TITLE:
Photonic Crystal Based Direct and Inverse Heterostructures by Colloidal Self-Assembly
AUTHORS:
Sunita Kedia, M. Srinivas Reddy, R. Vijaya
KEYWORDS:
Photonic Crystal; Heterostructure; Self-Assembly; Sol-Gel; Inverse Photonic Crystal; Dual Stop Bands
JOURNAL NAME:
Optics and Photonics Journal,
Vol.2 No.3A,
September
28,
2012
ABSTRACT: Photonic crystal heterostructures containing two materials and/or two lattice constants are synthesized using the colloids of polystyrene and polymethyl methacrylate by a self-assembling technique. These direct heterostructures with double stop band are infiltrated with zinc oxide by sol-gel method, followed by the removal of the original polymer template by a wet-etching process to result in inverse heterostructures made of zinc oxide. A red shift in the wavelength of stop bands is observed when the crystal is infiltrated with zinc oxide and a blue shift after inversion, in concurrence with the changes in the effective index of the structure. The stop band is also calculated to extract the number of layers and the extinction co-efficient contributing to the heterostructure. This structure made by a room-temperature low-cost technique produces a sparsely-filled zinc oxide crystal with a single refractive index but containing two different periodicities in a layered arrangement that can be used as a lab-on-a-chip for dual- or multi-wavelength sensing applications.