Air hole-groove auxiliary intermediate infrared optical fiber

Abstract

The utility model discloses an air hole-groove auxiliary mid-infrared optical fiber, which comprises a fiber core formed by a plurality of first tellurate glass rods, one of the first tellurate glass rods is positioned at the geometric center of the mid-infrared optical fiber, and the rest of the first tellurate glass rods are positioned at the geometric center of the mid-infrared optical fiber as a reference. The upper, lower, left and right sides are symmetrically distributed; the plurality of air holes are distributed on the two sides of the fiber core in a non-circular symmetrical manner; the groove surrounds the outer sides of the fiber core and the air hole and is formed by a second tellurate glass rod; and the cladding layer is formed by the third tellurate glass rod, and the refractive index of the cladding layer is higher than that of the groove and lower than that of the fiber core. The non-circular symmetrical air holes are formed in the fiber core, the circular symmetry of a mode is destroyed, the purpose of leaking a high-order mode is achieved, and dual-mode large-mode-area transmission of the optical fiber is achieved. The optical fiber is assisted by the groove, and the groove with low refractive index is used, so that the bending loss of the optical fiber is reduced.

Description

Technical Field

[0001] This application relates to the field of optical fiber technology, and particularly to an air-hole-groove assisted mid-infrared optical fiber. Background Art

[0002] Optical fibers have the characteristics of light weight, flexibility and easy bending. Compared with space optical systems, optical systems based on mid-infrared optical fibers can, on the one hand, maintain the beam output quality, greatly reduce the volume of the system, and improve the compactness. On the other hand, they can also realize the separate installation of the laser source or detector and the transmitting or receiving system, greatly improving the degrees of freedom in system design, installation and maintenance. At the same time, by using the optical fiber beam combining technology, the beam combining of multiple optical fibers can be easily realized, so as to obtain a high-energy mid-infrared laser output. Therefore, mid-infrared optical fibers have important research significance.

[0003] Optical fibers with a large mode field area are the most direct and effective way to improve the power of fiber lasers, and at the same time, they can also eliminate the adverse effects brought by nonlinear effects. However, in order to ensure the beam quality, when the laser is transmitted, how to reduce the bending loss while ensuring a large mode field area of the optical fiber is a research difficulty.

[0004] At present, the realization of large mode field optical fibers mainly depends on three paths: optical fiber structure design, mode selection control and mode conversion. Among them, leaky channel optical fibers achieve the purpose of leaking high-order modes by introducing asymmetric air holes and have good performance. Although low-bending-loss dual-mode photonic crystal optical fibers are disclosed in the prior art, realizing the dual-mode operation of the fundamental mode and the second-order mode Although researchers have provided us with different solutions, how to reduce the bending loss of the optical fiber while ensuring a large mode field area and realize high-power laser transmission is still a research difficulty at present.

[0005] In view of the above problems, there is an urgent need for a new type of mid-infrared optical fiber to solve the above technical problems. Utility Model Content

[0006] In view of this, this application provides an air-hole-groove assisted mid-infrared optical fiber. The main purpose is to solve the problem of reducing the bending loss of the optical fiber while ensuring a large mode field area, and to solve the technical problem that traditional optical fibers cannot realize high-power laser transmission.

[0007] According to the first aspect of this application, an air-hole-groove assisted mid-infrared optical fiber is provided, including: a core,

[0008] It is composed of multiple first tellurite glass rods, one of the first tellurite glass rods is located at the geometric center of the mid-infrared fiber, and the remaining first tellurite glass rods are symmetrically distributed in the four directions of up, down, left, and right with the geometric center of the mid-infrared fiber as the reference;

[0009] Multiple air holes arranged in non-circular symmetry are distributed on both sides of the core;

[0010] A groove, which is arranged to surround the outside of the core and the air holes, is composed of a second tellurite glass rod;

[0011] A cladding, which is composed of a third tellurite glass rod, and the refractive index of the cladding is higher than that of the groove and lower than that of the core.

