Detection of phase transitions from the study of whispering gallery mode resonance in liquid crystal droplets

Abstract

We report studies on the whispering gallery mode (WGM) resonance of liquid crystal (LC) droplets across the smectic-A (SmA) to nematic phase transition. The quality factor (Q) in the SmA phase decreases rapidly with a characteristic slope change at the SmA-N transition. In the SmA phase, Q-factor is linearly proportional to the birefringence (Δn). We discuss the effect of topological defect transformation on the WGM resonance. The study of WGM resonance is expected to be very useful for detecting subtle phase transitions among LC mesophases.