First experimental demonstration of high-directionality fiber-chip grating coupler with interleaved trenches

We present the first experimental demonstration of a new fiber-chip grating coupler concept that exploits the blazing effect by interleaving deep and shallow etch trenches to maximize directionality. The grating couplers were fabricated using both 193 nm deep-ultraviolet lithography and electron beam lithography. The measured peak fiber-chip coupling efficiency is -1.8 dB at a wavelength of 1550 nm, with a 3 dB bandwidth of 52 nm.