Chip for end-face coupling, method of manufacture and optical device

Abstract

The application particularly relates to a chip for end face coupling, a preparation method and an optical device, the chip comprising: a substrate, a coupling area arranged on the substrate and extending inward from the edge of the substrate, a beam combining area butting against the coupling area, and an adiabatic area butting against the beam combining area; the coupling area comprises symmetrically arranged narrow-to-wide coupling waveguides; the beam combining area comprises a first beam combining waveguide extending inward from the end of the coupling waveguide, and a second beam combining waveguide arranged at the symmetry center of the first beam combining waveguide; and the adiabatic area comprises a transition waveguide extending inward from the end of the second beam combining waveguide, and an adiabatic waveguide arranged at the transition waveguide. The application realizes efficient conversion of a large mode spot of a single-mode optical fiber by simultaneously improving the power overlap efficiency and the power transmission efficiency of the single-mode optical fiber and the chip for end face coupling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mode spot converter, and particularly relates to a chip for end face coupling, a preparation method and an optical device. BACKGROUND

[0002] With the rapid development of optical fiber communication, optical communication technology has been widely applied in every corner of the world. In the coupling process of optical fiber and chip, horizontal coupling and vertical coupling are included. When the horizontal coupling technology route is adopted, single mode optical fiber often faces the problem of excessive coupling loss due to the difference in mode spot size between the single mode optical fiber and the chip. In the prior art, the structure of the waveguide of the chip is usually designed, so that the mode spot of the single mode optical fiber can match the mode spot of the chip after conversion, so as to achieve the purpose of reducing the coupling loss. In recent years, with the development of integrated photonics technology and micro-nano processing technology, researchers have carried out a lot of research on the improvement of the coupling efficiency of integrated end face coupling chip. By introducing new device structures, such as cantilever quantity, heterogeneous integrated cladding, more than three layer waveguide lithography structure, etc., higher efficiency and more compact end face coupling chip coupling efficiency can be achieved.

[0003] Although the integrated end face coupling chip technology in the prior art has made significant progress, there are still many challenges in practical application. One of the main challenges is the conflict between high mode coupling efficiency and simple manufacturing process. Although the end face coupling chip provided in the prior art has the advantages of high coupling efficiency, large bandwidth, easy packaging and the like, the mode field diameter of the single waveguide end face coupling chip is small, and many new structures have complex preparation processes, which require multiple etching, narrow waveguide, cantilever beam structure, and some end face coupling chips also need heterogeneous integration, which further aggravates the complexity of the process, resulting in a cumbersome production process of the end face coupling chip, high cost investment, and difficulty in realizing large-scale manufacturing and application. SUMMARY

[0004] The present application provides an end face coupling chip, which at least has the advantages of high coupling efficiency, simple structure, high reliability, low preparation cost and the like.

[0005] First aspect

[0006] The present application provides an end face coupling chip, which at least has the advantages of high coupling efficiency, simple structure, high reliability, low preparation cost and the like.

[0007] The substrate, the coupling area arranged on the substrate and extending inward from the edge of the substrate, the beam combining area butting against the coupling area, and the adiabatic area butting against the beam combining area are provided.

[0008] The coupling area includes symmetrically arranged coupling waveguides from narrow to wide.

[0009] The beam combining area includes a first beam combining waveguide extending inward from the end of the coupling waveguide, and a second beam combining waveguide arranged at the symmetry center of the first beam combining waveguide.

[0010] The adiabatic area includes a transition waveguide extending inward from the end of the second beam combining waveguide, and an adiabatic waveguide connected to the end of the transition waveguide.

[0011] Specifically, one of the main ideas of the present application is to use the inverted cone-shaped coupling waveguide with symmetrical design on both sides in the coupling area to improve the power overlap efficiency and power transmission efficiency of the single-mode optical fiber and the coupling waveguide, and at the same time, to further improve the power transmission efficiency of light through the structural design of the first beam combining waveguide and the second beam combining waveguide in the beam combining area, so as to achieve the purpose of efficient coupling of the single-mode optical fiber and the end-coupling chip.

[0012] Optionally, the present application provides an end-coupling chip, which comprises:

[0013] The coupling waveguide arranged symmetrically has an outward opening horn shape, and the included angle between the coupling waveguide on either side and the light transmission direction ranges from 0° to 50°.

[0014] Further, the width of the coupling waveguide changes linearly or nonlinearly.

[0015] The nonlinear change includes parabolic, exponential, and logarithmic types.

