Optical coupler, optical chip, and optical communication device

Abstract

The application provides an optical coupler applied to the field of optical communication. The optical coupler comprises a buried layer, a support layer, a waveguide layer and an upper cladding layer. In the height direction, the support layer is between the buried layer and the waveguide layer. The waveguide layer is between the support layer and the upper cladding layer. In the width direction, the waveguide layer and the support layer are inside the upper cladding layer. The materials of the waveguide layer and the support layer are different. In the application, the support layer is inside the upper cladding layer. Therefore, the upper cladding layer is on both sides of the support layer. The energy of the optical signal can be dispersed on both sides of the support layer, so that the degree of uneven energy distribution near the center of the waveguide layer is reduced, and the coupling loss of the optical coupler is reduced.

Description

Technical Field

[0001] This application relates to the field of optical communication, and more particularly to optical couplers, optical chips and optical communication equipment. Background Technology

[0002] In the field of optical communication, different optical devices may support different mode sizes. For example, different optical devices include optical fibers and optical transceiver modules. Optical transceiver modules typically support mode sizes smaller than 1 micrometer. Standard single-mode optical fibers support mode sizes of approximately 10 micrometers. This significant difference in mode sizes leads to excessive losses in the direct coupling between the optical fiber and the optical transceiver module.

[0003] Therefore, optical coupling between different optical devices can be achieved by changing the mode size of the optical signal using an optical coupler. For example, Figure 1 This is a schematic diagram of the cross-section of an optical coupler along its width. (Example:) Figure 1 As shown, the optical coupler includes a buried layer 101, a waveguide layer 102, and an upper cladding layer 103. Figure 1 In this diagram, the Y-axis represents the width direction, and the X-axis represents the height direction. The Z-axis, perpendicular to both the X and Y axes, represents the transmission direction. The transmission direction includes a forward transmission direction and a reverse transmission direction. Along the forward transmission direction, the area of ​​the waveguide layer 102 continuously decreases, the area of ​​the upper cladding layer 103 continuously increases, and the area of ​​the buried layer 101 remains constant. The optical signal is transmitted along the transmission direction. For the reverse optical signal from the optical fiber, transmitted in the reverse transmission direction, the optical coupler is used to reduce the mode size of the reverse optical signal and transmit the reduced-mode reverse optical signal to the optical transceiver module. For the forward optical signal from the optical transceiver module, transmitted in the forward transmission direction, the optical coupler is used to amplify the mode size of the forward optical signal and transmit the amplified-mode forward optical signal to the optical fiber. During the optical coupling process, the center of the optical fiber is aligned with the center of the waveguide layer 102.

[0004] In practical applications, the refractive index of the upper cladding 103 is greater than that of the buried layer 101. Therefore, as the area of ​​the waveguide layer 102 decreases, the energy of the optical signal is mainly dispersed in the upper cladding 103. At this point, the energy of the optical signal in the buried layer 101 is much less than that in the upper cladding 103, resulting in greater losses in the optical coupler and fiber coupling. Summary of the Invention

[0005] This application provides an optical coupler, an optical chip, and an optical communication device. By adding a support layer, the degree of uneven energy distribution near the center of the waveguide layer can be reduced, thereby reducing the coupling loss of the optical coupler.

[0006] This application provides an optical coupler. The optical coupler includes a buried layer, a support layer, a waveguide layer, and an upper cladding layer. In the height direction, the support layer is located between the buried layer and the waveguide layer. The waveguide layer is located between the support layer and the upper cladding layer. In the width direction, the waveguide layer and the support layer are located inside the upper cladding layer. The waveguide layer and the support layer are made of different materials.

[0007] In this application, the support layer is located inside the upper cladding. Therefore, the upper cladding is present on both sides of the support layer. The energy of the optical signal can be dispersed on both sides of the support layer, thereby reducing the degree of uneven energy distribution near the center of the waveguide layer and reducing the coupling loss of the optical coupler.

[0008] In this application, the support layer is a waveguide structure, which can be a waveguide formed by etching and burying, a waveguide formed by deposition, or formed by epitaxy or other methods; this application is not limited to these methods. The support layer is used to support the waveguide but does not have the function of transmitting optical signals.

[0009] Since the shape of the support waveguide is the same as the gradient shape of the waveguide layer and it is located below the waveguide layer, the waveguide layer can be symmetrically filled by the upper cladding, thereby reducing the coupling loss of the optical coupler.

[0010] In one alternative embodiment of the first aspect of this application, the distance between the center of the waveguide layer and the center of the upper cladding layer in the width direction is less than 50 nanometers. Reducing the distance between the center of the waveguide layer and the center of the upper cladding layer can further reduce the degree of energy distribution unevenness near the center of the waveguide layer, thereby reducing coupling loss.

[0011] In one alternative embodiment of the first aspect of this application, the upper cladding is square or circular in the width direction. This square or circular upper cladding can further reduce coupling loss when the optical coupler is coupled to the optical fiber.

[0012] In one alternative embodiment of the first aspect of this application, an optical coupler is used to connect to an optical fiber. The diameter of the optical fiber is b micrometers. The width 'a' of the square is within the range b ± 0.5 micrometers, or the diameter 'a' of the circle is within the range b ± 0.5 micrometers. In this case, the difference between 'a' and 'b' is less than or equal to 0.5 micrometers. Wherein, when the diameter or width of the upper cladding is close to the diameter of the optical fiber, coupling loss can be further reduced.

[0013] In one optional embodiment of the first aspect of this application, the support layer includes a first end face and a second end face in the transmission direction. The area of ​​the first end face is larger than the area of ​​the second end face. The end face that outputs the forward optical signal transmitted along the forward transmission direction is the second end face. The end face that outputs the reverse optical signal transmitted along the reverse transmission direction is the first end face. When the area of ​​the second end face is smaller, the degree of uneven energy distribution near the center of the waveguide layer on the second end face can be effectively reduced, thereby reducing losses.

[0014] In one alternative embodiment of the first aspect of this application, the width of the support layer gradually decreases along the direction from the first end face to the second end face. While the width of the support layer gradually decreases, the cross-sectional area of ​​the upper cladding layer continuously increases in the width direction. Therefore, this application can further reduce the degree of energy distribution unevenness near the center of the waveguide layer and reduce coupling loss.

