Alteration of optical Bragg phenomenon by substrate roughness

Abstract

A Bragg mirror is a dielectric slab that is periodically nonhomogeneous in the thickness direction. It displays the Bragg phenomenon as a high-reflectance spectral regime that depends on the direction of propagation and the polarization state of the incident light. Implicit in both theoretical treatments and fabrication procedures is the smoothness of the surface on which the Bragg mirror is fabricated. We have found that the Bragg phenomenon exhibited in the visible regime by periodically nonhomogeneous thin films grown on glass substrates can be significantly affected, even nullified, by pre-fabrication roughening of the surface of the substrate.

On temporally periodic physical vapor deposition on random rough surfaces

“…The substrate holder was kept stationary for 324.55 s for the deposition of each CTF, after some preliminary experiments. 38 The substrate holder was rotated by 180 deg about a central normal axis (the z axis) passing through it for 0.450 s between the depositions of any two consecutive CTFs. The deposition rate, as read through a quartz crystal monitor inside the chamber, was manually maintained at 0.4 AE 0.02 nm s −1 .…”