Low-stress fiber clamping and alignment device for ultra-high polarization extinction ratio generation

Abstract

The present invention discloses a low-stress optical fiber clamping and alignment device for generating an ultra-high polarization extinction ratio. The device comprises an optical fiber sample module, an adjustable magnetic clamping module, a binocular vision system module, a coaxial adjustment and alignment module, and an angular rotation and measurement module. The optical fiber sample module comprises a first optical fiber sample and a second optical fiber sample; the optical fiber adjustable magnetic clamping module comprises a first adjustable magnetic clamp and a second adjustable magnetic clamp; the coaxial adjustment and alignment module comprises a first coaxial adjustment and alignment module and a second coaxial adjustment and alignment module; and the binocular vision system module, the second coaxial adjustment and alignment module, and the angular rotation and measurement module are fixed to a marble table. This device can achieve extremely low-stress clamping and precise coaxial alignment of optical fibers, and has the advantages of low clamping stress, high alignment accuracy, and a wide range of applications. It can be used in the field of polarization extinction ratio test instrument calibration.

Description

Technical Field

[0001] The invention belongs to the field of testing and measurement, and relates to a low-stress clamping and alignment device for optical fibers, and in particular to a low-stress clamping and alignment device for optical fibers with an ultra-high polarization extinction ratio. Background Art

[0002] Polarization optical devices are essential components of high-precision optical measurement and sensing systems. Their extinction ratio (ER) is a crucial parameter for evaluating device performance and a key factor in determining optical measurement accuracy and sensing system sensitivity. Therefore, testing and evaluating the ER of polarization optical devices is closely linked to the development of high-precision optical measurement and sensing systems. Improving the accuracy of ultra-high PER measurement results requires instrument calibration, necessitating the ability to controllably generate an ultra-high PER. Traditional methods, such as rotating polarizers, are limited by the polarizer material properties and can only achieve a maximum PER of 50dB, failing to achieve ultra-high PERs. Polarization-maintaining fiber, due to its unique waveguide structure, can achieve ultra-high PERs exceeding 70dB. However, external stresses, such as compression, can introduce crosstalk into PMA fibers, reducing their PER. Therefore, developing a clamping method with extremely low stress is crucial for this purpose.

[0003] In 2018, Song Li and others disclosed a fiber optic clamping device (CN209256753U), which uses magnets to provide clamping force to clamp the optical fiber, but the clamping force is large and uncontrollable, which will damage the optical fiber. In 2019, Chen Lei and others disclosed a fiber optic clamping device and a fiber optic detection device (CN211627406U), which uses a threaded rod to drive two clamps to clamp the optical fiber, which can effectively fix the optical fiber, but cannot clamp the optical fiber with low stress. In the same year, Zhao Liang and others disclosed a fiber optic positioning and clamping device (CN212095985U), which uses suction holes to introduce negative pressure into the suction groove to adsorb the optical fiber, thereby improving the efficiency of clamping the optical fiber, but the optical fiber can move freely axially. In 2019, Zhang Mingda et al. disclosed a fiber clamping device (CN210968571U) that uses a rotating member and a fixed member to adjust the size of the fiber through-hole through bolts, while also clamping the fiber with bolts. Although this device allows fibers of different apertures to pass through the clamp, it does not consider the issue of low-stress clamping of the fiber. It can be seen that current fiber clamping devices do not consider the ability to clamp the fiber while applying extremely low stress to ensure the occurrence of a controllable polarization extinction ratio. Summary of the Invention

[0004] The present invention provides a low-stress clamping and alignment device for optical fibers with ultra-high polarization extinction ratios. The device can achieve extremely low-stress clamping and precise coaxial alignment of optical fibers. It has the advantages of low clamping stress, high alignment accuracy, and a wide range of applications. It can be used in the field of calibration of polarization extinction ratio test instruments.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A low-stress optical fiber clamping and alignment device for ultra-high polarization extinction ratio generation, comprising an optical fiber sample module, an adjustable magnetic clamping module, a binocular vision system module, a coaxial adjustment and alignment module, and an angle rotation and measurement module, wherein:

[0007] The optical fiber sample module includes a first optical fiber sample and a second optical fiber sample having the same structure;

[0008] The optical fiber adjustable magnetic clamping module includes a first adjustable magnetic clamp and a second adjustable magnetic clamp with the same structure;

[0009] The coaxial adjustment and alignment module includes a first coaxial adjustment and alignment module and a second coaxial adjustment and alignment module, and the first coaxial adjustment and alignment module and the second coaxial adjustment and alignment module both have five-dimensional adjustment functions of pitch, yaw, horizontal, vertical and front and back;

