KR100703108B1 - Optical fiber - Google Patents

Abstract

An optical fiber comprising a core, a first cladding layer surrounding a core, and a second cladding layer surrounding a first cladding layer, wherein the first cladding layer is an air layer of a predetermined shape.

Core, cladding layer, air layer, bending loss, optical fiber.

Description

Optical fiber {OPTICAL FIBER}

Figure 1 shows a cross-sectional structure cut the optical fiber according to an embodiment of the present invention.

FIG. 2 is a graph showing a result of measuring bending loss according to a bending radius by comparing an optical fiber of FIG. 1 with a conventional optical fiber.

3A is a graph showing a transmission spectrum according to the number of bending of the optical fiber of FIG. 1.

3B is a graph showing bending loss according to the number of bending of the optical fiber of FIG. 1.

<Description of Drawing>

100: optical fiber 110: core

120: first cladding layer 130: second cladding layer

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to optical fibers, and more particularly, to minimize bending loss in a communication environment with many bending of optical fibers such as FTTH (Fiber To The Home) communication or metro communication. Thereby, the present invention relates to an optical fiber for improving the efficiency of an optical communication system.

:relative refractive index difference)가 0.3% 정도로 낮아 구부림에 약하여 높은 굽힘 손실을 유발하는 단점이 있었다. 이러한 굽힘 손실을 억제하기 위하여 코어와 클래딩층 사이의 굴절률을 높여서 코어로 전달되는 광 신호가 높은 유효 굴절률을 유지하며 구부림에 대해서도 광 신호의 가둠(confinement)을 높게 유지하도록 하여 굽힘 손실을 최소화하는 방법을 사용하였다.The general optical fiber is composed of a high refractive index core and a low refractive index cladding layer, and transmits an optical signal based on a total reflection principle due to a difference in refractive index between the core and the cladding layer. However, the refractive index difference between the core and the cladding layer (

The: relative refractive index difference (0.3%) was low at about 0.3%, causing weak bending and causing high bending loss. In order to suppress the bending loss, the refractive index between the core and the cladding layer is increased, so that the optical signal transmitted to the core maintains a high effective refractive index and the confinement of the optical signal is high even when bending to minimize bending loss. Was used.

However, this conventional method has a problem in that the wavelength region for operating in a single mode becomes narrow and the size of the core decreases, thereby increasing insertion loss. Photonic crystal optical fibers form a regular air layer inside the optical fibers in place of the core and the cladding layers, thereby enhancing the band gap effect and transferring optical signals with low bending loss. However, in order to arrange the air layer regularly and maintain the arrangement structure, high technical power is required. In addition, a method of reducing bending loss by minimizing the influence of the optical fiber on the bending even if the bending occurs by inserting a new material to increase the area in the cabling of the optical fiber has been proposed. There is a problem that the optical fiber laying efficiency is low.

Accordingly, an object of the present invention is to provide an optical fiber that can operate in a single mode in a wide wavelength band and can efficiently transmit an optical signal by minimizing bending loss.

In order to achieve this object, the optical fiber according to the present invention comprises a core, a first cladding layer surrounding the core, and a second cladding layer surrounding the first cladding layer, wherein the first cladding layer is It is an air layer of a predetermined shape.

Preferably, the first cladding layer is formed of at least one air layer. The air layer has a shape of a grapefruit shape, a round shape, an oval shape, or a taegeuk pattern. The air layer is filled with a predetermined substance. The material includes a liquid crystal or a thermal-optic polymer. The difference in refractive index between the core and the second cladding layer is substantially 0.001 to 2.0%. The core comprises silica, germanium, boron, erbium, yttrium, aluminum, a polymer, or an air layer. The refractive index of the second cladding layer is relatively lower than the refractive index of the core. The second cladding layer includes silica, fluorine or silica added with boron, or a polymer. The radius of the core is substantially 0.5um to 25um. The distance between the core center and the center of the first cladding layer is substantially 0.5um to 60um. The thickness of the first cladding layer is substantially 10.0um to 60.0um.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 schematically shows a cross-sectional structure cut the optical fiber according to an embodiment of the present invention.

Referring to FIG. 1, a core 110, a first cladding layer 120 surrounding the core 110, and a second cladding layer 130 surrounding the first cladding layer 120 may be included. One cladding layer 120 is an example of an optical fiber that is an air layer of a predetermined shape.

The core 110 maintains high refractive index, including germanium (Ge), boron (B), erbium (Er), yttrium (Yb), aluminum (Al), silica (silica), polymer, or air layer do. In addition, the radius R _core of the core 110 is substantially 0.5um to 25um.

