An optical waveguide structure

Abstract

The utility model discloses an optical waveguide structure relates to optical communication technical field, including photon lead and the support lead of paired setting, photon lead is three -dimensional free curved surface waveguide, including the first taper waveguide, curved waveguide, second taper waveguide that connect in proper order, the first taper waveguide is away from the one end of curved waveguide and the one end of second taper waveguide away from curved waveguide connects different device end face, every support lead includes taper transition layer and stress dispersion layer of interconnection, taper transition layer is away from the one end of stress dispersion layer and connects device end face, and the one end of stress dispersion layer away from taper transition layer is connected with photon lead, and photon lead is parallel with every support lead at device end face, and the included angle that forms at the joint is greater than 45 degrees and is less than 180 degrees. Its through integral moulding design support lead and constitute stable triangle configuration on the side of photon lead, realizes the mechanical reinforcement and long -term reliable of photon lead under the premise of not sacrificing the optical performance.

Description

Technical Field

[0001] This utility model relates to the field of optical communication technology, and more specifically to an optical waveguide structure. Background Technology

[0002] In the field of optical communication, photonic wire bonding (PWB) is an advanced on-chip optical interconnect solution that is widely used for three-dimensional optical path connections between integrated photonic chips or between chips and optical fibers. Its performance directly affects the transmission efficiency and reliability of the entire optical module.

[0003] However, these three-dimensional freeform waveguide structures, directly printed using two-photon polymerization technology, typically exhibit a slender cantilever shape, resulting in inherently insufficient mechanical strength. In packaging, testing, or practical applications, when subjected to environmental stresses such as vibration, airflow, or temperature changes, the photonic leads are highly susceptible to physical positional shifts, low-frequency oscillations, or even collapse. This not only causes optical path alignment errors but can also lead to a dramatic increase in insertion loss or complete connection failure in severe cases, significantly limiting their application in industrial and commercial scenarios requiring high reliability.

[0004] In existing technologies, increasing the cross-sectional size or applying an external encapsulation layer is typically considered to enhance the stability of photonic leads. However, increasing the cross-section alters the modal characteristics of the waveguide, potentially exciting higher-order modes and disrupting single-mode transmission conditions. Furthermore, the external encapsulation material may introduce a different coefficient of thermal expansion than the photonic lead itself, generating additional stress during temperature cycling. If its refractive index is not precisely matched, it will lead to unnecessary scattering losses and end-face reflections. These methods all sacrifice optical performance for a limited improvement in mechanical strength.

[0005] Furthermore, designing a separate support structure for the photonic lead presents a series of technical challenges. First, manufacturing the support structure separately from the photonic lead presents difficulties in precise alignment, increasing process complexity. Second, improperly designed geometry at the connection point between the support structure and the photonic lead, such as sharp corners or abrupt changes in cross-section, can create significant stress concentration points, which are prone to becoming the source of structural failure during long-term use. Third, if the support structure is too close to the optical coupling region of the photonic lead, the micro-strain generated during bonding or under external forces can directly interfere with the mode field of light wave transmission, negatively impacting optical performance.

[0006] Therefore, how to design an optical waveguide structure that achieves mechanical reinforcement and long-term reliability of the photonic leads without compromising their low-loss optical transmission performance is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0007] In view of this, the present invention provides an optical waveguide structure, which aims to solve the problems of insufficient mechanical strength, susceptibility to displacement, collapse, or even breakage or detachment of existing three-dimensional photonic leads due to their slender structure. By providing a dedicated support lead integrally formed with the photonic lead and with optimized structure, the photonic lead is endowed with higher mechanical stability and resistance to environmental interference, while being fully compatible with existing fabrication processes and without affecting optical transmission performance, thus ensuring the reliability of the connection throughout its entire life cycle.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An optical waveguide structure includes photonic leads and paired support leads;

[0010] The photonic lead is a three-dimensional freeform waveguide, comprising a first tapered waveguide, a bent waveguide, and a second tapered waveguide connected in sequence; the end of the first tapered waveguide away from the bent waveguide and the end of the second tapered waveguide away from the bent waveguide are connected to different device end faces;

[0011] Each of the aforementioned support leads has an upwardly curved structure, including an interconnected tapered transition layer and a stress-dispersing layer; the end of the tapered transition layer away from the stress-dispersing layer is connected to the device end face, and the end of the stress-dispersing layer away from the tapered transition layer is connected to the photon lead.

