Coupling fixture and coupling device assembly

Abstract

The present invention provides a coupling and fixing device and a coupling device assembly. The coupling and fixing device includes a substrate fixing portion and at least one fixed axis portion, wherein the substrate fixing portion is provided with a central groove for accommodating and fixing a lithium niobate thin film chip, and at least one end of the central groove is provided with a substrate groove; each substrate groove is provided with a fixed axis portion, and the fixed axis portion is fixedly connected to the substrate groove. The lithium niobate thin film chip is fixed in the central groove of the substrate fixing portion, and the conical lens optical fiber is fixed in the fixed axis portion, and the conical lens optical fiber is coupled with the waveguide in the lithium niobate thin film chip. After the angle of the conical lens optical fiber and the waveguide are aligned, the fixed axis portion is fixed in the substrate groove to achieve relative fixation of the position of the conical lens optical fiber and the waveguide, so that the application of the lithium niobate thin film modulator is not limited by the inability to fix the position of the conical optical fiber and the waveguide, and the practicality is enhanced, which is conducive to large-scale promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of optical waveguide devices, and in particular to a coupling fixing device and a coupling device assembly. Background Art

[0002] The trend of high-speed optical communication systems places high demands on high-speed optoelectronic devices, among which the key components are high-speed optoelectronic modulators. At present, the external modulator using lithium niobate is still the best choice for long-distance backbone networks. This is mainly because of the excellent electro-optical modulation characteristics of lithium niobate based on the Pockels effect, especially the lithium niobate modulator shows unparalleled advantages in generating high-baud-rate multi-level signals. Recently, lithium niobate thin films on insulators have become a promising platform for forming waveguide devices with good confinement, and lithium niobate thin film modulators with low driving voltage and ultra-high electro-optical bandwidth have also been demonstrated. Since traditional lithium niobate modulators are formed by low-index contrast waveguides, the optical confinement is weak, and the driving electrode must be placed far away from the optical waveguide to minimize absorption loss, which leads to an increase in driving voltage. Therefore, traditional lithium niobate modulators are bulky and have low modulation efficiency. Lithium niobate thin films can overcome this weakness of traditional lithium niobate modulators and become a very promising new material.

[0003] The lithium niobate thin film optical waveguide is set on the lithium niobate thin film chip. The mode field of the waveguide is only about 1 / 6 of the mode field of the optical fiber. When the two are coupled, the two ends of the waveguide need to be finely designed with mode spot conversion structures to improve the coupling efficiency. At present, laboratories basically use conical lens optical fiber and waveguide coupling docking to test optoelectronic performance indicators. During the test, conical lens optical fibers are set on both sides of the waveguide, one side is connected to the light source, and the other side is connected to the optical power meter. The conical lens optical fibers on both sides are clamped by a three-dimensional adjustment frame, and the positions and angles of the conical lens optical fibers on both sides are adjusted in space to maximize the output power of the light to complete the coupling of the conical lens optical fiber and the waveguide. After the test is completed, the conical lens optical fiber is removed from the three-dimensional adjustment frame. In actual applications, the relative position between the conical lens optical fiber and the waveguide cannot be fixed, which limits the practicality of the lithium niobate thin film modulator, which is not conducive to the application and promotion of the lithium niobate thin film modulator.

[0004] Therefore, it is necessary to provide a coupling fixing device and a coupling device assembly. Summary of the invention

[0005] In view of this, the present invention provides a coupling fixture and a coupling fixture assembly, by fixing the lithium niobate film chip and the conical lens optical fiber on the coupling fixture respectively, so as to fix the relative positions of the two, thereby overcoming the defects of the prior art.

[0006] The coupling and fixing device provided by the present invention comprises: a substrate fixing portion, the substrate fixing portion is provided with a central groove for accommodating and fixing a lithium niobate thin film chip, and at least one end of the central groove is provided with a substrate groove; at least one fixed axis portion, each of the substrate grooves is provided with a fixed axis portion, and the fixed axis portion is fixedly connected to the substrate groove.

