A photonic integrated chip and a communication device

Abstract

This application provides a photonic integrated chip and a communication device, relating to the field of photonic integration technology, to address the problem of narrow coupling bandwidth of grating couplers in photonic integrated chips. The photonic integrated chip includes a waveguide layer and a cover layer located on one side of the waveguide layer. The outer surface of the cover layer away from the waveguide layer includes an optical port region. A grating coupler is disposed in the waveguide layer for transmitting optical signals to the cover layer. A dispersion compensation structure is disposed in the cover layer for transmitting optical signals emitted from the grating coupler to the optical port region. The dispersion compensation structure includes diffractive optical elements for compressing the dispersion angle between optical signals of different wavelengths. The above-described photonic integrated chip can be applied to communication devices.

Description

Technical Field

[0001] This application relates to the field of photonic integration technology, and more particularly to a photonic integrated chip and a communication device. Background Technology

[0002] A photonic integrated circuit (PIC) is a chip that contains two or more photonic elements and can perform at least one optical function, such as transmitting / receiving optical signals, and performing wavelength division multiplexing and demultiplexing in wavelength division multiplexing scenarios.

[0003] Some photonic integrated chips in related technologies incorporate grating couplers (GCs). These GCs serve as interface devices for the photonic integrated chip, enabling optical signal coupling between the chip and a coupling element (such as an optical fiber). However, the dispersion problem inherent in grating couplers results in a narrow coupling bandwidth. Summary of the Invention

[0004] This application provides a photonic integrated chip and a communication device to improve the problem of narrow coupling bandwidth of grating couplers in photonic integrated chips.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect, a photonic integrated chip is provided, which includes a waveguide layer and a cover layer located on one side of the waveguide layer. The outer surface of the cover layer away from the waveguide layer includes an optical port region. A grating coupler is disposed in the waveguide layer for transmitting optical signals to the cover layer.

[0007] The cover plate layer is provided with a dispersion compensation structure, which is used to transmit the optical signal emitted from the grating coupler to the optical port area; the dispersion compensation structure includes diffractive optical elements, which are used to compress the dispersion angle between optical signals of different wavelengths.

[0008] In the photonic integrated chip provided in this application, the dispersion angle between light signals of different wavelengths emitted from the grating coupler can be compressed by the diffraction optical element in the dispersion compensation structure, thereby realizing the function of dispersion compensation of the grating coupler, which can improve the coupling bandwidth of the grating coupler and meet the high-density and high-bandwidth coupling scenarios of the photonic integrated chip.

[0009] In some possible implementations, the dispersion compensation structure includes a first reflective element and a second reflective element disposed opposite to each other in a direction perpendicular to the waveguide layer. The first and second reflective elements are used to transmit the optical signal emitted from the grating coupler to the optical port region after at least two reflections. At least one of the first and second reflective elements is a diffractive optical element, and the diffractive optical element is a reflective diffractive optical element.

[0010] This design extends the transmission path of light signals in the dispersion compensation structure through reflection, thereby facilitating the processing of light signals by the diffractive optical elements in the dispersion compensation structure.

[0011] In some possible implementations, the first reflective element is a reflective diffractive optical element, and the second reflective element is a metallic reflective layer or a Bragg reflective layer. This design suffices to fabricate only the first reflective element as a reflective diffractive optical element, which, while achieving dispersion compensation, helps reduce the fabrication difficulty and cost of the dispersion compensation structure.

[0012] In some possible implementations, the first reflective element includes a first functional portion and a second functional portion spaced apart, the first functional portion being used to reflect the optical signal emitted from the grating coupler to the second reflective element, and the second functional portion being used to reflect the optical signal emitted from the second reflective element to the second reflective element.

[0013] The second reflective element is used to reflect the optical signal emitted from the first functional part to the second functional part, and also to reflect the optical signal reflected from the second functional part to the optical port area.

[0014] The dispersion compensation structure designed above allows the light signal to be transmitted to the optical port region after four reflections between the first and second reflecting elements. During these four reflections, the light signal passes through the first reflecting element (a reflective diffractive optical element) twice—once through the first active part and once through the second active part. In this case, the processing of the light signal can be divided into two steps. Compared to single-step processing, two-step processing reduces the complexity of the diffractive optical element and improves the processing effect while achieving the same desired processing effect. For example, dispersion compensation can be implemented by processing the light signal in two steps: a preliminary dispersion compensation is performed first, followed by a second dispersion compensation, achieving the final dispersion compensation effect through these two steps.

[0015] In some possible implementations, the first reflective element is disposed at the top of the cover layer away from the waveguide layer, and the second reflective element is disposed at the bottom of the cover layer near the waveguide layer or within the cover layer. This design facilitates the fabrication of the first reflective element at the top of the cover layer, which helps reduce the fabrication difficulty and cost of the dispersion compensation structure. Furthermore, the second reflective element in the dispersion compensation structure can be disposed at different positions within the cover layer, offering flexibility and adaptability to various fabrication processes.

