Abstract
Optical properties in a one - dimensional periodic structure having a nematic liquid crystal as a defect layer have been studied. Upon applying electric field, the position of the defect mode in the stop band can be controlled, which in attributed to the change in the effective refraction index caused by the field - induced reorientation of the liquid crystal molecules. Laser action at the localized mode in the band gap has been observed in the one - dimensional periodic structure which a dye - doped liquid crystal, and the lasing wavelength was tuned upon applying electric field.