Abstract

Recently, diode-pumped solid-state lasers based on disordered Nd-doped crystals have attracted significant attention. In mode-locked operation they have a potential to generate tunable laser radiation with pulse duration in sub-picosecond time scale as well as to emit muti-wavelength ultrashort pulses which makes them attractive as a source for terahertz generation [1]. Nowadays, the binary and ternary inorganic silicate crystals Y₂SiO₅ (YSO), Lu₂SiO₅ (LSO) and LuYSiO₅ (LYSO), doped with different rare ions including Nd³⁺ and Yb³⁺, are in the focus on intensive research as inhomogeneously broaden laser media. A dual-wavelength mode-locked laser based on Nd: LYSO crystal is demonstrated [2]. By substituting part of yttrium ions with scandium ions, a novel laser crystal Nd:Sc_0.2Y_0.8SiO₅ (Nd:SYSO) was grown with Czochralski method along the crystallographic b axis by Shanghai Institute of Ceramics. The Nd:SYSO single crystal with multi-crystallographic sites and birefringence property is with the same structure as monoclinic Nd:YSO. The strong natural birefringence of monoclinical biaxial crystals overwhelms the thermally induced birefringence, which is the source of thermal depolarization observed in isotropic media. The presence of multi-type substitutional sites in this crystal provides strong inhomogeneous field for rare earth dopants, which induces large ground-state split and broadened optical spectra. Hence, three-wavelength operation in CW and Q-switched Nd:SYSO laser is demonstrated [3]. However mode-locking operation of Nd:SYSO laser is still a challenge.

© 2013 IEEE