All-glass single-mode polarization-maintaining optical fiber collimator and preparation method thereof

Abstract

The invention relates to the technical field of optical fiber communication and optical measurement, in particular to an all-glass single-mode polarization-maintaining optical fiber collimator and a preparation method thereof.The all-glass single-mode polarization-maintaining optical fiber collimator comprises a collimating lens, a glass sleeve, a quartz ferrule and a single-mode polarization-maintaining optical fiber which are sequentially arranged along an optical path; the collimating lens and the glass sleeve are bonded and fixed through an oxyhydrogen catalytic bonding solution; an optical fiber core of the single-mode polarization maintaining optical fiber extends into the quartz ferrule, and one end of the quartz ferrule extends into the glass sleeve and is bonded and fixed with the glass sleeve through an oxyhydrogen catalytic bonding solution; the optical fiber collimator is prepared into a full-glass structure, stable collimation performance is ensured, meanwhile, the hydrogen-oxygen catalytic bonding technology is adopted for bonding and fixing all parts of the optical fiber collimator, high-strength and glue-free bonding can be achieved, the problem of thermal instability caused by poor thermal conductivity is effectively avoided, and long-term stable optical performance is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber communication and optical measurement, and in particular relates to an all-glass single-mode polarization-maintaining optical fiber collimator and a preparation method thereof. Background Art

[0002] Fiber collimators are key components in fiber-optic communications, optical measurements, and other optical systems. They are mainly used to convert divergent light transmitted by optical fibers into collimated light, or to efficiently couple external parallel light into single-mode optical fibers. The performance of fiber collimators directly affects the efficiency and stability of the system, especially in high-precision measurement technologies such as laser interferometry, where the collimation effect is crucial to measurement accuracy. With the advancement of technology, the requirements for the accuracy and stability of fiber collimators are also increasing.

[0003] There are many solutions for realizing fiber collimators in the prior art, but there are still some problems that need to be solved. For example, the Chinese patent announcement number is CN218547048U, the announcement date is February 28, 2023, and the patent name is a utility model patent for "a fiber collimator". It uses a fiber collimator with a metal support structure to achieve beam collimation through optical lenses and mechanical adjustment. Although this design meets the basic collimation requirements, due to the different thermal expansion coefficients of metals and optical materials, thermal stress is easily generated when the temperature changes, resulting in unstable collimation performance, which in turn affects the overall accuracy of the system. In addition, metal structures are prone to thermal stress concentration in high temperature environments, affecting the long-term stability of the device.

[0004] There are also many fiber collimators that use glue to bond optical lenses, such as the utility model patent with Chinese patent announcement number CN217156863U, announcement date August 9, 2022, and patent name "A Glued Fiber Collimator", and the utility model patent with Chinese patent announcement number CN220040807U, announcement date November 17, 2023, and patent name "A Glued Fiber Collimator". Although the stability is improved to a certain extent by bonding, the glue has poor thermal conductivity and is prone to heat accumulation during long-term operation, which leads to system instability. The glue may also release volatile gases during the curing process, contaminating the surface of the optical component and affecting long-term reliability. Even if glue with better thermal conductivity is used, it still faces problems such as high cost and poor stability, and cannot meet the needs of high precision and high stability, especially in application fields with extremely high requirements for temperature stability and collimation accuracy, such as laser interferometry.

[0005] Based on the above problems, the main disadvantages of traditional fiber collimators include: the metal support structure is prone to thermal stress when the temperature changes, affecting the thermal stability of the system; the glue bonding method has poor thermal conductivity and is prone to mechanical stress changes, thereby reducing the stability of the collimator. Summary of the invention

[0006] In view of this, the invention aims to provide an all-glass single-mode polarization-maintaining fiber collimator and its preparation method, which uses hydrogen-oxygen catalytic bonding technology to bond and combine the all-glass fiber collimator, which not only improves the thermal stability of the collimator, but also ensures its high-precision performance in complex environments, and is particularly suitable for optical fiber communication, precision optical measurement, and high-precision laser interferometry. Its main features include high precision, high stability, low cost, high strength, and low thermal sensitivity.

