Passively Mode-locked Diode-pumped Yb

Ultrafast (UF) mode-locked (ML) lasers are extremely powerful tools in scientific research and industrial applications including material processing nonlinear optics attosecond science metrology etc. The most popular UF Ti:sapphire laser applications are limited by its high ownership cost system complexity and low power transfer efficiency. Yb3+:CaF2 has been recognized as a promising candidate for a high efficient and high power femtosecond laser for its simple energy-level scheme high quantum efficiency (~1) very small quantum defect (<10%) long upper-state lifetime (2.4 ms) broad emission spectrum (>70 nm) high thermal conductivity and compatibility with high power InGaAs diode pumping. Two types of Yb3+:CaF2 ML resonators based on semiconductor saturable absorber mirrors (SESAM's) and Kerr lens mode-locking (KLM) have been demonstrated and analyzed in detail. A Kerr-lens ML oscillator was constructed for continuous-wave modelocking operations by incorporating an additional optical element with an enhanced nonlinear Kerr coefficient which represents the first such investigation for an Yb3+:CaF2 oscillator to our best knowledge.