A new amorphous silicon application related to the patterning of refractive index for the purpose of defining and integrating photonic-device elements is emerging. Photonic device elements include waveguides, splitters, mirrors, optical memories, etc. Hot-wire-deposited amorphous silicon has several attributes that make it an exceedingly attractive matrix for photonic device patterning, including: high hydrogen solubility limits; relatively little sub-gap absorption; low stress; non-peeling films; and fast, economical deposition of thick (greater than or equal to5 mum) films, as well as optically smooth as-deposited surfaces, even on thick films. The growing catalog of proposed and/or demonstrated amorphous silicon-based optical devices is rapidly expanding.