Optical transmitting assembly, optical receiving assembly and optical module

Abstract

The invention discloses an optical transmitting assembly, an optical receiving assembly and an optical module.The optical transmitting assembly comprises a laser, a first optical chip, a second spot-size converter and a first optical fiber, the first optical chip comprises an optical multiplexer and a spot-size converter, the laser is used for generating laser, the optical multiplexer is used for multiplexing the laser, and the spot-size converter is used for converting the laser into the first optical fiber; the first spot-size converter is used for amplifying the spot-size of the emergent light of the optical multiplexer, and the second spot-size converter is used for amplifying the spot-size of the emergent light of the first spot-size converter. According to the optical transmitting assembly, the optical receiving assembly and the optical module, spot-size conversion is carried out through the two spot-size converters on the optical chip and outside the optical chip respectively, so that the requirement for the overall coupling capacity of the spot-size converters on the chip is reduced; the size of the spot size can be properly adjusted while the on-chip spot size converter only needs to have high coupling efficiency for different polarization states, so that polarization dependent loss can be avoided while the coupling efficiency is met.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, specifically relating to an optical transmitting component, an optical receiving component, and an optical module. Background Technology

[0002] In the optical transmission components of optical modules, a PBRC (Polarization Rotation Combiner) is often introduced on the optical chip to perform first-level multiplexing, which introduces different polarization states. When coupling the optical fiber to the mode converter (usually implemented using an edge coupler) on the optical chip, due to the large mode size of the fiber, the mode converter often struggles to ensure that modes of different polarization states have the same shape and size while maintaining overall coupling efficiency. It also cannot guarantee that different polarization states will have the same or similar coupling efficiency. When the input light has different polarization states, the difference in coupling efficiency between these states introduces polarization-dependent loss, causing channel imbalance.

[0003] Meanwhile, for optical chips used as optical receivers, the signals they receive originate from long-distance fiber optic transmission and have random polarization states. Similarly, when coupled and converted by an on-chip mode converter, polarization-dependent losses are introduced, causing signal imbalances between channels and in the time domain. These problems need to be avoided in the product.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide an optical transmitting component, an optical receiving component, and an optical module that can solve the problem that coupling efficiency and polarization-dependent loss cannot be simultaneously satisfied during the coupling process between optical chips and optical fibers.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] An optical transmitting component includes a laser, a first optical chip, and a first optical fiber. The first optical chip includes an optical multiplexer. The laser is used to generate laser light, and the optical multiplexer is used to multiplex the laser light. The first optical chip also includes a first mode converter. A second mode converter is disposed between the first optical chip and the first optical fiber. The first mode converter is used to amplify the mode of the light emitted from the optical multiplexer, and the second mode converter is used to amplify the mode of the light emitted from the first mode converter.

[0008] In one or more embodiments of the present invention, for the outgoing light of the optical multiplexer, the difference in conversion efficiency between the first mode converter for the TE mode and the TM mode is less than or equal to 10%; and / or

[0009] For the output light of the first mode converter, the ellipticity of its TE mode mode and the ellipticity of its TM mode mode are less than or equal to 1.5; and / or

[0010] For the output light of the first mode converter, the difference in diameter between the TE mode pattern and the TM mode pattern is less than or equal to 1.5. .

[0011] In one or more embodiments of the present invention, the first mode converter includes a first cladding and a first waveguide disposed within the first cladding and extending along a first direction. The width of the first waveguide gradually decreases along the first direction and the height is equal. The end face of the first waveguide near the second mode converter is a circle or a regular polygon with an even number of sides.

[0012] In one or more embodiments of the present invention, the end face of the first waveguide near the first mode converter is square; and / or

[0013] The width and height of the first cladding layer are equal.

[0014] In one or more embodiments of the present invention, the first mode converter includes a first cladding and a plurality of second waveguides disposed within the first cladding and extending along a first direction.

[0015] In one or more embodiments of the present invention, the second mode converter includes a first lens having positive optical power.

[0016] In one or more embodiments of the present invention, the optical transmitting component further includes a first optical isolator, wherein the second mode converter and the first optical isolator are sequentially disposed between the first optical chip and the first optical fiber; and / or

[0017] The optical transmission component further includes at least one first optical isolator, and a plurality of second mode converters are provided between the first optical chip and the first optical fiber, with the first optical isolator disposed between adjacent second mode converters.

[0018] A specific embodiment of the present invention also provides an optical receiving component, the optical receiving component including a second optical chip and a second optical fiber, the second optical chip including a photoelectric converter, the second optical chip further including a third mode converter, a fourth mode converter being provided between the second optical chip and the second optical fiber, the fourth mode converter being used to reduce the mode of the emitted light from the second optical fiber, the third mode converter being used to reduce the mode of the emitted light from the fourth mode converter, and the photoelectric converter being used to perform photoelectric conversion on the emitted light from the third mode converter.