[0016] In some possible implementations, the cover layer includes an upper cladding layer and a dielectric layer. The upper cladding layer is disposed on one side of the waveguide layer, and the dielectric layer is disposed on the side of the upper cladding layer away from the waveguide layer, covering a portion of the upper cladding layer. The second reflective element is disposed on the upper cladding layer near the bottom of the waveguide layer or on the dielectric layer near the bottom of the upper cladding layer.

[0017] In the photonic integrated chip provided in this application, the dispersion compensation structure can be disposed in a cover layer that partially covers the dielectric layer. The upper cladding and dielectric layer in the cover layer can be made of the same or different materials, thereby adapting to different types of photonic integrated chips. Based on this, it is also advantageous to use different fabrication processes to fabricate the dispersion compensation structure, such as using complementary metal-oxide-semiconductor (CMOS) processes compatible with photonic integrated systems.

[0018] In some possible implementations, the cover layer includes an upper cladding layer and a dielectric layer, with the upper cladding layer disposed on one side of the waveguide layer and the dielectric layer disposed on the side of the upper cladding layer away from the waveguide layer; the upper cladding layer and the dielectric layer are made of different materials; the second reflective element is disposed on the upper cladding layer near the bottom of the waveguide layer or on the dielectric layer near the bottom of the upper cladding layer.

[0019] In the photonic integrated chip provided in this application, the dispersion compensation structure can be disposed in a cover layer with different materials for the dielectric layer and the upper cladding layer, thereby adapting to different types of photonic integrated chips. Based on this, it is also advantageous to use different fabrication processes to fabricate the dispersion compensation structure, such as using complementary metal-oxide-semiconductor (CMOS) processes compatible with photonic integrated systems.

[0020] In some possible implementations, the reflective diffractive optical element includes a microstructure layer, a reflective Bragg grating, or a freeform surface. In the photonic integrated chip provided in this application, the dispersion compensation structure can adopt different structures as the reflective diffractive optical element, offering flexible and diverse structural selection to adapt to different application scenarios.

[0021] In some possible implementations, the reflective diffractive optical element includes a microstructure layer and a reflective film, with the reflective film disposed on the side of the microstructure layer away from the waveguide layer. This design allows for an increase in the reflectivity of the reflective diffractive optical element through the reflective film, thereby improving the performance of the dispersion compensation structure.

[0022] In some possible implementations, the diffractive optical element is a transmission-type diffractive optical element and is disposed in the transmission path of the optical signal in the cover plate layer. In the photonic integrated chip provided in this application, the dispersion compensation structure can also adopt a transmission-type diffractive optical element, which provides flexible and diverse structural selection and can adapt to different application scenarios.

[0023] In some possible implementations, diffractive optical elements are also used to shape the optical signal pattern. This design enables the optical signal to have a pattern that matches the coupler (e.g., optical fiber) when it is transmitted to the optical port region, thereby improving the coupling efficiency between the grating coupler and the coupler (e.g., optical fiber).

[0024] In some possible implementations, the photonic integrated chip includes an anti-reflection coating disposed on the outer side of the optical port region. By providing the anti-reflection coating, the interface loss when the optical signal is coupled to the coupling element (e.g., optical fiber) through the optical port region can be reduced, thereby improving the coupling efficiency.

[0025] In some possible implementations, the dispersion compensation structure further includes a microlens disposed in the optical port region of the cover plate layer. The microlens is used to shape the mode pattern of the optical signal. This design allows the mode pattern of the dispersion-compensated optical signal to be shaped through transmission via the microlens, thereby improving the coupling efficiency between the grating coupler and the coupling element (e.g., optical fiber). Furthermore, the mode-shaping function of the microlens can offload the functions of diffractive optical elements, thus reducing the design complexity of diffractive optical elements and improving the processing effect of optical signals.

[0026] In some possible implementations, the thickness of the cover layer is greater than 100 micrometers in the direction perpendicular to the waveguide layer. This design can increase the transmission distance of the optical signal in the dispersion compensation structure, thereby facilitating the arrangement of the dispersion compensation structure and the processing of the optical signal by the diffractive optical elements in the dispersion compensation structure.

[0027] In some possible implementations, the photonic integrated chip is an optoelectronic co-packaged structure that includes an electronic integrated circuit. Since the interface between the dispersion compensation structure and the optical signal is located inside the cover layer, contamination that may occur during the back-end packaging process of the electronic integrated circuit, such as molding and reflow soldering, will not directly affect the functional portion of the dispersion compensation structure, thus achieving a certain degree of contamination resistance. Therefore, it can be seen that the photonic integrated chip provided in this application has certain advantages in optoelectronic co-packaging scenarios.

[0028] In a second aspect, a communication device is provided, comprising a photonic integrated chip as described in the first aspect and a coupling element, wherein the coupling element is coupled in the optical port region of the photonic integrated chip for transmitting optical signals through the optical port region.