[0007] To achieve the above object, the technical solution created by the present invention is implemented as follows: An all-glass single-mode polarization-maintaining optical fiber collimator comprises a collimating lens, a glass sleeve, a quartz ferrule and a single-mode polarization-maintaining optical fiber which are sequentially arranged along an optical path; wherein the collimating lens and the glass sleeve are bonded and fixed by a hydrogen-oxygen catalytic bonding solution; the optical fiber core of the single-mode polarization-maintaining optical fiber extends into the quartz ferrule, one end of the quartz ferrule extends into the glass sleeve and is bonded and fixed to the glass sleeve by a hydrogen-oxygen catalytic bonding solution.

[0008] Furthermore, at least one exhaust hole is provided on the glass sleeve.

[0009] Furthermore, a rubber protective sleeve is provided on the outer cover of the single-mode polarization-maintaining optical fiber.

[0010] Furthermore, a quartz glass support block is arranged between the rubber protective sleeve and the glass sleeve, the quartz ferrule passes through the quartz glass support block, and one end of the quartz glass support block extends into the gap between the rubber protective sleeve and the single-mode polarization-maintaining optical fiber; the other end of the quartz glass support block is bonded and fixed to the glass sleeve by a hydrogen-oxygen catalytic bonding solution.

[0011] Furthermore, an anti-reflection film is provided on the optical fiber end face close to the quartz ferrule in the single-mode polarization-maintaining optical fiber.

[0012] A method for preparing an all-glass single-mode polarization-maintaining optical fiber collimator, which is used to prepare the all-glass single-mode polarization-maintaining optical fiber collimator provided by the present invention, comprises the following steps: S1: Using hydrogen-oxygen catalytic bonding solution to bond and fix the collimating lens and the glass sleeve; S2: remove the outer shell of the single-mode polarization-maintaining optical fiber, and put a rubber protective sleeve on the outside of the single-mode polarization-maintaining optical fiber; S3: inserting the optical fiber core of the single-mode polarization-maintaining optical fiber of step S2 into the quartz ferrule, and then passing the quartz ferrule through the quartz glass support block; S4: inserting the quartz ferrule in step S3 into the glass sleeve in step S2, so that the quartz glass support block in step S3 is in contact with the glass sleeve; S5: using a detector to measure actual spot information of the structure formed in step S4, and adjusting the current structure according to the measured structure; S6: bonding and fixing the quartz ferrule and the glass sleeve in the structure formed in step S5 by means of a hydrogen-oxygen catalytic bonding solution, and bonding and fixing the quartz glass support block and the glass sleeve in the structure formed in step S5 by means of a hydrogen-oxygen catalytic bonding solution.

[0013] Furthermore, in step S1, the collimating lens and the glass sleeve are bonded and fixed by using 0.1 μl to 0.2 μl of hydrogen-oxygen catalytic bonding solution.

[0014] Furthermore, the molar concentration ratio of the hydrogen-oxygen catalytic bonding solution is 1:25-1:500.

[0015] Further, in step S4, the quartz ferrule and the optical fiber core inside the quartz ferrule extend into the glass sleeve from the rear end surface of the glass sleeve.

[0016] Furthermore, step S5 includes the following steps: S51: adjusting the position of the structure formed in step S4 so that the collimated light beam emitted by the structure formed in step S4 is directly input into the beam quality analyzer; S52: adjusting the position of the optical fiber end face of the optical fiber core, and using a detector to obtain the collimated beam waist radius, collimated beam waist position, collimated light spot diameter and collimated divergence angle of the collimated light beam output when the optical fiber end face is at different positions; S53: using a detector to measure the polarization state of the collimated light beam output by the current structure, and rotating and adjusting the current structure according to the current polarization state of the collimated light beam; S54: Repeat steps S52 to S53 until the collimated beam waist radius, collimated beam waist position, collimated light spot diameter, collimated divergence angle and collimated beam polarization state of the collimated beam currently output meet the design requirements.

