Large frequency range of negligible transmission in 1D photonic quantum   well structures
  We show that it is possible to enlarge the range of low transmission in 1D photonic crystals by using photonic quantum well structures. If a defect is introduced in the photonic quantum well structures, defect modes with a very high quality factor may appear. The transmission of the defect mode is due to the coupling between the eigenmodes of the defect and those at the band edges of the constituent photonic crystals. 
J. Zi, J. Wan, and C. Zhang