%0 Journal Article %J Optics Express %D 2014 %T Focusing-curved subwavelength grating couplers for ultra-broadband silicon photonics optical interfaces %A Zhong, Qiuhang %A Veerasubramanian, Venkat %A Wang, Yun %A Shi, Wei %A Patel, David %A Ghosh, Samir %A Samani, Alireza %A Chrostowski, Lukas %A Bojko, Richard %A Plant, David %I OSA %K Gratings; Subwavelength structures %P 18224--18231 %U http://www.opticsexpress.org/abstract.cfm?URI=oe-22-15-18224 %V 22 %X We report on the design and characterization of focusing-curved subwavelength grating couplers for ultra-broadband silicon photonics optical interfaces. With implementation of waveguide dispersion engineered subwavelength structures, an ultra-wide 1-dB bandwidth of over 100 nm (largest reported to date) near 1550 nm is experimentally achieved for transverse-electric polarized light. By tapering the subwavelength structures, back reflection is effectively suppressed and grating coupling efficiency is increased to ?4.7 dB. A compact device footprint of 40 Ám x 20 Ám is realized by curving the gratings in a focusing scheme. %8 07/2014 %9 article