[0017] Compared with the prior art, the invention can achieve the following beneficial effects: (1) The all-glass single-mode polarization-maintaining fiber collimator described in the invention adopts an all-glass structure, which avoids the problem of inconsistent thermal expansion coefficients of metal materials and optical lens materials, eliminates thermal stress in a temperature-changing environment, and ensures stable collimation performance; at the same time, the preparation method adopts hydrogen-oxygen catalytic bonding technology to complete bonding and fixing. Compared with traditional glue bonding, hydrogen-oxygen catalytic bonding technology can achieve high-strength, glue-free bonding, effectively avoid the thermal instability problem caused by poor thermal conductivity, and ensure long-term optical performance stability; (2) In the all-glass single-mode polarization-maintaining optical fiber collimator described in the present invention, the exhaust hole design enables it to maintain internal and external air pressure balance in a vacuum environment, ensuring the normal operation of the device in a vacuum state. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 A schematic diagram of the structure of the all-glass single-mode polarization-maintaining optical fiber collimator according to an embodiment of the present invention; Figure 2 A schematic cross-sectional view of the structure of the all-glass single-mode polarization-maintaining optical fiber collimator according to an embodiment of the present invention; Figure 3 A schematic diagram of the structure of the glass sleeve according to an embodiment of the present invention; Figure 4 A schematic flow chart of a method for preparing an all-glass single-mode polarization-maintaining optical fiber collimator according to an embodiment of the present invention; Figure 5 This is a schematic cross-sectional view of the structure after completing step S1 according to an embodiment of the present invention; Figure 6 This is a schematic cross-sectional view of the structure after completing step S2 according to an embodiment of the present invention; Figure 7 It is a schematic cross-sectional structure diagram after completing step S3 according to an embodiment of the present invention; Figure 8 A schematic diagram of step S4 described in an embodiment of the present invention; Fig. 9 It is a curve diagram showing the influence of the fiber end face position on the collimated beam waist radius and the collimated beam waist position; Fig.10 It is an influence curve diagram of the influence of the optical fiber end face position on the spot diameter after alignment; Fig.11 It is a curve diagram showing the influence of the optical fiber end face position on the beam divergence angle after alignment; Fig.12 This is a light spot morphology diagram of the all-glass single-mode polarization-maintaining fiber collimator described in the embodiment of the present invention in actual measurement; Fig.13 This is a measurement diagram of the actual light spot polarization state of the all-glass single-mode polarization-maintaining fiber collimator described in the embodiment of the present invention in actual measurement.

[0019] Description of reference numerals: 1. Collimating lens; 2. Glass sleeve; 3. Quartz ferrule; 4. Quartz glass support block; 5. Rubber protective cover; 6. Single-mode polarization-maintaining optical fiber; 7. Optical fiber core; 8. Exhaust hole; 9. Optical platform; 10. Lifting and translation stage; 11. Detector; 12. Clamp. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0023] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0024] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0025] like Figures 1 to 3 As shown, the all-glass single-mode polarization-maintaining fiber collimator described in the embodiment of the invention includes a collimating lens 1, a glass sleeve 2, a quartz ferrule 3, a quartz glass support block 4, a rubber protective cover 5 and a single-mode polarization-maintaining fiber 6.

