Observation of applied voltage response of dye-doped liquid crystal by optical measurement of real and imaginary parts of complex refractive index

Abstract

The behavior of liquid crystal (LC) molecules and dye molecules in a dye-doped liquid crystal (DDLC) under a voltage application condition was quantitatively investigated. To observe the reorientation of these molecules, the real and imaginary parts of the complex refractive index were simultaneously and individually measured using an optical interferometer. The obtained results indicate that the alignment of dye molecules doped in DDLC occurs following the electrically responding LC molecules, near the Freedericksz transition region of LC.

Applied voltage response of a cholesteric liquid crystal cell observed by simultaneous measurement of phase and reflection changes based on optical interferometry

“…This optical system is constructed on the basis of Mach-Zehnder interferometry. Similar approaches to measuring the complex electro-optic constants of dye-doped polymers and dye-doped LCs are reported in our previous work 20,21). In this experiment, as a probe beam, an Nb:YAG laser and a diodepumped solid-state laser, whose wavelengths are 532 and 488 nm, were prepared.…”

“…Similar approaches to measuring the complex electro-optic constants of dye-doped polymers and dye-doped LCs are reported in our previous work. 20,21) In this experiment, as a probe beam, an Nb:YAG laser and a diodepumped solid-state laser, whose wavelengths are 532 and 488 nm, were prepared. These wavelengths are respectively located at left-and right-side lobes of the reflection band of the prepared CLC cell as shown in Fig.…”

“…In our recent study, we proposed a method using an optical interferometer to quantitatively measure the dynamics of a dye-doped LC for an electric field response. 20) Using this method, faint signal caused by molecular movement can be detected owing to a high sensitivity of the optical interferometer. In this study, we employ this method to quantitatively measure the dynamics of a CLC under a low-voltage application condition.…”