The sol–gel method is an inexpensive and flexible liquid phase processing technique that is suitable for the fabrication of 1-D photonic bandgap structures, such as multilayer dielectric mirrors. In the present work, we started by preparing highly reflecting quarter-wave multilayer stacks, composed of alternating films of high refractive index material (TiO2) and low refractive index material (SiO2), possessing well-defined stop bands. For example, for a 11-layer stack, a stop band was obtained with more than 96% reflectance (at near-normal incidence) between ∼600 and 700 nm, with a gap to mid-gap ratio Δλ/λmax=15.4%. Fabry–Perot micro-cavities, containing high or low index defects within the quarter-wave stack, were also prepared and tested. Such structures were optimized with the help of suitable modeling, using transfer matrix techniques. Various experimental techniques were used to characterize these multilayers, including ellipsometry, visible spectroscopy, X-ray diffraction and atomic force microscopy.
[1]
Y. Fink,et al.
Dielectric omnidirectional visible reflector.
,
2001,
Optics letters.
[2]
A. Serpengüzel.
Amorphous silicon nitride microcavities
,
2001
.
[3]
Kazumi Wada,et al.
SiO2/TiO2 omnidirectional reflector and microcavity resonator via the sol-gel method
,
1999
.
[4]
M. Fox.
Optical Properties of Solids
,
2010
.
[5]
A. Lavrinenko,et al.
Observation of total omnidirectional reflection from a one-dimensional dielectric lattice
,
1998,
cond-mat/9811073.
[6]
Joakim Karlsson,et al.
Angle-resolved optical characterisation of an electrochromic device
,
2000
.
[7]
Winn,et al.
A dielectric omnidirectional reflector
,
1998,
Science.