Four-port beam splitter, optical module and output light beam splitting ratio adjusting method
By designing the four-port beam splitter to adopt a double-finger structure and adjusting the spacing between the coupling area waveguide and the input/output waveguide, the problem of bandwidth limitation of the symmetric directional coupler and manufacturing tolerance sensitivity is solved, and arbitrary beam splitting ratio is achieved. Flat spectral output and performance improvements.
Patent Information
- Application Number
- CN202411735667.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-02-14
AI Technical Summary
The symmetrical directional coupler used in the prior art has problems with bandwidth limitations and sensitivity to manufacturing tolerances.
A four-port beam splitter adopts a double-finger structure, including a first input waveguide, a second input waveguide, a first output waveguide, a second output waveguide and a coupling waveguide. The coupling waveguide is arranged as an input coupling region waveguide and a transition region The waveguide and the output coupling region waveguide and adjust the output beam splitting ratio by adjusting the distance between the coupling region waveguide and the input/output waveguide.
The flat spectral output of arbitrary beam splitting ratios is realized under the input of both ports, which improves the performance of optical devices, reduces the impact of manufacturing process deviations on device performance, and reduces the dependence on machining accuracy.
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Figure CN119439372A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of optical communication technology, and in particular to a four-port beam splitter, an optical module, and a method for adjusting an output light splitting ratio. Background Art
[0002] In photonic integrated circuits (PICs), power dividers are key devices for optical power distribution and control, and are widely used in core modules such as wavelength multiplexers / demultiplexers, modulators, and polarization beam splitters. Existing power divider structures have their own characteristics, but they also have significant limitations. Multimode interference (MMI) couplers achieve broadband optical power distribution by utilizing multi-mode interference effects, but the non-uniformity of output power and additional losses limit the improvement of their actual performance. Traditional symmetrical directional couplers perform well in narrowband applications due to their low loss and flexible splitting ratio control capabilities, but due to limited bandwidth and sensitivity to manufacturing tolerances, they face great challenges in high-density integration and broadband applications. Summary of the invention
[0003] In view of this, the embodiments of the present application provide a four-port beam splitter, an optical module and an output light splitting ratio adjustment method, which at least partially solve the problem of bandwidth limitation and sensitivity to manufacturing tolerances of the symmetrical directional coupler used in the power splitter in the prior art.
[0004] In a first aspect, an embodiment of the present application provides a four-port beam splitter, wherein the four-port beam splitter is configured as a bidigital structure, the four-port beam splitter comprises a first input waveguide, a second input waveguide, a first output waveguide, a second output waveguide and a coupling waveguide, the coupling waveguide comprises an input coupling region waveguide, a transition region waveguide and an output coupling region waveguide connected in sequence, the first input waveguide and the second input waveguide are arranged in parallel along a light propagation direction, the first output waveguide and the second output waveguide are arranged in parallel along the light propagation direction, the input coupling region waveguide is located between the first input waveguide and the second input waveguide, the output coupling region waveguide is located between the first output guide and the second output guide, and at least one of the input coupling region waveguide and the output coupling region waveguide is configured as a structure in which the width of the waveguide gradually decreases in a direction toward an end.
[0005] According to a specific implementation of the embodiment of the present application, the structure in which the width of the waveguide gradually decreases in the direction toward the end is a first tapered structure.
[0006] According to a specific implementation of the embodiment of the present application, the first tapered structure is configured as a structure in which multiple sections of tapered waveguides with different slopes are connected in sequence.
[0007] According to a specific implementation of the embodiment of the present application, at least one of the first input waveguide and the second input waveguide includes an input single-mode waveguide and an input tapered waveguide connected in sequence along the light propagation direction, the input tapered waveguide is coupled with the input coupling region waveguide, and the input tapered waveguide is set to a second tapered structure.
[0008] According to a specific implementation of the embodiment of the present application, at least one of the first output waveguide and the second output waveguide includes an output tapered waveguide and an output single-mode waveguide connected in sequence along the light propagation direction, the output tapered waveguide is coupled with the output coupling region waveguide, and the output tapered waveguide is set to a third tapered structure.
