Transform-Limited Ultrashort Pulse Generation by χ(2)-Lens Mode-Locking of Nd:LuYAG Laser with Inhomogeneously Broadened Gain Bandwidth

In recent years, diode-pumped solid-state lasers based on Nd-doped crystals with disordered structure have attracted significant attention. The inhomogeneous broadened fluorescence spectrum of these crystals allows generation of pulses with sub-picosecond duration using traditionally narrow gain bandwidth transitions of the Nd3+ ions [1]. However, the main drawback is the lower thermal conductivity of disordered crystals in comparison with that of Nd:YAG, which limits the laser output power and efficiency. Nowadays, relatively good thermal and laser properties have been demonstrated using Nd-doped mixed aluminium garnets Nd:LuxY3-xAl5O12 (Nd:LuYAG), Nd:GdxY3-xAl5O12 (Nd:GdYAG) and Nd:GdxLu3-xAl5O12 (Nd:GdLuAG) and continuous-wave laser operation with high efficiency and output power of several watts are achieved [2]. More recently, a Nd:Lu1.5Y1.5Al5O12 laser has been mode-locked using SESAM with output power of 850 mW and pulse duration of 6.6 ps [3]. However, the pulses have been chirped, i.e. the obtained pulse duration is not transform-limited.