Multilayer waveguide grating coupler

A photonics chip with a multilayer waveguide grating coupler, the photonic chip comprising:

• a signal source configured to generate an input light;
• and
• a multilayer waveguide grating coupler in optical communication with the signal source to receive the input light, the multilayer waveguide grating coupler including,
• at least one first grating having a plurality of first copropagating waveguides, each first copropagating waveguide having a first periodically modulated width;
• and
• at least one second grating having a plurality of second copropagating waveguides positioned a grating spaced distance from the first grating, each second copropagating waveguide having a second periodically modulated width, the second grating positioned so that a phase offset is present between the first periodically modulated width of the first copropagating waveguides and the second periodically modulated width of the second copropagating waveguides, the grating spaced distance and the phase offset being selected so that light diffracted in a first direction from the first copropagating waveguides and the second copropagating waveguides interferes constructively to form a first light beam and light diffracted in a second direction from the first copropagating waveguides and the second copropagating waveguides interferes destructively.

A method of forming a multilayer waveguide grating coupler, the method comprising:

• depositing a first layer of core material on a first layer of cladding material;
• forming a first grating having a plurality of copropagating first waveguides from the first core material, each first waveguide of the plurality of copropagating first waveguides having a first periodic modulation of a width of the first waveguide;
• depositing a second layer of cladding material of a select thickness over the first grating;
• depositing a second layer of core material over the second layer of cladding material;
• and
• forming a second grating having a plurality of copropagating second waveguides from the second layer of core material, each second waveguide of the plurality of copropagating second waveguides having a second periodic modulation of a width of the second waveguide, the formed second grating positioned to create a select phase offset between the first periodic modulations of the width of the first waveguides and the second periodic modulations of the width of the second waveguides.