[0026] The collimating lens 1 is fixed in the front end groove of the glass sleeve 2 by bonding with 0.1μl~0.2μl of hydrogen-oxygen catalytic bonding solution. Among them, the main function of the collimating lens 1 is to collimate the light beam from the outside. The collimating lens 1 can be a spherical lens or an aspherical lens, and the specific selection depends on the actual collimation requirements. The collimating lens 1 collimates the divergent light beam to make it parallel light, thereby reducing scattering in subsequent light transmission, improving the fiber coupling efficiency and the overall stability of the optical system. The glass sleeve 2 mainly supports and fixes the collimating lens 1, and can also fix the quartz ferrule 3 to ensure the accurate position of the fiber end face. The design of the glass sleeve 2 can not only provide stable support for the optical fiber, but also control the insertion depth of the optical fiber through its structural design, thereby adjusting the output quality of the collimated light beam.

[0027] The optical fiber core 7 of the single-mode polarization-maintaining optical fiber 6 extends into the quartz ferrule 3, one end of the quartz ferrule 3 extends into the glass sleeve 2, and is bonded and fixed to the glass sleeve 2 by a hydrogen-oxygen catalytic bonding solution. The quartz ferrule 3 is used to accurately fix the position of the optical fiber core 7, ensuring that the light beam can directly enter the collimating lens 1 from the optical fiber core 7. During the entire collimation process, the quartz ferrule 3 provides mechanical support and stability to prevent the optical fiber core 7 from shifting during operation or use; the single-mode polarization-maintaining optical fiber 6 preferably uses an optical fiber of model PMFP-1064-S-FC / APC-FC / APC-3.0-2M, which is used to transmit laser signals and can maintain the polarization state of the optical signal to avoid changes in the polarization state caused by external interference or optical fiber bending; in high-precision applications such as laser communication and optical measurement, the use of the single-mode polarization-maintaining optical fiber 6 greatly improves the optical signal transmission quality and stability of the system, ensuring the transmission consistency and accuracy of the signal.

[0028] The rubber protective sleeve 5 is sleeved on the outside of the single-mode polarization-maintaining optical fiber 6; the quartz glass support block 4 is placed between the rubber protective sleeve 5 and the glass sleeve 2. In the embodiment of the present invention, the quartz glass support block 4 is preferably set to a T-shaped structure, and the end of the quartz glass support block 4 with a smaller section radius extends into the rubber protective sleeve 5 and contacts the single-mode polarization-maintaining optical fiber 6, and the end of the quartz glass support block 4 with a larger section radius is bonded and fixed to the rear end face of the glass sleeve 2 through a hydrogen-oxygen catalytic bonding solution. Among them, the quartz glass support block 4 plays the role of auxiliary support of the rubber protective sleeve 5 and prevents the quartz ferrule 3 from being deformed by external extrusion; the main function of the rubber protective sleeve 5 is to provide protection for the single-mode polarization-maintaining optical fiber 6, prevent the single-mode polarization-maintaining optical fiber 6 from being affected by bending and mechanical stress, ensure that the single-mode polarization-maintaining optical fiber 6 is not damaged during the bending process, extend its service life, and maintain the stability of the optical signal transmitted in the single-mode polarization-maintaining optical fiber 6; at the same time, the rubber protective sleeve 5 also effectively reduces the influence of external environmental factors on the collimation performance of the single-mode polarization-maintaining optical fiber 6.

[0029] In the embodiment of the present invention, an exhaust hole 8 is provided on the surface of the glass sleeve 2. The exhaust hole 8 is designed to ensure the balance of air pressure inside and outside the glass sleeve 2 when used in a vacuum or closed environment. This structure can effectively prevent stress concentration caused by the difference in air pressure inside and outside, thereby avoiding deformation of the device or degradation of performance. At the same time, an anti-reflection film is provided on the fiber end face of the single-mode polarization-maintaining fiber 6 close to the quartz ferrule 3, which is set to 1064nm in the embodiment of the present invention.

