Wavelength division multiplexer and fiber optic communication system

Abstract

The application provides a wavelength division multiplexer and an optical fiber communication system. The wavelength division multiplexer comprises a bus waveguide, a stub waveguide, a plurality of ring waveguides and a silica substrate. The bus waveguide comprises an input end and a first coupling section. The plurality of ring waveguides are arranged around the first coupling section. The cross section of each ring waveguide intersects with the axis of the first coupling section. The included angle between the cross section of each ring waveguide and the cross section of the adjacent ring waveguide of the ring waveguide is the same. The stub waveguide is arranged between the first coupling section and the ring waveguide. One ring waveguide corresponds to one stub waveguide. The stub waveguide is evanescently coupled with the first coupling section. The stub waveguide is evanescently coupled with the ring waveguide corresponding to the stub waveguide. The spacing distance between each ring waveguide and the bus waveguide is the same. The bus waveguide penetrates through the silica substrate. Each ring waveguide is provided with an output end. The application can reduce the area of the wavelength division multiplexer.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a wavelength division multiplexer and an optical fiber communication system. Background Technology

[0002] A wavelength division multiplexer is an optical communication device that uses wavelength division multiplexing technology to combine optical signals of different wavelengths onto a single optical fiber for transmission at the transmitting end, and then separates the optical signals at the receiving end, thereby significantly increasing the transmission capacity of optical fibers.

[0003] Existing wavelength division multiplexers (WDMs) consist of an input waveguide, multiple output waveguides, and a shallow-etched multimode interference coupler (SMAC). The WDM coupler splits the light into multiple wavelengths via the SMAC structure, and then outputs the light sequentially through the output terminals. However, different wavelengths of light accumulate different phase differences within the SMAC, resulting in different self-image positions. Since multiple wavelengths of input light are sequentially split within the SMAC structure, the output terminals are arranged sequentially along the length of the SMAC structure. However, as the number of input wavelengths increases, the number of output ports increases, and the length of the SMAC structure also increases with the number of output ports. This increases the area of ​​the WDM, making it difficult to meet the compact design requirements of photonic integrated circuits. Summary of the Invention

[0004] The primary objective of this invention is to provide a compact wavelength division multiplexer.

[0005] A second objective of this invention is to provide an optical fiber communication system that utilizes the aforementioned wavelength division multiplexer.

[0006] To achieve the first objective of this invention, the present invention provides a wavelength division multiplexer (WDM), comprising a bus waveguide, a short-section waveguide, multiple ring waveguides, and a silicon dioxide substrate; the number of ring waveguides is greater than or equal to two; the bus waveguide includes an input terminal and a first coupling segment, the multiple ring waveguides are arranged around the first coupling segment, the axis of the first coupling segment is located on the plane of the cross-section of the ring waveguide, and the included angle between the cross-sections of any two adjacent ring waveguides is the same; a short-section waveguide is arranged between the first coupling segment and the ring waveguides, one ring waveguide corresponds to one short-section waveguide, the short-section waveguide is evanescently coupled to the first coupling segment, and the short-section waveguide is evanescently coupled to the ring waveguide corresponding to the short-section waveguide; the ring waveguides are spaced at the same distance from the bus waveguides; the bus waveguides pass through the silicon dioxide substrate; each ring waveguide is provided with an output terminal.

[0007] As can be seen from the above scheme, by adjusting the length of the short-section waveguide and the radius of the ring waveguide, each ring waveguide can respond to a specific wavelength. Because the coupling coefficient is adjusted via the short-section waveguide, each ring waveguide can couple with the bus waveguide within a single region of the bus waveguide, thus achieving beam splitting, instead of arranging multiple outputs along the bus waveguide. This reduces the area of ​​the wavelength division multiplexer and meets the compact design requirements of photonic integrated circuits.

[0008] In a further embodiment, the short-section waveguide includes a parallel coupling section, a transition section, and a ring coupling section. The parallel coupling section is arranged parallel to the first coupling section. A transition section is provided at both ends of the parallel coupling section. The first end of each transition section is connected to the parallel coupling section, and the second end of each transition section is connected to a ring coupling section. The transition section extends into the ring waveguide.

[0009] In a further proposed scheme, the parallel coupling segment is evanescently coupled to the first coupling segment, and the ring coupling segment is evanescently coupled to the ring waveguide.

[0010] In a further proposed scheme, the length of the parallel coupling segment is related to the coupling coefficient.

