RESUMEN
An all-normal dispersion fiber laser mode-locked by nonlinear polarization evolution is presented in this paper. A magneto-optical polarization controller is employed in a fiber laser to optimize the polarization state and mode-locking operation. In order to provide an adjustable and large enough magnetic field for magneto-optical crystals, a magnetic yoke is designed with silicon steel and copper coil. The Q-switched and continuous-wave mode-locking regime of the fiber laser are investigated experimentally. At a pumping power of 2.08 W, the laser can generate stable mode-locking pulses with an average power of 213 mW. The repetition rate and the pulse duration are 63.7 MHz and 6.2 ps, respectively, corresponding to a pulse energy of 3.34 nJ and a peak power of 539 W. The laser can operate continuously in mode-locking states over five hours with almost no variation in pulse profile, optical spectrum, and output power.
RESUMEN
We propose a cross-splicing method, for the first time to our knowledge, to compensate the effect of fiber birefringence in a polarization-maintaining fiber ring laser mode locked by nonlinear polarization evolution. This method has been investigated numerically and experimentally. The results indicate that stable mode-locking pulses can be obtained in the cavity with this method; otherwise, no mode-locking states are achieved. The design processes of the laser cavity are presented. Pulses with single pulse energy of 2.1 nJ are generated at pump power of 460 mW. The spectral bandwidth and pulse duration are 17.5 nm and 11.7 ps, respectively. The tunability of the laser is also studied. The central wavelength can be tuned from 1023.2 to 1045.9 nm.