Abstract: Tunable photonic crystals offer an interesting possibility to adjust the photonic band gap (PBG) as per requirement. Various methods of achieving this have been tried that include polarization of liquid crystals, thermal effects and more. Chromogenic devices provided in accordance with the present invention include combinations and subcombinations of electrochromic, photochromic, thermochromic devices featuring TMO based inverse opals having tunable photonic band gaps (PBG) for certain frequencies. Electrochromic (EC) materials in which a reversible optical property change can be induced with the application of a small electric field offer a novel possibility to tune the PBG in a controlled and reversible way. The reversible chemical change and the ensuing change of optical constants in these periodically arranged EC materials make the PBG tunability possible. In a recent work we have demonstrated for the first time the PBG tunability of EC materials deposited in the form of periodic inverse opals.

Abstract: Tunable photonic crystals offer an interesting possibility to adjust the photonic band gap (PBG) as per requirement. Various methods of achieving this have been tried that include polarization of liquid crystals, thermal effects and more. Chromogenic devices provided in accordance with the present invention include combinations and subcombinations of electrochromic, photochromic, thermochromic devices featuring TMO based inverse opals having tunable photonic band gaps (PBG) for certain frequencies. Electrochromic (EC) materials in which a reversible optical property change can be induced with the application of a small electric field offer a novel possibility to tune the PBG in a controlled and reversible way. The reversible chemical change and the ensuing change of optical constants in these periodically arranged EC materials make the PBG tunability possible. In a recent work we have demonstrated for the first time the PBG tunability of EC materials deposited in the form of periodic inverse opals.