[0016] Specifically, the nonlinear change of the width of the coupling waveguide can effectively shorten the coupling length of the coupling waveguide, and reduce the volume of the end-coupling chip.

[0017] Optionally, the width of the first beam combining waveguide changes from narrow to wide, and the width of the second beam combining waveguide changes from narrow to wide.

[0018] Specifically, another main technical idea of the present application is to linearly or nonlinearly design the width of the first beam combining waveguide and the second beam combining waveguide based on the continuous design of the coupling waveguide and the first beam combining waveguide in the coupling area and the design of the second beam combining waveguide at the symmetry center of the first beam combining waveguide, so as to optimize the layout of the entire end-coupling chip and make the overall volume smaller.

[0019] Further, the present application provides an end-coupling chip, which comprises:

[0020] The initial end of the coupling waveguide is preset to have a first width, and the initial end of the second beam combining waveguide is preset to have a second width.

[0021] The first width and the second width are adjusted based on the ratio of the mode spot diameter of the single-mode fiber to the mode spot diameter of the adiabatic waveguide.

[0022] Specifically, one of the technical ideas of the present application is to adjust the sizes of the first width and the second width to adapt to different scenarios of the ratio of the mode spot diameter of the single-mode fiber to the mode spot diameter of the adiabatic waveguide. At the same time, the size of the first width is adjusted to adapt to different power overlap efficiencies, and the size of the second width is adjusted to adapt to different transmission process efficiencies.

[0023] Further, the adiabatic waveguide includes a first waveguide and a second waveguide, and an end of the first waveguide is a start of the second waveguide.

[0024] The width of the first waveguide changes from narrow to wide, and the width of the second waveguide does not change.

[0025] Specifically, the first waveguide is used to further improve the transmission process efficiency, and the second waveguide is used to complete the transmission of the mode spot conversion light.

[0026] Further, the transition waveguide includes a third waveguide, a fourth waveguide, and a fifth waveguide.

[0027] An end of the second beam combining waveguide is a start of the third waveguide, an end of the third waveguide is a start of the fourth waveguide, and an end of the fourth waveguide is a start of the fifth waveguide.

[0028] Further, the end face coupling chip includes a three-layer structure.

[0029] The substrate is arranged in the first structure layer.

[0030] The coupling region, the beam combining region, and the transition waveguide of the adiabatic region of the end face coupling chip are arranged in the second structure layer.

[0031] The adiabatic waveguide is arranged in the third structure layer.

[0032] Specifically, one of the technical ideas of the present application is to use a three-layer structure design to make the structure layout of the end face coupling chip provided by the present application simple and reliable, easy to process and produce.

[0033] Second aspect

[0034] The present application provides a preparation method of an end face coupling chip, for preparing the end face coupling chip provided by any possible embodiment of the first aspect, comprising:

[0035] Processing the coupling region, the beam combining region, and the transition waveguide of the adiabatic region on the substrate.

[0036] On the basis of the transition waveguide, an adiabatic waveguide is processed.

[0037] Third aspect

[0038] The application provides an optical device for end face coupling, comprising the chip for end face coupling provided in any possible embodiment of the first aspect, comprising:

[0039] A single-mode optical fiber, the coupling waveguide is butted against the single-mode optical fiber.

[0040] In conclusion, the application provides a chip for end face coupling, a preparation method and an optical device, and the application has at least the following advantages:

[0041] 1. One of the main ideas of the application is to use the symmetrically designed coupling waveguides on both sides in the coupling area and the hierarchical design of the first beam combining waveguide and the second beam combining waveguide in the beam combining area, to improve the power overlap efficiency of light between the single-mode optical fiber and the coupling waveguide and the power transmission efficiency of light in the chip for end face coupling, and to achieve the purpose of efficient coupling between the single-mode optical fiber and the chip for end face coupling.

[0042] 2. The application also uses the multiplexing of the first beam combining waveguide and the coupling waveguide, in combination with the structural layout of the second beam combining waveguide arranged at the center, to improve the effective utilization of the integrated plane of the substrate, to realize the reduction of the volume of the chip for end face coupling provided by the application, and to achieve the purpose of reducing the chip volume.

[0043] 3. The application uses the design of the double-layer waveguide structure to reduce the manufacturing difficulty of the chip for end face coupling provided by the application, so that the chip for end face coupling provided by the application can be mass-produced, and the production and application cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0044] The application will be described in further detail below with reference to the drawings and preferred embodiments, but those skilled in the art will appreciate that the drawings are only drawn for the purpose of explaining the preferred embodiments and therefore should not be regarded as limiting the scope of the application. In addition, unless specifically indicated, the drawings only schematically show the composition or structure of the described objects and can include exaggerated displays, and the drawings are not necessarily drawn to scale.