[0009] According to a specific implementation of the embodiment of the present application, the minimum widths of the second conical structure and the third conical structure are both greater than 200 nm.
[0010] According to a specific implementation of the embodiment of the present application, the minimum width of the first conical structure is greater than 200 nm.
[0011] According to a specific implementation of the embodiment of the present application, the distance between the input coupling region waveguide and the first input waveguide and the distance between the input coupling region waveguide and the second input waveguide are both greater than 200 nm, and the distance between the output coupling region waveguide and the first output waveguide and the distance between the output coupling region waveguide and the second output waveguide are both greater than 200 nm.
[0012] In a second aspect, an embodiment of the present application further provides an optical module, comprising a four-port beam splitter as described in any embodiment of the first aspect above.
[0013] In a third aspect, an embodiment of the present application further provides a method for adjusting an output light splitting ratio, using a four-port beam splitter as described in any embodiment of the first aspect above, the method comprising:
[0014] adjusting the distance between the input coupling region waveguide and the first input waveguide or the second input waveguide to adjust the output light splitting ratio; and / or,
[0015] The output light splitting ratio is adjusted by adjusting the distance between the output coupling region waveguide and the first output waveguide or the second output waveguide.
[0016] Beneficial effects:
[0017] The four-port beam splitter, optical module and output light splitting ratio adjustment method in the embodiments of the present application can achieve flat spectrum output of arbitrary splitting ratio in the case of two-port input by designing a double-finger structure and adjusting the parameters of the double-finger structure, thereby improving the performance of the optical device; the use of a double-finger coupling structure can minimize the impact of manufacturing process deviations on device performance; the device output spectrum is relatively flat, which can solve the strong wavelength-related characteristics of traditional directional couplers; the process requirements are low, reducing the dependence on processing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] 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.
[0019] Figure 1 is a schematic structural diagram of a four-port beam splitter according to an embodiment of the present invention;
[0020] Figure 2 is a schematic diagram of the working principle of a four-port beam splitter according to an embodiment of the present invention;
[0021] Figure 3 A schematic diagram of adjusting the ratio of gap1 to gap2 according to an embodiment of the present invention;
[0022] Figure 4 A schematic diagram of adjusting the ratio of gap3 to gap4 according to an embodiment of the present invention;
[0023] Figure 5 is an output simulation diagram when gap1 / gap2=1 according to an embodiment of the present invention;
[0024] Figure 6 is an output simulation diagram when gap1 / gap2=0.75 according to an embodiment of the present invention;
[0025] Figure 7 is an output simulation diagram when gap1 / gap2=0.5 according to an embodiment of the present invention;
[0026] Figure 8 is an output simulation diagram when gap1 / gap2=0.4 according to an embodiment of the present invention;
[0027] In the figure: 1. first input single-mode waveguide; 2. second input single-mode waveguide; 3. first output single-mode waveguide; 4. second output single-mode waveguide; 5. first input tapered waveguide; 6. second input tapered waveguide; 7. first output tapered waveguide; 8. second output tapered waveguide; 9. input coupling region waveguide; 10. transition region waveguide; 11. output coupling region waveguide. DETAILED DESCRIPTION
[0028] The embodiments of the present application are described in detail below with reference to the accompanying drawings.
[0029] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.
[0030] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.
[0031] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show the components related to the present application rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.
[0032] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.
[0033] Directional couplers composed of asymmetric structures have shown superior performance in solving the above problems. The asymmetric design effectively demonstrates the flattened optical power response characteristics in a wide wavelength range through the asymmetric distribution of waveguide geometry and mode characteristics, significantly broadening the operating bandwidth. At the same time, the asymmetric coupler design significantly improves the tolerance to manufacturing tolerances and reduces the dependence on processing accuracy by optimizing the waveguide mode matching characteristics.
[0034] In the first aspect, based on the characteristics of the asymmetric structure described above, the present application embodiment provides a four-port beam splitter, as shown below. Figures 1 to 8 Describe in detail.
