Q-switching fiber laser based on carbon nano-tube for cylindrical-vector beams generation

摘要

An all fiber passive Q-switching laser with cylindrical-vector beam (CVB) output was demonstrated for the first time to the best of our knowledge using carbon nano-tube (CNT) as saturable absorber and a few-mode fiber Bragg grating as polarization-selective output coupler. The fiber laser operated at the wavelength of 1557.5 nm with a narrow linewidth of less than 0.02 nm (3 dB). Attributed to the high damage threshold and polarization insensitivity of the CNT, the Q-switching fiber laser was capable of generating switchable radially or azimuthally polarized output modes. When the pump power varied from 63.09 to 162.63 mW the repetition rate of the Q-switching CVB fiber laser increased three times from 30.88 to 92.75 kHz.