Amorphous silicon waveguides and light modulators for integrated photonics realized by low-temperature plasma-enhanced chemical-vapor deposition.

A new amorphous silicon waveguide is realized by use of amorphous silicon carbon as cladding material. The structure is characterized both experimentally and theoretically, and its application for optical interconnections in photonic integrated circuits on silicon motherboards is proposed. The fabrication process is based on low-temperature (220 degrees C) plasma-enhanced chemical-vapor deposition and is compatible with standard microelectronic processes. Propagation losses of 1.8 dB/cm have been measured at the fiber-optic wavelength of 1.3 microm. A strong thermo-optic coefficient has been measured in this material at this wavelength and exploited for the realization of a light-intensity modulator based on a Fabry-Perot interferometer that is tunable by temperature.

Absorptance enhancement for laser metal processing: application to steel samples.

We describe a reliable technique that noticeably increases the absorptance of a metal surface without any change in its chemical and physical properties, obtained through a chemically induced enhancement of the surface roughness. The main advantages of this method are low cost, easy handling, and low tolerances. A set of optical and mechanical measurements was performed to gain a detailed knowledge of the technique.