AbstractWe report for the first time the use of the relatively low index material SiON (n=1.56) for photonic crystal applications. With this system it is possible to enlarge the complete TE-band gap of a 2D-photonic crystal by properly designing the unit cell filling. This may be practically realised because of the larger dimensions of photonic crystals in low index materials, which allows less stringent etch conditions when compared to traditional InP based materials. The optimal distribution of the refractive index is found by placing the displacement field in high or in low dielectric material. The structure is defined by two figures of merit, the width of the band gap and the smallest feature size, which is the key factor in etching the structure. In addition, we suggest the use of a graded-index profile to reduce out of plane scattering. This graded index profile can be realised by controlling the nitrogen flow during deposition of the SiON layer.
Photonic crystal properties of packed submicrometric SiO2 spheres
