Middle and far infrared heterogeneous integrated optical fiber beam combiner and preparation method thereof

Abstract

The invention discloses a mid-infrared and far-infrared heterogeneous integrated optical fiber combiner and a preparation method thereof, and belongs to the technical field of mid-infrared optical fiber devices.The combiner comprises six sulfur-based chalcogenide optical fibers with the working wave band being 3-5 microns and four Te-based chalcogenide optical fibers with the working wave band being 7-11 microns, the six sulfur-based chalcogenide optical fibers and the four Te-based chalcogenide optical fibers are mixed in a heterogeneous mode, and ten input optical fibers are closely arranged according to a regular triangle; beam combination transmission is formed by optimizing a low-temperature fused biconical taper process, the optical fiber is precisely welded with an output optical fiber with a slightly large core diameter, and finally the optical fiber is packaged. The beam combiner realizes broadband efficient laser transmission, has the characteristics of excellent beam quality, high synthesis efficiency, large total output power, compact structure and strong stability, and can be widely applied to the fields of optical fiber sensing, laser processing, national defense and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of mid-infrared optical fiber devices, and in particular relates to a mid- and far-infrared heterogeneous integrated optical fiber combiner and a preparation method thereof. Background Art

[0002] With the rapid development of mid- and far-infrared laser technology, the demand for high-power, high-quality, multi-wavelength lasers is increasing in many high-tech fields such as infrared detection, fiber optic sensing, material processing, and laser communications. In these fields, whether it is the pursuit of more accurate infrared detection capabilities or the improvement of the sensitivity and range of fiber optic sensing, it is inseparable from the support of advanced laser technology. As an important fiber optic device, the fiber combiner can realize the efficient synthesis and transmission of multi-path laser beams. However, the current fiber combiners based on homogeneous mid-infrared optical fibers have the following problems: Working band limitations: Homogeneous fiber combiners are difficult to cover multiple mid- and far-infrared bands (such as 3~5μm and 7~11μm) at the same time, which limits their application in multi-wavelength laser systems.

[0003] The contradiction between output beam quality and transmission efficiency: During the optical fiber tapering process, too large or too small tapering ratio will lead to a decrease in beam quality or energy transmission loss.

[0004] Integration and power output limitations: Traditional fiber combiner design is difficult to balance high integration and wide-band output performance, affecting the overall application effect of the device. Summary of the invention

[0005] The present invention provides a mid-to-far infrared heterogeneous integrated optical fiber combiner and a preparation method thereof, which realizes efficient beam combining of multi-wavelength lasers by optimizing the design of heterogeneous chalcogenide optical fiber combination, taper parameters and optical fiber fusion structure.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: In a first aspect, the present invention provides a mid- and far-infrared heterogeneous integrated fiber combiner, comprising a fiber bundle and an output fiber fused together, wherein the fiber bundle comprises a plurality of sulfur-based chalcogenide fibers whose working band covers 3 to 5 μm and a plurality of Te-based chalcogenide fibers whose working band covers 7 to 11 μm, the sulfur-based chalcogenide fibers and the Te-based chalcogenide fibers in the fiber bundle are arranged in an equilateral triangle structure, and the core diameter of the output fiber is larger than the effective diameter of the fiber bundle after tapering.

[0007] A further improvement of the present invention is that the sulfur-based chalcogenide optical fiber and the Te-based chalcogenide optical fiber are both input optical fibers, and the fusion length of the optical fiber bundle and the output optical fiber and the length of the input optical fiber before the tapered zone are both less than 50 cm.

[0008] A further improvement of the present invention is that the optical fiber bundle comprises six sulfur-based chalcogenide optical fibers with a working band covering 3 to 5 μm and four Te-based chalcogenide optical fibers with a working band covering 7 to 11 μm.

[0009] A further improvement of the present invention is that the sulfur-based chalcogenide optical fibers and Te-based chalcogenide optical fibers in the optical fiber bundle are arranged in layers, and each layer includes the sulfur-based chalcogenide optical fibers and Te-based chalcogenide optical fibers in the optical fiber bundle.

[0010] A further improvement of the present invention is that a sleeve is provided outside the optical fiber bundle.

[0011] In a second aspect, the present invention provides a method for preparing a mid- and far-infrared heterogeneous integrated fiber combiner, comprising the following steps: Step 1, arranging N input optical fibers in an equilateral triangle structure to form an optical fiber bundle, N≥3; the input optical fibers include sulfur-based chalcogenide optical fibers and Te-based chalcogenide optical fibers; Step 2, putting a sleeve outside the optical fiber bundle to obtain an assembly, using a fusion taper process to taper the assembly, and taper the input optical fiber into an N-core optical fiber; Step 3, fusing the tapered optical fiber bundle with the output optical fiber; Step 4: solidify and package the tapered area, the fusion area and the waist area, wherein the waist area is the area between the tapered area and the fusion area.