[0007] Optionally, the substrate grooves are respectively opened at two opposite ends of the central groove; the number of the fixed axis parts is two, and they are respectively arranged in two of the substrate grooves.

[0008] Optionally, clamping plates extend from opposite sides of each substrate slot.

[0009] Optionally, a through hole is penetrated through the fixed axis portion, and the tapered lens optical fiber passes through the through hole.

[0010] Optionally, a first adhesive layer is disposed in the through hole.

[0011] Optionally, a second adhesive layer is provided in the central groove.

[0012] Optionally, the bottom of the substrate groove is configured to be arc-shaped.

[0013] Optionally, the coupling and fixing device further comprises a positioning mark, and the positioning mark is used to guide the lithium niobate thin film chip to be fixed at a set position of the central groove so that the waveguide is coupled with the tapered lens optical fiber.

[0014] The present invention also provides a coupling device assembly, including a lithium niobate thin film chip, an input-end tapered lens optical fiber and an output-end tapered lens optical fiber, and also includes any of the above-mentioned coupling fixing devices.

[0015] Optionally, the coupling device assembly also includes: a first three-dimensional adjustment frame, which clamps the fixed axis portion connected to the input-end tapered lens optical fiber through a first clamp, and is used to adjust its position and angle in space; or / and a second three-dimensional adjustment frame, which clamps the fixed axis portion connected to the output-end tapered lens optical fiber through a second clamp, and is used to adjust its position and angle in space.

[0016] Compared with the prior art, the above technical solution provided by the present invention has at least the following beneficial effects: the lithium niobate thin film chip is fixed in the central groove of the substrate fixing part, the conical lens optical fiber is fixed in the fixed axis part, the conical lens optical fiber is coupled with the waveguide in the lithium niobate thin film chip, and after the angle of the conical lens optical fiber and the waveguide are aligned, the fixed axis part is fixed in the substrate groove to achieve relative fixation of the position of the conical lens optical fiber and the waveguide, so that the application of the lithium niobate thin film modulator is not limited by the inability to fix the position of the optical fiber and the waveguide, the practicality is enhanced, and it is conducive to large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a substrate fixing portion according to an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of the connection relationship between the fixed axis portion and the tapered lens optical fiber according to an embodiment of the present invention;

[0019] Figure 3 A schematic diagram of the connection relationship between the coupling fixture according to one embodiment of the present invention, the tapered lens optical fiber, and the lithium niobate thin film chip;

[0020] Figure 4 A schematic diagram of the connection relationship between the coupling fixture and the tapered lens optical fiber and the lithium niobate thin film chip according to another embodiment of the present invention;

[0021] Figure 5 A perspective view of a coupling device assembly according to an embodiment of the present invention;

[0022] Figure 6 A three-dimensional perspective view of a lithium niobate thin film chip according to an embodiment of the present invention;

[0023] Figure 7 for Figure 6 A side view of the lithium niobate thin film chip shown;

[0024] Figure 8 A side view of a lithium niobate thin film chip according to another embodiment of the present invention.

[0025] Reference numerals:

[0026] 1: substrate fixing part; 11: center groove; 12: substrate groove; 13: fixed base; 14: clamping plate; 2: lithium niobate thin film chip; 21: base layer; 22: supporting layer; 23: lithium niobate thin film; 24: cladding layer; 25: waveguide; 251: mode spot conversion part; 3: fixed axis part; 4: conical lens optical fiber. DETAILED DESCRIPTION

[0027] The embodiments of the present invention will be further described below in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only simplified descriptions for the convenience of describing the present invention, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0028] Figure 1 A schematic diagram of a substrate fixing portion according to an embodiment of the present invention; Figure 2 A schematic diagram of the connection relationship between the fixed axis portion and the tapered lens optical fiber according to an embodiment of the present invention; Figure 3 A schematic diagram of the connection relationship between the coupling fixture according to one embodiment of the present invention, the tapered lens optical fiber, and the lithium niobate thin film chip; Figure 4 This is a schematic diagram of the connection relationship between the coupling fixture and the tapered lens optical fiber and the lithium niobate thin film chip according to another embodiment of the present invention. Figure 1-Figure 4 As shown, the coupling and fixing device provided by the present invention includes a substrate fixing portion 1 and at least one fixed axis portion 3.

