K. M. A. Sobahan

Wideband circular polarization reflector fabricated by glancing angle deposition.

We demonstrate a wideband circular polarization reflector fabricated as cascades of helical films with different pitch thickness by using glancing angle deposition (GLAD) technique. The full-width-at-half-maximum bandwidth of this reflector is measured from the reflectance spectra and is found about 200 nm indicating the feasibility of wideband reflector. A helical TiO(2) film with three sections, each of different pitch thickness, is also studied. It shows three Bragg peaks at different wavelengths. To select appropriate material for this circular reflector, the optical properties of 5-turns TiO(2), ZrO(2), and Ta2O(5) helical films and the porosity effect on the TiO(2) helical film are investigated.

Linear polarization-discriminatory state inverter fabricated by oblique angle deposition.

In this paper, we report a linear polarization-discriminatory state inverter made of three-layer sculpture thin film fabricated by oblique angle deposition technique. The first and third layers are quarter-wave plates of zigzag structure and the middle of them is a circular Bragg reflector of left-handed helical structure. It is found that the normal incidence of P-polarized light on this polarization-discriminatory state inverter becomes the S-polarized light at output, while the incident S-polarized light of wavelength lying in the Bragg regime is reflected. The microstructure of the linear polarization-discriminatory state inverter is also investigated by using a scanning electron microscope.

Nanostructured optical thin films fabricated by oblique angle deposition

Oblique angle deposition (OAD) is a sophisticated technique to fabricate engineered nanostructured thin films for next generation optical nanodevices. In this technique, oblique angle deposition and substrate rotation are employed to control the columnar and helical nanostructures of thin films. The films deposited by this technique show the optical anisotropy, the porosity, or the chirality, depending on the controlled morphologies at the nano-scale. In this review paper, the nanostructured optical thin film devices, such as a circular polarization handedness inverter, a linear polarization-discriminatory inverter and the selective coatings on nanopatterns, are fabricated by electron beam evaporation using the OAD technique, and their optical and structural properties as nanooptical devices are described.

Optical Thin Film Linear-Polarization Selector Fabricated by Oblique Angle Deposition

In this study, a linear-polarization selector, made of a three-section sculptured thin film, is reported. Within the Bragg regime, the normal incident P-polarized light is transmitted through it, while the incident S-polarized light is reflected.

Handedness inversion of circularly polarized light realized with helical and zigzag films fabricated by glancing angle deposition

In this study, we investigate the circular polarization-handedness inverter consisted of helical and zigzag films. The incident circular polarized light on this device becomes opposite circular polarized light with Bragg effect at output.

Design of anisotropic reflector with birefringent thin films for use at normal incidence

In this paper, a design of anisotropic reflector with dielectric birefringent thin films for use with light at normal incident is presented. This reflector is assumed to be consisting of a stack of quarter-wave biaxial layers at design wavelength. The biaxial layers can be fabricated by oblique angle deposition technique. This designed is performed on glass substrate with TiO2 and SiO2.