End face coupler and optical chip

Abstract

The invention discloses an end face coupler and an optical chip, relates to the technical field of integrated optics, and aims to solve the problem that efficient coupling is difficult to realize due to the fact that the horizontal size of the end face coupler cannot be reduced infinitely due to process limitation. The end face coupler comprises a substrate and a coupling waveguide structure. The coupling waveguide structure is arranged on the substrate; the coupling waveguide structure at least comprises a first waveguide part and a second waveguide part which are stacked in the thickness direction of the substrate; the input end of the first waveguide part is the input end of the end face coupler, and the output end of the second waveguide part is the output end of the end face coupler; the output end of the first waveguide part is aligned with the output end of the second waveguide part; the first waveguide part is thinner than the second waveguide part; the input end of the first waveguide part is coupled with the optical fiber, the optical fiber is used for transmitting composite light, the composite light comprises at least two optical signals of different wavebands, and the difference value between the wavelengths of the optical signals of every two different wavebands in the composite light is larger than or equal to 20 nm.

Description

Technical Field

[0001] The present application relates to the field of integrated optical technology, and in particular to an end face coupler and an optical chip. Background Art

[0002] As an important part of modern communication systems, optical communication plays an indispensable role in high-speed data transmission and communication networks. In optical communication systems, end couplers are often used to couple optical signals from external waveguides or optical fibers to optical chips, or from optical chips to external waveguides or optical fibers.

[0003] In order to achieve effective coupling with the single-mode waveguide included in the optical chip, the thickness of the waveguide layer included in the existing end coupler must be consistent with the thickness of the single-mode waveguide coupled with it. In order to achieve effective coupling between the waveguide layer and some composite lights of corresponding bands at the same time, the width of the waveguide layer needs to be narrowed. However, due to the process precision limitations of different process nodes, the width of the waveguide layer cannot be reduced indefinitely, otherwise it will lead to a decrease in yield and an increase in cost. Summary of the invention

[0004] The purpose of the present application is to provide an end face coupler and an optical chip, which are used to solve the problem that the horizontal size of the end face coupler cannot be infinitely reduced due to process limitations, making it difficult to achieve efficient coupling.

[0005] In order to achieve the above-mentioned purpose, in a first aspect, the present application provides an end face coupler comprising: a substrate and a coupling waveguide structure. The coupling waveguide structure is arranged on the substrate, and the tapered waveguide structure at least comprises a first waveguide portion and a second waveguide portion stacked along the thickness direction of the substrate. The input end of the first waveguide portion is the input end of the coupling waveguide structure, and the output end of the second waveguide portion is the output end of the coupling waveguide structure. The output end of the first waveguide portion is aligned with the output end of the second waveguide portion. The thickness of the first waveguide portion is smaller than that of the second waveguide portion. The input end of the first waveguide portion is coupled to an optical fiber for transmitting composite light, and the composite light includes at least two optical signals of different wavelength bands, and the difference between the wavelengths of each two optical signals of different wavelength bands in the composite light is greater than or equal to 20nm.

[0006] In the case of adopting the above scheme, the input end of the first waveguide part is coupled with the optical fiber as the input end of the end coupler, the output end of the second waveguide part is coupled with the waveguide included in the optical chip as the output end of the end coupler, the first waveguide part and the second waveguide part are coupled, the composite light transmitted by the optical fiber into the first waveguide part is transmitted into the second waveguide part, and then transmitted into the waveguide included in the optical chip by the second waveguide part, so as to realize the function of end coupling. The thickness of the second waveguide part is determined by the thickness of the waveguide included in the optical chip coupled thereto, and the thickness of the first waveguide part can be determined together with the width of the first waveguide part by the optical fiber to be coupled, the wavelength of the light transmitted by the optical fiber and the coupling efficiency. The end coupler provided in the present application can realize efficient coupling with the optical fiber coupled to the input end by reducing the thickness of the first waveguide part, with a larger lateral width of the first waveguide part, and the larger lateral width of the first waveguide part meets the minimum characteristic size requirements of a more mature manufacturing process. At this time, a more mature manufacturing process can be used to manufacture the end coupler provided in the present application, which reduces the manufacturing difficulty and improves the yield of the end coupler. In the case where the actual manufacturing size and the design size of the end coupler have a high degree of matching, it can be ensured that the end coupler manufactured using the existing mature process has a working performance that is roughly the same as the theoretical design, and it can be ensured that the end coupler has a high coupling efficiency with the optical fiber and the waveguide included in the optical chip. At the same time, the second waveguide part coupled to the first waveguide part can be efficiently coupled with the waveguide included in the optical chip coupled to the output end of the second waveguide part without reducing the thickness, so as to be greater than the thickness of the first waveguide part and the waveguide included in the optical chip coupled to the output end of the second waveguide part, thereby achieving the purpose of this application. The output end of the first waveguide part and the output end of the second waveguide part are aligned to make the coupling efficiency of the first waveguide part and the second waveguide part higher. The present application solves the problem that the end coupler with a fixed waveguide part thickness in the prior art can only reduce its lateral width, and the lateral width cannot be infinitely reduced, thereby limiting the improvement of the coupling efficiency. At the same time, the present application can also achieve high-efficiency coupling with composite light.

