Efficient repetitive passive Q switching of a cladding-pumped Er–Yb fiber laser has been demonstrated by use of an external-cavity configuration containing a Co<sup>2+</sup>: ZnS crystal as a saturable absorber. Energies of as much as 60μJ in pulses of durations as short as 3.5 ns (FWHM), corresponding to a peak power of >10kW, have been generated, and the maximum slope efficiency with respect to the absorbed pump power was 13%. Using a bulk diffraction grating in the Littrow configuration to provide wavelength-selective feedback, we tuned the passively Q -switched fiber laser over 31 nm from 1532 to 1563 nm. The prospects for further improvement in performance are discussed.
© 2002 Optical Society of America
(060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
(140.3480) Lasers and laser optics : Lasers, diode-pumped
(140.3510) Lasers and laser optics : Lasers, fiber
(140.3540) Lasers and laser optics : Lasers, Q-switched
(140.3600) Lasers and laser optics : Lasers, tunable
M. Laroche, A. M. Chardon, J. Nilsson, D. P. Shepherd, W. A. Clarkson, S. Girard, and R. Moncorgé, "Compact diode-pumped passively Q-switched tunable Er-Yb double-clad fiber laser," Opt. Lett. 27, 1980-1982 (2002)