Ge, B, P-doped silica glass films are widely used as optical waveguides because of their low losses and inherent compatibility with silica optical fibers. These films were etched by ICP ͑inductively coupled plasma͒ with chrome etch masks, which were patterned by reactive ion etching ͑RIE͒ using chlorine-based gases. In some cases, the etched surfaces of silica glass were very rough ͑root-mean square roughness greater than 100 nm͒ and we call this phenomenon plasma induced surface damage ͑PISD͒. Rough surface cannot be used as a platform for hybrid integration because of difficulty in alignment and bonding of active devices. PISD reduces the etch rate of glass and it is very difficult to remove residues on a rough surface. The objective of this study is to elucidate the mechanism of PISD formation. To achieve this goal, PISD formation during different etching conditions of chrome etch mask and silica glass was investigated. In most cases, PISD sources are formed on a glass surface after chrome etching, and metal compounds are identified in theses sources. Water rinse after chrome etching reduces the PISD, due to the water solubility of metal chlorides. PISD is decreased or even disappeared at high power and/or low pressure in glass etching, even if PISD sources were present on the glass surface before etching. In conclusion, PISD sources come from the chrome etching process, and polymer deposition on these sources during the silica etching cause the PISD sources to grow. In the area close to the PISD source there is a higher ion flux, which causes an increase in the etch rate, and results in the formation of a pit.

We present preparation of Ge nanostructures formed using by femtosecond laser pulse and origin of visible photoluminescence (PL) properties. High intensity of incident laser energy gives rise to make oxidized layer to surface of Ge nanoparticle after irradiation. Moreover, size dependent Raman shift and PL spectrums are observed with different fluences and various process surroundings. It is noted that the oxidation of Ge nanoparticle formed ambient surroundings plays an important role of photoluminescence.