Bruno Sfez

Etching of photosensitive chalcogenide glasses:experiments and simulations.

We have developed a three-dimensional simulation algorithm based on fast marching method that mimics the etching behavior of chalcogenide photoresists, especially for maskless interference lithography. This lithography exposure is characterized by continuous variation of the exposure intensity inside the photoresist, without step like variation. Furthermore, the chalcogenide photoresist has a gray-scale behavior, without definite threshold. The resulting etching process is very sensitive to exposure dose and etching time. The optimal relations between these parameters are determined both theoretically and experimentally. A very good agreement between calculation and experimental results is shown, opening the door to complex nanostructures engineering.

Fabrication and Characterization of Thermally Evaporated Omnidirectional Mirrors

Omnidirectional mirrors based on chalcogenide and cryolite were fabricated by thermal evaporation. These mirrors are characterized using a two-dimensional mapping that provides a direct, visual signature. These signatures are presented for different multilayer structures. A mirror with an omnidirectional reflectivity of more than 94% and with a transverse electric omnidirectional reflectivity of more than 99.99% for high-incident angles is demonstrated. A surface roughness of less than 5 nm was obtained.

All-Fused-Silica Technology for On-Chip High Power Applications

Silica-on-Silica technology enables fabrication of waveguide-based on-chip devices for high-power applications. We demonstrate a 25µm thick Yb/Al-codoped fused silica slab waveguide with 0.2dB/cm loss and 0.6dB/cm gain, and a 25X25µm all-fused-silica rectangular waveguide.

Design, Fabrication and Characterization of Thermally Evaporated Photonic Crystal Mirrors.

In the present work, we design and fabricate omnidirectional mirrors based on 1D photonic crystals made of chalcogenide and cryolite using thermal evaporation. In particular, a two-dimensional mapping that provides a direct, visual signature of the mirrors is proposed. An experimental measurement of the reflectivity is shown. Finally a mirror with an omnidirectional reflectivity of more than 94% for a general polarization, a TE omnidirectional reflectivity of more than 99%, and a TE reflectivity of more than 99.99% for high incident angles is presented. The surface roughness of the mirrors is less than 5nm.