Waveguides, beam splitters, filters, and routers are implemented in photonic crystals.

Several analog-to-digital converter (ADC) devices and part of a multispectral receiver have been designed, fabricated, and tested to demonstrate their feasibility as part of an effort to establish the organizational and technological foundation for development of photonic-crystal-based devices for commercial and military applications. Also known as photonic-band-gap devices, photonic crystals contain periodic structures having feature sizes in the submicron range — less than the wavelengths of light that the devices are intended to handle. Photonic crystals can be fabricated by techniques used in the integrated-circuit and microelectromechanical systems (MEMS) industries.

The periodic structures can be tailored to manipulate and control light in a wide variety of ways. In an important class of contemplated applications, photonic crystals of predominantly two-dimensional character would be used for in-plane distribution and routing of optical signals, while photonic crystals of three-dimensional character would be used for out-of-plane distribution and routing of optical signals. In both the two- and three-dimensional cases, the photonic crystals would make it possible to provide high-density optical interconnections among multiple photonic and/or optoelectronic circuits oriented at various angles to the photonic crystals.