Abstract

Ytterbium (Yb³⁺) doped trigonal yttrium aluminum borate, Yb³⁺:YAl₃(BO₃)₄ (abbreviated Yb:YAB), represents a well-known structurally ordered laser crystal which is very suitable for the development of high-power lasers both in the continuous-wave and Q-switched regimes at ~1 μm [1]. It is an optically uniaxial (negative) crystal with non-centrosymmetric huntite-like structure (sp. gr. R32, point group 32) exhibiting high nonlinearity (d_eff > 1.4 pm/V [2]), being recognized as one of the most promising self-frequency doubling (SFD) laser crystals for generating coherent radiation in the visible spectral range [3]. The relatively broad and flat gain spectra of the Yb³⁺ ions in YAB support sub-100 fs pulse generation from passively mode-locked (ML) lasers [4, 5]. In combination with its relatively good thermal conductivity (4.7 Wm^-1K^-1 for 5.6 at% Yb doping [6]), as well as broad gain profiles, the Yb:YAB crystal has good potential for the power scalable operation of femtosecond lasers at ~1 μm [7]. In the present work, we report on a diode-pumped Yb:YAB laser delivering soliton pulses as short as 36 fs at 1059.7 nm with an average output power of 156 mW via Kerr-lens mode-locking (KLM).

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