Abstract
Theoritical analysis of high band gap Hgl-xCdxTe infrared absorption and consideration of the available metallurgical processes show the ability of this material to give rise to optical waveguides exhibiting characteristics equivalent or better than classical III V in-frared waveguides at 10.6 μm. The E.D.R.I. process (Isothermal Evaporation Diffusion) has been used to grow HgCdTe layer on CdTe substrates. The Hgl-xCdxTe (x = 0.5) source material has been obtained by the Travelling Heater Method. Exceptionally transparent material at 10.6 pm is obtained for Cd composition x greater than 0.5. The E.D.R.I. process produces graded composition layer ranging from x = 0.55 at the surface to x = 1 in the substrate, giving rise to highly transparent graded index waveguides. When a 10.6 μm beam is coupled by a high index Germanium prism with the waveguide modes, the totally reflected light exhibits m-lines at specific angles from which the effective indices of the waveguide modes are deduced. Then an inverse W.K.B. computation leads to the refractive index profile of the structure. The comparison with the Cadmium ratio obtained with the electron microprobe gives the relation between refractive index and Cadmium concentration. The propagation of a 10.6 μm wave exhibits an exceptionnally low attenuation (< 0.5 dB/cm) on all TE modes, even those of high order.© (1986) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.