[0030] The invention also provides a method for preparing an all-glass single-mode polarization-maintaining fiber collimator, which is used to prepare the all-glass single-mode polarization-maintaining fiber collimator described in the invention. To clearly explain the method for preparing the all-glass single-mode polarization-maintaining fiber collimator described in the invention, take the preparation of an all-glass single-mode polarization-maintaining fiber collimator with an operating wavelength of 1064nm, a collimated light beam waist diameter of about 2.7mm, a waist position within the range of 0 to 1700mm, and polarization state requirements of 0°±1° and 90°±1° as an example.

[0031] like Figures 4 to 8 As shown, the method for preparing the all-glass single-mode polarization-maintaining optical fiber collimator described in the embodiment of the present invention comprises the following steps: S1: Use hydrogen-oxygen catalytic bonding solution to bond and fix the collimating lens 1 and the glass sleeve 2. The stress-free bonding using this technology ensures high strength and low thermal stress during the bonding process, thereby ensuring the stability of the collimator under different temperature environments. In an embodiment of the present invention, the collimating lens 1 and the glass sleeve 2 are bonded and fixed by 0.1μl~0.2μl of hydrogen-oxygen catalytic bonding solution. This bonding method avoids the problem of thermal expansion differences caused by using traditional glue bonding, and improves the overall stability and accuracy of the device.

[0032] The molar concentration ratio of the hydrogen-oxygen catalytic bonding solution is 1:25-1:500. In the embodiment of the present invention, the optimal molar concentration ratio of the hydrogen-oxygen catalytic bonding solution is NaOH:H2O=1:300, and the optimal dosage is 0.4 μl / cm 2 To ensure the best bonding effect. The bonding process of hydrogen-oxygen catalytic bonding solution includes three stages: Hydration (or etching) stage: Hydroxygen catalyzes the hydroxide ions in the bonding solution to corrode the silicon dioxide surfaces of the collimating lens 1 and the glass sleeve 2, releasing silicate ions, i.e. ; Polymerization stage: As the active hydroxide ions in the hydrogen-oxygen catalytic bonding solution decrease, the pH value of the hydrogen-oxygen catalytic bonding solution gradually decreases; when the pH value drops below 11, the silicate ions dissociate to form silicate molecules, i.e. ; Subsequently, the silicic acid molecules undergo a polymerization reaction to form siloxane chains and water, i.e. ; Dehydration stage: The moisture in the bonding layer between the collimating lens 1 and the glass sleeve 2 gradually migrates or evaporates, the thickness of the bonding layer decreases, and the strength gradually increases; the entire bonding process can form initial strength within 1 to 3 minutes, and the bonding strength reaches the maximum after standing for one month, thus completing high-strength bonding.

[0033] The above content is an example of using hydrogen-oxygen catalytic bonding solution to bond and fix the collimating lens 1 and the glass sleeve 2. When the hydrogen-oxygen catalytic bonding solution is used to bond and fix the other two glass devices in the all-glass single-mode polarization-maintaining fiber collimator described in the embodiment of the invention, the bonding process of the hydrogen-oxygen catalytic bonding solution is the same, and the corresponding devices can be replaced, which will not be repeated below.

[0034] S2: Remove the outer shell of the single-mode polarization-maintaining optical fiber 6, and put the rubber protective sleeve 5 on the outside of the single-mode polarization-maintaining optical fiber 6. The rubber protective sleeve 5 can prevent the single-mode polarization-maintaining optical fiber 6 from being affected by external mechanical stress, especially control the bending radius of the optical fiber, avoid damage to the optical fiber, and avoid excessive bending of the optical fiber to affect the transmission efficiency.

[0035] S3: inserting the optical fiber core 7 of the single-mode polarization-maintaining optical fiber 6 in step S2 into the quartz ferrule 3, and then passing the quartz ferrule 3 through the quartz glass support block 4.

[0036] S4: insert the quartz ferrule 3 in step S3 into the glass sleeve 2 in step S2, so that the quartz glass support block 4 in step S3 contacts the glass sleeve 2. Specifically, the quartz ferrule 3 and the optical fiber core 7 inside the quartz ferrule 3 extend into the glass sleeve 2 from the rear end face of the glass sleeve 2.

