Fixing apparatus and method for attaching optical fibers to V-grooves of photonic integrated circuits

Abstract

A system for passively aligning an interface between an optical fiber and a photonic integrated circuit (PIC), the system comprising: an input frame; an actuator; and an output frame. The actuator is arranged to apply a force to the input frame along a force axis. The output frame includes a tip for picking up a plate and transmitting force to the plate. The output frame is connected to the input frame such that it can be tilted relative to the input frame, and the output frame is resiliently biased relative to the input frame to a position where the tip is aligned along the force axis.

Description

[0001] Cross-references to related applications

[0002] This patent application is a successor to U.S. Patent Application No. 17 / 358,314, filed on June 25, 2021, the disclosure of which is incorporated herein by reference in its entirety. Background Technology

[0003] Photonic integrated circuits (PICs) may include input-output (I / O) interfaces in the form of V-grooves where optical fibers are received. Therefore, the manufacture of PIC-based electronic devices and network hardware may involve placing and securing optical fibers from fiber optic cables into the V-grooves of the PIC. Active attachment manufacturing methods involve carefully and precisely aligning the optical fibers with the I / O interface. Passive attachment involves stripping an optical fiber tape to expose fibers with a spacing approximately matching the V-groove spacing, roughly aligning the entire tape with the I / O interface, and then pressing a cap or spacer onto the exposed fibers to force them into the V-grooves.

[0004] In passive attachment, the inclined surface defining the V-groove guides the fiber into place, thus compensating for inaccuracies in coarse alignment. However, a significant force is required to deflect all fibers and set them into proper position. Therefore, while known passive attachment methods can tolerate slight lateral misalignment of the band relative to the V-groove, problems can arise, including inconsistent positioning across multiple fibers, when the plane of the I / O interface is not arranged perfectly orthogonal to the direction of the pressing force. Furthermore, caps or spacers made of relatively soft materials such as plastic may not effectively transmit the pressing force to all fibers and could be damaged during the pressing process. Summary of the Invention

[0005] Various aspects of this disclosure relate to a passive attachment system. The alignment system may include: a tip, such as a vacuum tip for lifting a plate and applying a vacuum force to the plate; and a carriage or clamp for transmitting pressing force to the tip. The clamp may include: an input frame on which pressing force can be applied; and an output frame from which the tip can extend. The input frame may be coupled to the output frame via one or more resilient bias elements that allow the output frame to tilt relative to the input frame as the clamp presses the plate down onto the fiber and PIC.

[0006] The one or more biasing elements allow the output frame to tilt relative to the input frame in any direction within a range of up to 360° around the axis of the pressing force applied to the input frame. The one or more biasing elements can be, for example, a large spring, such as a helical spring, positioned between the input and output frames, above the tip and centered on the axis of the pressing force on the input frame; or, in other examples, multiple springs of any type positioned between the input and output frames at different angular locations around the axis of the pressing force on the input frame. In a particular example, four equally elastic helical springs can be positioned between the input and output frames, radially equidistant from the axis of the input force on the input frame, and uniformly angularly spaced from each other.

[0007] The plate can be made of glass. After the optical fiber is positioned in the V-groove and pressure is maintained on the cover, curing radiation can be transmitted through the plate. A light-curing adhesive, such as epoxy, can be applied to either or both of the I / O interface and the optical fiber itself before the pressing step and cured during or after the pressing step. The tip can also be glass, allowing curing light to be projected through it. Example glasses suitable for the cover and tip include quartz, Pyrex glass, and borosilicate glass. After the adhesive has cured, the load can be removed from the cover.

[0008] On the other hand, a system for passively aligning an interface between an optical fiber and a photonic integrated circuit (PIC) may include: an input frame; an actuator; and an output frame. The actuator may be arranged to apply a force to the input frame along a force axis. The output frame may include a tip to pick up a plate and transmit force to it. The output frame may be connected to the input frame such that the output frame can be tilted relative to the input frame, and the output frame is elastically biased relative to the input frame to a position where the tip is aligned along the force axis.

[0009] In another arrangement according to any of the foregoing, the system may include a vacuum assembly configured to vent air from a channel having an opening at the tip.

