Comparison of evanescent and directly coupled optical interconnections embedded into electronic interconnection substrates

Summary form only given. Fabrication process technology and measurement results for two different embedded detector structures are described: thin film InGaAs photodetectors embedded in a polymer waveguide and below a polymer waveguide, with both exhibiting efficient coupling. To create the embedded detector waveguide structures, thin film photodetectors are fabricated through substrate removal, bonded to a SiO₂-coated Si substrate, and a polymer waveguide is subsequently deposited onto the photodetector and patterned into a channel. The theoretical coupling efficiency was calculated based using the bi-directional beam propagation method (BPM). The calculated coupling efficiency was 60.2% for direct coupling (BCB) and 59.3% for evanescent field coupling (ULTEM/BCB).