Large mode field diameter negative refractive index mono-mode glass fiber

A glass fiber, negative refractive index technology, applied in graded index core/clad fiber, clad fiber, optical waveguide light guide, etc., can solve problems such as difficult high-power output

Inactive Publication Date: 2008-06-18
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Generally, the core diameter of a single-mode fiber is only 8-10 μm, and it is difficult to achieve higher power output

Method used

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  • Large mode field diameter negative refractive index mono-mode glass fiber
  • Large mode field diameter negative refractive index mono-mode glass fiber

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Experimental program
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Embodiment 1

[0014] Embodiment 1: FIG. 1 is a schematic diagram of the cross-sectional refractive index distribution of the large mode field diameter double-clad single-mode optical fiber of the present invention, and the core refractive index of the optical fiber is N 1 , the refractive index distributions of the inner and outer cladding are respectively N 2 and N 3 , and satisfy the relation: N 2 ≥N 1 and N 2 >N 3 , the refractive index changes stepwise at the interface between the core and the inner cladding and the inner cladding and the outer cladding. The fiber core composition is phosphate glass, and its composition is: 70P 2 o 5 -8Al 2 o 3 -15BaO-4La 2 o 3 -3Nd 2 o 3 , where Nd 3+ The concentration is 8.4×10 19 ions / cm 3 . The doping concentration of rare earth ions varies with the direction of the core radius as shown by the dotted line in Fig. 1 . The core and inner and outer cladding materials of the optical fiber can be made of phosphate glass or other types of...

Embodiment 2

[0016] Embodiment 2: Figure 2 is a schematic diagram of the cross-sectional refractive index distribution of the large mode field diameter double-clad single-mode fiber of the present invention, which is similar to Embodiment 1 and satisfies the relationship N 2 ≥N 1 and N 2 >N 3 . The concentration of doping ions changes gradually along the radial direction, and the concentration is highest at the center of the fiber core, as shown by the dotted line in Fig. 2 . The advantage of this structure is that because the concentration of ions at the interface between the core and the inner cladding is low, the gain coefficient is small and the refractive index change caused by the gain is small. In an optical fiber, the high-order modes are generally distributed at the interface between the fiber core and the cladding, where the effective waveguide structure cannot be formed, further suppressing the generation of high-order modes. In this structure, a single-mode laser output wit...

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PUM

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Abstract

The invention discloses a large mode field diameter and negative refractive index single mode glass fiber. The glass fiber comprises a fiber core, an inner cladding and an outer cladding; the refractive index of the fiber core is N1, the refractive indexes of the inner cladding and the outer cladding are respectively N2 and N3, which satisfy the relation: N2 is more than or equal to N1 and N2> N3; the lumination ion is mixed into the fiber core, which is the lanthanum ion or the combination of one or several transition metal ions; the mixing concentration is more than 1*1019 ions / cm3. The glass fiber of the invention forms the wave guiding structure between the fiber core and the inner cladding under the common function of the plus refractive index and the wave guiding refractive index; the laser oscillates stably in the fiber core. The invention realizes the large mode field diameter single mode laser output in the fiber.

Description

technical field [0001] The invention relates to a glass optical fiber, in particular to a single-mode glass optical fiber with a large mode field diameter and a negative refractive index. Background technique [0002] With its excellent mode, fiber laser has broad application prospects in industry, agriculture, military, medical and other fields. Especially in the fields of laser cutting and welding, high-power and high-energy lasers are particularly important. To increase the power or energy of the laser output from the fiber, it is necessary to use a fiber with a large mode field diameter. Generally, the core diameter of a single-mode optical fiber is only 8-10 μm, and it is difficult to achieve higher power output. [0003] At present, the commonly used large mode field diameter fiber mostly adopts the high-order mode leakage scheme, that is, the high-order mode generated in the fiber leaks out of the fiber by bending the fiber or designing the fiber structure, such as p...

Claims

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Application Information

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IPC IPC(8): G02B6/02G02B6/028
Inventor 杨中民徐善辉张勤远
Owner SOUTH CHINA UNIV OF TECH
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