Band Edge and Defect-Modes Lasing Due to Confinement of Helixed Liquid Crystals in Cylindrical Microcavities

Peculiar light emission properties have been observed in cylindrical microcavity hosting dye-doped helixed liquid crystals, which behaves as a fiber-like multidirectional distributed feedback laser. Experimental studies performed for this level of confinement show that laser action is exhibited both axially and radially, indicating a self-organized three-dimensional blue phase-like configuration. Thermal wavelength tunability was observed for both orientations emphasizing two different linear behaviors. The distributed feedback mechanism and the Q factor of the mirrorless resonant cavity result enhanced for axial stimulated emission because of the significant increase in the number of helical periods. In addition, long-lived spectrally narrow defect modes appear within the photonic band gap owing to optical phase jumps which take place in local structural defects.