)가 실질적으로 1.46%의 높은 값을 가지므로 코어(110)에서의 광 신호의 가둠 효과가 증가할 수 있다. 또한, 제1 클래딩층(120)에서 공기층으로 인해 밴드갭 효과가 발생하며, 이에 따라 코어(110)에서 광 신호의 가둠 효과가 더욱 증가할 수 있다.The first cladding layer 120 is formed of at least one air layer, and the shape of the air layer is preferably one of a grapefruit shape, a round shape, an ellipse, and a taegeuk pattern, but is not particularly limited thereto. . The refractive index difference between the core 110 and the first cladding layer 120 having the air layer (

) Has a substantially high value of 1.46%, thereby increasing the confinement effect of the optical signal in the core 110. In addition, a band gap effect occurs due to the air layer in the first cladding layer 120, and thus the confinement effect of the optical signal may be further increased in the core 110.

Therefore, the optical fiber 100 according to the present embodiment shows the characteristics of the general optical fiber and the photonic crystal optical fiber together. That is, by simultaneously providing the total reflection condition and the band gap effect, the confinement effect of the optical signal in the core 110 is good, so that the bending loss can be minimized even when the optical fiber 100 is bent to a predetermined radius.

In addition, the thickness (d _gap ) of the first cladding layer 120 is preferably 10.0um to 60.0um, and the distance between the center of the core 110 and the center of the first cladding layer 120 is substantially 0.5um to It is preferable that it is 60um.

Meanwhile, the air layer may be filled with a material including a liquid crystal or a thermal-optic polymer.

The refractive index of the second cladding layer 130 is preferably lower than the refractive index of the core 110, and the difference in refractive index between the core 110 and the second cladding layer 130 is preferably 0.001% to 2.0%. Do. In addition, the second cladding layer 130 preferably includes silica, fluorine or silica to which boron is added, or a polymer.

FIG. 2 is a graph showing a result of measuring bending loss according to a bending radius by comparing an optical fiber of FIG. 1 with a conventional optical fiber.

2, the horizontal axis represents the bending radius (5mm to 15mm) of the optical fiber according to the present embodiment, the vertical axis represents the bending loss (dB / turn). The conventional single mode optical fiber can be seen that the bending loss increases rapidly in the area where the bending radius is 10mm, it can be seen that the optical fiber according to this embodiment is not affected by the bending radius. In other words, since a large difference in refractive index between the core and the first cladding layer improves the confinement effect of the optical signal in the core, the bending loss can be maintained at 0.06 dB or less even if the bending radius of the optical fiber is 5 mm.

Figure 3a is a graph showing the transmission spectrum according to the number of bending experiments using the optical fiber of Figure 1, Figure 3b is a graph showing the bending loss according to the number of bending experiments using the optical fiber of FIG.

Referring to FIG. 3A, the horizontal axis represents wavelength of an optical signal [nm] and the vertical axis represents transmission power [dBm]. It can be seen that the optical fiber according to the present embodiment maintains a constant transmission power even when the number of bending increases in the wavelength band of 500 nm to 1800 nm. Accordingly, the optical signal can be effectively transmitted in a single mode regardless of the number of bending or bending.

Referring to FIG. 3B, the bending loss according to the bending frequency change in the wavelength band of 1550 nm shows that the optical loss slightly increases as the number of bending increases, but it shows that the bending characteristic is generally strong.

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

According to the present invention, it is possible to effectively transmit the optical signal in a wide wavelength band and there is an effect that can minimize the bending loss according to the degree of bending in a single mode.

In addition, there is an effect that can effectively implement a high-speed optical communication system by minimizing the distortion of the optical signal during transmission and improving the loss characteristics.

Furthermore, simple structural and easy property control improves productivity, facilitates mass production and integration of optical elements, and provides optical signals in harsh environments where optical fiber bends are required in FTTH systems. There is an effect that can be delivered effectively.

Claims (12)

A core comprising germanium, boron, erbium, yttrium, aluminum, a polymer, or an air layer, A first cladding layer surrounding the core; A second cladding layer surrounding the first cladding layer, The first cladding layer is at least one air layer of a predetermined shape having a thickness of 10.0um to 60.0um, the distance between the core center and the center of the first air layer is substantially 0.5um to 60um. delete The method of claim 1, The air layer has a shape of grapefruit (grapefruit) form, circular, oval, taiji pattern form of any one of the optical fibers. The method of claim 1, The optical fiber is filled with a predetermined material in the air layer. The method of claim 4, wherein The material comprises a liquid crystal or a thermal-optic polymer. The method of claim 1, The refractive index difference between the core and the second cladding layer is substantially 0.001% to 2.0% optical fiber. delete The method of claim 1, The refractive index of the second cladding layer is relatively lower than the refractive index of the core. The method of claim 8, The second cladding layer comprises silica, fluorine, or boron-added silica, or an optical fiber. The method of claim 1, And the radius of the core is substantially 0.5um to 25um. delete delete

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