Ferroelectric liquid crystals: futuristic mesogens for photonic applications

Since their discovery in 1888, liquid crystals (LCs) have attracted an unceasing research interest due to their exceptional electro-optical properties that are crucial in the development of displays and modern photonic systems. The vast majority of research works in this domain include the usage of nematic liquid crystals (NLCs) which are repellent for the high-speed optical photonic devices due to their slow electro-optical response. However, in context of electro-optical response time and switch-on voltage, the NLCs still have a huge space to be improved in comparison to other competitive technological solutions. Alternatively, the most promising candidates for development of the next-generation LC-based photonic devices are chiral smectic C (SmC*) LCs, also known as ferroelectric liquid crystals (FLCs) with their microseconds response time and low power consumption. This review comprehensively evinces the recent advancement on the FLC-based photonic devices such as gratings, lenses, spatial light modulators, waveguides, etc. along with the various electro-optical switching modes in these devices. We have also discussed the boon and bane of the FLC materials which is essentially important for their futuristic photonic applications.