[0012] Further, the diameter of the third tellurite glass rod is larger than the diameter of the first tellurite glass rod.

[0013] Further, the refractive index of the third tellurite glass rod is 2.05;

[0014] The refractive index difference between the first tellurite glass rod and the third tellurite glass rod is , and the range is 0.0029 - 0.005;

[0015] The refractive index difference between the second tellurite glass rod and the third tellurite glass rod is , and the range is 0.01 0.08.

[0016] Further, the core, the air holes, the groove and the cladding are respectively axially symmetrically distributed about the geometric center of the fiber in the cross-section of the fiber.

[0017] Further, the groove is an annular structure surrounding the core and the air holes, and the center of the groove coincides with the geometric center of the fiber;

[0018] The cladding uniformly wraps the groove with the geometric center of the fiber as the reference.

[0019] Further, the radius of the fiber is 62.5 , and the working wavelength has a value range of 2 -5 ;

[0020] The spacing between adjacent cores has a value range of 12 -14.5 The value range of is 3 - 4

[0021] The bending radius of the optical fiber has a value range of 0.1 - 0.8 , the cross-sectional radius of the groove is 6 , the radius of the air hole is 5 .

[0022] Furthermore, when the working wavelength of the optical fiber is 2.5 , the fundamental mode has a maximum effective mode field area of 1405.84 , and the second-order degenerate mode has a maximum effective mode field area of 1360.67 ;

[0023] When the working wavelength of the optical fiber is 2.5 , and the bending radius is greater than 0.1 and less than or equal to 0.8 , the bending loss of the optical fiber has a value range of less than 0.005 .

[0024] Furthermore, the effective mode field area ;

[0025] wherein, is the electric field strength of the optical fiber.

[0026] Furthermore, the effective refractive index of the optical fiber ;

[0027] wherein, represents the propagation constant, represents the wave number in vacuum, represents the real part.

[0028] Furthermore, the bending loss of the optical fiber ;

[0029] wherein, represents the imaginary part of the effective refractive index; is the working wavelength.

[0030] An air-hole - trench assisted mid-infrared fiber provided by the present application. In the fiber designed by this patent of the present application, non-circular symmetric air holes are arranged inside the core to break the circular symmetry of the mode, so as to achieve the purpose of leaking high-order modes and realize the dual-mode large-mode area transmission of the fiber. The mid-infrared fiber in the present application adopts trench assistance and uses trenches with low refractive index to reduce the bending loss of the fiber. In addition, the fiber in the present application uses TZLB tellurite glass with different ratios as the materials of the trench, core, and cladding, realizing the high-power transmission of 2 - 5 mid-infrared light. The fiber designed by this patent can be used as the pump source of a high-power mid-infrared fiber laser when implemented in a laser through fiber coupling technology.

[0031] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features, and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings, as part of the present application, are used to provide a further understanding of the present utility model. The schematic embodiments and descriptions thereof of the present application are used to explain the present application, but do not constitute an improper limitation to the present application. Obviously, the drawings in the following description are only some embodiments, and for those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0033] In the drawings:

[0034] Figure 1 shows a schematic structural diagram of the air-hole - trench assisted mid-infrared fiber provided by the embodiment of the present application;

[0035] Figure 2 shows a schematic diagram of the infrared light wavelength of the dual-mode transmission of the air-hole - trench assisted mid-infrared fiber provided by the embodiment of the present application;

[0036] Figure 3 shows a corresponding diagram of the relationship between the core pitch and the effective refractive index of the dual-mode transmission of the air-hole - trench assisted mid-infrared fiber provided by the embodiment of the present utility model;

[0037] Figure 4 shows a corresponding diagram of the relationship between the core pitch and the effective mode field area of the dual-mode transmission of the air-hole - trench assisted mid-infrared fiber provided by the embodiment of the present application;

[0038] Figure 5 shows a corresponding diagram of the relationship between the cross-sectional radius of the trench and the effective refractive index of the dual-mode transmission of the air-hole - trench assisted mid-infrared fiber provided by the embodiment of the present utility model;