[0007] As a possible implementation, the composite light wavelength range is 630nm to 860nm; the material of the coupling waveguide structure includes silicon nitride. The composite light in this wavelength range is within the visible light range, and the end coupler provided in the present application can be applied to the optical system of visible light. Silicon nitride material is more adaptable to the aforementioned composite light, and the coupling waveguide structure can achieve higher efficiency coupling with the composite light.

[0008] As a possible implementation scheme, the cross-sectional shape of the first waveguide portion is a cone, an inverted cone or a scissors shape. Because the cone, the inverted cone or the scissors shape are relatively simple shapes, the process difficulty is lower when manufacturing the end coupler provided by the present application. There are multiple choices for the cross-sectional shape of the first waveguide portion. Different shapes can be selected according to different optical fibers and different lights transmitted by the optical fibers in specific applications to achieve a better coupling effect, and it is beneficial to improve the applicability of the end coupler provided by the present application in different application scenarios.

[0009] As a possible implementation, the cross-sectional shape of the second waveguide portion is a cone, an inverted cone or a scissors shape. The cross-sectional shape of the second waveguide portion is a cone, an inverted cone or a scissors shape. The beneficial effects of the cross-sectional shape of the first waveguide portion can be referred to, and will not be repeated here.

[0010] As a possible implementation scheme, the cross-sectional shapes of the first waveguide portion and the second waveguide portion are the same, and the cross-sectional area of ​​the second waveguide portion is smaller than the cross-sectional area of ​​the first waveguide portion. The same cross-sectional shapes of the first waveguide portion and the second waveguide portion can make the light be conducted in the first waveguide portion and the second waveguide portion in substantially the same transmission path to reduce light leakage, thereby obtaining a better coupling effect between the first waveguide portion and the second waveguide portion. When manufacturing the end face coupler provided in the present application, the cross-sectional area of ​​the second waveguide portion located on the first waveguide portion is smaller than the former, which can reduce the process difficulty of manufacturing the first waveguide portion and the second waveguide portion, thereby reducing costs.

[0011] As a possible implementation scheme, when the first waveguide portion is an inverted tapered waveguide portion and the wavelength range of the composite light is 630nm to 860nm, the first waveguide portion has a first trapezoidal waveguide region and a first rectangular waveguide region connected to the end with a larger width of the first trapezoidal waveguide region; wherein the thickness of the first waveguide portion is 60nm to 100nm, the width of the end with a smaller width of the first trapezoidal waveguide region is 180nm to 200nm, the width of the end with a larger width of the first trapezoidal waveguide region is 500nm to 1μm, and the length of the first trapezoidal waveguide region along the transmission direction of the composite light is 100μm to 1000μm. When the thickness of the first waveguide portion is within the range of 60nm to 100nm, it can achieve a better coupling effect with the light of the aforementioned wavelength band in combination with the end with a smaller width of the first trapezoidal waveguide region.

[0012] As a possible implementation scheme, when the second waveguide portion is an inverted tapered waveguide portion, and the wavelength range of the composite light is 630nm to 860nm, and the second rectangular waveguide region is connected to the end with the larger width of the second trapezoidal waveguide region; wherein the thickness of the second waveguide portion is 150nm to 800nm, the width of the smaller end of the second trapezoidal waveguide region is 180nm to 200nm, the width of the larger end of the second trapezoidal waveguide region is 500nm to 1μm, and the length of the second trapezoidal waveguide region along the transmission direction of the composite light is 100μm to 1000μm. When the thickness of the second waveguide portion is 150nm to 800nm, and the width of the larger end of the second trapezoidal waveguide region is 500nm to 1μm, that is, the width of the second rectangular waveguide region is 500nm to 1μm, a better coupling effect with the waveguide included in the optical chip can be obtained.

