Large-core (1,000㎛×1,000㎛) multimode optical waveguide devices are fabricated by a rubber-molding process. The master is patterned by using Su-8 thick-photoresist developed for micro electromechanical systems (MEMS) fabrication. The rubber mold of the pattern is fabricated with a PDMS elastomer. The PDMS mold is used to replicate the waveguide pattern of NOA72, UV-curable epoxy. The propagation loss of the waveguides is about 0.5 dB/cm at the wavelength of 650 nm. Based on these waveguides, two types of the power splitter have been fabricated; one is T-shaped and the other Y-shaped. The T-shaped splitter has a structural excess loss of 1.5 dB and its split ratio is 1 : 0.96. The Y-shaped splitter has a structural excess loss of 0.3 dB and its split ratio is 1 : 1.04.