[0039] Figure 6 Shows the corresponding diagram of the relationship between the core radius and the effective mode field area of the air hole-groove assisted mid-infrared fiber dual-mode transmission provided by the embodiments of the present application;

[0040] Figure 7 Shows the corresponding diagram of the relationship between the bending radius and the bending loss of the fiber of the air hole-groove assisted mid-infrared fiber dual-mode transmission provided by the embodiments of the present application;

[0041] Figure 8 Shows the corresponding diagram of the relationship between the bending radius and the effective mode field area of the fiber of the air hole-groove assisted mid-infrared fiber dual-mode transmission provided by the embodiments of the present application.

[0042] Reference numerals in the drawings:

[0043] 1. Core; 2. Air hole; 3. Groove; 4. Cladding.

[0044] It should be noted that these drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments in conjunction with the drawings in the embodiments of the present application. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0046] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application 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 should not be construed as a limitation to the present application.

[0047] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" 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 directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0048] Embodiment

[0049] Such as Figure 1-8As shown in the figure, an air-hole and trench-assisted mid-infrared fiber. This air-hole and trench-assisted mid-infrared fiber mainly includes four parts: a core 1, air holes 2, trenches 3, and a cladding 4. Each part is axially symmetric about the geometric center of the fiber in the fiber cross-section. The specific structure is as follows: The core 1 is composed of multiple first tellurite glass rods. One of the first tellurite glass rods is located at the geometric center position of the mid-infrared fiber, and the rest of the first tellurite glass rods are symmetrically distributed in the four directions of up, down, left, and right with the geometric center of the infrared fiber as the reference. This distribution method helps to optimize the optical field distribution of the fiber and improve the transmission efficiency of optical signals in the core. Multiple non-circularly symmetrically arranged air holes 2 are distributed on both sides of the core 1. In this application, the introduction of air holes can change the optical field distribution in the fiber, break the circular symmetry of the mode, achieve the purpose of leaking high-order modes, realize the dual-mode large-mode area transmission of the fiber, enhance the confinement effect on optical signals, and reduce the transmission loss of the fiber. The trench 3 is arranged to surround the outside of the core 1 and the air holes 2 and is composed of second tellurite glass rods. Specifically, the radius of the trench 3 is d3. In this application, the trench 3 is an annular structure surrounding the core 1 and the air holes 2, and its center coincides with the geometric center of the fiber. The existence of the trench 3 further optimizes the refractive index distribution of the fiber, helps to better confine the optical signal in the core region, and reduces the leakage of the optical signal to the cladding 4. The cladding 4 is arranged and composed of third tellurite glass rods. The cladding 4 evenly wraps the trench 3 with the geometric center of the fiber as the reference. The refractive index of the cladding 4 is higher than that of the trench 3 and lower than that of the core 1. In this application, this refractive index gradient distribution enables the optical signal to be efficiently transmitted in the core in a total reflection manner, while effectively suppressing the generation of high-order modes and ensuring the single-mode transmission characteristics of the fiber.

[0050] In this embodiment, the diameter of the third tellurite glass rod is greater than the diameter of the first tellurite glass rod. Specifically, as shown in the appendix Figure 1 In this application, the value range of the radius d1 of the first tellurite glass rod of the core 1 is: 3 - 4 , and the overall radius D of the fiber is 62.5 ; In this application, this diameter difference helps to achieve a reasonable refractive index distribution and optical field confinement inside the fiber.