[0035] In one embodiment, referring to Figure 1 , the four-port beam splitter is set to a double-digit structure, the four-port beam splitter includes a first input waveguide (waveguide corresponding to port 1), a second input waveguide (waveguide corresponding to port 2), a first output waveguide (waveguide corresponding to port 3), a second output waveguide (waveguide corresponding to port 4) and a coupling waveguide, the coupling waveguide includes an input coupling region waveguide 9, a transition region waveguide 10 and an output coupling region waveguide 11 connected in sequence, the first input waveguide and the second input waveguide are arranged in parallel along the light propagation direction, the first output waveguide and the second output waveguide are arranged in parallel along the light propagation direction, the input coupling region waveguide 9 is located between the first input waveguide and the second input waveguide, the output coupling region waveguide 11 is located between the first output guide and the second output guide, and at least one of the input coupling region waveguide 9 and the output coupling region waveguide 11 is set to a structure in which the width of the waveguide gradually decreases along the direction toward the end.
[0036] Specifically, by designing a double-finger structure and adjusting the parameters of the double-finger structure, a flat spectrum output with arbitrary splitting ratio can be achieved in the case of two-port input, thereby improving the performance of the optical device; the use of a double-finger coupling structure can minimize the impact of manufacturing process deviations on device performance; the device output spectrum is flatter, which can solve the strong wavelength-related characteristics of traditional directional couplers; the process requirements are low, reducing the dependence on processing accuracy.
[0037] In this embodiment, a flat spectrum output with any splitting ratio can be achieved by adjusting the position of the input coupling region waveguide 9 between the first input waveguide and the second input waveguide, or adjusting the position of the output coupling region waveguide 11 between the first output waveguide and the second output waveguide.
[0038] In one embodiment, the structure in which the width of the waveguide gradually decreases toward the end is a first tapered structure. Preferably, the first tapered structure is configured as a structure in which multiple tapered waveguides with different slopes are connected in sequence.
[0039] In this embodiment, by setting the two ends of the coupling region waveguide as a structure in which multiple sections of tapered waveguides with different slopes are connected in sequence, the device performance can be achieved through a shorter coupling waveguide structure, thereby reducing the device size and improving the flexibility of the device in high-density integrated applications; and due to the structural setting, the device output spectrum is relatively flat, which can solve the strong wavelength-related characteristics of traditional directional couplers.
[0040] In one embodiment, at least one of the first input waveguide and the second input waveguide comprises an input single-mode waveguide and an input tapered waveguide sequentially connected along the light propagation direction, the input tapered waveguide is coupled with the input coupling region waveguide, and the input tapered waveguide is arranged as a second tapered structure.
[0041] Further, at least one of the first output waveguide and the second output waveguide includes an output tapered waveguide and an output single-mode waveguide sequentially connected along the light propagation direction, the output tapered waveguide is coupled with the output coupling region waveguide, and the output tapered waveguide is configured as a third tapered structure.
[0042] Specifically, Figure 1 The two left ports in the figure are input single-mode waveguides (first input single-mode waveguide 1 and second input single-mode waveguide 2), which gradually narrow in the width direction to the coupling region through tapered waveguides (first input tapered waveguide 5 and second input tapered waveguide 6), and couple with the input coupling region waveguide 9 to form a double-finger structure. The input coupling region waveguide 9 and the output coupling region waveguide 11 are connected by a transition waveguide 10. The output coupling region waveguide 11 couples light to the output single-mode waveguide (first output single-mode waveguide 3 and second output single-mode waveguide 4) through tapered waveguides (first output tapered waveguide 7 and second output tapered waveguide 8), thereby realizing optical power output with different splitting ratios.
[0043] The input coupling region waveguide 9 and the output coupling region waveguide 11 can be set to a symmetrical or asymmetrical structure. In addition, the input coupling region waveguide 9 or the output coupling region waveguide 11 can be formed by connecting multiple sections of tapered waveguides with different slopes, such as Figure 1 Shown in the dashed box.
[0044] In one embodiment, the minimum widths of the second tapered structure and the third tapered structure are both greater than 200 nm. The minimum width of the first tapered structure is greater than 200 nm. In this embodiment, due to the use of a bidigital structure design, the minimum width W of the waveguide of each tapered structure is greater than 200 nm, which has low process requirements, reduces dependence on processing accuracy, and improves tolerance to manufacturing tolerances.
