Multi-core nonlinear optical fiber

Abstract

The invention relates to a multi-core nonlinear optical fiber. The multi-core nonlinear optical fiber comprises three or more fiber cores, an air cladding layer and a pure quartz glass cladding layer, wherein the air cladding layer includes an inner air cladding layer and an outer air cladding layer; the inner air cladding layer is composed of inner air holes in an inter lattice; the outer air cladding layer is composed of outer air holes in an outer lattice; the inner lattice is a regular hexagonal lattice including a center point; the outer lattice is a regular hexagonal lattice surrounding the inner lattice; the center distances between any two neighboring points in both the inner lattice and the outer lattice are equal to each other; the inner air holes are distributed in all points of the inner lattice except for the points for distributing the fiber cores; the fiber cores are symmetrically distributed around the center point; the center distances between any two neighboring fiber cores are equal to each other; the outer air holes are distributed in all points of the outer lattice. The multi-core nonlinear optical fiber provided by the invention solves the problem of low-loss connection between a large-core-diameter tail fiber of a high-power fiber laser and a nonlinear microstructure fiber, can bear higher pumping power and can realize dispersion characteristics of optical fibers more effectively.

Description

technical field [0001] The invention relates to a multi-core nonlinear optical fiber, belonging to the technical field of optical fibers. Background technique [0002] Microstructured optical fiber is a relatively new optical fiber structure. Its cladding contains an array of air holes arranged along the axis of the fiber. By adjusting the pitch of the air hole array (the distance between the centers of adjacent air holes), the duty cycle (or air filling rate) can effectively change the nonlinear coefficient and dispersion characteristics of the fiber. For example, the zero dispersion wavelength of the fiber can be adjusted to around 1 μm, which is exactly at the output wavelength of the usual picosecond mode-locked ytterbium-doped fiber laser. nearby. Existing studies (REVIEWS OF MODERN PHYSICS, VOLUME 78, P1135-1184, OCTOBER–DECEMBER 2006) have shown that when the output wavelength of the Yb-doped fiber laser is within the anomalous dispersion region of the microstructure...

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Problems solved by technology

[0004] But there is a problem: the microstructure fiber used is designed with a single core. In order to design the zero dispersion point around 1 μm, the core diameter is usually less than 5 μm, while the core diameter of the ytterbium-doped fiber reaches around 30 μm.

[0007] Chinese patent (Application No. 200810053629.7) discloses a small core-diameter bundled large effective area and highly nonlinear photonic crystal fiber. The core diameter of a single core is about 1-2 μm, which is beneficial to adjust the zero-dispersion wavelength of the fiber. Near 800nm, but not conducive to the application of supercontinuum lasers with a working wavelength of 1 μm; and its smaller core diameter is also not conducive to bearing higher pump power; considering its specific invention content and embodiments and drawings, its internal and external The pitches of the large and small air holes are inconsistent. In fact, the invention cannot guarantee the consistency of the pitches of the inner and outer air claddings, which brings substantial difficulties to its actual preparation. Finally, the invention does not address how to realize single-mode Output does not make any description, but to ensure that the output mode of the multi-core microstructured fiber is single mode is necessary for the application of supercontinuum laser

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