[0015] In one alternative embodiment of the first aspect of this application, the width of the second end face is less than 120 nanometers. The smaller the width of the second end face, the larger the cross-sectional area of ​​the upper cladding. A larger cross-sectional area of ​​the upper cladding results in a more uniform energy distribution near the center of the waveguide layer. This application limits the width of the second end face to less than 120 nanometers, which can reduce the degree of uneven energy distribution near the center of the waveguide layer, thereby reducing coupling loss.

[0016] In one alternative embodiment of the first aspect of this application, the upper cladding covers the second end face in the transmission direction. By covering the second end face, the cross-sectional area of ​​the upper cladding can be further increased, reducing the degree of energy distribution unevenness near the center of the waveguide layer and lowering coupling loss.

[0017] In one alternative embodiment of the first aspect of this application, the waveguide layer has a trapezoidal structure in the transmission direction. Specifically, the width of the waveguide layer gradually decreases along the positive transmission direction. When the waveguide layer comprises an upper waveguide layer and a lower waveguide layer, a trapezoidal structure means that the upper waveguide layer and / or the lower waveguide layer has a trapezoidal structure. In the positive transmission direction, the trapezoidal structure of the waveguide layer helps to disperse the forward optical signal within the upper cladding, reducing the degree of uneven energy distribution near the center of the waveguide layer, thereby reducing coupling loss.

[0018] In one alternative embodiment of the first aspect of this application, the waveguide layer comprises an upper waveguide layer and a lower waveguide layer. In the width direction, the width of the lower waveguide layer is greater than the width of the upper waveguide layer. The upper waveguide layer can also be referred to as a ridge waveguide. Dividing the waveguide layer into an upper and lower waveguide layer is beneficial in two ways: firstly, it helps reduce the transmission loss of the waveguide; secondly, it helps to expand the mode of the optical signal propagating in the positive transmission direction in the height direction, thereby reducing the degree of energy distribution unevenness near the center of the waveguide layer and thus reducing coupling loss.

[0019] In one alternative embodiment of the first aspect of this application, the upper waveguide layer comprises a first portion and a second portion. In the transmission direction, the first portion is a rectangular structure. The width of the first portion is between 400 nanometers and 2000 nanometers. The second portion is a trapezoidal structure. The minimum width of the trapezoidal structure is less than 120 nanometers.

[0020] In one alternative embodiment of the first aspect of this application, the lower waveguide layer includes a third end face and a fourth end face in the transmission direction. The lower waveguide layer has a trapezoidal structure. The width of the third end face is greater than the width of the fourth end face. The width of the fourth end face is less than 120 nanometers. The trapezoidal structure of the lower waveguide layer facilitates the dispersion of optical signals within the upper cladding, reducing the degree of energy unevenness near the center of the waveguide layer, thereby reducing coupling loss.

[0021] In one alternative embodiment of the first aspect of this application, in the transmission direction, the projection of the lower waveguide layer onto the buried layer coincides with the projection of the support layer onto the buried layer. Wherein, when the projections of the lower waveguide layer and the support layer onto the buried layer coincide, the widths of the lower waveguide layer and the support layer are the same. Having the same width between the lower waveguide layer and the support layer reduces the number of processing steps. Therefore, this application can reduce processing costs.

[0022] In one alternative embodiment of the first aspect of this application, the refractive index of the upper cladding material is greater than that of the support layer material. When the refractive index of the upper cladding material is greater than that of the support layer material, the energy of the forward optical signal is gradually dispersed in the upper cladding in the forward transmission direction, which can reduce the degree of uneven energy distribution near the center of the waveguide layer, thereby reducing coupling loss.

[0023] In one alternative embodiment of the first aspect of this application, the refractive index of the support layer material is less than that of the waveguide layer material. When the refractive index of the support layer material is less than that of the waveguide layer material, the energy of the reverse optical signal gradually concentrates on the waveguide layer in the opposite transmission direction, thereby reducing coupling loss.

[0024] In one alternative embodiment of the first aspect of this application, the material of the support layer is silicon dioxide.

[0025] In one alternative embodiment of the first aspect of this application, the material of the support layer and the material of the buried layer are the same. When the materials of the support layer and the buried layer are the same, the support layer and the buried layer can be obtained through an etching process. Therefore, this application can reduce the cost of the processing.

[0026] In one alternative embodiment of the first aspect of this application, the optical coupler further includes a substrate. In the height direction, a buried layer is located between the substrate and the support layer.

[0027] In an alternative embodiment of the first aspect of this application, the optical coupler further includes a body portion. The body portion further includes a body buried layer, a body waveguide layer, and a body upper cladding. The body waveguide layer is located between the body buried layer and the body upper cladding. The body waveguide layer and the waveguide layer have the same thickness.

[0028] A second aspect of this application provides an optical chip. The optical chip includes a first optical device and an optical coupler. The optical coupler is used to receive a reverse optical signal from a second optical device. The optical coupler is used to reduce the mode size of the reverse optical signal to obtain a reduced-mode reverse optical signal. The optical coupler is used to transmit the reduced-mode reverse optical signal to the first optical device. The first optical device is used to process the reduced-mode reverse optical signal.

[0029] In one alternative embodiment of the second aspect of this application, the first optical device is an optical transceiver module. The optical transceiver module is used to demodulate the reverse optical signal after reducing the mode size to obtain the input electrical signal.

[0030] In one alternative embodiment of the second aspect of this application, the first optical device is used to transmit a forward optical signal to an optical coupler. The optical coupler is used to amplify the mode of the forward optical signal to obtain a forward optical signal with amplified mode. The optical coupler is used to output the forward optical signal with amplified mode.

[0031] In one alternative embodiment of the second aspect of this application, the first optical device is an optical transceiver module. The optical transceiver module is used to obtain a second optical signal based on the output electrical signal.

[0032] A third aspect of this application provides an optical communication device. The optical communication device includes a processor and an optical chip. The optical chip is used to receive a reverse optical signal and obtain an input electrical signal based on the reverse optical signal. The processor is used to perform data processing on the input electrical signal.

