Direct bonding between laser wafers and magneto-optic waveguides

Wafer direct bonding is an attractive technique for the integration of different materials. In a previous study, the bonding between InP and several kinds of garnets which are essential to an optical isolator was demonstrated. When the optical isolator is integrated with the laser wafer as shown in Fig. 1, the surface of garnet wafer where a rib waveguide is formed is to be bonded with an etch stop layer for the vertical alignment. This paper reports the direct bonding between GaInAsP etch stop layer and Gd₃Ga₅O₁₂ (GGG) which is used as a substrate for magneto-optic crystal growth. The bonding is also described between InP and the garnet rib waveguide.