Self-Q-switch and CW Operation of a tunable dual-wavelength Er/Yb double-clad fiber laser

Abstract

In this paper, a double-clad Er/Yb fiber laser with self-Q-switched and continuous wave operation depending on the pump power range is experimentally demonstrated. The linear cavity is formed on one side by a pair of cascaded tunable fiber Bragg gratings used for the selection and tuning of the generated laser lines. On the opposite side, a fiber optical loop mirror with high birefringence fiber in the loop is used to adjust the intra-cavity losses to obtain dual-wavelength emission by temperature changes on the fiber loop. Continuous wave dual-wavelength laser operation is obtained for tunable separation of the generated laser lines in a range from 1 to 7 nm, maximum output power of 3.6Wwith a pump power of 10Wand laser wavelengths linewidth of ~0.2 nm. Self-Q-switched laser pulses are obtained with low pump power in a range from 322 to 890 mW. Q-switched pulses with minimum pulse duration of ~1.5 μs and maximum pulse energy of ~3.5 μJ are obtained.