[0033] In an alternative embodiment of the third aspect of this application, the processor is further configured to generate an output electrical signal. The optical chip is further configured to obtain a forward optical signal based on the output electrical signal and output the forward optical signal.

[0034] This application provides a fourth aspect of a method for fabricating an optical coupler. The method includes the following steps: providing a wafer. In the height direction, the wafer includes a substrate, a bottom layer, and a waveguide layer. The bottom layer is located between the waveguide layer and the substrate. Etching both sides of the wafer. The etching depth reaches the interior of the bottom layer, dividing the bottom layer into a support layer and a buried layer of different widths. In the height direction, the support layer is located between the buried layer and the waveguide layer. The width of the support layer is smaller than the width of the buried layer. The width of the etched waveguide layer is smaller than the width of the buried layer. Epitaxially growing an upper cladding layer on the etched wafer.

[0035] In one alternative embodiment of the fourth aspect of this application, the preparation method includes the following steps: etching the upper cladding layer such that the shape of the upper cladding layer is square or circular in the width direction.

[0036] In one alternative embodiment of the fourth aspect of this application, the etched wafer includes an upper waveguide layer and a lower waveguide layer with different widths. In the height direction, the lower waveguide layer is located between the support layer and the upper waveguide layer, and the width of the lower waveguide layer is greater than the width of the lower waveguide. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the cross-section of the optical coupler in the width direction;

[0038] Figure 2a This is a first three-dimensional structural schematic diagram of the optical coupler provided in this application;

[0039] Figure 2b This is a front view of the optical coupler provided in this application;

[0040] Figure 2c This is a first top view of the optical coupler provided in this application;

[0041] Figure 2d This is a schematic diagram of the first cross-section of the optical coupler provided in this application;

[0042] Figure 2e This is a second cross-sectional schematic diagram of the optical coupler provided in this application;

[0043] Figure 2f This is a third cross-sectional schematic diagram of the optical coupler provided in this application;

[0044] Figure 2g This is a schematic diagram of the fourth cross-section of the optical coupler provided in this application;

[0045] Figure 2h This is a schematic diagram of the fifth cross-section of the optical coupler provided in this application;

[0046] Figure 3 This is a schematic cross-sectional view of the circular upper waveguide layer provided in this application;

[0047] Figure 4a This is a second three-dimensional structural schematic diagram of the optical coupler provided in this application;

[0048] Figure 4b This is a second top view of the optical coupler provided in this application;

[0049] Figure 4c This is a schematic diagram of the sixth cross-section of the optical coupler provided in this application;

[0050] Figure 5 This is a schematic diagram of the structure of the optical coupler provided in this application;

[0051] Figure 6 This is a schematic diagram of the structure of the optical chip provided in this application;

[0052] Figure 7 This is a schematic diagram of the structure of the optical communication device provided in this application;

[0053] Figure 8 This is a schematic diagram of the structure of the optical communication system provided in this application;

[0054] Figure 9 This is a schematic flowchart of the fabrication method of the optical coupler provided in this application. Detailed Implementation

[0055] This application provides an optical coupler, an optical chip, and an optical communication device. By adding a support layer, the degree of uneven energy distribution near the center of the waveguide layer can be reduced, thereby reducing the coupling loss of the optical coupler. It should be understood that the terms "first," "second," "forward," and "reverse," etc., used in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or order. Furthermore, for the sake of brevity and clarity, reference numerals and / or letters are repeated in several figures of this application. This repetition does not indicate a strict limiting relationship between the various embodiments and / or configurations.

[0056] The optical coupler in this application can be applied to the field of optical communication. In optical communication, different optical devices may support different mode sizes. Therefore, an optical coupler can be used to change the mode size of the optical signal, achieving optical coupling between different optical devices. However, in... Figure 1 In the optical coupler shown, the energy distribution of the optical signal is uneven near the center of the waveguide layer 102, resulting in a large coupling loss of the optical coupler.

[0057] Therefore, this application provides an optical coupler. Figure 2a This is a first three-dimensional structural schematic diagram of the optical coupler provided in this application. Figure 2a In this diagram, the Y-axis represents the width direction, the X-axis represents the height direction, and the Z-axis represents the transmission direction. The transmission direction can be divided into the positive transmission direction and the negative transmission direction. Figure 2a The arrow on the Z-axis points in the positive direction of transmission. The arrow pointing in the opposite direction points in the negative direction of transmission. Optical signals transmitted in the positive direction are called forward optical signals. Optical signals transmitted in the negative direction are called reverse optical signals.

[0058] In this application, to facilitate the demonstration of the internal structure of the optical coupler, the upper cladding 204 is made transparent in the three-dimensional structural schematic diagram and top view of the optical coupler. For example... Figure 2a As shown, the optical coupler includes a buried layer 201, a support layer 202, a waveguide layer 203, and an upper cladding layer 204. Figure 2b This is a front view of the optical coupler provided in this application. Figure 2bAs shown, in the height direction, the support layer 202 is located between the buried layer 201 and the waveguide layer 203. The waveguide layer 203 is located between the support layer 202 and the upper cladding layer 204. The upper cladding layer 204 covers the waveguide layer 203 and the buried layer 201. To amplify the mode of the optical signal in the height direction, the waveguide layer 203 may include an upper waveguide layer and a lower waveguide layer. For example, in Figure 2b In the middle, waveguide layer 203 includes upper waveguide layer 2032 and lower waveguide layer 2031. Lower waveguide layer 2031 is located between support layer 202 and upper waveguide layer 2032.

