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Passively Q-switched erbium fiber ring laser with nonlinear polarization rotation

An all-fiber passively Q-switched erbium fiber ring laser with nonlinear polarization rotation is experimentally demonstrated. By incorporating a length of single mode fiber and polarization dependent isolator into the erbium fiber ring laser, intensity dependent transmission can be implemented due to nonlinear polarization rotation, which can act as an artificial saturable absorber for switching. Such a passively Q-switched erbium fiber ring laser has the simple and all-fiber configuration. In addition, passive harmonic mode-locking and chaotic pulses are also generated from the erbium fiber ring laser.