Sub-1 dB/cm submicrometer-scale amorphous silicon waveguide for backend on-chip optical interconnect

We demonstrate a submicrometer-scale hydrogenated amorphous silicon (a-Si: H) waveguide with a record low propagation loss of 0.60 +/- 0.02 dB/cm because of the very low infrared optical absorption of our low defect a-Si: H film, the optimized waveguide structure and the fabrication process. The waveguide has a core with a thickness of 440 nm and a width of 780 nm that underlies a 100-nm-thick ridge structure, and is fabricated by low-cost i-line stepper photolithography and with low-temperature processing at less than 350 degrees C, making it compatible with the backend process of complementary metal oxide semiconductor (CMOS) fabrication. (C) 2014 Optical Society of America