[0029] The substrate fixing portion 1 is provided with a central groove 11 for accommodating and fixing the lithium niobate thin film chip 2, and at least one end of the central groove 11 is provided with a substrate groove 12; each substrate groove 12 is provided with a fixed axis portion 3, and the fixed axis portion 3 is fixedly connected to the substrate groove 12.

[0030] The lithium niobate thin film chip 2 is fixed in the central groove 11 of the substrate fixing part 1, and the conical lens optical fiber 4 is passed through and fixed on the fixed axis part 3. Then, by adjusting the spatial position and angle of the fixed axis part 3, the conical lens optical fiber 4 and the waveguide 25 are coupled. After the coupling is completed, the fixed axis part 3 is fixed in the substrate groove 12 to achieve relative fixation of the positions of the conical lens optical fiber 4 and the waveguide 25, so that the application of the lithium niobate thin film modulator is not limited by the inability to fix the positions of the optical fiber and the waveguide, the practicality is enhanced, and it is conducive to large-scale promotion and application.

[0031] The substrate fixing portion 1 cooperates with the fixed axis portion 3 to couple the tapered lens optical fiber 4 with the waveguide 25, instead of directly bonding the tapered lens optical fiber and the waveguide to achieve coupling, which has the following advantages: first, if the coupling is directly bonded, the glue adheres to the lens end face, causing the coupling efficiency to decrease; while the coupling fixture is used to assist in coupling, the glue adhesion to the lens end face can be avoided, effectively ensuring the coupling efficiency; secondly, if the coupling is directly bonded, the filled glue affects the bonding firmness and environmental reliability; while the coupling fixture is used to assist in coupling, the non-contact coupling and fixation of the tapered lens optical fiber and the lithium niobate thin film waveguide is achieved, the flexibility of coupling is ensured, and the coupling efficiency of the tapered lens optical fiber is improved.

[0032] The lithium niobate thin film chip 2 can be loosely matched with the central groove 11. To further improve the connection stability, a second adhesive layer is optionally provided in the central groove 11. The second adhesive layer is provided in the central groove 11. When the lithium niobate thin film chip 2 is placed in the central groove 11, it can be directly bonded and connected with the central groove 11, eliminating the glue dripping process and further improving the coupling efficiency.

[0033] In this embodiment, the lithium niobate thin film chip 2 is connected to the substrate fixing portion 1 by gluing, for example, by UV glue. Other fixed connection methods may also be used without affecting the coupling process between the tapered lens optical fiber 4 and the waveguide 25.

[0034] Optionally, the fixed axis portion 3 is penetrated with a through hole, and the tapered lens optical fiber 4 passes through the through hole. The tapered lens optical fiber 4 passes through the through hole on the fixed axis portion 3 and is fixedly connected to the fixed axis portion 3, which simplifies the connection relationship between the tapered lens optical fiber 4 and the fixed axis portion 3.

[0035] In the present embodiment, the fixed axis portion 3 is a rectangular parallelepiped, and its length, width, and height are 2 mm, 2 mm, and (2-3) mm, respectively. A through hole is provided at the center of the fixed axis portion 3 to accommodate the tapered lens fiber 4 passing therethrough. The tapered lens fiber 4 can fit in the through hole gap, and after adjusting the length of the tapered lens fiber 4 exposed from the fixed axis portion 3 (the tapered lens portion extends out of the through hole), the tapered lens fiber 4 is fixed in the through hole. In the present embodiment, the through hole has a circular cross-section and a circular radius of (128-130) μm. The tapered lens portion of the tapered lens fiber 4 is exposed outside the through hole and is fixed in the through hole by ultraviolet glue. In practical applications, the shape and size of the fixed axis portion 3 can be adjusted as needed, and the size of the through hole can also be adjusted accordingly according to the size of the tapered lens fiber.