[0019] In one or more embodiments of the present invention, when both the TE mode mode spot and the TM mode mode spot of the emitted light from the fourth mode converter are circular, the difference in conversion efficiency between the TE mode and the TM mode by the third mode converter is less than or equal to 5%; and / or

[0020] For the output light of the fourth mode converter, when the diameter of the TE mode spot and the diameter of the TM mode spot are the same, the difference in conversion efficiency between the TE mode and the TM mode of the third mode converter is less than or equal to 10%.

[0021] In one or more embodiments of the present invention, the third mode converter includes a second cladding and a third waveguide disposed within the second cladding and extending along a second direction. The width of the third waveguide gradually decreases along the second direction and the height is equal. The end face of the third waveguide near the fourth mode converter is circular or a regular polygon with an even number of sides.

[0022] In one or more embodiments of the present invention, the end face of the third waveguide near the fourth mode converter is square; and / or

[0023] The width and height of the second cladding layer are equal.

[0024] In one or more embodiments of the present invention, the third mode converter includes a second cladding and a plurality of fourth waveguides disposed within the second cladding and extending along a second direction.

[0025] In one or more embodiments of the present invention, the fourth mode converter includes a second lens having positive optical power.

[0026] In one or more embodiments of the present invention, the optical receiving component further includes a second optical isolator, and the fourth mode converter and the second optical isolator are sequentially disposed between the second optical chip and the second optical fiber; and / or

[0027] The optical receiving component further includes at least one second optical isolator, and a plurality of fourth mode converters are provided between the second optical chip and the second optical fiber, with the second optical isolator disposed between adjacent fourth mode converters.

[0028] A specific embodiment of the present invention also provides an optical module, including the above-described optical transmitting component or the above-described optical receiving component.

[0029] Compared with the prior art, which only uses an on-chip mode converter for one mode conversion, the optical transmitting component, optical receiving component and optical module of the present invention use two mode converters, one on the optical chip and one outside the optical chip, to perform mode conversion separately. This reduces the overall coupling capability requirement of the on-chip mode converter, so that the on-chip mode converter only needs to have high coupling efficiency for different polarization states and can appropriately adjust the size of the mode. This can avoid polarization-related losses while meeting the coupling efficiency requirements, and greatly reduce the design difficulty of the on-chip mode converter. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a mode spot converter on an optical chip in the prior art.

[0032] Figure 2 This is a schematic diagram of the structure of an optical transmitting component in one embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of mode conversion of an optical transmitting component in one embodiment of the present invention.

[0034] Figure 4 This is a three-view drawing of the first pattern converter in one embodiment of the present invention.

[0035] Figure 5 This is a three-view drawing of the first pattern converter in another embodiment of the present invention.

[0036] Figure 6 This is a three-view drawing of the first pattern converter in another embodiment of the present invention.

[0037] Figure 7 This is a partial structural diagram of an optical transmitting component in one embodiment of the present invention.

[0038] Figure 8This is a partial structural schematic diagram of the optical transmitting component in another embodiment of the present invention.

[0039] Figure 9 This is a schematic diagram of the structure of an optical receiving component in one embodiment of the present invention.

[0040] Figure 10 This is a schematic diagram of mode conversion of the optical receiving component in one embodiment of the present invention.

[0041] Figure 11 This is a three-view drawing of the third mode converter in one embodiment of the present invention.

[0042] Figure 12 This is a three-view drawing of the third pattern converter in another embodiment of the present invention.

[0043] Figure 13 This is a three-view drawing of the third pattern converter in another embodiment of the present invention.

[0044] Figure 14 This is a partial structural diagram of an optical receiving component in one embodiment of the present invention.

[0045] Figure 15 This is a partial structural schematic diagram of the optical receiving component in another embodiment of the present invention. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0047] The terms "coupled," "connected," or "linked" in the specification include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as an electrical conduction medium, which may have parasitic inductance or capacitance. Indirect connections may also include connections made through other active or passive devices to achieve the same or similar functional purpose, such as connections through switches, follower circuits, or other circuits or components. Furthermore, in the invention, terms such as "first" and "second" are primarily used to distinguish one technical feature from another, and do not necessarily require or imply any actual relationship, quantity, or order between these technical features.

[0048] In the detailed description of this specification, reference is made to the accompanying drawings, which form a part thereof, wherein like reference numerals always denote like parts, and wherein exemplary embodiments are shown by way of example that may be implemented. It should be understood that other embodiments may be utilized, and structural or logical changes may be made, without departing from the scope of this application. Therefore, the following detailed description should not be considered limiting.

