Optical fiber coupler
By designing a lens mount and focusing nut separation structure, a wave spring, and a self-lubricating coating, the problems of optical axis misalignment and excessive friction during the focusing process of existing fiber optic couplers are solved, achieving a simple, stable, and precise beam coupling effect.
Patent Information
- Application Number
- CN202520898008.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-08
- Publication Date
- 2026-03-20
- Estimated Expiration
- 2035-05-08
AI Technical Summary
Existing fiber optic couplers/collimators are prone to problems such as optical axis misalignment, lens mount rotation, excessive friction, uneven adjustment, complex structure, large size, difficulty in integration, and poor repeatability during focusing.
The lens mount and focusing nut are separated. Combined with wave springs and self-lubricating coating, the lens maintains a fixed orientation during focusing through the precise fit between the side set screw and the long slot. The self-lubricating coating reduces friction and improves focusing smoothness and repeatability.
It achieves a simple structure, low cost, high stability, high focusing accuracy, and good repeatability, avoids optical axis deviation, improves coupling stability and beam alignment accuracy, and reduces return error.
Smart Images
Figure CN224020021U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of fiber optic coupler technology, specifically a fiber optic coupler. Background Technology
[0002] An optical fiber coupler is an optical device that couples a laser beam propagating in free space into an optical fiber, or conversely, converts diverging light output from an optical fiber into a parallel beam propagating in free space. This device is widely used in optical experiments.
[0003] Most existing couplers / collimators use the following types:
[0004] One method involves adjusting the focal length by rotating a threaded lens mount. During focusing, the lens rotates along with the lens, causing the optical axis to deflect. When used as a coupler, this can easily lead to loss of laser coupling; when used as a collimator, the output beam direction can change. A typical example is the Thorlabs Adjustable Aspheric Collimators CFC8A-B.
[0005] One approach utilizes approximately three threaded spring levers to simultaneously adjust both focus and orientation. However, in practice, the spring levers can generally only be adjusted sequentially, inevitably causing rotation of the lens's optical axis during focusing. Due to the use of multiple spring levers, this design's structure and manufacturing are far more complex than our invention. Typical examples include Thorlabs' fiberPort collimator / coupler PAF2-A7A and Daheng Optoelectronics' GCX-C18PC-B.
[0006] One approach involves mounting the lens on a one-dimensional translation stage. This method ensures that the lens does not rotate during focusing and allows for highly precise adjustment without backlash. However, this design typically has a large size, is difficult to integrate, and increases cost. A typical device is a fiber coupler cobbled together from Fiber Launch Systems' MBT621D / M and Thorlabs' z-translation stage SM1ZA.
[0007] One method involves a cylindrical lens mount that fits tightly into the coupler body. Focusing is not achieved through threads, but rather by using a tool similar to a flathead wrench to move the lens mount. This method results in extremely uneven focusing and very poor repeatability. A typical device is... +Kirchhoff Fiber Collimator Series 60FC.
[0008] However, the existing coupler / collimator technologies mentioned above have many problems. First, in some existing couplers / collimators, the lens may rotate with the nut during focusing, causing optical axis misalignment and affecting coupling efficiency. Second, in some existing couplers / collimators, the lens mount is prone to rotation during adjustment, thus affecting beam alignment accuracy. Moreover, some existing couplers / collimators use ordinary springs, which have a short fatigue life and may lead to a decrease in focusing accuracy after prolonged use. Furthermore, traditional focusing mechanisms often suffer from excessive friction, uneven adjustment, and even hysteresis errors, affecting repeatability. They also have problems such as cumbersome adjustment process, complex structure, large size, difficulty in integration, and poor repeatability. Utility Model Content
[0009] The purpose of this invention is to provide an optical fiber coupler to solve the problems mentioned in the background art.
[0010] The technical solution adopted in this utility model is as follows:
[0011] An optical fiber coupler includes a coupler body, a lens mount inside the coupler body, a focusing nut screwed to the rear end of the coupler body, a spring sleeved at the front end of the lens mount, an elongated slot on the side of the lens mount, and a set screw screwed to the side of the coupler body, the lower end of which is slidably inserted into the elongated slot.
[0012] Preferably, the lens mount is equipped with a lens and is fixed by a lens retainer.
[0013] Preferably, the lens is mounted at the center of the front end of the lens mount, and the lens retaining ring is screwed onto the lens mount.
