High second harmonic generation in ferroelectric nematic liquid crystals by doping with optimally oriented chromophores

We report on the second harmonic generation performance of a ferroelectric nematic fluid consisting of the prototype ferroelectric nematic liquid crystal, RM734 mixed with the classical chromophore Dispersed-Orange 3 at 5 wt%. The mixture exhibits an interesting mesomorphic behaviour with a wide temperature range of the ferroelectric mesophase, high nematic order parameter and ease of alignment in cells. In the study, two fundamental wavelengths (1064 nm and 1574 nm) have been used in order to account for the second harmonic generation performance in absorbing and transparent regimens for the second harmonic light. For the fundamental wave the material is transparent in both cases. The results have been very outstanding and are among the highest for liquid crystals so far. Specifically, second order susceptibility tensor components of up to 25 pmV−1 and 8.5 pmV−1 have been obtained in the absorbing and transparent regimens, respectively. The mixing of chromophores with ferroelectric nematic liquid crystals is then established as a promising strategy in the search of high-performance nonlinear-optical mesogens.