Hollow-core optical fiber and solid-core optical fiber connection method and structure

Abstract

The invention discloses a hollow-core optical fiber and solid-core optical fiber connection method and structure, and belongs to the field of optical fibers, and the method comprises the steps: obtaining the mode field diameter, numerical aperture and fiber core refractive index data of a to-be-connected solid-core optical fiber and hollow-core optical fiber through determining a working wavelength; selecting the type of a lens for connection; calculating parameters of the first lens according to the working wavelength, the mode field diameter of the solid core optical fiber, the numerical aperture and the fiber core refractive index data; calculating parameters of the second lens according to the working wavelength, the mode field diameter of the hollow-core optical fiber, the numerical aperture and the fiber core refractive index data; manufacturing the first lens and the second lens according to the parameters of the first lens and the parameters of the second lens; the end portion of the solid core optical fiber is connected with the first lens, the end portion of the hollow core optical fiber is connected with the second lens, the first lens and the second lens are coupled to enable the solid core optical fiber and the hollow core optical fiber to be connected, through the steps, the solid core optical fiber and the hollow core optical fiber are coupled through the two lenses, welding is not needed, and optical signal loss caused by connection is reduced.

Description

Technical Field

[0001] The present invention relates to the field of optical fibers, and in particular to a method and structure for connecting a hollow core optical fiber and a solid core optical fiber. Background Art

[0002] Hollow core fiber (HCF) is a new type of optical waveguide developed based on photonic crystal technology. It is composed of a single medium (usually molten silica or polymer), and the cladding is composed of some air holes that are periodically arranged in the cross section and remain unchanged in the longitudinal direction. It is also called photonic crystal fiber or holey fiber. According to the different light-guiding mechanisms, it can be divided into: refractive index light-guiding type and bandgap light-guiding type. The propagation mechanism of refractive index light-guiding type fiber is similar to that of traditional optical fiber. It is achieved by total reflection when the core refractive index is greater than the effective refractive index of the cladding, while the latter uses the photonic bandgap effect to constrain light to propagate in the core, which changes the transmission medium of light in the optical fiber and fundamentally avoids the problems caused by the intrinsic limitation of the material. Compared with traditional solid core optical fiber, it has the advantages of low delay, low dispersion, low nonlinearity, high laser damage threshold, low thermal sensitivity, radiation resistance, and ultra-wide transmission bandwidth. It is used in optical communication and high-power laser transmission.

[0003] The following methods are used to connect hollow-core optical fibers and solid-core optical fibers: (1) direct fusion splicing using fusion splicing equipment; (2) connecting hollow-core optical fibers and solid-core optical fibers through a fusion taper process; (3) filling or collapsing the hollow-core optical fiber cavity and then connecting through fusion splicing or fusion taper; (4) introducing a transition optical fiber to fusion taper the hollow-core optical fiber, etc. However, these methods will cause loss of optical signals. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a method for connecting a hollow-core optical fiber and a solid-core optical fiber with low optical signal loss.

[0005] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a hollow-core optical fiber and a solid-core optical fiber connection structure with low optical signal loss.

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] A method for connecting a hollow core optical fiber to a solid core optical fiber comprises the following steps:

[0008] Determine the working wavelength, and obtain the mode field diameter, numerical aperture, and core refractive index data of the solid core fiber and hollow core fiber to be connected;

[0009] Select the type of lens to be used for connection;

[0010] Calculate the parameters of the first lens according to the working wavelength, the mode field diameter, numerical aperture, and core refractive index data of the solid core optical fiber; calculate the parameters of the second lens according to the working wavelength, the mode field diameter, numerical aperture, and core refractive index data of the hollow core optical fiber;

[0011] manufacturing the first lens and the second lens according to the parameters of the first lens and the parameters of the second lens;

[0012] The end of the solid core optical fiber is connected to the first lens, and the end of the hollow core optical fiber is connected to the second lens. The first lens and the second lens are coupled to connect the solid core optical fiber and the hollow core optical fiber.

