Micro-optical bench for alignment-free optical coupling.

We propose an optical coupling module, the micro-optical bench, designed for the purpose of completely passive alignment of optical components. The principle is for one to position a planar microlens array, semiconductor device submounts, and optical fibers by using reference planes and V grooves made on a Si substrate. A prototype was fabricated, and we achieved an optical coupling loss of less than 3 dB; small deviations among channels as low as 1 dB were achieved without any precise alignment. For multimode fibers, a coupling loss of approximately 0.5 dB was obtained.