[0013] As a possible implementation, along the transmission direction of the composite light, the thickness of each part of the first waveguide part and / or the second waveguide part is the same. The first waveguide part with equal thickness can make the composite light attenuate less when it is transmitted therein, and the second waveguide part with equal thickness can also make the composite light attenuate less when it is transmitted therein. And the first waveguide part and the second waveguide part with equal thickness are easier to process than the end face coupler using a waveguide with variable thickness.

[0014] As a possible implementation, the length of one end of the first rectangular waveguide area connected to the first trapezoidal waveguide area is equal to the length of one end of the second rectangular waveguide area connected to the second trapezoidal waveguide area. Under the above solution, the coupling effect between the first waveguide portion and the second waveguide portion is better.

[0015] As a possible implementation, the distance between one end of the first rectangular waveguide area connected to the first trapezoidal waveguide area and one end of the second rectangular waveguide area connected to the second trapezoidal waveguide area is 50 μm to 1000 μm. In the above solution, the coupling effect between the first waveguide portion and the second waveguide portion is better.

[0016] As a possible implementation scheme, along the transmission direction of the composite light, the distance between one end of the first trapezoidal waveguide region away from the first rectangular waveguide region and one end of the second trapezoidal waveguide region away from the second rectangular waveguide region is 50 μm to 200 μm. Under the above scheme, the coupling effect between the first waveguide portion and the second waveguide portion is better.

[0017] As a possible implementation scheme, the distance between one end of the first rectangular waveguide region connected to the first trapezoidal waveguide region and one end of the second rectangular waveguide region connected to the second trapezoidal waveguide region is A; along the transmission direction of the composite light, the distance between one end of the first rectangular waveguide region away from the first trapezoidal waveguide region and one end of the second rectangular waveguide region away from the second trapezoidal waveguide region is B, and B is equal to A. Under the above scheme, the coupling effect between the first waveguide portion and the second waveguide portion is better.

[0018] As a possible implementation, the coupled waveguide structure further includes at least one layer of a third waveguide portion, and along the direction from the first waveguide portion to the second waveguide portion, the thicknesses of the first waveguide portion, the third waveguide portion and the second waveguide portion gradually increase.

[0019] In a second aspect, the present application provides an optical chip, which includes the end face coupler provided by the first aspect and various implementations thereof.

[0020] The beneficial effects of the second aspect and its various implementations in this application can be referred to the analysis of the beneficial effects of the first aspect and its various implementations, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0022] Figure 1 This is an axonometric diagram of an embodiment of the present application;

[0023] Figure 2 A top view of the coupling waveguide structure and the optical fiber coupled in the embodiment of the present application;

[0024] Figure 3 A side view of the coupling waveguide structure and the optical fiber included in the embodiment of the present application;

[0025] Figure 4 An axonometric view of the cladding included in the embodiment of the present application;

[0026] Figure 5 The electric field distribution diagrams at different positions of the embodiments of the present application;

[0027] Figure 6 This is a graph showing the change in the overlap integral of the composite light when the end face coupler provided by the embodiment of the present application has different first waveguide portion thicknesses.

[0028] Reference numerals:

[0029] 100-substrate, 200-first waveguide portion,

[0030] 201-first trapezoidal waveguide region, 202-first rectangular waveguide region,

[0031] 300 - second waveguide portion, 301 - second trapezoidal waveguide region,

[0032] 302-second rectangular waveguide region, 400-optical fiber,

[0033] 501-first cladding, 502-second cladding. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0035] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0037] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0038] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] In an optical communication system, an end coupler is used to couple an optical signal from an external waveguide or optical fiber 400 to an optical chip. In order to simultaneously obtain a higher coupling efficiency with the composite light and a higher coupling efficiency with the waveguide included in the optical chip, the geometric dimensions of the waveguide portion of the end coupler perpendicular to the light transmission direction need to be minimized. However, due to the precision limitations of the process node and the processing capability limitations of the material, the dimensions of the cross section of the waveguide portion perpendicular to the light transmission direction must be greater than the minimum feature size required by the process, otherwise it will lead to an increase in cost and a decrease in yield.