[0011] Therefore, by adjusting the length of the short-section waveguide, the coupling coefficient can be decoupled from the spacing between the bus waveguide and the ring waveguide. In this invention, the spacing between each ring waveguide and the bus waveguide is the same, and the length is adjusted only by the short-section waveguide. Therefore, the error generated when adjusting the spacing between the ring waveguide and the bus waveguide can be reduced.

[0012] In a further embodiment, each ring waveguide corresponds to a communication channel; input light is input from the input end, and each ring waveguide receives input light of the wavelength corresponding to the communication channel of the ring waveguide; the communication channel of each ring waveguide is not adjacent to the communication channels of the adjacent ring waveguides.

[0013] Therefore, the communication channels of each ring waveguide are not adjacent to the communication channels of the adjacent ring waveguides, thereby reducing signal crosstalk between each adjacent ring waveguide.

[0014] In a further design, each ring waveguide is covered with a heater.

[0015] As can be seen, each ring waveguide is covered with a heater, and each heater applies a different current, resulting in each ring waveguide receiving a different amount of heat, so that each ring waveguide can only respond to its corresponding specific wavelength.

[0016] In a further design, the light propagation direction at the output end of each ring waveguide is different.

[0017] As can be seen, the light propagation direction at the output end of each ring waveguide is different, which eliminates the waveguide crossings and curved wiring that need to be separated in the output port of the planar structure, thus meeting the compact design requirements of photonic integrated circuits.

[0018] In a further design, the input end is a linear conical structure.

[0019] Therefore, it can be seen that the linear tapered structure can prevent energy loss when the input light of the optical fiber enters the bus waveguide due to changes in the width of the waveguide.

[0020] To achieve the second objective, the present invention provides an optical fiber communication system that utilizes the aforementioned wavelength division multiplexer. Attached Figure Description

[0021] Figure 1 This is a structural diagram of an embodiment of the wavelength division multiplexer of the present invention.

[0022] Figure 2 This is an exploded view of the structure of an embodiment of the wavelength division multiplexer of the present invention.

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0024] The wavelength division multiplexer provided by this invention uses multiple ring waveguides to surround a first coupling segment and short-section waveguides to evanescently couple with the first coupling segment and evanescently couple with the corresponding ring waveguides, thereby reducing the area of ​​the wavelength division multiplexer and meeting the compact design requirements of photonic integrated circuits.

[0025] Wavelength division multiplexer examples: See Figure 1 The wavelength division multiplexer of this embodiment includes a bus waveguide 11, a short-section waveguide 13, multiple ring waveguides 14, and a silicon dioxide substrate 12. The silicon dioxide substrate 12 serves as a physical substrate for support. The bus waveguide 11 passes through the silicon dioxide substrate 12. The number of ring waveguides 14 is greater than or equal to two; the number of ring waveguides 14 can be 2, 4, 6, or 8. In this embodiment, 8 ring waveguides 14 are used as an example.

[0026] See Figure 2 The bus waveguide 11 includes an input terminal 111 and a first coupling segment 112. Multiple ring waveguides 14 are arranged around the first coupling segment 112. The axis of the first coupling segment 112 lies on the plane containing the cross-section of the ring waveguides, and the included angle between the cross-sections of any two adjacent ring waveguides 14 is the same. The ring waveguides 14 are made of silicon. The bus waveguide 11 is also made of silicon.

[0027] A short-section waveguide 13 is disposed between the first coupling segment 112 and the ring waveguide 14. One ring waveguide 14 corresponds to one short-section waveguide 13. The short-section waveguide 13 is evanescently coupled to the first coupling segment 112, and the short-section waveguide 13 is evanescently coupled to the corresponding ring waveguide 14. Specifically, the short-section waveguide 13 includes a parallel coupling segment 131, a transition segment 132, and a ring coupling segment 133.

[0028] The parallel coupling segment 131 is arranged parallel to the first coupling segment 112, so the parallel coupling segment 131 and the first coupling segment 112 are ephemerally coupled. The length of the parallel coupling segment 131 is related to the coupling coefficient, which stems from the power transfer mechanism of the directional coupler based on coupling mode theory, i.e. ,in, The coupling length of parallel coupling segment 131. For the fully coupled length, For the coupling power ratio, when At this time, The power of the input light is completely transferred from one waveguide to another. Where C is the coupling coefficient per unit length, which is determined by the overlap integral of the attenuation fields of the two waveguide modes.