[0010] In another arrangement according to any of the foregoing, the system may include a spring that connects the input frame to the output frame.

[0011] In another arrangement according to any of the foregoing, the system may include a plurality of springs connecting the input frame to the output frame, wherein each spring is positioned at a different corresponding position about the force axis.

[0012] In another arrangement according to any of the above, the plurality of springs can be balanced in terms of elasticity and arrangement of each spring, such that the biasing around the force axis between the input frame and the output frame is symmetrical.

[0013] In another arrangement according to any of the above, each of the plurality of springs may be located at an equal radial distance from the force axis and at an equal angular distance from each circumferentially adjacent spring on any side.

[0014] In another arrangement according to any of the above, the plurality of springs may be four springs, each of which is defined at a corner of a square arrangement centered on the force axis.

[0015] In another arrangement according to any of the above, the tip may extend along the force axis.

[0016] In another arrangement according to any of the above, the tip may be transparent.

[0017] In another arrangement according to any of the above, the output frame can be freely tilted away from the position where the tip is aligned on the force axis in any direction across a 360° range relative to the force axis.

[0018] In another arrangement according to any of the foregoing, the system may include a rack that carries the input frame, actuator, and output frame in a movable position.

[0019] On the other hand, a method of coupling an optical cable to a PIC may include: aligning the exposed optical fibers of the cable with a V-groove of an input-output (I / O) interface of the PIC; aligning a board over the exposed optical fibers and the I / O interface; and applying a force along a force axis to a clamp arranged to transmit the force to the board until each optical fiber is in place in its respective V-groove. The clamp may include: an input frame to which a force is applied; and an output frame. The output frame may include a tip extending from the output frame to transmit the force to the board, the output frame being freely tiltable relative to the input frame and resiliently biased relative to the input frame toward positions in which the tip extends along the force axis and the output frame is spaced apart relative to the input frame.

[0020] In another arrangement according to any of the foregoing, the method may include using a vacuum to secure the PIC to the base prior to the step of applying force along the force axis.

[0021] In another arrangement according to any of the above, the method may include using a vacuum connected to the tip to pick up the plate.

[0022] In another arrangement according to any of the foregoing, the method may include applying an adhesive to either or both of the I / O interface and the optical fiber prior to the force application step.

[0023] In another arrangement according to any of the foregoing, the method may include curing the adhesive by light projected through the plate after each optical fiber is in place in the corresponding V-groove.

[0024] In another arrangement according to any of the above, light can also be projected through the tip.

[0025] In another arrangement according to any of the above, the output frame can be freely tilted away from the position where the tip is aligned on the force axis in any direction across a 360° range relative to the force axis.

[0026] In another arrangement according to any of the foregoing, the step of aligning the plate may include controlling the frame to move the clamp while the plate is held in place by the tip of the clamp.

[0027] In another arrangement according to any of the foregoing, the method may include a splitting step prior to the step of aligning the exposed optical fibers with the V-groove, the splitting step comprising providing exposed optical fibers by removing the cladding from the ends of the cable until the length of each exposed optical fiber is at least five times the length of the V-groove. Attached Figure Description

[0028] Figure 1A This is a perspective view of the photonic integrated circuit (PIC) on the support.

[0029] Figure 1B yes Figure 1A An elevation view of a portion of the input / output (I / O) interface of a PIC.

[0030] Figure 2A The illustration shows the steps for picking up the lid using the output frame.

[0031] Figure 2B yes Figure 2A The top plan view of the output frame.

[0032] Figure 2C yes Figure 2A The front elevation view of the output frame.

[0033] Figure 3A It is a perspective view of a split, partially stripped optical jumper cable.

[0034] Figure 3B Is Figure 1A Top plan view of the fiber optic cable aligned above the PIC.

[0035] Figure 3C yes Figure 3B The top plan view of the arrangement, wherein an adhesive is applied to the arrangement.

[0036] Figure 3D yes Figure 3B The top plan view of the layout, in which the optical fiber advances further on the PIC.

[0037] Figure 4 Is Figure 3D Press down on the arrangement Figure 2B The output frame is a perspective view.

[0038] Figures 5A to 5C Is Figure 3D The arrangement is gradually pressed further downwards. Figure 2A Cross-sectional elevation view of the lid.

