is a schematic cross-sectional view of a micro-ring modulator 100 according to an embodiment of the present invention, wherein the cross-sectional view is a cross-sectional view perpendicular to the length direction of the micro-ring modulator 100. Figure 1 As shown, generally, the micro-ring modulator 100 includes a substrate layer 10, an insulating layer 20, a silicon waveguide layer 30, and a connection layer 40 stacked in sequence, wherein the silicon waveguide layer 30 can be formed on the silicon layer of an SOI silicon wafer, and the silicon substrate layer 10 and the silicon dioxide layer of the SOI silicon wafer are used to form the above-mentioned substrate layer 10 and insulating layer 20, and the connection layer 40 includes an electrode structure 41 isolated by an isolation material 42, such as two aluminum electrodes isolated by silicon dioxide. In this embodiment, the micro-ring modulator 100 includes a silicon waveguide structure, that is, the above-mentioned silicon waveguide layer 30 includes at least one silicon waveguide structure. The silicon waveguide structure includes a stacked slab layer 31 and a Z-ridge waveguide 32, and the Z-ridge waveguide 32 and the area directly below the Z-ridge waveguide 32 form an interface region (see Figure 1 The interface region comprises a PN junction interface 33, which includes a first vertical interface 301, a horizontal interface 302, and a second vertical interface 303, connected in sequence. Flanking PN junction interface 33 are a P region 34 and an N region 35, respectively. Here, first vertical interface 301 and second vertical interface 303 are planes extending in the height direction, while horizontal interface 302 is a plane perpendicular to the height direction. P region 34 and N region 35 are sequentially formed with lightly doped, medium doped, and heavily doped regions along their widths, with increasing doping concentrations. Hereinafter, the lightly doped, medium doped, and heavily doped regions of P region 34 are referred to as P lightly doped region 304, P medium doped region 305, and P heavily doped region 306, respectively. The lightly doped, medium doped, and heavily doped regions of N region 35 are referred to as N lightly doped region 307, N medium doped region 308, and N heavily doped region 309, respectively. In this embodiment, the P lightly doped region 304 and the N lightly doped region 307 are connected to each other and a PN junction interface 33 is formed at the connection.
[0036] When using the micro-ring modulator 100 for optical signal transmission, a reverse bias voltage is applied to the PN junction of the silicon waveguide structure, that is, a voltage is applied to the two electrode structures 41 mentioned above, so that a depletion region is formed at the PN junction interface 33 between the P region 34 and the N region 35. By controlling the magnitude of the applied voltage, the width of the depletion region can be adjusted, thereby changing the refractive index of the micro-ring modulator 100 and further changing the resonant frequency, thereby achieving modulation and transmission control of the optical signal.
[0037] In the present application, the PN junction interface 33 of the micro-ring modulator 100 is arranged in a "Z" shape, which increases the cross-sectional area of the depletion region, thereby increasing the overlapping area of the optical mode field and the depletion region, thereby improving the modulation efficiency of the micro-ring modulator 100; at the same time, a lightly doped region, a medium doped region, and a heavily doped region are formed in the P region 34 and the N region 35 in the width direction, respectively, which can reduce the resistance value of the micro-ring modulator 100, thereby improving its optoelectronic bandwidth and achieving a balance between modulation efficiency and bandwidth. That is, the micro-ring modulator 100 of the present application has high modulation efficiency and wide optoelectronic bandwidth.
[0038] In one embodiment, the concentration range of the P lightly doped region 304 and the N lightly doped region 307 is 2.8e 18 cm -3 ~3.2e 18 cm -3 For example, the concentration range of the P lightly doped region 304 and the N lightly doped region 307 is 2.8e 18 cm -3 , 3.0e 18 cm -3 , 3.1e 18 cm -3 or 3.2e 18 cm -3 , or 2.8e 18 cm -3 ~3.2e 18 cm -3 Any other value in the range is not limited here; the concentration range of the P doping region 305 and the N doping region 308 is 7.2e 19 cm -3 ~7.4e 19 cm -3 For example, the concentration range of the P-doped region 305 and the N-doped region 308 is 7.2e 19 cm -3 , 7.3e 19 cm -3 or 7.4e 19 cm -3 , or 7.2e 19 cm -3 ~7.4e 19 cm -3 Any other value in is not limited here; the concentration range of the P heavily doped region 306 and the N heavily doped region 309 is 1.8e 20 cm -3 ~2.2e 20 cm -3 For example, the concentration range of the P heavily doped region 306 and the N heavily doped region 309 is 1.8e 20 cm -3 , 1.9e20 cm -3 , 2.0e 20 cm -3 , 2.1e 20 cm -3 or 2.2e 20 cm -3 , or 1.8e 20 cm -3 ~2.2e 20 cm -3 Any other value in is not restricted.