[0036] To further improve the connection stability, optionally, a first adhesive layer is provided in the through hole. The first adhesive layer is provided in the through hole, and when the tapered lens optical fiber 4 passes through the through hole, it can be directly bonded and connected with the first adhesive layer, and the tapered lens optical fiber 4 is fixed in the through hole, further improving the coupling efficiency. In this embodiment, after the coupling is completed, the fixed axis portion 3 is connected to the substrate groove 12 by gluing, for example, by ultraviolet glue or flexible glue. Under the premise of not affecting the coupling process between the tapered lens optical fiber 4 and the waveguide 25, other fixed connection methods can also be used.

[0037] In this embodiment, the tapered lens optical fiber 4 is cylindrical, except for the end thereof facing the lithium niobate thin film chip 2 which is tapered.

[0038] In this embodiment, in order to improve the temperature reliability of the overall structure and prevent the thermal expansion coefficients of different materials from being inconsistent during the coupling process, thereby affecting the coupling efficiency, the substrate fixing portion 1 and the fixed axis portion 3 are made of the same material, which is silicon dioxide. Both may also use other materials whose refractive index meets the coupling conditions.

[0039] The substrate groove 12 can be opened at any one of the two opposite ends of the central groove 11. After the conical lens optical fiber 4 is fixed to the fixed axis portion 3, the coupling of the conical lens optical fiber 4 and the waveguide 25 is achieved by adjusting the spatial position and angle of the fixed axis portion 3. After the coupling is completed, the fixed axis portion 3 is fixed in the opened substrate groove 12 to achieve the fixation of the relative position of the conical lens optical fiber 4 and the waveguide 25.

[0040] Optionally, the substrate grooves 12 are respectively opened at opposite ends of the central groove 11; the number of the fixed axis portions 3 is two, and they are respectively arranged in the two substrate grooves 2. In this arrangement, after the waveguide 25 fixed in the central groove 11 is coupled with the tapered lens optical fiber 4 fixed on the fixed axis portions 3 at opposite ends of the central groove 11, the fixed axis portions 3 at both ends are respectively fixed in the substrate grooves 12 at both ends, so that the positions of the waveguide 25 and the tapered lens optical fiber 4 at both ends are kept relatively fixed.

[0041] In this embodiment, the substrate grooves 12 are respectively opened at the opposite ends of the central groove 11, and two fixed axis portions 3 are provided to match them, and the tapered lens optical fibers 4 are respectively fixedly connected to the two fixed axis portions 3. After coupling is completed, the two fixed axis portions 3 are respectively fixed to the two substrate grooves 12, so that the positions of the waveguide 25 and the tapered lens optical fibers 4 at the input and output ends are kept relatively fixed.

[0042] In this embodiment, the central groove 11 extends from the top end of the substrate fixing portion 1 to one side of the bottom end and is located in the middle, and the two substrate grooves 12 are symmetrically distributed along the central groove 11. The depth of the central groove 11 is slightly smaller than the depth of the substrate groove 12, that is, the bottom of the substrate groove 12 is slightly higher than the bottom of the central groove 11. The substrate groove 12 can clamp and limit the lithium niobate thin film chip 2 in the central groove 11.

[0043] In this embodiment, the fixed axis portion 3 is disposed in the middle of the substrate groove 12 , and the substrate groove 12 clamps and limits the fixed axis portion 3 ; the fixed axis portion 3 is opposite to the lithium niobate thin film chip 2 and is spaced apart from each other.

[0044] Optionally, clamping plates 14 are extended from opposite sides of each substrate groove 12. The clamping plates 14 are provided to further clamp the fixed axis portion 3 after the fixed axis portion 3 is fixedly connected to the substrate groove 12, thereby improving the connection stability between the fixed axis portion 3 and the substrate groove 12. At the same time, the extended clamping plates 14 can also limit the lithium niobate thin film chip 2 fixed in the central groove 11, thereby improving the connection stability between the lithium niobate thin film chip 2 and the central groove 11.

