Two color bandedge lasing from cholesteric liquid crystals in capillary

Nowadays, mirrorless lasing from dye-doped cholesteric liquid crystals (CLCs) have attracted much attention. To produce the CLCs, chiral materials are mixed into the nematic LCs and thus the rod-like LC molecules self-assembly aligned and rotated regularly along the helical axis to produce the one-dimensional photonic bandgap. The wavelength at long- and short-photonic band edges (λLWE and λSWE) are characterized by the relation λLWE = nep and λSWE = nop [1] in which p is helical pitch, where ne and no are extraordinary and ordinary refractive index. For the CLC lasers, the photon density will be enhanced at two bandedge so as to lower the lasing threshold [2]. Traditionally, the dye-doped CLC was infill into the cell constructed by the glass plate [3, 4]. In this work, we filled the dye-doped CLCs into the capillary tube to investigate the occurrence two lasing emission mode at bandedge of the photonics bandgap.