Novel tunable optical properties of liquid crystals, conjugated molecules and polymers in nanoscale periodic structures as photonic crystals

Abstract

Tunability of optical properties such as transmission and reflection by temperature and applied voltage has been demonstrated in synthetic opals and inverse opals like three‐dimensional photonic crystals infiltrated with liquid crystals, conjugated molecules and polymers, in accordance with theoretical calculation. A new type of tunability based on uncoupled mode in a two‐dimensional photonic band gap influenced by the field‐dependent anisotropy in liquid crystals has also been demonstrated theoretically. Spectral narrowing and lasing have been observed in these opals infiltrated with conducting polymers and fluorescent dyes like three‐dimensional photonic crystal and fluorescent dye‐doped cholesteric and ferroelectric liquid crystal as one‐dimensional photonic crystal. These lasing wavelength can be controlled by the applied voltage. Laser emission was also realized with conducting polymer on a surface relief grating formed on an azo‐polymer film by interference optical beam.

Water-Soluble Chemical Vapor Detection Enabled by Doctor-Blade-Coated Macroporous Photonic Crystals

“…However, a great majority of existing photonic crystal-based colorimetric sensors are restricted to detecting one certain chemical and unable to detect water vapors, which contain numerous water-soluble chemicals. Moreover, current lithographic technologies for fabricating photonic crystals are time-consuming and suffer from sophisticated equipment, whereas most self-assembled colloidal methodologies are only accessible for laboratory-scale fabrication [ 29 , 30 , 31 , 32 , 33 ]. It remains a challenge to engineer large-scale photonic crystals for colorimetric detection of water vapors consisting of broad-spectrum chemicals.…”

Anisotropic Accelerated Emission of the Chromophores in Photonic Crystals Consisting of a Polystyrene Opal Structure

“…These proposed schemes will create new interesting fields. In fact, there have been some reports on the concept to promote the electron transfer by suppressing the fluorescence in order to realize the high efficiency energy conversion. , Additionally, if it can be combined with the tuning of PBGs, the methods to control the excited states by external stimuli directly may be brought about to make the application of PCs much more wider. − …”

Interference color modulation, tunable refractive index, and chiroptical electrochromism in a π-conjugated polymer with cholesteric liquid crystal order

“…This light-selective property of CLC can be modified by appropriate adjustment of the half-pitch length through external stimuli, such as electrical potential. The helicity-related optical properties of CLCs have been applied in a range of functional optical devices, including lasing devices, [6][7][8] optical diodes, 9 and optical reflectors. 10 CLC has also been employed as a reaction field for the synthesis of optically active polymer films from optically inactive monomers.…”