[0029] The technical effects achievable by the communication equipment provided in this application are the same as those achievable by the photonic integrated chip in the first aspect, and will not be repeated here. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a photonic integrated chip provided in an embodiment of this application;

[0031] Figure 2 for Figure 1 A schematic diagram of the dispersion of the grating coupler;

[0032] Figure 3 This is a schematic diagram of another photonic integrated chip provided in an embodiment of this application;

[0033] Figure 4 This is a schematic diagram of the structure of a first reflective element 11 provided in an embodiment of this application;

[0034] Figure 5 This is a schematic diagram of another first reflective element 11 provided in an embodiment of this application;

[0035] Figure 6 A schematic diagram illustrating the principle of dispersion compensation for a reflective diffractive optical element provided in an embodiment of this application;

[0036] Figure 7 This is a schematic diagram of the structure of another photonic integrated chip provided in the embodiments of this application;

[0037] Figure 8 This is a schematic diagram of the structure of another photonic integrated chip provided in the embodiments of this application;

[0038] Figure 9 This is a schematic diagram of the structure of another photonic integrated chip provided in the embodiments of this application;

[0039] Figure 10 This is a schematic diagram of the structure of another photonic integrated chip provided in the embodiments of this application;

[0040] Figure 11 This is a schematic diagram of the structure of another photonic integrated chip provided in the embodiments of this application. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0042] In the following embodiments of this application, the terms "first," "second," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0043] In the embodiments of this application, "upper", "lower", "left" and "right" are not limited to the orientation of the components in the accompanying drawings. It should be understood that these directional terms can be relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the components in the accompanying drawings.

[0044] In the embodiments of this application, unless the context otherwise requires, the term "comprising" is interpreted as open and encompassing throughout the specification and claims, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "exemplarily," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this application. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0045] As used herein, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from the given value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the given quantity (i.e., the limitations of the measurement system).

[0046] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable range of deviation for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable range of deviation for approximate perpendicularity may also be, for example, within 5°; “equal” includes absolute equality and approximate equality, where an acceptable range of deviation for approximate equality may be, for example, a difference between the two equals being less than or equal to 5% of either one.

[0047] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0048] Exemplary embodiments are described in this application with reference to cross-sectional views and / or plan views and / or equivalent circuit diagrams, which are idealized exemplary drawings. In the drawings, the thickness of layers and regions is enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched regions shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0049] This application provides a photonic integrated circuit (PIC) chip, such as... Figure 1As shown, the photonic integrated chip 1 includes a substrate 2, a lower cladding layer 3, a waveguide layer 4, and an upper cladding layer 5 stacked together. The substrate 2 can be made of at least one of silicon (Si), silicon dioxide (SiO2), silicon germanium (SiGe), silicon carbide (SiC), silicon nitride (SiN), indium phosphide (InP), gallium arsenide (GaAs), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), and glass. The lower cladding layer 3, waveguide layer 4, and upper cladding layer 5, by using a combination of materials with different refractive indices, form a total internal reflection structure that confines the optical signal within the waveguide layer 4 for transmission. Optical structures for processing the optical signal can also be fabricated in the waveguide layer 4. The lower cladding layer 3, waveguide layer 4, and upper cladding layer 5 can be selected based on factors such as the material of the substrate 2, the fabrication process of the photonic integrated chip 1, and the function of the photonic integrated chip 1.

[0050] For example, the photonic integrated chip 1 can be fabricated using silicon-on-insulator (SOI), which includes a substrate, a buried oxide (BOX) layer, and a top silicon (Device Layer) stacked together. Both the substrate and the top silicon are made of silicon; the substrate provides mechanical support, and the top silicon is used to fabricate the functional structure. The buried oxide layer, made of silicon dioxide (SiO2), is disposed between the substrate and the top silicon to achieve dielectric isolation between them. Corresponding to the photonic integrated chip 1 provided in this embodiment, the substrate serves as the base 2, the buried oxide layer as the lower cladding layer 3, and the top silicon as the waveguide layer 4.

[0051] Please continue to refer to this. Figure 1 The upper cladding layer 5 is disposed on the side of the waveguide layer 4 away from the lower cladding layer 3, and is formed using a semiconductor material with a refractive index lower than that of the waveguide layer 4. The upper cladding layer 5 can be made of the same material as the lower cladding layer 3. In this embodiment, both the upper cladding layer 5 and the lower cladding layer 3 can be made of silicon dioxide, and the upper cladding layer 5 can be fabricated, for example, by chemical vapor deposition (CVD).

[0052] The upper cladding 5 has an optical port region 8 on its outer surface away from the waveguide layer 4. When the photonic integrated chip 1 is in use, the coupler 7 (e.g., an optical fiber) can be coupled to the photonic integrated chip 1 in the optical port region 8. A grating coupler (GC) 6 is disposed in the waveguide layer 4. The grating coupler 6 can deflect the optical signal to one side of the upper cladding 5 based on the diffraction effect of the Bragg grating and project it into the optical port region 8. The optical signal emitted from the grating coupler 6 enters the coupler 7 (e.g., an optical fiber) through the optical port region 8. Exemplarily, the grating coupler 6 can adopt a grating structure of single-period, double-period, shallow-etched, deep-etched, uniform, apodized, chirped, or double-layer types.

