45 $^{\circ}$ -Mirror Terminated Polymer Waveguides on Silicon Substrates

The 45°-mirror terminated polymer waveguides fabricated on a silicon substrate are demonstrated for on-chip out-of-plane optical interconnects. The silicon 45^° microreflectors are fabricated on an orientation-defined (100) silicon substrate by using anisotropic chemical wet etching. On using a photolithography process, we observe two vertically bending paths at the input and output ports of polymer waveguide on a silicon substrate with 45^° microreflectors. The transmission efficiency of -3.77 dB is measured for a 0.5-cm polymer waveguide combined with the 45^° microreflectors. The optical loss occurring at the 45^°-mirror is -0.27 dB. The channel-to-channel crosstalk for the 250-μm pitch is less than -40 dB. The wider alignment tolerance up to ±15 μm would facilitate the active-device assembly on a silicon substrate.