Area array optical fiber collimator

Abstract

The utility model discloses a surface array optical fiber collimator, is constituted by mould pressing lens array, a plurality of pigtail, a plurality of connecting pipe or ridge hole plate, one side of lens array is array convex surface, the other side is a plurality of ridge inclined plane, one side end surface of connecting pipe or ridge hole plate and lens array gluing, the other side end surface and pigtail gluing, since every optical fiber collimator is through the precise light adjustment between pigtail relative to plano-convex lens, and is fixed after the axial transition through connecting pipe or ridge hole plate, can guarantee the mechanical positioning accuracy index of every collimator and the optical performance index in the whole surface array optical fiber collimator, and the quality can be guaranteed, in addition, the utility model has compact structure and low material cost, and easy to assemble, the yield is high, is suitable for building large array.

Description

Technical Field

[0001] This utility model relates to the field of fiber optic collimator processing in the optical communication industry, specifically a two-dimensional surface array fiber optic collimator. Background Technology

[0002] Two-dimensional fiber collimators are widely used in data centers, aerospace, lidar and other fields. Especially in the current era of rapid development of AI computing, the huge amount of data computing has created a huge demand for two-dimensional fiber collimators.

[0003] The key technical specifications of fiber optic collimators with practical applications in data centers include the mechanical positioning accuracy between collimators and the optical performance of each collimator. The mechanical positioning accuracy includes the positioning accuracy dp of the collimator pitch (typically within 50µm) and the beam parallelism dθ between collimators (typically within 0.01°). The optical specifications of a single collimator include the working distance WD (e.g., 200mm), insertion loss IL (e.g., not greater than 0.5dB), and return loss RL (typically not less than 55dB).

[0004] If a lens array combined with a fiber array is used to fabricate a fiber collimator, the challenge lies in controlling the fiber positioning accuracy to the sub-micron level during the manufacturing of the two-dimensional fiber array. For example, with a lens focal length of 4.5mm, a 1µm deviation in fiber position results in a beam parallelism deviation (dθ) of 0.013°. Existing technologies (such as etched aperture plate arrays and V-groove plate stacks) cannot achieve sub-micron level accuracy. Furthermore, the fiber array has a zero-degree end face, making it impossible to solve the return loss (RL) problem. Therefore, the only solution is to perform independent "light adjustment" on each fiber collimator to achieve the aforementioned mechanical positioning accuracy and optical performance indicators. To address this problem, this invention provides a fiber collimator with a compact structure, low material cost, easy assembly, and high yield. Summary of the Invention

[0005] To address the technical problems mentioned in the background section, this utility model provides the following technical solution:

[0006] A planar fiber collimator, characterized in that it comprises a lens array 1, multiple pigtails 2, and multiple connecting tubes 3. One side of the lens array 1 is an array convex curved surface, and the other side is multiple ridge slopes 11. Each convex curved surface and the ridge slope 11 form a plano-convex lens. The pigtails 2 have a sloping end face 21 with the same inclination angle as the ridge slope 11. Both end faces of the connecting tubes 3 have sloping end faces with the same inclination angle as the ridge slope 11. The left end face 31 of the connecting tube 3 is bonded to the ridge slope 11, and the right end face 32 of the connecting tube 3 is bonded to the sloping end face 21 of the pigtail 2. Each plano-convex lens, after axial transition through a connecting tube 3, forms a fiber collimator with a pigtail 2. Multiple fiber collimators constitute a two-dimensional planar fiber collimator. Alternatively, a planar fiber collimator, characterized in that it comprises a lens array 1... The system comprises multiple pigtails 2 and a ridge perforated plate 4. One side of the lens array 1 is an array convex curved surface, and the other side is multiple ridge slopes 11. Each convex curved surface and the ridge slope 11 form a plano-convex lens. The pigtail 2 has a sloping end face 21 with the same inclination angle as the ridge slope 11. The two end faces of the ridge perforated plate 4 are ridge slopes with the same inclination angle as the ridge slope 11. The left ridge slope 41 of the ridge perforated plate 4 is bonded to the ridge slope 11, and the right ridge slope 42 of the ridge perforated plate 4 is bonded to the sloping end face 21 of the pigtail 2. The ridge perforated plate 4 has an axial array of through holes 43, which correspond one-to-one with the axial direction of the plano-convex lens. After axial transition through the ridge perforated plate 4, a plano-convex lens and a pigtail 2 form an optical fiber collimator. Multiple optical fiber collimators form a two-dimensional planar array optical fiber collimator.

