Polarity mapping in liquid crystals using laser-induced heating

The investigation of phase behaviour in the new class of materials showing ferroelectric nematic and related phases can greatly benefit from methods that combine thermal control with structural and polarity-sensitive imaging. In this work, we present a technique that integrates focused infrared laser heating with second harmonic generation microscopy, enabling rapid, localised control of temperature and simultaneous polarity-resolved imaging. This approach allows for spatially resolved visualisation of multiple coexisting liquid crystalline phases and their polar character in a single-shot experiment – significantly accelerating analysis compared to conventional heating-stage-based methods. We demonstrate the method on conventional nematic LCs and a complex ferroelectric nematic LC, resolving a rich sequence of mesophases and validating induced temperature profiles through numerical simulations. Our approach offers strong potential for high-throughput screening of novel materials and exploration of metastable phases.