[0010] The first optical fiber sample is clamped on a first adjustable magnetic clamp, the first adjustable magnetic clamp is mounted on a first coaxial adjustment and alignment module, and the first coaxial adjustment and alignment module is mounted on the angle rotation and measurement module;

[0011] The second optical fiber sample is clamped on a second adjustable magnetic clamp, and the second adjustable magnetic clamp is mounted on a second coaxial adjustment and alignment module;

[0012] The binocular vision system module observes the alignment status of the first optical fiber sample and the second optical fiber sample from both horizontal and vertical directions;

[0013] The binocular vision system module, the second coaxial adjustment and alignment module, and the angle rotation and measurement module are fixed on a marble table.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. Low-stress fiber samples are made by bonding polarization-maintaining optical fibers to double-layer glass tubes. An adjustable magnetic clamp clamps the outer glass tube of the fiber sample, isolating the effect of clamping stress on the optical fiber. This allows for extremely low-stress clamping of the polarization-maintaining optical fiber, maintaining its low crosstalk characteristics and ensuring an ultra-high polarization extinction ratio.

[0016] 2. The double-layer glass tube structure of the low-stress optical fiber sample designed in the present invention is flexible and can achieve low-stress clamping of optical fibers of different types and diameters with the help of an adjustable magnetic clamp, thus having a wide range of applications.

[0017] 3. The present invention realizes the coaxial alignment of optical fibers through precise adjustment of the five-dimensional position of the optical fibers and real-time observation of the alignment status. The optical fibers are precisely coaxially rotated by the angle rotation and measurement module to realize the controllable occurrence of polarization extinction ratio in an ultra-large range.

[0018] 4. The device of the present invention includes a precise adjustment mechanism and an auxiliary observation mechanism required for optical fiber alignment, has high alignment position adjustment accuracy, is easy to operate, easy to maintain, and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the overall installation diagram;

[0020] Figure 2 This is a sample picture of optical fiber;

[0021] Figure 3 It is a diagram of a low stress clamping device;

[0022] Figure 4 This is a diagram of a binocular vision alignment device;

[0023] Figure 5 This is a diagram of a coaxial adjustment and alignment device;

[0024] Figure 6 This is a diagram of the angle rotation and measurement device. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below with reference to the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the spirit and scope of the technical solution of the present invention should be included in the scope of protection of the present invention.

[0026] The present invention provides a low-stress clamping and alignment device for optical fibers with ultra-high polarization extinction ratios. The design concept is to first produce an optical fiber sample that can be clamped with low stress, then use precision threads to adjust the angles of the clamp's pressure foot and base with high precision, use magnetic force to make the clamp clamp the optical fiber sample with low stress, and then use a coaxial adjustment and alignment device to adjust the alignment state of the optical fiber sample. At the same time, a microscope binocular visual observation device is used to accurately observe the alignment state of the optical fiber sample to assist in alignment. Figures 1-6 As shown, the device includes an optical fiber sample module 8, an adjustable magnetic clamping module 9, a binocular vision system module 10, a coaxial adjustment and alignment module, and an angle rotation and measurement module, wherein:

[0027] 1) The fiber sample module 8 includes a first fiber sample 81 and a second fiber sample 82; the fiber adjustable magnetic clamp module 9 includes a first adjustable magnetic clamp 91 and a second adjustable magnetic clamp 92; and the coaxial adjustment and alignment module includes a first coaxial adjustment and alignment module 11 and a second coaxial adjustment and alignment module 12. The first adjustable magnetic clamp 91 clamps and secures the first fiber sample 81 and is mounted on the first coaxial adjustment and alignment module 11. The three are mounted and secured as a whole on the angle rotation and measurement module. The second adjustable magnetic clamp 92 clamps and secures the second fiber sample 82. The two are mounted as a whole on the second coaxial adjustment and alignment module 12. The binocular vision system module 10, the second coaxial adjustment and alignment module 12, and the angle rotation and measurement module are fixed on the marble table 7.

[0028] 2) The first optical fiber sample 81 consists of a polarization-maintaining optical fiber 811, a first thin glass tube 812, a second thin glass tube 813, and a thick glass tube 814. The inner diameters of the first and second thin glass tubes 812, 813 are slightly larger than the diameters of the polarization-maintaining optical fiber 811, and the outer diameters are slightly smaller than the inner diameter of the thick glass tube 814. The first and second thin glass tubes 812, 813 are bonded to the outside of the polarization-maintaining optical fiber 811 with a spacing of 3 mm. During bonding, it is necessary to ensure that the glue does not adhere to each other after being fixed. The thick glass tube 814 is bonded to the outside of the first and second thin glass tubes 812, 813 in the center using soft silicone. The first thin glass tube 812 and the first thin glass tube of the polarization-maintaining optical fiber 811 are bonded at the bonding point A8. 121. Glue is applied at the first thin glass tube glue point B8122, as well as the second thin glass tube glue point C8131 and the second thin glass tube glue point D8132 between the second thin glass tube 813 and the polarization-maintaining optical fiber 811, so that the two can be fixed on the polarization-maintaining optical fiber 811; glue is applied at the first thick glass tube glue point 8141 between the first thin glass tube 812 and the thick glass tube 814, as well as the second thick glass tube glue point 8142 between the second thin glass tube 813 and the thick glass tube 814; the second optical fiber sample 82 has the same structure as the first optical fiber sample 81.

