Low-Cost Optical Subassembly Using VCSEL Pre-Self-Aligned With Optical Fiber for Optical Interconnect Applications

We propose a self-alignment process of an optical device with an optical multimode fiber (MMF) and a novel optical subassembly using a pre-self-aligned device. In order to form the pre-self-aligned device, the optical device such as a vertical-cavity surface-emitting laser (VCSEL) is aligned with the MMF using the surface tension of a transparent liquid adhesive. The optical subassembly we have developed is provided with a simple structure consisting of the pre-self-aligned VCSEL and an interposer board to be mounted on a printed circuit board (PCB). Details of the low-cost self-alignment technology and the optical subassembly are reported. Alignment accuracy of average 13 ??m is achieved and coupling efficiency of the self-aligned VCSEL to the MMF is determined to be maximum 35%. 1-Gb/s optical signal transmission using the optical subassembly is also demonstrated. This self-alignment technology and the fabricated optical subassembly are effective in achieving low-cost optical modules for optical interconnect systems from commodities to high-end applications.