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Single-Mode Optical Coupling Technology Using Movable Micro-Mirror Array and Surface-Emitting DFB Laser Array for High-Density 3-D Integration

Technologies for high-density integration of optical and electrical components are indispensable for next-generation optical transceivers whose capacity will exceed 400 Gbps. 3-D vertical integration technology with high optical coupling efficiency between a single mode fiber (SMF) array and lens-integrated surface emitting laser (LISEL) array using micro electro mechanical system (MEMS)-based movable micro-mirrors can meet this requirement. Light emitted from the LISEL is reflected at the micro-mirror and coupled to the SMF. Since the micro-mirror can steer the beam emitted from the LISEL to the SMF, the coupling efficiency that depends on the alignment accuracy between the LISEL and SMF is adjustable. After the alignment is completed, the position of the micro-mirror is fixed to keep high coupling efficiency. An optical sub-assembly (OSA) incorporating the LISEL, micro-mirror, and SMF array was fabricated using surface mount technology. All optical components were passively aligned, and the positions of micro-mirrors were adjusted to make a precise optical coupling to the SMFs as a post alignment. To confirm the effectiveness of this post-alignment system, the characteristics of the optical coupling to the SMF array were measured. It was found that the position of the reflected beam could be controlled to sub-micro-meter accuracy.