[0039] Figures 6A to 6C Is Figure 1A Front view of the clamp pressing down on the PIC.

[0040] Figure 7 It is to package the PIC with Figures 1A to 6C The flowchart shows the process of arranging and assembling the equipment.

[0041] Figure 8 It is possible to... Figure 7 The process yields the cross-sectional elevation view of the PIC package. Detailed Implementation

[0042] Figure 1A The illustration shows support step 114, in which a photonic integrated circuit (PIC) 14 is placed on a support member 18. The PIC 14 includes input / output (I / O) interfaces 22. Figure 1B As shown, the I / O interface 22 includes several V-shaped grooves 26. Each V-shaped groove 26 includes two opposing sidewalls 26, which slope towards each other from the relatively wide top of the V-shaped groove to the relatively narrow bottom of the V-shaped groove. Thus, each pair of opposing sidewalls 26 has an overall shape similar to the letter "V".

[0043] Figure 2AThe illustration depicts a pickup step 118 in which the cap 34 is picked up by the tip 38. The illustrated example cap 34 is a plate, which can be made of any material rigid enough to press the optical fiber into the V-groove 26 according to the process described in this disclosure. In some examples, the cap 34 can be bonded to some adhesive, which can also bond the PIC 14 and the optical fiber. In some examples, the cap 34 is transparent to some visible light, ultraviolet light, or electromagnetic radiation of at least some wavelengths. Specific examples of suitable materials that can form the cap 34 include glass, such as quartz, pyrex glass, and borosilicate glass, or polymeric plastics, such as acrylic resins.

[0044] The tip 38 can be made of any material that can be used to make the cap 34. The picking step can be performed before, after, or during the supporting step 114. In some examples, the tip 38 is made of a material that is at least as hard as the material used to make the cap 34. In the illustrated example, a closed channel extends through the tip 38 to the opening at the tip tip. Figure 2A (Not visible in the center), and the hose 46 is connected to the end of the channel opposite the opening. Thus, the hose 46 can be used to empty the channel and generate a suction force through the opening of the tip 38 to pick up the lid 38. However, in alternative examples, the tip 38 includes any known device or combination of devices capable of lifting and carrying the lid 34 and applying a force to the lid along the force axis X.

[0045] Continue to refer to Figure 2A In case of reference Figure 2B and Figure 2C The tip 38 is part of the output frame 30. In the illustrated example, four helical springs 42 are distributed in a plane orthogonal to the force axis X. Figure 2B In the example, springs 42 are arranged symmetrically and at equal distances from the force axis X, but in other arrangements, the springs may be symmetrical and at different distances, or even asymmetrical. Throughout this disclosure, the terms "upward" and "downward" are relative to... Figure 2C The perspective is defined, but the process according to this disclosure can be performed such that the actual directions of up and down correspond to the use of these terms herein. The tip 38 extends in the downward direction along the force axis X away from its connection point with the remaining output frame 30, and the helical springs 42 extend upward away from their contact points with the output frame. Thus, applying a downward force to each spring 42 will drive the output frame 30 downward, but the elastic nature of the springs will allow the output frame to tilt relative to the force axis X when such a force is applied. Furthermore, the downward force on the springs 42 will bias the output frame 30 along the force axis X toward the alignment of the tip 38.

[0046] However, the illustrated arrangement of the four helical springs 42 is merely one example of an arrangement suitable for biasing the output frame 30 according to the process of this disclosure. Other examples of suitable biasing arrangements include a single large helical spring centered on the force axis X, or any type and any number of springs arranged symmetrically about the force axis. A downward force on a biasing arrangement according to any of these examples will force the output frame 30 downward and bias the output frame along the force axis X toward the tip 38 while allowing the output frame to tilt relative to the force axis X.

[0047] Figure 3A An example of the result of the splitting step 120 performed on the fiber optic patch cable 50 is illustrated. In other examples, the splitting step 120 can be performed on any component including the fiber optic strip 58. The splitting step can be performed before, after, or during either or both of the support step 114 and the pick-up step 118. In the splitting step 120, the cladding 54 is cut back to expose the exposed fiber 58, and the exposed fibers are cut such that their lengths relative to each other are suitable for effective placement within the I / O interface 22. In the illustrated example, the exposed fibers 58 are cut such that their free ends are each located at a corresponding point along a common line 60 extending perpendicular to the fibers themselves. However, the appropriate relative lengths of the exposed fibers 58 can vary depending on the configuration of the I / O interface 22.