[0029] 3) The first magnetic fixture 91 consists of a precision threaded knob 911, a base 912, an upper magnet 913, a silicone gasket 914, a pressure foot 915, and a lower magnet 916. Its function is to finely adjust the distance between the pressure foot 915 and the base 912 by adjusting the precision threaded knob 911 so that the silicone gasket 914 can just press the first optical fiber sample 81. The base 912 is provided with a rotating shaft fixing hole 9121, a V-shaped fixing groove 9122, a lower magnet fixing hole 9123, a precision threaded top screw slot 9124, a base fixing shaft 9125 and a fiber hole 9126; the rotating shaft fixing hole 9121 is used to connect with the pressure foot 915; the V-shaped fixing groove 9122 is used to place the first optical fiber sample 81; the lower magnet fixing hole 9123 is used to place the lower magnet 916; the precision threaded top screw slot 9124 is used to support the precision threaded top screw knob 911; the base fixing hole 9125 is used to fix the position of the clamp; the fiber hole 9126 allows the first optical fiber sample 81 to pass through. The presser foot 915 includes a presser foot fixing hole 9151, a silicone gasket fixing hole 9152, an upper magnet fixing hole 9153, and a precision threaded through hole 9154. The presser foot fixing hole 9151 mainly cooperates with the rotating shaft fixing hole 9121 of the base 912 to form a whole, and allows the presser foot 915 to have rotation space; the silicone gasket fixing hole 9152 is used to determine the position of the silicone gasket 914 that presses the first optical fiber sample 81, so that the silicone gasket 914 adheres here; the upper magnet fixing hole 9153 is used to install the upper magnet 913; the precision threaded through hole 9154 is used to determine the position of the precision threaded knob 911. The first optical fiber sample 81 is placed in the V-groove 9122 and the pigtail passes through the fiber hole 9126, the silicone gasket 914 is adhered to the silicone gasket fixing hole 9152, and the pressure foot 915 is installed on the base 912 through the pressure foot fixing hole 9151 and the shaft fixing hole 9121; the precision threaded knob 911 is installed in the precision threaded through hole 9154, when the pressure foot 915 is buckled, the front end of the precision threaded knob 911 can be pressed against the precision threaded top screw slot 9124, and the silicone gasket 914 is pressed on the first optical fiber sample 81; the upper magnet 913 is installed in the upper magnet fixing hole 9153, and the lower magnet 916 is installed in the lower magnet fixing hole 9123. The upper magnet 913 and the lower magnet 916 provide clamping force between the base 912 and the pressure foot 915 through magnetic force; the base fixing shaft 9125 is installed on the first coaxial adjustment and alignment module 11. The structure of the second adjustable magnetic clamp 92 is the same as that of the first adjustable magnetic clamp 91 .

