Double-cladding optical fiber with Bragg structure, optical fiber amplifier and optical fiber laser

Abstract

The invention relates to a double-cladding optical fiber with a Bragg structure, comprises a fiber core 1, an inner cladding layer 2, an outer cladding layer 3 and a protection layer 4, wherein a radial coaxial Bragg structure region with high-low refractive index layers, which are periodically distributed in an overlapping way, is arranged on the inner cladding layer 2. The double-cladding optical fiber has large core diameter and low NA value, realizes the high-power laser ground mode output under the condition of not increasing the size of the inner cladding layer by providing pumping light for the optical fiber, and amplifying and propagating signals passing through the optical fiber, facilitates heat management while high-power laser is output and is suitable for manufacturing a high-power and high beam quality optical fiber laser and an optical fiber amplifier.

Description

technical field [0001] The invention relates to an optical fiber amplifier, an optical fiber laser, and a double-clad optical fiber with a Bragg structure as an optical amplification medium, belonging to the fields of optical fiber amplifiers, optical fiber lasers, and special optical fibers. Background technique [0002] Fiber lasers and fiber amplifiers usually use core pumping technology. The initial gain fiber adopts a common single-clad structure, and active ions are doped in the fiber core as the gain medium. Both pump light and signal light are transmitted in the fiber core. , so the pump light must be efficiently coupled into the fiber core. Since the diameter of the fiber core is only a few microns, the coupling efficiency with the pump source is low, so that the laser output power is also very low, which limits its application range. In order to improve the output power of fiber lasers, a double-clad fiber is proposed, that is, an inner cladding is introduced betw...

AI Technical Summary

Problems solved by technology

However, the reduction of the NA value greatly reduces the binding force on the mode of the excited light in the fiber core, and the laser mode will extend to the inner cladding, which will cause the size of the inner cladding to expand, which will cause the following problems: (1) The thermal conductivity is reduced , losing the biggest advantage of good thermal conductivity of the fiber laser; (2) the flexibility of the fiber is reduced, which increases the manufacturing cost; (3) when the fiber is squeezed and bent, it is prone to mode leakage, which affects the stability of the output laser. poses problems for practical applications of fiber lasers and fiber amplifiers

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