Characterizing Integrated Photonics Devices

A method for characterizing a photonic device in a photonic layer of an integrated circuit, comprising:

• coupling an optical wave into a first optical coupler in the photonic layer;
• providing an output signal from the photonic device in response to the photonic device receiving a first portion of the optical wave;
• providing a second portion of the optical wave from the first optical coupler, wherein the second portion of the optical wave was not coupled into the photonic device;
• and
• characterizing at least one of an optical transmission characteristic or an optical reflection characteristic of the photonic device based at least in part on the second portion of the optical wave and the output signal.

An integrated circuit, comprising:

• at least one photonic layer that includes one or more optical waveguides;
• a first grating coupler that couples at least a first optical mode outside of the photonic layer to a first waveguide in the photonic layer;
• a photonic device that includes one or more ports in the photonic layer;
• a first optical splitter that includes three or more ports in the photonic layer, including
• a first port optically coupled to the first grating coupler,
• a second port optically coupled to a first port of the photonic device, and
• a third port optically coupled to a first Sagnac loop reflector.