Photonic chip with edge coupler and method of manufacture

A method of manufacturing a photonic chip, the method comprising:

• providing cladding material;
• forming an edge coupler, comprising depositing a composite guiding structure comprising a plurality of substantially parallel planar layers of optical guiding material, wherein forming the edge coupler comprises:
• removing a portion of the cladding material at a first end of the cladding material along a first axis to form a cladding material surface;
• fabricating a planar layer of optical guiding material on the cladding material surface;
• depositing a cladding material onto the layer of optical guiding material to form a new cladding material surface;
• and
• repeating the fabricating a planar layer of optical guiding material and the depositing a cladding material onto the layer of optical guiding material to form a composite guiding structure comprising a plurality of substantially parallel planar layers of optical guiding material interleaved with cladding material;
• and
• wherein:
• each layer of the composite guiding structure extends into the cladding material,
• each layer is aligned at a first edge of the photonic chip, and
• the layers overlap along a first axis which is perpendicular to a plane of the planar layers of optical guiding material;
• and
• forming a surface of the photonic chip for deposition of a waveguide on the cladding material, the waveguide being arranged to at least partially overlap along the first axis with a layer of the composite guiding structure.