[0014] Preferably, the spring is a wave spring.
[0015] Preferably, the contact surface between the focusing nut and the lens mount is provided with a self-lubricating coating.
[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are:
[0017] 1. In this utility model, the structure is simple, the processing is simple and the cost is low, and the stability is high. The structure of separating the lens seat and the focusing nut makes the lens always maintain a fixed direction during the focusing process, thereby avoiding optical axis deviation and improving coupling stability.
[0018] 2. In this utility model, a precise fit between the side set screw and the long slot is designed to effectively limit the rotational freedom of the lens mount, ensuring that the lens always moves along the axial direction during focusing, thereby further improving alignment accuracy and system stability.
[0019] 3. In this utility model, a high-elasticity, long-life wave spring is used, which not only ensures that the lens mount is always in a stable stress state, but also improves the durability and long-term reliability of the system, making the focusing operation smoother and the return error smaller.
[0020] 4. In this utility model, a self-lubricating coating is added to the contact surface between the focusing nut and the lens mount, which greatly reduces friction, makes focusing smoother, reduces return error, and improves the accuracy of repeated focusing. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the overall structure of this utility model;
[0022] Figure 2 This is an exploded view of the present invention;
[0023] Figure 3 This is a cross-sectional view of the present invention;
[0024] Figure 4 This is a schematic diagram illustrating the application effect of this utility model;
[0025] In the diagram: 1. Coupler body; 2. Lens mount; 21. Lens; 22. Lens retainer; 23. Long slot; 3. Focusing nut; 4. Spring; 5. Top screw; 01. Adjustable frame 1; 02. Coupler; 03. Adjustable frame 2; 04. Mirror; 05. Incident beam. Detailed Implementation
[0026] The specific embodiments of this utility model are described in detail below.
[0027] The "range" disclosed in this utility model is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values are listed as 1 and 2, and the maximum range values are listed as 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.
[0028] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.
[0029] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.
[0030] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.
[0031] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.
[0032] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.
[0033] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.
[0034] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.
[0035] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.
[0036] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.
[0037] Example:
[0038] A fiber optic coupler, such as Figure 1-3 As shown, it includes a coupler body 1, a lens seat 2 inside the coupler body 1, a focusing nut 3 screwed to the rear end of the coupler body 1, a spring 4 sleeved on the front end of the lens seat 2, a long slot 23 opened on the side of the lens seat 2, and a set screw 5 screwed to the side of the coupler body 1, with the lower end of the set screw 5 slidably inserted into the long slot 23.
[0039] In one possible implementation, the lens mount 2 is provided with a lens 21 and is fixed by a lens retainer 22.
[0040] In one possible implementation, the lens 21 is secured at the center of the front end of the lens mount 2, and the lens retainer 22 is screwed onto the lens mount 2.
[0041] In one possible implementation, spring 4 is a wave spring.
[0042] In one possible implementation, the contact surface between the focusing nut 3 and the lens mount 2 is provided with a self-lubricating coating.
[0043] Working principle, refer to Figure 1-3 The assembly of the collimator / coupler includes:
[0044] Install the spring 4 accurately into the coupling cavity at the front end of the coupler body 1 to ensure that the spring is subjected to uniform force.
[0045] The cylindrical lens mount 2 is securely installed into the coupling cavity at the front end of the coupler body, so that it forms a reasonable mechanical fit with the spring.
[0046] To prevent unnecessary rotation of the lens mount during operation, a side set screw 5 should be installed. During installation, it is important to ensure that the front end of the set screw precisely abuts against the pre-reserved slot in the cylindrical lens mount 2 to ensure a secure fixation.
[0047] Use the focusing nut 3 to tighten and adjust the cylindrical lens mount 2 so that the lens mount reaches the ideal optical alignment state.
[0048] The aspherical lens is mounted on the cylindrical lens mount 2 and securely fixed using lens clips, thus completing the assembly of the entire optical element. This assembly process requires precise mechanical and optical alignment of all components to ensure the stability and good optical performance of the entire system.
