Abstract:For the first time we have suggested and realized passive Q-switched Yb-doped fiber laser with a saturable absorber based on Ho-doped fiber laser. The pulse duration was of 250 ns, the pulse energy -70 μJ, the peak power -300 W. The laser is perspective for technology processes. Possible ways of laser characteristics improving are discussed. At present CW Yb-doped fiber lasers [1] have found different applications. Q-switched fiber lasers due to high pulse energy allow one to increase a number of applications including medicine, material processing, range finding etc. Q-switched oscillation can be obtained using outer electro-or magnetomechanical devices [2,3], however all fiber pulsed lasers are of special interest since they keep all advantages of fiber lasers, namely compactness, absence of mechanical elements, long time stability etc. Up to now several schemes of such lasers were proposed and realized. One of them is self Q-switched fiber laser where to avoid CW lasing, a continuous feedback is suppressed by the isolation of the output laser end. In this scheme lasing is provided by the input Bragg grating and dynamic feedback caused by stimulated Brillouin scattering [4,5] or Rayleigh scattering [6]. Output energy of 0.17 mJ was achieved when the additional amplification of the laser emission was applied [7]. Disadvantage of this approach consists in instability of the train frequency and the pulse amplitude. Also there is a requirement to suppress the reflection from the output end that complicates laser applications. Another approach consists in the application of a fiber saturable absorber within the laser cavity.Thus, Cr-doped fiber was used as absorber in Nddoped fiber [8]. In [9] it was demonstrated that a placing of Sm-doped fiber in the cavity of Yb-doped fiber laser allows one to get the pulse generation occurring in extremely stable manner with pulse energy of approximately 20 μJ. A Q-switch pulse had a nearly perfect pulse shape with a ∼ 650 ns FWHM. The interesting approach was applied in [10], where Bi-doped fiber played a role of the saturated absorber. In contrast to Cr and Sm-doped fibers, Bi