Optical properties of Pb1-xGexTe films

Study of Pb1-xGexTe films deposited by PVD revealed that Pb1-xGexTe is a ki nd of fine characteristic infrared materials, which has a high transmission in the spectral range 3 similar to 25 mum, and has indices of refraction i n the range 4.8 similar to5.6 at room temperature. Optical properties, whic h include transmission spectrum, dispersion spectrum and temperature coeffi cient dn/dT of refractive index, depend strongly on content x, environmenta l temperature and deposition conditions. It can be found that proper change of content x and deposition conditions may result in the change of tempera ture coefficient dn/dT of refractive index from negative to zero, and to po sitive from zero, which is of significance for manufacturing highly stable infrared optical filters.