[0059] The buried layer 201 can be made of silicon dioxide or quartz, etc. The support layer 202 can be made of oxides or fluorides, etc. Among them, oxides can be silicon dioxide, magnesium oxide, or aluminum oxide, etc. The waveguide layer 203 can be made of lithium niobate film, silicon, silicon nitride, or indium phosphide, etc. When the waveguide layer 203 includes an upper waveguide layer 2032 and a lower waveguide layer 2031, the materials of the upper waveguide layer 2032 and the lower waveguide layer 2031 can be the same or different. The upper cladding layer 204 can be made of silicon oxynitride, oxides, fluorides, etc. To reduce the cost in the processing, the buried layer 201 and the support layer 202 can be made of the same material. For example, the materials of the buried layer 201 and the support layer 202 can be silicon dioxide. In order to make the energy of the forward optical signal mainly dispersed in the upper cladding layer 204, the refractive index of the material of the upper cladding layer 204 can be greater than the refractive index of the materials of the support layer 202 and the buried layer 201. In order to concentrate the energy of the reverse light signal mainly in the waveguide layer 203, the refractive index of the waveguide layer 203 material can be greater than the refractive index of the upper cladding layer 204 material.

[0060] In this application, the optical coupler can be used to amplify the mode of a forward optical signal. The optical coupler can also be used to reduce the mode of a reverse optical signal. Therefore, the structure of the optical coupler can change along the transmission direction. For example, Figure 2c This is a first top view of the optical coupler provided in this application. Figure 2c As shown, the structure of the optical coupler is symmetrical along the centerline. Sections (or end faces) 1-5 divide the optical coupler into four parts. These four parts are: part 1 (between section 1 and section 2), part 2 (between section 2 and section 3), part 3 (between section 3 and section 4), and part 4 (between section 4 and section 5). Sections 1-5 are perpendicular to the transmission direction. Section 1 is the cutoff section of the optical coupler. Section 2 is the cutoff section between the lower waveguide layer 2031 and the support layer 202. Section 3 is the cutoff section of the upper waveguide layer 2032. Section 4 is the boundary section between the first and second parts of the upper waveguide layer 2032. Section 5 is the cutoff section of the support layer 202. Section 6 is the cutoff section of the optical coupler. The following section diagram illustrates the cutoff section... Figures 2d-2hThe four parts are described separately. It should be understood that the specific dimensions of the optical couplers provided in this application are only one or more examples and should not be used as a condition to limit the scope of protection of this application.

[0061] Figure 2d This is a schematic diagram of the first cross-section of the optical coupler provided in this application. Figure 2d This is a schematic diagram of the cross-section of section 1. (See diagram below.) Figure 2d As shown, the optical coupler includes a buried layer 201 and an upper cladding layer 204. The upper cladding layer 204 has a thickness of 6500 nanometers and a width of 6500 nanometers. The buried layer 201 has the same width as the upper cladding layer 204 and a thickness of 1700 nanometers.

[0062] Figure 2e This is a second cross-sectional schematic diagram of the optical coupler provided in this application. Figure 2e This is a schematic diagram of the cross-section of section 2. Figure 2e This can also be referred to as the left view of an optical coupler. For example... Figure 2e As shown, the optical coupler includes a buried layer 201, a support layer 202, a lower waveguide layer 2031, and an upper cladding layer 204. The lower waveguide layer 2031 has a thickness of 250 nanometers and a width of 100 nanometers. The support layer 202 has the same width as the lower waveguide layer 2031 and a thickness of 3000 nanometers. The distance between section 1 and section 2 is 500 micrometers. From section 1 to section 2, the thickness and width of the upper cladding layer 204 and the buried layer 201 in section 1 remain unchanged. The cross-sectional area of ​​the upper cladding layer 204 remains unchanged.

[0063] Figure 2f This is a third cross-sectional schematic diagram of the optical coupler provided in this application. Figure 2f This is a schematic diagram of the cross-section of section 3. (See diagram below.) Figure 2f The optical coupler includes a buried layer 201, a support layer 202, a lower waveguide layer 2031, an upper waveguide layer 2032, and an upper cladding layer 204. The upper waveguide layer 2032 has a thickness of 250 nanometers and a width of 100 nanometers. The lower waveguide layer 2031 has a width of 1200 nanometers. The support layer 202 has a width of 1200 nanometers. The distance between section 2 and section 3 is 100 micrometers. From section 2 to section 3, the thickness and width of the upper cladding layer 204 in section 2 remain unchanged. The cross-sectional area of ​​the upper cladding layer 204 gradually decreases. The thickness and width of the buried layer 201 remain unchanged. The thicknesses of the support layer 202 and the lower waveguide layer 2031 remain unchanged. The widths of the support layer 202 and the lower waveguide layer 2031 gradually increase.

[0064] Figure 2g This is a fourth cross-sectional schematic diagram of the optical coupler provided in this application. Figure 2gThis is a schematic diagram of the cross-section of section 4. (See diagram below.) Figure 2g The optical coupler includes a buried layer 201, a support layer 202, a lower waveguide layer 2031, an upper waveguide layer 2032, and an upper cladding layer 204. The upper waveguide layer 2032 has a width of 1200 nanometers. The lower waveguide layer 2031 has a width of 2600 nanometers. The support layer 202 has a width of 2600 nanometers. The distance between section 3 and section 4 is equal to 100 micrometers. From section 3 to section 4, the thickness and width of the upper cladding layer 204 in section 3 remain unchanged. The cross-sectional area of ​​the upper cladding layer 204 gradually decreases. The thickness and width of the buried layer 201 remain unchanged. The thickness of the support layer 202 and the lower waveguide layer 2031 remain unchanged. The width of the support layer 202 and the upper waveguide layer 2032 gradually increases. The thickness of the upper waveguide layer 2032 and the lower waveguide layer 2031 remains unchanged. The width of the lower waveguide layer 2031 gradually increases.

[0065] Figure 2h This is a fifth cross-sectional schematic diagram of the optical coupler provided in this application. Figure 2h This is a schematic diagram of section 5. Figure 2h This can also be referred to as the right view of an optical coupler. For example... Figure 2h As shown, the optical coupler includes a buried layer 201, a support layer 202, a lower waveguide layer 2031, an upper waveguide layer 2032, and an upper cladding layer 204. The width of the lower waveguide layer 2031 is 4000 nanometers. The width of the support layer 202 is 4000 nanometers. The distance between section 4 and section 5 is equal to 100 micrometers. The thickness and width of the upper cladding layer 204 in section 4 remain unchanged. The cross-sectional area of ​​the upper cladding layer 204 gradually decreases. The thickness and width of the buried layer 201 remain unchanged. The width of the upper waveguide layer 2032 remains unchanged. The thicknesses of the support layer 202 and the lower waveguide layer 2031 remain unchanged. The widths of the support layer 202 and the lower waveguide layer 2031 gradually increase.