[0012] The photonic lead and each of the support leads are parallel at the end face of the device, forming an angle greater than 45 degrees and less than 180 degrees at the connection.

[0013] Preferably, the photonic lead 1 and the support lead 2 are made of the same photocurable resin and are integrally formed by the same two-photon exposure process.

[0014] Preferably, in the support lead, the distance between the edge of the tapered transition layer and the device end face is 9 μm, and the distance between the edge of the stress dispersion layer and the photon lead and the device end face is 11 to 16 μm.

[0015] Preferably, the first tapered waveguide has a length of 16 μm, and its cross-section near the device end is elliptical with dimensions of 0.6 μm × 1.5 μm, while the cross-section near the curved waveguide end is circular with a radius of 1.1 μm.

[0016] Preferably, the curved waveguide has a length of 80 μm and is composed of multiple smoothly connected arc segments with a radius of 100 μm. The cross-sections at both ends are circular with a radius of 1.1 μm.

[0017] Preferably, the second tapered waveguide has a length of 100 μm, and its cross-section near the curved waveguide end is circular with a radius of 1.1 μm, while its cross-section near the device end is circular with a radius of 6.2 μm.

[0018] Preferably, the cross-section of the tapered transition layer near the device end is circular with a radius of 2.5 μm to 4 μm, and the cross-section of the end near the stress dispersion layer is circular with a radius of 2 μm.

[0019] Preferably, the tapered transition layer has a length of 10 μm and is an arc-shaped design with a bending radius of 20 μm.

[0020] Preferably, the stress dispersion layer has a circular cross-section with a radius of 2μm at the end near the conical transition layer, and an elliptical cross-section with a size of 2μm×0.6μm and a thickness of 2μm at the end near the photon lead.

[0021] As can be seen from the above technical solution, compared with the prior art, the present utility model has the following beneficial effects:

[0022] 1. In this structure, the support lead and the photonic lead are connected at the end face of the device to form a stable approximately triangular spatial structure, which increases the lever arm to resist external stress, thereby suppressing the photonic lead from falling over, shifting, breaking or detaching from the end face during use, and ensuring the long-term stability of the optical path connection.

[0023] 2. The support lead and the photonic lead use the same photocurable resin and are manufactured simultaneously through a two-photon exposure process, achieving seamless integration at the connection point. The consistency of materials and processes avoids optical reflection or mode field mismatch caused by heterogeneous interfaces, so that the presence of the support structure does not interfere with the normal transmission of light waves in the photonic lead.

[0024] 3. The support lead adopts a tapered transition layer with a cross-section that gradually decreases from the root to the connection point, and an arc-shaped stress dispersion layer is set at the connection with the photon lead. This can smoothly disperse external or internal stress, prevent damage to the connection point caused by stress concentration, and improve the robustness and service life of the entire support structure. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the optical waveguide structure provided in an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the photonic lead structure provided in an embodiment of this utility model;

[0028] Figure 3 A schematic diagram of the support lead structure provided in an embodiment of this utility model;

[0029] Figure 4 A schematic diagram of the loss versus wavelength curve under a supported lead wire structure provided in this embodiment of the utility model;

[0030] Figure 5 A schematic diagram of the loss versus wavelength curve under the unsupported lead wire structure provided in this embodiment of the utility model;

[0031] Figure 6 A schematic diagram illustrating the definition of distance parameters in an optical waveguide structure provided in this embodiment of the present invention;

[0032] Figure 7 A schematic diagram illustrating the effect of Z-value variation on photonic lead insertion loss in an embodiment of this utility model;

[0033] Figure 8 A schematic diagram illustrating the effect of X value variation on photonic lead insertion loss in an embodiment of this utility model;