[0012] A further improvement of the present invention is that in step 2, during the taper process, the taper ratio is optimized according to experimental results.

[0013] A further improvement of the present invention is that in step 2, the length of the tapered area is ≤50 cm.

[0014] A further improvement of the present invention is that in step 3, the welded area is polished after welding.

[0015] A further improvement of the present invention is that in step 4, metal or special polymer is used to solidify and encapsulate the tapered area, the fusion area and the waist area.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: The mid- and far-infrared heterogeneous integrated fiber combiner provided by the present invention has the following advantages: 1) Wide-band efficient transmission: By mixing heterogeneous optical fibers with working bands covering 3~5μm and 7~11μm, and arranging them closely in an equilateral triangle, efficient coverage of the 3~5μm and 7~11μm bands is achieved, the working band range of the combiner is expanded, and the requirements for multi-wavelength efficient transmission are met.

[0017] 2) High output power: All input optical fibers are closely arranged in an equilateral triangle structure to ensure the uniformity of optical fiber beam combination and improve the synthesis efficiency and beam quality. After testing, the synthesis efficiency of the combiner is ≥95%, the single-channel optical fiber input power is 1 W, and the total combined output power is ≥8 W.

[0018] The method for preparing the mid- and far-infrared heterogeneous integrated optical fiber combiner provided by the present invention has the following advantages: 1) On the basis of controlling the temperature and taper ratio, reduce the core size to achieve single-mode transmission while avoiding energy crosstalk caused by too small core diameter 2) The tapered ten-core fiber is fused with the output fiber with a slightly larger core diameter to optimize the beam coupling efficiency; 3) High-temperature resistant and high-strength packaging materials are used for packaging to ensure the long-term stability of the device in complex environments, so that the prepared mid- and far-infrared heterogeneous integrated fiber combiner has the characteristics of high stability and reliability, ensuring its long-term operating performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : Schematic diagram of the optical fiber bundle structure arranged in a regular triangle; Figure 2 : Schematic diagram of the fusion taper and fusion splicing process of the optical fiber combiner; Figure 3 : The appearance of the packaged high-performance mid- and far-infrared heterogeneous integrated fiber combiner (placed on the fiber platform); Figure 4 : 10×1 combiner output fiber light field distribution diagram.

[0020] In the attached figure: 1. input optical fiber; 2. output optical fiber; 3. taper area; 4. waist area; 5. fusion point; 6. sleeve; 7. packaging shell; 8. jumper head; 9. light source; 11. S-based chalcogenide optical fiber; 12. Te-based chalcogenide optical fiber. DETAILED DESCRIPTION

[0021] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. used herein indicate orientations or positional relationships based on the orientations 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.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] The present invention relates to a heterogeneous optical fiber mixing technology and a high-efficiency fused tapered technology, specifically to a high-performance heterogeneous integrated optical fiber combiner suitable for high-quality laser transmission in mid- and far-infrared bands and a preparation method thereof.

[0026] A mid- and far-infrared heterogeneous integrated fiber combiner comprises a plurality of sulfur-based chalcogenide fibers 11 with a working band covering 3 to 5 μm and a plurality of Te-based chalcogenide fibers 12 with a working band covering 7 to 11 μm. The sulfur-based chalcogenide fibers 11 and the Te-based chalcogenide fibers 12 are closely layered and arranged in a regular triangle structure, an external sleeve 6 is provided, and the fibers are fused with a section of output fiber 2 after fusion taper; the core diameter of the output fiber 2 is larger than the effective diameter of the fiber bundle after taper.

[0027] The sulfur-based chalcogenide optical fibers 11 and the Te-based chalcogenide optical fibers 12 are arranged in layers, and each layer includes the sulfur-based chalcogenide optical fibers 11 and the Te-based chalcogenide optical fibers 12 in the optical fiber bundle.

[0028] Preferably, the packaging shell is made of metal or special polymer.

[0029] Preferably, the package shell is made of copper (Cu), aluminum (Al), aluminum alloy or Kovar. Copper has good thermal conductivity, which helps to ensure that the combiner can still work stably in high temperature environment. Aluminum also has good thermal conductivity and has a smaller density. In the package of the combiner, the aluminum shell can effectively dissipate heat while reducing the overall weight. Kovar has the characteristics of low expansion and corrosion resistance, and is suitable for package shells that require high-precision sealing and good thermal matching.

