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Air hole square array fiber core annular doping four-core photonic crystal fiber

A photonic crystal fiber and air hole technology, applied in the direction of cladding fiber, optical waveguide light guide, etc., can solve the problems of easily damaged fiber end face, limited mode area, refractive index reduction, etc., so as to improve the thermal damage threshold and increase the mode area. , the effect of limiting loss reduction

Inactive Publication Date: 2012-12-12
YANSHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Studies have shown that doping the silica core of photonic crystal fiber, doping ZrO 2 、TiO 2 、Al 2 o 3 、GeO 2 ,P 2 o 5 Such materials can increase the refractive index of quartz glass (high doping), doping B 2 o 3 , F and other raw materials can reduce the refractive index of silica glass (low doping), and the doped fiber can obtain a larger mode area, but at present this doping technology is only limited to single-core fiber, which limits the mode area. Further improve
If a multi-core fiber is used, although a larger mode field area can be obtained compared with a single-core fiber, from the perspective of each fiber core, the output beam is a traditional Gaussian beam. When the pump light power is large, It is easy to damage the fiber end face

Method used

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  • Air hole square array fiber core annular doping four-core photonic crystal fiber
  • Air hole square array fiber core annular doping four-core photonic crystal fiber
  • Air hole square array fiber core annular doping four-core photonic crystal fiber

Examples

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Embodiment 1

[0019] exist figure 1 In the cross-sectional view of the photonic crystal fiber shown in Embodiment 1 of the present invention, the fiber is mainly composed of a core and a cladding. Wherein, there are 13'13-3'3'4=133 air holes 2 in a uniform square array in the optical fiber cladding 1, the diameter of the air holes is d=4 μm, and the distance between two holes Λ=10 μm. Four groups of units lacking 3'3 air holes constitute the core, and the four cores are symmetrically distributed on the diagonals of the four quadrants. Each fiber core includes an inner core 3 and a doped annular region 4, wherein the inner core is made of quartz with a radius of ra=6μm, and the highly doped annular region wrapped outside the inner core is quartz-based doped with a molar percentage It is 4.25% germanium dioxide, which makes its refractive index 1.4504, which is slightly higher than the refractive index of 1.45 of the quartz inner core. The thickness of the highly doped annular region is the...

Embodiment 2

[0023] Example 2 of the present invention is basically the same as Example 1, except that the molar percentage of doped germanium dioxide is reduced to 4.11% (corresponding to a refractive index of 1.4502), and the relationship between the effective mode area and confinement loss with wavelength is as follows Figure 4 shown. It can be seen from the figure that, compared with the fiber in Example 1, the optical fiber has a smaller effective mode area and higher confinement loss. At λ=1.55 μm, its effective mode area is 2934 μm 2 , the limiting loss is 1.42′10 -4 dB / km.

Embodiment 3

[0025] Example 3 of the present invention is basically the same as Example 1, except that the molar percentage of doped germanium dioxide is increased to 4.38% (corresponding to a refractive index of 1.4506), and the relationship between the effective mode area and confinement loss with wavelength is as follows Figure 5 shown. It can be seen from the figure that the optical fiber has a larger effective mode area and lower confinement loss than the optical fiber of the first embodiment. At λ=1.55 μm, its effective mode area is 3244 μm 2 , the limiting loss is 1.32′10 -6 dB / km.

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Abstract

The invention relates to an air hole square array fiber core annular doping four-core photonic crystal fiber, which comprises a fiber cladding and fiber cores, wherein the fiber cladding is formed by distributing a plurality of layers of air hole square arrays; the fiber core is formed by four groups of units lack of air holes; and the four fiber cores are symmetrically distributed at diagonal lines of four quadrants. Each fiber cores comprises an inner core and a doping annular area, wherein the inner core and the fiber cladding are made of quartz materials, and the doping annular area wrapped outside the inner core is made of quartz doped with an oxide capable of increasing a refractive index, so that the refractive index of the doping annular area is a little higher than that of the fiber core. With the adoption of the fiber core annular doping four-core structure, the mode area can be efficiently increased, and the nonlinear effect can be reduced. The fiber core annular doping can form a flat mode field, thereby efficiently reducing the thermal damage effects of the fiber. The fiber cladding is formed by distributing the plurality of layers of air hole square arrays, so that the ultralow limit loss can be realized, and the energy loss can be greatly reduced in the transmitting process.

Description

technical field [0001] The invention relates to a circularly doped four-core photonic crystal fiber with a square array of air holes, in particular to a photonic crystal fiber with a flat-top mode field, a large mode area and ultra-low confinement loss, and belongs to the field of optical fiber technology. Background technique [0002] Due to its advantages in efficiency, heat dissipation and beam quality, high-power fiber lasers have broad application prospects in the fields of industrial processing, medical treatment and national defense. However, nonlinear effects such as Raman scattering, Brillouin scattering, and four-wave mixing limit the further improvement of the output power of high-efficiency fiber lasers. There is a great relationship between the nonlinear effect and the light intensity. By increasing the mode area of ​​the fiber, the light intensity can be effectively reduced, thereby inhibiting the nonlinear effect. Photonic crystal fiber (PCF), also known as m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B6/02
Inventor 李曙光张晓霞
Owner YANSHAN UNIV
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