[0030] 4) The first coaxial adjustment and alignment module 11 includes a first five-dimensional adjustment frame 111 and a first adjustment frame adapter plate 112; the first five-dimensional adjustment frame 111 is fixed to the first adjustment frame adapter plate 112 with screws, and the first adjustable magnetic clamp 91 clamps and fixes the first optical fiber sample 81 and is installed on the first five-dimensional adjustment frame 111. The first five-dimensional adjustment frame 111 can adjust the pitch, horizontal, yaw, front and back and vertical states of the first optical fiber sample 81; the second coaxial adjustment and alignment module 12 includes a second five-dimensional adjustment frame 121, a second adjustment frame adapter plate 122, a precision The displacement slide 125 and the precision lifting platform 126; the precision displacement slide 125 is composed of a displacement guide rail 1251, a displacement slider 1252 and a displacement adjustment knob 1253; the precision lifting platform 126 is composed of a lifting platform 1261, a lifting platform base 1262 and a lifting adjustment knob 1263; the second five-dimensional adjustment frame 121 is fixed to the second adjustment frame adapter plate 122 with screws, the second adjustable magnetic clamp 92 clamps and fixes the second optical fiber sample 82 and is installed on the second five-dimensional adjustment frame 121, and the second five-dimensional adjustment frame 121 can adjust the second optical fiber sample 82's pitch, horizontal, yaw, front and back and vertical states; the second adjustment frame adapter plate 122 is connected to the displacement slider 1252; the displacement slider 1252 is placed on the displacement guide rail 1251, and the second five-dimensional adjustment frame 121 can be moved horizontally by adjusting the displacement adjustment knob 1253 to control the spacing of the optical fibers on both sides; the displacement guide rail 1251 is fixed on the lifting platform 1261, and the lifting platform 1261 moves the second five-dimensional adjustment frame 121 vertically by the lifting adjustment knob 1263, and the lifting platform 1261 is fixed to the large lifting platform base 562 On the marble platform 7; the first coaxial adjustment and alignment module 11 and the second coaxial adjustment and alignment module 12 both have five-dimensional adjustment functions of pitch, yaw, horizontal, vertical and front and back, which can accurately adjust the five-dimensional position of the optical fiber sample; the first coaxial adjustment and alignment module 11 adjusts the position of the first optical fiber sample 81 so that it is coaxial with the rotating main shaft 141; the second coaxial adjustment and alignment module 12 adjusts the position of the second optical fiber sample 82 so that it is coaxial with the first optical fiber sample 81, that is: the rotating main shaft 141, the first optical fiber sample 81 and the second optical fiber sample 82 are in a coaxial state.

[0031] 5) The angle rotation and measurement module includes an angle rotation module 13 and an angle rotation measurement module 14; the angle rotation module 13 is composed of a rotating motor 131, a motor fixing plate 132, and a coupling 133. The rotating motor 131 is fixed to the motor fixing plate 132 by screws, and the motor fixing plate 132 is fixed to the marble platform 7 by screws. The right side of the rotating motor 131 is connected to the angle rotation measurement module 14 through the coupling 133; the angle rotation measurement module 14 is composed of a rotating spindle 141, a code disk 142, a photoelectric encoder 143, a precision bearing A144, and a precision bearing B , bearing cover A145, bearing cover B146, bearing seat frame 147, the bearing seat frame 147 is composed of bearing support vertical plate A, bearing support vertical plate B and fixed base plate; the bearing mounting position A and bearing mounting position B of the rotating main shaft 141 are respectively installed on the bearing seat A and bearing seat B of the bearing support vertical plate A and bearing support vertical plate B through precision bearings A144 and precision bearings B, and are installed and fixed by bearing cover A145 and bearing cover B146; the bearing support vertical plate A and bearing support vertical plate B are installed on the fixed base plate at the same time, and the fixed base plate is fixed to the marble platform 7 by screws. On the left end of the rotating spindle 141 is connected to the rotating motor 131 through the coupling 133; the right end 148 of the rotating spindle is directly connected and fixed to the first coaxial adjustment and alignment module 11 through the adapter hole 1121, and the rotating spindle 141 can realize fixed-axis rotation. The first optical fiber sample 81 is coaxial with the rotating spindle 141, and the rotating motor 131 drives the rotating spindle 141, the first coaxial adjustment and alignment module 11, the first adjustable magnetic force 91 and the first optical fiber sample 81 to rotate synchronously through the coupling 133; the code disk 142 is mounted on the code disk fixed vertical plate of the rotating spindle 141, and the code disk 142 rotates The axis is coaxial with the rotating main shaft 141, and the two can rotate coaxially; the photoelectric encoder 143 is installed on the photoelectric encoder mounting hole, and the rotation angle of the first optical fiber sample 81 can be accurately measured through the code disk 142; the code disk 142 is fixed to the bearing support vertical plate A through the code disk fixing hole in the code disk mounting hole; the photoelectric encoder 143 is installed on the code disk 142 through the photoelectric encoder mounting hole, and is fixed to the bearing support vertical plate A through screws; the bearing support vertical plate A is fixed to the marble platform 7 through screws; the code disk 142, the precision bearing A14, and the precision bearing B are coaxial with the rotating main shaft 141.

