Removable optical tap for in-process characterization

Abstract

An integrated circuit includes optical waveguides defined in a semiconductor layer, and uses removable optical taps to allow for in-process characterization and trimming. These optical waveguides may be trimmed during fabrication of the integrated circuit to improve performance. Note that the trimming may modify indexes of refraction of portions of the optical waveguides or may involve a more invasive process. Moreover, the trimming may exclude or may not involve the use of a polymer and/or the carrier wavelengths at a given temperature may be stable as a function of time. The trimming process may use removable optical taps for external feedback to determine the amount of change required. These optical taps may be formed either in the semiconductor layer or the cladding layer, and they may be disabled with negligible impact to device performance via alterations to the cladding layer after the completion of trimming.