2.8 μm passively Q-switched Er:CaF2 diode-pumped laser

A mid-infrared Er doped CaF2 crystal was successfully grown by the bridgeman method. Efficiently continuous wave and Q-switched laser operations were demonstrated at 2.8 mu m with a 4 at.% Er doped CaF2 crystal end-pumped by a fiber-coupled 974 nm diode laser. The continuous wave output power of 295 mW was obtained in a compact linear cavity. A stable 2.8 mu m passively Q-switched Er:CaF2 laser was also demonstrated with a graphene saturable absorber. Under an absorbed pump power of 2.353 W, an average output power of 172 mW was generated with a pulse duration of 1.324 mu s and a repetition rate of 62.70 kHz, corresponding to the single pulse energy of 2.74 mu J and the peak power of 2.07 W, respectively. The high-quality Er:CaF2 crystal and the monolayer graphene are an ideal combination to directly obtain a near 3 mu m mid-infrared region pulse laser. (C) 2016 Optical Society of America