[0032] 6) The binocular vision system module consists of a microscope fixing frame 102, a vertical plate 103, a hand wheel 104, a base 105, a threaded rod 106, a sliding rod 107, a baffle 108, a knob 109, a fixing frame moving block 1010, a lifting frame 1011, a central support 1012, and a first microscope 1013 and a second microscope 1014; the first microscope 1013 and the second microscope 1014 are in a vertical state, and the alignment state of the optical fiber can be observed from both horizontal and vertical directions; the first microscope 1013 and the second microscope 1014 are respectively mounted on the slide bar of the fixing frame moving block 1010, and the fixing frame moving block 1010 is mounted on the central support 1012 through the lifting frame 1011 012, the central support 1012 is mounted on the vertical plate 103 through the sliding rod 107, the vertical plate 103 is mounted on the marble platform 7 through the base 105, and the handwheel 104 is mounted on the central support 1012 through the threaded rod 106; the first microscope 1013 and the second microscope 1014 can both achieve three-dimensional adjustment, including horizontal (parallel to the optical fiber axis), vertical (perpendicular to the optical fiber axis) and forward and backward movement (parallel to the microscope axis), and the first microscope 1011 and the second microscope 1012 can achieve simultaneous and synchronous movement along the axis direction of the aligned optical fiber by manipulating their respective knobs 109 and pushing and pulling their respective microscope fixing frames 102 to slide on the fixing frame moving block 1010.

[0033] In the present invention, the process of making the optical fiber sample 8 is as follows:

[0034] 1) Cut multiple sections of Panda-type polarization-maintaining optical fiber, with a length greater than 10m.

[0035] 2) Immerse one end of the optical fiber in a chemical solution for a length of more than 30 cm to remove the coating. After the coating is stripped off, cut the bare fiber portion of the optical fiber to ensure that the cut end face is neat.

[0036] 3) After connecting the two ends of the uncoated optical fiber to a 0° polarizer and a 45° analyzer, respectively, the optical coherence domain polarimeter (OCDP) 6 is connected to measure its polarization crosstalk to observe whether abnormal crosstalk is introduced at the uncoated position. If abnormal crosstalk is present, the optical fiber is discarded and a new optical fiber is selected for re-production; if no abnormal crosstalk is present, proceed to the next step.

[0037] 4) After preparing multiple stripped optical fibers, prepare a first thin glass tube 812, a second thin glass tube 813, and a thick glass tube 814. Place the first thin glass tube 812 and the second thin glass tube 813 over the optical fiber coating. The glass tube closest to the stripped optical fiber should be 3 mm away from the stripped optical fiber. The spacing between the first thin glass tube 812 and the second thin glass tube 813 should be sufficient for bonding the thick glass tube 814. After placing the first thin glass tube 812 and the second thin glass tube 813, they are secured to the optical fiber coating with adhesive. Then, center the thick glass tube 814 over the first thin glass tube 812 and the second thin glass tube 813, applying adhesive to the adhesive area to secure the thick glass tube 814.

[0038] 5) After the first thin glass tube 812, the second thin glass tube 813, and the thick glass tube 814 are fixed, the optical fiber is connected to the 0° polarizer and the 45° analyzer again, and connected to the OCDP test to observe whether abnormal crosstalk is introduced at the coating removal position. If abnormal crosstalk is introduced, the optical fiber is discarded. If there is no abnormality, the polarizer and analyzer are removed, and the optical fiber sample is completed.

[0039] In the present invention, the thick glass tube 814 is bonded to the first thin glass tube 812 and the second thin glass tube 813, and the edge of the cladding must be kept at a distance of more than 1 mm from the first thin glass tube 812 and the second thin glass tube 813; each section of polarization-maintaining optical fiber can be 2 meters long, and its own polarization crosstalk coefficient is better than 40dB@1000m; the length of the first thin glass tube 812 and the second thin glass tube 813 are both 5 mm, and the length of the thick glass tube 814 is 10 mm.

[0040] In the present invention, the low stress magnetic fixture is installed and debugged as follows Figure 3 The specific steps are as follows:

[0041] 1. The presser foot 915 is mounted on the base 912 through the presser foot fixing hole 9151 and the shaft fixing hole 9121.

[0042] 2. The precision thread knob 911 is installed on the precision thread through hole 9154. When the presser foot is buckled, the front end of the precision thread knob 911 can press against the precision thread top screw notch 9124.

[0043] 3. Place the qualified first optical fiber sample 81 into the V-groove 9122, with the thick glass tube 814 protruding 1.5 mm relative to the V-groove 9122; pass the pigtail through the fiber hole 9126, and adjust the precision threaded knob 911 so that the pressure foot 915 does not touch the first optical fiber sample 81 immediately when it is buckled; the upper magnet 913 and the lower magnet 916 provide clamping force between the base 912 and the pressure foot 915 through magnetic force; rotate the precision threaded knob 911 to finely adjust the distance between the pressure foot 915 and the base 912 so that it just clamps the first optical fiber sample 81, thereby achieving low-stress clamping of the first optical fiber sample 81.

[0044] In the present invention, the microscope debugging and installation method is as follows Figure 4 The specific steps are as follows:

[0045] 1. Fasten the vertical plate 103 to the base 105 using M6 screws through the countersunk screw holes on the bottom of the base plate.