[0049] The various operations in the specification may be described sequentially as multiple discrete actions or operations in a manner most conducive to understanding the claimed subject matter. However, the order of description should not be construed as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. Various additional operations may be performed in additional embodiments and / or the described operations may be omitted.

[0050] For the purposes of this application, the phrase "A and / or B" means (A), (B), or (A and B). For the purposes of this application, the phrase "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0051] Various components and devices may be mentioned or shown in the singular form herein, but only for the convenience of discussion, and any element mentioned in the singular form may include multiple such elements as taught herein.

[0052] The description uses the phrases "in one embodiment," "in other embodiments," or "in some embodiments," each of which can refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," etc., used in relation to embodiments of this application are synonymous.

[0053] In existing technologies, the main approach to minimize the impact of polarization-dependent losses is to achieve balance by sacrificing the performance of better polarization states. Generally, mode-mode converters (MTBs) achieve better performance in the TE polarization state, while the TM polarization state performs worse, typically by about 0.8 dB. Current design approaches generally sacrifice the coupling efficiency of the TE mode to achieve balance with the TM mode, but this sacrifices the performance of the optical module.

[0054] exist Figure 1The diagram illustrates a design scheme in the prior art. This mode converter includes a cladding 10' and one (or more) inverted taper waveguides 20' disposed within the cladding 10'. Near the right side of the fiber, the heights H1' of the cladding 10' and H2' of the waveguide 20' are often determined by the SOI wafer or fab process and cannot be arbitrarily changed. To match the emitted light mode field as closely as possible to the fiber mode field, under current process conditions, only the width W2' of the waveguide 20' can be compressed; the width W1' of the cladding 10' is typically extended indefinitely, and the dimensions at the end of the waveguide 20' cannot be arbitrarily modified. Typically, the typical values ​​for these dimensions are W2' = 100 nm ~ 150 nm, H1' = 300 nm ~ 400 nm, and W1' = 100 nm ~ 150 nm. 9 H1'=6 ~9 Furthermore, the center of waveguide 20' may be offset relative to the center of cladding 10'. Under such characteristic dimensions, the output spot of the mode converter is typically an elliptical spot, making it difficult to obtain a circular spot. Since the optical fiber spot is circular, this leads to mode field mismatch. Additionally, because the electric field vibration directions of the TE and TM modes are different, even with the same structure, the mode spots of two different polarization states will exhibit different behaviors. For example, the mode field of an optical fiber is typically 9.6 mm in diameter. The perfect circle, while the terminal optical field of the mode converter is perpendicular to the TE mode along the vertical axis 9. Horizontal axis 7 The ellipse, with TM modulus as 6 on the vertical axis Horizontal axis 8 The waveguide pattern is elliptical. This indicates a difference in coupling performance, meaning there is polarization-dependent loss. Furthermore, in CMOS technology, the waveguide 20' pattern can only be designed in a planar dimension. The TE and TM modes also exhibit different losses during transmission, exacerbating polarization-dependent loss. Therefore, designing a mode-spot coupler that achieves high coupling efficiency in both the TE and TM modes while ensuring that the mode spots of both polarization states are similar in size and circular in shape is extremely difficult.

[0055] Example 1

[0056] like Figure 2 As shown, in one embodiment of the present invention, the optical transmission component includes a laser 11, a first optical chip 20 and a first optical fiber 12. The first optical chip 20 includes an optical multiplexer 21 and a first mode converter 22.

[0057] Among them, laser 11 is used to generate laser light, optical multiplexer 21 is used to multiplex laser light, and a second mode converter 13 is provided between the first optical chip 20 and the first optical fiber 12. The first mode converter 22 is used to amplify the mode of the light emitted from the optical multiplexer 21, and the second mode converter 13 is used to amplify the mode of the light emitted from the first mode converter 22.

[0058] Since the optical multiplexer 21 includes polarization multiplexing functionality, it may introduce multiple polarization states, leading to polarization-related loss problems. Figure 3 The diagram illustrates the amplification effect of the first mode converter 22 and the second mode converter 13 on the mode spot. It can be seen that the first mode converter 22 on the optical chip and the second mode converter 13 outside the optical chip amplify the mode spot of the output light of the optical multiplexer 21, respectively. This reduces the requirement for the mode spot amplification capability of the first mode converter 22, so that the first mode converter 22 only needs to have high conversion efficiency for different polarization states and can appropriately adjust the size of the mode spot. This can avoid polarization-related losses while meeting the overall coupling efficiency between the first optical chip 20 and the first optical fiber 12, and greatly reduce the design difficulty of the first mode converter 22.

[0059] In one embodiment, the second mode converter 13 includes a first lens having positive optical power.

[0060] The mode spot converted by the first mode spot converter 22 is often too small after it exits the optical chip, making it difficult to meet the requirement of direct coupling into the first optical fiber 12. By reasonably setting the focal length and position of the first lens, the size of the mode spot can be easily adjusted. When the mode spot is magnified twice by the first lens in free space, a mode field matching the first optical fiber 12 can be obtained.