[0066] In this application, according to Figures 2e to 2h It is known that the support layer 202 includes upper cladding layers on both sides. Therefore, the energy of the optical signal can be distributed on both sides of the support layer 202, thereby reducing the degree of uneven energy distribution near the center of the waveguide layer 203 and thus reducing the coupling loss of the optical coupler.

[0067] It should be understood that Figures 2a to 2h The optical couplers shown are merely one or more examples provided in this application. In practical applications, those skilled in the art can make adaptive modifications to the optical couplers according to their needs. Even after adaptive modifications, if the optical coupler includes a support layer, it should still fall within the protection scope of this application. Adaptive modifications include, but are not limited to, one or more of the following:

[0068] For example, in the aforementioned Figures 2d to 2hIn the middle, the upper cladding layer 204 is square in shape. In practical applications, the upper cladding layer 204 can also be rectangular or circular. For example, Figure 3 This is a schematic cross-sectional view of the circular upper waveguide layer provided in this application. Figure 3 As shown, the optical coupler includes a buried layer 201, a support layer 202, a lower waveguide layer 2031, an upper waveguide layer 2032, and an upper cladding layer 204. The upper cladding layer 204 is circular in shape.

[0069] For example, in the aforementioned Figures 2d to 2h In this design, the upper cladding 204 has a thickness and width of 6.5 micrometers. In practical applications, the side length 'a' of the upper cladding 204 can be within the range b ± 0.5 micrometers. 'b' is the mode field diameter of the optical fiber connected to the optical coupler. 'b' can be equal to 10.4 micrometers, 6.5 micrometers, or 3.2 micrometers. Similarly, when the upper cladding 204 is circular, the diameter 'a' of the circle can be within the range b ± 0.5 micrometers.

[0070] For example, in the aforementioned Figures 2d to 2h In the design, the center of the upper cladding layer 204 is the intersection of the diagonal lines connecting the two layers. Taking the lower left corner of the optical coupler as the origin, the coordinates (Y, X) of the center of the upper cladding layer 204 are (3.25, 4.95). The center of the waveguide layer 203 is the midpoint of the boundary line between the upper waveguide layer 2032 and the lower waveguide layer 2031. The coordinates (Y, X) of the center of the waveguide layer 203 (referred to as the center of waveguide layer 203) are (3.25, 4.95). At this point, the center of waveguide layer 203 coincides with the center of the upper cladding layer 204, meaning the distance between them is 0. In practical applications, the distance between the center of waveguide layer 203 and the center of the upper cladding layer 204 may not be 0. For example, the distance could be 40 nanometers. However, to minimize the uneven energy distribution near the center of waveguide layer 203, the distance between the center of waveguide layer 203 and the center of upper cladding layer 204 can be limited to less than 50 nanometers. It should be understood that the center of waveguide layer 203 can also be its centroid. When the thickness of upper waveguide layer 2032 is greater than the thickness of lower waveguide layer 2031, the center of waveguide layer 203 can also be the centroid of upper waveguide layer 2032. When the thickness of upper waveguide layer 2032 is less than the thickness of lower waveguide layer 2031, the center of waveguide layer 203 can also be the centroid of lower waveguide layer 2031.

[0071] For example, in the aforementioned Figures 2e to 2h In this configuration, the width of the support layer 202 is equal to the width of the lower waveguide layer 2031. The projection of the lower waveguide layer 2031 onto the buried layer 201 coincides with the projection of the support layer 202 onto the buried layer 201. In practical applications, the width of the support layer 202 can be greater than or less than the width of the lower waveguide layer 2031. (The above...) Figure 2c In this structure, the support layer 202 has a trapezoidal structure. The trapezoidal structure includes a first end face and a second end face. The first end face is on section 5, and the second end face is on section 2. The area of ​​the first end face is greater than the area of ​​the second end face. The width of the support layer 202 gradually decreases along the direction from the first end face to the second end face. In practical applications, the support layer 202 can be a rectangular structure. In this case, the areas of the first and second end faces of the support layer 202 are the same. The width of the support layer 202 remains unchanged along the direction from the first end face to the second end face.

[0072] For example, in the aforementioned Figure 2e In this design, the width of the second end face of the support layer 202 is equal to 100 nanometers. In practical applications, the width of the second end face can also be other values, such as 110 nanometers or 120 nanometers. However, the smaller the width of the second end face, the larger the cross-sectional area of ​​the upper cladding layer 204. When the cross-sectional area of ​​the upper cladding layer 204 is larger, the energy distribution near the center of the waveguide layer 203 is more uniform. Therefore, this application can limit the width of the second end face to less than 120 nanometers.

[0073] For example, in the aforementioned Figure 2c In the upper waveguide layer 2032, there are two parts. The first part is a rectangular structure located between section 5 and section 4. The width of the first part is between 400 nm and 2000 nm. The second part is a trapezoidal structure located between section 4 and section 3. The minimum width of the trapezoidal structure is less than 120 nm. The minimum width of the trapezoidal structure is located at section 3. The minimum width of the trapezoidal structure is equal to 100 nm. In practical applications, the upper waveguide layer 2032 can be a trapezoidal structure. Along the positive transmission direction, the width of the trapezoidal structure gradually decreases.

[0074] For example, in the aforementioned Figure 2e In the middle, the lower waveguide layer 2031 has a trapezoidal structure. The trapezoidal structure includes a third end face and a fourth end face. The third end face is on section 5. The fourth end face is on section 2. The width of the third end face is greater than the width of the fourth end face. The width of the fourth end face is less than 120 nanometers. In practical applications, the lower waveguide layer 2031 may include a third part and a fourth part. The third part is between section 4 and section 5. The third part has a rectangular structure. The fourth part is between section 4 and section 2. The fourth part has a trapezoidal structure.

[0075] For example, the optocoupler may also include a substrate. In the height direction, a buried layer 201 lies between the substrate and the support layer 202. The substrate material may be high-resistivity silicon, low-resistivity silicon, or quartz.