[0007] Preferably, the planar fiber collimator is characterized in that: the ridge slope 11 of the lens array 1, the slope end face 21 of the pigtail 2, the left end face 31 and the right end face 32 of the connecting tube 3, or the left ridge slope 41 and the right ridge slope 42 of the ridge perforated plate 4 have the same tilt angle, the tilt angle being the angle between the normal of each slope and the axis of the fiber collimator, and the tilt angle being not less than 6°.

[0008] Preferably, the optical fiber collimator is characterized in that: the lens array 1 is a two-piece split structure, consisting of a lens array with one side being an array convex curved surface and the other side being a plane, and a ridge array with one side being a plane and the other side being multiple ridge slopes (11), the two planes being glued together.

[0009] By adopting the above technical solution, this utility model has the following beneficial effects:

[0010] Since each fiber collimator is fixed after precise light adjustment between the pigtail 2 and the plano-convex lens, and then axially transitioned through the connecting tube 3 or the ridge perforated plate 4, the mechanical positioning accuracy and optical performance of each collimator in the area array fiber collimator can be guaranteed. In addition, this utility model has a compact structure and low material cost, and is easy to assemble with a high yield. Attached Figure Description

[0011] Figure 1 A schematic diagram of a fiber optic collimator using a connecting tube;

[0012] Figure 2 A schematic diagram of a structure that uses a perforated ridge plate to replace the connecting pipe;

[0013] Figure 3 This is a three-dimensional schematic diagram of the lens array and the ridge perforated plate;

[0014] Figure 4 for Figure 1 The left view of the fiber optic collimator shown. Detailed Implementation

[0015] The technical solutions of the embodiments of this utility model will now be described with reference to the accompanying drawings. The following description is exemplary and is only used to explain this utility model, and should not be construed as limiting it.

[0016] Fiber optic collimators come in various sizes, such as... Figures 1 to 4 As shown, taking an orthogonal array of 16 fibers in 4 rows and 4 columns as an example, the actual fiber collimator may be larger in scale, such as 20*20 with a total of 400 fibers. The distribution of the collimator array may also not be orthogonal, for example, it can be cellular.

[0017] Figure 1 In the configuration, lens array 1 has convex lenses arranged in an array on one side and multiple ridge-shaped inclined surfaces 11 on the other side. The positions of the convex lenses correspond to the positions of the ridge inclined surfaces 11, making each lens a plano-convex lens with one convex end and one inclined end. The direction of the normal of the ridge inclined surface 11 makes an angle of 8° with the axis of the convex lens (commonly referred to as 8-degree tilt in the industry). The tilted plane is designed to meet the return loss (RL) requirement. Typically, an 8° tilt can guarantee RL > 58dB, and at least a 6° tilt is required to achieve RL > 55dB. Therefore, the tilt angle must be no less than 6°, which is why, as mentioned in the background section, the zero-degree end-face fiber array scheme cannot meet the RL requirement. The multiple ridge inclined surfaces 11 are configured as follows: Figure 1The "washboard" structure is best suited for molding. For example, the lower mold core has 16 recesses, and the upper mold core has four sloping surfaces in the "washboard" shape. Molding can easily achieve the pitch positioning accuracy dp mentioned in the background art.

[0018] Lens array 1 can be as follows Figure 1 The component can be a single piece or two separate pieces. If separate, one piece is a lens array with one convex side and the other flat side, while the other is a ridge array with one flat side and the other a ridge surface. The two flat surfaces are glued together for use. The advantage of separate pieces is that one type of ridge array can be used to accommodate lens arrays with different focal lengths, and for molding, separate pieces are easier and cheaper to manufacture than single pieces. However, for large arrays, single pieces offer better reliability.