[0040] To solve the above problems, in the first aspect, the present application provides an end face coupler. Figure 1, the end face coupler provided in the embodiment of the present application includes: a substrate 100 and a coupling waveguide structure. The coupling waveguide structure is arranged on the substrate 100, and the coupling waveguide structure includes a first waveguide part 200 and a second waveguide part 300 arranged on the first waveguide part 200. The input end of the first waveguide part 200 is the input end of the end face coupler coupled with the optical fiber 400 transmitting the composite light, and the output end of the second waveguide part 300 is the output end of the end face coupler coupled with the waveguide included in the optical chip, the output end of the first waveguide part 200 and the output end of the second waveguide part 300 are aligned, and the composite light includes at least two optical signals of different wavelength bands, and the difference between the wavelengths of each two optical signals of different wavelength bands in the composite light is greater than or equal to 20nm. The thickness of the first waveguide part 200 is less than that of the second waveguide part 300.

[0041] If you use the above solution, please refer to Figure 1 , the first waveguide part 200 is coupled with the optical fiber 400, and the composite light transmitted in the optical fiber 400 is transmitted into the first waveguide part 200; the first waveguide part 200 is coupled with the second waveguide part 300, and the composite light is transmitted into the second waveguide part 300; the second waveguide part 300 is coupled with the waveguide included in the optical chip, and the composite light is transmitted into the waveguide included in the optical chip. Through the above-mentioned path, the end face coupler realizes the function of effectively coupling the composite light from the optical fiber 400 to the waveguide included in the optical chip.

[0042] Among them, the thickness of the first waveguide part 200 is less than the thickness of the second waveguide part 300, and when the second waveguide part 300 is thicker and effectively coupled with the waveguide included in the optical chip, and the cross section of the first waveguide part 200 is kept perpendicular to the light transmission direction and has a larger size, the first waveguide part 200 can be effectively coupled with the optical fiber 400, that is, the end coupler can simultaneously achieve effective coupling with the optical fiber 400 and the waveguide included in the optical chip. The cross section of the first waveguide part 200 has a larger size perpendicular to the light transmission direction, which can make the end coupler provided in the embodiment of the present application compatible with the process of larger minimum feature size. The cost of manufacturing the end coupler provided in the embodiment of the present application using this process is usually low, and the yield is high. More semiconductor factories can manufacture it, and higher production and better supply chain stability can be obtained.

[0043] At the same time, the cross section of the first waveguide part 200 has a larger size perpendicular to the light transmission direction, so that the end coupler provided by the present application can use more types of materials, which can effectively avoid the incompatibility between the device structure and the material caused by the larger minimum characteristic size when processing the aforementioned materials due to the various properties of the materials. The processing difficulty of realizing the thickness of the first waveguide part 200 and the second waveguide part 300 is relatively low, and the difficulty is relatively lower than that of reducing the cross section perpendicular to the light transmission direction, and the total cost of manufacturing the device will not increase. And compared with only using a single-layer waveguide, the end coupler provided by the present application has a higher coupling efficiency.

[0044] In actual application, the present application does not limit the material and size of the substrate 100, as long as it can be applied to the end face coupler provided in the embodiment of the present application, such as silicon, silicon dioxide, lithium niobate and indium phosphide. Optionally, the material of the substrate 100 is silicon, and the process of silicon substrate is more mature and the cost is usually lower.

[0045] As for the optical fiber 400 coupled by the end coupler provided in the present application, the present application does not limit its diameter, numerical aperture (NA) and other parameters, as long as the aforementioned composite light can be effectively transmitted. Optionally, the core diameter of the optical fiber 400 is 3.5 μm, and the numerical aperture NA=0.12.

[0046] As for the composite light transmitted by the optical fiber 400 coupled by the end coupler provided in the present application, its wavelength range can be determined according to the actual application scenario. For example, to adapt to the aforementioned optical fiber 400 with a core diameter of 3.5 μm and a numerical aperture NA=0.12, the wavelength range of the composite light is 630 nm to 860 nm. In addition, the wavelength of the composite light can also be 400 nm to 1000 nm.