[0053] It can be seen that the photonic integrated chip 1 provided in this application embodiment adopts a vertical optical port design, and the grating coupler 6 is an interface device for the internal and external transmission of optical signals in the photonic integrated chip 1, used to realize the optical signal coupling between the photonic integrated chip 1 and the coupling element 7 (e.g., optical fiber).

[0054] However, as Figure 2 As shown, due to the dispersion problem of the grating coupler 6, when the optical signal includes multiple wavelengths (in... Figure 2 When λ1, λ2, and λ3 are used for illustration, the grating coupler 6 deflects optical signals of different wavelengths at different angles, resulting in differences in the exit angle of optical signals of different wavelengths exiting the grating coupler 6. In other words, optical signals of different wavelengths are not collimated but exhibit a certain divergence angle, also known as the dispersion angle. Under these circumstances, speckle diffusion occurs during the transmission of optical signals of different wavelengths from the grating coupler 6 to the optical port region 8, preventing some wavelengths from entering the coupling element 7 (e.g., optical fiber) through the optical port region 8. Consequently, the coupling bandwidth of the grating coupler 6 is generally narrow.

[0055] In addition, since the optical signal emitted from the grating coupler 6 has a complex and irregular pattern, there is a pattern mismatch with the conventional type of coupling element 7 (e.g., optical fiber), which leads to a problem of low coupling efficiency between the grating coupler 6 and the coupling element 7 (e.g., optical fiber).

[0056] Based on this, this application also provides a photonic integrated chip 1, such as... Figure 3 As shown, the difference between this photonic integrated chip 1 and the photonic integrated chip 1 in the above embodiment is that the photonic integrated chip 1 has an additional dielectric layer 9 on the outer surface of the upper cladding 5 away from the waveguide layer 4, and the optical port region 8 is disposed in the outer surface of the dielectric layer 9 away from the waveguide layer 4; and a dispersion compensation structure 13 is provided between the grating coupler 6 and the optical port region 8.

[0057] For ease of description, this paper will collectively refer to the upper cladding layer 5 and the dielectric layer 9 as the cover layer 10. For example... Figure 3 As shown, in the photonic integrated chip 1 provided in this embodiment, the dispersion compensation structure 13 includes a first reflective element 11 and a second reflective element 12 disposed in the cover layer 10, that is, both the first reflective element 11 and the second reflective element 12 are located on the side of the waveguide layer 4 away from the lower cladding layer 3. The first reflective element 11 and the second reflective element 12 are disposed opposite to each other in a direction perpendicular to the waveguide layer 4, and the first reflective element 11 is located away from the waveguide layer 4 relative to the second reflective element 12.

[0058] The first reflective element 11 is used to receive the optical signal emitted from the grating coupler 6 and reflect the optical signal toward the side where the second reflective element 12 is located.

[0059] In this embodiment, the first reflective element 11 is disposed on the top of the dielectric layer 9 away from the waveguide layer 4, and is a reflective diffractive optical element (DOE). This reflective diffractive optical element can be a microstructure layer disposed on the dielectric layer 9. The microstructure layer includes multiple microstructures, which can be sawtooth structures or stepped structures, etc. This microstructure layer can form a microstructure reflective interface on the dielectric layer 9. Different microstructures in the microstructure layer can form different microstructure reflective interfaces, and different microstructure reflective interfaces can produce different phase delays to the optical signal while reflecting it. Therefore, by designing parameters such as the morphology, size, and distribution of the microstructures in the microstructure layer, the morphology of the microstructure reflective interface can be designed, thereby achieving phase modulation of the optical signal while reflecting it.

[0060] For example, such as Figure 4 As shown, the microstructure layer 14 includes a stepped structure 15 recessed towards the waveguide layer 4, disposed on the outer surface of the dielectric layer 9 away from the waveguide layer 4. This stepped structure 15 can be formed by etching the top of the dielectric layer 9. For the aforementioned microstructure layer 14, the side near the grating coupler 6 is the dielectric layer 9 (silicon dioxide), and the side away from the grating coupler 6 is air; thus, the microstructure layer 14 forms a microstructure reflective interface on the dielectric layer 9 capable of reflecting optical signals. Furthermore, by designing parameters such as the size, depth, and distribution characteristics of the stepped structure 15, the morphology of the microstructure reflective interface can be designed, thereby achieving phase modulation of the optical signal while reflecting it.

[0061] In some embodiments, such as Figure 5As shown, the first reflective element 11 employs a reflective diffractive optical element that further includes a reflective film 16. The reflective film 16 is disposed on the side of the microstructure layer 14 away from the waveguide layer 4 and is made of a high-reflectivity material. For example, the material used to fabricate the reflective film 16 can be a metal such as aluminum (Al), silver (Ag), or gold (Au), or a dielectric material such as titanium dioxide (TiO2), zinc sulfide (ZnS), or tantalum pentoxide (Ta2O5). By providing the reflective film 16, the reflection efficiency of the microstructure reflective interface formed by the microstructure layer 14 can be increased, thereby improving the performance of the microstructure reflective interface.