[0037] S5: Use the detector 11 to measure the actual spot information of the structure formed in step S4, and adjust the current structure according to the measured structure. In the embodiment of the present invention, the optical platform 9 and the lifting and displacement stage 10 are used in cooperation to ensure that the light beam emitted by the current structure accurately enters the detector 11 mounted on the optical platform 9. Among them, the optical platform 9 provides a stable measurement environment for supporting the entire measurement system; the platform has good shock absorption and stability performance, and can reduce the impact of external vibration on optical measurement; the lifting and displacement stage 10 is mounted on the optical platform 10, and the current structure is fixed on the lifting and displacement stage 10 by the clamp 12. The lifting and displacement stage 10 adjusts the height of the current structure up and down to ensure that the light beam emitted by the current structure accurately enters the detector 11. This adjustment can be flexibly used under different measurement conditions to ensure the accuracy and precision of the measurement. The type of detector 11 can be adjusted according to actual needs. In the embodiment of the present invention, when the beam quality analyzer is used as the detector 11, it is used to measure the collimated beam waist radius, collimated beam waist position, collimated light spot diameter and collimated divergence angle of the collimated beam output by the structure formed in step S4; when the beam polarization state measurement polarimeter is used as the detector 11, it is used to measure the polarization state of the collimated beam output by the structure formed in step S4. Based on this, in the embodiment of the present invention, step S5 includes the following steps: S51: Using the lifting platform 10 to adjust the structure formed in step S4, so that the collimated light beam emitted by the structure formed in step S4 is directly input into the beam quality analyzer.

[0038] S52: adjusting the position of the optical fiber end face of the optical fiber core 7, the adjustment range is set to -0.02 mm to +0.02 mm, and using a beam quality analyzer to obtain the collimated beam waist radius, collimated beam waist position, collimated light spot diameter and collimated divergence angle of the collimated light beam output when the optical fiber end face positions are different; S53: replacing the beam quality analyzer with the beam polarization state measurement polarimeter, and using the beam polarization state measurement polarimeter to measure the polarization state of the collimated beam output by the current structure, and rotating and adjusting the current structure according to the current polarization state of the collimated beam; S54: Repeat steps S52 to S53 until the collimated beam waist radius, collimated beam waist position, collimated light spot diameter, collimated divergence angle and collimated beam polarization state of the collimated beam currently output meet the design requirements.

[0039] The measurement change process in step S5 is as follows: Figure 9~Figure 13 As shown. Among them, Fig. 9The influence curve of the fiber end position on the collimated beam waist radius and collimated beam waist position is shown, where the horizontal axis represents the adjustment amount of the fiber end position, the left side of the vertical axis represents the beam waist radius (unit: mm), and the right side represents the beam waist position (unit: mm). The solid line represents the change of the beam waist radius. As the fiber end is adjusted from -20μm to +20μm, the beam waist radius presents a peak value. When the adjustment amount of the fiber end position is about 0μm, the beam waist radius reaches the maximum value (about 1.36mm) and gradually decreases on both sides. The dotted line represents the change of the beam waist position. As the adjustment amount of the fiber end position is adjusted from -20μm to +20μm, the beam waist position gradually increases, showing a linear growth from -2500mm to +2500mm. This figure shows that the position adjustment of the fiber end will affect the focusing state of the beam, and the adjustment of the beam waist radius and the beam waist position are interrelated. Fig.10 The effect of the distance between the beam quality analyzer 11 and the optical fiber core 7 on the beam waist diameter at different fiber end face positions (from -0.020mm to +0.020mm) is shown. The horizontal axis represents the position distance of the beam quality analyzer 11 (unit: mm), and the vertical axis represents the beam waist diameter (unit: mm). Each curve represents a different adjustment amount of the fiber end face position, from -0.020mm to +0.020mm. When the fiber end face position is a negative value and a value of 0, the diameter of the beam entering the beam quality analyzer is large, and as the distance between the beam quality analyzer and the optical fiber core 7 increases, the beam diameter gradually increases and shows an upward trend. When the fiber end face position is a positive value, the diameter of the beam entering the beam quality analyzer is small, and as the distance between the beam quality analyzer and the optical fiber core increases, the beam diameter mainly shows a decreasing trend. In particular, when the fiber end face position is 0.010mm, the overall change in the spot diameter is very small (from 2.68mm to 2.76mm), which meets the design requirements. Fig.11 The effect of the fiber end face position adjustment on the divergence angle (unit: rad) is shown. The horizontal axis represents the position adjustment of the fiber end face, and the vertical axis represents the divergence angle (unit: rad). The image presents a symmetrical parabola shape, which shows that the positive and negative changes in the fiber end face position have a symmetrical effect on the beam divergence angle; when the fiber end face position is far away from the origin, the beam divergence angle will increase in both the positive and negative directions. The curve shows that when the fiber end face position changes within the range of ±20μm, the divergence angle increases from the minimum value of 2.3×10 −4 rad increases to nearly 2.7×10 −4 rad. When the fiber end face position is 0.010 mm, the divergence angle is very small, about 2.5×10 -4 rad.

