Stacked polymeric multimode waveguide arrays for two-dimensional optical interconnects

Two-dimensional (2-D) polymeric multimode waveguide arrays with two reflection-mirrors have been fabricated for optical interconnects between 2-D arrayed vertical-cavity surface-emitting lasers and detectors. Contact printing lithography was adopted for simple and low-cost process using ultraviolet-curable epoxy-based polymers. Fabricated waveguides were diced of the same size and stacked one by one with lateral positional errors less than ±20 μm. Two kinds of mirrors were fabricated: single-reflection mirror and double-reflection mirror. Double-reflected mirrors resulted in lower losses with 1.2 dB than single reflected mirrors with 2.1 dB. The average insertion losses of 16-channel arrayed waveguides with two single-reflection mirrors and with two double-reflection-mirrors were measured to be 6.1 and 4.4 dB for 6-cm-long waveguides at a wavelength of 830 nm, respectively. The crosstalk between the waveguides was less than -25 dB. The characteristics of the waveguide arrays are good enough for applications to optical interconnects.