Fabrication of Gradient Optical Filter Containing Anisotropic Bragg Nanostructure

Abstract

New gradient optical filters containing asymmetric Bragg structure were prepared from the distributed Bragg reflector (DBR) porous silicon (PSi). Anisotropic DBR PSi displaying a rainbow-colored reflection was generated by using an asymmetric etching configuration. Flexible anisotropic DBR PSi composite films were obtained by casting of polymer solution onto anisotropic DBR PSi thin films. The surface and cross-sectional images images of anisotropic DBR PSi composite films obtained with cold field emission scanning electron microscope indicated that the average pore size and the thickness of porous layer decreased as the lateral distance increased. As lateral distance increased, the reflection resonance shifted to shorter wavelength.

Adsorption and Desorption Characteristics of Gradient Distributed Bragg Reflector Porous Silicon Layers

“…The reflection resonances shifted to shorter wavelength with linear profile. 14 The surfaces of gradient PSi shown in The nanocapillary condensation and evaporation of vapors of methanol (97.48 mm Hg), benzene (80.85 mm Hg) and n-hexane (121.26 mm Hg) in gradient PSi were monitored by optical reflection spectroscopy in real time. Figure 4 displayed the change of reflection band of 700 nm in oxidized gradient PSi, when the hydrophilic surface of porous layer was exposed to the organic vapors.…”

“…13 Fabrication of gradient PSi whose pore sizes are varying as a function of lateral distance is reported. 14 As the lateral distance of gradient PSi increased, the shift of reflection band shows a linear relationship. * Authors to whom correspondence should be addressed.…”