[0046] 2. Fix the base 105 to the marble table 7 with three pairs of M10 screws.

[0047] 3. Install the sliding rod 107 and the threaded rod 106 while installing the central support 1012, and finally install the handwheel 104.

[0048] 4. After installing the lifting frame 1011 and the fixed frame moving block 1010 on the central support 1012 using the buckle, install the microscope fixed frame 102 on the sliding bar of the fixed frame moving block 1010 and secure it with the blocking piece 108.

[0049] In the present invention, the five-dimensional adjustment frame is installed and debugged as follows Figure 5 The specific steps are as follows:

[0050] 1. Install the two adjustment racks on the adjustment rack adapter plate respectively, and tighten them in two directions with M3 screws to fix the five-dimensional adjustment rack, and make the first five-dimensional adjustment rack 111 and the second five-dimensional adjustment rack 121 parallel to each other and perpendicular to the ground.

[0051] 2. Adjust the lifting adjustment knob 1263 of the precision lifting platform 126 and the displacement adjustment knob 1253 of the precision displacement slide 125 so that the first five-dimensional adjustment frame 111 and the second five-dimensional adjustment frame 121 are on the same horizontal line.

[0052] 3. Adjust the vertical, horizontal, pitch, yaw, and front-back adjustment knobs respectively to gradually adjust the posture of the first optical fiber sample 81 and the second optical fiber sample 82 to a horizontal state, and observe the optical fiber alignment state under a microscope until they are fully aligned.

[0053] In the present invention, the design dimensions of each mechanical structure and the parameters of each component are selected as follows:

[0054] 1. The optical fibers used in the first optical fiber sample 81 and the second optical fiber sample 82 are both Panda-type polarization-maintaining optical fibers with a diameter of 125 μm.

[0055] 2. The displacement of displacement guide rail 1251 is 20mm, and the sliding table size is 60*60mm 2 It uses linear ball guides and has a body cover. The main material is stainless steel that has been electroless nickel-plated. It weighs 0.87kg, has a single positioning accuracy of 5μm, a repeat positioning accuracy of ±0.5μm, and a parallelism of 15μm.

[0056] 3. Precision lifting table 126 has a stroke of 60mm, a table size of 120*80mm, is driven by a precision-ground screw pair, has a resolution of 0.01mm, a load of 20kg, and a deadweight of 1.15kg.

[0057] 4. The first and second adjustable magnetic fixtures 91 and 92 are machined components, 30 mm long, 20 mm wide, and 13 mm high. The V-shaped notches etched into the fixture bases have a diameter of 4.24 mm and can hold the first and second optical fiber samples 81 and 82, which are bonded to thick glass tubes.

[0058] 5. The main body thickness of the first five-dimensional adjustment frame 111 and the second five-dimensional adjustment frame 121 is 16 mm, the width is 60 mm, and the height is 45 mm. The knob adjustment resolution is better than 1 μm.

[0059] In the present invention, a microscope is used to observe the alignment state of the optical fiber sample, and the first five-dimensional adjustment frame 111 and the second five-dimensional adjustment frame 121 are adjusted to align the optical fiber samples with each other in pitch, yaw, front and back, vertical and horizontal states. The rotation motor 131 is turned on and the photoelectric encoder 143 records the rotation angle.

[0060] In the present invention, when the first optical fiber sample 81 and the second optical fiber sample 82 are rotated relative to the axis, if the total incident polarized light intensity is I0 and the optical fiber relative to the axis angle is α, the uncoupled light energy I t The light energy I coupled to the c Can be expressed as:

[0061] I t =I0·cos 2 α, I c =I0·sin 2 α.

[0062] The optical fiber polarization extinction ratio PER is expressed logarithmically as:

[0063]

[0064] The above formula can be used to know the conversion method between the rotation angle of the first optical fiber sample 81 and the second optical fiber sample 82 and the extinction. After each functional module is installed as required, the ultra-high extinction ratio can be controlled by using the low-stress clamping optical fiber method, and the error in the extinction ratio caused by the stress on the optical fiber itself due to the rotation angle of the optical fiber can be eliminated.