[0048] Figure 3B The diagram illustrates alignment step 124, in which the exposed optical fibers 58 are roughly aligned with their respective V-grooves 26 in the I / O interface 22 of the PIC 14. Alignment step 124 is performed after splitting step 120 and can be performed before, during, or after either or both of support step 114 and pick-up step 118. Alignment step 124 is optional because cable 50 can be placed on the I / O interface 22 before splitting step 120, and the splitting step can be performed while the cable is held in place, such that the resulting exposed optical fibers 58 are roughly aligned with their respective V-grooves 26.

[0049] exist Figure 3CIn the illustrated adhesion step 128, adhesive 62 is applied to either or both of the I / O interface 22 and the free end of the exposed optical fiber 58. Adhesive 62 can be any flowable adhesive capable of securing the exposed optical fiber 58 to the PIC 14, such as, for example, epoxy resin. In some examples, adhesive 62 is a light or electromagnetic wave curable epoxy resin. In the illustrated example, adhesion step 128 is shown to include applying adhesive 62 to both the exposed optical fiber 58 and the I / O interface 22 after the alignment step 124; however, adhesion step 128 can be performed before, during, or after any one or any combination of the support step 114, the pick-up step 118, and the subsequent splitting and alignment steps 120, 124. If adhesion step 128 is performed before the splitting step 120, adhesive 62 is applied to the I / O interface but not to the exposed optical fiber 58.

[0050] Figure 3D The illustration shows an optional advancing step 132, in which the exposed optical fibers 58 are advanced toward the ends of their respective V-grooves 26, and fine alignment between the optical fibers and the V-grooves can be performed after the adhesion step 128. If the exposed optical fibers 58 have been sufficiently aligned with their respective V-grooves 26 at the end of the adhesion step 128, such that the pressing step 136, detailed below, will generate effective optical coupling between the cable 50 and the PIC 14, the advancing step 132 can be omitted.

[0051] Figure 4 The pressing step 136 is illustrated. Pressing step 136 is performed after supporting step 114, picking step 118, splitting step 120, and adhering step 128. Pressing step 136 is also performed after either or both of alignment step 124 and forward step 132 are performed. Thus, at the start of pressing step 136, PIC 14 is supported by support member 18, cover 34 is picked up by tip 38, cable 50 is split, exposed optical fibers 58 are fully aligned with their corresponding V-grooves 26, adhesive 62 has been applied to either or both of the exposed optical fibers and V-grooves, and the cover and tip are aligned over the exposed optical fibers and I / O interface. During pressing step 136, a downward force is applied to a bias arrangement coupled to output frame 30, i.e., spring 42 in the illustrated example, to drive cover 34 downward along the force axis X toward the intended final or permanent position of the cover on PIC 14.

[0052] like Figures 5A to 5CAs shown, throughout pressing step 136, the cap 34 applies a downward force to the free end of the exposed optical fiber 58. While the cap 34 does not need to be made of glass, glass is an example of a material that can be used to make the cap, allowing it to transmit a sufficient amount of force to the exposed optical fiber 58 with little or no damage to the resulting cap. If as... Figure 5A As shown, the exposed optical fiber 58 is laterally eccentric from its corresponding V-groove 26 at the start of pressing step 136, as... Figure 5B and Figure 5C As shown, the free end of the optical fiber will slide along one of the sidewalls 58 toward the center of the V-groove as the fiber is driven by the cap 34 toward the bottom of the V-groove. The cap 54 should be cut back far enough to allow the exposed optical fibers 58 to be deflected as far as needed to reach the bottom and center of their respective V-grooves 26.

