Growth, spectroscopy and lasing of the Yb-doped monoclinic Gd2SiO5 in the prospect of hydrogen laser cooling with Lyman-α radiation

We have grown good optical quality 10% Yb-doped Gd₂SiO₅ monocrystal by the Czochralski technique. The Yb segregation coefficient was measured to be 0.747. In agreement with the monoclinic symmetry of the host, the Yb fluorescence extrema were found to deviate from the N_m and N_g principal axes and a fourth spectroscopic parameter representing the rotation of the fluorescence distribution was introduced for a full description. Diode pumped laser operation at Brewster incidence was demonstrated to be significantly more efficient if the lasing propagation corresponds to the maximum fluorescence inside the crystal. We obtained a laser emission tunable between 1079 and 1100 nm, showing that our crystal is the best choice for the application to the production of QCW Lyman-α radiation by resonant four-wave-mixing in mercury vapor.