A method of detecting mode hopping for single-longitudinal-mode (SLM) fiber ring lasers has been proposed and experimentally demonstrated. The method that is based on an unbalanced Michelson interferometer (MI) utilizing phase generated carrier modulation instantly transforms mode-hopping dynamics into steep phase changes of the interferometer. Multiform mode hops in an SLM erbium-doped fiber ring laser with an 18.6 MHz mode spacing have been detected exactly in real-time domain and discussed in detail. Numerical results show that the MI-based method has a high testing sensitivity for identifying mode hopping, which will play a significant role in evaluating the output stability of SLM fiber lasers.
© 2012 Optical Society of America
Lasers and Laser Optics
Original Manuscript: June 29, 2012
Revised Manuscript: September 22, 2012
Manuscript Accepted: September 22, 2012
Published: October 19, 2012
Mingxiang Ma, Zhengliang Hu, Pan Xu, Wei Wang, and Yongming Hu, "Detecting mode hopping in single-longitudinal-mode fiber ring lasers based on an unbalanced fiber Michelson interferometer," Appl. Opt. 51, 7420-7425 (2012)