[0030] A method for preparing a mid- and far-infrared heterogeneous integrated optical fiber combiner comprises the following steps: Step 1, arranging N input optical fibers 1 in an equilateral triangle structure to form an optical fiber bundle, where N is greater than or equal to 3; the input optical fiber 1 includes a sulfur-based chalcogenide optical fiber 11 with a working band covering 3 to 5 μm and a plurality of Te-based chalcogenide optical fibers 12 with a working band covering 7 to 11 μm; Step 2, sleeve the sleeve 6 outside the optical fiber bundle to obtain an assembly, and use the fusion taper process to taper the assembly, and taper the input optical fiber 1 into an N-core optical fiber; During the taper process, the taper ratio is optimized based on experimental results. The taper ratio is the ratio of the input fiber diameter after taper to the original input fiber diameter. If the taper ratio is too large, the core diameter may be reduced too much, which may cause crosstalk in the fiber and affect the beam quality; if the taper ratio is too small, the mode field size cannot be fully compressed, resulting in an increase in the divergence angle of the output beam.

[0031] Step 3, fusing the tapered optical fiber bundle with the output optical fiber 2; Step 4: Use the packaging shell 7 to solidify and package the tapered area 3, the fusion area 5 and the waist area 4.

[0032] Example 1 Reference Figure 1 This embodiment provides an optical fiber bundle, and selects 6 sulfur-based chalcogenide glass optical fibers 11 with a working band covering 3-5 μm and 4 Te-based chalcogenide glass optical fibers 12 with a working band covering 7-11 μm as input optical fibers. The sulfur-based chalcogenide glass optical fibers and the Te-based chalcogenide glass optical fibers have good optical complementarity and can cover the efficient transmission requirements of the target band.

[0033] The arrangement is: 6 sulfur-based chalcogenide glass fibers and 4 Te-based chalcogenide glass fibers are closely arranged in a regular triangle structure. This arrangement can effectively utilize space, ensure uniform energy distribution between fibers, and avoid fiber damage caused by local overheating or excessive power.

[0034] Six sulfur-based chalcogenide glass fibers and four Te-based chalcogenide glass fibers are arranged into four layers, with the bottom layer being the first layer. The first layer is arranged from left to right in sequence: two sulfur-based chalcogenide glass fibers 11, one Te-based chalcogenide glass fiber 12, and one sulfur-based chalcogenide glass fiber 11; the second layer is arranged from left to right in sequence: two Te-based chalcogenide glass fibers 12 and one sulfur-based chalcogenide glass fiber 11; the third layer is arranged from left to right in sequence: one sulfur-based chalcogenide glass fiber 11 and one Te-based chalcogenide glass fiber 12; and the fourth layer has only one sulfur-based chalcogenide glass fiber 11.

[0035] The optical fiber combination arranged in an equilateral triangle is all multi-mode optical fiber before tapering. The design goal is to reduce the optical fiber core diameter to an appropriate size for single-mode transmission through the tapering process, while taking into account the input energy coupling efficiency and beam quality.

[0036] Example 2 The present embodiment provides an optical fiber bundle, including three sulfur-based chalcogenide glass optical fibers and three Te-based chalcogenide glass optical fibers, which are arranged in three layers. The bottom layer is the first layer. The first layer is arranged from left to right in sequence: two Te-based chalcogenide glass optical fibers 12 and one sulfur-based chalcogenide glass optical fiber 11; the second layer is arranged from left to right in sequence: one sulfur-based chalcogenide glass optical fiber 11 and one Te-based chalcogenide glass optical fiber 12; the third layer has only one sulfur-based chalcogenide glass optical fiber 11.

[0037] Example 3 This embodiment provides a mid- and far-infrared heterogeneous integrated fiber combiner, comprising 10 input optical fibers 1 with working bands covering 3-5 μm and 7-11 μm, of which 6 are sulfur-based chalcogenide optical fibers and 4 are Te-based chalcogenide optical fibers. The 10 input optical fibers are closely arranged in a regular triangle structure, and after being sleeved with a sleeve 6, they are fused and tapered and then fused with a section of output optical fiber 2, and the core diameter of the output optical fiber is larger than the effective diameter of the 10-core optical fiber after taper.