[0049] The implementation of the collimator function includes:
[0050] Installing optical fiber: Insert the FC / PC or FC / APC type optical fiber connector vertically into the optical fiber socket at the end of the main body, and rotate the nut of the FC optical fiber clockwise to fix the optical fiber head on the optical fiber socket;
[0051] Collimation Adjustment: The distance between the lens and the fiber optic head is precisely adjusted by rotating the nut, thus achieving the displacement of the lens in the beam propagation direction (axial direction). During adjustment, a long slot (2.1) on the lens mount engages with the side set screw to ensure that the lens mount does not rotate during focusing and to effectively limit radial rotation. The nut contact surface is coated with a PTFE composite coating to ensure smooth adjustment and reduce backlash error.
[0052] Output monitoring: In conjunction with a beam quality analyzer or CCD for real-time monitoring, stop rotating the focusing nut when the output spot diameter reaches the theoretical parallel light requirement.
[0053] Position locking: After completing the precision adjustment, tighten the side locking screw. During this process, the disc spring assembly continuously provides a preload of 5-8N, effectively compensating for mechanical backlash; the three-point positioning structure ensures that the lens mount remains stable under vibration (≤5Grms, where G is the acceleration due to gravity).
[0054] Important note: Loosen the locking screw before making repeated adjustments.
[0055] like Figure 4 As shown, the implementation of the coupler function includes:
[0056] To efficiently couple a free-space beam into an optical fiber, precise adjustments to the beam's propagation direction and position are required, typically involving five degrees of freedom. Figure 4 The adjustment of [a]-(e)]. These degrees of freedom can be achieved through components such as focusing nuts, adjustable frames, and mirrors. The specific steps are as follows:
[0057] Install the fiber optic cable: Insert the FC / PC or FC / APC type fiber optic connector vertically into the fiber optic socket at the tail end of the main body, and rotate the FC fiber optic nut clockwise to secure the fiber optic head to the fiber optic socket; then install coupler 02 on the adjustable pitch optical lens, see [link to installation instructions]. Figure 4 Adjustable frame No. 1, 01.
[0058] Adjusting the distance between the collimating lens and the fiber optic head (a): This distance determines the focusing effect of the beam and is crucial to coupling efficiency. During use, the lens position is changed by rotating the focusing nut to achieve optimal focusing at the fiber optic input.
[0059] Adjusting the pitch angle of the incident beam 05: The pitch angle refers to the deflection angle of the incident beam 05 in the vertical plane. This is achieved by adjusting the reflector 04 on an adjustable mount in front of the coupler, thus changing the pitch angle of the incident beam 05 to ensure the beam enters the fiber coupler correctly. See... Figure 4 The second adjustable frame 03(b) in the picture.
[0060] Adjust the horizontal angle of the incident beam 05: The horizontal angle refers to the deflection angle of the incident beam 05 in the horizontal plane. This is also adjusted using the adjustable frame to ensure the beam propagates in the correct direction. See... Figure 4 The second adjustable frame 03(c) in the picture.
[0061] Adjusting the pitch angle of the coupler: This is done by adjusting the pitch knob on the coupler. Figure 4 The adjustable frame 01(d) is configured such that the incident beam 05 and the coupler 02 are in completely opposite directions.
[0062] Adjust the horizontal angle of coupler 02: by adjusting the horizontal knob of coupler 02 [ Figure 4 The adjustable frame 01(e) is configured such that the incident beam 05 and the coupler 02 are in completely opposite directions.
[0063] By finely adjusting the five degrees of freedom through the above steps, it can be ensured that the free-space beam is coupled into the optical fiber in the best way, thereby improving optical transmission efficiency and system stability.
[0064] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. An optical fiber coupler, characterized in that: The coupling body (1) includes a lens seat (2) inside the coupling body (1), a focusing nut (3) is screwed onto the rear end of the coupling body (1), a spring (4) is sleeved on the front end of the lens seat (2), a long slot (23) is opened on the side of the lens seat (2), and a set screw (5) is screwed onto the side of the coupling body (1), with the lower end of the set screw (5) slidingly inserted into the long slot (23).
2. The fiber optic coupler as described in claim 1, characterized in that: The lens mount (2) is provided with a lens (21) and is fixed by a lens retainer (22).
3. The fiber optic coupler as described in claim 2, characterized in that: The lens (21) is mounted at the center of the front end of the lens holder (2), and the lens retainer (22) is screwed onto the lens holder (2).
4. The fiber optic coupler as described in claim 1, characterized in that: The spring (4) is a wave spring.
5. The fiber optic coupler as described in claim 1, characterized in that: The contact surface between the focusing nut (3) and the lens mount (2) is provided with a self-lubricating coating.