[0040] S6: The quartz ferrule 3 and the glass sleeve 2 in the structure formed in step S5 are bonded and fixed by a hydrogen-oxygen catalytic bonding solution, and the quartz glass support block 4 in the structure formed in step S5 is bonded and fixed by a hydrogen-oxygen catalytic bonding solution. At this point, the preparation of the all-glass single-mode polarization-maintaining fiber collimator is completed.

[0041] Fig.12 The light spot morphology of the light output by the optical fiber collimator obtained by the preparation method of the all-glass single-mode polarization-maintaining optical fiber collimator described in the embodiment of the invention in actual measurement is shown. The measurement results of the light spot show that the light beam has a relatively concentrated and uniform intensity distribution, which meets the designed collimated beam characteristics. The light spot diameter is about 2.7mm, the waist position is 1312mm, the waist diameter is 2.7mm, and the collimation distance is about 4m. The light spot measurement results verify the efficient collimation ability of the all-glass single-mode polarization-maintaining optical fiber collimator, which can keep the light beam concentrated and stable within a certain distance. These measurement data show that the collimator is suitable for high-precision optical systems, especially in laser transmission and precision measurement, and has good application prospects. Fig.13 The actual spot polarization state of the light output by the optical fiber collimator obtained by the preparation method of the all-glass single-mode polarization-maintaining optical fiber collimator described in the embodiment of the invention is shown. Fig.13 (a) shows the propagation of the single-mode polarization-maintaining optical fiber 6 when the slow axis is parallel to the reference base plane of the glass sleeve 2. Its propagation pattern presents a horizontal line, indicating that the polarization direction of the light beam is mainly concentrated in the horizontal direction. Fig.13 (b) shows the propagation of the single-mode polarization-maintaining optical fiber 6 when the slow axis is perpendicular to the reference base plane of the glass sleeve 2. Its propagation pattern presents a vertical line, indicating that the polarization direction of the light beam is mainly concentrated in the vertical direction.

[0042] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0043] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An all-glass single-mode polarization-maintaining fiber collimator, characterized in that: It comprises a collimating lens, a glass sleeve, a quartz ferrule and a single-mode polarization-maintaining optical fiber which are sequentially arranged along an optical path; wherein the collimating lens and the glass sleeve are bonded and fixed by a hydrogen-oxygen catalytic bonding solution; the optical fiber core of the single-mode polarization-maintaining optical fiber extends into the quartz ferrule, one end of the quartz ferrule extends into the glass sleeve, and is bonded and fixed to the glass sleeve by the hydrogen-oxygen catalytic bonding solution.

