Silicon Wafer: A Direct Output Coupler In Tm: Ylf Laser

We present a high power diode-pumped continuous-wave Tm: YLF (Tm3+-doped lithium yttrium fluoride) laser with a piece of silicon wafer as the output coupler (Si-OC laser) directly. Under the pump power of 40 Wat 793 nm, a maximum output power of 12.1 W is obtained with a beam quality of M-2 <= 1.55 at 1887 nm, corresponding to an optical-to-optical efficiency of 30.25% and a slope efficiency of 33.21%. To the best of our knowledge, this is the first report on directly utilizing silicon as an output coupler (Si-OC) in the solid Tm: YLF laser system. Due to the intriguing characteristics of silicon, such as negligible absorption in the wavelength region around 2 mu m, high damage threshold, low cost and long-pass filter properties, double-side polished monocrystalline silicon wafer is considered as an outstanding candidate output coupler in the high-power laser system 2 mu m spectral region, which may dramatically reduce the total manufacturing costs of the 2 mu m laser system.