Wavelength-Selective Diffraction from Silica Thin-Film Gratings

Research output: Contribution to journalArticle

Authors

  • Ijaz Rashid
  • Ali K. Yetisen
  • Bruno Dlubak
  • James E. Davies
  • Pierre Seneor
  • Aymeric Vechhiola
  • Faycal Bouamrane
  • Stephane Xavier

Colleges, School and Institutes

External organisations

  • Microengineering and Nanotechnology Laboratory
  • HARVARD UNIVERSITY
  • Universite Paris Sud
  • Thales Research and Technology

Abstract

A reflective diffraction grating with a periodic square-wave profile will combine the effects of thin-film interference with conventional grating behavior when composed of features having a different refractive index than that of the substrate. A grating period of 700-1300 nm was modeled and compared for both silicon (Si) and silicon dioxide (SiO2) to determine the behavior of light interaction with the structures. Finite element analysis was used to study nanostructures having a multirefractive index grating and a conventional single material grating. A multimaterial grating has the same diffraction efficiency as that of a grating formed in a single material, but had the advantage of having an ordered relationship between the grating dimensions (thickness and period) and the intensity of reflected and diffracted optical wavelengths. We demonstrate a color-selective feature of the modeled SiO2 grating by fabricating samples with grating periods of 800 and 1000 nm, respectively. A high diffraction efficiency was measured for the green wavelength region as compared to other colors in the spectrum for 800 nm grating periodicity; whereas wavelengths within the red region of spectrum interfered constructively for the grating with 1000 nm periodicity resulting a higher efficiency for red color bandwidth. The results show that diffraction effects can be enhanced by the thin-film interference phenomenon to produce color selective optical devices.

Details

Original languageEnglish
Pages (from-to)2402-2409
Number of pages8
JournalACS Photonics
Volume4
Issue number10
Early online date12 Sep 2017
Publication statusPublished - 18 Oct 2017

Keywords

  • color-selective grating, diffraction gratings, nanotechnology, photonics, thin-film interference