[0013] Furthermore, the lens is any one of a self-focusing lens, a collimating lens, a fiber lens, and a metasurface lens.

[0014] Furthermore, when the lens is a collimating lens, the lens material is N-SF11.

[0015] Furthermore, the beam waist after the solid core optical fiber is connected to the first lens is the same as the beam waist after the hollow core optical fiber is connected to the second lens.

[0016] Furthermore, the method for connecting the hollow-core optical fiber and the solid-core optical fiber also includes a simulation step, and the simulation step is specifically: performing simulation tests on the coupled solid-core optical fiber, the first lens, the second lens and the hollow-core optical fiber to detect the loss caused by the coupling.

[0017] The second object of the present invention is achieved by adopting the following technical solution:

[0018] A hollow-core fiber and solid-core fiber connection structure is manufactured using any of the above-mentioned hollow-core fiber and solid-core fiber connection methods, the hollow-core fiber and solid-core fiber connection structure includes a hollow-core fiber and a solid-core fiber, the hollow-core fiber and solid-core fiber connection structure also includes a first lens and a second lens, the first lens is connected to the end of the solid-core fiber, the second lens is connected to the end of the hollow-core fiber, the beam waist after the solid-core fiber is connected to the first lens is the same as the beam waist after the hollow-core fiber is connected to the second lens, and the first lens is coupled to the second lens.

[0019] Furthermore, the first lens and the second lens are any one of a self-focusing lens, a collimating lens, a fiber lens, and a metasurface lens.

[0020] Furthermore, the first lens and the solid core optical fiber are connected by any one of bonding, snapping and welding.

[0021] Furthermore, the second lens and the hollow-core optical fiber are connected by any one of bonding, snapping, and welding.

[0022] Furthermore, the first lens and the second lens are connected by any one of bonding, snapping, and welding.

[0023] Compared with the prior art, the method for connecting a hollow-core optical fiber and a solid-core optical fiber of the present invention determines the working wavelength, obtains the mode field diameter, numerical aperture, and core refractive index data of the solid-core optical fiber and the hollow-core optical fiber to be connected; selects the type of lens used for connection; calculates the parameters of the first lens according to the working wavelength, the mode field diameter, numerical aperture, and core refractive index data of the solid-core optical fiber; calculates the parameters of the second lens according to the working wavelength, the mode field diameter, numerical aperture, and core refractive index data of the hollow-core optical fiber; manufactures the first lens and the second lens according to the parameters of the first lens and the parameters of the second lens; connects the end of the solid-core optical fiber to the first lens, connects the end of the hollow-core optical fiber to the second lens, and couples the first lens with the second lens to connect the solid-core optical fiber to the hollow-core optical fiber. Through the above steps, the solid-core optical fiber and the hollow-core optical fiber are coupled through two lenses without the need for fusion splicing, thereby reducing the optical signal loss caused by the connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the method for connecting a hollow core optical fiber and a solid core optical fiber of the present invention;

[0025] Figure 2 is a schematic cross-sectional view of a hollow core optical fiber;

[0026] Figure 3 is a schematic cross-sectional view of a solid core optical fiber;

[0027] Figure 4 Schematic diagram of the connection between hollow-core optical fiber and solid-core optical fiber.

[0028] In the figure: 1, solid core optical fiber; 2, first lens; 3, second lens; 4, hollow core optical fiber. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 are within the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly 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.

[0031] See also Figure 1 The present invention provides a method for connecting a hollow core optical fiber and a solid core optical fiber, comprising the following steps:

[0032] Determine the working wavelength, and obtain the mode field diameter, numerical aperture, and core refractive index data of the solid core fiber and hollow core fiber to be connected;

[0033] Select the type of lens to be used for connection;

[0034] Calculate the parameters of the first lens according to the working wavelength, the mode field diameter, numerical aperture, and core refractive index data of the solid core optical fiber; calculate the parameters of the second lens according to the working wavelength, the mode field diameter, numerical aperture, and core refractive index data of the hollow core optical fiber;

[0035] manufacturing the first lens and the second lens according to the parameters of the first lens and the parameters of the second lens;

[0036] The end of the solid core optical fiber is connected to the first lens, the end of the hollow core optical fiber is connected to the second lens, and the first lens is coupled to the second lens to connect the solid core optical fiber to the hollow core optical fiber.