[0045] In this embodiment, the substrate fixing portion 1 includes a fixing base 13 and at least two relatively distributed clamping plates 14, and the fixing base 13 is sequentially provided with the substrate groove 12 on the left, the central groove 11 and the substrate groove 12 on the right (such as Figure 1 As shown in FIG. 1 , each of the two opposite sides of the substrate slot 12 is provided with a clamping plate 14, that is, the fixed base 13 is located near the two opposite ends and is respectively disposed toward Figure 1 Two clamping plates 14 arranged opposite to each other extend from the upper middle portion. The two clamping plates 14 located at the same end of the fixing base 13 and the fixing base 13 each enclose one substrate slot 12 .

[0046] In this embodiment, the cross section of the fixed base 13 is rectangular, and the four clamping plates 14 are of the same shape, all of which are rectangular parallelepipeds of uniform size. The total length of the substrate fixing portion 1 is 11 to 18 mm, and the width is 5 to 6 mm. In practical applications, the number of the clamping plates 14 can be adjusted as needed, and the shapes and sizes of the fixed base 13 and the clamping plates 14 can be adjusted, and the multiple clamping plates 14 can also be set to different sizes and shapes.

[0047] Optionally, the bottom of the substrate groove 12 is set to be an arc shape. When the tapered lens optical fiber 4 is coupled with the waveguide 25, precise positioning is achieved by adjusting the spatial position and angle of the fixed axis portion 3 that fixes the tapered lens optical fiber 4. The fixed axis portion 3 is set in the substrate groove 12, and the bottom of the substrate groove 12 is set to be an arc shape. When the fixed axis portion 3 is rotated, the substrate groove 12 can provide a larger operating space for the fixed axis portion 3 in height.

[0048] In this embodiment, one substrate groove 12 is provided at each of the two opposite ends of the central groove 11, and the groove bottoms of the two substrate grooves 12 are both set to arcs with the same curvature, and the arcs are raised toward the direction of the fixed base 13, and are symmetrically distributed relative to the axis of the substrate grooves 12, and the lowest point of the arc is almost flush with the groove bottom of the central groove 11. According to actual use requirements, the groove bottom of the substrate groove 12 on one side can also be set to an arc, and the curvature of the arc can also be set to different values ​​according to the space requirements of the fixed axis part 3.

[0049] Optionally, the coupling and fixing device further includes a positioning mark (not shown), and the positioning mark is used to guide the lithium niobate thin film chip 2 to be fixed at a set position of the central groove 11 so that the waveguide 25 is coupled with the tapered lens optical fiber 4. The positioning mark is provided to facilitate the lithium niobate thin film chip 2 to find a fixed connection position with the central groove 11 more accurately and quickly, thereby facilitating the rapid coupling of the tapered lens optical fiber 4 with the waveguide 25.

[0050] In this embodiment, the positioning mark can be set at any position of the coupling and fixing device, for example, on the fixed base 13 or in the substrate groove 12, etc. The positioning mark can also be set to any form of mark, as long as it can provide guidance for the installation position of the lithium niobate thin film chip 2 when the lithium niobate thin film chip 2 is fixedly connected to the center groove 11.

[0051] In this embodiment, the through hole opened on the fixed axis portion 3 is located at the center of the fixed axis portion 3, and the fixed axis portion 3 is disposed in the substrate groove 12, so the tapered lens fiber 4 disposed in the through hole is substantially located at the center of the substrate groove 12, and the tapered lens fiber 4 is coupled with the waveguide 25 on the lithium niobate thin film chip 2, so the positioning mark guides the waveguide 25 to be distributed along the center line of the central groove 11, so as to facilitate coupling with the tapered lens fiber 4. In practical applications, if the position of the tapered lens fiber 4 changes, the positioning mark can also guide the waveguide 25 to be positioned to a position matching the tapered lens fiber 4 accordingly.