[0062] In the photonic integrated chip 1 provided in this application embodiment, a microstructure reflective interface with a specific morphology is formed by designing the microstructure layer 14. The first reflective element 11 with the microstructure reflective interface can reflect the light signal emitted from the grating coupler 6 to the side where the second reflective element 12 is located, and is also used to compress the dispersion angle between light signals of different wavelengths, that is, to realize the function of dispersion compensation.

[0063] For ease of understanding, the following text will use first and second optical signals of different wavelengths as examples to illustrate the principle of dispersion compensation achieved by the first reflective element 11.

[0064] like Figure 6 As shown, due to the dispersion of the grating coupler 6, when the first optical signal λ1 and the second optical signal λ2 of different wavelengths are emitted from the grating coupler 6, relative to the reference line perpendicular to the waveguide layer 4, the emission angle of the first optical signal λ1 is the first emission angle θ1, and the emission angle of the second optical signal λ2 is the second emission angle θ2. The first emission angle θ1 is less than the first emission angle θ2, and the dispersion angle between the first optical signal λ1 and the second optical signal λ2 is the angle difference between the second emission angle θ2 and the first emission angle θ1.

[0065] After the first optical signal λ1 and the second optical signal λ2 are emitted from the grating coupler 6, they are transmitted to the first reflective element 11. Due to the dispersion angle, speckle expansion will occur during transmission. When the first optical signal λ1 and the second optical signal λ2 are transmitted to the first reflective element 11, they will illuminate different areas of the first reflective element 11. In this paper, the area of ​​the first optical signal λ1 illuminating the first reflective element 11 is called the first illumination area, and the area of ​​the second optical signal λ2 illuminating the first reflective element 11 is called the second illumination area.

[0066] By designing the first reflective element 11, the microstructure reflective interface in the first illumination region reflects and diffracts and deflects the first optical signal λ1 simultaneously; similarly, the microstructure reflective interface in the second illumination region reflects and diffracts and deflects the second optical signal λ2 simultaneously. In this paper, the diffraction deflection angle of the microstructure reflective interface relative to the reference line perpendicular to the waveguide layer 4 for the first optical signal λ1 is called the first deflection angle θ3, and the diffraction deflection angle for the second optical signal λ2 is called the second deflection angle θ4. By designing the microstructure reflective interfaces in the first and second illumination regions, the magnitudes of the first deflection angle θ3 and the second deflection angle θ4 can be controlled, thereby compensating for the difference between the first emission angle θ1 and the second emission angle θ2. This reduces the difference in emission angles between the first optical signal λ1 and the second optical signal λ2 when they exit from the first reflective element 11, thus compressing the dispersion angle and achieving dispersion compensation.

[0067] For example, by controlling the first deflection angle θ3 and the second deflection angle θ4, the first optical signal λ1 and the second optical signal λ2 can be emitted from the first reflective element 11 at the same emission angle; that is, the dispersion angle is compressed to 0, so that the first optical signal λ1 and the second optical signal λ2 are emitted in a parallel state.

[0068] From another perspective, the microstructure layer 14 used in the first reflective element 11 can be understood as the "reverse" structure of the grating coupler 6. For light signals of different wavelengths emitted from the grating coupler 6, while being reflected towards the side where the second reflective element 12 is located, a dispersion angle opposite to that of the grating coupler 6 can be generated, thereby achieving the effect of dispersion compensation.

[0069] Please continue to refer to this. Figure 3 The second reflective element 12 is disposed in the cover layer 10, and in a direction perpendicular to the waveguide layer 4, the second reflective element 12 is located on the side of the first reflective element 11 closest to the waveguide layer 4. For example, as shown... Figure 3 As shown, the second reflective element 12 can be disposed in the upper cladding 5 near the bottom of the waveguide layer 4, that is, in the outer surface of the waveguide layer 4 away from the lower cladding 3, with the upper cladding 5 covering the second reflective element 12. Another example is... Figure 7 As shown, the second reflective element 12 can also be disposed on the bottom of the dielectric layer 9 near the upper cladding layer 5, that is, on the outer surface of the upper cladding layer 5 away from the waveguide layer 4, and the dielectric layer 9 covers the second reflective element 12.

[0070] The second reflective element 12 adopts a reflective mirror structure. For example, the first reflective element 11 can be a metal reflective layer or a Bragg reflective layer formed by stacking different dielectric material layers. The second reflective element 12 is used to receive the light signal emitted from the first reflective element 11 and can reflect the light signal to the light port region 8.

[0071] It can be seen that the first reflective element 11 and the second reflective element 12 in the dispersion compensation structure 13 are used to transmit the light signal emitted from the grating coupler 6 to the optical port region 8 after two reflections. In the process of light signal transmission, the first reflective element 11, which adopts a reflective diffractive optical element, can realize the dispersion compensation function of the grating coupler 6, thereby improving the coupling bandwidth of the grating coupler 6. This enables the photonic integrated chip 1 to meet the development requirements of large bandwidth and high density optical ports.

