  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.

Soft Condensed Matter