[0076] For example, an optical coupler may also include a body section. Figure 4a This is a second three-dimensional structural schematic diagram of the optical coupler provided in this application. Figure 4aAs shown, the optical coupler includes a protrusion (the part with the filled pattern in the figure) and a local part (the part without the filled pattern in the figure). The protrusion includes a substrate 400, a buried layer 201, a support layer 202, a waveguide layer 203, and an upper waveguide layer 204. A description of the protrusion can be found in the foregoing. Figures 2a to 2h and Figure 3 The body portion includes a substrate 400, a body buried layer 401, a body waveguide layer 403, and a body upper cladding layer 402. In the height direction, the body waveguide layer 403 is located between the body buried layer 401 and the body upper cladding layer 402. The body buried layer 401 is located between the body waveguide layer 403 and the substrate 400. The thickness of the body buried layer 401 is equal to the sum of the thicknesses of the buried layer 201 and the support layer 202. The body waveguide layer 403 includes a body upper waveguide layer 4032 and a body lower waveguide layer 4031. The thickness of the body upper waveguide layer 4032 is equal to the thickness of the upper waveguide layer 2032. The thickness of the body lower waveguide layer 4031 is equal to the thickness of the lower waveguide layer 2031. The width of the body lower waveguide layer 4031 is equal to the width of the lower waveguide layer 2031. The material of the body upper cladding layer 402 can be silicon oxynitride, oxide, or fluoride, etc. The material of the body burial layer 401 can be an oxide or a fluoride, etc.

[0077] Figure 4b This is a second top view of the optical coupler provided in this application. Figure 4b As shown, the optical coupler includes a protrusion and a local portion. The protrusion is located between sections 1 and 5. A description of the protrusion can be found in the preceding text. Figure 2c The relevant description is as follows. The main body is located between section 5 and section 6. Section 5 is the cutoff section of the support layer 202. Section 6 is the cutoff section of the optical coupler. Figure 4c This is a schematic diagram of the sixth cross-section of the optical coupler provided in this application. Figure 4c This is a schematic diagram of section 6. Figure 4c This can also be referred to as the right view of an optical coupler. For example... Figure 4c As shown, the optical coupler includes a substrate 400, a body buried layer 401, a body waveguide layer 403, and a body upper cladding layer 402. The body waveguide layer 403 includes a body upper waveguide layer 4032 and a body lower waveguide layer 4031. The body upper waveguide layer 4032 and the body lower waveguide layer 4031 are covered by the body upper cladding layer 402.

[0078] exist Figure 4a In the optical coupler, the width of the body is equal to the width of the protrusion. In practical applications, the width of the body can be greater than the width of the protrusion. In this case, the body can connect to multiple protrusions. For example, Figure 5 This is a schematic diagram of the optical coupler provided in this application. Figure 5As shown, the optical coupler includes a main body 500. Three protrusions are connected to the side of the main body. The three protrusions are protrusion 501, protrusion 502, and protrusion 503.

[0079] The optical coupler in this application has been described above; the optical chip in this application will be described below. Figure 6 This is a schematic diagram of the structure of the optical chip provided in this application. Figure 6 As shown, the optical chip 600 includes an optical coupler 601 and a first optical device 602. A description of the optical coupler 601 can be found in the foregoing. Figures 2a to 2h and Figures 3-5 The description in [the document] states that optical coupler 601 is used to receive the reversed optical signal from second optical device 603. Optical coupler 601 is used to reduce the mode shape of the reversed optical signal, obtaining a reduced-mode reversed optical signal. For example, second optical device 603 is an optical fiber. Figures 2a-2c In the optical coupler 601, the optical fiber is coupled to the left end face (section 1). The center of the optical fiber is aligned with the center of the waveguide layer 203 in the optical coupler 601. The optical coupler 601 receives the reverse optical signal from the left end face. As the reverse optical signal propagates in the reverse direction within the optical coupler 601, the energy of the reverse optical signal gradually concentrates in the waveguide layer 203, causing the mode size of the reverse optical signal to gradually decrease. The optical coupler 601 is also used to transmit the reduced-mode-size reverse optical signal to the first optical device 602. The first optical device 602 is used to process the reverse optical signal. For example, the first optical device 602 is an optical transceiver module. The optical transceiver module is used to demodulate the reverse optical signal to obtain the input electrical signal. It should be understood that the first optical device 602 can also be a wavelength division multiplexer, wavelength demultiplexer, optical switch, mode converter, multiplexer, or beam splitter, etc.

[0080] In practical applications, the first optical device 602 can also be used to transmit forward optical signals to the optical coupler 601. For example, the first optical device 602 is an optical transceiver module. The optical transceiver module is used to obtain a forward optical signal by modulating the output electrical signal. The optical transceiver module is used to transmit the forward optical signal to the optical coupler 601. The optical coupler 601 is used to amplify the mode of the forward optical signal to obtain the amplified forward optical signal. For example, in... Figures 2a-2c In the first optical device 602, the optical coupler 601 is coupled to its right end face (section 5). The optical coupler 601 receives the forward optical signal from its right end face. As the forward optical signal propagates in the optical coupler 601 along the forward transmission direction, its energy is gradually dispersed in the upper cladding 204, causing the beam pattern of the forward optical signal to gradually amplify. The optical coupler 601 is used to transmit the amplified forward optical signal to the second optical device 603.

[0081] Among them, when the optical coupler 601 is Figure 5The optical coupler shown includes multiple protrusions. Optical coupler 601 can be connected to multiple second optical devices. Each second optical device corresponds one-to-one with a protrusion. Multiple optical signals transmitted through the protrusions can have the same wavelength or different wavelengths. For example, when the first optical device 602 is a beam splitter, the multiple optical signals have the same wavelength. When the first optical device 602 is a wavelength divider, the multiple optical signals have different wavelengths.

[0082] In practical applications, the second optical device 603 can also be an optical switch or a mode converter, etc. In this case, the second optical device 603 can be integrated on the optical chip 600, that is, the optical chip 600 can also include the second optical device 603.

