Evidence of a minimum in refractive indexes of amorphous Ge_xTe_(100-x)fiIms: Relevance to the development of infrared waveguides

摘要

Investigation of Ge_xTe_(100-x) amorphous films deposited by thermal co-evaporation in a large zone of compositions revealed the presence of a minimum in the evolution of the refractive index in the range x ∈ [22;35]. Such a minimum has a great impact on the control of the film refractive index, an undeniable advantage for the manufacture of infrared waveguides. Indeed a similar fluctuation in the film composition in this zone during deposition results in a decrease in refractive index fluctuation by a factor of ～ 10 as compared to variation observed in other regions. On the left: planar waveguide formed by a Ge_xTe_(100-x) deposited onto an As_2Se_3 bulk glass; on the right: output of the m-lines experiment in the near infrared.