[0034] In the figure, 1-photon lead, 2-support lead, 3-DFB laser, 4-standard single-mode fiber, 11-first tapered waveguide, 12-bent waveguide, 13-second tapered waveguide, 21-tapered transition layer, 22-stress dispersion layer. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] like Figure 1 As shown, this embodiment provides an optical waveguide structure, including photonic leads 1 and paired support leads 2;

[0037] like Figure 2As shown, the photonic lead 1 is a three-dimensional freeform waveguide, including a first tapered waveguide 11, a bent waveguide 12, and a second tapered waveguide 13 connected in sequence; the end of the first tapered waveguide 11 away from the bent waveguide 12 and the end of the second tapered waveguide 13 away from the bent waveguide 12 are connected to different device end faces.

[0038] like Figure 3 As shown, each of the supporting leads 2 has an upward arc-shaped bending structure, including a tapered transition layer 21 and a stress dispersion layer 22 connected to each other; the end of the tapered transition layer 21 away from the stress dispersion layer 22 is connected to the end face of the device, and the end of the stress dispersion layer 22 away from the tapered transition layer 21 is connected to the photon lead 1.

[0039] The photonic lead 1 and each of the support leads 2 are parallel at the end face of the device, forming an angle greater than 45 degrees and less than 180 degrees at the connection point; after the photonic lead 1 and the support lead 2 are connected, they together form a stable geometric configuration of approximately triangle in space, which enhances the mechanical stability and anti-displacement ability of the end of the photonic lead, and effectively avoids the support structure from interfering with the optical wave transmission mode field when bonding or under stress;

[0040] By integrating the support lead and the photonic lead into a stable triangular spatial configuration, it significantly enhances the mechanical stability of the photonic lead without interfering with the transmission of light waves, effectively preventing it from shifting, collapsing, or breaking during use. At the same time, its gradual stress dispersion design improves the durability of the support structure itself, thereby improving the long-term reliability of the optical waveguide structure as a whole.

[0041] The following provides a more detailed description of each component and related characteristics of the aforementioned optical waveguide structure;

[0042] In this embodiment, the photonic lead 1 and the support lead 2 are made of the same photocurable resin and are integrally formed by the same two-photon exposure process.

[0043] This optical waveguide structure is manufactured in one step using two-photon polymerization direct writing technology. By programming and controlling the three-dimensional motion trajectory of the femtosecond laser focus within the photocurable resin, the photonic lead 1, which serves as the core of optical transmission, and the support lead 2, which serves as mechanical support, can be printed simultaneously within the same processing cycle without changing processes or materials. This enables the two to achieve molecular-level cross-linking and fusion at the connection point, forming a seamless, non-adhesive monolithic structure, eliminating alignment errors and interface weaknesses caused by assembly or multiple processing steps.

[0044] Both the photonic lead 1 and the support lead 2 are made of specific photocurable resins (such as SU-8 or custom acrylates) with excellent light transmittance and mechanical stability as base materials. This ensures that the support structure not only matches the optical waveguide body in terms of mechanical properties such as thermal expansion coefficient and Young's modulus, avoiding internal stress caused by environmental changes, but also that its refractive index is consistent with that of the photonic lead (e.g., 1.5163 at a wavelength of 1550nm). This prevents the support lead from becoming an optical foreign object and introducing significant scattering or mode mismatch loss, thus ensuring the overall high performance and long-term reliability of the optical waveguide.

[0045] In this embodiment, at the connection between the tapered transition layer 21 and the device end face, the distance between the edge of the tapered transition layer 21 and the edge of the photonic lead 1 is 9 μm, and at the connection between the stress dispersion layer 22 and the photonic lead 1, the distance between the edge of the tapered transition layer 21 and the device end face is 11 to 16 μm.

[0046] In this embodiment, the first tapered waveguide 11 has a length of 16 μm, i.e., l1 = 16 μm, and its cross-section near the device end is elliptical with dimensions of 0.6 μm × 1.5 μm, i.e., r 11 =0.6μm, r 12 =1.5μm, and the cross-section near the end of the bent waveguide 12 is circular with a radius of 1.1μm, i.e., r2 = 1.1μm.