[0051] In a feasible embodiment, the refractive index of the third tellurite glass rod is 2.05;

[0052] The refractive index difference between the first tellurite glass rod and the third tellurite glass rod is within a first specific range and the range is 0.0029 - 0.005;

[0053] The refractive index difference between the second tellurite glass rod and the third tellurite glass rod is within a second specific range and ranges from 0.01 to 0.08. The design of this refractive index difference is crucial for optimizing the light signal convergence ability of the core; the refractive index difference between the second tellurite glass rod and the third tellurite glass rod ranges from 0.01 to 0.08. A reasonable refractive index difference in this application can ensure that the trench effectively restricts and isolates light signals. The optical fiber in this application uses tellurite glass with different ratios of TZLB ( ) as the materials for the trench, core, and cladding, achieving high-power transmission of mid-infrared light with wavelengths of 2 to 5

[0054] In this embodiment, the core 1, air holes 2, trench 3, and cladding 4 are axially symmetric about the geometric center of the optical fiber in the cross-section of the optical fiber. This symmetric structure in this application has significant advantages. The symmetric structure can ensure that the light signal is uniformly affected when transmitting in the optical fiber, making the light field distribution more stable, and reducing problems such as light signal scattering and mode coupling caused by asymmetric structures. At the same time, the symmetric structure facilitates the design, preparation, and performance analysis of the optical fiber, is conducive to achieving precise control of the optical fiber performance, and improving the consistency and repeatability of the optical fiber.

[0055] In a feasible embodiment, the trench 3 is an annular structure that surrounds and encloses the core 1 and air holes 2, and the center of the trench 3 coincides with the geometric center of the optical fiber; this annular structure in this application can uniformly restrict the light signal, making the light signal more concentrated in the core area and reducing the diffusion of the light signal to the surrounding area. At the same time, the coincidence of the center of the circle with the geometric center of the optical fiber ensures the symmetry and stability of the light signal transmission, which is conducive to achieving low-loss and high-quality light signal transmission. In addition, the cladding 4 uniformly wraps the trench 3 based on the geometric center of the optical fiber. The uniformly wrapped structure can provide a stable external environment for the entire internal structure of the mid-infrared optical fiber, effectively blocking the influence of external factors (such as humidity, temperature changes, etc.) on the internal light transmission of the optical fiber, and ensuring the stability and reliability of the optical fiber performance.

[0056] In a feasible embodiment, the radius of the optical fiber is 62.5 , and the working wavelength ranges from 2 to 5 ;

[0057] The spacing between adjacent cores ranges from 12 to 14.5 , and the radius of the core 1 The value range is 3 -4 ;

[0058] The bending radius of the optical fiber has a value range of 0.1 -0.8 , and the cross-sectional radius of the groove 3 is 6 , and the radius of the air hole 2 is 5 .

[0059] In this embodiment, when the working wavelength of the optical fiber is 2.5 , the maximum effective mode field area of the fundamental mode is 1405.84 , and the maximum effective mode field area of the second-order degenerate mode is 1360.67 ; is 1360.67 ;

[0060] When the working wavelength of the optical fiber is 2.5 , and the bending radius is greater than 0.1 and less than or equal to 0.8 , the bending loss of the optical fiber has a value range of less than 0.005 .

[0061] In this embodiment, the effective mode field area ;

[0062] wherein, is the electric field strength of the optical fiber.

[0063] In this embodiment, the effective refractive index of the optical fiber ;

[0064] wherein, represents the propagation constant, represents the wave number in vacuum, represents the real part.

[0065] In this embodiment, the bending loss of the optical fiber ;

[0066] wherein, represents the imaginary part of the effective refractive index; is the working wavelength.

[0067] In a feasible implementation, as shown in the attached Figure 1 figures, as a preferred implementation of the present application, an air hole-groove assisted mid-infrared optical fiber includes a core 1, large air holes 2, grooves 3, and a cladding 4. The overall radius of the optical fiber is 62.5 , the core radius is 3 , the groove width is 6 , the air hole radius is 5 , the core pitch is 14 , the cladding refractive index is 2.05, and the difference between the core refractive index and the cladding refractive index is , the difference between the cladding refractive index and the groove refractive index is 0.01, and the working wavelength is 2.6 . Figure 1 shows the refractive index distribution of the optical fiber shown in this embodiment in the transverse direction. The maximum effective mode field area of the optical fiber mode of this embodiment is 1441.49 , and the maximum effective mode field area of the mode is 1395.65 . When the bending radius is greater than 0.1 , the maximum bending loss of the optical fiber is 0.004 , realizing the transmission of two modes.

