US Patent 11422303 Waveguide with attenuator

The present disclosure relates to semiconductor structures and, more particularly, to a waveguide structure with attenuator and methods of manufacture. The structure includes: a waveguide structure including semiconductor material; an attenuator underneath the waveguide structure; an airgap structure vertically aligned with and underneath the waveguide structure and the attenuator; and shallow trench isolation structures on sides of the waveguide structure and merging with the airgap structure.