[0061] Furthermore, the first lens can be a GRIN lens (gradient refractive index lens). This type of lens controls the light propagation path by continuously changing the refractive index inside the material (rather than relying on the surface curvature), and has the advantages of flexible structural design, small size, and high integration convenience.

[0062] like Figure 2 As shown, in one embodiment, the optical transmitting component further includes a third lens 14, and the first optical chip 20 further includes an edge coupler 24 and an optical modulator 23. The laser 11, the third lens 14, the edge coupler 24, the optical modulator 23, and the optical multiplexer 21 are coupled sequentially. The third lens 14 and the edge coupler 24 are used to couple the laser light generated by the laser 11 to the optical modulator 23, and the optical modulator 23 is used to modulate the laser light.

[0063] In one embodiment, multiple lasers 11 are provided, and multiple sets of optical modulators 23, edge couplers 24 and optical modulators 23 can be provided corresponding to the lasers 11. The optical multiplexer 21 multiplexes the lasers generated by the multiple lasers 11.

[0064] In other embodiments, the laser 11, the edge coupler 24, and the optical modulator 23 can also be provided as one. The first optical chip 20 can also include a beam splitter disposed between the edge coupler 24 and the optical modulator 23. The beam splitter is used to split the laser beam. Multiple optical modulators 23 can be provided to correspond to the split laser beam. The optical multiplexer 21 multiplexes the split laser beam.

[0065] Preferably, for the output light of the optical multiplexer 21, the difference in conversion efficiency between the TE mode and the TM mode by the first mode converter 22 is less than or equal to 10%. By approximating the conversion efficiency of different polarization states, polarization-dependent losses can be largely avoided. More preferably, the difference in conversion efficiency between the TE mode and the TM mode by the first mode converter 22 is less than or equal to 5%. It is understood that for the output light of the optical multiplexer 21, the effect is best when the conversion efficiency of its first mode converter 22 for the TE mode and the TM mode is equal.

[0066] Preferably, for the output light of the first mode converter 22, the ellipticity of both the TE mode mode spot and the TM mode mode spot is less than or equal to 1.5. Ellipticity is the ratio of the maximum diameter to the minimum diameter of the mode spot. By ensuring that mode spots of different polarization states can approach perfect circularity, mode field mismatch is avoided during the input of the mode spots to the first optical fiber 12. More preferably, the ellipticity of both the TE mode mode spot and the TM mode mode spot is less than or equal to 1.3. It is understood that the best effect is achieved when the ellipticity of both the TE mode mode spot and the TM mode mode spot of the output light of the first mode converter 22 is 1.

[0067] Preferably, for the output light of the first mode converter 22, the difference in diameter between the TE mode and the TM mode is less than or equal to 1.5 μm. By ensuring that the mode sizes of different polarization states are close, a closer coupling efficiency can also be obtained. It should be noted that for elliptical or other non-circular modes, either the maximum diameter or the minimum diameter should be taken simultaneously, or the effective diameter should be calculated by inversely estimating the effective area. Understandably, for the output light of the first mode converter 22, the best effect is achieved when the diameters of the TE mode and the TM mode are equal.

[0068] Figure 4The diagram shows a front view, side view, and top view of a first mode converter 22 in a specific embodiment (the front view is at the upper left of the drawing, the side view is to the right of the front view, and the top view is below the front view). Specifically, the first mode converter 22 includes a first cladding 221 and a first waveguide 222 disposed within the first cladding 221 and extending along a first direction. The width W2 of the first waveguide 222 gradually decreases along the first direction, while its height H2 remains constant. The end face of the first waveguide 222 near the second mode converter 13 is either circular or a regular polygon with an even number of sides.

[0069] Under this structure, it is easy to make the difference in conversion efficiency between the first mode converter 22 for the TE mode and the TM mode smaller, while making the ellipticity of the TE mode mode spot and the TM mode mode spot of the emitted light smaller and closer to a perfect circle, and ensuring that the difference in diameter between the TE mode mode spot and the TM mode mode spot is small and close to equal.

[0070] For example, the first direction is the direction in which the optical multiplexer 21 points to the second mode converter 13.

[0071] Preferably, the end face of the first waveguide 222 near the first mode converter 22 is square. In actual design, since the height of the first waveguide 222 is often determined by the SOI wafer or fab process and cannot be arbitrarily changed, the width W2 of the first waveguide 222 can be set as its height value H2.

[0072] Preferably, the width W1 of the first cladding layer 221 is equal to its height H1, which is beneficial for forming a circular pattern. In actual design, since the height H1 of the first cladding layer 221 is often determined by the SOI wafer process and cannot be arbitrarily changed, the width W1 of the first cladding layer 221 can be set as its height value H1.