[0052] Figure 5A perspective view of a coupling device assembly according to an embodiment of the present invention; Figure 6 A three-dimensional perspective view of a lithium niobate thin film chip according to an embodiment of the present invention; Figure 7 for Figure 6 A side view of the lithium niobate thin film chip shown; Figure 8 A side view of a lithium niobate thin film chip according to another embodiment of the present invention.

[0053] like Figure 5-Figure 8 As shown, the present invention also provides a coupling device assembly, including a lithium niobate thin film chip 2, an input-end tapered lens optical fiber and an output-end tapered lens optical fiber, and also includes the coupling fixing device described in any of the above embodiments.

[0054] When the input-end tapered lens fiber and the output-end tapered lens fiber are coupled with the waveguide 25 on the lithium niobate thin film chip 2, the lithium niobate thin film chip 2 is fixed to the substrate fixing part 1 of the coupling fixture, and the input-end tapered lens fiber and the output-end tapered lens fiber are respectively fixed to the fixed axis part 3 of the coupling fixture, and then the spatial position and angle of the fixed axis part 3 are adjusted, and after the input-end tapered lens fiber and the output-end tapered lens fiber are aligned with the waveguide 25, the two fixed axis parts 3 fixed with the input-end tapered lens fiber and the output-end tapered lens fiber are respectively fixed in the substrate groove 12 of the coupling fixture where they are located, so as to achieve relative fixation of the positions of the input-end tapered lens fiber, the output-end tapered lens fiber and the waveguide 25, so that the application of the lithium niobate thin film modulator is not limited by the inability to fix the positions of the optical fiber and the waveguide, the practicality is enhanced, and it is conducive to large-scale promotion and application.

[0055] In this embodiment, the input end tapered lens fiber and the output end tapered lens fiber are both made of SMF-28 fiber that is precisely ground into a tapered shape, and an optical microsphere lens is processed at the tip to achieve the purpose of expanding the numerical aperture of the fiber and increasing the light receiving ability. The fiber coating diameter is 250μm, the cladding diameter is 125μm, and the mode spot size is about 3-4μm. The tapered lens fiber shown in the figure does not include a coating layer.

[0056] like Figure 6 , Figure 7As shown, in this embodiment, the lithium niobate film chip 2 is a rectangular parallelepiped as a whole, with a width of 2 to 3 mm and a total length of 5000 to 10000 μm. The lithium niobate film chip 2 includes a base layer 21, a supporting layer 22, a lithium niobate film 23 and a coating layer 24 from bottom to top. A low-loss ridge waveguide 25 is manufactured on the lithium niobate film 23 by an etching process, and the etching depth is 200 to 300 nm. In order to appropriately expand the size of the mold spot, mold spot conversion parts 251 are mirror-symmetrically arranged at opposite ends of the waveguide 25. The width of the mold spot conversion part 251 gradually decreases in the direction extending toward the end of the lithium niobate film 23. The waveguide 25 is a rectangular parallelepiped in the middle and a trapezoidal column with mirror-symmetrical ends. The length, width and height of the mold spot conversion part 251 are 200 to 400 μm, 0.2 to 0.6 μm (away from the end of the lithium niobate film 23) and 200 to 300 nm, respectively. The cladding layer 24 disposed on the upper part of the lithium niobate film 23 is provided with a groove on the side facing the lithium niobate film 23. The shape and size of the groove match the waveguide 25, so that the waveguide 25 is placed in the groove. The cladding layer 24 surrounds the waveguide 25, further realizing the expansion of the mode spot. In this embodiment, the material used for the cladding layer 24 is silicon dioxide, and other materials with a refractive index between the optical fiber and the lithium niobate film 23, such as silicon nitride, can also be used. In practical applications, the size and shape of the lithium niobate film chip 2 and the waveguide 25 can be adjusted as needed, and accordingly, the size and shape of the groove provided in the cladding layer 24 are also adjusted accordingly according to the change of the waveguide 25.

