Feasibility study of a direct bonding method for laser crystals; Evaluations of YVO yttrium orthovanadate bonded laser crystals

Sugiyama, Akira; Nara, Yasunaga

We succeeded in fabrication of an integrated laser crystal with good heat conductivity by bonding two kinds of crystals; one is neodymium-doped YVO crystal (Nd: YVO) which is used for high peak power lasers and another is its host crystal YVO. Instead of conventional chemical etching, dry etching technique using an argon ion beam has been newly developed for the bonding of these crystals. It is essential for the heat treatment of this bonding to optimize the processing temperature for preventing vanadic acid precipitation due to thermo-chemical reaction. Optical characteristics of the bonded crystals were investigated. Bonded interface of the crystal was also observed with a transmission electron microscope (TEM). Through this experimental study, we made it clear that thermal conductivity of the integrated Nd: YVO/YVO crystal is much improved and the crystal possesses good lasing capability of increasing laser output without destruction of crystals due to thermal stress.