When optical components are reduced to the nanoscale, they exhibit interesting properties that can be harnessed to create new devices. For example, imagine a block of material with thin layers of alternating materials. This creates a periodic arrangement of alternating dielectric constants, forming a "photonic crystal" that is analogous to the electronic crystals used in semiconductor devices. Photonic crystals, along with quantum dots and other devices patterned at the nanoscale, may form the basis for sensors and switches used in computers and telecommunications. More information on Nanophotonics can be found here.