[0045] Figure 1 A perspective view of a chip for end face coupling provided by an embodiment of the application;

[0046] Figure 2 A top view of a chip for end face coupling provided by an embodiment of the application;

[0047] Figure 3A flowchart of a preparation method of an end-face coupling chip is provided in an embodiment of the present application.

[0048] Figure 4 A theoretical light field propagation diagram of a second structure layer of an end-face coupling chip is provided in an embodiment of the present application.

[0049] Figure 5 A theoretical light field propagation diagram of a third structure layer of an end-face coupling chip is provided in an embodiment of the present application.

[0050] Figure 6 A theoretical loss spectrum diagram of an end-face coupling chip is provided in an embodiment of the present application.

[0051] 1, substrate; 2, coupling region; 3, beam combining region; 4, adiabatic region; 5, single-mode optical fiber; 21, coupling waveguide; 31, first beam combining waveguide; 32, second beam combining waveguide; 41, adiabatic waveguide; 42, transition waveguide; 41a, first waveguide; 41b, second waveguide; 42a, third waveguide; 42b, fourth waveguide; 42c, fifth waveguide; 42d, transition block. DETAILED DESCRIPTION

[0052] The present application will be described in detail below with reference to the accompanying drawings and embodiments. Figures 1 to 6 The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0053] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0054] The main technical concept of the present application is to use the coupling waveguides symmetrically designed on both sides in the coupling region and the cascade design of the first beam combining waveguide and the second beam combining waveguide in the beam combining region, to simultaneously improve the power overlap efficiency of light between the single-mode optical fiber and the coupling waveguide and the power transmission efficiency of light in the end-face coupling chip, and to further achieve the purpose of efficient coupling between the single-mode optical fiber and the end-face coupling chip. At the same time, the structure layout and structure style of the end-face coupling chip are also designed in the present application, so that the chip regions are combined compactly and reliably, and the volume of the chip is smaller and the processing technology is simpler.

[0055] Further, please refer to Figure 1 Fig. 1 shows a perspective view of an end-face coupling chip provided in an embodiment of the present application. Embodiment 1

[0056] The end face coupling chip provided by the application comprises a substrate, a coupling area arranged on the substrate and extending inward from the edge of the substrate, a beam combining area butting against the coupling area, and an adiabatic area butting against the beam combining area. The coupling area comprises symmetrically arranged coupling waveguides from narrow to wide, the beam combining area comprises a first beam combining waveguide extending inward from the end of the coupling waveguide and a second beam combining waveguide arranged at the symmetry center of the first beam combining waveguide, and the adiabatic area comprises a transition waveguide extending inward from the end of the second beam combining waveguide and an adiabatic waveguide connected to the end of the transition waveguide. Therefore, the working principle of the application is that the coupling area is used for coupling light transmitted from a single-mode optical fiber and transmitting and converting the light through the coupling waveguide; the beam combining area receives the light of the coupling waveguide through the first beam combining waveguide, combines the light into the second beam combining waveguide, and further transmits and converts the light into the adiabatic area; the adiabatic transition waveguide transmits and converts the light while transitioning the light to the adiabatic waveguide, and the adiabatic waveguide is used for further transmitting the light. Thus, the end face coupling chip provided by the application completes the mode spot conversion of the light of the single-mode optical fiber, so that the light can be transmitted on the chip. Therefore, the working principle of the application is that the signal light of the single-mode optical fiber is coupled through the coupling area, then transmitted to the adiabatic area after beam combining through the beam combining area, and finally the signal light after the mode spot conversion is transmitted.

[0057] It is worth explaining that the beginning end of the first beam combining waveguide is the end of the coupling waveguide, that is, the first beam combining waveguide is a continuation of the coupling waveguide, and the two belong to the coupling area and the adiabatic area respectively but are integrally formed. The following description about the connection relationship between the beginning end and the end can be referred to based on this, and all are integrally formed.

[0058] Further, the center line of the light transmitted from the single-mode optical fiber is the symmetry center line of the coupling area and the first beam combining waveguide. Embodiment 2

[0059] Based on embodiment 1, the adiabatic waveguide comprises a first waveguide and a second waveguide, the end of the first waveguide is the beginning end of the second waveguide; the transition waveguide comprises a third waveguide, a fourth waveguide and a fifth waveguide, the end of the third waveguide is the beginning end of the fourth waveguide, and the end of the fourth waveguide is the beginning end of the fifth waveguide.

