Optical waveguide adapter assembly

An optical waveguide adapter assembly comprising:

• a solid core optical waveguide extending between a free end and a coupled end and having a solid waveguiding core with an associated first optical mode field size;
• a hollow core optical waveguide extending between a free end and a coupled end and having a hollow waveguiding core with an associated second optical mode field size;
• and
• an optical mode field adapter extending between a first end and a second end and having a waveguiding core having a shape, a refractive index property, or a combination thereof that changes an optical mode field of a waveguided optical signal substantially between the first optical mode field size at the first end of the optical mode field adapter and the second optical mode field size at the second end of the optical mode field adapter, wherein:
• the first end of the optical mode field adapter is joined to the coupled end of the solid core optical waveguide to provide optical coupling between the waveguiding core of the solid core optical waveguide and the waveguiding core of the optical mode field adapter, and
• the second end of the optical mode field adapter is joined to the coupled end of the hollow core optical waveguide to provide optical coupling between the waveguiding core of the hollow core optical waveguide and the waveguiding core of the optical mode field adapter.