Efficient inter-chip optical coupling

A system, comprising an MCM, wherein the MCM includes:

• a first substrate having a first surface, wherein the first substrate includes:
• a first optical waveguide disposed on the first surface;
• and
• a first optical coupler optically coupled to the first optical waveguide, wherein the first optical coupler is configured to couple an optical signal between a plane of the first optical waveguide and a direction out of the plane of the first optical waveguide;
• a second substrate having a second surface facing the first surface of the first substrate, wherein the second substrate includes:
• a second optical waveguide disposed on the second surface;
• and
• a second optical coupler optically coupled to the second optical waveguide, wherein the second optical coupler is configured to couple the optical signal between a plane of the second optical waveguide and a direction out of the plane of the second optical waveguide;
• an optical interposer, positioned between the first surface and the second surface, configured to guide the optical signal between the first optical coupler and the second optical coupler, thereby reducing spatial expansion of the optical signal between the first optical coupler and the second optical coupler;
• a processor incorporated into one of the first substrate and the second substrate;
• and
• a memory incorporated into one of the first substrate and the second substrate.

A method for directly optically coupling an optical signal from a first substrate to a second substrate, the method comprising:

• transporting the optical signal in a first optical waveguide disposed on a first surface of the first substrate;
• optically coupling the optical signal out of a plane of the first optical waveguide using a first optical coupler disposed on the first surface;
• guiding the optical signal using an optical interposer which is positioned between the first substrate and the second substrate, thereby reducing spatial expansion of the optical signal;
• optically coupling the optical signal into a plane of a second optical waveguide using a second optical coupler disposed on a second surface of the second substrate;
• and
• transporting the optical signal in the second optical waveguide disposed on the second surface.