[0060] Optionally, the end of the fifth waveguide is aligned with another edge of the substrate.

[0061] Optionally, the end of the fifth waveguide is the beginning end of a transition block, and the end of the transition block is aligned with another edge of the substrate.

[0062] Optionally, the end face coupling chip provided by embodiment 1 comprises a three-layer structure; the substrate is arranged on a first structure layer; the coupling area, the beam combining area and the transition waveguide are arranged on a second structure layer; and the adiabatic waveguide is arranged on a third structure layer.

[0063] Further, the second structure layer and the third structure layer are made of the same material, including silicon-based material, group III-V material and lithium niobate.

[0064] Further, please refer to Figure 2 Fig. 1 is a top view of a chip for end-coupling provided by an embodiment of the present application. Embodiment 3

[0065] On the basis of embodiment 1 or embodiment 2, the coupling waveguide is in the shape of an outward opening horn, and the included angle between any side of the coupling waveguide and the light transmission direction ranges from 0° to 50°. Embodiment 4

[0066] On the basis of embodiment 2 or embodiment 3, the width of the first beam-combining waveguide changes from narrow to wide, the width of the second beam-combining waveguide changes from narrow to wide, the width of the first waveguide changes from narrow to wide, the width of the second waveguide does not change, the width of the third waveguide changes from narrow to wide, the width of the fourth waveguide changes from narrow to wide, and the width of the fifth waveguide changes from narrow to wide. The width changes of the first beam-combining waveguide, the second beam-combining waveguide, the first waveguide, the third waveguide, the fourth waveguide and the fifth waveguide are linear or nonlinear, and the nonlinear includes parabolic, exponential or logarithmic.

[0067] Optionally, the included angle between any side of the second beam-combining waveguide and the light transmission direction ranges from 0° to 25°, and the narrower the tip of the second beam-combining waveguide, the higher the beam-combining efficiency of the light beam from the first beam-combining waveguide to the second beam-combining waveguide.

[0068] Optionally, the width changes of the coupling waveguide, the first beam-combining waveguide, the second beam-combining waveguide, the first waveguide, the third waveguide, the fourth waveguide and the fifth waveguide are all nonlinear.

[0069] Optionally, the width changes of the coupling waveguide, the first beam-combining waveguide, the second beam-combining waveguide, the first waveguide, the third waveguide, the fourth waveguide and the fifth waveguide include any combination of linear and nonlinear.

[0070] Optionally, the beginning end and the ending end of the first waveguide are respectively aligned with the beginning end and the ending end of the fourth waveguide in space.

[0071] Further, the width of the first waveguide is narrower than that of the fourth waveguide.

[0072] Optionally, the ending end of the second waveguide is aligned with the edge of the substrate.

[0073] Optionally, the three sides of the transition block are respectively aligned with the edges of the three sides of the substrate.

[0074] Optionally, the third waveguide, the fourth waveguide and the fifth waveguide are unfolded successively.

[0075] Optionally, the coupling waveguide, the first beam-combining waveguide, the second beam-combining waveguide, the transition waveguide and the adiabatic waveguide each comprises an oxide protective layer.

[0076] Optionally, the working waveband of the present application is C waveband, i.e. the radio waveband with a frequency range between 4.0 and 8.0 GHz.

[0077] Optionally, the working mode of the present application comprises transverse electric mode (TE) or transverse magnetic mode (TM). Embodiment 5

[0078] On the basis of any one of Embodiments 1 to 4, the present application provides an optical device, which comprises a chip for end-face coupling and a single-mode optical fiber butting against the initial end of the coupling waveguide of the chip.

[0079] Further, please refer to Figure 3 Fig. 1 shows a flowchart of a preparation method of a chip for end-face coupling according to an embodiment of the present application. Embodiment 6

[0080] The present application provides a preparation method of a chip for end-face coupling, which is used for the preparation of the chip for end-face coupling provided in any one of Embodiments 1 to 5, and comprises: processing a transition waveguide of the coupling region, the beam-combining region and the adiabatic region on a substrate; and processing an adiabatic waveguide on the basis of the transition waveguide.

[0081] Optionally, the preparation method adopted in Embodiment 6 comprises one or more of the following: laser direct writing, electron beam exposure combined with etching, photolithography combined with etching, and focused ion beam.

[0082] Optionally, the etching angle of the second structural layer and the third structural layer is 70°.

[0083] Further, please refer to Figure 4 Fig. 3 shows a theoretical light field propagation diagram of the second structural layer of a chip for end-face coupling according to an embodiment of the present application.

