Waveguides based on TeGe thick films for spatial interferometry

摘要

In the present paper we focus on the fabrication of waveguides which will be able to work in the large infrared window [6-20μm], compatible with the ESA requirements in the framework of the detection of Exo-solar planets by nulling interferometry.rnThe first step in the fabrication of such components is the realization of planar waveguides being able to guide light in this spectral range. In order to do so, telluride materials were selected: Te_(75)Ge_(15)Ga_(10) bulk glasses were chosen as substrates and TeGe films as guiding layers. The Te_(75)Ge_(15)Ga_(10) bulk glasses were purified during their synthesis which ensures an optimal transmission in the whole range from 6 to 20 μm. TeGe thick films with different compositions were deposited by thermal co-evaporation. Homogeneous films with thickness up to 15 microns could be produced. The M-lines measurement of their refractive index at λ= 10.6 μm highlighted a linear behavior versus the atomic percentage in tellurium and confirmed their compatibility for the project.rnFirst planar waveguides could be optically characterized after having prepared their input and output facets by an appropriate polishing procedure. Guidance of light was demonstrated in the whole range [6-20