[0038] After the taper fusion splicing, a taper region 3, a waist region 4 and a fusion splicing region 5 are formed between the input optical fiber 1 and the output optical fiber. The taper region 3, the waist region 4 and the fusion splicing region 5 are encapsulated by an encapsulation shell 7.

[0039] Reference Figure 3 The end of the input optical fiber 1 that is not fused with the output optical fiber, every two input optical fibers are connected to a light source, and a jumper head 8 is installed at the end of the output optical fiber 2 away from the input optical fiber 1.

[0040] Example 4 This embodiment provides a mid- and far-infrared heterogeneous integrated fiber combiner, comprising 6 input optical fibers 1 with working bands covering 3-5 μm and 7-11 μm, of which 3 are sulfur-based chalcogenide optical fibers and 2 are Te-based chalcogenide optical fibers. The 6 input optical fibers are closely arranged in a regular triangle structure and are fused with a section of output optical fiber 2 after fusion taper. The core diameter of the output optical fiber is larger than the effective diameter of the 10-core optical fiber after taper.

[0041] There are a tapered region 3, a waist region 4 and a fusion region 5 between the input optical fiber 1 and the output optical fiber 2. The tapered region 3, the waist region 4 and the fusion region 5 are encapsulated by an encapsulating shell 7.

[0042] The input optical fiber 1 is at one end away from the output optical fiber 2 , and every two input optical fibers 1 are connected to a light source; and a jumper head 8 is installed at one end of the output optical fiber 2 away from the input optical fiber 1 .

[0043] Example 5 Reference Figure 2 This embodiment provides a method for preparing a mid- and far-infrared heterogeneous integrated fiber combiner, comprising the following steps: Step 1, arranging 10 input optical fibers 1 in a regular triangle structure to form an optical fiber bundle; the 10 input optical fibers include 6 sulfur-based chalcogenide glass optical fibers 11 with a working band covering 3-5 μm and 4 Te-based chalcogenide glass optical fibers 12 covering 7-11 μm; Step 2, sleeve the sleeve 6 outside the optical fiber bundle to obtain an assembly, and use the melt taper process to taper the assembly to optimize the optical fiber core diameter, and taper the 10 input optical fibers 1 into a 10-core optical fiber; the sleeve 6 is a low refractive index sleeve.

[0044] Taper ratio control in this step: During the tapering process, the tapering ratio is optimized according to the experimental results, and the taper temperature and taper speed are controlled to ensure that the core diameter of the optical fiber after tapering can meet the requirements of single-mode transmission.

[0045] Fiber length in the tapered area: The length of the tapered area 3 is designed to be ≤50 cm. By precisely controlling the length of the tapered area, significant excitation of high-order modes is avoided, thereby maximizing the beam quality and transmission efficiency.

[0046] Step 3, fusing the tapered optical fiber bundle with the output optical fiber 2; Selection of output optical fiber 2: A section of sulfur-based chalcogenide glass optical fiber is selected as output optical fiber 2, and its core diameter is slightly larger than the effective diameter of the 10-core optical fiber after tapering.

[0047] Fusion process: Use a fusion splicer to precisely fusion-splice the output fiber 2 with the tapered 10-core fiber bundle to ensure that the beam energy is coupled from the 10-core fiber to the output fiber with high efficiency. The fusion power is controlled at 9W and the time is 2s.

[0048] The welding process of welding area 5 is to reduce the reflection and scattering loss at the connection, while improving the stability of the output power. The welding area 5 is polished to reduce the insertion loss and thermal effect.

[0049] Step 4: solidify and package the entire combiner.

[0050] Selection of packaging materials: Use high temperature resistant and high strength materials (such as metal or special polymer) to prepare the packaging shell 7 to ensure the long-term stability of the device under high power working conditions. The packaging shell is used to encapsulate the taper area 3, waist area 4 and fusion point, and a jumper head 8 is installed at the other end of the output optical fiber 2 to obtain a mid- and far-infrared heterogeneous integrated optical fiber combiner.

[0051] The performance test of the mid- and far-infrared heterogeneous integrated fiber combiner prepared in Example 3 includes: performing comprehensive simulation test calculations on the light field distribution within the working spectrum range (3-5 μm and 7-11 μm) of the combiner, and the obtained 10×1 combiner output fiber light field distribution diagram is shown in the figure below: Figure 4 As shown, verify that it meets the design requirements.

