Abstract
Giant optical rotatory power for red and infrared light is realized along the c-axis using single crystals of the III2VI3 compound semiconductor ( Gax In1-x)2 Se3 by application of anomalous optical rotatory dispersion occurring at their absorption edges. By changing the composition x within the solid solution range from 0.03 to 0.70, the appropriate band gaps between 1.73 and 2.06 eV are selected and great rotatory power for light with specific wavelength longer than 600–700 nm is obtained. It is found that the greater the proportion of In atoms in the spirally ordered group-III atoms, the greater the optical rotatory power becomes. For single crystal ( Ga0.03 In0.97)2 Se3, a maximum rotatory power of 210°/mm is obtained at λ= 715 nm; the optical rotatory power is always above 90°/mm, being more than 8–15 times that of α-quartz.