[0029] In a traditional ring waveguide, without a short-section waveguide 13, the first coupling coefficient of the traditional micro-ring modulator is related to the first spacing distance between the strip waveguide and the first ring waveguide of the traditional micro-ring modulator, i.e. ,in, The coupling coefficient of a traditional micro-ring modulator, The attenuation coefficient is... The first spacing is 200 nanometers. When the first spacing produces an error of 10 nanometers, the coupling coefficient of the traditional micro-ring modulator changes exponentially with a large slope, and the error is large due to the large first spacing.

[0030] In this embodiment, the spacing between each ring waveguide 14 and the bus waveguide 11 is the same. The spacing between the ring waveguide 14 and the bus waveguide 11 is based on the plane where the ring waveguide 14 is located. The minimum distance between the ring waveguide 14 and the bus waveguide 11 is the spacing between the ring waveguide 14 and the bus waveguide 11.

[0031] In this embodiment, the spacing between the ring waveguide 14 and the bus waveguide 11 is not adjusted; the coupling coefficient is adjusted only through the parallel coupling section 131, based on the formula of the power transfer mechanism of the directional coupler based on coupling mode theory. It can be seen that the function The slope is relatively gentle, and when the parallel coupling segment 131 produces an error of 10 nanometers, its power change is not significant, so the error is small. Therefore, in this embodiment, the spacing between all ring waveguides and bus waveguides is kept consistent, and the error is reduced only by adjusting the length of the short section waveguide corresponding to each ring waveguide.

[0032] A transition section 132 is provided at both ends of the parallel coupling section 131. The first end of each transition section 132 is connected to the parallel coupling section 131, and the second end of each transition section 132 is connected to a ring coupling section 133. The transition section 132 extends into the ring waveguide 14, so the transition section can be evanescently coupled to the ring waveguide 14.

[0033] After the input light is coupled to the parallel coupling section 131 through the first coupling section 112, it is transmitted to the two ring coupling sections 133 through the transition section 132. The ring coupling sections 133 are coupled to the ring waveguide 14, and the input light is transmitted to the ring waveguide 14.

[0034] The lengths of the parallel coupling section 131 and the annular coupling section 133 can be designed independently. The parallel coupling section 131 controls the power entering the short section waveguide 13 from the bus waveguide 11, and the annular coupling section 133 controls the power entering the annular waveguide 14.

[0035] Each ring waveguide 14 corresponds to a communication channel; input light is input from the input terminal 111, and each ring waveguide 14 receives input light of the wavelength corresponding to the communication channel of the ring waveguide 14. In this embodiment, eight ring waveguides are provided, wherein the input light can be input light containing eight wavelengths, specifically, the eight wavelengths are λ1=1562nm, λ2=1560nm, λ3=1558nm, λ4=1556nm, λ5=1554nm, λ6=1552nm, λ7=1550nm and λ8=1548nm. Each ring waveguide 14 receives input light of the wavelength corresponding to its communication channel. For example, input light with wavelength λ1 = 1562 nm corresponds to communication channel 1, input light with wavelength λ2 = 1560 nm corresponds to communication channel 2, input light with wavelength λ3 = 1558 nm corresponds to communication channel 3, input light with wavelength λ4 = 1556 nm corresponds to communication channel 4, input light with wavelength λ5 = 1554 nm corresponds to communication channel 5, input light with wavelength λ6 = 1552 nm corresponds to communication channel 6, input light with wavelength λ7 = 1550 nm corresponds to communication channel 7, and input light with wavelength λ8 = 1548 nm corresponds to communication channel 8. The communication channels of each ring waveguide 14 are not adjacent to the communication channels of adjacent ring waveguides 14. That is, the order of the communication channels of each ring waveguide 14 is 1, 5, 3, 7, 2, 6, 4, 8.

[0036] The response of the ring waveguide 14 to a specific wavelength is determined by the radius of the ring. When the communication channel of each ring waveguide 14 is adjacent to the communication channel of its neighboring ring waveguide 14, the sizes of the ring waveguides 14 are arranged in a clockwise direction, causing the larger ring waveguides 14 to be too close together, thus generating crosstalk. In this embodiment, the communication channel of each ring waveguide 14 is not adjacent to the communication channel of its neighboring ring waveguide 14, allowing the larger and smaller ring waveguides to be mixed and arranged, thereby increasing the distance between the ring waveguides and reducing the generation of crosstalk.

