Laser action in Yb3+:YCOB (Yb3+:YCa4O(BO3)3)

Progress in the growth of the rare earth calcium oxyborate crystals has now generated a new class of laser materials that can be used as both a laser host and a nonlinear frequency converter. Laser action and self-frequency doubling (SFD) has been observed with both 10% and 20% Yb3+-doped YCOB crystals. Laser operation was obtained in a hemispherical linear cavity, end-pumped with a tunable cw Ti:Sapphire or a 980 nm laser diode pump source. Under Ti:Sapphire pumping at 900 nm, an output power of 230 mW and a slope efficiency of 29% was obtained using the 10% doped sample. Laser action was seen at 1050 nm, Laser operation of the 20% sample had a maximum output power of similar to 300 mW with a slope efficiency of 35.8% at 1088 nm Laser action was not obtained at the peak of the fluorescence emission (similar to 1030 nm) in this crystal as a consequence of self-absorption on the short-wavelength side of the emission band. Diode-pumped operation at the narrow absorption peak of 977 nm was achieved and early results show an improved slope efficiency of 34% in comparison to the 10% doped crystal under Ti:Sapphire pumping, We have also observed self-frequency doubling in Yb3+:YCOB. The 20% Yb3+:YCOB crystal used for this test was cut with a phase-matching angle of 36.22 degrees. The self-frequency doubling efficiency was low due to the absence of any frequency selective elements in the cavity to narrow the linewidth of the fundamental emission, The SFD emission occurred at 543 nm.