We demonstrate that complete three-dimensional Photonic Band Gaps (PBG), spanning roughly 10% and 15% of the gap center frequency are attainable by incomplete infiltration of an opal with silicon and germanium, respectively [1]. In addition, we show that when an optically birefringent nematic liquid crystal is infiltrated into the void regions of an inverse opal PBG material, the resulting composite material exhibits a completely tunable PBG [2]. Measurements on analogous two-dimensional Photonic Crystals show that the photonic band edge may be shifted by more than 100 nm [3]. Furthermore, we present results of bandstructure calculations for Photonic Crystals whose constituent materials exhibit Faraday or natural optical activity. This provides additional flexibility for tuning the optical properties of Photonic Crystals.
[1] K. Busch and S. John, Phys. Rev. E 58, 3896 (1998)
[2] K. Busch and S. John, Phys. Rev. Lett. 83, 967 (1999)
[3] S.W. Leonard et al., Phys. Rev. B 61, R2389 (2000)
Work done in collaboration with S. John