Efficient Femtosecond Mode-Locked Nd,Y:Srf2 Laser

An efficient femtosecond mode-locked laser using Nd and Y-codoped SrF2 crystal as the gain medium is presented in this letter. A 332 fs pulse centered at 1057 nm with a repetition rate of 89.8 MHz, a spectral width of 4.3 nm, and a mode-locked output power of up to 395 mW has been obtained under 1 W pump power, corresponding to an optical-to-optical efficiency of 39.5% and a slope efficiency of 69%. To the best of our knowledge, this is the highest optical efficiency in femtosecond Nd-doped crystal lasers.