[0047] As for the material of the coupling waveguide structure, it may include materials such as lithium niobate, aluminum nitride or aluminum oxide. Optionally, the material of the coupling waveguide structure includes silicon nitride, and the coupling waveguide portion of the silicon nitride material has good coupling efficiency with the composite light in the wavelength range of 630nm to 860nm, which is conducive to improving the coupling efficiency of the end coupler provided in the present application.

[0048] Regarding the first waveguide portion 200 and the second waveguide portion 300 included in the coupled waveguide structure, their shapes can be conical, inverted conical, scissor-shaped, or cantilever-shaped. Optionally, the first waveguide portion 200 and the second waveguide portion 300 are both inverted conical, and the cross-sectional area of ​​the second waveguide portion 300 is smaller than the cross-sectional area of ​​the first waveguide portion 200. In this case, the first waveguide portion 200 and the second waveguide portion 300 can respectively obtain better coupling efficiency with the waveguide included in the optical fiber 400 and the optical chip at the same time, and the process is simpler when manufacturing the end face coupler provided in the embodiment of the present application.

[0049] In the case where the first waveguide portion 200 is in an inverted cone shape, please refer to Figure 1 and Figure 2, which has a first trapezoidal waveguide region 201 and a first rectangular waveguide region 202 connected to the end of the first trapezoidal waveguide region 201 with a larger width. The first waveguide portion 200 has a first trapezoidal waveguide region 201 and a first rectangular waveguide region 202 connected to the end of the first trapezoidal waveguide region 201 with a larger width; wherein the thickness of the first waveguide portion 200 is 60nm-100nm, the width of the end of the first trapezoidal waveguide region 201 with a smaller width is 180nm-200nm, the width of the end of the first trapezoidal waveguide region 201 with a larger width is 500nm-1μm, and the length of the first trapezoidal waveguide region 201 along the transmission direction of the composite light is 100μm-1000μm. The end of the first trapezoidal waveguide region 201 with a smaller width serves as the input end of the first waveguide portion 200, and the end with a larger width serves as the output end of the first waveguide portion 200. When the first waveguide portion 200 has the aforementioned dimensions, better coupling efficiency with the optical fiber 400 can be obtained.

[0050] Optionally, the thickness of the first waveguide portion 200 is 70 nm, the width of the smaller end of the first trapezoidal waveguide region 201 is 180 nm, the width of the larger end of the first trapezoidal waveguide region 201 is 800 nm, and the length of the first trapezoidal waveguide region 201 along the transmission direction of the composite light is 250 μm. When the first waveguide portion 200 has the aforementioned dimensions, better coupling efficiency with the optical fiber 400 can be obtained.

[0051] In the case where the second waveguide portion 300 is in an inverted cone shape, please refer to Figure 1 and Figure 2 The second waveguide portion 300 has a second trapezoidal waveguide region 301 and a second rectangular waveguide region 302 connected to the end of the second trapezoidal waveguide region 301 with a larger width; wherein the thickness of the second waveguide portion 300 is 150nm to 800nm, the width of the end with a smaller width of the second trapezoidal waveguide region 301 is 180nm to 200nm, the width of the end with a larger width of the second trapezoidal waveguide region 301 is 500nm to 1μm, and the length of the second trapezoidal waveguide region 301 along the transmission direction of the composite light is 100μm to 1000μm. When the second waveguide portion 300 has the aforementioned dimensions, better coupling efficiency with the first waveguide portion 200 and the waveguide included in the optical chip can be obtained at the same time.

[0052] Optionally, the thickness of the second waveguide portion 300 is 150 nm, the width of the smaller end of the second trapezoidal waveguide region 301 is 180 nm, the width of the larger end of the second trapezoidal waveguide region 301 is 800 nm, and the length of the second trapezoidal waveguide region 301 along the transmission direction of the composite light is 300 nm. When the second waveguide portion 300 has the aforementioned dimensions, better coupling efficiency with the optical chip can be obtained.