[0019] The fiber optic pigtail 2 has an optical fiber threaded through its inner hole, and its end face 21 is also machined with the same 8° bevel angle. The direction of the 8° bevel end face 21 is set parallel to the tilt direction of the ridge surface 11. Multiple connecting tubes 3 are located between the multiple pigtails 2 and the lens array 1. The end faces on both sides are also machined with an 8° bevel angle. The left bevel 31 is attached to the ridge bevel 11 of the lens array 1, and the right bevel 32 is attached to the bevel end face 21 of the pigtail 2. The connecting tubes 3 can be glued to the lens array 1 or the pigtails 2 first. For example, the connecting tubes 3 can be glued to the lens array 1 first. After all 16 connecting tubes 3 are glued, the pigtails 2 are glued on one by one. During operation, the tail of the pigtail 2 is held with a clamp (not shown in the figure) and swapped with the same collimator standard part (golden sample). After adjusting the light transmission (Alingment), the end face between the connecting tube 3 and the pigtail 2 is glued. The light adjustment and gluing are existing technologies in the industry, and will not be described in detail here.

[0020] It should be noted that the tubular connecting tube 3 can ensure that the adhesive will not block the fiber core of the pigtail 2 (nor will it block the light-passing aperture at the ridge slope 11) when the adhesive is applied, forming what is known in the industry as a "glued-free optical path" structure. A "glued-on optical path" structure is not advisable for large area array collimators.

[0021] After each of the pigtails 2 is fixed, a 4*4 array collimator with a total of 16 fibers is obtained. The pitch positioning accuracy dp is guaranteed by molding, the beam parallelism dθ between collimators is guaranteed by dimming, the collimator working distance WD is guaranteed by lens design (focal length), the insertion loss IL is guaranteed by dimming, and the return loss RL is guaranteed by the tilting surface. As a specific embodiment, the array lens 1 has a focal length of 4.5mm, a lens pitch of 2.0mm, an axial length of 6.0mm for each lens, an angle of 8° for the ridge surface 11, a pigtail 2 with an outer diameter of 1.0mm and a length of 4.0mm, and a connecting tube 3 with an outer diameter of 1.6mm, an inner diameter of 0.7mm, and an axial length of 1.2mm.

[0022] Here, some technical data of this utility model solution need to be explained in detail:

[0023] Taking a 1.0mm diameter pigtail 2 as an example, considering that the dimming gripping fixture cannot interfere with the fixed pigtail 2 in the horizontal and vertical spatial structures, the lens pitch is set to 2.0mm, that is, (2.0-1.0) / 2=0.5mm of space gap is left for the gripping fixture operation. The actual gripping fixture wall thickness is 0.2mm, and there is 0.3mm of space available for movement. The outer diameter of the connecting tube 3 is set to 1.6mm and the inner diameter is set to 0.7mm. This ensures a suitable wall thickness of 0.45mm and leaves sufficient space for adhesive overflow, so as not to affect the adhesive bonding. That is, when bonding, the adhesive on the left side of the connecting tube 3 should not seep into the light-transmitting aperture, nor should it interfere with the assembly of the other connecting tube 3. The adhesive on the right side of the connecting tube 3 should not seep into the fiber core, and should also ensure sufficient overlap strength with the end face 21 of the pigtail. In this embodiment, the width of the overlap ring on the inclined surface 32 is (1.0-0.7) / 2=0.15mm, but the end face area outside the overlap ring (1.6-1.0) / 2=0.3mm can be used to apply ring adhesive to the cylindrical surface of the pigtail 2.

[0024] During fabrication, first fix the lens array 1 and connecting tube 3. Select a standard part with excellent WD, IL, and RL ratings as the master piece, and swap all the pigtails 2 to be adjusted and fixed with it. After adjusting and fixing one pigtail 2, shift the standard part by one pitch, and then hold another pigtail 2 to make the next collimator. Before all pigtails 2 are fixed, only the standard part can be shifted and its spatial angle cannot be changed. This is to ensure the beam parallelism dθ between the collimators.

[0025] Obviously, the connecting tube 3 is only a structural component rather than an optical component that transmits light, and its material can be glass, ceramic or metal.

