Integration of terraced laser diode and optical isolator by wafer direct bonding

Summary form only given. Wafer direct bonding is an attractive technique for integration of dissimilar materials without any adhesives. The authors have applied this technique to the bonding between III-V compound semiconductors and garnet crystals with the aim of integrating a laser diode and an optical isolator. In a previous study, we demonstrated the bonding between InP and several kind of garnets, the latter of which are essential to the optical isolator operating in the near infrared region. We study a laser diode integrated with an optical isolator. The isolator is contacted with the terraced laser diode by wafer bonding. The terraced laser diode requires a vertical mirror facet and a flat etched surface. A GaInAsP etch stop layer of the laser diode is prepared for the flat etched surface. A vertical alignment between an active layer of the laser diode and a guiding layer of the optical isolator can be achieved by adjusting the thickness of the cladding layers. We report the fabrication of the terraced laser diode and wafer bonding between the GaInAsP and the garnet crystals.