[0057] If the mode spot conversion part 251 is not provided at the opposite ends of the waveguide 25, and the tapered lens fiber 4 is directly coupled to the waveguide 25, the loss will be approximately 5-6dB / end. By providing the mode spot conversion part 251 of the above-mentioned size specifications at both ends of the waveguide 25, after the mode spot conversion, the mode field of the waveguide 25 can be expanded from 1μm to 2-3μm, which matches the mode spot size of the tapered lens fiber 4, and the coupling loss can be reduced to 2-4dB / end.

[0058] The waveguide 25 in this embodiment is coupled with the tapered lens optical fiber 4, which can reduce the processing cost and is conducive to the practical promotion of lithium niobate thin film modulators.

[0059] Optionally, the coupling device assembly further includes a first three-dimensional adjustment frame or / and a second three-dimensional adjustment frame, wherein the first three-dimensional adjustment frame clamps the fixed axis portion 3 connected to the input end tapered lens optical fiber through a first clamp and is used to adjust its position and angle in space; the second three-dimensional adjustment frame clamps the fixed axis portion 3 connected to the output end tapered lens optical fiber through a second clamp and is used to adjust its position and angle in space. The three-dimensional adjustment frame is provided and used to finely adjust the spatial position and angle of the fixed axis portion 3, thereby finely adjusting the position and angle of the input end tapered lens optical fiber and the output end tapered lens optical fiber, thereby improving the coupling accuracy.

[0060] In this embodiment, the first three-dimensional adjustment frame and the second three-dimensional adjustment frame are provided to respectively finely adjust the input end tapered lens fiber and the output end tapered lens fiber. In the above scheme, the first three-dimensional adjustment frame and the second three-dimensional adjustment frame can be implemented by commercially available three-dimensional adjustment frames.

[0061] The following further describes the use process of the coupling and fixing device.

[0062] like Figure 5 As shown, the left side of the figure is the input end tapered lens fiber, and the right side is the output end tapered lens fiber. The lithium niobate thin film chip 2 is fixed in the central groove 11 by UV glue under the guidance of the positioning mark, and the input end tapered lens fiber and the output end tapered lens fiber are respectively inserted into the through holes opened on the two fixed axis parts 3, so that the tapered lens parts of the tapered lens fibers are exposed from the through holes respectively. After the positions are adjusted appropriately, the input end tapered lens fiber and the output end tapered lens fiber are respectively glued in the through holes where they are located by UV glue, and the fixed axis part 3 fixed with the input end tapered lens fiber is fixed to the first three-dimensional adjustment frame by a first clamp, and is suspended on Figure 5 The fixed axis portion 3 having the output end tapered lens optical fiber is fixed in the substrate groove 12 on the left side of the middle, and is fixed on the second three-dimensional adjustment frame through a second clamp and is suspended on the second three-dimensional adjustment frame. Figure 5In the substrate groove 12 on the right side of the middle, a light source is connected to one side of the input end tapered lens fiber, and an optical power meter is connected to one side of the output end tapered lens fiber, the spatial position and angle of the input end tapered lens fiber and the output end tapered lens fiber are adjusted, and the output power value is monitored by the optical power meter. When the power value is maximum, ultraviolet glue is filled in the gap between the fixed axis part 3 fixed with the input end tapered lens fiber and the substrate groove 12, and ultraviolet glue is filled in the gap between the fixed axis part 3 fixed with the output end tapered lens fiber and the substrate groove 12, and the two fixed axis parts 3 are fixed to their respective substrate grooves 12. After coupling and fixing are completed, the light source and the optical power meter are removed, and the fixedly connected whole is irradiated under ultraviolet lamp for three minutes to solidify the ultraviolet glue. In order to further release the stress of the ultraviolet glue and ensure the temperature reliability of the overall structure, after irradiation with ultraviolet lamp, the fixedly connected whole is placed in a high temperature box for (85°C) aging for 36 to 48 hours.

