Fiber optic power laser device

Abstract

The invention relates to a fiber optic power laser device comprising a power laser diode (1) emitting a pump wave, an optical resonator (12) comprising a totally reflecting end (6) and a partially reflecting end (9), an amplifying multimode optic fiber (7) and optical means (3, 11) coupling said pump wave in the multimode optical fiber (7). According to the invention, the optical resonator (12) comprises at least one optical sub-module (25, 26) consisting of a spatial filtering means and comprising optical means (2, 8) having a specific position in the optical sub-module (25, 26) so as to make the optical sub-module able to reproduce in amplitude and phase, after a round trip of the laser beam in said sub-module, the fundamental mode of the multimode optical fiber (7) on the input or output face (23, 24) of said multimode optical fiber (7), minimizing the losses of the fundamental mode, and so as to make the optical sub-module capable of filtering the other modes by producing in the optical resonator additional losses on said modes, minimizing the number of laser modes being propagated in the optical resonator.

Description

technical field [0001] The invention relates to a power laser device for generating spatially single-mode radiation from a multimode fiber. Background technique [0002] Single-mode radiation refers to radiation whose divergence is close to the minimum due to diffraction of the light intensity distribution profile of said radiation. [0003] A solid-state laser includes at least one amplifying medium and an optical resonator formed by a set of mirrors. The spatial characteristics of the output beam are given by the properties of the resonator. [0004] In particular, it can be shown that if the resonator is such a stable resonator, the beam shape can be resolved from the Hermite-Gauss function. These functions are called cavity modes. [0005] Among these modes, the matrix has a Gaussian shape and minimal divergence. Because the archetype can achieve minimum focus, it is often selected by users. However, the excited region in the amplifying medium has an intrinsic size ...

AI Technical Summary

Problems solved by technology

[0023] However, this method inevitably suffers from the loss of the fundamental mode and is difficult to realize on short fibers because it requires multiple windings with a diameter between 5 and 15 cm, which corresponds to a fiber length greater than 1 m

[0024] Besides that, the presence of several modes in the radiation produced by the fibers makes it difficult or even impossible to obtain polarized radiation

[0025] Currently, there is no suitable solution for fiber lasers capable of obtaining single-mode with large lateral dimensions without threatening fiber lifetime

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