[0045] In one embodiment, the distance between the input coupling region waveguide 9 and the first input waveguide and the distance between the input coupling region waveguide 9 and the second input waveguide are both greater than 200 nm, and the distance between the output coupling region waveguide 11 and the first output waveguide and the distance between the output coupling region waveguide 11 and the second output waveguide are both greater than 200 nm. In this embodiment, due to the use of a bidigital structure design, the distance between the coupling region waveguide and the output waveguide or the input waveguide can be greater than 200 nm, so the structure of the device has low process requirements, reduces dependence on processing accuracy, and improves tolerance to manufacturing tolerances.
[0046] The working principle of the four-port beam splitter in the embodiment of the present application is as follows:
[0047] Evanescent field is a special phenomenon in the transmission process of light in waveguide structure. When light propagates in the waveguide, part of the light energy will penetrate to the outside of the waveguide to form an evanescent field. The intensity of the evanescent field decays rapidly as the distance from the waveguide surface increases. Two adjacent waveguides can achieve light coupling through the evanescent field.
[0048] Reference Figures 2 to 4 The coupling coefficients of the output coupling region waveguide 11 to the first output tapered waveguide 7 and the second output tapered waveguide 8 are K 1 , K 2 The coupling coefficients of the first output tapered waveguide 7 and the second output tapered waveguide 8 to the output coupling region waveguide 11 are K' respectively. 1 , K' 2 , as the distance between the two waveguides increases in the device length direction, K 1 >K' 1 And K 2 >K' 2 , the output optical power will gradually concentrate in the upper and lower ports, thus realizing the splitting function.
[0049] By adjusting the gap1 between the first output tapered waveguide 7 and the output coupling region waveguide 11, or adjusting the gap2 between the second output tapered waveguide 8 and the output coupling region waveguide 11, the output of any beam splitting ratio can be achieved. When gap1=gap2, the output power of the two output ports is the same; when gap1 increases, the output optical power of port 3 will decrease accordingly, and the normalized output optical powers of port 3 and port 4 are respectively:
[0050]
[0051] Where K is a constant related to the waveguide structure and material, P 端口3 is the normalized output optical power of port 3, P 端口4 is the normalized output optical power of port 4.
[0052] Similarly, refer to Figure 4 As shown, by changing the gap3 between the input coupling region waveguide 9 and the first input tapered waveguide 5 and the gap4 between the input coupling region waveguide 9 and the second input tapered waveguide 6, the optical power output of any splitting ratio can be achieved. When gap3 increases, the output optical power of port 3 will decrease accordingly. When gap4 increases, the output optical power of port 4 will decrease accordingly.
[0053] For different ratios of gap1 to gap2, refer to the simulation results for the change in the optical power splitting ratio of the output light. Figures 5 to 8 . It can be seen from the simulation results in the figure that the output of the power divider with different splitting ratios can be achieved by controlling the ratio of the output port gap1 / gap2; when gap1 / gap2=1, it corresponds to a 50%:50% optical power splitting ratio; when gap1 / gap2=0.4, it corresponds to a 90%:10% optical power splitting ratio. In this embodiment, only the ratio of gap1 to gap2 is adjusted to achieve different output light optical power splitting ratios. In actual application, the ratio of gap3 to gap4 can also be adjusted to achieve different output light optical power splitting ratios, or the ratio of gap1 to gap2 and the ratio of gap3 to gap4 can be adjusted at the same time to achieve different output light optical power splitting ratios. The appropriate adjustment scheme can be selected according to actual needs.
[0054] In a second aspect, an embodiment of the present application further provides an optical module, comprising a four-port beam splitter as described in any embodiment of the first aspect above.
[0055] In a third aspect, an embodiment of the present application further provides a method for adjusting an output light splitting ratio, using a four-port beam splitter as described in any embodiment of the first aspect above, the method comprising:
[0056] Adjusting the distance between the input coupling region waveguide 9 and the first input waveguide or the second input waveguide to adjust the output light splitting ratio; and / or,
[0057] The output light splitting ratio is adjusted by adjusting the distance between the output coupling region waveguide 11 and the first output waveguide or the second output waveguide.
