High-performance silicon nitride focusing grating couplers with AlCu/TiN reflectors for a visible wavelength (660 nm) have been designed and fabricated in a standard complementary metal-oxide-semiconductor pilot line. The influence of the bottom oxide cladding thickness on the grating decay length and efficiency is theoretically and experimentally investigated. It is shown how the metal reflector not only increases the efficiency but also allows reduction of the radiated beam size. Coupling efficiencies above 59% have been measured for compact focusing gratings.
© 2013 Optical Society of America
Diffraction and Gratings
Original Manuscript: June 7, 2013
Revised Manuscript: June 15, 2013
Manuscript Accepted: June 15, 2013
Published: July 10, 2013
Sebastian Romero-García, Florian Merget, Frank Zhong, Hod Finkelstein, and Jeremy Witzens, "Visible wavelength silicon nitride focusing grating coupler with AlCu/TiN reflector," Opt. Lett. 38, 2521-2523 (2013)