Multifunctional Optical Device with a Continuous Tunability over 500 nm Spectral Range Using Polymerized Cholesteric Liquid Crystals

Abstract

We report that polymerization makes a robust, practically applicable multifunctional optical device with a continuous wavelength tunable over 500 nm spectral range using UV-polymerizable cholesteric liquid crystals (CLCs). It can be used as a circular polarizer generating an extremely high degree of circularly polarized light with |g| = 1.85~2.00. It can also be used for optical notch filters, bandwidth-variable (from ~28 nm to ~93 nm) bandpass filters, mirrors, and intensity-variable beam splitters. Furthermore, this CLC device shows excellent stability owing to the polymerization of CLC cells. Its performance remains constant for a long time (~2 years) after a high-temperature exposure (170 °C for 1 h) and an extremely high laser beam intensity exposure (~143 W/cm2 of CW 532 nm diode laser and ~2.98 MW/cm2 of Nd: YAG pulse laser operation for two hours, respectively). The optical properties of polymerized CLC were theoretically analyzed by Berreman’s 4 × 4 matrix method. The characteristics of this device were significantly improved by introducing an anti-reflection layer on the device. This wavelength-tunable and multifunctional device could dramatically increase optical research efficiency in various spectroscopic works. It could be applied to many instruments using visible and near-infrared wavelengths.

Quickly Formed Continuously Tuneable Laser in the Full Visible Spectrum Using Cholesteric Liquid Crystal Cells Based on the Electrothermal Effect

“…The PBG position can be adjusted through the pitch and refractive index of NLCs by altering the relative weight ratio of the chiral material to the NLC, [3][4][5] temperature, [6][7][8] or external electric field [9][10][11][12][13] or through photoinduced trans-cis isomerization. [14][15][16] To date, various types of CLC laser devices have been developed, [17,18] and many excellent results have been reported. Jeong et al developed wavelength-tuneable CLC laser array devices capable of continuous wavelength tuning in the full visible spectrum by forming a chiral concentration gradient in dye-doped CLC wedge cells.…”

“…To date, various types of CLC laser devices have been developed, [ 17,18 ] and many excellent results have been reported. Jeong et al.…”

Continuously tuneable laser in the full visible spectrum formed in 10 minutes with cholesteric liquid crystal cells based on the electrothermal effect

“…The PBG position can be adjusted through the pitch and refractive index of NLCs by altering the relative weight ratio of the chiral material to the NLC 4,2,5 , temperature [6][7][8] , or external electric field [9][10][11][12][13] or through photoinduced trans-cis isomerization [14][15][16] . To date, various types of CLC laser devices have been developed 17,18 , and many excellent results have been reported. M.-Y.…”

Optical Filters Based on Cholesteric, Blue and Sphere Mesophases

“…TSLCs show a good application in optical communication devices, such as wavelength-selective filters, optical attenuators, optical switches, and beam steerers [13][14][15]. The wavelength range of TSLCs can be tuned by doping different concentrations of chiral dopant, forming spatial gradients, designing device structure, applying temperature, or irradiating the material with ultraviolet light [16][17][18][19], which makes them attractive in tunable optical filters [20][21][22][23]. Gao et al reported the development of templated TSLCs and summarized the potential photonic applications, including lasing, optical filters, grating, etc.…”