Mode regulation-based beam shaping

A structure for beam shaping with mode regulation is proposed in this paper. Mode conversion is realized by few-mode long-period fiber gratings to obtain different modes. The frequency-selecting and reflection of the fundamental mode beam are achieved by single-mode fiber Bragg gratings . Few-mode fiber Bragg gratings are employed to reflect different mode beams. By combining single-mode fiber Bragg gratings and few-mode fiber Bragg gratings to form linear resonators , lasing under LP 01 , LP 11 , and LP 21 modes is realized. Through regulating the beam of LP 01 , LP 11 , and LP 21 modes, this approach enables the output of the Gaussian beam , donut beam, and flat-top beam. • A structure for beam shaping with mode regulation is proposed. • The Gaussian beam, donut beam, and flat-top beam are output by mode regulation. • Fiber gratings are used to achieve mode coupling at the same wavelength.