In this letter, characteristic matrix method was used to calculate the transmittance spectra of the one-dimensional photonic crystals (1-DPCs) with single defects in the center. From altering the refractive indexes n2’ and n3’ respectively for the defect, the transmittance spectra were calculated. From them, it shown that for the certain numerical value n3’=5.0, during the course of n2’ increased from 1.1 to 3.5, when it upped to 2.0, there occurred defect band gap in the stop band gap, and the defect band gap is at frequencies between 0.24~0.30. Besides, for n2’ =2.0, when n3’ increased from 1.1 to 3.5, there also occurred defect band gap in the stop band gap, and the defect band gap is at frequencies between 0.26~0.32. In addition, in these two progresses, the transmittance increased firstly and then decreased in the defect band gap.
Optical transmission spectra of one-dimensional photonic crystals with a mirror symmetry