Nd:YVO4 and YVO4 laser crystals integration by a direct bonding technique

Laser crystal integration using a neodymium-doped yttrium vanadate (or orthovanadate) laser crystal, and non-doped yttrium vanadate crystals that function as cold fingers has been demonstrated. In our bonding technique Of YVO4 crystals, a newly developed dry etching process was adopted in the preparation for contact of mechanically polished surfaces. In the successive heat treatment process, temperature optimization was essential to get rid of precipitation of vanadic acid caused by the thermo-chemical reaction in a vacuum furnace. The bonded surface of 5 nun x 6 mm was studied via optical characteristics and magnified inspection. In addition, we also compared the integrated crystal with a normal one in laser output power pumped by a CW laser diode. From these experiments, it was clear that the integrated Nd:YVO4 laser crystal, securing the well-improved thermal conductivity, can increase laser output power nearly twice that of the conventional single crystal which was cracked in high power laser pumping due to its intrinsic poor thermal conductivity.