Semiconductor devices of optical neural network and methods of forming the same

An apparatus for implementing an artificial neural network, comprising:

• an input region configured to receive a first optical signal;
• a neural network region optically coupled to the input region and configured to transform the first optical signal to a second optical signal;
• and
• an output region optically coupled to the neural network region and configured to convert the second optical signal into a first electrical signal;
• wherein the neural network region comprises a plurality of waveguides that are disposed across a plurality of vertically stacked insulator layers, respectively.

A method for making semiconductor devices, comprising:

• forming a plurality of optical devices in an overlaying silicon layer disposed on a first side of a silicon-on-insulator (SOI) substrate;
• forming, over the plurality of optical devices, a plurality of first waveguides disposed across a plurality of first insulator layers, respectively;
• and
• forming, over a second side of the SOI substrate opposite to the first side, a plurality of second waveguides disposed across a plurality of second insulator layers, respectively;
• wherein the plurality of first waveguides and the plurality of second waveguides collectively form a plurality of photonic neural network layers of an artificial neural network.