Claims

1. A low-stress optical fiber clamping and alignment device for ultra-high polarization extinction ratio generation, characterized in that The device includes an optical fiber sample module, an optical fiber adjustable magnetic clamping module, a binocular vision system module, a coaxial adjustment and alignment module, and an angle rotation and measurement module, wherein: The optical fiber sample module includes a first optical fiber sample and a second optical fiber sample having the same structure; The optical fiber adjustable magnetic clamping module includes a first adjustable magnetic clamp and a second adjustable magnetic clamp with the same structure; The coaxial adjustment and alignment module includes a first coaxial adjustment and alignment module and a second coaxial adjustment and alignment module, and the first coaxial adjustment and alignment module and the second coaxial adjustment and alignment module both have five-dimensional adjustment functions of pitch, yaw, horizontal, vertical and front and back; The first optical fiber sample is clamped on a first adjustable magnetic clamp, the first adjustable magnetic clamp is mounted on a first coaxial adjustment and alignment module, and the first coaxial adjustment and alignment module is mounted on the angle rotation and measurement module; The second optical fiber sample is clamped on a second adjustable magnetic clamp, and the second adjustable magnetic clamp is mounted on a second coaxial adjustment and alignment module; The binocular vision system module observes the alignment status of the first optical fiber sample and the second optical fiber sample from both horizontal and vertical directions; The first optical fiber sample consists of a polarization-maintaining optical fiber, a first thin glass tube, a second thin glass tube, and a thick glass tube. The first thin glass tube and the second thin glass tube are bonded to the outside of the polarization-maintaining optical fiber with a spacing of 3 mm, and the thick glass tube is bonded to the outside of the first thin glass tube and the second thin glass tube in the middle. The second optical fiber sample has the same structure as the first optical fiber sample; The binocular vision system module, the second coaxial adjustment and alignment module, and the angle rotation and measurement module are fixed on a marble table.

2. The optical fiber low-stress clamping and alignment device for generating an ultra-high polarization extinction ratio according to claim 1, characterized in that The first adjustable magnetic clamp consists of a precision threaded knob, a base, an upper magnet, a silicone gasket, a pressure foot, and a lower magnet. The base is provided with a rotating shaft fixing hole, a V-shaped fixing groove, a lower magnet fixing hole, a precision threaded top screw slot, a base fixing shaft and a fiber passing hole; the pressure foot includes a pressure foot fixing hole, a silicone gasket fixing hole position, an upper magnet fixing hole, and a precision threaded through hole; the first optical fiber sample is placed in the V-shaped fixing groove and the pigtail passes through the fiber passing hole, the silicone gasket is adhered to the silicone gasket fixing hole position, and the pressure foot is mounted on the base through the pressure foot fixing hole and the rotating shaft fixing hole; the precision threaded knob is mounted in the precision threaded through hole, and when the pressure foot is buckled, the front end of the precision threaded knob can be pressed against the precision threaded top screw slot, and the silicone gasket is pressed on the first optical fiber sample; the upper magnet is mounted in the upper magnet fixing hole, and the lower magnet is mounted in the lower magnet fixing hole, and the upper magnet and the lower magnet provide clamping force between the base and the pressure foot through magnetic force; The base fixed shaft is installed on the first coaxial adjustment and alignment module.

3. The optical fiber low-stress clamping and alignment device for generating an ultra-high polarization extinction ratio according to claim 1, characterized in that The first coaxial adjustment and alignment module includes a first five-dimensional adjustment frame and a first adjustment frame adapter plate; the first five-dimensional adjustment frame is fixed on the first adjustment frame adapter plate, the first adjustable magnetic clamp clamps and fixes the first optical fiber sample, and is installed on the first five-dimensional adjustment frame, and the first five-dimensional adjustment frame can adjust the pitch, horizontal, yaw, front and back and vertical states of the first optical fiber sample 81; the second coaxial adjustment and alignment module includes a second five-dimensional adjustment frame, a second adjustment frame adapter plate, a precision displacement slide and a precision lifting platform; the precision displacement slide consists of a displacement guide rail, a displacement slider and a displacement adjustment knob; the precision lifting platform consists of a lifting platform surface, a lifting platform base and a lifting adjustment knob Composition: The second five-dimensional adjustment frame is fixed on the second adjustment frame adapter plate, the second adjustable magnetic clamp clamps and fixes the second optical fiber sample, and is installed on the second five-dimensional adjustment frame. The second five-dimensional adjustment frame can adjust the pitch, horizontal, yaw, front and back, and vertical states of the second optical fiber sample; the second adjustment frame adapter plate is connected to the displacement slider; the displacement slider is placed on the displacement guide rail, and the second five-dimensional adjustment frame is moved horizontally by adjusting the displacement adjustment knob to control the spacing between the optical fibers on both sides; the displacement guide rail is fixed on the lifting table, and the lifting table moves the second five-dimensional adjustment frame vertically through the lifting adjustment knob, and the lifting table is fixed on the marble platform through the lifting table base.

