We present an overview of our work on the design and fabrication of micro/nano-scale photonic circuits and
networks on what we call "optical printed circuit boards" (O-PCBs) and "VLSI photonic integrated circuit
chips"(VLSI-PICs) of generic and application-specific nature. The O-PCBs and photonic chips consist of
2-dimensional planar arrays of optical wires, circuits, and networks of micro/nano-scale to perform the functions
of sensing, storing, transporting, processing, switching, routing, and distributing optical signals on flat
boards or chips. We describe and discuss scientific and technological issues concerning the miniaturization,
interconnection and integration of micro/nano-scale photonic devices, circuits, and networks leading to small
and very large scale integration in terms of photonic scaling rules and discuss their use for the design and fabrication
of the photonic integrated circuits and networks. Design rules for the miniaturization and integration of
the micro/nano-photonic systems are discussed in comparison with those of the micro/nano-electronic systems.
Materials include polymer/organic materials and silicon materials. Structural bases include photonic crystals,
ring resonators, and plasmonic structures. Compatibility issues between diverse materials and devices are
discussed especially in regard to applications. Recent progresses and examples are presented.