Large-mode-area active optical fiber and preparation method thereof

Abstract

The invention provides a large-mode-area active optical fiber, which comprises a fiber core, a first cladding, a second cladding and a third cladding, wherein the first cladding, the second cladding and the third cladding sequentially encircle the periphery of the fiber core; the effective refractive index of the second cladding is lower than the effective refractive indexes of the first claddingand the fiber core; a pump core area encircles the outer side of the third cladding; an external cladding encircles the outer side of the pump core area and comprises a layer of air vent holes or capillary bars doped with quartz glass; and the effective refractive index of the external cladding is lower than that of the pump core area. On the premise of ensuring a large mode area of the active optical fiber, the optical fiber suppresses amplified spontaneous radiation, improves the stability of the optical fiber, and ensures the quality of light beam. The invention also provides a preparationmethod of the active optical fiber. By adopting a liquid phase multi-point doping mode of gas-phase aluminum doping and rare-earth ions, continuous doping for many times can be flexibly controlled and realized, the size of a rare-earth doped core bar is greatly increased, and uniform doping of the rare-earth ions and aluminum is simultaneously realized.

Description

technical field

[0001] The invention relates to an active optical fiber and a preparation method thereof, in particular to an active optical fiber with large mode field and high beam quality and a preparation method thereof. Background technique

[0002] As the main gain medium, active fiber plays a vital role in fiber lasers and amplifiers. The development and progress of active fibers directly promote the process of fiber lasers and amplifiers.

[0003] From the original core-pumped fiber laser, due to the limitation of pump power, after Snitzer et al. proposed a double-clad laser fiber in 1988, cladding-based pump lasers have developed rapidly, and countries around the world have successively realized single-fiber output The power exceeds the kW level, but as the output power continues to increase, the problems of the active fiber itself are becoming more and more obvious, and the impact on the performance of the laser is becoming more and more serious.

[0004] Therefor...

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