Refractive Index Dispersion and Anisotropic Group Refractive Indices of Rubrene Crystals

抄録

We have determined refractive indices of rubrene crystals in the wavelength regions where their emissions were observed. For this purpose, we grew in a vapor phase the rubrene crystals having both horizontal and vertical pairs of parallel crystal facets. The facets functioned as optical resonators that produced interference fringes in the emission and reflectance spectra. From the fringes in the emission spectrum, we estimated the dispersion of the phase refractive index along the crystal a-axis. The anisotropic group refractive indices were evaluated along the b- and c-axes from the fringes in the reflectance spectra. The experimental indices were compared with those computed from the density functional theory.