Abstract: Disclosed herein are integrated photonics assemblies, circuits, systems and methods therefor. The systems can include a first integrated photonics assembly having a first functionality, in which the first assembly includes a plurality of modular photonic integrated subcircuits. Each subcircuit can be pre-fabricated and can be configured to transfer light to and receive light from another subcircuit based on the first functionality. An output port of a first subset of the subcircuits can be configured to be aligned with an input port of a second subset of the subcircuits. At least one subcircuit can be configured to be removed from the first integrated photonics assembly and connected to a second integrated photonics assembly having a second functionality. The first integrated photonics assembly can be different from the second integrated photonics assembly and the first functionality can be different from the second functionality.