[0073] Preferably, there is a gap between the end of the first waveguide 222 near the second mode converter 13 and the end of the first cladding 221 near the second mode converter 13, which is conducive to mode expansion.

[0074] The shape and size of the first waveguide 222 and the first cladding 221 near the end of the optical multiplexer 21 are generally determined by the output waveguide of the optical multiplexer 21 and can be designed according to actual needs.

[0075] Figure 5 and Figure 6The diagram shows a front view, side view, and top view of the first mode converter 22 in other specific embodiments (the front view is at the upper left of the drawing, the side view is to the right of the front view, and the top view is below the front view). Specifically, the first mode converter 22 may also include a first cladding 221 and a plurality of second waveguides disposed within the first cladding 221 and extending along a first direction. A single waveguide is typically large in size due to material thickness limitations, while multiple waveguides can reduce the size of each waveguide to a smaller size, facilitating mode expansion; at the same time, it increases the variable of the spacing between waveguides, introducing more variables into the waveguide design, making it easier to achieve improved and balanced coupling efficiency between TE and TM modes.

[0076] For example, the first direction is the direction in which the optical multiplexer 21 points to the second mode converter 13.

[0077] In such Figure 5 In one specific embodiment shown, three second waveguides are provided, namely second waveguide 223, second waveguide 224, and second waveguide 225. Second waveguide 223 is located near one end of the optical multiplexer 21, and second waveguide 224 and second waveguide 225 are respectively arranged on both sides of second waveguide 223 along the width direction of second waveguide 223, so that light incident through second waveguide 223 can be coupled to second waveguide 224 and second waveguide 225.

[0078] Furthermore, the second waveguide 223 may include a straight waveguide segment and an inverted conical segment connected along the first direction, the second waveguide 224 may include a positive conical segment and an inverted conical segment connected along the first direction, and the second waveguide 225 may include a positive conical segment and an inverted conical segment connected along the first direction. The positive conical segment of the second waveguide 224 and the positive conical segment of the second waveguide 225 are located on both sides of the inverted conical segment of the second waveguide 223, respectively.

[0079] The second waveguide 223, the second waveguide 224, and the second waveguide 225 can have the same height H4, and their bottom surfaces are all located on the same plane.

[0080] In such Figure 6 In another specific embodiment shown, three second waveguides are provided, namely second waveguide 226, second waveguide 227, and second waveguide 228. Second waveguide 226 is located near one end of the optical multiplexer 21. Second waveguide 227 and second waveguide 228 are arranged sequentially along the width direction of second waveguide 226 and connected to the end of second waveguide 226 near the second mode converter 13, so that light incident through second waveguide 226 can be coupled to second waveguide 227 and second waveguide 228.

[0081] Furthermore, the second waveguide 226 may include a straight waveguide segment and a positive conical segment connected along the first direction, and the second waveguide 227 and the second waveguide 228 each include an inverted conical segment.

[0082] For the aforementioned first mode converter 22 structure with multiple second waveguides, those skilled in the art can achieve any one or more of the following technical effects through reasonable structural parameter design: "For the output light of the optical multiplexer 21, the difference in conversion efficiency between the TE mode and the TM mode of the first mode converter 22 is less than or equal to 10%", "For the output light of the first mode converter 22, the ellipticity of both the TE mode and the TM mode is less than or equal to 1.5", and "For the output light of the first mode converter 22, the difference in diameter between the TE mode and the TM mode is less than or equal to 1.5 μm". For example, at the end near the second mode converter 13, the diameter of the TE mode and the TM mode can be adjusted by adjusting the spacing between the multiple second waveguides; increasing the width W4 of the second waveguides helps to reduce the ellipticity of the TE mode and the TM mode; adopting an axisymmetric or centrosymmetric design for the multiple second waveguides helps to reduce the difference in conversion efficiency between the TE mode and the TM mode, and so on.

[0083] Of course, the first mode converter 22 can also adopt other specific design structures.

[0084] like Figure 7 As shown, in one embodiment, the optical transmitting component may further include a first optical isolator 15, with the second mode converter 13 and the first optical isolator 15 sequentially disposed between the first optical chip 20 and the first optical fiber 12. The first optical isolator 15 can isolate reverse light.

[0085] like Figure 8 As shown, in another embodiment, the optical transmitting component may also include at least one first optical isolator 15, and a plurality of second mode converters 13 are provided between the first optical chip 20 and the first optical fiber 12, with the first optical isolator 15 disposed between adjacent second mode converters 13. By reasonably setting the position and parameters of the second mode converters 13, the two sides of the first optical isolator 15 can be made to be nearly parallel light, which is beneficial to the operation of the first optical isolator 15.