[0047] In this embodiment, the curved waveguide 12 has a length of 80 μm, i.e., l2 = 80 μm, and is composed of multiple smoothly connected circular arc segments with a radius of 100 μm. Its two ends have circular cross-sections with a radius of 1.1 μm; specifically, it is composed of four smoothly connected circular arc segments with a radius of 100 μm. a r b r c r d All are 100μm;

[0048] In this embodiment, the second tapered waveguide 13 has a length of 100 μm, i.e., l3 = 100 μm. Its cross-section near the end of the bent waveguide 12 is circular with a radius of 1.1 μm, and its cross-section near the end of the device is circular with a radius of 6.2 μm, i.e., r3 = 1.1 μm.

[0049] In this embodiment, the cross-section of the tapered transition layer 21 near the device end is circular with a radius of 2.5μm to 4μm, i.e., r'1 = 2.5-4μm, and the cross-section near the stress dispersion layer 22 end is circular with a radius of 2μm, i.e., r'2 = 2μm.

[0050] Furthermore, the conical transition layer 21 has an arc-shaped design with a length of 10 μm, i.e., l'1 = 10 μm and a bending radius of 20 μm.

[0051] In this embodiment, the stress dispersion layer 22 has a circular cross-section with a radius of 2μm at the end near the conical transition layer 21, and an elliptical cross-section with a size of 2μm × 0.6μm at the end near the photon lead 1, i.e., r' 11 =0.6μm, r' 12 =2μm, and the thickness is 2μm, that is, h = 2μm.

[0052] In this embodiment, to investigate whether the support structure affects the original transmission, FDTD numerical simulation was performed on the position of the support structure at one end of the laser. The final loss of the TE fundamental mode was used as the evaluation index, and the spatial position of the support structure was optimized. Figure 4 and Figure 5 As shown, after the addition of the support lead structure, there was no significant increase in loss due to the introduction of the support structure. The loss remained at a low level. The addition of the support structure did not have a significant negative impact on the loss performance, and the overall loss remained at a relatively good level.

[0053] Simultaneously, the influence of the position of the support point in both the X and Z directions on the loss was studied, such as... Figure 6 As shown, X value represents the horizontal distance from the center of the contact surface between the stress dispersion layer 22 and the photon lead 1 to the center of the laser 3's output end face; Z value represents the vertical distance from the center of the contact surface between the tapered transition layer 21 and the laser 3's end face to the center of the laser 3's contact surface to the laser 3's output end face. Figure 7 As shown, when the Z value is -4μm, the loss is relatively large. Therefore, at the connection between the tapered transition layer 21 and the device end face, the distance between its edge and the edge of the photonic lead 1 is chosen to be 9μm as the final parameter; Figure 8 As shown, the X value has a relatively small impact on the overall loss. When it varies in the range of 11 to 16 μm, the loss value is basically around 1.760 dB. Therefore, the distance between the edge of the stress dispersion layer 22 and the end face of the device is selected as 11 to 16 μm as the final parameter at the connection between the stress dispersion layer 22 and the photon lead 1.

[0054] In this embodiment, the different devices can be a DFB laser and a standard single-mode fiber, respectively; wherein, the DFB laser 3 is made of group III-V materials, and the beam size at the output end face is 4μm×2μm; the standard single-mode fiber 4 is SMF-28, with a core radius of 4.1μm, a core refractive index of 1.44, and a cladding refractive index of 1.4382; the following is a detailed description of the specific working process of this optical waveguide structure between the DFB laser and the single-mode fiber:

[0055] First, the optical signal is emitted from the end face of the DFB laser 3, with a beam size of approximately 4μm × 2μm in an elliptical mode field. This optical field first enters the first tapered waveguide 11 of the photonic lead 1. The initial end face of this waveguide is designed to match the elliptical shape, thereby efficiently capturing optical energy. Subsequently, the light wave gradually transitions to a circular mode field in the tapered region and enters the curved waveguide 12, which is composed of multiple large-radius circular arcs. This curved waveguide can guide the optical path to change direction with extremely low loss, ultimately guiding the optical signal to the second tapered waveguide 13. Here, the optical mode field is gradually expanded from a circle with a radius of 1.1μm to 6.2μm to match the mode field size of the standard single-mode fiber 4, achieving efficient coupling of optical energy to the fiber and completing a full low-loss optical transmission link from the laser to the fiber.

