Radially polarized and passively Q-switched fiber laser

We report, for the first time to our knowledge, a radially polarized and passively Q-switched Yb-doped fiber laser. By using a Cr4+:YAG crystal as a saturable absorber and a photonic crystal grating as a polarization mirror, a radially polarized pulse is produced, which has 202 W of peak power, 75 ns duration, and similar to 92% polarization purity at a 56: 6 kHz repetition rate. The Q-switched pulse with radial polarization from the fiber laser would facilitate numerous applications. (C) 2010 Optical Society of America