[0026] When the array size is small, such as only 16 optical fibers in the embodiment, it is not difficult to bond the 16 connecting tubes 3 to the lens array 1. However, for large arrays such as 100 fibers, bonding 100 connecting tubes 3 is not suitable. In this case, a ridge perforated plate 4 with ridge slope arrays on both sides can be used instead. The ridge surface 41 on the left side of the ridge perforated plate 4 is bonded to the lens array 1, and the ridge surface 42 on the right side of the ridge perforated plate 4 receives the bonding of the pigtail 2. The ridge perforated plate 4 has pre-made through holes 43. Referring to the aforementioned embodiment, the inner diameter of the through hole 43 of the ridge perforated plate 4 is set to 0.7 mm, and the axial length is 1.2 mm. Taking glass as an example, the ridge perforated plate 4 is manufactured by molding, which can ensure the angular accuracy and geometric tolerance of the ridge slopes on both sides. The inner hole can be formed during molding, or the non-perforated ridge plate can be pressed first and then the hole can be drilled, for example, by using a precision engraving machine or laser drilling.

[0027] In summary, this utility model application provides a structure for a fiber optic array preparer. Since each fiber collimator is precisely adjusted between the pigtail 2 and the plano-convex lens, and then fixed axially using the connecting tube 3 or the ridge perforated plate 4, the mechanical positioning accuracy of the overall array collimator and the optical performance of each collimator can be guaranteed, ensuring quality. Furthermore, for large arrays, the ridge perforated plate 4 is preferably used instead of the connecting tube 3, resulting in a compact structure, low material cost, convenient assembly, and high yield.

[0028] The embodiments of this utility model have been described above. Those skilled in the art can make modifications, substitutions, and variations to the embodiments without departing from the principles and spirit of this utility model, as long as they are within the scope of the claims of this utility model, they are protected by patent law.

Claims

1. A planar fiber collimator, characterized in that: Composed of a lens array (1), multiple pigtails (2), and multiple connecting tubes (3), the lens array (1) has a convex curved surface on one side and multiple ridge slopes (11) on the other side. Each convex curved surface and the ridge slope (11) form a plano-convex lens. The pigtails (2) have inclined end faces (21) with the same tilt angle as the ridge slopes (11). The two end faces of the connecting tubes (3) are inclined end faces with the same tilt angle as the ridge slopes (11). The left end face (31) of the connecting tube (3) is glued to the ridge slope (11), and the right end face (32) of the connecting tube (3) is glued to the slope end face (21) of the pigtail (2). The plano-convex lens, after axial transition through the connecting tube (3), forms an optical fiber collimator with a pigtail (2). Multiple optical fiber collimators form a two-dimensional array optical fiber collimator; or, a lens array (1), multiple pigtails (2), and a ridge perforated plate (4) are used to construct... The lens array (1) has an array of convex curved surfaces on one side and multiple ridge slopes (11) on the other side. Each convex curved surface and the ridge slope (11) form a plano-convex lens. The pigtail (2) has a sloping end face (21) with the same tilt angle as the ridge slope (11). The two end faces of the ridge perforated plate (4) are ridge slopes with the same tilt angle as the ridge slope (11). The left ridge slope (41) of the ridge perforated plate (4) is connected to the ridge slope. The surfaces (11) are glued together. The right ridge slope (42) of the ridge perforated plate (4) is glued together with the slope end face (21) of the pigtail (2). The ridge perforated plate (4) has an axial array of through holes (43). The array of through holes (43) corresponds one-to-one with the axial direction of the plano-convex lens. After the plano-convex lens is axially transitioned through the ridge perforated plate (4), it forms an optical fiber collimator with a pigtail (2). Multiple optical fiber collimators form a two-dimensional surface array optical fiber collimator.

2. The fiber optic collimator according to claim 1, characterized in that: The ridge slope (11) of the lens array (1), the inclined end face (21) of the pigtail (2), the left end face (31) and right end face (32) of the connecting tube (3), or the left ridge slope (41) and right ridge slope (42) of the ridge perforated plate (4) have the same tilt angle, which is the angle between the normal of each slope and the axis of the optical fiber collimator, and the tilt angle is not less than 6°.

3. The fiber optic collimator according to claim 1, characterized in that: The lens array (1) is a two-piece split structure, consisting of a lens array with a convex curved surface on one side and a flat surface on the other side, and a ridge array with a flat surface on one side and multiple ridge slopes (11) on the other side, with the two flat surfaces glued together.

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