Sub-100 fs mode-locked laser operation of new disordered Yb : KInY(WO4)2 crystal

Abstract

In this contribution we report what it is, to the best of our knowledge, the first femtosecond mode-locked laser operation of In-modified KY(WO4)2 crystals doped with Yb3+. The presence of indium, co-substituting yttrium position, introduces disorder in the crystal structure. KLn(WO4)2 monoclinic crystals, with Ln = Y, Gd or Lu, are well established laser crystals characterized by very large absorption and emission cross sections in the Nm crystal direction [1]. In particular, the laser properties of Yb-doped KY(WO4)2 crystal have been object of study in the past [2-4]. In this crystal, Yb3+ sits a single position and the main origin of its band broadening is the interaction with the vibrating lattice environment. Due to the small ionic radius of In3+ replacing the larger Y3+ cation, disorder is introduced in the crystal structure. This disorder induces inhomogeneous broadening of the Yb3+ optical bands and therefore allows to produce ultrashort laser pulses.