Optical Constants of Germanium: 3600 A to 7000 A

Abstract

The optical constants of single-crystal Ge, obtained from the ellipticity of reflected polarized light, exhibit two maxima. The real part of the index of refraction has maxima of 5.66 at 6000 A and 4.24 at 3900 A. The extinction coefficient has a maximum of 2.3 at 4900 A and another, just outside the range of the measurements, at about 3100 A with a value of about 3.3. The data are consistent with the Kramers-Kronig relations, and it is concluded that the absorption curve has only two maxima and rapidly approaches zero beyond 2500 A. There are significant differences between the five published measurements of the optical constants of Ge in the visible. Of the two previous works that used single-crystal material, the present results disagree with one and agree with the other which, however, covers over 700 A of the visible.