Absorption and scattering measurements of nematic liquid crystals

Abstract

Absorption and scattering losses of visible radiation in nematic liquid crystals (LCs) were measured by an improved transmission technique. The absorption loss of the E-7 LC mixture was found to be ~1 order of magnitude larger than the scattering in the isotropic state. On the contrary, light scattering surpasses absorption by ~2 orders in the nematic state. Wavelength-dependent absorption and scattering losses of two LCs, E-7 and MBBA, were investigated at some laser wavelengths. Results indicate that the absorption tail of LCs decreases with wavelength as lambda(-2) and scattering as lambda(-4) as expected by theory.

Enhancement of the Nonlinear Optical Absorption of the E7 Liquid Crystal at the Nematic–Isotropic Transition

“…• C in the vicinity of T NI [20]. Linear scattering makes the transmitted power independent of the sample position, leading to a flat response in the normalized transmittance curve in an open-aperture Z-scan measurement.…”

Tuning the lateral leakage loss of TM-like modes in shallow-etched waveguides using liquid crystals

“…For E7, the total optical loss (i.e. scattering and absorption) is about 1 cm −1 at 1550 nm [20]. This corresponds to the imaginary part of the refractive index proportional to 10 −5 .…”

“…These can either be scattering or absorption losses. In the nematic state and for the wavelength range considered, the scattering loss can be 2 orders of magnitude stronger than the absorption loss [20]. Scattering losses arise from a lack of homogeneity in the alignment of the LC molecules above the waveguide.…”

Highdno/dTLiquid Crystals and their Applications in a Thermally Tunable Liquid Crystal Photonic Crystal Fiber

“…First, in this regime a small temperature fluctuation would cause a large dn o =dT change. Second, light scattering due to LC director fluctuations is strong near the phase transition [18]. Many devices are preferred to operate at room temperature.…”