[0083] The optical chip in this application has been described above; the optical communication device in this application will be described below. Figure 7 This is a schematic diagram of the structure of the optical communication device provided in this application. Figure 7 As shown, the optical communication device 700 includes an optical chip 701 and a processor 702. A description of the optical chip 701 can be found in the description above (section 6). The optical chip 701 is used to receive a reverse optical signal and obtain an input electrical signal based on the reverse optical signal. Specifically, the optical chip 701 includes an optical coupler and an optical transceiver module. The optical coupler 701 is used to reduce the mode shape of the reverse optical signal, obtaining a reduced-mode reverse optical signal. The optical transceiver module is used to demodulate the reverse optical signal to obtain the input electrical signal. The processor 702 is used to perform data processing on the input electrical signal.

[0084] Processor 702 may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and an NP. Processor 702 may further include a hardware chip or other general-purpose processor. The aforementioned hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0085] In other embodiments, the processor 702 can also be used to generate an output electrical signal. The optical chip 701 is further used to obtain a forward optical signal based on the output electrical signal and to output the forward optical signal. For example, the optical chip 701 is an optical transceiver module. The optical transceiver module is used to modulate the output electrical signal to obtain a forward optical signal. The optical coupler is used to amplify the mode of the forward optical signal to obtain a forward optical signal with amplified mode. The optical coupler is used to output the forward optical signal with amplified mode.

[0086] The optical communication equipment in this application has been described above; the optical communication system in this application will be described below. Figure 8 This is a schematic diagram of the optical communication system provided in this application. Figure 8 As shown, the optical communication system includes a first optical communication device 801 and a second optical communication device 802. The first optical communication device 801 and the second optical communication device 802 are connected via optical fiber. The first optical communication device 801 and the second optical communication device 802 can be referenced from the aforementioned... Figure 7 Description of Zhongguang Communication Equipment 700.

[0087] The first optical communication device 801 includes an optical chip and a processor. The processor is used to generate an output electrical signal. The optical chip is used to obtain a forward optical signal based on the output electrical signal. Specifically, the optical chip includes an optical coupler and an optical transceiver module. The optical transceiver module is used to obtain the forward optical signal by modulating the output electrical signal. The optical coupler is used to amplify the mode of the forward optical signal to obtain an amplified forward optical signal. The optical coupler is used to output the amplified forward optical signal to an optical fiber.

[0088] The forward optical signal transmitted by the first optical communication device 801 serves as the reverse optical signal for the second optical communication device 802. The second optical communication device 802 receives the reverse optical signal via optical fiber. The second optical communication device 802 includes an optical chip and a processor. The optical chip receives the reverse optical signal and obtains an input electrical signal based on it. Specifically, the optical chip includes an optical coupler and an optical transceiver module. The optical coupler reduces the mode shape of the reverse optical signal to obtain a reduced-mode reverse optical signal. The optical transceiver module demodulates the reverse optical signal to obtain the input electrical signal. The processor performs data processing on the input electrical signal.

[0089] Similarly, in practical applications, the second optical communication device 802 can send a forward optical signal to the first optical communication device 801 via optical fiber. The forward optical signal sent by the second optical communication device 802 serves as the reverse optical signal for the first optical communication device 801. The first optical communication device 801 receives the reverse optical signal.

[0090] The optical communication system in this application has been described above. The fabrication method of the optical coupler in this application will be described below. Figure 9 This is a schematic flowchart illustrating the fabrication method of the optical coupler provided in this application. Figure 9 As shown, the fabrication method of the optical coupler includes the following steps.

[0091] In step 901, a wafer is provided. In the height direction, the wafer includes a substrate, a bottom layer, and a waveguide layer. The bottom layer is located between the waveguide layer and the substrate.

[0092] In step 902, both sides of the wafer are etched to a depth reaching the interior of the underlying layer, dividing the underlying layer into a support portion and a buried layer of different widths. In the height direction, the support portion lies between the buried layer and the waveguide layer. The width of the support layer is smaller than the width of the buried layer. The width of the etched waveguide layer is smaller than the width of the buried layer. For example, a layer of chromium can be deposited as a hard mask on a wafer with a substrate, an underlying layer, and a waveguide layer. Then, photoresist is spin-coated, and the waveguide layer pattern is exposed using a photolithography machine or an electron beam lithography machine. Dry etching of metallic chromium is performed using the photoresist as a mask. Dry etching of the wafer is performed using metallic chromium as a mask, with an etching depth equal to the thickness of the waveguide layer and the support portion. After etching, the hard mask is removed by wet etching.

[0093] In step 903, an upper cladding layer is epitaxially grown on the etched wafer. For example, a plasma-enhanced chemical vapor deposition (PECVD) apparatus can be used to grow the upper cladding layer on the etched wafer.

[0094] After the top cladding is grown, a patterned mask for the top cladding waveguide can be fabricated using chromium plating, photolithography, and dry etching. Dry etching of the top cladding using metallic chromium as a mask results in a square or circular shape in the width direction.

[0095] In step 902, the waveguide layer and the support layer are obtained in the same etching process. In practical applications, by increasing the number of etching operations, upper and lower waveguide layers with different widths can be formed. In this case, in the height direction, the lower waveguide layer is located between the support layer and the upper waveguide layer, and the width of the lower waveguide layer is greater than the width of the lower waveguide.

[0096] It should be understood that the description of the fabrication method of the optical coupler can be found in the foregoing description of the optical coupler. For example, the optical coupler may also include a substrate. For example, in the transmission direction, the support layer has a trapezoidal structure. The width of the trapezoidal structure gradually decreases along the positive transmission direction. For example, the optical coupler may also include a local portion. For example, the upper waveguide layer includes a first part and a second part. In the transmission direction, the first part has a rectangular structure, and the second part has a trapezoidal structure. The width of the trapezoidal structure gradually decreases along the positive transmission direction.

