All-optically controllable and highly efficient scattering mode light modulator based on azobenzene liquid crystals and poly(N-vinylcarbazole) films.
The present study reports that isothermal phase transition induced by photoisomerization of azobenzene liquid crystals (azo-LCs) from trans- to cis-isomers results in the dissolution of poly(N-vinylcarbazole) (PVK) into azo-LCs. Transparent (scattering) states can be demonstrated using uniform (rough) morphologies of PVK generated by slow (rapid) phase separation of PVK and azo-LCs from cis- to trans-isomers. The PVK films were examined in detail using scanning electron microscopy. Scattering performance resulting from the rough PVK surface induced micron-sized LC domains, and transparent performance resulting from the reformed uniform PVK surface can be optically and reversibly switched. Finally, all-optically controllable and highly efficient (contrast ratio of 370:1) scattering mode light modulators based on azo-LCs and PVK films were demonstrated.
Department of Photonics, National Cheng Kung University, Tainan 701, Taiwan.
Yen-Chen
YC
Liu
Ko-Ting
KT
Cheng
Yuan-Di
YD
Chen
Andy Ying-Guey
AY
Fuh
D001391:Azo Compounds / Q000737:chemistry* / Q000528:radiation effects; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D050866:Liquid Crystals / Q000737:chemistry* / Q000528:radiation effects; D008567:Membranes, Artificial; D011145:Polyvinyls / Q000737:chemistry* / Q000528:radiation effects; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000295:instrumentation*; D013685:Telecommunications / Q000295:instrumentation*
D001391:Azo Compounds; D008567:Membranes, Artificial; D011145:Polyvinyls; C035125:poly-N-vinylcarbazole; C009850:azobenzene