Abstract

Q-switched fiber lasers have found a number of applications such as medical treatment, micromachining, diagnostics and others. All-fiber pulsed lasers are of special interest since exhibiting all advantages of fiber lasers, namely compactness, absence of mechanical elements, long time stability etc. One of the promising ways to build such pulsed laser scheme consists in the application of a fiber saturable absorber. Thus, in [ 1 ] 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 with energy of approximately 20 pJ and time duration of 650 ns. Another approach was applied in [2], where Bi-doped fiber played a role of the saturated absorber. It is known that Tm-ions exhibit absorption band near 1.58 -m where Er-doped fiber lasers operate. In [3] this fact was used to create Q-switched Er-laser with Tm-doped fiber as a saturable absorber. However laser scheme exploited the core pumped configuration, as result the pulse energy was as small as 9 -J. Pulse duration was measured as 420 ns. To increase the pulse energy in this paper we use cladding pumped Er-doped fiber. Also, to reduce pulse duration we have used heavily Tm-doped fiber with a high concentration of the ion pairs. In this case the relaxation time is determined by the ions interaction within the pair.

© 2011 Optical Society of America