[0072] In addition, as can be seen from the above description, the microstructure layer 14 used in the first reflective element 11 is set to correspond to the illumination position of the light signal after the speckle expansion, which can increase the alignment tolerance between the grating coupler 6 and the first reflective element 11, thereby helping to reduce the processing difficulty.

[0073] In some embodiments, the microstructure layer 14 can be designed so that the formed microstructure reflective interface can achieve dispersion compensation and mode shaping at the same time; thus, when the optical signal is transmitted to the optical port region 8, it has a mode that matches the coupling element 7 (e.g., optical fiber), thereby improving the coupling efficiency between the grating coupler 6 and the coupling element 7 (e.g., optical fiber).

[0074] In some embodiments, the first reflective element 11 may also be a reflective diffractive optical element such as a reflective Bragg grating or a freeform surface, which can achieve the same function as the microstructure layer 14 described above, in order to adapt to different scenarios.

[0075] Please refer to Figure 3 , Figure 8 and Figure 9 In the photonic integrated chip 1 provided in this embodiment, the cover layer 10 includes an upper cladding layer 5 and a dielectric layer 9. The dielectric layer 9 is disposed on the outer surface of the upper cladding layer 5 away from the waveguide layer 4, and the dielectric layer 9 can cover part or all of the upper cladding layer 5. In the thickness direction perpendicular to the waveguide layer 4, the thickness of the upper cladding layer 5 is 1.5 micrometers to 2 micrometers, and the overall thickness of the cover layer 10 is greater than 100 micrometers.

[0076] like Figure 3 and Figure 8As shown, the dielectric layer 9 can be made of the same material as the upper cladding layer 5. Corresponding to the embodiment where the upper cladding layer 5 is made of silicon dioxide, the dielectric layer 9 is also made of silicon dioxide. In this case, there may not be a clear material interface between the dielectric layer 9 and the upper cladding layer 5. In the embodiment where the dielectric layer 9 covers a portion of the upper cladding layer 5, as shown... Figure 8 As shown, the upper cladding layer 5 and the dielectric layer 9 in the cover plate layer 10 can be distinguished by structural features; that is, the dielectric layer 9 corresponds to the protrusion on the outer surface of the upper cladding layer 5. In an embodiment where the dielectric layer 9 covers the entire upper cladding layer 5, as shown... Figure 3 As shown, the upper cladding layer 5 in related technologies and the cover layer 10 in this application embodiment can be distinguished by their thickness; the thickness of the cover layer 10 in this application embodiment is greater than 100 micrometers, which is much greater than the thickness of the upper cladding layer 5 in related technologies.

[0077] The dielectric layer 9, which uses the same material as the upper cladding layer 5, can be formed using the same fabrication method as the upper cladding layer 5. For example, the same process can be used to fabricate the dielectric layer 9 after the upper cladding layer 5 is fabricated; alternatively, the dielectric layer 9 can be fabricated separately and then bonded to the outer surface of the upper cladding layer 5 away from the waveguide layer 4. Since the dielectric layer 9 and the upper cladding layer 5 use the same material, there is no refractive index difference at the bonding interface between them, thus avoiding interface insertion loss.

[0078] In some embodiments, such as Figure 9 As shown, the dielectric layer 9 can be made of a material different from the upper cladding layer 5 but with a similar refractive index. For example, if the upper cladding layer 5 is made of silicon dioxide, the dielectric layer 9 can be made of silicon, silicon nitride (SiN), silicon carbide (SiC), or silicon oxynitride (SiO2). x N y Materials used include aluminum oxide (Al2O3) and aluminum nitride (AlN). This design allows for the use of different materials while minimizing the loss of optical signal transmission due to the refractive index difference between them. Furthermore, regardless of whether the dielectric layer 9 covers part or all of the upper cladding layer 5, there can be a clear material interface between the two, making it relatively easy to distinguish between the upper cladding layer 5 and the dielectric layer 9.

[0079] For the dielectric layer 9, which uses a different material than the upper cladding 5, it can be formed in the same way as the upper cladding 5, or the dielectric layer 9 can be fabricated separately and then bonded to the outer surface of the upper cladding 5 away from the waveguide layer 4.

[0080] The dispersion compensation structure 13 can be formed during the fabrication of the upper cladding layer 5 and the dielectric layer 9. As can be seen from the structure of the dispersion compensation structure 13, its fabrication is compatible with complementary metal-oxide-semiconductor (CMOS) processes, thereby reducing the fabrication difficulty of the photonic integrated chip 1.

[0081] In some embodiments, such as Figure 10 As shown, the dispersion compensation structure 13 includes a microlens 17 disposed in the optical port region 8. The microlens 17 can be formed by processing the dielectric layer 9 or fixed to the dielectric layer 9 by means of bonding or other methods. The microlens 17 can reshape the mode pattern of the dispersion-compensated optical signal through transmission, thereby improving the coupling efficiency between the grating coupler 6 and the coupling element 7 (e.g., optical fiber). Furthermore, the mode-shaping function of the microlens 17 can share the functions of reflective diffractive optical elements, thereby reducing the design difficulty of reflective diffractive optical elements and improving the processing effect of optical signals.

