Ferroelectric nematic materials for high-speed electro-optic applications

Recently discovered ferroelectric nematic liquid crystals (FNLCs) offer the opportunity to make liquid crystal-based, high-speed electro-optic devices. The lack of a center of symmetry combined with having the polar axis oriented parallel to the long, polarizable molecular axis allows for large second-order nonlinear optical susceptibility and therefore a large Pockels effect. The electro-optic response at high frequencies is purely electronic, making possible high-speed modulators with bandwidths limited only by device architecture. Facile and thermodynamically stable alignment of the polar axis over large areas makes FNLCs an attractive alternative to organic crystals and poled polymers, which have been pursued for decades as Pockels materials. A novel methodology for characterizing the electro-optic coefficient (r(33)) of this new class of Pockels material was developed. Using this methodology, FNLCs engineered to have large nonlinearities were demonstrated to have r(33) values approaching that of lithium niobate.