[0058] In this embodiment, by adjusting the position of the input coupling region waveguide 9 between the first input waveguide and the second input waveguide, or adjusting the position of the output coupling region waveguide 11 between the first output waveguide and the second output waveguide, a flat spectrum output with any splitting ratio can be achieved. The specific adjustment method refers to the working principle of the four-port beam splitter described in the first aspect, which will not be described in detail here.
[0059] The embodiment provided by the present invention can realize a flat spectrum output with any splitting ratio under the condition of two-port input by setting a double-finger structure. At the same time, the use of a double-finger coupling structure can minimize the impact of manufacturing process deviation on device performance; the device output spectrum is relatively flat, which can solve the strong wavelength-related characteristics of traditional directional couplers; because the minimum width W of each tapered waveguide is greater than 200nm, and the gap between each waveguide is greater than 200nm, low process requirements are achieved and the dependence on processing accuracy is reduced.
[0060] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.
Claims
1. A four-port beam splitter, characterized in that: The four-port beam splitter is arranged as a bidigital structure, comprising a first input waveguide, a second input waveguide, a first output waveguide, a second output waveguide and a coupling waveguide, wherein the coupling waveguide comprises an input coupling region waveguide (9), a transition region waveguide (10) and an output coupling region waveguide (11) which are connected in sequence, wherein the first input waveguide and the second input waveguide are arranged in parallel along a light propagation direction, wherein the first output waveguide and the second output waveguide are arranged in parallel along a light propagation direction, wherein the input coupling region waveguide (9) is located between the first input waveguide and the second input waveguide, wherein the output coupling region waveguide (11) is located between the first output waveguide and the second output waveguide, and wherein at least one of the input coupling region waveguide (9) and the output coupling region waveguide (11) is arranged as a structure in which the width of the waveguide gradually decreases in a direction toward an end.
2. The four-port beam splitter according to claim 1, characterized in that: The structure in which the width of the waveguide gradually decreases toward the end is a first tapered structure.
3. The four-port beam splitter according to claim 2, characterized in that: The first tapered structure is configured as a structure in which multiple sections of tapered waveguides with different slopes are connected in sequence.
4. The four-port beam splitter according to claim 1, characterized in that: At least one of the first input waveguide and the second input waveguide comprises an input single-mode waveguide and an input tapered waveguide connected in sequence along the light propagation direction, the input tapered waveguide is coupled with the input coupling region waveguide (9), and the input tapered waveguide is arranged as a second tapered structure.
5. The four-port beam splitter according to claim 4, characterized in that: At least one of the first output waveguide and the second output waveguide comprises an output tapered waveguide and an output single-mode waveguide sequentially connected along a light propagation direction, the output tapered waveguide is coupled with the output coupling region waveguide (11), and the output tapered waveguide is arranged as a third tapered structure.
6. The four-port beam splitter according to claim 5, characterized in that: The minimum widths of the second tapered structure and the third tapered structure are both greater than 200 nm.
7. The four-port beam splitter according to claim 2, characterized in that: The minimum width of the first cone-shaped structure is greater than 200 nm.
8. The four-port beam splitter according to claim 1, characterized in that: The distance between the input coupling region waveguide (9) and the first input waveguide and the distance between the input coupling region waveguide (9) and the second input waveguide are both greater than 200 nm, and the distance between the output coupling region waveguide (11) and the first output waveguide and the distance between the output coupling region waveguide (11) and the second output waveguide are both greater than 200 nm.
9. An optical module, characterized in that: Comprising the four-port beam splitter as described in any one of claims 1-8.
10. A method for adjusting the output light splitting ratio of the four-port beam splitter according to any one of claims 1 to 8, characterized in that: The method comprises: adjusting the distance between the input coupling region waveguide (9) and the first input waveguide or the second input waveguide to adjust the output light splitting ratio; and / or, The output light splitting ratio is adjusted by adjusting the distance between the output coupling region waveguide (11) and the first output waveguide or the second output waveguide.