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Magneto-optical phase shift is effective to realize on-chip optical isolators. Optical isolators are fabricated on SOI platforms with isolation ratios of 30 and 16 dB for TM and TE mode input, respectively.

Magneto-optical isolators exhibit performance characteristics of a 30 dB isolation, a 20-dB isolation bandwidth of 8 nm, and a temperature-insensitive isolation. The magneto-optical switch is successfully demonstrated with a latching function. © 2020 The Author(s)

Wafer direct bonding is an attractive technique for the integration of different materials without any adhesives. The authors have applied this technique to bonding of a III-V compound semiconductor and a garnet crystal for the aim of integrating a laser diode and an optical isolator. In a previous study, we demonstrated the bonding between InP and several kinds of garnets [1], the latter of which are essential to an optical isolator. Figure 1 shows a laser diode integrated with an optical isolator by wafer direct bonding. A GaInAsP etch stop layer of the laser diode is prepared for vertical alignment between an active layer of the laser diode and a guiding layer of the optical isolator. The vertical alignment can be achieved by adjusting the thickness of cladding layers. The lateral alignment of a waveguide with the laser stripe can be accomplished by conventional lithography and etching techniques. In this paper, we report the direct bonding between GaInAsP and Gd3Ga5O12 (GGG). GGG is used as a substrate for epitaxial growth of magnetic garnets.

Wafer direct bonding is an attractive technique for the integration of different materials The authors have applied this technique to the bonding between III-V compound semiconductors and magneto-optic crystals with the aim of the integration of a laser diode and an optical isolator because it overcomes the issues associated with the lattice mismatch between the two different materials [1,2]. In a previous study, we demonstrated the bonding between InP and several kinds of garnets [3] which are essential to an optical isolator. 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. In this paper, we report the direct bonding between GalnAsP 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.

The all optical ATM is an attractive transmission method of information that realizes B-ISDN in the future. The speed of information signal processing in all optical scheme is higher compared with the electrical control. In order to realize the all optical ATM,it is required to establish the method for recognizing address in an all-optical manner.

Nonlinear optical devices have been studied for their possible uses in various all-optical functions. The optical bistable devices, which employ intensity-dependent refractive index change, have been demonstrated in a GaAs—GaAlAs superlattice etalon1 and in a CdS x Se1- x doped glass etalon.2 A pioneering work on its waveguide version was also reported for the Fabry-Perot resonator constructed with a GaAs/GaAlAs MQW waveguide.3 In order to integrate the bistable device with other optical functional devices, it is essential to use distributed Bragg reflectors for optical feedback.