[0086] Example 2

[0087] like Figure 9 As shown, in one embodiment of the present invention, the optical receiving component includes a second optical chip 40 and a second optical fiber 31. The second optical chip 40 includes a photoelectric converter 41 and a third mode converter 42. A fourth mode converter 32 is provided between the second optical chip 40 and the second optical fiber 31.

[0088] The fourth mode converter 32 is used to reduce the mode of the emitted light from the second optical fiber 31, the third mode converter 42 is used to reduce the mode of the emitted light from the fourth mode converter 32, and the photoelectric converter 41 is used to perform photoelectric conversion on the emitted light from the third mode converter 42.

[0089] Since the external optical signal becomes a mixed polarization state after being transmitted through the second optical fiber 31, it also leads to polarization-dependent loss. Figure 10 The diagram illustrates the mode reduction effect of the fourth mode converter 32 and the third mode converter 42. It can be seen that the mode reduction of the output light from the second optical fiber 31 is achieved by the fourth mode converter 32 outside the optical chip and the third mode converter 42 on the optical chip, respectively. This reduces the requirement for the mode reduction capability of the third mode converter 42, allowing it to have high conversion efficiency for different polarization states while appropriately adjusting the mode size. This ensures that the overall coupling efficiency between the second optical fiber 31 and the second optical chip 40 is met while avoiding polarization-related losses, greatly reducing the design difficulty of the third mode converter 42.

[0090] In one embodiment, the fourth mode converter 32 includes a second lens having positive optical power.

[0091] To ensure similar conversion efficiency for different polarization states, the third mode converter 42 often cannot couple larger mode spots to the photoelectric converter 41 with high efficiency. By properly setting the focal length and position of the second lens, the size of the mode spot can be easily adjusted. After the mode spot is initially reduced by the second lens, it becomes easier for the third mode converter 42 to convert it with high efficiency.

[0092] In one embodiment, the second lens can be a GRIN lens (gradient refractive index lens). This type of lens controls the light propagation path by continuously changing the refractive index inside the material (rather than relying on the surface curvature), and has the advantages of flexible structural design, small size, and high integration convenience.

[0093] Preferably, for the emitted light of the fourth mode converter 32, when both its TE mode and TM mode modes are circular, the difference in conversion efficiency between the TE mode and TM mode by the third mode converter 42 is less than or equal to 5%. More preferably, the difference in conversion efficiency between the TE mode and TM mode by the third mode converter 42 is less than or equal to 1%. It is understood that for the emitted light of the fourth mode converter 32, when both its TE mode and TM mode modes are circular, the effect is best when the conversion efficiency of the third mode converter 42 for the TE mode and TM mode is equal.

[0094] Preferably, for the emitted light of the fourth mode converter 32, when the diameters of the TE mode spot and the TM mode spot are the same, the difference in conversion efficiency between the TE mode and the TM mode by the third mode converter 42 is less than or equal to 10%. More preferably, the difference in conversion efficiency between the TE mode and the TM mode by the third mode converter 42 is less than or equal to 5%. It is understood that for the emitted light of the fourth mode converter 32, when the diameters of the TE mode spot and the TM mode spot are the same, the effect is best when the conversion efficiency of the third mode converter 42 for the TE mode and the TM mode is equal.

[0095] Since TE and TM modes in optical fibers typically have circular mode spots of the same size, the output light of the fourth mode spot converter 32 also typically has TE and TM mode spots of the same size and circular shape. If the conversion efficiency of the third mode spot converter 42 for TE and TM modes is equal or close, polarization loss can be avoided.

[0096] Figure 11 The diagram shows a front view, side view, and top view of the third mode converter 42 in a specific embodiment (the front view is at the upper left of the drawing, the side view is to the right of the front view, and the top view is below the front view). Specifically, the third mode converter 42 includes a second cladding 421 and a third waveguide 422 disposed within the second cladding 421 and extending along a second direction. The width W6 of the third waveguide 422 gradually decreases along the second direction, while its height H6 remains constant. The end face of the third waveguide 422 near the fourth mode converter 32 is either circular or a regular polygon with an even number of sides.

[0097] For example, the second direction is the direction in which the photoelectric converter 41 points to the fourth mode converter 32.

[0098] Understandably, due to the reversibility of the optical path, under this structure, the conversion efficiency of the light to the TE mode and the TM mode can be nearly the same regardless of whether the light is incident in the forward or backward direction. Therefore, when the third mode converter 42 couples the output light of the fourth mode converter 32 to the photoelectric converter 41, polarization-dependent loss can also be avoided.

[0099] Preferably, the end face of the third waveguide 422 near the fourth mode converter 32 is square. In actual design, since the height H6 of the third waveguide 422 is often determined by the SOI wafer or fab process and cannot be arbitrarily changed, the width W6 of the third waveguide 422 can be set as its height value H6.