[0037] Specifically, the operating wavelength is the wavelength of the transmitted optical signal.

[0038] The lens is any one of a self-focusing lens, a collimating lens, a fiber lens, and a metasurface lens. When the lens is a collimating lens, the lens material is N-SF11. The beam waist after the solid core fiber is connected to the first lens is the same as the beam waist after the hollow core fiber is connected to the second lens.

[0039] The method for connecting the hollow-core optical fiber and the solid-core optical fiber also includes a simulation step, which specifically includes: performing simulation tests on the coupled solid-core optical fiber, the first lens, the second lens and the hollow-core optical fiber to detect the loss caused by the coupling.

[0040] Specifically, the present application takes the connection between an ordinary single-mode optical fiber and a hollow-core optical fiber as an example to illustrate the method for connecting a hollow-core optical fiber with a solid-core optical fiber, which specifically includes the following steps:

[0041] Confirm that the operating wavelength is 1550nm, such as Figure 3 As shown, the solid core optical fiber 1 is a single-mode optical fiber, the mode field diameter of the solid core optical fiber 1 is 9.5um, and the core refractive index is 1.46. Figure 4As shown, the mode field diameter of the hollow core optical fiber 4 is 19.5 um, the core refractive index is 1, and the numerical aperture is 0.02.

[0042] The optical lens type selected is a collimator lens (C-Lens), and the material is N-SF11. That is, the first lens 2 and the second lens 3 are collimator lenses.

[0043] According to the solid core optical fiber 1, the hollow core optical fiber 4 and the type of the selected optical lens, the parameters of the lenses are calculated as follows: the parameters of the first lens 2 are: curvature radius 1.48, lens outer diameter 1mm, focal length 2mm, lens length 3.1mm, back focal intercept 0.22mm; the parameters of the second lens 3 are: curvature radius 0.79, lens outer diameter 1mm, focal length 1.06mm, lens length 1.7mm, back focal intercept 0.09mm. According to the calculated parameters of the first lens 2 and the second lens 3, the corresponding first lens 2 and the second lens 3 are manufactured.

[0044] Please continue reading Figure 2 , install the first lens 2 at the end of the solid core optical fiber 1, install the second lens 3 at the end of the hollow core optical fiber 4, and finally couple the first lens 2 and the second lens 3.

[0045] The coupling simulation of the coupled solid core fiber 1, the first lens 2, the second lens 3 and the hollow core fiber 4 shows that the theoretical coupling efficiency can reach 99.2% and the coupling loss is 0.0348 dB. The actual sample test shows that the connection loss is less than 0.24 dB.

[0046] The present application also discloses a hollow-core optical fiber and solid-core optical fiber connection structure, which is manufactured using the above-mentioned hollow-core optical fiber and solid-core optical fiber connection method. The hollow-core optical fiber and solid-core optical fiber connection structure includes a solid-core optical fiber 1, a first lens 2, a second lens 3 and a hollow-core optical fiber 4. The first lens 2 is connected to the end of the solid-core optical fiber 1, and the second lens 3 is connected to the end of the hollow-core optical fiber 4. The beam waist after the solid-core optical fiber 1 is connected to the first lens 2 is the same as the beam waist after the hollow-core optical fiber 4 is connected to the second lens 3, and the first lens 2 is coupled to the second lens 3.

[0047] The first lens 2 and the second lens 3 are any one of a self-focusing lens, a collimating lens, a fiber lens, and a metasurface lens. The first lens 2 is connected to the solid core optical fiber 1 by any one of bonding, snapping, and welding. The second lens 3 is connected to the hollow core optical fiber 4 by any one of bonding, snapping, and welding. The first lens 2 is connected to the first lens 2 by any one of bonding, snapping, and welding.