[0039] In one embodiment, the first vertical interface 301 and the second vertical interface 303 are respectively located at the center plane OO' in the width direction of the interface area (see Figure 1 ) on both sides, the center plane referred to below specifically refers to the center plane OO' in the width direction of the interface region. The ratio of the distance between the first vertical interface 301 and the second vertical interface 303 from the center plane OO' to the width of the Z-ridge waveguide 32 is any value between 20% and 30%, for example, the ratio is 20%, 22%, 25%, 28% or 30%. The ratio can also be any other value between 20% and 30%, which is not limited here. For example, if the width of the Z-ridge waveguide 32 is 380nm, the distance between the first vertical interface 301 and the center plane OO' and the distance between the second vertical interface 303 and the center plane OO' are both 100nm.
[0040] Example 1
[0041] like Figure 2 As shown, the total width W0 of the micro-ring modulator 100 of this embodiment is 10380 nm, the thickness d1 of the slab layer 31 is 90 nm, the thickness d2 of the Z-ridge waveguide 32 is 130 nm, and the width W1 is 380 nm. The first vertical interface 301 is located on the left side of the center plane OO' and the distance L1 from the center plane OO' is 100 nm. The distance L2 between the horizontal interface 302 and the top surface of the Z-ridge waveguide 32 is 70 nm. The second vertical interface 303 is located on the right side of the center plane OO' and the distance L3 from the center plane OO' is 10 0nm, the distance L4 between the left edge of the P lightly doped region 304 and the left edge of the Z-type ridge waveguide 32 is 300nm, the distance L5 between the left edge of the P medium doped region 305 and the left edge of the Z-type ridge waveguide 32 is 1000nm, the distance L6 between the right edge of the N lightly doped region 307 and the right edge of the Z-type ridge waveguide 32 is 300nm, the distance L7 between the right edge of the N medium doped region 308 and the right edge of the Z-type ridge waveguide 32 is 1000nm, and the concentrations of the P lightly doped region 304 and the N lightly doped region 307 are both 3.0e 18 cm -3 The concentrations of the P-doped region 305 and the N-doped region 308 are both 7.2e19 cm -3 The concentrations of the P heavily doped region 306 and the N heavily doped region 309 are both 2.0e 20 cm -3 .
[0042] Comparative Example 1
[0043] The only difference between Comparative Example 1 and Example 1 is that the PN junction interface 33 is a vertical interface located at the center plane OO' of the interface region, ie, a conventional lateral PN junction is formed.
[0044] Simulations were performed on the PN junction of the micro-ring modulator 100 of Example 1 with reverse bias voltages of 1V and 6V, respectively. Figure 3 As shown in (a) of FIG. 1 , the width of the depletion region 36 of the micro-ring modulator 100 of Example 1 is 5 nm when the voltage is 1 V. Figure 3 As shown in (b), the width of the depletion region 36 of the micro-ring modulator 100 of Example 1 is 45 nm when the voltage is 6 V, indicating that the width of the depletion region 36 can be significantly changed by changing the voltage, that is, the refractive index can be effectively adjusted by adjusting the voltage.
[0045] Different reverse bias voltages were applied to the PN junctions of the micro-ring modulators of Example 1 and Comparative Example 1, and the differences between the refractive index of the micro-ring modulators at different voltages and the refractive index of the micro-ring modulators when no voltage was applied (i.e. Figure 4 The effective refractive index change in Figure 4 The curve in Figure 4 It can be seen that under the same voltage, the change in the effective refractive index of Example 1 is greater than that of Comparative Example 1. As the voltage increases, the difference in the effective refractive index between Example 1 and Comparative Example 1 gradually increases, indicating that the micro-ring modulator of the present application has stronger modulation capability, higher modulation efficiency, and enhanced nonlinear response.
[0046] Different reverse bias voltages were applied to the PN junctions of the micro-ring modulators of Example 1 and Comparative Example 1, and the unit junction capacitance of the micro-ring modulators under different voltages was measured. Figure 5 The curve in Figure 5 It can be seen that at the same voltage, the unit junction capacitance of Example 1 is greater than that of Comparative Example 1, which shows that the micro-ring modulator of the present application is more likely to cause a change in the effective refractive index, and thus can improve the modulation efficiency.
[0047] Figure 6Figure 1 is a schematic diagram illustrating the formation process of the PN junction interface 33 of a microring modulator 100 according to one embodiment of the present invention. In one embodiment, the P region 34 and the N region 35 are formed by ion implantation. After depositing silicon dioxide on a silicon substrate to form an insulating layer 20, a silicon layer with the same shape as the aforementioned silicon waveguide structure is formed on the insulating layer 20. The PN junction interface 33 in this embodiment can be formed by the following steps:
[0048] Step S10: forming a first mask on the SOI silicon wafer, wherein the first mask is used to expose a first region of the silicon layer. Figure 6 The area on the left side of the dotted line in (a) is then P-type doped in the first area by boron ion implantation to form a first doped area of the P region 34. The result is as shown in FIG. Figure 6 As shown in (b);
[0049] Step S20, removing the first mask and forming a second mask on the silicon layer, the second mask is used to expose the second area of the silicon layer, that is, Figure 6 The area on the right side of the dotted line in (b) is then N-type doped in the second area by phosphorus ion implantation to form a second doped area;
[0050] Step S30, removing the second mask and forming a third mask on the silicon layer, the third mask is used to expose a third communication port in a third region of the silicon layer, the third region being a region offset a certain distance from the interface between the second region and the first region toward the first region, such as Figure 6 As shown in (c), phosphorus ion implantation is performed again to perform shallow N-type doping in the third region. By controlling the depth of ion implantation, a third doping region with a height less than that of the interface region is formed. The doping concentration of the third doping region is the same as that of the second doping region, thereby completing light doping and forming a "Z"-shaped PN junction interface 33. The result is shown in FIG. Figure 6 As shown in (d) in .
