Three-dimensional simulation of periodically structured thin films with uniaxial symmetry

Thin films were fabricated by glancing angle deposition (GLAD), a technique providing accurate control of the nanoscale geometry in the film. We demonstrate the ability of GLAD to create structures with a sinusoidal refractive index variation in the direction normal to the film surface. The structural periodicity prevents the transmission of light over a wide optical spectrum, creating a photonic stopband. By changing the parameters of the GLAD technique, a set of titanium dioxide films have been created exhibiting stopbands in desired spectral locations. Films with a predefined defect in the periodicity have also been designed and fabricated using the GLAD technique. Optical measurements of these samples have shown that the incorporation of a uniaxial defect layer into the film leads to the appearance of a transmittance peak within the stopband. We have performed finite-difference time-domain simulations of light transmission through the optical filters and calculated the photonic dispersion relation of idealized structures. By changing the geometry of the defect, the ability to control the location and width of the transmittance peak in the spectrum has been demonstrated. The theoretical results obtained demonstrate very good agreement with experimental measurements and allow one to make accurate predictions of the optical properties of GLAD fabricated thin films.