4. The optical fiber low-stress clamping and alignment device for generating an ultra-high polarization extinction ratio according to claim 1, characterized in that The angle rotation and measurement module includes an angle rotation module and an angle rotation measurement module; the angle rotation module is composed of a rotating motor, a motor fixed vertical plate, and a coupling, the rotating motor is fixed on the motor fixed vertical plate, the motor fixed vertical plate is fixed on the marble platform, and the right side of the rotating motor is connected to the angle rotation measurement module through a coupling; the angle rotation measurement module is composed of a rotating spindle, a code disk, a photoelectric encoder, a precision bearing A, a precision bearing B, a bearing cover A, a bearing cover B, and a bearing seat frame, and the bearing seat frame is composed of a bearing support vertical plate A, a bearing support vertical plate B and a fixed base plate; the bearing mounting position A and the bearing mounting position B of the rotating spindle are connected by precision bearings A and precision bearings B. They are respectively installed on the bearing seat A and bearing seat B of the bearing support vertical plate A and the bearing support vertical plate B, and are fixed by the bearing cover A and the bearing cover B; the bearing support vertical plate A and the bearing support vertical plate B are simultaneously installed on the fixed base plate, and the fixed base plate is fixed on the marble platform; the left end of the rotating spindle is connected to the rotating motor through a coupling, and the right end of the rotating spindle is connected and fixed to the first coaxial adjustment and alignment module; the code disk is installed on the code disk fixed vertical plate of the rotating spindle, and is fixed to the bearing support vertical plate A through the code disk mounting hole; the photoelectric encoder is installed on the code disk through the photoelectric encoder mounting hole and is fixed to the bearing support vertical plate A; the bearing support vertical plate A is fixed on the marble platform.

5. The optical fiber low-stress clamping and alignment device for generating an ultra-high polarization extinction ratio according to claim 1, characterized in that The binocular vision system module consists of a microscope fixing frame, a vertical plate, a handwheel, a base, a threaded rod, a sliding rod, a baffle, a fixing frame moving block, a lifting frame, a central support, and a first microscope and a second microscope; the first microscope and the second microscope are in a vertical state and are respectively installed on the sliding bars of the fixing frame moving block, the fixing frame moving block is installed on the central support through the lifting frame, the central support is installed on the vertical plate through the sliding rod, the vertical plate is installed on the marble platform through the base, and the handwheel is installed on the central support through the threaded rod.

6. The optical fiber low-stress clamping and alignment device for generating an ultra-high polarization extinction ratio according to claim 1, characterized in that The optical fibers used in the first optical fiber sample and the second optical fiber sample are both Panda-type polarization-maintaining fibers with a fiber diameter of 125µm.

7. The optical fiber low-stress clamping and alignment device for generating an ultra-high polarization extinction ratio according to claim 6, characterized in that The production process of the first optical fiber sample and the second optical fiber sample is as follows: 1) Cut multiple sections of Panda-type polarization-maintaining optical fiber with a length greater than 10m; 2) Immerse one end of the optical fiber in a chemical solution for a length of more than 30 cm to remove the coating. After the coating is stripped off, cut the bare fiber portion to ensure a neat cut end face. 3) Connect the two ends of the uncoated optical fiber to a 0° polarizer and a 45° analyzer, respectively, and then connect it to the OCDP to measure its polarization crosstalk. Observe whether abnormal crosstalk is introduced at the uncoated position. If abnormal crosstalk is present, discard the optical fiber and select a new optical fiber for re-production. If there is no abnormal crosstalk, proceed to the next step. 4) After making multiple uncoated optical fibers, prepare a first thin glass tube, a second thin glass tube, and a thick glass tube. Place the first thin glass tube and the second thin glass tube on the optical fiber coating. After the first thin glass tube and the second thin glass tube are placed, they are fixed to the optical fiber coating with adhesive. Then, place the thick glass tube centrally over the first thin glass tube and the second thin glass tube, and apply adhesive to the adhesive to secure the thick glass tube. 5) After the first thin glass tube, the second thin glass tube, and the thick glass tube are fixed, the optical fiber is reconnected to the 0° polarizer and the 45° analyzer, and then connected to the OCDP test to observe whether abnormal crosstalk is introduced at the coating removal position. If abnormal crosstalk is introduced, the optical fiber is discarded. If there is no abnormality, the polarizer and analyzer are removed, and the optical fiber sample is completed.

8. The optical fiber low-stress clamping and alignment device for generating an ultra-high polarization extinction ratio according to claim 7, characterized in that The thick glass tube is bonded to the first and second thin glass tubes, and the edge of the cladding must be kept at a distance of more than 1 mm from the first and second thin glass tubes; the polarization crosstalk coefficient of each section of polarization-maintaining optical fiber itself is better than 40 dB@1000 m; the lengths of the first and second thin glass tubes are both 5 mm, and the length of the thick glass tube is 10 mm.

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