[0056] To ensure the long-term stability of the aforementioned optical path, the support leads 2 at both ends function synchronously. Their tapered transition layers 21, with a relatively large diameter of 2.5–4 μm, are firmly bonded to the end faces of the laser and optical fiber, providing a solid anchoring foundation. The support leads extend upwards in an arc shape, connecting to the main body of the photonic lead 1 through the stress-dispersing layer 22 at their ends, forming a stable triangular support configuration. This structure effectively resists external vibrations and thermal stress, preventing the photonic lead from shifting or collapsing. Furthermore, the consistency in materials and processes between the support leads and the photonic lead, along with the optimized arc design of the connection points, ensures that the mechanical support behavior does not introduce additional optical losses or mode field disturbances, thereby guaranteeing the long-term reliability of the optical transmission link.

[0057] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0058] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optical waveguide structure, characterized in that, It includes photon leads (1) and paired support leads (2); The photonic lead (1) is a three-dimensional freeform waveguide, including a first tapered waveguide (11), a curved waveguide (12), and a second tapered waveguide (13) connected in sequence; the end of the first tapered waveguide (11) away from the curved waveguide (12) and the end of the second tapered waveguide (13) away from the curved waveguide (12) are connected to different device end faces; Each of the support leads (2) has an upward arc-shaped bending structure, including a conical transition layer (21) and a stress dispersion layer (22) connected to each other; the end of the conical transition layer (21) away from the stress dispersion layer (22) is connected to the end face of the device, and the end of the stress dispersion layer (22) away from the conical transition layer (21) is connected to the photon lead (1); The photonic lead (1) and each of the support leads (2) are parallel at the end face of the device, forming an angle greater than 45 degrees and less than 180 degrees at the connection.

2. The optical waveguide structure according to claim 1, characterized in that, The photonic lead (1) and the support lead (2) are made of the same photocurable resin and are integrally formed by the same two-photon exposure process.

3. The optical waveguide structure according to claim 1, characterized in that, In the support lead (2), at the connection between the tapered transition layer (21) and the device end face, the distance between its edge and the edge of the photonic lead (1) is 9 μm, and at the connection between the stress dispersion layer (22) and the photonic lead (1), the distance between its edge and the device end face is 11 to 16 μm.

4. The optical waveguide structure according to claim 1, characterized in that, The first tapered waveguide (11) has a length of 16 μm, and its cross-section near the device end is elliptical with a size of 0.6 μm × 1.5 μm. Its cross-section near the curved waveguide (12) end is circular with a radius of 1.1 μm.

5. The optical waveguide structure according to claim 1, characterized in that, The curved waveguide (12) is 80 μm long and is composed of multiple circular arc segments with a radius of 100 μm connected smoothly. The cross-sections at both ends are circular with a radius of 1.1 μm.

6. The optical waveguide structure according to claim 1, characterized in that, The second tapered waveguide (13) has a length of 100 μm. Its cross-section near the end of the curved waveguide (12) is circular with a radius of 1.1 μm, and its cross-section near the end of the device is circular with a radius of 6.2 μm.

7. The optical waveguide structure according to claim 1, characterized in that, The tapered transition layer (21) has a circular cross-section with a radius of 2.5 μm to 4 μm near the device end, and a circular cross-section with a radius of 2 μm near the stress dispersion layer (22).

8. The optical waveguide structure according to claim 1, characterized in that, The conical transition layer (21) is 10 μm long and has an arc-shaped design with a bending radius of 20 μm.

9. The optical waveguide structure according to claim 1, characterized in that, The stress dispersion layer (22) has a circular cross-section with a radius of 2μm at one end near the conical transition layer (21), and an elliptical cross-section with a size of 2μm×0.6μm and a thickness of 2μm at the other end near the photon lead (1).

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