[0100] Preferably, the width W5 of the second cladding layer 421 is equal to its height H5, which is beneficial for forming a circular pattern. In actual design, since the height H5 of the second cladding layer 421 is often determined by the SOI wafer process and cannot be arbitrarily changed, the width W5 of the second cladding layer 421 can be set to its height value H5.

[0101] Preferably, there is a gap between the end of the third waveguide 422 near the fourth mode converter 32 and the end of the second cladding 421 near the fourth mode converter 32, which is beneficial for mode constraint.

[0102] The shape and size of the third waveguide 422 and the second cladding 421 near the end of the photoelectric converter 41 are generally determined by the input waveguide of the photoelectric converter 41 and can be designed according to actual needs.

[0103] Figure 12 and Figure 13 The diagram shows a front view, side view, and top view of the third mode converter 42 in other specific embodiments (the front view is at the upper left of the drawing, the side view is to the right of the front view, and the top view is below the front view). Specifically, the third mode converter 42 may also include a second cladding 421 and a plurality of fourth waveguides disposed within the second cladding 421 and extending along a second direction. A single waveguide is typically large in size due to material thickness limitations, while multiple waveguides can reduce the size of each waveguide to a smaller size, facilitating mode expansion; simultaneously, it increases the variable of the spacing between waveguides, introducing more variables into waveguide design, making it easier to achieve improved and balanced coupling efficiency between TE and TM modes.

[0104] For example, the second direction is the direction in which the photoelectric converter 41 points to the fourth mode converter 32.

[0105] In such Figure 12 In one specific embodiment shown, three fourth waveguides are provided, namely fourth waveguide 423, fourth waveguide 424, and fourth waveguide 425. Fourth waveguide 423 is disposed near one end of the photoelectric converter 41, and fourth waveguide 424 and fourth waveguide 425 are respectively disposed on both sides of fourth waveguide 423 along the width direction of fourth waveguide 423, so that light incident through fourth waveguide 424 and fourth waveguide 425 can be coupled to fourth waveguide 423.

[0106] Furthermore, the fourth waveguide 423 may include a straight waveguide segment and an inverted conical segment connected along the second direction, the fourth waveguide 424 may include a positive conical segment and an inverted conical segment connected along the second direction, and the fourth waveguide 425 may include a positive conical segment and an inverted conical segment connected along the second direction. The positive conical segments of the fourth waveguide 424 and the fourth waveguide 425 are located on both sides of the inverted conical segment of the fourth waveguide 423, respectively.

[0107] The fourth waveguide 423, the fourth waveguide 424 and the fourth waveguide 425 can have the same height and their bottom surfaces are all located on the same plane.

[0108] In such Figure 13 In another specific embodiment shown, three fourth waveguides are provided, namely fourth waveguide 426, fourth waveguide 427, and fourth waveguide 428. Fourth waveguide 426 is disposed near one end of photoelectric converter 41. Fourth waveguide 427 and fourth waveguide 428 are arranged sequentially along the width of fourth waveguide 426 and connected to the end of fourth waveguide 426 near the second mode converter 13, so that light incident through fourth waveguide 427 and fourth waveguide 428 can be coupled to fourth waveguide 426.

[0109] Furthermore, the fourth waveguide 426 may include a straight waveguide segment and a positive conical segment connected along the second direction, and the fourth waveguide 427 and the fourth waveguide 428 each include an inverted conical segment.

[0110] For the aforementioned third-mode converter 42 structure with multiple second waveguides, those skilled in the art can design reasonable structural parameters to achieve the same or similar conversion efficiency for TE and TM modes. Specific design principles can be found in the relevant description in Embodiment 1, and will not be elaborated upon here.

[0111] Of course, the third mode converter 42 can also adopt other specific design structures.

[0112] like Figure 14 As shown, in one embodiment, the optical transmitting component may further include a second optical isolator 33, with the fourth mode converter 32 and the second optical isolator 33 sequentially disposed between the second optical chip 40 and the second optical fiber 31. The second optical isolator 33 can isolate reflected light.

[0113] like Figure 15 As shown, in another embodiment, the optical transmitting component may also include at least one second optical isolator 33, and a plurality of fourth mode converters 32 are provided between the second optical chip 40 and the second optical fiber 31, with the second optical isolator 33 disposed between adjacent fourth mode converters 32. By reasonably setting the position and parameters of the fourth mode converters 32, the two sides of the second optical isolator 33 can be made to be nearly parallel, which is beneficial to the operation of the second optical isolator 33.

[0114] Example 3

[0115] This embodiment provides an optical module, including an optical transmitting component as described in Embodiment 1 and an optical receiving component as described in Embodiment 2, or including an optical transmitting component as described in Embodiment 1, or including an optical receiving component as described in Embodiment 2.

