Fully vertical-coupling and one-step etching subwavelength binary blazed grating coupler

摘要

We proposed a fully vertical-coupling and one-step etching subwavelength binary blazed grating (BBG) coupler with coupling efficiencies exceeding 80% at a wavelength of 1.55μm. Based on reflector grating and Bragg bottom reflector layer, the coupling efficiency gets its maximum 90% when λ is equal to 1.535μm with the 1 dB wavelength bandwidth is around 35nm. The BBG is formed with multiple rectangular pillars having different widths and uniform height, which is a kind of binary version of the triangular tooth shape of the blazed grating and can be easily fabricated by only one etching step. It is CMOS compatible and available for mass production.