2. The all-glass single-mode polarization-maintaining fiber collimator according to claim 1, characterized in that: No less than one exhaust hole is provided on the glass sleeve.

3. The all-glass single-mode polarization-maintaining optical fiber collimator according to claim 1, characterized in that: A rubber protective sleeve is provided on the outer cover of the single-mode polarization-maintaining optical fiber.

4. The all-glass single-mode polarization-maintaining optical fiber collimator according to claim 3, characterized in that: A quartz glass support block is arranged between the rubber protective sleeve and the glass sleeve, the quartz ferrule passes through the quartz glass support block, and one end of the quartz glass support block extends into the gap between the rubber protective sleeve and the single-mode polarization-maintaining optical fiber; the other end of the quartz glass support block is bonded and fixed to the glass sleeve through the hydrogen-oxygen catalytic bonding solution.

5. The all-glass single-mode polarization-maintaining fiber collimator according to claim 1, characterized in that: An anti-reflection film is provided on the optical fiber end face close to the quartz ferrule in the single-mode polarization-maintaining optical fiber.

6. A method for preparing an all-glass single-mode polarization-maintaining optical fiber collimator, used to prepare the all-glass single-mode polarization-maintaining optical fiber collimator as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1: using the hydrogen-oxygen catalytic bonding solution to bond and fix the collimating lens and the glass sleeve; S2: removing the outer shell of the single-mode polarization-maintaining optical fiber, and putting a rubber protective sleeve on the outside of the single-mode polarization-maintaining optical fiber; S3: inserting the optical fiber core of the single-mode polarization-maintaining optical fiber of step S2 into the quartz ferrule, and then passing the quartz ferrule through the quartz glass support block; S4: inserting the quartz ferrule in step S3 into the glass sleeve in step S2, so that the quartz glass support block in step S3 is in contact with the glass sleeve; S5: using a detector to measure actual spot information of the structure formed in step S4, and adjusting the current structure according to the measured structure; S6: bonding and fixing the quartz ferrule and the glass sleeve in the structure formed in step S5 by the hydrogen-oxygen catalytic bonding solution, and bonding and fixing the quartz glass support block and the glass sleeve in the structure formed in step S5 by the hydrogen-oxygen catalytic bonding solution.

7. The method for preparing the all-glass single-mode polarization-maintaining optical fiber collimator according to claim 6, characterized in that: In step S1, the collimating lens and the glass sleeve are bonded and fixed by using 0.1 μl to 0.2 μl of hydrogen-oxygen catalytic bonding solution.

8. The method for preparing the all-glass single-mode polarization-maintaining optical fiber collimator according to any one of claims 6 or 7, characterized in that: The molar concentration ratio of the hydrogen-oxygen catalytic bonding solution is 1:25-1:

500.

9. The method for preparing the all-glass single-mode polarization-maintaining optical fiber collimator according to claim 6, characterized in that: In step S4, the quartz ferrule and the optical fiber core inside the quartz ferrule extend into the glass sleeve from the rear end surface of the glass sleeve.

10. The method for preparing the all-glass single-mode polarization-maintaining optical fiber collimator according to claim 6, characterized in that: Step S5 includes the following steps: S51: adjusting the position of the structure formed in step S4 so that the collimated light beam emitted by the structure formed in step S4 is directly input into the detector; S52: adjusting the position of the optical fiber end face of the optical fiber core, and using a detector to obtain the collimated beam waist radius, collimated beam waist position, collimated light spot diameter and collimated divergence angle of the collimated light beam output when the optical fiber end face position is different; S53: using a detector to measure the polarization state of the collimated light beam output by the current structure, and rotating and adjusting the current structure according to the current polarization state of the collimated light beam; S54: Repeat steps S52 to S53 until the collimated beam waist radius, collimated beam waist position, collimated light spot diameter, collimated divergence angle and collimated beam polarization state of the collimated beam currently output meet the design requirements.

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