[0051] Of course, in other embodiments, the doping ions may also be other ions, as long as they can form P-type doping and N-type doping of corresponding concentrations. The above-mentioned first mask, second mask and third mask can be formed by photolithography and etching of the oxide layer.
[0052] The preparation process of the silicon waveguide structure in this application is relatively simple and easy to implement, which is conducive to reducing manufacturing costs and achieving mass production.
[0053] In a further embodiment, the micro-ring modulator 100 includes a plurality of silicon waveguide structures isolated in a circumferential direction, and each silicon waveguide structure has a different length.
[0054] The present application also provides a multi-channel micro-ring modulation system 200, comprising a plurality of the aforementioned micro-ring modulators 100. Depending on the design purpose, the micro-ring modulators 100 can be all-pass or add-drop micro-ring modulators. The types of the multiple micro-ring modulators 100 can be the same or different, and the parameters (e.g., radius) of the micro-ring modulators 100 of the same type can also differ, without limitation herein.
[0055] Example 2
[0056] The multi-channel micro-ring modulation system 200 includes six micro-ring modulators 100, each of which is an Add-Drop type micro-ring modulator. The Add-Drop type micro-ring modulator has an input terminal 101, a direct output terminal 102, and a Drop terminal 103. The radii of each micro-ring modulator 100 are 7.986 nm, 7.993 nm, 8 nm, 8.007 nm, 8.014 nm, and 8.021 nm, respectively. Each micro-ring modulator 100 includes an isolated MSB segment and an LSB segment. The length ratio of the MSB segment to the LSB segment is 2:1. The cross-sectional parameters and materials of the MSB segment and the LSB segment are the same as those in Example 1. The input terminal 101 and the direct output terminal 102 of two adjacent micro-ring modulators 100 are connected to form a Figure 7 Connections shown.
[0057] The transmitted light power of the through output terminal 102 of the last micro-ring modulator 100 of the multi-channel micro-ring modulation system 200 of Example 2 is collected, such as Figure 8 As shown in the figure, the actual collected transmitted optical power forms six distinct valleys within the O-band, corresponding to the resonant absorption points of each microring modulator 100. This makes it suitable for ultra-high-density DWDM (wavelength division multiplexing / demultiplexing) systems, with high scalability, enabling precise modulation and filtering at higher wavelength densities and addressing complex signal processing requirements. This is well-suited for future demands for higher-speed and higher-capacity optical communications.
[0058] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.
Claims
1. A micro-ring modulator, characterized in that: The silicon waveguide structure includes a stacked slab layer and a Z-ridge waveguide, wherein the Z-ridge waveguide and a region directly below the Z-ridge waveguide form an interface region, wherein the interface region has a PN junction interface, wherein the PN junction interface includes a first vertical interface, a horizontal interface, and a second vertical interface connected in sequence, and wherein two sides of the PN junction interface are respectively a P region and an N region; The P region and the N region are sequentially formed with a lightly doped region, a medium doped region and a heavily doped region with increasing doping concentrations in the width direction. The lightly doped region of the P region and the lightly doped region of the N region are butted together to form the PN junction interface at the butt joint.
2. The micro-ring modulator according to claim 1, wherein: The first vertical interface and the second vertical interface are respectively located on two sides of a center plane in a width direction of the interface area.
3. The micro-ring modulator according to claim 2, wherein: The distance between the first vertical interface and the second vertical interface and the central plane is 20%-30% of the width of the Z-ridge waveguide.
4. The micro-ring modulator according to claim 1, wherein: The concentration range of the lightly doped region of the P region and the lightly doped region of the N region is 2.8e 18 cm -3 ~3.2e 18 cm -3 The concentration range of the middle doping region of the P region and the middle doping region of the N region is 7.2e 19 cm -3 ~7.4e 19 cm -3 The concentration range of the heavily doped region of the P region and the heavily doped region of the N region is 1.8e 20 cm -3 ~2.2e 20 cm -3 .
5. The micro-ring modulator according to claim 1, wherein: The P region and the N region are formed by ion implantation.
6. The micro-ring modulator according to any one of claims 1 to 5, characterized in that: The micro-ring modulator includes a plurality of silicon waveguide structures isolated in a circumferential direction, and each silicon waveguide structure has a different length.
7. A multi-channel micro-ring modulation system, characterized in that: The device comprises a plurality of micro-ring modulators according to any one of claims 1 to 6.
8. The multi-channel micro-ring modulation system according to claim 7, characterized in that: The micro-ring modulator is an Add-Drop type micro-ring modulator, the radius of each micro-ring modulator is different, and the input end and the through output end of two adjacent micro-ring modulators are connected.