Transverse mode-wave length correlation adjustable all-fiber laser

Abstract

Provided is a transverse mode-wave length correlation adjustable all-fiber laser. A special corresponding characteristic between a wave length and a transverse mode of a less-mode fiber grating is utilized, a tunable band-pass filter is utilized to achieve changes of the resonant wavelength of the laser in an optical fiber resonant cavity, and therefore the output transverse mode is changed. The laser mainly comprises a pumping source, a gain medium, a wavelength division multiplexer, a reflecting mirror, the tunable band-pass filter, a mode coupling part and the less-mode fiber grating. The all-fiber laser has the advantages that mode fineness is high in outputting, a single wavelength is long, a linewidth is narrow, and the transverse mode is easy and convenient to switch. According to the all-fiber laser, no space coupled apparatus is arranged, the structure is more stable, and the all-fiber laser is convenient to move and produce.

Description

technical field [0001] The invention relates to the field of lasers, in particular to a fiber laser with adjustable transverse modes and a few-mode fiber grating. Background technique [0002] The output transverse mode characteristic of the laser has always been an important characteristic of the laser. In the early years, the main goal of the research on the transverse mode of the laser was the fundamental mode near the diffraction limit, which has the advantages of small spot, good directionality, and good linear polarization. Due to the properties of fiber waveguides, fiber lasers perform very well as single transverse mode lasers. In recent years, studies have shown that high-order mode lasers, especially first-order high-order mode lasers, have unique advantages in many aspects such as laser processing, optical manipulation, and particle acceleration. Therefore, research on high-order mode lasers has also developed rapidly. However, the output technology that integrat...

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Problems solved by technology

However, the output technology that integrates these two modes has rarely appeared. The existing variable mode field output technology mainly relies on the spatial phase modulator. In addition, this technology is mainly a passive conversion method of spatial structure, which has poor portability and stability is greatly affected by the input light source.

[0003] Chinese patent application CN102544999A discloses an axisymmetric polarized beam laser based on a few-mode fiber grating. This patent mainly uses the reflection of the few-mode fiber grating to the fundamental mode to output a laser beam with an angular or radially symmetrical polarization distribution. The disadvantage is that the output mode is fixed and cannot be switched between the fundamental mode and the first-order mode

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