Vertically-coupled grating coupler based on binary blazed sub-wavelength grating and preparation method thereof

The invention discloses a vertically-coupled grating coupler based on a binary blazed sub-wavelength grating. The vertically-coupled grating coupler comprises a functional layer, a bonding layer and a substrate layer from top to bottom. The functional layer is of a ridge-shaped structure and comprises an input/output light coupler and a photonic waveguide device area. The input optical coupler and the output optical coupler are symmetrically arranged, binary sub-wavelength blazed grating arrays are periodically arranged in the input optical coupler and the output optical coupler, a primary sub-wavelength grating and a secondary sub-wavelength grating which are different in width are arranged in each period, and interval grooves different in width are formed between the adjacent sub-wavelength gratings. And the last secondary sub-wavelength grating is close to the middle optical waveguide area. According to the invention, the grating coupler based on the binary blazed sub-wavelength grating is optimally design