Integrated Edge Coupler

An optical mode-size converter, extending between a first plane to a second plane along a first path, the optical mode-size converter comprising:

• a plurality of dielectric strips within a coupling layer arranged to receive a beam with a first optical mode incident on the first plane, wherein the plurality of dielectric strips are coupled to each other in a first evanescent coupling region;
• and
• a first waveguide within a functional layer disposed above or below the coupling layer, the waveguide supporting a second optical mode and traversing the second plane,
• wherein at least one of the plurality of dielectric strips is evanescently coupled to the first waveguide in a second evanescent coupling region,
• wherein the first optical mode has a larger mode size than the second optical mode,
• such that the converter is responsive to the first optical mode incident on the first plane to convert the first optical mode into the second optical mode in the first waveguide, along the first path towards the second plane, and
• wherein the first waveguide comprises a first layer and a second layer, and
• wherein an end of the second layer is closer to the first plane than an end of the first layer.