[0053] refer to Figures 6A to 6C The input frame 66 is used to apply a downward force to the biasing arrangement (i.e., spring 42 in the illustrated arrangement) during pressing step 136. The input frame 66, the biasing arrangement, and the output frame 30 together provide the clamp. Either or both of the input frame 66 and the output frame 30 can be connected to a frame or lifting system capable of laterally moving the clamp. The frame or lifting system, or the separate pressing device, may also include an actuator capable of applying a force along the force axis X toward the input frame 66 to perform pressing step 136.

[0054] Assuming input frame 66, etc. Figures 6A to 6C As shown, when fixed to a rotational position relative to the force axis X, the biasing arrangement provided by spring 42 balances the elasticity and arrangement of the spring to bias the output frame 30 relative to the input frame 66 toward a position where its tip 38 is aligned along the force axis X. Since the input frame 66 is coupled to the output frame 30 via the elastic biasing arrangement (i.e., spring 42 in the illustrated example), the force along the force axis X can be transmitted from the input frame to the output frame while the output frame is still able to tilt relative to the force axis and the input frame. Therefore, if the PIC 14 is supported in an uneven position, such as... Figures 6A to 6C As shown, where the upper surface of the PIC is not located in a plane orthogonal to the force axis X, the output frame 30 can be tilted relative to the input frame 66 while a downward force is applied to the input frame along the force axis, thereby allowing the tip 38 to tilt orthogonally extending from the upper surface of the PIC. The bias arrangement allows the output frame 30 to tilt relative to the input frame 66 in any direction within a range of up to 360° about the force axis X. By tilting orthogonally extending from the upper surface of the PIC 14, the tip 38 can tilt within the cover 34 (in... Figures 6A to 6CPress down on the (invisible) surface of the PIC so that the cover will lie flat on the upper surface of the PIC and apply sufficient pressure to all exposed optical fibers 58 to press the exposed optical fibers into their respective V-grooves 28.

[0055] Figure 7 The diagram illustrates a process 110 for coupling cable 50 to PIC 14 according to the steps and apparatus described above. In setup phase 112, the aforementioned support step 114, pick-up step 118, splitting step 120, and adhesion step 128 are performed in any order. Also as described above, alignment step 124 and advancing step 132 are optional. However, if performed, alignment step 124 is performed after splitting step 120, and advancing step 132 is performed after adhesion step 128. If either or both of alignment step 124 and advancing step 132 are performed, they are performed before the end of setup phase 112. Pressing step 136 is performed after setup phase 112 and continues until the exposed optical fibers 58 reach a satisfactory depth within their respective V-grooves 26.

[0056] Curing step 140 occurs after pressing step 136, and simultaneously, sufficient load is retained on cap 34 to hold cap and exposed fiber 58 in their intended final or permanent position relative to PIC 14. Curing step 140 includes any process necessary to fully solidify adhesive 62 such that load can be removed from cap 34 and cap and exposed fiber 58 will remain in their intended position. Depending on the type of adhesive 62 used, curing step 140 may include waiting for the adhesive to solidify over time, applying a catalyst to the adhesive, or curing the adhesive with electromagnetic radiation. In some examples, electromagnetic radiation may be light, such as visible light or ultraviolet light. If electromagnetic radiation is used to cure adhesive 62, the radiation can propagate through any of the aforementioned means. For example, cap 34 may be transparent to the type of radiation used to cure adhesive 62, and the radiation can pass through cap and irradiate the adhesive. Tip 38 or the entire output frame 30 may also be transparent to the radiation used to cure adhesive 32, and the radiation can pass through both tip and cap 34 and irradiate the adhesive. Alternatively or additionally, radiation may be applied to the adhesive 62 through PIC 14. After curing step 140 is completed, the load may be removed from the cap 34 in unloading step 144.

[0057] Figure 8An example of a portion of the PIC package obtained after completing process 110 is shown. Each exposed fiber 58 is positioned at its lowest possible location within a corresponding V-groove. In the illustrated example, the width of each exposed fiber 58 places the lowest possible location of the exposed fiber within its corresponding V-groove 26 above the bottom of the V-groove, such that each exposed fiber contacts both sidewalls 38 of its corresponding V-groove but not the bottom of the corresponding V-groove. Cured adhesive 62 adheres a cap 38 to the exposed fiber 58 and adheres the exposed fiber as a whole to the sidewalls 28 and PIC 14. Thus, the cap 14, fiber 58, and PIC 14 are permanently connected, such that the fiber optics are optically coupled to their respective V-grooves 26, and the cap protects the fiber.

