Low-loss thermally stable waveguide with 45° micromirrors fabricated by soft molding for fully embedded board-level optical interconnects

Abstract

A high performance polymer waveguide array with 45° micromirrors was fabricated by soft molding to achieve fully embedded board-level optoelectronic interconnects. One-step-transferring of a 3-D polymer structure is demonstrated. Low-loss and thermally stable UV curable polymers based on fluorinated acrylate are chosen as waveguide core and cladding materials. A 45° total interior reflection (TIR) micromirror was formed by two methods: blade cutting and mechanical polishing. And the surface roughnesses are further improved by using a focused ion beam (FIB) technique. The high-quality 45° micromirror was obtained to provide surface-normal light coupling between waveguide and the optoelectronic devices. The measured propagation loss of the multimode waveguide was 0.156dB/cm at 850nm wavelength. The excess loss of the mirror was less than 1.5dB.