[0097] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. An optical coupler, characterized in that, include: Buried layer, support layer, waveguide layer, and cladding layer; In the height direction, the support layer is located between the buried layer and the waveguide layer, and the waveguide layer is located between the support layer and the upper cladding layer. In the width direction, the waveguide layer and the support layer are located inside the upper cladding, and the waveguide layer and the support layer are made of different materials; The waveguide layer includes an upper waveguide layer and a lower waveguide layer. The upper waveguide layer and the lower waveguide layer are used to expand the mode of the optical signal transmitted along the positive transmission direction in the height direction. The lower waveguide layer is located between the support layer and the upper waveguide layer. In the width direction, the width of the lower waveguide layer is greater than the width of the upper waveguide layer. In the transmission direction, the projection of the lower waveguide layer on the buried layer coincides with the projection of the support layer on the buried layer. The upper waveguide layer includes a first part and a second part. In the transmission direction, the first part has a rectangular structure and the second part has a trapezoidal structure. In the transmission direction, the lower waveguide layer includes a third end face and a fourth end face, the width of the third end face is greater than the width of the fourth end face, and the lower waveguide layer has a trapezoidal structure; In the height direction, the support layer is located between the buried layer and the waveguide layer. The width of the support layer is smaller than the width of the buried layer, and the width of the waveguide layer is smaller than the width of the buried layer. The support layer and the buried layer are formed by etching the same material layer.

2. The optical coupler according to claim 1, characterized in that, In the width direction, the distance between the center position of the waveguide layer and the center position of the upper cladding layer is less than 50 nanometers.

3. The optical coupler according to claim 1 or 2, characterized in that, In the width direction, the upper cladding layer is square or circular in shape.

4. The optical coupler according to claim 3, characterized in that, The optical coupler is used to connect to an optical fiber with a diameter of b micrometers; Wherein, the width 'a' of the square is within the range b ± 0.5 micrometers, or the diameter 'a' of the circle is within the range b ± 0.5 micrometers.

5. The optical coupler according to any one of claims 1 to 2, characterized in that, In the transmission direction, the support layer includes a first end face and a second end face, wherein the area of ​​the first end face is larger than the area of ​​the second end face.

6. The optical coupler according to claim 5, characterized in that, The width of the support layer gradually decreases along the direction from the first end face to the second end face.

7. The optical coupler according to claim 5, characterized in that, The width of the second end face is less than 120 nanometers.

8. The optical coupler according to claim 5, characterized in that, In the transmission direction, the upper cladding covers the second end face.

9. The optical coupler according to claim 1, characterized in that the width of the first portion is between 400 nanometers and 2000 nanometers, and the minimum width of the trapezoidal structure is less than 120 nanometers.

10. The optical coupler according to claim 1 or 9, characterized in that the width of the fourth end face is less than 120 nanometers.

11. The optical coupler according to any one of claims 1 to 2, characterized in that, The refractive index of the material of the upper cladding layer is greater than that of the material of the support layer.

12. The optical coupler according to any one of claims 1 to 2, characterized in that, The refractive index of the material in the support layer is less than that of the material in the waveguide layer.

13. The optical coupler according to any one of claims 1 to 2, characterized in that, The material of the support layer is silicon dioxide.

14. The optical coupler according to any one of claims 1 to 2, characterized in that, The optical coupler also includes a substrate, and in the height direction, the buried layer is located between the substrate and the support layer.

15. The optical coupler according to any one of claims 1 to 2, characterized in that, The optical coupler also includes a body section; The body portion further includes a body buried layer, a body waveguide layer, and a body upper cladding layer. The body waveguide layer is located between the body buried layer and the body upper cladding layer, and the body waveguide layer and the waveguide layer have the same thickness.

16. An optical chip, characterized in that, Includes the first optical device and the optical coupler as described in any one of claims 1 to 15; The optical coupler is used to receive the reverse optical signal, reduce the mode of the reverse optical signal, obtain the reverse optical signal with reduced mode, and transmit the reverse optical signal with reduced mode to the first optical device; The first optical device is used to receive the reverse light signal after the reduced pattern size and to process the reverse light signal.

17. The optical chip according to claim 16, characterized in that, The first optical device is also used to transmit a forward optical signal to the optical coupler; The optical coupler is used to amplify the pattern of the forward optical signal and output the amplified pattern of the forward optical signal.

18. An optical communication device, characterized in that, Includes a processor and the optical chip as described in claim 16 or 17; The optical chip is used to receive the reverse optical signal and obtain the input electrical signal based on the reverse optical signal; The processor is used to process the input electrical signal.

19. The optical communication device according to claim 18, characterized in that, The processor is also used to generate an output electrical signal and transmit the output electrical signal to the optical chip; The optical chip is also used to obtain a forward optical signal based on the output electrical signal and output the forward optical signal.

20. A method for fabricating an optical coupler, characterized in that, include: A wafer is provided, which includes a substrate, a bottom layer, and a waveguide layer in the height direction, the bottom layer being located between the waveguide layer and the substrate; The wafer is etched on both sides to a depth reaching the interior of the underlying layer, dividing the underlying layer into a support layer and a buried layer of different widths. In the height direction, the support layer lies between the buried layer and the waveguide layer, and its width is smaller than that of the buried layer. The etched width of the waveguide layer is also smaller than that of the buried layer. The waveguide layer includes an upper waveguide layer and a lower waveguide layer, which are used to expand the mode of the optical signal propagating in the positive transmission direction in the height direction. The lower waveguide layer lies between the support layer and the upper waveguide layer. In the width direction, the lower waveguide layer is wider than the upper waveguide layer. The width of the layer; in the transmission direction, the projection of the lower waveguide layer onto the buried layer and the projection of the support layer onto the buried layer coincide; the upper waveguide layer includes a first part and a second part, in the transmission direction, the first part is a rectangular structure and the second part is a trapezoidal structure; in the transmission direction, the lower waveguide layer includes a third end face and a fourth end face, the width of the third end face is greater than the width of the fourth end face, and the lower waveguide layer is a trapezoidal structure; in the height direction, the support layer is located between the buried layer and the waveguide layer, the width of the support layer is less than the width of the buried layer, and the width of the waveguide layer is less than the width of the buried layer; An upper cladding layer is epitaxially grown on the etched wafer.

21. The preparation method according to claim 20, characterized in that, The method further includes: The upper cladding is etched so that, in the width direction, the upper cladding is square or circular in shape.

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