CMOS compatible ALD high-k double slot grating couplers for on-chip optical interconnects

Silicon-on-insulator(SOI) novel on-chip grating couplers for double slot high-k waveguides are experimentally demonstrated. The devices were fabricated with standard CMOS process technology. The grating couplers were designed for the best performance at the C-band communication range. Two thin layers of aluminum oxide formed the slot region of the waveguide. The high-k layers were deposited using the atomic layer deposition (ALD) method. A reliable process was realized by etching the structures to the buried oxide. Effect of the top oxide cladding layer on the efficiency was studied. The grating couplers had a measured efficiency of 22% at 1.55μm wavelength. This efficiency is competitive to other results reported by other groups.