Amplification of a radially polarized laser beam using an Yb-doped double-clad fiber

Abstract

Amplification of a radially polarized laser beam is demonstrated by use of an Yb-doped double-clad fiber whose core cutoff wavelength for the LP11 mode is larger than the wavelength of the input beam. The beam power is amplified while maintaining the intensity and polarization distributions. The amplified spontaneous emission becomes negligible with increasing input power. The measured slope efficiency is 48%, and the output power is 1.1 W.