[0058] While the concepts herein have been described with reference to specific examples, it should be understood that these examples are merely illustrative of the principles and applications of the presented concepts. Therefore, it should be understood that many modifications can be made to the illustrative examples and other arrangements can be conceived without departing from the spirit and scope of the presented concepts as defined by the appended claims.

Claims

1. A system for passively aligning an interface between an optical fiber and a photonic integrated circuit (PIC), the system comprising: Input frame; An actuator, the actuator being arranged to apply a force to the input frame along a force axis; An output frame, the output frame including a tip for picking up a plate and transmitting force to the plate, the output frame being connected to the input frame such that the output frame is tilted relative to the input frame and the output frame is elastically biased relative to the input frame to a position where the tip is aligned on the force axis; Multiple springs connect the input frame to the output frame, wherein each spring is positioned at a different corresponding position about the force axis; as well as A vacuum assembly and a hose, the vacuum assembly being configured to vent air from a channel having an opening at the end of the tip, the hose being connected to the end of the channel opposite to the opening, wherein the hose extends from the tip through the input frame and the output frame in a direction consistent with the force axis.

2. The system according to claim 1, wherein, The elasticity and arrangement of the plurality of springs are balanced for each spring, such that the bias between the input frame and the output frame is symmetrical about the force axis.

3. The system according to claim 1, wherein, Each of the plurality of springs is located at an equal radial distance from the force axis and at an equal angular distance from each circumferentially adjacent spring on either side.

4. The system according to claim 1, wherein, The plurality of springs are four springs, each of which is defined at a corner of a square arrangement centered on the force axis.

5. The system according to claim 1, wherein, The tip extends along the force axis.

6. The system according to claim 1, wherein, The tip is transparent.

7. The system according to claim 1, wherein, Across relative to the force axis In any direction within the range of degrees, the output frame can tilt freely away from the position where the tip is aligned on the force axis.

8. The system of claim 1, comprising a rack that carries the input frame, actuator, and output frame in a movable position.

9. A method for coupling an optical cable to a PIC, the method comprising: Align the exposed optical fiber of the cable with the V-groove of the input-output I / O interface of the PIC. Align the board over the exposed optical fiber and the I / O interface; as well as A force is applied along the force axis to a clamp, the clamp being arranged to transmit the force to the plate until each of the optical fibers is in place in a corresponding V-groove, the clamp comprising: The force is applied to the input frame; An output frame, comprising a tip extending from the output frame for transmitting the force to the plate, the output frame being freely tiltable relative to the input frame and elastically biased relative to the input frame at a position extending toward the tip along the force axis of the force, and the output frame being spaced apart relative to the input frame; and A plurality of springs connect the input frame to the output frame, wherein each spring is positioned at a different corresponding location about the force axis; and Vacuum is used to pick up the plate by means of a channel and a hose connected to the tip, wherein the channel has an opening at the end of the tip, and the hose is connected to the end of the channel opposite to the opening and extends from the tip through the input frame and the output frame in a direction consistent with the force axis.

10. The method of claim 9, comprising: Vacuum is used to secure the PIC to the base prior to the step of applying force along the force axis.

11. The method of claim 9, comprising: Before the step of applying force, apply adhesive to either or both of the I / O interface and the optical fiber.

12. The method of claim 11, comprising: After each optical fiber is in place within its corresponding V-groove, the adhesive is cured by light projected through the plate.

13. The method according to claim 12, wherein, The light is also projected through the tip.

14. The method according to claim 9, wherein, Across relative to the force axis In any direction within the range of degrees, the output frame can tilt freely away from the position where the tip is aligned on the force axis.

15. The method according to claim 9, wherein, The step of aligning the plate includes: controlling the frame to move the clamp while the plate is held in place by the tip of the clamp.

16. The method of claim 9, comprising: A splitting step prior to the step of aligning the exposed optical fibers with the V-groove, the splitting step comprising: providing the exposed optical fibers by removing the cladding from the ends of the cable until each exposed optical fiber has a length at least five times the length of the V-groove.

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