[0082] In some embodiments, the dispersion compensation structure 13 includes an antireflection film disposed in the optical port region 8. The antireflection film is made of a dielectric material such as magnesium fluoride (MgF2), aluminum oxide (Al2O3), aluminum nitride (AlN), or zirconium dioxide (ZrO2). By providing the antireflection film, the interface loss of the optical signal when coupled to the coupling element 7 (e.g., optical fiber) through the optical port region 8 can be reduced.

[0083] In some embodiments, the first reflective element 11 may be a reflective mirror structure, and the second reflective element 12 may be a reflective diffractive optical element. That is, the structures of the two can be interchanged, and they can still achieve the above functions. Their working principle is the same as that of the above embodiments, and will not be repeated here.

[0084] In the above embodiments, the dispersion compensation structure 13 controls the light signal to pass through a reflective diffraction optical element during the process of guiding the light signal emitted from the grating coupler 6 to the optical port region 8; so that the reflective diffraction optical element can perform a preset function on the light signal; however, the embodiments of this application are not limited to this.

[0085] In the photonic integrated chip 1 provided in this application embodiment, the number of reflections of the light signal can be increased by designing the first reflective element 11 and the second reflective element 12, thereby increasing the number of times the light signal passes through the reflective diffraction optical element, that is, increasing the number of times the reflective diffraction optical element acts on the light signal, and improving the processing effect of the light signal emitted from the grating coupler 6.

[0086] In some embodiments, both the second reflective element 12 and the first reflective element 11 are reflective diffractive optical elements, thereby increasing the number of times the reflective diffractive optical element interacts with the optical signal in the same number of reflections, thereby improving the processing effect of the optical signal emitted from the grating coupler 6.

[0087] In some embodiments, such as Figure 11 As shown, the first reflecting element 11 is a reflective diffractive optical element, and the second reflecting element 12 is a reflective mirror structure. The first reflecting element 11 includes a first functional portion 18 and a second functional portion 19. The first functional portion 18 and the second functional portion 19 can be two separate independent structures or different parts of a single integral structure. The first functional portion 18 is used to reflect the optical signal emitted from the grating coupler 6 to the second reflecting element 12, and the second functional portion 19 is used to reflect the optical signal emitted from the second reflecting element 12 to the second reflecting element 12.

[0088] The second reflective element 12 is used to reflect the optical signal emitted from the first functional portion 18 to the second functional portion 19, and also to reflect the optical signal reflected from the second functional portion 19 to the optical port region 8. In this case, the second reflective element 12 can be a single integral structure, or it can be a first sub-part and a second sub-part corresponding to the first reflective element 11 and the second reflective element 12. The first sub-part and the second sub-part can be set at the same height (relative to the waveguide layer 4), or they can be set at different heights.

[0089] The dispersion compensation structure 13 designed above allows the light signal to be transmitted to the optical port region 8 after four reflections between the first reflecting element 11 and the second reflecting element 12. During these four reflections, the light signal passes through the first reflecting element 11 twice, the first active portion 18 once, and the second active portion 19 once. In this case, the processing of the light signal can be divided into two steps. Compared to single-step processing, two-step processing reduces the complexity of the diffractive optical element and improves the processing effect while achieving the same preset processing effect. For example, dispersion compensation can be implemented by processing the light signal in two steps: a preliminary dispersion compensation is performed first, followed by a second dispersion compensation, achieving the final dispersion compensation effect through these two steps.

[0090] In some embodiments, the number of reflections of the optical signal can be increased to more than four by designing the first reflective element 11 and the second reflective element 12, thereby further increasing the number of times the optical signal passes through the reflective diffractive optical element, and further improving the processing effect of the optical signal emitted from the grating coupler 6.

[0091] In the above embodiments, the dispersion compensation structure 13 is described using a reflective diffractive optical element. However, the embodiments of this application are not limited to this. In some embodiments, the dispersion compensation structure 13 includes a transmissive diffractive optical element, and the transmissive diffractive optical element is disposed in the transmission path of the optical signal. The transmissive diffractive optical element can achieve the same technical effect as the reflective diffractive optical element, and the working principle is the same, so it will not be described again here.

[0092] In some embodiments, the photonic integrated chip 1 provided in this application can be a co-package optoelectronic (CPO) structure that includes an electronic integrated circuit (EIC). Since the interface of the dispersion compensation structure 13 for interacting with optical signals is located inside the cover layer 10, contamination that may occur during the back-end packaging process of the electronic integrated circuit due to molding, reflow soldering, and other processes will not directly affect the functional part of the dispersion compensation structure 13, thereby achieving a certain degree of anti-contamination capability.