[0063] By adopting the coupling and fixing device and the coupling device assembly of the present invention, when the conical lens optical fiber 4 is coupled with the waveguide 25 on the lithium niobate thin film chip 2, the lithium niobate thin film chip 2 is fixed in the central groove 11 of the substrate fixing portion 1, and the conical lens optical fiber 4 is fixed to the fixed axis portion 3. Then, by adjusting the spatial position and angle of the fixed axis portion 3, the conical lens optical fiber 4 and the waveguide 25 are coupled. After the angles of the conical lens optical fiber 4 and the waveguide 25 are aligned, the fixed axis portion 3 is fixed in the substrate groove 12 to achieve relative fixation of the positions of the conical lens optical fiber 4 and the waveguide 25. This makes the application of the lithium niobate thin film modulator not limited by the inability to fix the positions of the optical fiber and the waveguide, enhances its practicality, and is conducive to large-scale promotion and application.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coupling fixing device, characterized in that: include: A substrate fixing part, wherein the substrate fixing part is provided with a central groove for accommodating and fixing a lithium niobate thin film chip, at least one end of the central groove is provided with a substrate groove, the central groove and the substrate groove are both provided on the substrate fixing part, the relative positions of the central groove and the substrate groove are fixed, and the groove bottom of the substrate groove is set to be arc-shaped; At least one fixed axis portion, each of the substrate slots is provided with one fixed axis portion, and the fixed axis portion is fixedly connected to the substrate slot; The fixed axis portion is opposite to the lithium niobate thin film chip and is spaced apart from it; The fixed axis portion is penetrated by a through hole, through which the tapered lens optical fiber passes, and after adjusting the length of the tapered lens optical fiber exposed from the fixed axis portion, the tapered lens optical fiber is fixed in the through hole; After the tapered lens optical fiber is fixed to the fixed axis portion, the tapered lens optical fiber is coupled with the waveguide on the lithium niobate thin film chip by adjusting the spatial position and angle of the fixed axis portion. After the coupling is completed, the fixed axis portion is fixed in the substrate groove; The substrate fixing portion cooperates with the fixed axis portion to couple the tapered lens optical fiber with the waveguide, replacing direct bonding of the tapered lens optical fiber with the waveguide to achieve coupling, thereby achieving non-contact coupling and fixing of the tapered lens optical fiber with the waveguide.

2. The coupling and fixing device according to claim 1, characterized in that: The base plate grooves are respectively formed at opposite ends of the central groove; The number of the fixed axis parts is two, and they are respectively arranged in the two substrate grooves.

3. The coupling fixing device according to claim 2, characterized in that : Clamping plates extend from opposite sides of each substrate slot.

4. The coupling and fixing device according to any one of claims 1 to 3, characterized in that: A first adhesive layer is arranged in the through hole.

5. The coupling and fixing device according to any one of claims 1 to 3, characterized in that: A second adhesive layer is arranged in the central groove.

6. The coupling and fixing device according to any one of claims 1 to 3, characterized in that: The coupling fixture further comprises: A positioning mark, wherein the positioning mark is used to guide the lithium niobate thin film chip to be fixed at a set position of the central groove so that the waveguide is coupled to the tapered lens optical fiber.

7. A coupling device assembly, comprising a lithium niobate thin film chip, an input end tapered lens optical fiber and an output end tapered lens optical fiber, characterized in that: It also includes a coupling and fixing device as described in any one of claims 1-6.

8. The coupling device assembly according to claim 7, characterized in that: The coupling device assembly also includes: A first three-dimensional adjustment frame, wherein the first three-dimensional adjustment frame clamps the fixed axis portion connected to the input end tapered lens optical fiber through a first clamp, and is used to adjust its position and angle in space; Or / and a second three-dimensional adjustment frame, the second three-dimensional adjustment frame clamps the fixed axis part connected to the output end tapered lens optical fiber through a second clamp, and is used to adjust its position and angle in space.

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