[0116] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0117] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An optical transmitting assembly comprising a laser, a first optical chip comprising an optical multiplexer, and a first optical fiber, characterized in that, The laser is configured to generate laser light, and the optical multiplexer is configured to multiplex the laser light, the first optical chip further comprising a first mode field converter, and a second mode field converter is arranged between the first optical chip and the first optical fiber, the first mode field converter being configured to enlarge a mode field of the laser light output from the optical multiplexer, and the second mode field converter being configured to enlarge a mode field of the laser light output from the first mode field converter.

2. The optical transmitting assembly of claim 1, wherein, For the laser light output from the optical multiplexer, a difference between conversion efficiencies of TE mode and TM mode of the first mode field converter is less than or equal to 10%; and / or For the laser light output from the first mode field converter, an ellipticity of a TE mode field and an ellipticity of a TM mode field are less than or equal to 1.5; and / or the difference between the diameters of the TE mode mode spot and the TM mode mode spot of the exiting light from the first mode spot converter is less than or equal to 1.5 .

3. The optical transmitting assembly of claim 1 or 2, wherein, The first mode field converter comprises a first cladding and a first waveguide arranged in the first cladding and extending along a first direction, a width of the first waveguide gradually decreases along the first direction and a height of the first waveguide is equal, and an end face of the first waveguide close to the second mode field converter is a circle or a regular polygon with an even number of sides.

4. The optical transmitting assembly of claim 3, wherein, The end face of the first waveguide close to the first mode field converter is a square; and / or A width of the first cladding is equal to a height of the first cladding.

5. The optical transmitting assembly of claim 1 or 2, wherein, The first mode field converter comprises a first cladding and a plurality of second waveguides arranged in the first cladding and extending along a first direction.

6. The optical transmitting package of claim 1, wherein, The second mode field converter comprises a first lens having a positive focal length.

7. The optical transmitting package of claim 1, wherein, The optical transmitting assembly further comprises a first optical isolator, and the second mode field converter and the first optical isolator are arranged between the first optical chip and the first optical fiber in sequence; and / or The optical transmitting assembly further comprises at least one first optical isolator, a plurality of second mode field converters are arranged between the first optical chip and the first optical fiber, and the first optical isolator is arranged between adjacent second mode field converters.

8. An optical receiving assembly comprising a second optical chip and a second optical fiber, the second optical chip comprising an opto-electrical converter, characterized in that, The second optical chip further comprises a third mode field converter, a fourth mode field converter is arranged between the second optical chip and the second optical fiber, the fourth mode field converter is configured to reduce a mode field of the laser light output from the second optical fiber, the third mode field converter is configured to reduce a mode field of the laser light output from the fourth mode field converter, and the photoelectric converter is configured to perform photoelectric conversion on the laser light output from the third mode field converter.

9. The optical receiving assembly of claim 8, wherein, For the laser light output from the fourth mode field converter, when a TE mode field and a TM mode field are both circles, a difference between conversion efficiencies of TE mode and TM mode of the third mode field converter is less than or equal to 5%; and / or For the laser light output from the fourth mode field converter, when a diameter of the TE mode field and a diameter of the TM mode field are equal, a difference between conversion efficiencies of TE mode and TM mode of the third mode field converter is less than or equal to 10%.

10. The optical receiving assembly according to claim 8 or 9, characterized in that The third mode field converter comprises a second cladding and a third waveguide arranged in the second cladding and extending along a second direction, a width of the third waveguide gradually decreases along the second direction and a height of the third waveguide is equal, and an end face of the third waveguide close to the fourth mode field converter is a circle or a regular polygon with an even number of sides.

11. The optical receiving assembly of claim 10, wherein, The end face of the third waveguide close to the fourth mode field converter is a square; and / or A width of the second cladding is equal to a height of the second cladding. The second cladding has a width equal to a height.

12. The optical receiving assembly of claim 8 or 9, wherein, The third mode spot converter includes a second cladding and a plurality of fourth waveguides disposed within the second cladding and extending in a second direction.

13. The optical receiving assembly of claim 8, wherein, The fourth mode spot converter includes a second lens having a positive focal power.

14. The optical receiving assembly of claim 8, wherein, The light receiving assembly further includes a second optical isolator, the fourth mode spot converter and the second optical isolator are sequentially arranged between the second optical chip and the second optical fiber; and / or The light receiving assembly further includes at least one second optical isolator, a plurality of fourth mode spot converters are arranged between the second optical chip and the second optical fiber, and the second optical isolator is arranged between adjacent fourth mode spot converters.

15. An optical module characterized by comprising: An optical transmission assembly as claimed in any one of claims 1 to 7 or an optical receiving assembly as claimed in any one of claims 8 to 14.

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