[0037] Each ring waveguide 14 is covered with a heater 143; for example, a heater corresponding to one ring waveguide 14 is attached to the surface of the ring waveguide 14. By measuring the power of the input light output at the output terminal 142 of each ring waveguide 14, and then independently adjusting the current of each heater, each ring waveguide 14 can only respond to its corresponding specific wavelength.

[0038] The light propagation direction of the output terminals 142 of each ring waveguide 14 is different, which eliminates the waveguide crossings and curved wiring that need to be separated in the output port of the planar structure, and meets the requirements of compact design for photonic integrated circuits.

[0039] Each ring waveguide 14 is provided with an output terminal 142. The ring waveguide 14 is used to couple with the ring coupling section 133, and the output terminal 142 outputs the input light received by the ring waveguide 14.

[0040] The input terminal 111 has a linear tapered structure. The linear tapered structure ensures that when the input light from the optical fiber enters the bus waveguide, the energy will not be lost due to the change in the width of the waveguide.

[0041] The adjustable parameters of the wavelength division multiplexer in this embodiment include the length of the parallel coupling section 131, the length of the ring coupling section 133, the radius of the ring waveguide 14, and the current of the heater. The radius of the ring waveguide 14 can adjust the response wavelength, the length of the parallel coupling section 131 and the length of the ring coupling section 133 can adjust the coupling coefficient, and the current of the heater can adjust the thermal offset.

[0042] By adjusting the coupling coefficient through short-section waveguides, each ring waveguide can couple with the bus waveguide within a region of the bus waveguide, thus achieving beam splitting. Furthermore, the length of the bus waveguide is determined by the longest short-section waveguide, rather than the length of multiple output terminals arranged along the bus waveguide, thereby reducing the area of ​​the wavelength division multiplexer and meeting the compact design requirements of photonic integrated circuits.

[0043] Example of an optical fiber communication system: The optical fiber communication system uses the wavelength division multiplexer of the above embodiments, thereby reducing the size of the optical fiber communication system.

[0044] The above are merely preferred embodiments of the present invention, but the design concept of the invention is not limited thereto. Without departing from the concept of the present invention, many other equivalent embodiments may be included. Those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the protection scope of the present invention.

Claims

1. A wavelength division multiplexer, characterized in that, The wavelength division multiplexer includes a bus waveguide, a short-section waveguide, multiple ring waveguides, and a silicon dioxide substrate; The number of the ring waveguides is greater than or equal to two; The bus waveguide includes an input terminal and a first coupling segment. A plurality of ring waveguides are arranged around the first coupling segment. The axis of the first coupling segment is located on the plane of the cross-section of the ring waveguide. The included angle between the cross-sections of any two adjacent ring waveguides is the same. A short-section waveguide is provided between the first coupling segment and the ring waveguide, with one short-section waveguide corresponding to one ring waveguide. The short-section waveguide is evanescently coupled to the first coupling segment, and the short-section waveguide is evanescently coupled to the ring waveguide corresponding to the short-section waveguide. The spacing between each of the ring waveguides and the bus waveguide is the same; The bus waveguide passes through the silicon dioxide substrate; Each of the aforementioned ring waveguides is provided with an output terminal; The short-section waveguide includes a parallel coupling section, a transition section, and a ring coupling section, wherein the parallel coupling section is arranged parallel to the first coupling section; Each end of the parallel coupling segment is provided with a transition segment, the first end of each transition segment is connected to the parallel coupling segment, and the second end of each transition segment is connected to a ring coupling segment. The transition section extends into the ring waveguide; The parallel coupling segment is evanescently coupled to the first coupling segment, and the ring coupling segment is evanescently coupled to the ring waveguide; The length of the parallel coupling segment is related to the coupling coefficient.

2. The wavelength division multiplexer according to claim 1, characterized in that: Each of the aforementioned ring waveguides corresponds to one communication channel; The input light is input from the input terminal, and each of the ring waveguides receives the input light of the wavelength corresponding to the communication channel of the ring waveguide; The communication channel of each ring waveguide is not adjacent to the communication channel of the ring waveguide next to it.

3. The wavelength division multiplexer according to claim 1, characterized in that: Each of the aforementioned ring waveguides is covered with a heater.

4. The wavelength division multiplexer according to claim 1, characterized in that: The light propagation direction at the output end of each of the aforementioned ring waveguides is different.

5. The wavelength division multiplexer according to claim 1, characterized in that: The input terminal has a linear tapered structure.

6. An optical fiber communication system, characterized in that, The optical fiber communication system uses the wavelength division multiplexer according to any one of claims 1 to 5.

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