[0093] This application also provides a communication device, which may include the photonic integrated chip 1 and the coupling element 7 in the above embodiments. The coupling element 7 may be a component for transmitting optical signals, such as an optical fiber, prism, or waveguide. The coupling element 7 is coupled in the optical port area 8 of the photonic integrated chip 1 and is used to transmit optical signals through the optical port area 8.

[0094] For example, the communication device can be an optical module, switch, server, or other device that exchanges information via optical signals, and the photonic integrated chip 1 can realize functions such as transmitting and receiving optical signals in the communication device.

[0095] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations 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. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A photonic integrated chip, characterized in that, The photonic integrated chip includes a waveguide layer and a cover plate layer located on one side of the waveguide layer, wherein the outer surface of the cover plate layer away from the waveguide layer includes an optical port region; A grating coupler is provided in the waveguide layer, and the grating coupler is used to transmit optical signals to the cover plate layer; The cover plate layer is provided with a dispersion compensation structure, which is used to transmit the optical signal emitted from the grating coupler to the optical port area; the dispersion compensation structure includes a diffractive optical element, which is used to compress the dispersion angle between optical signals of different wavelengths.

2. The photonic integrated chip according to claim 1, characterized in that, The dispersion compensation structure includes a first reflective element and a second reflective element disposed opposite to each other in a direction perpendicular to the waveguide layer. The first reflective element and the second reflective element are used to transmit the optical signal emitted from the grating coupler to the optical port area after at least two reflections. At least one of the first reflective element and the second reflective element is the diffractive optical element, and the diffractive optical element is a reflective diffractive optical element.

3. The photonic integrated chip according to claim 2, characterized in that, The first reflective element is the reflective diffractive optical element, and the second reflective element is a metal reflective layer or a Bragg reflective layer.

4. The photonic integrated chip according to claim 3, characterized in that, The first reflective element includes a first functional portion and a second functional portion arranged at intervals. The first functional portion is used to reflect the optical signal emitted from the grating coupler to the second reflective element, and the second functional portion is used to reflect the optical signal emitted from the second reflective element to the second reflective element. The second reflective element is used to reflect the optical signal emitted from the first functional portion to the second functional portion, and also to reflect the optical signal reflected from the second functional portion to the optical port area.

5. The photonic integrated chip according to any one of claims 2 to 4, characterized in that, The first reflective element is disposed at the top of the cover plate layer away from the waveguide layer, and the second reflective element is disposed at the bottom of the cover plate layer near the waveguide layer or disposed in the cover plate layer.

6. The photonic integrated chip according to claim 5, characterized in that, The cover plate layer includes an upper cladding layer and a dielectric layer. The upper cladding layer is disposed on one side of the waveguide layer, and the dielectric layer is disposed on the side of the upper cladding layer away from the waveguide layer and covers a portion of the upper cladding layer. The second reflective element is disposed on the upper cladding near the bottom of the waveguide layer or on the dielectric layer near the bottom of the upper cladding.

7. The photonic integrated chip according to claim 5, characterized in that, The cover plate layer includes an upper cladding layer and a dielectric layer. The upper cladding layer is disposed on one side of the waveguide layer, and the dielectric layer is disposed on the side of the upper cladding layer away from the waveguide layer. The upper cladding layer and the dielectric layer are made of different materials. The second reflective element is disposed on the upper cladding near the bottom of the waveguide layer or on the dielectric layer near the bottom of the upper cladding.

8. The photonic integrated chip according to any one of claims 2 to 7, characterized in that, The reflective diffractive optical element includes a microstructure layer, a reflective Bragg grating, or a freeform surface.

9. The photonic integrated chip according to claim 8, characterized in that, The reflective diffractive optical element includes the microstructure layer and a reflective film, wherein the reflective film is disposed on the side of the microstructure layer away from the waveguide layer.

10. The photonic integrated chip according to claim 1, characterized in that, The diffractive optical element is a transmission type diffractive optical element, and it is disposed in the transmission path of the optical signal in the cover plate layer.

11. The photonic integrated chip according to any one of claims 1 to 10, characterized in that, The diffractive optical element is also used to shape the optical signal.

12. The photonic integrated chip according to any one of claims 1 to 11, characterized in that, The photonic integrated chip includes an antireflective coating disposed on the outside of the optical port area.

13. The photonic integrated chip according to any one of claims 1 to 12, characterized in that, The dispersion compensation structure also includes a microlens disposed in the optical port region of the cover plate layer, and the microlens is used to perform speckle shaping on the optical signal.

14. The photonic integrated chip according to any one of claims 1 to 13, characterized in that, The thickness of the cover layer is greater than 100 micrometers in the direction perpendicular to the waveguide layer.

15. The photonic integrated chip according to any one of claims 1 to 14, characterized in that, The photonic integrated chip is an optoelectronic co-packaged structure that includes electronic integrated circuits.

16. A communication device, characterized in that, The communication device includes: The photonic integrated chip as described in any one of claims 1 to 15; and A coupling element is coupled to the optical port area of ​​the photonic integrated chip for transmitting optical signals through the optical port area.

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