All-Fiber Laser Beam Shaping at 1.0 μm Wavelength Regionin a Single-mode Fiber

摘要

Laser beam shaping is an important subject in industrial and medical applications of lasers since different applications may require different laser intensity distributions. Recently we demonstrated successfully an all-fiber laser beam shaping device that could transform a Gaussian shaped laser beam into a uniform or ring-shaped beam in 1.5 μm wavelength region. In this paper we present the work of the beam shaping in 1.0 μm wavelength region to make it compatible to Yb-doped high power fiber laser. The device uses a long-period grating to couple a portion of core-mode, LP_(01) into a low-order mth-radial cladding mode LP_(0m). Interference of the two modes could reduce field at the centre and enhance the field in the first or second ring of the cladding mode to transform the Gaussian-shaped laser beam to an intensity uniform beam. The design parameters that affect the beam shaping will be discussed and the results of the interference from two cladding modes, LP_(03) and LP_(04) will be presented.