On alignment of nematic liquid crystals infiltrating chiral sculptured thin films

Abstract

A structurally right-handed chiral sculptured thin film (STF) with a central 90 degtwist defect was made by thermal evaporation of chalcogenide glass and the use of a serial bideposition process to exhibit a narrowband hole in the spectrum of the right-circularly polarized light reflected when right-circularly polarized light is normally incident on the chiral STF. In an attempt to build a tunable filter, the chiral STF was then infiltrated with a highly birefringent nematic liquid crystal (LC), which caused a linear reflectance peak to redshift by ∼350 nm. But the circular Bragg phenomenon exhibited by the uninfiltrated chiral STF was greatly diminished owing to the similarity in the constitutive properties of the LC and the chalcogenide glass. No temperature dependence of the shifted peak was observed, which provided clear evidence that the LC molecules are not ordered inside the chiral STF but are randomly aligned instead.

Plasmonic Sensing Using Metallic Nano‐Sculptured Thin Films

“…This photonic crystal type nSTF structure was shown to act as a biosensor for water as well as for enhancing the efficiency of luminescence . When filled with electrooptic material such as liquid crystal it is even possible to tune their reflection peak …”

“…[ 82,83 ] When fi lled with electrooptic material such as liquid crystal it is even possible to tune their refl ection peak. [ 84 ] In the future more biosensing applications are expected to emerge, a fact which requires collaboration between physicists, biologists, biochemists and engineers to work on the surface functionalization problems, improve the specifi city of detection and build true functioning biosensing devices. Biofunctionalization of the nSTF surface is very important for specifi c and reliable sensing.…”

From bioinspired multifunctionality to mimumes

“…With periods on the order of 20 µm, the elastodynamic Bragg phenomenon 61 will be displayed at about 35 MHz, and the electromagnetic Bragg phenomenon 35 at about 10 THz. Dyes could be co-deposited, 62 quantum-dot layers could be inserted as phase defects, 63 and liquid crystals could be made to infiltrate 64 these mimumes for optical and electrooptical functionalities. Dye-impregnated mimumes could serve as luminescent concentrators 62 for the harvesting of light by photovoltaic solar cells, while unimpregnated mimumes on solar-cell surfaces could serve as trappers of solar light due to multiple scattering.…”