Inquisitive Optical and Electro-Optical Attributes of Azo-Dye Dispersed Nematic Liquid Crystal for Applications in Wavelength-Tunable Optical Filters
Shikha Agarwal, Bhupendra Pratap Singh, Shivangi Tripathi, Pankhuri Srivastava, Sonam Sharma, Rajiv Manohar
Abstract
The requirement of selecting a desired wavelength channel from a number of available wavelengths is of great research interest for application in advanced light-wave systems encompassing high-density wavelength-division multiplexed networks. Currently, available devices generally require a high power and complex instrumentation. In the present work, the performance parameters of a novel functional composite material have been augmented for wavelength selection purposes to meet the limitations of the existing technologies. The active material comprises commercially available nematic LC (E204) dispersed with optimized concentration of an organic azo-dye (methyl red crystals). A prototype of a LC-based optical filter has been fabricated, which tends to exhibit superior enhancement in the tunability range of transmitted wavelength and intensity of incident light with voltage control while operating at around 34% lower threshold voltage and a much faster (∼86.63%) response rate. The astounding features of this study include lowering of rise time and fall time of the optimized material composition by around 71.03 and 89.94%, respectively. The fabricated device structure serves as a potential candidate to be employed as a tunable filter. The spectral response shifts toward shorter-wavelength on strengthening the applied electric field across it, as confirmed by the transmission spectroscopic outcomes as well as polarized optical micrographs. Thermal stability of the device was observed to be enhanced for the system having higher concentrations of guest dye. Additionally, the system exhibits modulated photoluminescence emission and notable charge-storage capability with approximately 43% enhancement in capacitance that shall be further explored for future technologies based on energy harvesting purposes.