[0068] The optical fiber of this embodiment can transmit mid-infrared light with a wavelength of 2.6 , which has important applications in fields such as lasers.

[0069] The above are only the preferred embodiments in the present application, and do not impose any formal restrictions on the present application. Although the present application has been disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art of this patent, without departing from the scope of the technical solution of the present application, can make some changes or modifications using the technical content prompted above into equivalent embodiments of equivalent changes. The implementation schemes in the above embodiments can also be further combined or replaced. However, as long as the content does not depart from the technical solution of the present application, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present application still fall within the scope of the present application.

Claims

1. An air-hole and groove assisted mid-infrared optical fiber, characterized in that, Comprising: A core (1), which is composed of a plurality of first tellurite glass rods, wherein one of the first tellurite glass rods is located at the geometric center of the mid-infrared fiber, and the remaining first tellurite glass rods are symmetrically distributed in the up, down, left, and right directions with the geometric center of the mid-infrared fiber as the reference; A plurality of non-circularly symmetrically arranged air holes (2), which are distributed on both sides of the core (1); A groove (3), which is disposed around and surrounds the outside of the core (1) and the air holes (2), and is composed of a second tellurite glass rod; A cladding (4), which is disposed and composed of a third tellurite glass rod, and the refractive index of the cladding (4) is higher than that of the groove (3) and lower than that of the core (1).

2. The mid-infrared fiber according to claim 1, wherein the diameter of the third tellurite glass rod is larger than the diameter of the first tellurite glass rod.

3. The mid-infrared fiber according to claim 2, wherein the refractive index of the third tellurite glass rod is 2.05; The refractive index difference between the first tellurite glass rod and the third tellurite glass rod is , in the range of 0.0029 - 0.005; The refractive index difference between the second tellurite glass rod and the third tellurite glass rod is , in the range of 0.01 0.

08.

4. The mid-infrared fiber according to claim 2, wherein the core (1), the air holes (2), the groove (3), and the cladding (4) are respectively axially symmetrically distributed about the geometric center of the fiber in the cross-section of the fiber.

5. The mid-infrared fiber according to claim 4, wherein the groove (3) is an annular structure that surrounds and surrounds the core (1) and the air holes (2), and the center of the groove (3) coincides with the geometric center of the fiber; the cladding (4) uniformly wraps the groove (3) with the geometric center of the fiber as the reference.

6. The mid-infrared fiber according to claim 5, wherein The radius of the optical fiber is 62.5 , and the operating wavelength ranges from 2 to 5 ; The spacing adjacent to the core has a value range of 12 -14.5 , and the radius of the core (1) has a value range of 3 -4 ; The bending radius of the optical fiber ranges from 0.1 to 0.8 ; the cross-sectional radius of the groove (3) is 6 ; the radius of the air hole (2) is 5 .

7. The mid-infrared fiber according to claim 6, wherein The optical fiber at the operating wavelength is 2.5 When the maximum effective mode field area of the fundamental mode is 1405.84 and the maximum effective mode field area of the second-order degenerate mode is 1360.67 ; ​ The optical fiber has a working wavelength of 2.5 , and the bending radius is greater than 0.1 and less than or equal to 0.8 . When this is the case, the bending loss of the optical fiber is in the range of less than 0.005 .

8. The mid-infrared fiber according to claim 6, wherein Effective mode field area ; Among them, is the electric field strength of the optical fiber.

9. The mid-infrared fiber according to claim 6, wherein Effective refractive index of optical fiber ; Among them, represents the propagation constant, represents the wave number in vacuum, represents the real part.

10. The mid-infrared fiber according to claim 6, wherein Bending Loss of Optical Fiber ; wherein, represents the imaginary part of the effective refractive index; is the operating wavelength.

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