[0053] Specifically, please refer to Figure 1 , Figure 2 and Figure 3 , the end of the first rectangular waveguide area 202 away from the first trapezoidal waveguide area 201 serves as the output end of the first waveguide portion 200, and the side of the second rectangular waveguide area 302 away from the bottom side of the second trapezoidal waveguide area 301 serves as the output end of the second waveguide portion 300. Along the direction parallel to the surface of the substrate 100 and perpendicular to the transmission direction of the composite light, the two oppositely arranged side edges of the first trapezoidal waveguide area 201 are respectively parallel to the two oppositely arranged side edges of the second trapezoidal waveguide area 301. Along the transmission direction of the composite light, the thickness of each part of the first waveguide portion 200 and / or the second waveguide portion 300 is the same. The length of the end of the first rectangular waveguide area 202 connected to the first trapezoidal waveguide area 201 is equal to the length of the end of the second rectangular waveguide area 302 connected to the second trapezoidal waveguide area 301. The distance between the end of the first rectangular waveguide region 202 connected to the first trapezoidal waveguide region 201 and the end of the second rectangular waveguide region 302 connected to the second trapezoidal waveguide region 301 is 50 μm to 1000 μm. Along the transmission direction of the composite light, the distance between the end of the first trapezoidal waveguide region 201 away from the first rectangular waveguide region 202 and the end of the second trapezoidal waveguide region 301 away from the second rectangular waveguide region 302 is 50 μm to 200 μm. The distance between the end of the first rectangular waveguide region 202 connected to the first trapezoidal waveguide region 201 and the end of the second rectangular waveguide region 302 connected to the second trapezoidal waveguide region 301 is A; along the transmission direction of the composite light, the distance between the end of the first rectangular waveguide region 202 away from the first trapezoidal waveguide region 201 and the end of the second rectangular waveguide region 302 away from the second trapezoidal waveguide region 301 is B, and B is equal to A.

[0054] Optionally, the distance between the smaller end of the first trapezoidal waveguide region 201 and the smaller end of the second trapezoidal waveguide region 301 is 100 μm, and the distance between the larger end of the first trapezoidal waveguide region 201 and the larger end of the second trapezoidal waveguide region 301 is 150 μm.

[0055] In a specific application process, in order to achieve better coupling efficiency between the first waveguide portion 200 and the second waveguide portion 300, the coupling waveguide structure further includes at least one layer of a third waveguide portion between the first waveguide portion 200 and the second waveguide portion 300, and the thickness of the first waveguide portion 200, the third waveguide portion and the second waveguide portion 300 gradually increases along the direction from the first waveguide portion 200 to the second waveguide portion 300.

[0056] Considering the light leakage at the edge of the coupled waveguide structure, please refer to Figure 4A first cladding 501 is also provided between the coupling waveguide structure and the substrate 100, and a second cladding 502 is also provided on the upper surface of the coupling waveguide structure. The refractive index difference between the cladding structure and the coupling waveguide structure can effectively control the composite light within the coupling waveguide structure. In addition, the embodiment of the present application does not impose any specific restrictions on the material and thickness of the first cladding 501 and the second cladding 502, as long as the light leakage problem at the edge of the coupling waveguide structure can be effectively controlled. Optionally, the materials of the first cladding 501 and the second cladding 502 are both silicon dioxide, and the thickness of the first cladding 501 is 3 μm.

[0057] According to the above scheme, please refer to Figure 5 , Figure 5 This is a diagram of the electric field distribution at different positions of the embodiment of the present application. It can be seen that as the distance from the coupling section of the optical fiber 400, that is, the end with the smaller width of the first trapezoidal waveguide region 201, increases, the light energy in the coupled waveguide structure is gradually transmitted to the waveguide included in the optical chip coupled to the second waveguide portion 300.

[0058] In one embodiment, when the width of the smaller end of the first trapezoidal waveguide region 201 is 180 nm, please refer to Figure 6 Within the thickness range of the first waveguide portion 200 provided in the embodiment of the present application, the end face coupler has a higher overlap integral with the optical fiber 400 and the composite light, that is, a higher coupling efficiency is obtained.

[0059] In a second aspect, an embodiment of the present application provides an optical chip, which includes the end face coupler provided by the first aspect and various implementations thereof.

[0060] The beneficial effects of the second aspect and its various implementations in the embodiments of the present application can be analyzed by referring to the beneficial effects of the first aspect and its various implementations, and will not be repeated here.