[0084] Specifically, the present application provides a chip for end-face coupling prepared by a thin film of niobium oxide, Figure 4 which is a theoretical light field propagation diagram of the second structural layer, and the process of light transmission from the single-mode optical fiber to the second structural layer has high coupling efficiency.

[0085] Further, please refer to Figure 5 Fig. 4 shows a theoretical light field propagation diagram of the third structural layer of a chip for end-face coupling according to an embodiment of the present application, and the process of light transition from the second structural layer to the third structural layer has high coupling efficiency.

[0086] Specifically, the application provides a chip for end face coupling prepared from a thin film niobate material, Figure 5 is a theoretical light field propagation diagram of the lower layer thereof.

[0087] Further, please refer to Figure 6 is a theoretical loss spectrum diagram of the chip for end face coupling provided by the embodiment of the application.

[0088] Specifically, the application provides a chip for end face coupling prepared from a thin film niobate material, Figure 6 is a coupling efficiency diagram of a single mode optical fiber with a mode spot diameter of 3.2 μm. In a wavelength range of 1530 nm to 1565 nm, the coupling efficiency is greater than 0.51 dB, wherein the coupling efficiency is 0.505 dB at 1550 nm. Based on the data structure, the chip for end face coupling, the optical device and the preparation method provided by the application can effectively provide the end face coupling efficiency, and can also reduce the device volume and the process manufacturing difficulty.

[0089] The application is described in detail above, the principle and the implementation mode of the application are described by using specific examples, and the above embodiment is only used for helping to understand the application and the core idea. It should be pointed out that, for ordinary skilled in the art, without departing from the principle of the application, the application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. A chip for end face coupling, characterized in that: include: A substrate, a coupling region disposed on the substrate and extending inward from an edge of the substrate, a beam combining region docked to the coupling region, and an insulation region docked to the beam combining region; The coupling region includes symmetrically arranged coupling waveguides from narrow to wide; The beam combining region includes a first beam combining waveguide extending inward from an end of the coupling waveguide, and a second beam combining waveguide arranged at a symmetric center of the first beam combining waveguide; The adiabatic region includes a transition waveguide extending inward from the end of the second beam-combining waveguide and an adiabatic waveguide connected to the end of the transition waveguide.

2. The end-face coupling chip according to claim 1, wherein: include: The symmetrically arranged coupling waveguides are in an outward-opening trumpet shape, and the angle between the coupling waveguides on either side and the light transmission direction ranges from 0° to 50°.

3. The end-face coupling chip according to claim 2, wherein: The width of the coupling waveguide changes linearly or nonlinearly; The nonlinearity includes parabolic, exponential and logarithmic types.

4. The end-face coupling chip according to claim 1, wherein: The width of the first beam-combining waveguide changes from narrow to wide, and the width of the second beam-combining waveguide changes from narrow to wide.

5. The end-face coupling chip according to claim 4, characterized in that: include: The starting end of the coupling waveguide is preset to a first width, and the starting end of the second beam combining waveguide is preset to a second width; The first width and the second width are adjusted based on a ratio of a mode spot diameter of the single-mode optical fiber to a mode spot diameter of the adiabatic waveguide.

6. The end-face coupling chip according to claim 1, wherein: The adiabatic waveguide includes a first waveguide and a second waveguide, and the end of the first waveguide is the starting end of the second waveguide; The width of the first waveguide changes from narrow to wide, and the width of the second waveguide does not change.

7. The end-face coupling chip according to claim 6, characterized in that: The transition waveguide includes a third waveguide, a fourth waveguide, and a fifth waveguide; The end of the second beam-combining waveguide is the starting end of the third waveguide, the end of the third waveguide is the starting end of the fourth waveguide, and the end of the fourth waveguide is the starting end of the fifth waveguide.

8. The end-face coupling chip according to claim 1, wherein: The end face coupling chip comprises a three-layer structure; The substrate is arranged on the first structural layer; The coupling region, the beam combining region and the transition waveguide are arranged in the second structural layer; The thermal insulation waveguide is arranged in the third structural layer.

9. A method for preparing an end-face coupling chip, for preparing an end-face coupling chip according to any one of claims 1 to 8, characterized in that: include: Processing the transition waveguides in the coupling region, the beam combining region and the adiabatic region on the substrate; Based on the transition waveguide, an adiabatic waveguide is processed.

10. An optical device with an end-face coupling chip, comprising the end-face coupling chip according to any one of claims 1 to 8, characterized in that: include: Single-mode optical fiber, the coupling waveguide is connected to the single-mode optical fiber.

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