[0048] The present invention discloses a method for connecting a hollow-core optical fiber and a solid-core optical fiber. The method has good versatility and is applicable to the connection between solid-core optical fibers 1 and hollow-core optical fibers 4 of various specifications. The core refractive index, mode field directness, and numerical aperture of different optical fibers are converted into the same beam waist through an optical fiber lens, and then a high-coupling-efficiency connection is performed, thereby achieving ultra-low connection loss. The method of the present invention is simple, has a simple structure, and is easy to operate. The coupling efficiency of the optical fiber is very high, and a solution is provided for the application of the hollow-core optical fiber 4 in passive optical fiber devices.

[0049] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which are equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A method for connecting a hollow core optical fiber to a solid core optical fiber, characterized in that: The following steps are involved: Determine the working wavelength, and obtain the mode field diameter, numerical aperture, and core refractive index data of the solid core fiber and hollow core fiber to be connected; Select the type of lens to be used for connection; Calculate the parameters of the first lens according to the working wavelength, the mode field diameter, numerical aperture, and core refractive index data of the solid core optical fiber; calculate the parameters of the second lens according to the working wavelength, the mode field diameter, numerical aperture, and core refractive index data of the hollow core optical fiber; manufacturing the first lens and the second lens according to the parameters of the first lens and the parameters of the second lens; The end of the solid core optical fiber is connected to the first lens, and the end of the hollow core optical fiber is connected to the second lens. The first lens and the second lens are coupled to connect the solid core optical fiber and the hollow core optical fiber.

2. The method for connecting a hollow core optical fiber to a solid core optical fiber according to claim 1, characterized in that: The lens is any one of a self-focusing lens, a collimating lens, a fiber lens, and a super-surface lens.

3. The method for connecting a hollow core optical fiber to a solid core optical fiber according to claim 2, characterized in that: When the lens is a collimating lens, the lens material is N-SF11.

4. The method for connecting a hollow core optical fiber to a solid core optical fiber according to claim 1, characterized in that: The beam waist after the solid core optical fiber is connected to the first lens is the same as the beam waist after the hollow core optical fiber is connected to the second lens.

5. The method for connecting a hollow core optical fiber to a solid core optical fiber according to claim 1, characterized in that: The method for connecting the hollow-core optical fiber and the solid-core optical fiber also includes a simulation step, and the simulation step is specifically: performing a simulation test on the coupled solid-core optical fiber, the first lens, the second lens and the hollow-core optical fiber to detect the loss caused by the coupling.

6. A hollow-core fiber and solid-core fiber connection structure, manufactured by the hollow-core fiber and solid-core fiber connection method according to any one of claims 1 to 5, the hollow-core fiber and solid-core fiber connection structure comprising a hollow-core fiber and a solid-core fiber, characterized in that: The hollow-core optical fiber and solid-core optical fiber connection structure also includes a first lens and a second lens, the first lens is connected to the end of the solid-core optical fiber, the second lens is connected to the end of the hollow-core optical fiber, the beam waist after the solid-core optical fiber is connected to the first lens is the same as the beam waist after the hollow-core optical fiber is connected to the second lens, and the first lens is coupled to the second lens.

7. The hollow-core optical fiber and solid-core optical fiber connection structure according to claim 6, characterized in that: The first lens and the second lens are any one of a self-focusing lens, a collimating lens, a fiber lens, and a metasurface lens.

8. The hollow-core optical fiber and solid-core optical fiber connection structure according to claim 6, characterized in that: The first lens and the solid core optical fiber are connected by any one of bonding, snapping and welding.

9. The hollow-core optical fiber and solid-core optical fiber connection structure according to claim 6, characterized in that: The second lens and the hollow core optical fiber are connected by any one of bonding, snapping and welding.

10. The hollow-core optical fiber and solid-core optical fiber connection structure according to claim 6, characterized in that: The first lenses are connected to each other by any one of bonding, snapping and welding.

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