[0061] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0062] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An end coupler, characterized in that: include: substrate; A coupled waveguide structure is arranged on the substrate; the coupled waveguide structure at least comprises a first waveguide portion and a second waveguide portion stacked along the thickness direction of the substrate; the input end of the first waveguide portion is the input end of the end face coupler, and the output end of the second waveguide portion is the output end of the end face coupler; the output end of the first waveguide portion is aligned with the output end of the second waveguide portion; The thickness of the first waveguide portion is smaller than that of the second waveguide portion; the input end of the first waveguide portion is coupled to an optical fiber, and the optical fiber is used to transmit composite light, wherein the composite light includes at least two optical signals of different wavelength bands, and the difference between the wavelengths of each two optical signals of different wavelength bands in the composite light is greater than or equal to 20 nm.

2. The end coupler according to claim 1, characterized in that: The composite light wavelength range is 630nm-860nm; the material of the coupled waveguide structure includes silicon nitride.

3. The end coupler according to claim 1 or claim 2, characterized in that: The cross-sectional shape of the first waveguide portion is a cone, an inverted cone, a scissors shape or a cantilever shape; and / or, the cross-sectional shape of the second waveguide portion is a cone, an inverted cone, a scissors shape or a cantilever shape; And / or, the cross-sectional shapes of the first waveguide portion and the second waveguide portion are the same, and the cross-sectional area of ​​the second waveguide portion is smaller than the cross-sectional area of ​​the first waveguide portion.

4. The end coupler according to claim 3, characterized in that: In the case where the first waveguide portion is an inverted tapered waveguide portion and the wavelength range of the composite light is 630nm to 860nm, the first waveguide portion has a first trapezoidal waveguide region and a first rectangular waveguide region connected to an end of the first trapezoidal waveguide region with a larger width; wherein the thickness of the first waveguide portion is 60nm to 100nm, the width of the end of the first trapezoidal waveguide region with a smaller width is 180nm to 200nm, the width of the end of the first trapezoidal waveguide region with a larger width is 500nm to 1μm, and the length of the first trapezoidal waveguide region along the transmission direction of the composite light is 100μm to 1000μm; And / or, when the second waveguide portion is an inverted tapered waveguide portion and the wavelength range of the composite light is 630nm to 860nm, the second waveguide portion has a second trapezoidal waveguide region, and a second rectangular waveguide region connected to the end of the second trapezoidal waveguide region with a larger width; wherein the thickness of the second waveguide portion is 150nm to 800nm, the width of the end with a smaller width of the second trapezoidal waveguide region is 180nm to 200nm, the width of the end with a larger width of the second trapezoidal waveguide region is 500nm to 1μm, and the length of the second trapezoidal waveguide region along the transmission direction of the composite light is 100μm to 1000μm.

5. The end coupler according to claim 4, characterized in that: Along a direction parallel to the surface of the substrate and perpendicular to the transmission direction of the composite light, two oppositely disposed side edges of the first trapezoidal waveguide region are respectively parallel to two oppositely disposed side edges of the second trapezoidal waveguide region.

6. The end coupler according to claim 1, characterized in that: Along the transmission direction of the composite light, thicknesses of various parts of the first waveguide portion and / or the second waveguide portion are the same.

7. The end coupler according to claim 4, characterized in that: The length of one end of the first rectangular waveguide region connected to the first trapezoidal waveguide region is equal to the length of one end of the second rectangular waveguide region connected to the second trapezoidal waveguide region; and / or, a distance between one end of the first rectangular waveguide region connected to the first trapezoidal waveguide region and one end of the second rectangular waveguide region connected to the second trapezoidal waveguide region is 50 μm to 1000 μm; And / or, along the transmission direction of the composite light, a distance between one end of the first trapezoidal waveguide region away from the first rectangular waveguide region and one end of the second trapezoidal waveguide region away from the second rectangular waveguide region is 50 μm to 200 μm.

8. The end coupler according to claim 4, characterized in that: The distance between one end of the first rectangular waveguide region connected to the first trapezoidal waveguide region and one end of the second rectangular waveguide region connected to the second trapezoidal waveguide region is A; along the transmission direction of the composite light, the distance between one end of the first rectangular waveguide region away from the first trapezoidal waveguide region and one end of the second rectangular waveguide region away from the second trapezoidal waveguide region is B, and B is equal to A.

9. The end coupler according to claim 1, characterized in that: The coupled waveguide structure further includes at least one layer of a third waveguide portion, and along a direction from the first waveguide portion to the second waveguide portion, thicknesses of the first waveguide portion, the third waveguide portion and the second waveguide portion gradually increase.

10. An optical chip, characterized in that: It comprises the end face coupler as claimed in any one of claims 1 to 9.

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