[0052] Description of the optical field distribution diagram: The taper ratio of the fiber combiner is set to 2.5. The core diameter and cladding diameter of the 10 input optical fibers before taper are 105μm and 125μm respectively. The total core diameter of the 10-core optical fibers after taper is approximately 179.9038μm in the Y direction and 150μm in the X direction. The core diameter of the spliced ​​output optical fiber is determined to be approximately 200μm (slightly larger than the core diameter of the 7-core optical fiber), and the cladding diameter is approximately 600μm, which is the same as the cladding diameter of the optical fiber after taper. Theoretical simulation results show that under this combiner structure, the output beam quality (BBP value) is approximately: 50mm.mrad in the X direction and 45.6mm.mrad in the Y direction, which meets the design requirements.

[0053] The beam combiner realizes wide-band and efficient laser transmission, and has the characteristics of excellent beam quality, high synthesis efficiency, large total output power, compact structure and strong stability. It can be widely used in fiber optic sensing, laser processing, national defense and other fields.

[0054] The term "consisting of" describing a combination shall include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, parts or steps herein also contemplates embodiments that consist essentially of these elements, ingredients, parts or steps. By using the term "may", it is intended to illustrate that any of the attributes described that "may" be included are optional.

[0055] Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "an" used to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0056] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the foregoing claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A mid- and far-infrared heterogeneous integrated fiber combiner, characterized in that: The invention comprises a fiber bundle and an output fiber (2) fused together, wherein the fiber bundle comprises a plurality of sulfur-based chalcogenide fibers (11) with a working band covering 3 to 5 μm and a plurality of Te-based chalcogenide fibers (12) with a working band covering 7 to 11 μm, the sulfur-based chalcogenide fibers (11) and the Te-based chalcogenide fibers (12) in the fiber bundle are arranged in an equilateral triangle structure, and the core diameter of the output fiber (2) is larger than the effective diameter of the fiber bundle after tapering.

2. The mid- and far-infrared heterogeneous integrated fiber combiner according to claim 1, characterized in that: The sulfur-based chalcogenide optical fiber (11) and the Te-based chalcogenide optical fiber (12) are both input optical fibers (1), and the fusion length of the optical fiber bundle and the output optical fiber and the length of the input optical fiber (1) before the tapered region (3) are both less than 50 cm.

3. The mid- and far-infrared heterogeneous integrated fiber combiner according to claim 1, characterized in that: The optical fiber bundle comprises six sulfur-based chalcogenide optical fibers (11) with a working wavelength range covering 3 to 5 μm and four Te-based chalcogenide optical fibers (12) with a working wavelength range covering 7 to 11 μm.

4. The mid- and far-infrared heterogeneous integrated fiber combiner according to claim 1, characterized in that: The sulfur-based chalcogenide optical fibers (11) and the Te-based chalcogenide optical fibers (12) in the optical fiber bundle are arranged in layers, and each layer includes the sulfur-based chalcogenide optical fibers (11) and the Te-based chalcogenide optical fibers (12) in the optical fiber bundle.

5. A mid- and far-infrared heterogeneous integrated fiber combiner according to claim 1 or 4, characterized in that: A sleeve (6) is arranged outside the optical fiber bundle.

6. A method for preparing a mid- and far-infrared heterogeneous integrated fiber combiner, characterized in that: The following steps are involved: Step 1, arranging N input optical fibers (1) in an equilateral triangle structure to form an optical fiber bundle, where N is greater than or equal to 3; the input optical fiber (1) comprises a sulfur-based chalcogenide optical fiber (11) and a Te-based chalcogenide optical fiber (12); Step 2, putting a sleeve (6) outside the optical fiber bundle to obtain an assembly, taper the assembly using a fusion taper process, and taper the input optical fiber (1) into an N-core optical fiber; Step 3, fusing the tapered optical fiber bundle with the output optical fiber (2); Step 4: solidify and package the tapered area (3), the fusion area (5) and the waist area (4), wherein the waist area (4) is the area between the tapered area (3) and the fusion area (5).

7. The method for preparing a mid- and far-infrared heterogeneous integrated fiber combiner according to claim 6, characterized in that: In step 2, during the taper process, the taper ratio is optimized according to experimental results.

8. The method for preparing a mid- and far-infrared heterogeneous integrated fiber combiner according to claim 6, characterized in that: In the step 2, the length of the tapered area (3) is ≤50 cm.

9. The method for preparing a mid- and far-infrared heterogeneous integrated fiber combiner according to claim 6, characterized in that: In the step 3, the welded area (5) is polished after welding.

10. The method for preparing a mid- and far-infrared heterogeneous integrated fiber combiner according to claim 6, characterized in that: In the step 4, metal or special polymer is used to solidify and encapsulate the tapered area (3), the fusion area (5) and the waist area (4).

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