Form birefringence of SiO_2/Ta_2O_5 periodic multilayers

Abstract

Dielectric multilayers consisting of alternating layers of SiO2 and Ta2O5 with a period as short as 42 nm are fabricated by sputtering. Their birefringent properties are analyzed by polarization-dependent etalon characteristics. Principal refractive indices and birefringence are controlled by the layer thickness ratio and are in good agreement with the theory. An extremely large birefringence of Δn = 0.13, close to the theoretical maximum, is achieved. A relatively short period compared to the wavelength of light contributes to low dispersion. These multilayers are potentially useful as artificial birefringent media in integrated optics.