Photochemical On–Off Switching of One-Dimensional Photonic Crystals Consisting of Azo-Functionalized Liquid Crystal Polymer and Polyvinyl Alcohol

Abstract

One-dimensional (1D) photonic crystals (PCs) are prepared from multi-bilayered films stacked with alternating azo-functionalized liquid crystal polymer (PAz) films and polyvinyl alcohol (PVA) films. Reflection with a wavelength that depends on the thickness of the films is observed, and the reflection can be turned on and off by switching between the two states, based on whether there is a difference in the refractive index between the two films. The refractive index change of PAz can be photochemically caused by a phase transition, based on the alignment states of the liquid crystal (LC). In this review, we focused on an effective photo-induced on-off switching approach in 1D PCs using LC properties and described the basic optical and chemical principles, the experimental results, and further optimizations.

Hydrogel-Based Colloidal Photonic Crystal Devices for Glucose Sensing

“…PCs with different dimensionally ordered structures are prepared in different ways. Assembled 1D PCs have been investigated as Bragg reflectors [7], whereas 2D/3D PCs have been extensively researched in areas related to displays, sensing, telecommunications, solar energy, and photocatalysis [8][9][10]. The most effective method to obtain periodic PBG structures is by self-assembly technology; such a method utilizes one or more kind(s) of colloidal particles that form periodic array structures by directional alignment under appropriate conditions.…”

Studying the impact of interface roughness on a layered photonic crystal as a sensor

“…The origins of Photonic band gaps (PBGs) are the structure's periodicity, the constituent materials' nature, and the number of layers in the structure [8]. The pioneering property of PBG of the periodic structures has many applications, such as sensors, filters, switches, photonic crystal waveguides, logic gates, and various optical integrated devices [9][10][11][12][13][14][15][16]. The PhCs are now expanding numerous fields, such as quantum computing, biophotonics, and communications [11,[17][18][19].…”

“…The pioneering property of PBG of the periodic structures has many applications, such as sensors, filters, switches, photonic crystal waveguides, logic gates, and various optical integrated devices [9][10][11][12][13][14][15][16]. The PhCs are now expanding numerous fields, such as quantum computing, biophotonics, and communications [11,[17][18][19]. The controllability of the PBG and optical properties depend on the use of prodigious materials, which can be modulated by external physical parameters such as magnetic field, voltage, temperature, and hydrostatic pressure [20][21][22][23][24][25].…”

Hyaluronic Acid Based Azo Polymer: Synthesis, Characterization, and Photo‐Responsiveness

“…[1][2][3][4][5][6][7][8][9][10] Due to the photo-induced cis-trans isomerization of the azobenzene chromophores, azo polymers showed many interesting properties, such as photo-induced surface relief structures, photo-induced dichroism or birefringence, and photo-induced deformation. [11][12][13][14][15] In addition, the azobenzene structure could be efficiently reduced by reductant, which has been well used in bio-imaging. [16][17][18] Anyway, the backbones of most reported azo polymers were petroleum-based polymers, such as polystyrene, polyurethane, or epoxy resin-based polymers.…”